WorldWideScience

Sample records for high-redshift luminous infrared

  1. Luminous compact blue galaxies in the local Universe: A key reference for high-redshift studies

    Science.gov (United States)

    Pérez Gallego, J.; Guzmán, R.; Castander, F. J.; Garland, C. A.; Pisano, D. J.

    2005-05-01

    Luminous Compact Blue Galaxies (LCBGs) are high surface brightness starburst galaxies, bluer than a typical Sbc and brighter than ˜0.25Lstar. LCBGs have evolved more than any other galaxy class in the last ˜8 Gyr, and are a major contributor to the observed enhancement of the UV luminosity density of the Universe at z≤1. Despite the key role LCBGs may play in galaxy evolution, their statistical properties are still largely unknown. We have selected a complete sample of ˜25 LCBGs within 100 Mpc, after investigating over 106 nearby galaxies from the DR1 of the SDSS database. This sample, although small, provides an excellent reference for comparison with current and future surveys of similar galaxies at high redshift, including the population of Lyman-break galaxies. We present preliminary results of this study using 3D spectroscopic observations obtained over a very wide range in wavelength, using WIYN/DENSEPAK in the optical, FISICA in the infrared, and the VLA at cm wavelengths.

  2. The infrared-dark dust content of high redshift galaxies

    Science.gov (United States)

    Ferrara, A.; Hirashita, H.; Ouchi, M.; Fujimoto, S.

    2017-11-01

    We present a theoretical model aimed at explaining the IRX-β relation for high redshift (z ≳ 5) galaxies. Recent observations have shown that early Lyman-Break Galaxies, although characterized by a large ultraviolet (UV) attenuation (e.g. flat UV β slopes), show a striking far-infrared (FIR) deficit, i.e. they are `infrared-dark'. This marked deviation from the local IRX-β relation can be explained by the larger molecular gas content of these systems. While dust in the diffuse interstellar medium attains relatively high temperatures (Td ≃ 45 K for typical size a = 0.1 μm; smaller grains can reach Td ≳ 60 K), a sizable fraction of the dust mass is embedded in dense gas, and therefore remains cold. If confirmed, the FIR deficit might represent a novel, powerful indicator of the molecular content of high-z galaxies which can be used to pre-select candidates for follow-up deep CO observations. Thus, high-z CO line searches with ALMA might be much more promising than currently thought.

  3. Submillimetre observations of WISE-selected high-redshift, luminous AGN and their surrounding overdense environments

    Science.gov (United States)

    Jones, Suzy F.

    2016-08-01

    We present JCMT SCUBA-2 850 μm submillimetre (submm) observations of 10 mid-infrared (mid-IR) luminous active galactic nuclei (AGNs), detected by the Wide-field Infrared Survey Explorer (WISE) all-sky IR survey and 30 that have also been detected by the NVSS/FIRST radio survey. These rare sources are selected by their extremely red mid-IR spectral energy distributions (SEDs). Further investigations show that they are highly obscured, have abundant warm AGN-heated dust and are thought to be experiencing intense AGN feedback. When comparing the number of submm galaxies detected serendipitously in the surrounding 1.5 arcmin to those in blank-field submm surveys, there is a very significant overdensity, of order 3-5, but no sign of radial clustering centred at our primary objects. The WISE-selected AGN thus reside in 10-Mpc-scale overdense environments that could be forming in pre-viralized clusters of galaxies. WISE-selected AGNs appear to be the strongest signposts of high-density regions of active, luminous and dusty galaxies. SCUBA-2 850 μm observations indicate that their submm fluxes are low compared to many popular AGN SED templates, hence the WISE/radio-selected AGNs have either less cold and/or more warm dust emission than normally assumed for typical AGN. Most of the targets have total IR luminosities ≥1013 L⊙, with known redshifts of 20 targets between z ˜ 0.44-4.6.

  4. Mining the Infrared Sky for High-Redshift Quasars

    Science.gov (United States)

    Richards, Gordon

    The Spitzer and WISE satellites have opened up new avenues for the study of active galactic nuclei (AGN) by peering through the dust shrouding half (or more) of AGNs. However, despite being more sensitive to shrouded AGNs, current selection methods being used in the mid-IR are still largely blind to the highest redshift quasars-both those that are shrouded and those that are not (and should therefore be easy to find). We describe projects to identify both unobscured (at z>3) and obscured quasars (at z>2) that have heretofore been missed in significant numbers. Finding the high-z obscured quasars in large numbers is crucial for fulfilling the legacy of NASA missions in the IR and X-ray. With these quasars we will be able to perform clustering analyses that break the degeneracy of models describing how black holes can ``feed back" energy to the large-scale host galaxy, significantly influencing its evolution. We will further trace the luminosity function of galaxies undergoing active accretion from low-luminosity AGNs to luminous quasars—probing the growth of the supermassive black holes that we see today in the local universe. Our new insights come about from leveraging new Spitzer data, primarily from the PI's SpitzerIRAC Equatorial Survey (SpIES). The Spitzer data are 2.5 magnitudes deeper than the "AllWISE" survey in a 125 square degree, multiwavelength-rich, equatorial region known as SDSS "Stripe 82". These data are crucial for extending mid-IR investigations to higher redshifts, both for unobscured and obscured sources. The PI's team are among the world's experts in using the proposed machine learning techniques to find both unobscured (type-1) and obscured (type- 2) quasars and in using quasar clustering and luminosity functions to do cutting-edge science. The luminosity function and clustering algorithms are already in place, allowing for timely completion of this project once the multi-wavelength NASA data have been incorporated. This project is directly

  5. Infrared-faint radio sources in the SERVS deep fields. Pinpointing AGNs at high redshift

    Science.gov (United States)

    Maini, A.; Prandoni, I.; Norris, R. P.; Spitler, L. R.; Mignano, A.; Lacy, M.; Morganti, R.

    2016-12-01

    Context. Infrared-faint radio sources (IFRS) represent an unexpected class of objects which are relatively bright at radio wavelength, but unusually faint at infrared (IR) and optical wavelengths. A recent and extensive campaign on the radio-brightest IFRSs (S1.4 GHz≳ 10 mJy) has provided evidence that most of them (if not all) contain an active galactic nuclei (AGN). Still uncertain is the nature of the radio-faintest IFRSs (S1.4 GHz≲ 1 mJy). Aims: The scope of this paper is to assess the nature of the radio-faintest IFRSs, testing their classification and improving the knowledge of their IR properties by making use of the most sensitive IR survey available so far: the Spitzer Extragalactic Representative Volume Survey (SERVS). We also explore how the criteria of IFRSs can be fine-tuned to pinpoint radio-loud AGNs at very high redshift (z > 4). Methods: We analysed a number of IFRS samples identified in SERVS fields, including a new sample (21 sources) extracted from the Lockman Hole. 3.6 and 4.5 μm IR counterparts of the 64 sources located in the SERVS fields were searched for and, when detected, their IR properties were studied. Results: We compared the radio/IR properties of the IR-detected IFRSs with those expected for a number of known classes of objects. We found that IR-detected IFRSs are mostly consistent with a mixture of high-redshift (z ≳ 3) radio-loud AGNs. The faintest ones (S1.4 GHz 100 μJy), however, could be also associated with nearer (z 2) dust-enshrouded star-burst galaxies. We also argue that, while IFRSs with radio-to-IR ratios >500 can very efficiently pinpoint radio-loud AGNs at redshift 2 < z < 4, lower radio-to-IR ratios ( 100-200) are expected for higher redshift radio-loud AGNs.

  6. What powers luminous infrared galaxies?

    NARCIS (Netherlands)

    Lutz, D; Genzel, R; Sternberg, A; Netzer, H; Kunze, D; Rigopoulou, D; Sturm, E; Egami, E; Feuchtgruber, H; Moorwood, AFM; deGraauw, T

    1996-01-01

    Based on the initial data sets taken with the ISO short wavelength spectrometer (SWS) we present a first discussion of the source of luminosity of (ultra-)luminous infrared galaxies (ULIRGs). By comparison of observations of 2.5-45 mu m lines to classical starbursts and active galactic nuclei and by

  7. The Interstellar Medium in High-redshift Submillimeter Galaxies as Probed by Infrared Spectroscopy*

    Science.gov (United States)

    Wardlow, Julie L.; Cooray, Asantha; Osage, Willow; Bourne, Nathan; Clements, David; Dannerbauer, Helmut; Dunne, Loretta; Dye, Simon; Eales, Steve; Farrah, Duncan; Furlanetto, Cristina; Ibar, Edo; Ivison, Rob; Maddox, Steve; Michałowski, Michał M.; Riechers, Dominik; Rigopoulou, Dimitra; Scott, Douglas; Smith, Matthew W. L.; Wang, Lingyu; van der Werf, Paul; Valiante, Elisabetta; Valtchanov, Ivan; Verma, Aprajita

    2017-03-01

    Submillimeter galaxies (SMGs) at z≳ 1 are luminous in the far-infrared, and have star formation rates, SFR, of hundreds to thousands of solar masses per year. However, it is unclear whether they are true analogs of local ULIRGs or whether the mode of their star formation is more similar to that in local disk galaxies. We target these questions by using Herschel-PACS to examine the conditions in the interstellar medium (ISM) in far-infrared luminous SMGs at z˜ 1-4. We present 70-160 μm photometry and spectroscopy of the [O IV]26 μm, [Fe II]26 μm, [S III]33 μm, [Si II]34 μm, [O III]52 μm, [N III]57 μm, and [O I]63 μm fine-structure lines and the S(0) and S(1) hydrogen rotational lines in 13 lensed SMGs identified by their brightness in early Herschel data. Most of the 13 targets are not individually spectroscopically detected; we instead focus on stacking these spectra with observations of an additional 32 SMGs from the Herschel archive—representing a complete compilation of PACS spectroscopy of SMGs. We detect [O I]63 μm, [Si II]34 μm, and [N III]57 μm at ≥slant 3σ in the stacked spectra, determining that the average strengths of these lines relative to the far-IR continuum are (0.36+/- 0.12)× {10}-3, (0.84+/- 0.17)× {10}-3, and (0.27+/- 0.10)× {10}-3, respectively. Using the [O III]52 μm/[N III]57 μm emission line ratio, we show that SMGs have average gas-phase metallicities ≳ {Z}⊙ . By using PDR modeling and combining the new spectral measurements with integrated far-infrared fluxes and existing [C II]158 μm data, we show that SMGs have average gas densities, n, of ˜ {10}1-3 {{cm}}-3 and FUV field strengths, {G}0˜ {10}2.2-4.5 (in Habing units: 1.6× {10}-3 {erg} {{cm}}-2 {{{s}}}-1), consistent with both local ULIRGs and lower luminosity star-forming galaxies. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia, and important participation from NASA.

  8. Near-Infrared Follow-up of High Redshift X-ray Clusters

    Science.gov (United States)

    Barkhouse, Wayne; Green, Paul; Vikhlinin, Alexey; Kim, Dong-Woo

    2005-08-01

    Clusters of galaxies provide an intimate view of galaxy evolution over a wide range in cosmic look-back time and environment. From a large Chandra/NOAO serendipitous survey, we have culled a high- confidence list of high redshift cluster candidates to facilitate the investigation of galaxy cluster evolution and provide strong constraints on cosmological parameters. We propose to use FLAMINGOS on the KPNO 4-m telescope to obtain deep near-IR imaging in the J- and K_s-band of 6 extended X-ray sources discovered serendipitously in Chandra images, but undetected in deep 4m/MOSAIC imaging. Our FLAMINGOS observations will measure cluster redshifts (out to z~ 1.5) using the location of the cluster red-sequence in the color-magnitude plane. Cluster attributes, such as the luminosity function, richness, color-magnitude relation, and correlations between near-IR and X-ray properties, will be measured and contrasted with our more local serendipitous sample. These observations promise to substantially increase the number of known high redshift galaxy clusters.

  9. Constraints on cold dark matter theories from observations of massive x-ray-luminous clusters of galaxies at high redshift

    Science.gov (United States)

    Luppino, G. A.; Gioia, I. M.

    1995-01-01

    During the course of a gravitational lensing survey of distant, X-ray selected Einstein Observatory Extended Medium Sensitivity Survey (EMSS) clusters of galaxies, we have studied six X-ray-luminous (L(sub x) greater than 5 x 10(exp 44)(h(sub 50)(exp -2))ergs/sec) clusters at redshifts exceeding z = 0.5. All of these clusters are apparently massive. In addition to their high X-ray luminosity, two of the clusters at z approximately 0.6 exhibit gravitationally lensed arcs. Furthermore, the highest redshift cluster in our sample, MS 1054-0321 at z = 0.826, is both extremely X-ray luminous (L(sub 0.3-3.5keV)=9.3 x 10(exp 44)(h(sub 50)(exp -2))ergs/sec) and exceedingly rich with an optical richness comparable to an Abell Richness Class 4 cluster. In this Letter, we discuss the cosmological implications of the very existence of these clusters for hierarchical structure formation theories such as standard Omega = 1 CDM (cold dark matter), hybrid Omega = 1 C + HDM (hot dark matter), and flat, low-density Lambda + CDM models.

  10. Infrared-faint radio sources in the SERVS deep fields. Pinpointing AGNs at high redshift

    NARCIS (Netherlands)

    Maini, A.; Prandoni, I.; Norris, R. P.; Spitler, L. R.; Mignano, A.; Lacy, M.; Morganti, R.

    2016-01-01

    Context. Infrared-faint radio sources (IFRS) represent an unexpected class of objects which are relatively bright at radio wavelength, but unusually faint at infrared (IR) and optical wavelengths. A recent and extensive campaign on the radio-brightest IFRSs (S1.4 GHz≳ 10 mJy) has provided evidence

  11. Dense gas in luminous infrared galaxies

    NARCIS (Netherlands)

    Baan, W. A.; Henkel, C.; Loenen, A. F.; Baudry, A.; Wiklind, T.

    Aims. Molecules that trace the high-density regions of the interstellar medium have been observed in (ultra-) luminous (far-) infrared galaxies, in order to initiate multiple-molecule multiple-transition studies to evaluate the physical and chemical environment of the nuclear medium and its response

  12. Clumpy Star Formation in Local Luminous Infrared Galaxies

    Science.gov (United States)

    Larson, Kirsten; Armus, Lee; Diaz-Santos, Tanio; GOALS Team

    2018-01-01

    We present HST narrow-band imaging of Paβ and Paα emission in 50 local Luminous Infrared Galaxies from the Great Observatory All-Sky LIRG Survey (GOALS). These data allow us to study spatially resolved star forming regions and directly compare to star forming clumps found in both local and high-redshift galaxies. We find that the ionized gas is concentrated in star-forming clumps with sizes ranging from 70-700pc and star formation rates (SFRs) of .001 to 5 Msun yr-1. The SFRs of the clumps in GOALS spans the range from normal local galaxies to clump SFRs found in z=1-3 galaxies. The clumps have stellar ages of 5 x 106 to 4.5 x 107 yr with a median age of 8.6 x 106 yr and stellar masses of 106 to 109 Msun. The LIRGs in our sample cover the entire merger sequence from isolated galaxies to advanced staged mergers and allow us to study how the size, number, luminosity, and distribution of the clumpy star formation varies with the galaxy's merger stage, mass, and global star formation rates. Finally, we compare our results to clumpy star formation in high resolution hydrodynamical FIRE simulations and find that observed star forming clumps match the same size and star formation rate properties of those found in simulations.

  13. Infrared-faint radio sources are at high redshifts. Spectroscopic redshift determination of infrared-faint radio sources using the Very Large Telescope

    Science.gov (United States)

    Herzog, A.; Middelberg, E.; Norris, R. P.; Sharp, R.; Spitler, L. R.; Parker, Q. A.

    2014-07-01

    Context. Infrared-faint radio sources (IFRS) are characterised by relatively high radio flux densities and associated faint or even absent infrared and optical counterparts. The resulting extremely high radio-to-infrared flux density ratios up to several thousands were previously known only for high-redshift radio galaxies (HzRGs), suggesting a link between the two classes of object. However, the optical and infrared faintness of IFRS makes their study difficult. Prior to this work, no redshift was known for any IFRS in the Australia Telescope Large Area Survey (ATLAS) fields which would help to put IFRS in the context of other classes of object, especially of HzRGs. Aims: This work aims at measuring the first redshifts of IFRS in the ATLAS fields. Furthermore, we test the hypothesis that IFRS are similar to HzRGs, that they are higher-redshift or dust-obscured versions of these massive galaxies. Methods: A sample of IFRS was spectroscopically observed using the Focal Reducer and Low Dispersion Spectrograph 2 (FORS2) at the Very Large Telescope (VLT). The data were calibrated based on the Image Reduction and Analysis Facility (IRAF) and redshifts extracted from the final spectra, where possible. This information was then used to calculate rest-frame luminosities, and to perform the first spectral energy distribution modelling of IFRS based on redshifts. Results: We found redshifts of 1.84, 2.13, and 2.76, for three IFRS, confirming the suggested high-redshift character of this class of object. These redshifts and the resulting luminosities show IFRS to be similar to HzRGs, supporting our hypothesis. We found further evidence that fainter IFRS are at even higher redshifts. Conclusions: Considering the similarities between IFRS and HzRGs substantiated in this work, the detection of IFRS, which have a significantly higher sky density than HzRGs, increases the number of active galactic nuclei in the early universe and adds to the problems of explaining the formation of

  14. High Redshift Intergalactic C IV Abundance Measurements from the Near-Infrared Spectra of Two z~6 QSOs

    OpenAIRE

    Simcoe, Robert A.

    2006-01-01

    New measurements of the z~6 intergalactic CIV abundance are presented, using moderate resolution IR spectra of two QSOs taken with GNIRS on Gemini South. These data were systematically searched for high redshift CIV absorption lines, using objective selection criteria. Comprehensive tests were performed to quantify sample incompleteness, as well as the rate of false positive CIV identifications. The trend of constant $\\Omega_{CIV}(z)$ observed at z~2-5 appears to continue to z~6, the highest ...

  15. The Extremely Luminous Quasar Survey in the SDSS Footprint. I. Infrared-based Candidate Selection

    Science.gov (United States)

    Schindler, Jan-Torge; Fan, Xiaohui; McGreer, Ian D.; Yang, Qian; Wu, Jin; Jiang, Linhua; Green, Richard

    2017-12-01

    Studies of the most luminous quasars at high redshift directly probe the evolution of the most massive black holes in the early universe and their connection to massive galaxy formation. However, extremely luminous quasars at high redshift are very rare objects. Only wide-area surveys have a chance to constrain their population. The Sloan Digital Sky Survey (SDSS) has so far provided the most widely adopted measurements of the quasar luminosity function at z> 3. However, a careful re-examination of the SDSS quasar sample revealed that the SDSS quasar selection is in fact missing a significant fraction of z≳ 3 quasars at the brightest end. We identified the purely optical-color selection of SDSS, where quasars at these redshifts are strongly contaminated by late-type dwarfs, and the spectroscopic incompleteness of the SDSS footprint as the main reasons. Therefore, we designed the Extremely Luminous Quasar Survey (ELQS), based on a novel near-infrared JKW2 color cut using Wide-field Infrared Survey Explorer mission (WISE) AllWISE and 2MASS all-sky photometry, to yield high completeness for very bright ({m}{{i}}learning algorithms on SDSS and WISE photometry for quasar-star classification and photometric redshift estimation. The ELQS will spectroscopically follow-up ˜230 new quasar candidates in an area of ˜12,000 deg2 in the SDSS footprint to obtain a well-defined and complete quasar sample for an accurate measurement of the bright-end quasar luminosity function (QLF) at 3.0≤slant z≤slant 5.0. In this paper, we present the quasar selection algorithm and the quasar candidate catalog.

  16. Exploratory X-Ray Monitoring of Luminous Radio-quiet Quasars at High Redshift: No Evidence for Evolution in X-Ray Variability

    Science.gov (United States)

    Shemmer, Ohad; Brandt, W. N.; Paolillo, Maurizio; Kaspi, Shai; Vignali, Cristian; Lira, Paulina; Schneider, Donald P.

    2017-10-01

    We report on the second installment of an X-ray monitoring project of seven luminous radio-quiet quasars (RQQs). New Chandra observations of four of these, at 4.10≤slant z≤slant 4.35, yield a total of six X-ray epochs per source, with temporal baselines of ˜ 850{--}1600 days in the rest frame. These data provide the best X-ray light curves for RQQs at z> 4 to date, enabling qualitative investigations of the X-ray variability behavior of such sources for the first time. On average, these sources follow the trend of decreasing variability amplitude with increasing luminosity, and there is no evidence for X-ray variability increasing toward higher redshifts, in contrast with earlier predictions of potential evolutionary scenarios. An ensemble variability structure function reveals that their variability level remains relatively flat across ≈ 20{--}1000 days in the rest frame and it is generally lower than that of three similarly luminous RQQs at 1.33≤slant z≤slant 2.74 over the same temporal range. We discuss possible explanations for the increased variability of the lower-redshift subsample and, in particular, whether higher accretion rates play a leading role. Near-simultaneous optical monitoring of the sources at 4.10≤slant z≤slant 4.35 indicates that none is variable on ≈ 1 day timescales, although flux variations of up to ˜25% are observed on ≈ 100 day timescales, typical of RQQs at similar redshifts. Significant optical-X-ray spectral slope variations observed in two of these sources are consistent with the levels observed in luminous RQQs and are dominated by X-ray variations.

  17. High-redshift Galaxies and Black Holes Detectable with the JWST: A Population Synthesis Model from Infrared to X-Rays

    Science.gov (United States)

    Volonteri, Marta; Reines, Amy E.; Atek, Hakim; Stark, Daniel P.; Trebitsch, Maxime

    2017-11-01

    The first billion years of the Universe has been a pivotal time: stars, black holes (BHs), and galaxies formed and assembled, sowing the seeds of galaxies as we know them today. Detecting, identifying, and understanding the first galaxies and BHs is one of the current observational and theoretical challenges in galaxy formation. In this paper we present a population synthesis model aimed at galaxies, BHs, and active galactic nuclei (AGNs) at high redshift. The model builds a population based on empirical relations. The spectral energy distribution of galaxies is determined by age and metallicity, and that of AGNs by BH mass and accretion rate. We validate the model against observations, and predict properties of galaxies and AGN in other wavelength and/or luminosity ranges, estimating the contamination of stellar populations (normal stars and high-mass X-ray binaries) for AGN searches from the infrared to X-rays, and vice versa for galaxy searches. For high-redshift galaxies with stellar ages < 1 {Gyr}, we find that disentangling stellar and AGN emission is challenging at restframe UV/optical wavelengths, while high-mass X-ray binaries become more important sources of confusion in X-rays. We propose a color–color selection in the James Webb Space Telescope bands to separate AGN versus star-dominated galaxies in photometric observations. We also estimate the AGN contribution, with respect to massive, hot, and metal-poor stars, at driving high-ionization lines, such as C iv and He ii. Finally, we test the influence of the minimum BH mass and occupation fraction of BHs in low-mass galaxies on the restframe UV/near-IR and X-ray AGN luminosity function.

  18. High Redshift GRBs

    Science.gov (United States)

    Gehrels, Neil; Cannizzo, John K.

    2012-01-01

    The Swift mission has opened a new, high redshift window on the universe. In this review we provide an overview of gamma-ray burst (GRB) science, describe the Swift mission, discuss high-z GRBs and tools for high-z studies, and look forward at future capabilities. A new mission concept - Lobster - is described that would monitor the X-ray sky at order of magnitude higher sensitivity than current missions.

  19. Gemini Near-infrared Spectroscopy of Luminous z~6 Quasars

    DEFF Research Database (Denmark)

    Jiang, Linhua; Fan, Xiaohui; Vestergaard, Marianne

    2007-01-01

    We present Gemini near-infrared spectroscopic observations of six luminous quasars at z=5.8$\\sim$6.3. Five of them were observed using Gemini-South/GNIRS, which provides a simultaneous wavelength coverage of 0.9--2.5 $\\mu$m in cross dispersion mode. The other source was observed in K band with Ge...

  20. Planck intermediate results. XXVII. High-redshift infrared galaxy overdensity candidates and lensed sources discovered by Planck and confirmed by Herschel-SPIRE

    Science.gov (United States)

    Planck Collaboration; Aghanim, N.; Altieri, B.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Battaner, E.; Beelen, A.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bethermin, M.; Bielewicz, P.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Burigana, C.; Calabrese, E.; Canameras, R.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chary, R.-R.; Chiang, H. C.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Couchot, F.; Crill, B. P.; Curto, A.; Danese, L.; Dassas, K.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Falgarone, E.; Flores-Cacho, I.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frejsel, A.; Frye, B.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Guéry, D.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; Helou, G.; Hernández-Monteagudo, C.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Le Floc'h, E.; Leonardi, R.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; MacKenzie, T.; Maffei, B.; Mandolesi, N.; Maris, M.; Martin, P. G.; Martinache, C.; Martínez-González, E.; Masi, S.; Matarrese, S.; Mazzotta, P.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Natoli, P.; Negrello, M.; Nesvadba, N. P. H.; Novikov, D.; Novikov, I.; Omont, A.; Pagano, L.; Pajot, F.; Pasian, F.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ristorcelli, I.; Rocha, G.; Roudier, G.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Spencer, L. D.; Stolyarov, V.; Sunyaev, R.; Sutton, D.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Valtchanov, I.; Van Tent, B.; Vieira, J. D.; Vielva, P.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; Welikala, N.; Zacchei, A.; Zonca, A.

    2015-10-01

    We have used the Planck all-sky submillimetre and millimetre maps to search for rare sources distinguished by extreme brightness, a few hundred millijanskies, and their potential for being situated at high redshift. These "cold" Planck sources, selected using the High Frequency Instrument (HFI) directly from the maps and from the Planck Catalogue of Compact Sources (PCCS), all satisfy the criterion of having their rest-frame far-infrared peak redshifted to the frequency range 353-857 GHz. This colour-selection favours galaxies in the redshift range z = 2-4, which we consider as cold peaks in the cosmic infrared background. With a 4.´5 beam at the four highest frequencies, our sample is expected to include overdensities of galaxies in groups or clusters, lensed galaxies, and chance line-of-sight projections. We perform a dedicated Herschel-SPIRE follow-up of 234 such Planck targets, finding a significant excess of red 350 and 500μm sources, in comparison to reference SPIRE fields. About 94% of the SPIRE sources in the Planck fields are consistent with being overdensities of galaxies peaking at 350μm, with 3% peaking at 500μm, and none peaking at 250μm. About 3% are candidate lensed systems, all 12 of which have secure spectroscopic confirmations, placing them at redshifts z> 2.2. Only four targets are Galactic cirrus, yielding a success rate in our search strategy for identifying extragalactic sources within the Planck beam of better than 98%. The galaxy overdensities are detected with high significance, half of the sample showing statistical significance above 10σ. The SPIRE photometric redshifts of galaxies in overdensities suggest a peak at z ≃ 2, assuming a single common dust temperature for the sources of Td = 35 K. Under this assumption, we derive an infrared (IR) luminosity for each SPIRE source of about 4 × 1012L⊙, yielding star formation rates of typically 700 M⊙ yr-1. If the observed overdensities are actual gravitationally-bound structures

  1. High-redshift cosmography

    Science.gov (United States)

    Vitagliano, Vincenzo; Xia, Jun-Qing; Liberati, Stefano; Viel, Matteo

    2010-03-01

    We constrain the parameters describing the kinematical state of the universe using a cosmographic approach, which is fundamental in that it requires a very minimal set of assumptions (namely to specify a metric) and does not rely on the dynamical equations for gravity. On the data side, we consider the most recent compilations of Supernovae and Gamma Ray Bursts catalogues. This allows to further extend the cosmographic fit up to z = 6.6, i.e. up to redshift for which one could start to resolve the low z degeneracy among competing cosmological models. In order to reliably control the cosmographic approach at high redshifts, we adopt the expansion in the improved parameter y = z/(1+z). This series has the great advantage to hold also for z > 1 and hence it is the appropriate tool for handling data including non-nearby distance indicators. We find that Gamma Ray Bursts, probing higher redshifts than Supernovae, have constraining power and do require (and statistically allow) a cosmographic expansion at higher order than Supernovae alone. Exploiting the set of data from Union and GRBs catalogues, we show (for the first time in a purely cosmographic approach parametrized by deceleration q0, jerk j0, snap s0) a definitively negative deceleration parameter q0 up to the 3σ confidence level. We present also forecasts for realistic data sets that are likely to be obtained in the next few years.

  2. High-redshift cosmography

    Energy Technology Data Exchange (ETDEWEB)

    Vitagliano, Vincenzo; Xia, Jun-Qing; Liberati, Stefano [SISSA, Via Beirut 2-4, 34151 Trieste (Italy); Viel, Matteo, E-mail: vitaglia@sissa.it, E-mail: xia@sissa.it, E-mail: liberati@sissa.it, E-mail: viel@oats.inaf.it [INFN sez. Trieste, Via Valerio 2, 34127 Trieste (Italy)

    2010-03-01

    We constrain the parameters describing the kinematical state of the universe using a cosmographic approach, which is fundamental in that it requires a very minimal set of assumptions (namely to specify a metric) and does not rely on the dynamical equations for gravity. On the data side, we consider the most recent compilations of Supernovae and Gamma Ray Bursts catalogues. This allows to further extend the cosmographic fit up to z = 6.6, i.e. up to redshift for which one could start to resolve the low z degeneracy among competing cosmological models. In order to reliably control the cosmographic approach at high redshifts, we adopt the expansion in the improved parameter y = z/(1+z). This series has the great advantage to hold also for z > 1 and hence it is the appropriate tool for handling data including non-nearby distance indicators. We find that Gamma Ray Bursts, probing higher redshifts than Supernovae, have constraining power and do require (and statistically allow) a cosmographic expansion at higher order than Supernovae alone. Exploiting the set of data from Union and GRBs catalogues, we show (for the first time in a purely cosmographic approach parametrized by deceleration q{sub 0}, jerk j{sub 0}, snap s{sub 0}) a definitively negative deceleration parameter q{sub 0} up to the 3σ confidence level. We present also forecasts for realistic data sets that are likely to be obtained in the next few years.

  3. Galaxies at High Redshift

    Science.gov (United States)

    Bauer, F. E.

    2014-10-01

    Recent years have seen tremendous progress in finding and charactering star-forming galaxies at high redshifts across the electromagnetic spectrum, giving us a more complete picture of how galaxies evolve, both in terms of their stellar and gas content, as well as the growth of their central supermassive black holes. A wealth of studies now demonstrate that star formation peaked at roughly half the age of the Universe and drops precariously as we look back to very early times, and that their central monsters apparently growth with them. At the highest-redshifts, we are pushing the boundaries via deep surveys at optical, X-ray, radio wavelengths, and more recently using gamma-ray bursts. I will review some of our accomplishments and failures. Telescope have enabled Lyman break galaxies to be robustly identified, but the UV luminosity function and star formation rate density of this population at z = 6 - 8 seems to be much lower than at z = 2 - 4. High escape fractions and a large contribution from faint galaxies below our current detection limits would be required for star-forming galaxies to reionize the Universe. We have also found that these galaxies have blue rest-frame UV colours, which might indicate lower dust extinction at z > 5. There has been some spectroscopic confirmation of these Lyman break galaxies through Lyman-α emission, but the fraction of galaxies where we see this line drops at z > 7, perhaps due to the onset of the Gunn-Peterson effect (where the IGM is opaque to Lyman-α).

  4. Understanding Local Luminous Infrared Galaxies in the Herschel Era

    Science.gov (United States)

    Chu, Jason; Sanders, David B.; Larson, Kirsten L.; Mazzarella, Joseph M.; Howell, Justin; Diaz Santos, Tanio; Xu, C. Kevin; Paladini, Roberta; Schulz, Bernhard; Shupe, David L.; Appleton, Philip N.; Armus, Lee; Billot, Nicolas; Pan Chan, Hiu; Evans, Aaron S.; Fadda, Dario; Frayer, David T.; Haan, Sebastian; Mie Ishida, Catherine; Iwasawa, Kazushi; Kim, Dong-Chan; Lord, Steven D.; Murphy, Eric J.; Petric, Andreea; Privon, George C.; Surace, Jason A.; Treister, Ezequiel; Great Observatories All-Sky LIRG Survey, Cosmic Evolution Survey

    2017-06-01

    Luminous and ultraluminous infrared galaxies [(U)LIRGs] are some of the most extreme objects in the universe with their elevated star formation rates and/or presence of a powerful AGN, playing a central role in the evolution of galaxies throughout cosmic history. The 201 local (U)LIRGs (zPACS and SPIRE far infrared image atlas of the entire GOALS sample (encompassing the 70-500 micron wavelength range), and demonstrate the excellent data quality. The Herschel GOALS images presented here are the highest resolution, most sensitive and comprehensive far-infrared imaging survey of the nearest (U)LIRGs to date. This allows us for the first time to directly probe the critical far infrared and submillimeter wavelength regime of these systems, enabling us to accurately determine the bolometric luminosities, infrared surface brightnesses, star formation rates, and dust masses and temperatures on spatial scales of 2-5 kpc. In addition, the superb resolution of Herschel means we can resolve many of the galaxy pairs and systems within the GOALS sample, allowing us to measure far infrared fluxes of component galaxies. Finally, using the Herschel photometry in conjunction with Spitzer, WISE, and IRAS data, I will show our first results on the global properties of (U)LIRGs such as their average 3-500 micron infrared SEDs and far infrared colors, and compare them to lower infrared luminosity objects. We will also compare and contrast their infrared SED shapes with previously published SED templates from the literature. If time permits, I will also show initial results from our rest-frame optical spectroscopy program on z~2.3 infrared selected galaxies in the COSMOS field.

  5. Probing the bias of radio sources at high redshift

    CSIR Research Space (South Africa)

    Passmoor, S

    2012-11-01

    Full Text Available The relationship between the clustering of dark matter and that of luminous matter is often described using the bias parameter. Here, we provide a new method to probe the bias of intermediate-to-high-redshift radio continuum sources for which...

  6. Clustering of very luminous infrared galaxies and their environment

    Science.gov (United States)

    Gao, YU

    1993-01-01

    The IRAS survey reveals a class of ultraluminous infrared (IR) galaxies (ULIRG's) with IR luminosities comparable to the bolometric luminosities of quasars. The nature, origin, and evolution of ULIRG's are attracting more and more attention recently. Since galaxy morphology is certainly a function of environment, morphological observations show that ULIRG's are interacting/merging galaxies, and some ULIRG's might be the dust-enshrouded quasars (S88) or giant ellipticals, the study of ULIRG's environment and large scale clustering effects should be worthwhile. ULIRG's and very luminous IR galaxies have been selected from the 2Jy IRAS redshift survey. Meanwhile, a catalog of IRAS groups of galaxies has been constructed using a percolation-like algorithm. Therefore, whether ULIRG's and/or VLIRG's have a group environment can be checked immediately. Other aspects of the survey are discussed.

  7. The Nature of Optically-Luminous Stellar Clusters in a Large Sample of Luminous Infrared Galaxies

    Science.gov (United States)

    Vavilkin, Tatjana

    2011-08-01

    Luminous Star Clusters (SCs) are fundamental building blocks of galaxies, and they provide basic information regarding the mechanisms of star formation and the process of galaxy formation and evolution. In my PhD thesis project I investigated properties of young SCs in a sample of 87 nearby Luminous Infrared Galaxies (LIRGs: LIR>10^11 L_sun) imaged with the Hubble Space Telescope's Advanced Camera for Surveys at 0.4μm (F435W) and 0.9μm (F814W). Many LIRGs are observed to be ongoing mergers of gas-rich disk galaxies. They contain extreme starbursts and hence are expected to host particularly rich and luminous populations of SCs. This project represents the largest sample of galaxies with uniformly characterized properties of their SC population. The size of the sample allows an identification of trends in SC properties with merger stage and star formation rate. A large fraction (∼17%) of the cluster population is younger than 10 Myr. There is uncertainty in the determination of the ages of the bulk of the SCs due to an age-extinction degeneracy--the majority of the detected cluster population may have ages of up to a few hundred Myr. The median SC luminosity function index of the LIRG sample is alpha=-1.8, which is in a good agreement with previously published studies in various galaxy types. This sample contains some of the most luminous clusters observed so far, with Mmax (F435W) exceeding -17 mag. LIRGs follow the "brightest cluster--star formation rate" correlation observed for lower luminosity star-forming galaxies quite closely, although a large degree of scatter possibly due to extinction and over-estimation of Star Formation Rates (SFRs) in galaxies containing an Active Galactic Nucleus (AGN) is present. Thus, the size-of-sample effect and the observed high SFRs are responsible for high luminosity of SCs found in LIRGs. The specific luminosity TL(F435W)--SFR(far-IR + far-UV) relation observed for nearby non-interacting spiral galaxies is not applicable

  8. An Infrared Census of DUST in Nearby Galaxies with Spitzer (DUSTiNGS). IV. Discovery of High-redshift AGB Analogs

    Science.gov (United States)

    Boyer, M. L.; McQuinn, K. B. W.; Groenewegen, M. A. T.; Zijlstra, A. A.; Whitelock, P. A.; van Loon, J. Th.; Sonneborn, G.; Sloan, G. C.; Skillman, E. D.; Meixner, M.; McDonald, I.; Jones, O. C.; Javadi, A.; Gehrz, R. D.; Britavskiy, N.; Bonanos, A. Z.

    2017-12-01

    The survey for DUST in Nearby Galaxies with Spitzer (DUSTiNGS) identified several candidate Asymptotic Giant Branch (AGB) stars in nearby dwarf galaxies and showed that dust can form even in very metal-poor systems ({\\boldsymbol{Z}}∼ 0.008 {Z}ȯ ). Here, we present a follow-up survey with WFC3/IR on the Hubble Space Telescope (HST), using filters that are capable of distinguishing carbon-rich (C-type) stars from oxygen-rich (M-type) stars: F127M, F139M, and F153M. We include six star-forming DUSTiNGS galaxies (NGC 147, IC 10, Pegasus dIrr, Sextans B, Sextans A, and Sag DIG), all more metal-poor than the Magellanic Clouds and spanning 1 dex in metallicity. We double the number of dusty AGB stars known in these galaxies and find that most are carbon rich. We also find 26 dusty M-type stars, mostly in IC 10. Given the large dust excess and tight spatial distribution of these M-type stars, they are most likely on the upper end of the AGB mass range (stars undergoing Hot Bottom Burning). Theoretical models do not predict significant dust production in metal-poor M-type stars, but we see evidence for dust excess around M-type stars even in the most metal-poor galaxies in our sample (12+{log}({{O}}/{{H}})=7.26{--}7.50). The low metallicities and inferred high stellar masses (up to ∼10 {M}ȯ ) suggest that AGB stars can produce dust very early in the evolution of galaxies (∼30 Myr after they form), and may contribute significantly to the dust reservoirs seen in high-redshift galaxies. Based on observations made with the NASA/ESA Hubble Space Telescope at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-14073.

  9. High angular resolution radio and infrared view of optically dark supernovae in luminous infrared galaxies

    Science.gov (United States)

    Mattila, Seppo; Kankare, Erkki; Kool, Erik; Romero-Cañizales, Cristina; Ryder, Stuart; Perez-Torres, Miguel

    2017-11-01

    In luminous and ultraluminous infrared galaxies (U/LIRGs), the infall of gas into the central regions strongly enhances the star formation rate (SFR), especially within the nuclear regions which have also large amounts of interstellar dust. Within these regions SFRs of several tens to hundreds of solar masses per year ought to give rise to core-collapse supernova (SN) rates up to 1-2 SNe every year per galaxy. However, the current SN surveys, almost exclusively being ground-based seeing-limited and working at optical wavelengths, have been blinded by the interstellar dust and contrast issues therein. Thus the properties and rates of SNe in the nuclear environments of the most prolific SN factories in the Universe have remained largely unexplored. Here, we present results from high angular resolution observations of nearby LIRGs at infrared and radio wavelengths much less affected by the effects of extinction and lack of resolution hampering the optical searches.

  10. VERY STRONG EMISSION-LINE GALAXIES IN THE WFC3 INFRARED SPECTROSCOPIC PARALLEL SURVEY AND IMPLICATIONS FOR HIGH-REDSHIFT GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Atek, H.; Colbert, J.; Shim, H. [Spitzer Science Center, Caltech, Pasadena, CA 91125 (United States); Siana, B.; Bridge, C. [Department of Astronomy, Caltech, Pasadena, CA 91125 (United States); Scarlata, C. [Department of Astronomy, University of Minnesota-Twin Cities, Minneapolis, MN 55455 (United States); Malkan, M.; Ross, N. R. [Department of Physics and Astronomy, University of California, Los Angeles, CA (United States); McCarthy, P.; Dressler, A.; Hathi, N. P. [Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States); Teplitz, H. [Infrared Processing and Analysis Center, Caltech, Pasadena, CA 91125 (United States); Henry, A.; Martin, C. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Bunker, A. J. [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Fosbury, R. A. E. [Space Telescope-European Coordinating Facility, Garching bei Muenchen (Germany)

    2011-12-20

    The WFC3 Infrared Spectroscopic Parallel Survey uses the Hubble Space Telescope (HST) infrared grism capabilities to obtain slitless spectra of thousands of galaxies over a wide redshift range including the peak of star formation history of the universe. We select a population of very strong emission-line galaxies with rest-frame equivalent widths (EWs) higher than 200 A. A total of 176 objects are found over the redshift range 0.35 < z < 2.3 in the 180 arcmin{sup 2} area that we have analyzed so far. This population consists of young and low-mass starbursts with high specific star formation rates (sSFR). After spectroscopic follow-up of one of these galaxies with Keck/Low Resolution Imaging Spectrometer, we report the detection at z = 0.7 of an extremely metal-poor galaxy with 12 + log(O/H) =7.47 {+-} 0.11. After estimating the active galactic nucleus fraction in the sample, we show that the high-EW galaxies have higher sSFR than normal star-forming galaxies at any redshift. We find that the nebular emission lines can substantially affect the total broadband flux density with a median brightening of 0.3 mag, with some examples of line contamination producing brightening of up to 1 mag. We show that the presence of strong emission lines in low-z galaxies can mimic the color-selection criteria used in the z {approx} 8 dropout surveys. In order to effectively remove low-redshift interlopers, deep optical imaging is needed, at least 1 mag deeper than the bands in which the objects are detected. Without deep optical data, most of the interlopers cannot be ruled out in the wide shallow HST imaging surveys. Finally, we empirically demonstrate that strong nebular lines can lead to an overestimation of the mass and the age of galaxies derived from fitting of their spectral energy distribution (SED). Without removing emission lines, the age and the stellar mass estimates are overestimated by a factor of 2 on average and up to a factor of 10 for the high-EW galaxies

  11. Search for High Redshift Galaxy Clusters

    Science.gov (United States)

    Haarsma, D. B.; Butler, A. R.; Donahue, M. E.; Bruch, S. S.

    2005-12-01

    Distant galaxy clusters are key to understanding many current questions in cosmology, structure formation, and galaxy evolution, yet few z>1 clusters have been identified. The ROSAT Optical X-ray Survey (Donahue et al. 2002 ApJ 569, 689) searched for galaxy clusters using both optical and x-ray detection methods. While many clusters appeared in both wavebands, 10 targets which showed extended x-ray emission (a unique signature of cluster gas) did not show significant I-band emission (expected from elliptical galaxies in the cluster). These targets may be galaxy clusters with redshift greater than 1, which would appear faint in I due to the 400 nm break in elliptical galaxy spectra. In J and K bands, such galaxies would be easier to detect, and in April 2005 we imaged the 10 fields in J and K with the FLAMINGOS camera on the NOAO 4m telescope. The infrared colors are useful in identifying clusters, because all elliptical galaxies in a cluster are expected to have similar colors (i.e. the red sequence). We report preliminary identifications of high redshift galaxy clusters in our sample.

  12. A Herschel/PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies

    Science.gov (United States)

    Díaz-Santos, T.; Armus, L.; Charmandaris, V.; Lu, N.; Stierwalt, S.; Stacey, G.; Malhotra, S.; van der Werf, P. P.; Howell, J. H.; Privon, G. C.; Mazzarella, J. M.; Goldsmith, P. F.; Murphy, E. J.; Barcos-Muñoz, L.; Linden, S. T.; Inami, H.; Larson, K. L.; Evans, A. S.; Appleton, P.; Iwasawa, K.; Lord, S.; Sanders, D. B.; Surace, J. A.

    2017-09-01

    We present an analysis of {[{{O}}{{I}}]}63, [O III]88, [N II]122, and {[{{C}}{{II}}]}158 far-infrared (FIR) fine-structure line observations obtained with Herschel/PACS, for ˜240 local luminous infrared galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey. We find pronounced declines (“deficits”) of line-to-FIR continuum emission for [N II]122, {[{{O}}{{I}}]}63, and {[{{C}}{{II}}]}158 as a function of FIR color and infrared luminosity surface density, {{{Σ }}}{IR}. The median electron density of the ionized gas in LIRGs, based on the [N II]122/[N II]205 ratio, is {n}{{e}} = 41 cm-3. We find that the dispersion in the {[{{C}}{{II}}]}158 deficit of LIRGs is attributed to a varying fractional contribution of photodissociation regions (PDRs) to the observed {[{{C}}{{II}}]}158 emission, f([{{C}} {{II}}{]}158{PDR}) = [{{C}} {{II}}{]}158{PDR}/{[{{C}}{{II}}]}158, which increases from ˜60% to ˜95% in the warmest LIRGs. The {[{{O}}{{I}}]}63/[{{C}} {{II}}{]}158{PDR} ratio is tightly correlated with the PDR gas kinetic temperature in sources where {[{{O}}{{I}}]}63 is not optically thick or self-absorbed. For each galaxy, we derive the average PDR hydrogen density, {n}{{H}}, and intensity of the interstellar radiation field, G, in units of {G}0 and find G/{n}{{H}} ratios of ˜0.1-50 {G}0 cm3, with ULIRGs populating the upper end of the distribution. There is a relation between G/{n}{{H}} and {{{Σ }}}{IR}, showing a critical break at {{{Σ }}}{IR}* ≃ 5 × 1010 L ⊙ kpc-2. Below {{{Σ }}}{IR}* , G/{n}{{H}} remains constant, ≃0.32 {G}0 cm3, and variations in {{{Σ }}}{IR} are driven by the number density of star-forming regions within a galaxy, with no change in their PDR properties. Above {{{Σ }}}{IR}* , G/{n}{{H}} increases rapidly with {{{Σ }}}{IR}, signaling a departure from the typical PDR conditions found in normal star-forming galaxies toward more intense/harder radiation fields and compact geometries typical of starbursting sources.

  13. Planck intermediate results XXVII. High-redshift infrared galaxy overdensity candidates and lensed sources discovered by Planck and confirmed by Herschel-SPIRE⋆

    DEFF Research Database (Denmark)

    Aghanim, N.; Altieri, B.; Arnaud, M.

    2015-01-01

    We have used the Planck all-sky submillimetre and millimetre maps to search for rare sources distinguished by extreme brightness, a few hundred millijanskies, and their potential for being situated at high redshift. These "cold" Planck sources, selected using the High Frequency Instrument (HFI) d...

  14. Herschel Observations of Far-infrared Cooling Lines in Intermediate Redshift (Ultra)-luminous Infrared Galaxies

    Science.gov (United States)

    Rigopoulou, D.; Hopwood, R.; Magdis, G. E.; Thatte, N.; Swinyard, B. M.; Farrah, D.; Huang, J.-S.; Alonso-Herrero, A.; Bock, J. J.; Clements, D.; Cooray, A.; Griffin, M. J.; Oliver, S.; Pearson, C.; Riechers, D.; Scott, D.; Smith, A.; Vaccari, M.; Valtchanov, I.; Wang, L.

    2014-01-01

    We report the first results from a spectroscopic survey of the [C II] 158 μm line from a sample of intermediate redshift (0.2 1011.5 L ⊙), using the Spectral and Photometric Imaging REceiver-Fourier Transform Spectrometer on board the Herschel Space Observatory. This is the first survey of [C II] emission, an important tracer of star formation, at a redshift range where the star formation rate density of the universe increases rapidly. We detect strong [C II] 158 μm line emission from over 80% of the sample. We find that the [C II] line is luminous, in the range (0.8-4) × 10-3 of the far-infrared continuum luminosity of our sources, and appears to arise from photodissociation regions on the surface of molecular clouds. The L [C II]/L IR ratio in our intermediate redshift (U)LIRGs is on average ~10 times larger than that of local ULIRGs. Furthermore, we find that the L [C II]/L IR and L [C II]/L CO(1-0) ratios in our sample are similar to those of local normal galaxies and high-z star-forming galaxies. ULIRGs at z ~ 0.5 show many similarities to the properties of local normal and high-z star-forming galaxies. Our findings strongly suggest that rapid evolution in the properties of the star-forming regions of (U)LIRGs is likely to have occurred in the last 5 billion years. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  15. Adaptive Optics Imaging Survey of Luminous Infrared Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Laag, E A; Canalizo, G; van Breugel, W; Gates, E L; de Vries, W; Stanford, S A

    2006-03-13

    We present high resolution imaging observations of a sample of previously unidentified far-infrared galaxies at z < 0.3. The objects were selected by cross-correlating the IRAS Faint Source Catalog with the VLA FIRST catalog and the HST Guide Star Catalog to allow for adaptive optics observations. We found two new ULIGs (with L{sub FIR} {ge} 10{sup 12} L{sub {circle_dot}}) and 19 new LIGs (with L{sub FIR} {ge} 10{sup 11} L{sub {circle_dot}}). Twenty of the galaxies in the sample were imaged with either the Lick or Keck adaptive optics systems in H or K{prime}. Galaxy morphologies were determined using the two dimensional fitting program GALFIT and the residuals examined to look for interesting structure. The morphologies reveal that at least 30% are involved in tidal interactions, with 20% being clear mergers. An additional 50% show signs of possible interaction. Line ratios were used to determine powering mechanism; of the 17 objects in the sample showing clear emission lines--four are active galactic nuclei and seven are starburst galaxies. The rest exhibit a combination of both phenomena.

  16. A Far-infrared Spectroscopic Survey of Intermediate Redshift (Ultra) Luminous Infrared Galaxies

    Science.gov (United States)

    Magdis, Georgios E.; Rigopoulou, D.; Hopwood, R.; Huang, J.-S.; Farrah, D.; Pearson, C.; Alonso-Herrero, Almudena; Bock, J. J.; Clements, D.; Cooray, A.; Griffin, M. J.; Oliver, S.; Perez Fournon, I.; Riechers, D.; Swinyard, B. M.; Scott, D.; Thatte, N.; Valtchanov, I.; Vaccari, M.

    2014-11-01

    We present Herschel far-IR photometry and spectroscopy as well as ground-based CO observations of an intermediate redshift (0.21 1011.5 L ⊙). With these measurements, we trace the dust continuum, far-IR atomic line emission, in particular [C II] 157.7 μm, as well as the molecular gas of z ~ 0.3 luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) and perform a detailed investigation of the interstellar medium of the population. We find that the majority of Herschel-selected intermediate redshift (U)LIRGs have L C II /L FIR ratios that are a factor of about 10 higher than that of local ULIRGs and comparable to that of local normal and high-z star-forming galaxies. Using our sample to bridge local and high-z [C II] observations, we find that the majority of galaxies at all redshifts and all luminosities follow an L C II -L FIR relation with a slope of unity, from which local ULIRGs and high- z active-galactic-nucleus-dominated sources are clear outliers. We also confirm that the strong anti-correlation between the L C II /L FIR ratio and the far-IR color L 60/L 100 observed in the local universe holds over a broad range of redshifts and luminosities, in the sense that warmer sources exhibit lower L C II /L FIR at any epoch. Intermediate redshift ULIRGs are also characterized by large molecular gas reservoirs and by lower star formation efficiencies compared to that of local ULIRGs. The high L C II /L FIR ratios, the moderate star formation efficiencies (L IR/L\\prime _CO or L IR/M_H2), and the relatively low dust temperatures of our sample (which are also common characteristics of high-z star-forming galaxies with ULIRG-like luminosities) indicate that the evolution of the physical properties of (U)LIRGs between the present day and z > 1 is already significant by z ~ 0.3.

  17. Overdensities of SMGs around WISE-selected, ultraluminous, high-redshift AGNs

    Science.gov (United States)

    Jones, Suzy F.; Blain, Andrew W.; Assef, Roberto J.; Eisenhardt, Peter; Lonsdale, Carol; Condon, James; Farrah, Duncan; Tsai, Chao-Wei; Bridge, Carrie; Wu, Jingwen; Wright, Edward L.; Jarrett, Tom

    2017-08-01

    We investigate extremely luminous dusty galaxies in the environments around Wide-field Infrared Survey Explorer (WISE)-selected hot dust-obscured galaxies (Hot DOGs) and WISE/radio-selected active galactic nuclei (AGNs) at average redshifts of z = 2.7 and 1.7, respectively. Previous observations have detected overdensities of companion submillimetre-selected sources around 10 Hot DOGs and 30 WISE/radio AGNs, with overdensities of ˜2-3 and ˜5-6, respectively. We find that the space densities in both samples to be overdense compared to normal star-forming galaxies and submillimetre galaxies (SMGs) in the Submillimetre Common-User Bolometer Array 2 (SCUBA-2) Cosmology Legacy Survey (S2CLS). Both samples of companion sources have consistent mid-infrared (mid-IR) colours and mid-IR to submm ratios as SMGs. The brighter population around WISE/radio AGNs could be responsible for the higher overdensity reported. We also find that the star formation rate densities are higher than the field, but consistent with clusters of dusty galaxies. WISE-selected AGNs appear to be good signposts for protoclusters at high redshift on arcmin scales. The results reported here provide an upper limit to the strength of angular clustering using the two-point correlation function. Monte Carlo simulations show no angular correlation, which could indicate protoclusters on scales larger than the SCUBA-2 1.5-arcmin scale maps.

  18. Expanding the Gamma-ray Universe: High Redshift Fermi-LAT Blazars

    Science.gov (United States)

    Ojha, Roopesh; Paliya, Vaidehi; Gasparrini, Dario; Ajello, Marco; Cutini, Sara; Fermi-LAT Collaboration

    2017-01-01

    High-redshift blazars detected by the Fermi Large Area Telescope (LAT) are of great astrophysical import as they are extreme objects whose energetics remain a mystery. Such blazars are intrinsically interesting since they inform us about the evolution of gamma-ray blazars and are, by definition, some of the more luminous blazars in the Fermi-LAT sample. These blazars appear to host very massive black holes and could shed light on the origin and growth of black holes in the early Universe. We present the latest high redshift blazar detections in the LAT and discuss some of their implications.

  19. Accurate Emission Line Diagnostics at High Redshift

    Science.gov (United States)

    Jones, Tucker

    2017-08-01

    How do the physical conditions of high redshift galaxies differ from those seen locally? Spectroscopic surveys have invested hundreds of nights of 8- and 10-meter telescope time as well as hundreds of Hubble orbits to study evolution in the galaxy population at redshifts z 0.5-4 using rest-frame optical strong emission line diagnostics. These surveys reveal evolution in the gas excitation with redshift but the physical cause is not yet understood. Consequently there are large systematic errors in derived quantities such as metallicity.We have used direct measurements of gas density, temperature, and metallicity in a unique sample at z=0.8 to determine reliable diagnostics for high redshift galaxies. Our measurements suggest that offsets in emission line ratios at high redshift are primarily caused by high N/O abundance ratios. However, our ground-based data cannot rule out other interpretations. Spatially resolved Hubble grism spectra are needed to distinguish between the remaining plausible causes such as active nuclei, shocks, diffuse ionized gas emission, and HII regions with escaping ionizing flux. Identifying the physical origin of evolving excitation will allow us to build the necessary foundation for accurate measurements of metallicity and other properties of high redshift galaxies. Only then can we expoit the wealth of data from current surveys and near-future JWST spectroscopy to understand how galaxies evolve over time.

  20. MID-INFRARED PROPERTIES OF NEARBY LUMINOUS INFRARED GALAXIES. I. SPITZER INFRARED SPECTROGRAPH SPECTRA FOR THE GOALS SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Stierwalt, S.; Armus, L.; Surace, J. A.; Inami, H.; Petric, A. O.; Diaz-Santos, T.; Haan, S.; Howell, J.; Marshall, J. [Spitzer Science Center, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Charmandaris, V. [Department of Physics and ITCP, University of Crete, GR-71003 Heraklion (Greece); Kim, D. C. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Mazzarella, J. M.; Chan, B. [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Spoon, H. W. W. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Veilleux, S. [Astronomy Department, University of Maryland, College Park, MD 20742 (United States); Evans, A. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Sanders, D. B. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96825 (United States); Appleton, P. [NASA Herschel Science Center, 770 S. Wilson Ave., Pasadena, CA 91125 (United States); Bothun, G. [Physics Department, University of Oregon, Eugene, OR 97402 (United States); Bridge, C. R., E-mail: sabrinas@virginia.edu [Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); and others

    2013-05-01

    The Great Observatories All-Sky LIRG Survey (GOALS) is a comprehensive, multiwavelength study of luminous infrared galaxies (LIRGs) in the local universe. Here we present low resolution Spitzer Infrared Spectrograph spectra covering 5-38 {mu}m and provide a basic analysis of the mid-IR spectral properties observed for nearby LIRGs. In a companion paper, we discuss detailed fits to the spectra and compare the LIRGs to other classes of galaxies. The GOALS sample of 244 nuclei in 180 luminous (10{sup 11} {<=} L {sub IR}/L {sub Sun} < 10{sup 12}) and 22 ultraluminous (L {sub IR}/L {sub Sun} {>=} 10{sup 12}) IR galaxies represents a complete subset of the IRAS Revised Bright Galaxy Sample and covers a range of merger stages, morphologies, and spectral types. The majority (>60%) of the GOALS LIRGs have high 6.2 {mu}m polycyclic aromatic hydrocarbon (PAH) equivalent widths (EQW{sub 6.2{mu}m} > 0.4 {mu}m) and low levels of silicate absorption (s {sub 9.7{mu}m} > -1.0). There is a general trend among the U/LIRGs for both silicate depth and mid-infrared (MIR) slope to increase with increasing L {sub IR}. U/LIRGs in the late to final stages of a merger also have, on average, steeper MIR slopes and higher levels of dust obscuration. Together, these trends suggest that as gas and dust is funneled toward the center of a coalescing merger, the nuclei become more compact and more obscured. As a result, the dust temperature increases also leading to a steeper MIR slope. The sources that depart from these correlations have very low PAH equivalent width (EQW{sub 6.2{mu}m} < 0.1 {mu}m) consistent with their emission being dominated by an active galactic nucleus (AGN) in the MIR. These extremely low PAH EQW sources separate into two distinct types: relatively unobscured sources with a very hot dust component (and thus very shallow MIR slopes) and heavily dust obscured nuclei with a steep temperature gradient. The most heavily dust obscured sources are also the most compact in their MIR

  1. High-redshift SDSS Quasars with Weak Emission Lines

    DEFF Research Database (Denmark)

    Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Brandt, W. N.

    2009-01-01

    We identify a sample of 74 high-redshift quasars (z > 3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z > 4. These weak emission-line quasars (WLQs) constitute a prominent...... rest-frame 0.1-5 µm spectral energy distributions that are quite similar to those of normal quasars. The variability, polarization, and radio properties of WLQs are also different from those of BL Lacs, making continuum boosting by a relativistic jet an unlikely physical interpretation. The most...

  2. Planck intermediate results. XXXIX. The Planck list of high-redshift source candidates

    Science.gov (United States)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Burigana, C.; Butler, R. C.; Calabrese, E.; Catalano, A.; Chiang, H. C.; Christensen, P. R.; Clements, D. L.; Colombo, L. P. L.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Dickinson, C.; Diego, J. M.; Dole, H.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Finelli, F.; Flores-Cacho, I.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Harrison, D. L.; Helou, G.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Nati, F.; Natoli, P.; Nesvadba, N. P. H.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paoletti, D.; Partridge, B.; Pasian, F.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Pettorino, V.; Piacentini, F.; Piat, M.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Spencer, L. D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Türler, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, F.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; Welikala, N.; Yvon, D.; Zacchei, A.; Zonca, A.

    2016-12-01

    The Planck mission, thanks to its large frequency range and all-sky coverage, has a unique potential for systematically detecting the brightest, and rarest, submillimetre sources on the sky, including distant objects in the high-redshift Universe traced by their dust emission. A novel method, based on a component-separation procedure using a combination of Planck and IRAS data, has been validated and characterized on numerous simulations, and applied to select the most luminous cold submillimetre sources with spectral energy distributions peaking between 353 and 857 GHz at 5' resolution. A total of 2151 Planck high-z source candidates (the PHZ) have been detected in the cleanest 26% of the sky, with flux density at 545 GHz above 500 mJy. Embedded in the cosmic infrared background close to the confusion limit, these high-z candidates exhibit colder colours than their surroundings, consistent with redshifts z > 2, assuming a dust temperature of Txgal = 35 K and a spectral index of βxgal = 1.5. Exhibiting extremely high luminosities, larger than 1014L⊙, the PHZ objects may be made of multiple galaxies or clumps at high redshift, as suggested by a first statistical analysis based on a comparison with number count models. Furthermore, first follow-up observations obtained from optical to submillimetre wavelengths, which can be found in companion papers, have confirmed that this list consists of two distinct populations. A small fraction (around 3%) of the sources have been identified as strongly gravitationally lensed star-forming galaxies at redshift 2 to 4, while the vast majority of the PHZ sources appear as overdensities of dusty star-forming galaxies, having colours consistent with being at z > 2, and may be considered as proto-cluster candidates. The PHZ provides an original sample, which is complementary to the Planck Sunyaev-Zeldovich Catalogue (PSZ2); by extending the population of virialized massive galaxy clusters detected below z 1.5, the PHZ may contain

  3. The high redshift universe and cosmology

    Science.gov (United States)

    Hook, Isobel

    2013-12-01

    The ELTs, assisted by adaptive optics, will revolutionise observations of the high redshift universe. Using examples taken primarily from the science case of the E-ELT, this talk will cover prospects and requirements for studying distant galaxies and point sources at cosmological distances including gamma ray bursts, quasars and supernovae. The impact these observations will have on cosmology and our understanding of the early universe will be discussed.

  4. FeII/MgII Emission Line Ratio in High Redshift Quasars

    DEFF Research Database (Denmark)

    Dietrich, M.; Hamann, F.; Appenzeller, I.

    2003-01-01

    We present results of the analysis of near infrared spectroscopic observations of 6 high-redshift quasars (z > 4), emphasizing the measurement of the ultraviolet FeII/MgII emission line strength in order to estimate the beginning of intense star formation in the early universe. To investigate the...

  5. Radio-loud high-redshift protogalaxy canidates in Bootes

    Energy Technology Data Exchange (ETDEWEB)

    Croft, S; van Breugel, W; Brown, M J; de Vries, W; Dey, A; Eisenhardt, P; Jannuzi, B; Rottgering, H; Stanford, S A; Stern, D; Willner, S P

    2007-07-20

    We used the Near Infrared Camera (NIRC) on Keck I to obtain K{sub s}-band images of four candidate high-redshift radio galaxies selected using optical and radio data in the NOAO Deep Wide-Field Survey in Bootes. Our targets have 1.4 GHz radio flux densities greater than 1 mJy, but are undetected in the optical. Spectral energy distribution fitting suggests that three of these objects are at z > 3, with radio luminosities near the FR-I/FR-II break. The other has photometric redshift z{sub phot} = 1.2, but may in fact be at higher redshift. Two of the four objects exhibit diffuse morphologies in K{sub s}-band, suggesting that they are still in the process of forming.

  6. Observations of GRBs at high redshift.

    Science.gov (United States)

    Tanvir, Nial R; Jakobsson, Páll

    2007-05-15

    The extreme luminosity of gamma-ray bursts and their afterglows means they are detectable, in principle, to very high redshifts. Although the redshift distribution of gamma-ray bursts (GRBs) is difficult to determine, due to incompleteness of present samples, we argue that for Swift-detected bursts, the median redshift is between 2.5 and 3, with a few per cent probably at z>6. Thus, GRBs are potentially powerful probes of the era of reionization and the sources responsible for it. Moreover, it seems probable that they can provide constraints on the star-formation history of the Universe and may also help in the determination of the cosmological parameters.

  7. Quasar Elemental Abundances at High Redshifts

    DEFF Research Database (Denmark)

    Dietrich, M.; Hamann, F.; Shields, J. C.

    2003-01-01

    We examine rest-frame ultraviolet spectra of 70 high redshift quasars (z>3.5) to study the chemical enrichment history of the gas closely related to the quasars, and thereby estimate the epoch of first star formation. The fluxes of several ultraviolet emission lines were investigated within...... scale of t_evol = 0.5 - 0.8 Gyrs for the chemical enrichment of the gas, the first major star formation for quasars with z>=4 should have started at a redshift of z_f = 6 - 8, corresponding to an age of the universe of several 10^8 yrs (H_o = 65 km/s/Mpc, Omega_M = 0.3, Omega_Lambda = 0.7). We note...

  8. The potential of INTEGRAL for the detection of high redshift GRBs

    DEFF Research Database (Denmark)

    Gorosabel, J.; Lund, Niels; Brandt, Søren Kristian

    2004-01-01

    We discuss INTEGRAL's ability to detect a high redshift population of Gamma-Ray Bursts (GRBs) in comparison to other high-energy missions. Emphasis is placed on the study of the relative capabilities of IBIS on board INTEGRAL with respect to SWIFT and HETE 2 in detecting a high redshift population...... of GRBs. We conclude that, if the GRB rate is proportional to the star formation rate, INTEGRAL's ability to study GRBs are complementary to the ones of missions like SWIFT and HETE 2, devoted to prompt localisations of GRBs. Whereas SWIFT and HETE 2 would detect a higher number of GRBs than INTEGRAL......, IBIS might be able to detect high redshift (z greater than or similar to 7) GRBs, unreachable by SWIFT and HETE 2. We discuss the relevance of performing near-infrared (NIR) observations of the INTEGRAL GRBs and the strategy that large-class telescopes might follow....

  9. Galaxy luminosity function: evolution at high redshift

    Science.gov (United States)

    Martinet, N.; Durret, F.; Guennou, L.; Adami, C.

    2014-12-01

    There are some disagreements about the abundance of faint galaxies in high redshift clusters. DAFT/FADA (Dark energy American French Team) is a medium redshift (0.4

  10. Highly Accreting Quasars at High Redshift

    Directory of Open Access Journals (Sweden)

    Mary L. Martínez-Aldama

    2018-01-01

    Full Text Available We present preliminary results of a spectroscopic analysis for a sample of type 1 highly accreting quasars (L/LEdd ~ 1.0 at high redshift, z ~2–3. The quasars were observed with the OSIRIS spectrograph on the GTC 10.4 m telescope located at the Observatorio del Roque de los Muchachos in La Palma. The highly accreting quasars were identified using the 4D Eigenvector 1 formalism, which is able to organize type 1 quasars over a broad range of redshift and luminosity. The kinematic and physical properties of the broad line region have been derived by fitting the profiles of strong UV emission lines such as Aliiiλ1860, Siiii]λ1892 and Ciii]λ1909. The majority of our sources show strong blueshifts in the high-ionization lines and high Eddington ratios which are related with the productions of outflows. The importance of highly accreting quasars goes beyond a detailed understanding of their physics: their extreme Eddington ratio makes them candidates standard candles for cosmological studies.

  11. The radio core structure of the luminous infrared galaxy NGC 4418. A young clustered starburst revealed?

    Science.gov (United States)

    Varenius, E.; Conway, J. E.; Martí-Vidal, I.; Aalto, S.; Beswick, R.; Costagliola, F.; Klöckner, H.-R.

    2014-06-01

    Context. The galaxy NGC 4418 contains one of the most compact obscured nuclei within a luminous infrared galaxy (LIRG) in the nearby Universe. This nucleus contains a rich molecular gas environment and an unusually high ratio of infrared-to-radio luminosity (q-factor). The compact nucleus is powered by either a compact starburst or an active galactic nucleus (AGN). Aims: The aim of this study is to constrain the nature of the nuclear region (starburst or AGN) within NGC 4418 via very-high-resolution radio imaging. Methods: Archival data from radio observations using the European Very Long Baseline Interferometry Network (EVN) and Multi-Element Radio Linked Interferometer Network (MERLIN) interferometers are imaged. Sizes and flux densities are obtained by fitting Gaussian intensity distributions to the image. The average spectral index of the compact radio emission is estimated from measurements at 1.4 GHz and 5.0 GHz. Results: The nuclear structure of NGC 4418 visible with EVN and MERLIN consists of eight compact (104.8 K indicate that these compact features cannot be HII-regions. The complex morphology and inverted spectrum of the eight detected compact features is evidence against the hypothesis that an AGN alone is powering the nucleus of NGC 4418. The compact features could be super star clusters with intense star formation, and their associated free-free absorption could then naturally explain both their inverted radio spectrum and the low radio-to-IR ratio of the nucleus. The required star formation area density is extreme, however, and close to the limit of what can be observed in a well-mixed thermal/non-thermal plasma produced by star formation, and is also close to the limit of what can be physically sustained.

  12. Star formation and AGN activity in a sample of local luminous infrared galaxies through multiwavelength characterization

    Science.gov (United States)

    Herrero-Illana, Rubén; Pérez-Torres, Miguel Á.; Randriamanakoto, Zara; Alberdi, Antxon; Efstathiou, Andreas; Väisänen, Petri; Kankare, Erkki; Kool, Erik; Mattila, Seppo; Ramphul, Rajin; Ryder, Stuart

    2017-10-01

    Nuclear starbursts and active galactic nucleus (AGN) activity are the main heating processes in luminous infrared galaxies (LIRGs) and their relationship is fundamental to understand galaxy evolution. In this paper, we study the star formation and AGN activity of a sample of 11 local LIRGs imaged with subarcsecond angular resolution at radio (8.4 GHz) and near-infrared (2.2 μm) wavelengths. This allows us to characterize the central kpc of these galaxies with a spatial resolution of ≃100 pc. In general, we find a good spatial correlation between the radio and the near-IR emission, although radio emission tends to be more concentrated in the nuclear regions. Additionally, we use an Markov Chain Monte Carlo code to model their multiwavelength spectral energy distribution (SED) using template libraries of starburst, AGN and spheroidal/cirrus models, determining the luminosity contribution of each component, and finding that all sources in our sample are starburst-dominated, except for NGC 6926 with an AGN contribution of ≃64 per cent. Our sources show high star formation rates (40-167 M⊙ yr-1), supernova rates (0.4-2.0 SN yr-1) and similar starburst ages (13-29 Myr), except for the young starburst (9 Myr) in NGC 6926. A comparison of our derived star-forming parameters with estimates obtained from different IR and radio tracers shows an overall consistency among the different star formation tracers. AGN tracers based on mid-IR, high-ionization line ratios also show an overall agreement with our SED model fit estimates for the AGN. Finally, we use our wide-band Very Large Array observations to determine pixel-by-pixel radio spectral indices for all galaxies in our sample, finding a typical median value (α ≃ -0.8) for synchrotron-powered LIRGs.

  13. Spitzer study of an extreme tidal disruption event in a luminous infrared galaxy

    Science.gov (United States)

    Mattila, Seppo; Kool, Erik; Ryder, Stuart; Perez-Torres, Miguel; Kankare, Erkki; Reynolds, Thomas; Fraser, Morgan; Kotak, Rubina

    2017-10-01

    Observations of thermal emission from warm dust surrounding tidal disruption events (TDEs) are still very sparse. We propose short IRAC observations to follow the 3.6 and 4.5 um light curve evolution of an extreme TDE candidate in a nearby luminous infrared galaxy (LIRG) IRAS 23436+5257. Although LIRGs are locally a rare class of galaxies, they already appear to be over-abundant among TDE hosts. This event was discovered using adaptive optics (AO) assisted near-IR observations with the Keck telescope and is consistent with an extremely energetic TDE with much of its emission reprocessed by dense gas, and re-radiated at IR wavelengths by local dust. Combined with our already ongoing ground-based near-IR and multifrequency radio interferometric monitoring, we will be able to determine the nature of the event, its bolometric luminosity and the total radiated energy. Finally, events similar to the one in IRAS 23436+5257 would not be detectable by optical surveys nor ultraviolet or soft X-ray observations and could be just the tip of the iceberg of a hitherto missed TDE population which remains to be unveiled by the JWST.

  14. Mid-infrared properties of luminous infrared galaxies. II. Probing the dust and gas physics of the goals sample

    Energy Technology Data Exchange (ETDEWEB)

    Stierwalt, S.; Armus, L.; Diaz-Santos, T.; Marshall, J.; Haan, S.; Howell, J.; Murphy, E. J.; Inami, H.; Petric, A. O. [Spitzer Science Center, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Charmandaris, V. [Department of Physics, University of Crete, GR-71003 Heraklion (Greece); Evans, A. S. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Iwasawa, K. [INAF-Observatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy); Kim, D. C. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Rich, J. A. [The Observatories, Carnegie Institute of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Spoon, H. W. W. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); U, V., E-mail: sabrinas@virginia.edu [Department of Physics and Astronomy, University of California, Riverside, CA 92507 (United States)

    2014-08-01

    The Great Observatories All-sky LIRG Survey (GOALS) is a comprehensive, multiwavelength study of luminous infrared galaxies (LIRGs) in the local universe. Here, we present the results of a multi-component, spectral decomposition analysis of the low-resolution mid-infrared (MIR) Spitzer Infrared Spectrograph spectra from 5-38 μm of 244 LIRG nuclei. The detailed fits and high-quality spectra allow for characterization of the individual polycyclic aromatic hydrocarbon (PAH) features, warm molecular hydrogen emission, and optical depths for both silicate dust grains and water ices. We find that starbursting LIRGs, which make up the majority of the GOALS sample, are very consistent in their MIR properties (i.e., τ{sub 9.7μm}, τ{sub ice}, neon line ratios, and PAH feature ratios). However, as their EQW{sub 6.2{sub μm}} decreases, usually an indicator of an increasingly dominant active galactic nucleus (AGN), LIRGs cover a larger spread in these MIR parameters. The contribution from PAH emission to the total IR luminosity (L(PAH)/L(IR)) in LIRGs varies from 2%-29% and LIRGs prior to their first encounter show significantly higher L(PAH)/L(IR) ratios on average. We observe a correlation between the strength of the starburst (represented by IR8 = L{sub IR}/L{sub 8{sub μm}}) and the PAH fraction at 8 μm but no obvious link between IR8 and the 7.7 to 11.3 PAH ratio, suggesting that the fractional photodissociation region (PDR) emission, and not the overall grain properties, is associated with the rise in IR8 for galaxies off the starburst main sequence. We detect crystalline silicate features in ∼6% of the sample but only in the most obscure sources (s{sub 9.7{sub μm}} < –1.24). Ice absorption features are observed in ∼11% (56%) of GOALS LIRGs (ULIRGs) in sources with a range of silicate depths. Most GOALS LIRGs have L(H{sub 2})/L(PAH) ratios elevated above those observed for normal star-forming galaxies and exhibit a trend for increasing L(H{sub 2})/L

  15. LOCAL LUMINOUS INFRARED GALAXIES. III. CO-EVOLUTION OF BLACK HOLE GROWTH AND STAR FORMATION ACTIVITY?

    Energy Technology Data Exchange (ETDEWEB)

    Alonso-Herrero, Almudena; Hernan-Caballero, Antonio [Instituto de Fisica de Cantabria, CSIC-Universidad de Cantabria, E-39005 Santander (Spain); Pereira-Santaella, Miguel [Istituto di Astrofisica e Planetologia Spaziali, INAF-IAPS, I-00133 Rome (Italy); Rieke, George H. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Diamond-Stanic, Aleksandar M. [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA 92093 (United States); Wang Yiping [National Astronomical Observatories, Chaoyang District, Beijing 100012 (China); Rigopoulou, Dimitra [Astrophysics Department, University of Oxford, Oxford OX1 3RH (United Kingdom)

    2013-03-10

    Local luminous infrared (IR) galaxies (LIRGs) have both high star formation rates (SFR) and a high AGN (Seyfert and AGN/starburst composite) incidence. Therefore, they are ideal candidates to explore the co-evolution of black hole (BH) growth and star formation (SF) activity, not necessarily associated with major mergers. Here, we use Spitzer/IRS spectroscopy of a complete volume-limited sample of local LIRGs (distances of <78 Mpc). We estimate typical BH masses of 3 Multiplication-Sign 10{sup 7} M{sub Sun} using [Ne III] 15.56 {mu}m and optical [O III] {lambda}5007 gas velocity dispersions and literature stellar velocity dispersions. We find that in a large fraction of local LIRGs, the current SFR is taking place not only in the inner nuclear {approx}1.5 kpc region, as estimated from the nuclear 11.3 {mu}m PAH luminosities, but also in the host galaxy. We next use the ratios between the SFRs and BH accretion rates (BHAR) to study whether the SF activity and BH growth are contemporaneous in local LIRGs. On average, local LIRGs have SFR to BHAR ratios higher than those of optically selected Seyferts of similar active galactic nucleus (AGN) luminosities. However, the majority of the IR-bright galaxies in the revised-Shapley-Ames Seyfert sample behave like local LIRGs. Moreover, the AGN incidence tends to be higher in local LIRGs with the lowest SFRs. All of this suggests that in local LIRGs there is a distinct IR-bright star-forming phase taking place prior to the bulk of the current BH growth (i.e., AGN phase). The latter is reflected first as a composite and then as a Seyfert, and later as a non-LIRG optically identified Seyfert nucleus with moderate SF in its host galaxy.

  16. Massive Star Cluster Formation and Destruction in Luminous Infrared Galaxies in GOALS

    Science.gov (United States)

    Linden, S. T.; Evans, A. S.; Rich, J.; Larson, K. L.; Armus, L.; Díaz-Santos, T.; Privon, G. C.; Howell, J.; Inami, H.; Kim, D.-C.; Chien, L.-H.; Vavilkin, T.; Mazzarella, J. M.; Modica, F.; Surace, J. A.; Manning, S.; Abdullah, A.; Blake, A.; Yarber, A.; Lambert, T.

    2017-07-01

    We present the results of a Hubble Space Telescope ACS/HRC FUV, ACS/WFC optical study into the cluster populations of a sample of 22 Luminous Infrared Galaxies in the Great Observatories All-Sky LIRG Survey. Through integrated broadband photometry, we have derived ages and masses for a total of 484 star clusters contained within these systems. This allows us to examine the properties of star clusters found in the extreme environments of LIRGs relative to lower luminosity star-forming galaxies in the local universe. We find that by adopting a Bruzual & Charlot simple stellar population model and Salpeter initial mass function, the age distribution of the clusters declines as {dN}/dτ ={τ }-0.9+/-0.3, consistent with the age distribution derived for the Antennae Galaxies, and interpreted as evidence for rapid cluster disruption occurring in the strong tidal fields of merging galaxies. The large number of {10}6 {M}⊙ young clusters identified in the sample also suggests that LIRGs are capable of producing more high-mass clusters than what is observed to date in any lower luminosity star-forming galaxy in the local universe. The observed cluster mass distribution of {dN}/{dM}={M}-1.95+/-0.11 is consistent with the canonical -2 power law used to describe the underlying initial cluster mass function (ICMF) for a wide range of galactic environments. We interpret this as evidence against mass-dependent cluster disruption, which would flatten the observed CMF relative to the underlying ICMF distribution.

  17. Galaxy Merger Candidates in High-redshift Cluster Environments

    Science.gov (United States)

    Delahaye, A. G.; Webb, T. M. A.; Nantais, J.; DeGroot, A.; Wilson, G.; Muzzin, A.; Yee, H. K. C.; Foltz, R.; Noble, A. G.; Demarco, R.; Tudorica, A.; Cooper, M. C.; Lidman, C.; Perlmutter, S.; Hayden, B.; Boone, K.; Surace, J.

    2017-07-01

    We compile a sample of spectroscopically and photometrically selected cluster galaxies from four high-redshift galaxy clusters (1.59Red-Sequence Cluster Survey (SpARCS), and a comparison field sample selected from the UKIDSS Deep Survey. Using near-infrared imaging from the Hubble Space Telescope, we classify potential mergers involving massive ({M}* ≥slant 3× {10}10 {M}⊙ ) cluster members by eye, based on morphological properties such as tidal distortions, double nuclei, and projected near neighbors within 20 kpc. With a catalog of 23 spectroscopic and 32 photometric massive cluster members across the four clusters and 65 spectroscopic and 26 photometric comparable field galaxies, we find that after taking into account contamination from interlopers, {11.0}-5.6+7.0 % of the cluster members are involved in potential mergers, compared to {24.7}-4.6+5.3 % of the field galaxies. We see no evidence of merger enhancement in the central cluster environment with respect to the field, suggesting that galaxy-galaxy merging is not a stronger source of galaxy evolution in cluster environments compared to the field at these redshifts.

  18. The High-Redshift Clusters Occupied by Bent Radio AGN (COBRA) Survey

    Science.gov (United States)

    Paterno-Mahler, Rachel; Blanton, Elizabeth L.; Wing, Joshua; Ashby, M. L. N.; Brodwin, Mark; Golden-Marx, Emmet

    The number of confirmed, high-redshift galaxy clusters is very low compared to the number of well-studied clusters nearby. Bent, double-lobed radio sources are frequently found in galaxy clusters, and thus can be used as tracers for efficiently locating high-redshift clusters. Using our Spitzer Snapshot Survey, we have identified approximately 300 potential new clusters with redshifts 0.7 COBRA) survey. We have created color-magnitude diagrams using infrared and optical data. Using the colors of the radio source host and the red sequence we can estimate redshifts for our clusters, as well as examine the evolution of the cluster galaxies over a large range of cosmic time.

  19. [Ultra] luminous infrared galaxies selected at 90 μm in the AKARI deep field: a study of AGN types contributing to their infrared emission

    Science.gov (United States)

    Małek, K.; Bankowicz, M.; Pollo, A.; Buat, V.; Takeuchi, T. T.; Burgarella, D.; Goto, T.; Malkan, M.; Matsuhara, H.

    2017-02-01

    Aims: The aim of this work is to characterize physical properties of ultra luminous infrared galaxies (ULIRGs) and luminous infrared galaxies (LIRGs) detected in the far-infrared (FIR) 90 μm band in the AKARI Deep Field-South (ADF-S) survey. In particular, we want to estimate the active galactic nucleus (AGN) contribution to the LIRGs and ULIRGs' infrared emission and which types of AGNs are related to their activity. Methods: We examined 69 galaxies at redshift ≥0.05 detected at 90 μm by the AKARI satellite in the ADF-S, with optical counterparts and spectral coverage from the ultraviolet to the FIR. We used two independent spectral energy distribution fitting codes: one fitting the SED from FIR to FUV (CIGALE) (we use the results from CIGALE as a reference) and gray-body + power spectrum fit for the infrared part of the spectra (CMCIRSED) in order to identify a subsample of ULIRGs and LIRGs, and to estimate their properties. Results: Based on the CIGALE SED fitting, we have found that LIRGs and ULIRGs selected at the 90 μm AKARI band compose 56% of our sample (we found 17 ULIRGs and 22 LIRGs, spanning over the redshift range 0.06 ADF-S LIRGs and ULIRGs indicate that these relations are shaped by the dust mass and not by the increased dust heating. Conclusions: We conclude that LIRGs contain Type 1, Type 2, and intermediate types of AGNs, with an AGN contribution to the mid infrared emission at the median level of 13 ± 3%, whereas the majority of ULIRGs contain Type 2 AGNs, with a median AGN fraction equal to 19 ± 8%. Full Table A.1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/598/A1

  20. High Redshift Lyman-α Hunt

    DEFF Research Database (Denmark)

    Kochiashvili, Ia

    .85.I used the near-infrared data from NB1060, Y and J filters to perform colour-colourand colour-magnitude selections. With the broad-band data from CANDELS catalogue,I performed SED fitting and derived photometric redshifts and other physical propertiesfor the candidate emission-line galaxies....... Significant differences between the two selectionmethods have been found. The colour-colour selection method, tends to pick galaxieswith high colour excess and can leave some strong emission-line candidates with relativelylower colour excess out of the sample. The populations of selected galaxies can also...... bevery biased. The colour-magnitude selection method picks not only “normal” galaxies,but also starburst ones.I investigated the physical properties and colour indices for the selected galaxies,obtaining the following results. I) Stellar masses for narrow-band selected galaxies arefound...

  1. A High Redshift Survey of Lyman Limit Systems

    Science.gov (United States)

    Beltz, Hayley; Jorgenson, Regina A.; Rafelski, Marc

    2018-01-01

    Lyman Limit Systems (LLSs), a class of quasar absorption line system detected towards background quasars, are ubiquitous in quasar spectra and provide a crucial tool for understanding high redshift galaxy formation and evolution. At moderate neutral hydrogen (HI) column densities, 1017.5complement to these previous studies, we present a survey of LLSs in a sample of twenty-six, high redshift (z>5) quasars with VLT/X-Shooter spectra. These high redshift systems unlock information about the universe during its first few gigayears. We calculate the number of systems per unit redshift, l(X), at z >4.4, extending the redshift evolution of LLSs presented in Fumagalli et al. (2015). For those systems with associated metal line absorption, we provide an estimate of the LLSs metallicity. This project was supported in part by the NSF REU grant AST-1358980 and by the Nantucket Maria Mitchell Association.

  2. The Clustering of High-Redshift (2.9 < z < 5.4) Quasars in SDSS Stripe 82

    Science.gov (United States)

    Timlin, John; Ross, Nicolas; Richards, Gordon; Myers, Adam; Bauer, Franz Erik; Lacy, Mark; Schneider, Donald; Wollack, Edward; Zakamska, Nadia

    2018-01-01

    We present the data from the Spitzer IRAC Equatorial Survey (SpIES) along with our first high-redshift (2.9SpIES is a mid-infrared survey covering ~100 square degrees of the Sloan Digital Sky Survey (SDSS) Stripe 82 (S82) field. The SpIES field is optimally located to overlap with the optical data from SDSS and to complement the area of the pre-existing Spitzer data from the Spitzer-HETDEX Exploratory Large-area (SHELA) survey, which adds ~20 square degrees of infrared coverage on S82. SpIES probes magnitudes significantly fainter than WISE; depth that is crucial to detect faint, high-redshift quasars. Using the infrared data from SpIES and SHELA, and the deep optical data from SDSS, we employ multi-dimensional empirical selection algorithms to identify high-redshift quasar candidates in this field. We then combine these candidates with spectroscopically confirmed high-redshift quasars and measure the angular correlation function. Using these results, we compute the linear bias to try to constrain quasar feedback models akin to those in Hopkins et al. 2007.

  3. Infrared signature of transient luminous events in the middle atmosphere simulated for a limb line of sight observation

    Science.gov (United States)

    Payan, Sebastien; Romand, Frederic; Laurence, Croizé

    2017-04-01

    Transient Luminous Events (TLE) are electrical and optical events which occurs above thunderstorms. Their occurrence is closely linked with the lightning activity below thunderstorms. TLEs are observed from the base of the stratosphere to the thermosphere (15 - 110 km). They are a very brief phenomenon which lasts from 1 to 300 milliseconds. At a worldwide scale, some to some tenths of TLEs occurs each minute. The energy deposition, about some tenths of megajoules, is able to ionize, dissociate and excite the molecules of the atmosphere. Then, a phase of recombination and relaxation starts. The interest of their study is multiple. In atmospheric chemistry we know that lightening are important sources of NOx in the troposphere, which indirectly influence the concentrations of O3 and OH. We wonder what could be the chemical effects of TLEs in the stratosphere and mesosphere. Experimentally, the HALESIS (High altitude Luminous Events Studied by Infrared Spectro-imagery) project aims to load a spectro-imager in a stratospheric balloon in order to measure atmospheric radiances in the moments following the electrical discharge of a TLE and then, to estimate the concentration of some components of interest (CO2, NO, O3, OH…) with spectrum inversions. In a Defense point of view, some airborne detection or guiding devices are equipped with infrared sensors, which may be disturbed by the TLEs infrared signal. The objective is to provide a tool which will describe the TLE phenomenon from the electric discharge to the detection threw an infrared sensor. To achieve this work we first compute the Non Local Thermodynamic Equilibrium population of a background atmosphere with the code SAMM2. The starting atmosphere comes from the Whole Atmosphere community Climate Model (WACCM). Then, we apply a TLE perturbation to a region of the background atmosphere. To do so we compute the plasma and atmospheric chemistry consecutive to the discharge of a TLE with the codes BOLSIG+ and

  4. UV Continuum Slope and Dust Obscuration from z ~ 6 to z ~ 2: The Star Formation Rate Density at High Redshift

    Science.gov (United States)

    Bouwens, R. J.; Illingworth, G. D.; Franx, M.; Chary, R.-R.; Meurer, G. R.; Conselice, C. J.; Ford, H.; Giavalisco, M.; van Dokkum, P.

    2009-11-01

    We provide a systematic measurement of the rest-frame UV continuum slope β over a wide range in redshift (z ~ 2-6) and rest-frame UV luminosity (0.1 L* z = 3 to 2 L* z = 3) to improve estimates of the star formation rate (SFR) density at high redshift. We utilize the deep optical and infrared data (Advanced Camera for Surveys/NICMOS) over the Chandra Deep Field-South and Hubble Deep Field-North Great Observatories Origins Deep Survey fields, as well as the UDF for our primary UBVi "dropout" Lyman Break Galaxy sample. We also use strong lensing clusters to identify a population of very low luminosity, high-redshift dropout galaxies. We correct the observed distributions for both selection biases and photometric scatter. We find that the UV-continuum slope of the most luminous galaxies is substantially redder at z ~ 2-4 than it is at z ~ 5-6 (from ~-2.4 at z ~ 6 to ~-1.5 at z ~ 2). Lower luminosity galaxies are also found to be bluer than higher luminosity galaxies at z ~ 2.5 and z ~ 4. We do not find a large number of galaxies with β's as red as -1 in our dropout selections at z ~ 4, and particularly at z gsim 5, even though such sources could be readily selected from our data (and also from Balmer Break Galaxy searches at z ~ 4). This suggests that star-forming galaxies at z gsim 5 almost universally have very blue UV-continuum slopes, and that there are not likely to be a substantial number of dust-obscured galaxies at z gsim 5 that are missed in "dropout" searches. Using the same relation between UV-continuum slope and dust extinction as has been found to be appropriate at both z ~ 0 and z ~ 2, we estimate the average dust extinction of galaxies as a function of redshift and UV luminosity in a consistent way. As expected, we find that the estimated dust extinction increases substantially with cosmic time for the most UV luminous galaxies, but remains small (lsim2 times) at all times for lower luminosity galaxies. Because these same lower luminosity galaxies

  5. The intergalactic medium near high-redshift galaxies

    NARCIS (Netherlands)

    Rakic, Olivera

    2012-01-01

    Over the past 15 years, the field of extragalactic astronomy has pushed to high redshift and our knowledge of natal galaxies has grown dramatically. Galaxies are now routinely detected at redshifts z ! 6−7 (e.g. Bouwens et al. 2010; Labb´e et al. 2010; Oesch et al. 2010; Bouwens et al. 2011;

  6. Discerning dark energy models with high redshift standard candles

    Science.gov (United States)

    Andersen, P.; Hjorth, J.

    2017-12-01

    Following the success of type Ia supernovae in constraining cosmologies at lower redshift (z ≲ 2), effort has been spent determining if a similarly useful standardizable candle can be found at higher redshift. In this work, we determine the largest possible magnitude discrepancy between a constant dark energy ΛCDM cosmology and a cosmology in which the equation of state w(z) of dark energy is a function of redshift for high redshift standard candles (z ≳ 2). We discuss a number of popular parametrizations of w(z) with two free parameters, wzCDM cosmologies, including the Chevallier-Polarski-Linder and generalization thereof, nCPL, as well as the Jassal-Bagla-Padmanabhan parametrization. For each of these parametrizations, we calculate and find the extrema of Δμ, the difference between the distance modulus of a wzCDM cosmology and a fiducial ΛCDM cosmology as a function of redshift, given 68 per cent likelihood constraints on the parameters P = (Ωm, 0, w0, wa). The parameters are constrained using cosmic microwave background, baryon acoustic oscillations and type Ia supernovae data using CosmoMC. We find that none of the tested cosmologies can deviate more than 0.05 mag from the fiducial ΛCDM cosmology at high redshift, implying that high redshift standard candles will not aid in discerning between the wzCDM cosmology and the fiducial ΛCDM cosmology. Conversely, this implies that if high redshift standard candles are found to be in disagreement with ΛCDM at high redshift, then this is a problem not only for ΛCDM but for the entire family of wzCDM cosmologies.

  7. The X-Ray and Mid-infrared Luminosities in Luminous Type 1 Quasars

    Science.gov (United States)

    Chen, Chien-Ting J.; Hickox, Ryan C.; Goulding, Andrew D.; Stern, Daniel; Assef, Roberto; Kochanek, Christopher S.; Brown, Michael J. I.; Harrison, Chris M.; Hainline, Kevin N.; Alberts, Stacey; Alexander, David M.; Brodwin, Mark; Del Moro, Agnese; Forman, William R.; Gorjian, Varoujan; Jones, Christine; Murray, Stephen S.; Pope, Alexandra; Rovilos, Emmanouel

    2017-03-01

    Several recent studies have reported different intrinsic correlations between the active galactic nucleus (AGN) mid-IR luminosity ({L}{MIR}) and the rest-frame 2-10 keV luminosity (L X) for luminous quasars. To understand the origin of the difference in the observed {L}{{X}}{--}{L}{MIR} relations, we study a sample of 3247 spectroscopically confirmed type 1 AGNs collected from Boötes, XMM-COSMOS, XMM-XXL-North, and the Sloan Digital Sky Survey quasars in the Swift/XRT footprint spanning over four orders of magnitude in luminosity. We carefully examine how different observational constraints impact the observed {L}{{X}}{--}{L}{MIR} relations, including the inclusion of X-ray-nondetected objects, possible X-ray absorption in type 1 AGNs, X-ray flux limits, and star formation contamination. We find that the primary factor driving the different {L}{{X}}{--}{L}{MIR} relations reported in the literature is the X-ray flux limits for different studies. When taking these effects into account, we find that the X-ray luminosity and mid-IR luminosity (measured at rest-frame 6 μ {{m}}, or {L}6μ {{m}}) of our sample of type 1 AGNs follow a bilinear relation in the log-log plane: {log}{L}{{X}}=(0.84+/- 0.03)× {log}{L}6μ {{m}}/{10}45 erg s-1 + (44.60 ± 0.01) for {L}6μ {{m}}< {10}44.79 erg s-1, and {log}{L}{{X}}=(0.40+/- 0.03)× {log}{L}6μ {{m}}/{10}45 erg s-1 + (44.51 ± 0.01) for {L}6μ {{m}} ≥slant {10}44.79 erg s-1. This suggests that the luminous type 1 quasars have a shallower {L}{{X}}{--}{L}6μ {{m}} correlation than the approximately linear relations found in local Seyfert galaxies. This result is consistent with previous studies reporting a luminosity-dependent {L}{{X}}{--}{L}{MIR} relation and implies that assuming a linear {L}{{X}}{--}{L}6μ {{m}} relation to infer the neutral gas column density for X-ray absorption might overestimate the column densities in luminous quasars.

  8. Submillimeter H2O and H2O+emission in lensed ultra- and hyper-luminous infrared galaxies at z 2-4

    NARCIS (Netherlands)

    Yang, C.; Omont, A.; Beelen, A.; González-Alfonso, E.; Neri, R.; Gao, Y.; van der Werf, P.; Weiß, A.; Gavazzi, R.; Falstad, N.; Baker, A. J.; Bussmann, R. S.; Cooray, A.; Cox, P.; Dannerbauer, H.; Dye, S.; Guélin, M.; Ivison, R.; Krips, M.; Lehnert, M.; Michałowski, M. J.; Riechers, D. A.; Spaans, M.; Valiante, E.

    2016-01-01

    We report rest-frame submillimeter H2O emission line observations of 11 ultra- or hyper-luminous infrared galaxies (ULIRGs or HyLIRGs) at z 2-4 selected among the brightest lensed galaxies discovered in the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS). Using the IRAM NOrthern

  9. High-Redshift galaxies light from the early universe

    CERN Document Server

    Appenzeller, Immo

    2008-01-01

    This book provides a comprehensive account of the scientific results on high-redshift galaxies accumulated during the past ten years. Apart from summarizing and critically discussing the wealth of observational data, the observational methods which made it possible to study these very distant and extremely faint objects are described in detail. Moreover, the technical feasibilities and physical limitations for existing and for future ground-based and space-based telescopes are discussed. Thus, apart from summarizing the knowledge accumulated so far, the book is designed as a tool for planning future observational and instrumental programs and projects. In view of the potential importance of the observational results of the high-redshift universe for basic physics the book is written for astronomers as well as for physicists without prior astronomical knowledge. For this purpose it contains introductory chapters describing the basic concepts and notations used in modern astronomy and a brief overview of the pr...

  10. Detectability of Gravitational Waves from High-Redshift Binaries.

    Science.gov (United States)

    Rosado, Pablo A; Lasky, Paul D; Thrane, Eric; Zhu, Xingjiang; Mandel, Ilya; Sesana, Alberto

    2016-03-11

    Recent nondetection of gravitational-wave backgrounds from pulsar timing arrays casts further uncertainty on the evolution of supermassive black hole binaries. We study the capabilities of current gravitational-wave observatories to detect individual binaries and demonstrate that, contrary to conventional wisdom, some are, in principle, detectable throughout the Universe. In particular, a binary with rest-frame mass ≳10^{10}M_{⊙} can be detected by current timing arrays at arbitrarily high redshifts. The same claim will apply for less massive binaries with more sensitive future arrays. As a consequence, future searches for nanohertz gravitational waves could be expanded to target evolving high-redshift binaries. We calculate the maximum distance at which binaries can be observed with pulsar timing arrays and other detectors, properly accounting for redshift and using realistic binary waveforms.

  11. Photometry of High-Redshift Gravitationally Lensed Type Ia Supernovae

    Science.gov (United States)

    Haynie, Annastasia

    2018-01-01

    Out of more than 1100 well-identified Type Ia Supernovae, only roughly 10 of them are at z> 1.5. High redshift supernovae are hard to detect but this is made easier by taking advantage of the effects of gravitational lensing, which magnifies objects in the background field of massive galaxy clusters. Supernova Nebra (z= ~1.8), among others, was discovered during observations taken as part of the RELICS survey, which focused on fields of view that experience strong gravitational lensing effects. SN Nebra, which sits behind galaxy cluster Abell 1763, is magnified and therefore appears closer and easier to see than with HST alone. Studying high-redshift supernovae like SN Nebra is an important step towards creating cosmological models that accurately describe the behavior of dark energy in the early Universe. Recent efforts have been focused on improving photometry and the building and fitting of preliminary light curves.

  12. The high redshift Integrated Sachs-Wolfe effect

    Science.gov (United States)

    Xia, Jun-Qing; Viel, Matteo; Baccigalupi, Carlo; Matarrese, Sabino

    2009-09-01

    In this paper we rely on the quasar (QSO) catalog of the Sloan Digital Sky Survey Data Release Six (SDSS DR6) of about one million photometrically selected QSOs to compute the Integrated Sachs-Wolfe (ISW) effect at high redshift, aiming at constraining the behavior of the expansion rate and thus the behaviour of dark energy at those epochs. This unique sample significantly extends previous catalogs to higher redshifts while retaining high efficiency in the selection algorithm. We compute the auto-correlation function (ACF) of QSO number density from which we extract the bias and the stellar contamination. We then calculate the cross-correlation function (CCF) between QSO number density and Cosmic Microwave Background (CMB) temperature fluctuations in different subsamples: at high z > 1.5 and low z analysis. We find an overall evidence for a cross-correlation different from zero at the 2.7 σ level, while this evidence drops to 1.5 σ at z > 1.5. We focus on the capabilities of the ISW to constrain the behaviour of the dark energy component at high redshift both in the Λ CDM and Early Dark Energy cosmologies, when the dark energy is substantially unconstrained by observations. At present, the inclusion of the ISW data results in a poor improvement compared to the obtained constraints from other cosmological datasets. We study the capabilities of future high-redshift QSO survey and find that the ISW signal can improve the constraints on the most important cosmological parameters derived from Planck CMB data, including the high redshift dark energy abundance, by a factor ~ 1.5.

  13. Far-infrared emission in luminous quasars accompanied by nuclear outflows

    Science.gov (United States)

    Maddox, Natasha; Jarvis, M. J.; Banerji, M.; Hewett, P. C.; Bourne, N.; Dunne, L.; Dye, S.; Eales, S.; Furlanetto, C.; Maddox, S. J.; Smith, M. W. L.; Valiante, E.

    2017-09-01

    Combining large-area optical quasar surveys with the new far-infrared (FIR) Herschel-ATLAS Data Release 1, we search for an observational signature associated with the minority of quasars possessing bright FIR luminosities. We find that FIR-bright quasars show broad C IV emission-line blueshifts in excess of that expected from the optical luminosity alone, indicating particularly powerful nuclear outflows. The quasars show no signs of having redder optical colours than the general ensemble of optically selected quasars, ruling out differences in line-of-sight dust within the host galaxies. We postulate that these objects may be caught in a special evolutionary phase, with unobscured, high black hole accretion rates and correspondingly strong nuclear outflows. The high FIR emission found in these objects is then either a result of star formation related to the outflow, or is due to dust within the host galaxy illuminated by the quasar. We are thus directly witnessing coincident small-scale nuclear processes and galaxy-wide activity, commonly invoked in galaxy simulations that rely on feedback from quasars to influence galaxy evolution.

  14. Short-term optical variability of high-redshift QSO's

    OpenAIRE

    Bachev, R.; Strigachev, A.; Semkov, E.

    2004-01-01

    This paper presents results of a search for short-term variability in the optical band of selected high-luminosity, high-redshift radio-quiet quasars. Each quasar has been monitored typically for 2 - 4 hours with a time resolution of 2 - 5 minutes and a photometric accuracy of about 0.01 - 0.02 mag. Due to the significant redshift (z>2), the covered wavelength range falls into the UV region (typically 1500 - 2500A). We found no statistical evidence for any continuum variations larger than 0.0...

  15. MID-INFRARED ATOMIC FINE-STRUCTURE EMISSION-LINE SPECTRA OF LUMINOUS INFRARED GALAXIES: SPITZER/IRS SPECTRA OF THE GOALS SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Inami, H. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Armus, L.; Stierwalt, S.; Díaz-Santos, T.; Surace, J.; Howell, J.; Marshall, J. [Spitzer Science Center, California Institute of Technology, CA 91125 (United States); Charmandaris, V. [Department of Physics and Institute of Theoretical and Computational Physics, University of Crete, GR-71003 Heraklion (Greece); Groves, B. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Kewley, L. [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Petric, A. [Department of Astronomy, California Institute of Technology, MS 320-47, Pasadena, CA 91125 (United States); Rich, J. [The Observatories, Carnegie Institute of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Haan, S. [CSIRO Astronomy and Space Science, Marsfield, NSW 2122 (Australia); Evans, A. S. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Mazzarella, J.; Lord, S. [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Appleton, P. [NASA Herschel Science Center, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Spoon, H. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Frayer, D. [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944 (United States); Matsuhara, H., E-mail: inami@noao.edu [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (Japan); and others

    2013-11-10

    We present the data and our analysis of mid-infrared atomic fine-structure emission lines detected in Spitzer/Infrared Spectrograph high-resolution spectra of 202 local Luminous Infrared Galaxies (LIRGs) observed as part of the Great Observatories All-sky LIRG Survey (GOALS). We readily detect emission lines of [S IV], [Ne II], [Ne V], [Ne III], [S III]{sub 18.7{sub μm}}, [O IV], [Fe II], [S III]{sub 33.5{sub μm}}, and [Si II]. More than 75% of these galaxies are classified as starburst-dominated sources in the mid-infrared, based on the [Ne V]/[Ne II] line flux ratios and equivalent width of the 6.2 μm polycyclic aromatic hydrocarbon feature. We compare ratios of the emission-line fluxes to those predicted from stellar photo-ionization and shock-ionization models to constrain the physical and chemical properties of the gas in the starburst LIRG nuclei. Comparing the [S IV]/[Ne II] and [Ne III]/[Ne II] line ratios to the Starburst99-Mappings III models with an instantaneous burst history, the emission-line ratios suggest that the nuclear starbursts in our LIRGs have ages of 1-4.5 Myr, metallicities of 1-2 Z{sub ☉}, and ionization parameters of 2-8 × 10{sup 7} cm s{sup –1}. Based on the [S III]{sub 33.5{sub μm}}/[S III]{sub 18.7{sub μm}} ratios, the electron density in LIRG nuclei is typically one to a few hundred cm{sup –3}, with a median electron density of ∼300 cm{sup –3}, for those sources above the low density limit for these lines. We also find that strong shocks are likely present in 10 starburst-dominated sources of our sample. A significant fraction of the GOALS sources (80) have resolved neon emission-line profiles (FWHM ≥600 km s{sup –1}) and five show clear differences in the velocities of the [Ne III] or [Ne V] emission lines, relative to [Ne II], of more than 200 km s{sup –1}. Furthermore, six starburst and five active galactic nucleus dominated LIRGs show a clear trend of increasing line width with ionization potential

  16. Estimating Luminosity Function Constraints from High-Redshift Galaxy Surveys

    Science.gov (United States)

    Robertson, Brant E.

    2010-04-01

    The installation of the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) will revolutionize the study of high-redshift galaxy populations. Initial observations of the HST Ultra Deep Field (UDF) have yielded multiple z >~ 7 dropout candidates. Supplemented by the GOODS Early Release Science (ERS) and further UDF pointings, these data will provide crucial information about the most distant known galaxies. However, achieving tight constraints on the z ~ 7 galaxy luminosity function (LF) will require even more ambitious photometric surveys. Using a Fisher matrix approach to fully account for Poisson and cosmic sample variance, as well as covariances in the data, we estimate the uncertainties on LF parameters achieved by surveys of a given area and depth. Applying this method to WFC3 z ~ 7 dropout galaxy samples, we forecast the LF parameter uncertainties for a variety of model surveys. We demonstrate that performing a wide area (~1 deg2) survey to H AB ~ 27 depth or increasing the UDF depth to H AB ~ 30 provides excellent constraints on the high-z LF when combined with the existing Ultradeep Field Guest Observation and GOODS ERS data. We also show that the shape of the matter power spectrum may limit the possible gain of splitting wide area (gsim0.5 deg2) high-redshift surveys into multiple fields to probe statistically independent regions; the increased rms density fluctuations in smaller volumes mostly offset the improved variance gained from independent samples.

  17. Dark matter annihilation in the circumgalactic medium at high redshifts

    Science.gov (United States)

    Schön, S.; Mack, K. J.; Wyithe, J. S. B.

    2018-03-01

    Annihilating dark matter (DM) models offer promising avenues for future DM detection, in particular via modification of astrophysical signals. However, when modelling such potential signals at high redshift, the emergence of both DM and baryonic structure, as well as the complexities of the energy transfer process, needs to be taken into account. In the following paper, we present a detailed energy deposition code and use this to examine the energy transfer efficiency of annihilating DM at high redshift, including the effects on baryonic structure. We employ the PYTHIA code to model neutralino-like DM candidates and their subsequent annihilation products for a range of masses and annihilation channels. We also compare different density profiles and mass-concentration relations for 105-107 M⊙ haloes at redshifts 20 and 40. For these DM halo and particle models, we show radially dependent ionization and heating curves and compare the deposited energy to the haloes' gravitational binding energy. We use the `filtered' annihilation spectra escaping the halo to calculate the heating of the circumgalactic medium and show that the mass of the minimal star-forming object is increased by a factor of 2-3 at redshift 20 and 4-5 at redshift 40 for some DM models.

  18. GOODS-HERSCHEL MEASUREMENTS OF THE DUST ATTENUATION OF TYPICAL STAR-FORMING GALAXIES AT HIGH REDSHIFT: OBSERVATIONS OF ULTRAVIOLET-SELECTED GALAXIES AT z {approx} 2

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, N.; Dickinson, M.; Kartaltepe, J. [National Optical Astronomy Observatory, 950 N Cherry Ave, Tucson, AZ 85719 (United States); Elbaz, D.; Daddi, E.; Magdis, G.; Aussel, H.; Dannerbauer, H.; Dasyra, K.; Hwang, H. S. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Universite Paris Diderot, CE-Saclay, F-91191, Gif-sur-Yvette (France); Morrison, G. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Giavalisco, M. [Astronomy Department, University of Massachusetts, Amherst, Amherst, MA 01003 (United States); Ivison, R. [UK Astronomy Technology Centre, Science and Technology Facilities Council, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Papovich, C. [Department of Physics and Astronomy, Texas A and M University, College Station, TX 77845 (United States); Scott, D. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Buat, V.; Burgarella, D. [Laboratoire d' Astrophysique de Marseille, OAMP, Universite Aix-Marseille, CNRS, 38 Rue Frederic Joliot-Curie, 13388 Marseille Cedex 13 (France); Charmandaris, V. [Department of Physics and Institute of Theoretical and Computational Physics, University of Crete, GR-71003, Heraklion (Greece); Murphy, E. [Spitzer Science Center, MC 314-6, California Institute of Technology, Pasadena, CA 91125 (United States); Altieri, B. [Herschel Science Centre, European Space Astronomy Centre, Villanueva de la Canada, 28691 Madrid (Spain); and others

    2012-01-10

    We take advantage of the sensitivity and resolution of the Herschel Space Observatory at 100 and 160 {mu}m to directly image the thermal dust emission and investigate the infrared luminosities (L{sub IR}) and dust obscuration of typical star-forming (L*) galaxies at high redshift. Our sample consists of 146 UV-selected galaxies with spectroscopic redshifts 1.5 {<=} z{sub spec} < 2.6 in the GOODS-North field. Supplemented with deep Very Large Array and Spitzer imaging, we construct median stacks at the positions of these galaxies at 24, 100, and 160 {mu}m, and 1.4 GHz. The comparison between these stacked fluxes and a variety of dust templates and calibrations implies that typical star-forming galaxies with UV luminosities L{sub UV} {approx}> 10{sup 10} L{sub Sun} at z {approx} 2 are luminous infrared galaxies with a median L{sub IR} = (2.2 {+-} 0.3) Multiplication-Sign 10{sup 11} L{sub Sun }. Their median ratio of L{sub IR} to rest-frame 8 {mu}m luminosity (L{sub 8}) is L{sub IR}/L{sub 8} = 8.9 {+-} 1.3 and is Almost-Equal-To 80% larger than that found for most star-forming galaxies at z {approx}< 2. This apparent redshift evolution in the L{sub IR}/L{sub 8} ratio may be tied to the trend of larger infrared luminosity surface density for z {approx}> 2 galaxies relative to those at lower redshift. Typical galaxies at 1.5 {<=} z < 2.6 have a median dust obscuration L{sub IR}/L{sub UV} = 7.1 {+-} 1.1, which corresponds to a dust correction factor, required to recover the bolometric star formation rate (SFR) from the unobscured UV SFR, of 5.2 {+-} 0.6. This result is similar to that inferred from previous investigations of the UV, H{alpha}, 24 {mu}m, radio, and X-ray properties of the same galaxies studied here. Stacking in bins of UV slope ({beta}) implies that L* galaxies with redder spectral slopes are also dustier and that the correlation between {beta} and dustiness is similar to that found for local starburst galaxies. Hence, the rest-frame {approx_equal} 30 and

  19. GROUND-BASED Paα NARROW-BAND IMAGING OF LOCAL LUMINOUS INFRARED GALAXIES. I. STAR FORMATION RATES AND SURFACE DENSITIES

    Energy Technology Data Exchange (ETDEWEB)

    Tateuchi, Ken; Konishi, Masahiro; Motohara, Kentaro; Takahashi, Hidenori; Kato, Natsuko Mitani; Kitagawa, Yutaro; Todo, Soya; Toshikawa, Koji; Sako, Shigeyuki; Uchimoto, Yuka K.; Ohsawa, Ryou; Asano, Kentaro; Kamizuka, Takafumi; Nakamura, Tomohiko; Okada, Kazushi [Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Ita, Yoshifusa [Astronomical Institute, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Komugi, Shinya [Division of Liberal Arts, Kogakuin University, 2665-1, Hachioji, Tokyo 192-0015 (Japan); Koshida, Shintaro [Subaru Telescope, National Astronomical Observatory of Japan, Hilo, HI 96720 (United States); Manabe, Sho [Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan); Nakashima, Asami, E-mail: tateuchi@ioa.s.u-tokyo.ac.jp [Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); and others

    2015-03-15

    Luminous infrared galaxies (LIRGs) are enshrouded by a large amount of dust produced by their active star formation, and it is difficult to measure their activity in optical wavelengths. We have carried out Paα narrow-band imaging observations of 38 nearby star forming galaxies including 33 LIRGs listed in the IRAS Revised Bright Galaxy Sample catalog with the Atacama Near InfraRed camera on the University of Tokyo Atacama Observatory (TAO) 1.0 m telescope (miniTAO). Star formation rates (SFRs) estimated from the Paα fluxes, corrected for dust extinction using the Balmer decrement method (typically A{sub V} ∼ 4.3 mag), show a good correlation with those from the bolometric infrared luminosity of the IRAS data within a scatter of 0.27 dex. This suggests that the correction of dust extinction for the Paα flux is sufficient in our sample. We measure the physical sizes and surface densities of infrared luminosities (Σ{sub L(IR)}) and the SFR (Σ{sub SFR}) of star forming regions for individual galaxies, and we find that most of the galaxies follow a sequence of local ultra-luminous or luminous infrared galaxies (U/LIRGs) on the L(IR)-Σ{sub L(IR)} and SFR-Σ{sub SFR} plane. We confirm that a transition of the sequence from normal galaxies to U/LIRGs is seen at L(IR) = 8 × 10{sup 10} L {sub ☉}. Also, we find that there is a large scatter in physical size, different from normal galaxies or ULIRGs. Considering the fact that most U/LIRGs are merging or interacting galaxies, this scatter may be caused by strong external factors or differences in their merging stages.

  20. Probing the Circumgalactic Gas around High Redshift Galaxies with VUDS

    Science.gov (United States)

    Méndez-Hernández, Hugo; Cassata, Paolo; Ibar, Eduardo

    2017-07-01

    We probe the CGM of high redshift galaxies belonging to VIMOS Ultra Deep Survey. We used deep spectroscopy of different lines-of-sight around foreground galaxies to get useful information on the overall kinematics, chemical abundances, and (in some cases) estimates of the mass flux of cool material entrained in an in-outflow.We have selected a sample of 1244 close (0 150 kpc) galaxy pairs from the Vimos Ultra-Deep Survey (VUDS) to probe the circumgalactic medium (CGM) around galaxies at 2CIV, OISiII, CIV, AlII) out to galactocentric radii of ˜150 kpc on stacked spectra, and found that the CGM of galaxies at 2< z <5 are rich in metals even at ˜150 kpc away from the galaxies.

  1. Probing the Most Luminous Galaxies in the Universe at the Peak of Galaxy Assembly

    Science.gov (United States)

    Kartaltepe, Jeyhan

    2014-10-01

    What drives the most luminous galaxies in the universe at z~2, the peak of galaxy assembly? Is it the major merger of two gas rich disk systems as is the case in the local universe or can these extreme luminosities be driven by secular processes, such as the steady accretion of cold gas along filaments thought to play an important role in the early universe? Recent studies on the structure of high redshift luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs, respectively) have stirred up this controversy but have found a range of results leading to a confused picture of star formation in the early universe. In order to solve this question, we will search for unambiguous merger signatures (i.e., pairs, double nuclei, and tidal features) among a large sample of the more rare, extremely luminous HyLIRGs (L_IR > 10^13 L_sun) and the highest luminosity ULIRGs with a wide range of properties and separate them from galaxies that are clearly not mergers (e.g., structured disks). For those objects that remain ambiguous, particularly irregular clumpy systems, we will obtain ground-based IFU follow up observations to add detailed velocity information to the observed morphologies. The large volume probed by the COSMOS field at these high redshifts is an excellent complement to the smaller area fields covered by the CANDELS survey. While CANDELS imaging is excellent for studying the properties of less luminous but more common LIRGs and ULIRGs, it completely misses the more rare, extreme sources. Combined, these data will allow the detailed study of IR galaxies across a range of luminosities spanning over two orders of magnitude.

  2. Close companions to two high-redshift quasars

    Energy Technology Data Exchange (ETDEWEB)

    McGreer, Ian D.; Fan, Xiaohui; Bian, Fuyan [Steward Observatory, The University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Strauss, Michael A. [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544 (United States); Haiman, Zoltàn [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Jiang, Linhua [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Schneider, Donald P., E-mail: imcgreer@as.arizona.edu [Department of Astronomy and Astrophysics and the Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802 (United States)

    2014-10-01

    We report the serendipitous discoveries of companion galaxies to two high-redshift quasars. SDSS J025617.7+001904 is a z = 4.79 quasar included in our recent survey of faint quasars in the SDSS Stripe 82 region. The initial MMT slit spectroscopy shows excess Lyα emission extending well beyond the quasar's light profile. Further imaging and spectroscopy with LBT/MODS1 confirms the presence of a bright galaxy (i {sub AB} = 23.6) located 2'' (12 kpc projected) from the quasar with strong Lyα emission (EW{sub 0} ≈ 100 Å) at the redshift of the quasar, as well as faint continuum. The second quasar, CFHQS J005006.6+344522 (z = 6.25), is included in our recent HST SNAP survey of z ∼ 6 quasars searching for evidence of gravitational lensing. Deep imaging with ACS and WFC3 confirms an optical dropout ∼4.5 mag fainter than the quasar (Y {sub AB} = 25) at a separation of 0.''9. The red i {sub 775} – Y {sub 105} color of the galaxy and its proximity to the quasar (5 kpc projected if at the quasar redshift) strongly favor an association with the quasar. Although it is much fainter than the quasar, it is remarkably bright when compared to field galaxies at this redshift, while showing no evidence for lensing. Both systems may represent late-stage mergers of two massive galaxies, with the observed light for one dominated by powerful ongoing star formation and for the other by rapid black hole growth. Observations of close companions are rare; if major mergers are primarily responsible for high-redshift quasar fueling then the phase when progenitor galaxies can be observed as bright companions is relatively short.

  3. Massive Clumps in Local Galaxies: Comparisons with High-redshift Clumps

    Science.gov (United States)

    Elmegreen, Bruce G.; Elmegreen, Debra Meloy; Sánchez Almeida, J.; Muñoz-Tuñón, C.; Dewberry, J.; Putko, J.; Teich, Y.; Popinchalk, M.

    2013-09-01

    Local UV-bright galaxies in the Kiso survey include clumpy systems with kiloparsec-size star complexes that resemble clumpy young galaxies in surveys at high redshift. We compare clump masses and underlying disks in several dozen galaxies from each of these surveys to the star complexes and disks of normal spirals. Photometry and spectroscopy for the Kiso and spiral sample come from the Sloan Digital Sky Survey. We find that the largest Kiso clumpy galaxies resemble Ultra Deep Field (UDF) clumpies in terms of the star formation rates, clump masses, and clump surface densities. Clump masses and surface densities in normal spirals are smaller. If the clump masses are proportional to the turbulent Jeans mass in the interstellar medium, then for the most luminous galaxies in the sequence of normal:Kiso:UDF, the turbulent speeds and surface densities increase in the proportions 1.0:4.7:5.0 and 1.0:4.0:5.1, respectively, for fixed restframe B-band absolute magnitude. For the least luminous galaxies in the overlapping magnitude range, the turbulent speed and surface density trends are 1.0:2.7:7.4 and 1.0:1.4:3.0, respectively. We also find that while all three types have radially decreasing disk intensities when measured with ellipse-fit azimuthal averages, the average profiles are more irregular for UDF clumpies (which are viewed in their restframe UV) than for Kiso galaxies (viewed at g-band), and major axis intensity scans are even more irregular for the UDF than Kiso galaxies. Local clumpy galaxies in the Kiso survey appear to be intermediate between UDF clumpies and normal spirals.

  4. MASSIVE CLUMPS IN LOCAL GALAXIES: COMPARISONS WITH HIGH-REDSHIFT CLUMPS

    Energy Technology Data Exchange (ETDEWEB)

    Elmegreen, Bruce G. [IBM Research Division, T. J. Watson Research Center, Yorktown Hts., NY 10598 (United States); Elmegreen, Debra Meloy; Dewberry, J.; Putko, J.; Teich, Y.; Popinchalk, M. [Vassar College, Dept. of Physics and Astronomy, Poughkeepsie, NY 12604 (United States); Sanchez Almeida, J.; Munoz-Tunon, C. [Instituto de Astrof' sica de Canarias, C/via Lactea, s/n, E-38205, La Laguna, Tenerife (Spain)

    2013-09-01

    Local UV-bright galaxies in the Kiso survey include clumpy systems with kiloparsec-size star complexes that resemble clumpy young galaxies in surveys at high redshift. We compare clump masses and underlying disks in several dozen galaxies from each of these surveys to the star complexes and disks of normal spirals. Photometry and spectroscopy for the Kiso and spiral sample come from the Sloan Digital Sky Survey. We find that the largest Kiso clumpy galaxies resemble Ultra Deep Field (UDF) clumpies in terms of the star formation rates, clump masses, and clump surface densities. Clump masses and surface densities in normal spirals are smaller. If the clump masses are proportional to the turbulent Jeans mass in the interstellar medium, then for the most luminous galaxies in the sequence of normal:Kiso:UDF, the turbulent speeds and surface densities increase in the proportions 1.0:4.7:5.0 and 1.0:4.0:5.1, respectively, for fixed restframe B-band absolute magnitude. For the least luminous galaxies in the overlapping magnitude range, the turbulent speed and surface density trends are 1.0:2.7:7.4 and 1.0:1.4:3.0, respectively. We also find that while all three types have radially decreasing disk intensities when measured with ellipse-fit azimuthal averages, the average profiles are more irregular for UDF clumpies (which are viewed in their restframe UV) than for Kiso galaxies (viewed at g-band), and major axis intensity scans are even more irregular for the UDF than Kiso galaxies. Local clumpy galaxies in the Kiso survey appear to be intermediate between UDF clumpies and normal spirals.

  5. Precessing Jet in the High-Redshift Blazar J0017+8135

    Directory of Open Access Journals (Sweden)

    Kristóf Rozgonyi

    2016-08-01

    Full Text Available The prominent flat-spectrum radio quasar J0017+8135 (S5 0014+81 at z = 3.366 is one of the most luminous active galactic nuclei (AGN known. Its milliarcsecond-scale radio jet structure has been studied with very long baseline interferometry (VLBI since the 1980s. The quasar was selected as one of the original defining objects of the International Celestial Reference Frame, but left out from its current second realization (ICRF2 because of systematic long-term positional variations. Here we analyse archival 8.6- and 2.3-GHz VLBI imaging data collected at nearly 100 different epochs during more than 20 years, to obtain information about the kinematics of jet components. Because of the cosmological time dilation, extensive VLBI monitoring data are essential to reveal changes in the jet structure of high-redshift AGN. In the case of J0017+8135, the data can be described with a simple kinematic model of jet precession with a 12-year periodicity in the observer’s frame.

  6. The luminous infrared composite Seyfert 2 galaxy NGC 7679 through the [O III] λ 5007 emission line

    Science.gov (United States)

    Yankulova, I. M.; Golev, V. K.; Jockers, K.

    2007-07-01

    Context: NGC 7679 (Mrk 534) is a nearby (z = 0.0177) nearly face-on SB0 luminous infrared Sy2 galaxy in which starburst and AGN activities co-exist. The ionization structure is maintained by both the AGN power-law continuum and starburst. The galaxy is a bright X-ray source possessing a low X-ray column density NH Ukraine National Astronomical Observatory at peak Terskol, Caucasus, Russia. The observations were carried out in October 1996 with the Focal Reducer of the Max-Planck-Institut für Sonnensystemforschung, Germany. All observations were taken with tunable Fabry-Perot narrow-band imaging with spectral FWHM of the Airy profile δλ between 3 and 4 Å depending on the used wavelength. Results: The [O III]λ5007 emission-line image of the circumnuclear region of NGC 7679 shows elliptical isophotes extended along the PA ≈ 80° in the direction of the counterpart galaxy NGC 7682. There is a maximum of this emission which is shifted ~4 arcsec from the center as defined by the continuum emission. The maximum of ionization by the AGN power-law continuum traced by [O III]λ5007/Hα ratio is displaced by ~13 arcsec eastward from the nucleus. The direction where high ionization is observed at PA ≈ 80° ± 10° coincides with the direction to the companion galaxy NGC 7682 (PA ≈ 72°). On the contrary, at PA ~ 0° the ionization in the circumnuclear region is entirely due to hot stars. Conclusions: Both the ratio (N_ph/N_ion)hν > 55 eV ≈ 0.2-20 of the number N_ph of photons traced by [O III] to the number N_ion of high-energy ionizing photons and the presence of weak and elusive Hα broad wings indicate a hidden AGN. We conclude that the dust and gas in the high ionization direction PA ≈ 80° has a direct view to the central AGN engine. This possibly results in dust/star-formation decay. A large fraction of the unabsorbed Compton-thin Sy2s with [O III] luminosity ⪆1041 erg s-1 possesses a hidden AGN source. Based on observations obtained at the Peak Terskol

  7. Opening the low frequency window to the high redshift Universe

    NARCIS (Netherlands)

    Vedantham, Harish

    2015-01-01

    The epoch of formation of the first luminous structures (stars and galaxies) called the Comic Dawn, is one of the last unexplored periods in the history of the Universe. A new generation of radio telescopes such as LOFAR aim to revolutionize our understanding of structure formation in the early

  8. X-RAY ABSORPTION OF HIGH-REDSHIFT QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Eitan, Assaf; Behar, Ehud, E-mail: sassafe@tx.technion.ac.il, E-mail: behar@physics.technion.ac.il [Physics Department, Technion, Haifa 32000 (Israel)

    2013-09-01

    The soft X-ray photoelectric absorption of high-z quasars has been known for two decades, but has no unambiguous astrophysical context. We construct the largest sample to date of 58 high-redshift quasars (z > 0.45) selected from the XMM-Newton archive based on a high photon count criterion (>1800). We measure the optical depth {tau} at 0.5 keV and find that 43% of the quasars show significant absorption. We aim to find which physical parameters of the quasars, e.g., redshift, radio luminosity, radio loudness, or X-ray luminosity, drive their observed absorption. We compare the absorption behavior with redshift with the pattern expected if the diffuse intergalactic medium (IGM) is responsible for the observed absorption. We also compare the absorption with a comparison sample of gamma-ray burst (GRB) X-ray afterglows. Although the z > 2 quasar opacity is consistent with diffuse IGM absorption, many intermediate-z (0.45 < z < 2) quasars are not sufficiently absorbed for this scenario, and are appreciably less absorbed than GRBs. Only 10/37 quasars at z < 2 are absorbed, and only 5/30 radio-quiet quasars are absorbed. We find a weak correlation between {tau} and z, and an even weaker correlation between {tau} and radio luminosity. These findings lead to the conclusion that although a diffuse IGM origin for the quasar absorption is unlikely, the optical depth does seem to increase with redshift, roughly as (1 + z){sup 2.2{+-}0.6}, tending to {tau} Almost-Equal-To 0.4 at high redshifts, similar to the high-z GRBs. This result can be explained by an ionized and clumpy IGM at z < 2, and a cold, diffuse IGM at higher redshift. If, conversely, the absorption occurs at the quasar, and owing to the steep L{sub x} {proportional_to}(1 + z){sup 7.1{+-}0.5} correlation in the present sample, the host column density scales as N{sub H}{proportional_to}L{sub x}{sup 0.7{+-}0.1}.

  9. Tracing a high redshift cosmic web with quasar systems

    Science.gov (United States)

    Einasto, Maret; Tago, Erik; Lietzen, Heidi; Park, Changbom; Heinämäki, Pekka; Saar, Enn; Song, Hyunmi; Liivamägi, Lauri Juhan; Einasto, Jaan

    2014-08-01

    Context. To understand the formation, evolution, and present-day properties of the cosmic web we need to study it at low and high redshifts. Aims: We trace the cosmic web at redshifts that range from 1.0 ≤ z ≤ 1.8 by using the quasar (QSO) data from the SDSS DR7 QSO catalogue. Methods: We apply a friend-of-friend algorithm to the quasar and random catalogues to determine systems at a series of linking length and analyse richness and sizes of these systems. Results: At the linking lengths l ≤ 30 h-1 Mpc, the number of quasar systems is larger than the number of systems detected in random catalogues, and the systems themselves have smaller diameters than random systems. The diameters of quasar systems are comparable to the sizes of poor galaxy superclusters in the local Universe. The richest quasar systems have four members. The mean space density of quasar systems, ≈ 10-7 (h-1 Mpc)-3, is close to the mean space density of local rich superclusters. At intermediate linking lengths (40 ≤ l ≤ 70 h-1 Mpc), the richness and length of quasar systems are similar to those derived from random catalogues. Quasar system diameters are similar to the sizes of rich superclusters and supercluster chains in the local Universe. The percolating system, which penetrate the whole sample volume appears in a quasar sample at a smaller linking length than in random samples (85 h-1 Mpc). At the linking length 70 h-1 Mpc, the richest systems of quasars have diameters exceeding 500 h-1 Mpc. Quasar luminosities in systems are not correlated with the system richness. Conclusions: Quasar system catalogues in our web pages and at the Strasbourg Astronomical Data Center (CDS) serve as a database for searching superclusters of galaxies and for tracing the cosmic web at high redshifts. Appendix A is available in electronic form at http://www.aanda.orgThe catalogues are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  10. The formation and evolution of high-redshift dusty galaxies

    Science.gov (United States)

    Ma, Jingzhe; Gonzalez, Anthony H.; Ge, Jian; Vieira, Joaquin D.; Prochaska, Jason X.; Spilker, Justin; Strandet, Maria; Ashby, Matthew; Noterdaeme, Pasquier; Lundgren, Britt; Zhao, Yinan; Ji, Tuo; Zhang, Shaohua; Caucal, Paul; SPT SMG Collaboration

    2017-01-01

    Star formation and chemical evolution are among the biggest questions in galaxy formation and evolution. High-redshift dusty galaxies are the best sites to investigate mass assembly and growth, star formation rates, star formation history, chemical enrichment, and physical conditions. My thesis is based on two populations of high-redshift dusty galaxies, submillimeter galaxies (SMGs) and quasar 2175 Å dust absorbers, which are selected by dust emission and dust absorption, respectively.For the SMG sample, I have worked on the gravitationally lensed dusty, star-forming galaxies (DSFGs) at 2.8 thesis is focused on the stellar masses and star formation rates of these objects by means of multi-wavelength spectral energy distribution (SED) modelling. The data include HST/WFC3, Spitzer/IRAC, Herschel/PACS, Herschel/SPIRE, APEX/Laboca and SPT. Compared to the star-forming main sequence (MS), these DSFGs have specific SFRs that lie above the MS, suggesting that we are witnessing ongoing strong starburst events that may be driven by major mergers. SPT0346-52 at z = 5.7, the most extraordinary source in the SPT survey for which we obtained Chandra X-ray and ATCA radio data, was confirmed to have the highest star formation surface density of any known galaxy at high-z.The other half of my thesis is focused on a new population of quasar absorption line systems, 2175 Å dust absorbers, which are excellent probes of gas and dust properties, chemical evolution and physical conditions in the absorbing galaxies. This sample was selected from the SDSS and BOSS surveys and followed up with the Echelle Spectrographs and Imager on the Keck-II telescope, the Red & Blue Channel Spectrograph on the Multiple Mirror Telescope, and the Ultraviolet and Visible Echelle Spectrograph onboard the Very Large Telescope. We found a correlation between the presence of the 2175 Å bump and other ingredients including high metallicity, high depletion level, overall low ionization state of gas, neutral

  11. Planck 2013 results. XVIII. Gravitational lensing-infrared background correlation

    CERN Document Server

    Ade, P.A.R.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Bartlett, J.G.; Basak, S.; Battaner, E.; Benabed, K.; Benoit, A.; Benoit-Levy, A.; Bernard, J.P.; Bersanelli, M.; Bethermin, M.; Bielewicz, P.; Bobin, J.; Bock, J.J.; Bonaldi, A.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Boulanger, F.; Bridges, M.; Bucher, M.; Burigana, C.; Butler, R.C.; Cardoso, J.F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, L.Y.; Chiang, H.C.; Christensen, P.R.; Church, S.; Clements, D.L.; Colombi, S.; Colombo, L.P.L.; Couchot, F.; Coulais, A.; Crill, B.P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.M.; Desert, F.X.; Diego, J.M.; Dole, H.; Donzelli, S.; Dore, O.; Douspis, M.; Dupac, X.; Efstathiou, G.; Ensslin, T.A.; Eriksen, H.K.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giardino, G.; Giraud-Heraud, Y.; Gonzalez-Nuevo, J.; Gorski, K.M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J.E.; Hansen, F.K.; Hanson, D.; Harrison, D.; Henrot-Versille, S.; Hernandez-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Jaffe, T.R.; Jaffe, A.H.; Jones, W.C.; Juvela, M.; Keihanen, E.; Keskitalo, R.; Kisner, T.S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lacasa, F.; Lagache, G.; Lahteenmaki, A.; Lamarre, J.M.; Lasenby, A.; Laureijs, R.J.; Lawrence, C.R.; Leonardi, R.; Leon-Tavares, J.; Lesgourgues, J.; Liguori, M.; Lilje, P.B.; Linden-Vornle, M.; Lopez-Caniego, M.; Lubin, P.M.; Macias-Perez, J.F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D.J.; Martin, P.G.; Martinez-Gonzalez, E.; Masi, S.; Matarrese, S.; Matthai, F.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschenes, M.A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C.B.; Norgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Oxborrow, C.A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G.W.; Prezeau, G.; Prunet, S.; Puget, J.L.; Rachen, J.P.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Seiffert, M.D.; Serra, P.; Shellard, E.P.S.; Spencer, L.D.; Starck, J.L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.S.; Sygnet, J.F.; Tauber, J.A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L.A.; Wandelt, B.D.; White, S.D.M.; Yvon, D.; Zacchei, A.; Zonca, A.

    2014-01-01

    The multi-frequency capability of the Planck satellite provides information both on the integrated history of star formation (via the cosmic infrared background, or CIB) and on the distribution of dark matter (via the lensing effect on the cosmic microwave background, or CMB). The conjunction of these two unique probes allows us to measure directly the connection between dark and luminous matter in the high redshift (1 1. We measure directly the SFR density with around 2 sigma significance for three redshift bins between z=1 and 7, thus opening a new window into the study of the formation of stars at early times.

  12. Constraints from high redshift supernovae upon scalar field cosmologies

    Energy Technology Data Exchange (ETDEWEB)

    Frieman, J.A. [NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, Illinois60510 (United States)]|[Department of Astronomy and Astrophysics, University of Chicago, Chicago, Illinois60637 (United States); Waga, I. [Universidade Federal do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro, RJ, 21945-970 (Brazil)

    1998-04-01

    Recent observations of high-redshift type Ia supernovae have placed stringent constraints on the cosmological constant {Lambda}. We explore the implications of these SNe observations for cosmological models in which a classically evolving scalar field currently dominates the energy density of the Universe. Such models have been shown to share the advantages of {Lambda} models: compatibility with the spatial flatness predicted by inflation; a Universe older than the standard Einstein{endash}de Sitter model; and, combined with cold dark matter, predictions for large-scale structure formation in good agreement with data from galaxy surveys. Compared to the cosmological constant, these scalar field models are consistent with the SNe observations for a lower matter density, {Omega}{sub m0}{approximately}0.2, and a higher age, H{sub 0}t{sub 0}{approx_gt}1. Combined with the fact that scalar field models imprint a distinctive signature on the cosmic microwave background anisotropy, they remain currently viable and should be testable in the near future. {copyright} {ital 1998} {ital The American Physical Society}

  13. Angular Momentum Evolution Of Disk Galaxies At High Redshift

    Science.gov (United States)

    Okamura, Taku; Kazuhiro, Shimasaku; Ryota, Kawamata

    2017-06-01

    The stellar disk size of a galaxy depends on the fraction of the dark-halo mass settled as disk stars, m★= M★/Mdh, and the fraction of the dark-halo angular momentum transferred to the disk, j★ = J★/Jdh. Since j★ is also determined by various star-formation related mechanisms such as inflows and feedbacks, measuring j★ and m★ at high redshifts is needed to understand the formation history of disk galaxies. We use the 3D-HST GOODS-S, COSMOS, and AEGIS imaging data and photo-z catalogs to examine j★ and m★ for star-forming galaxies at z 2,3,4, when disks are actively forming. We find that the j★/m★ ratio is roughly constant at ≃ 0.8 for all three redshifts over the entire halo mass range examined. This high ratio is close to those of local disk galaxies but a factor of a few higher than predicted (at z 2) by galaxy formation models. We also find that a significant fraction of our galaxies appear to be unstable against bar formation.

  14. Magnetically Regulated Gas Accretion in High-Redshift Galactic Disks

    Science.gov (United States)

    Birnboim, Yuval

    2009-09-01

    Disk galaxies are in hydrostatic equilibrium along their vertical axis. The pressure allowing for this configuration consists of thermal, turbulent, magnetic, and cosmic-ray components. For the Milky Way the thermal pressure contributes ~10% of the total pressure near the plane, with this fraction dropping toward higher altitudes. Out of the rest, magnetic fields contribute ~1/3 of the pressure to distances of ~3 kpc above the disk plane. In this Letter, we attempt to extrapolate these local values to high-redshift, rapidly accreting, rapidly star-forming disk galaxies and study the effect of the extra pressure sources on the accretion of gas onto the galaxies. In particular, magnetic field tension may convert a smooth cold-flow accretion to clumpy, irregular star formation regions and rates. The infalling gas accumulates on the edge of the magnetic fields, supported by magnetic tension. When the mass of the infalling gas exceeds some threshold mass, its gravitational force cannot be balanced by magnetic tension anymore, and it falls toward the disk's plane, rapidly making stars. Simplified estimations of this threshold mass are consistent with clumpy star formation observed in SINS, UDF, GOODS, and GEMS surveys. We discuss the shortcomings of pure hydrodynamic codes in simulating the accretion of cold flows into galaxies, and emphasize the need for magnetohydrodynamic simulations.

  15. Investigating the Local and High Redshift Universe With Deep Survey Data and Ground-Based Spectroscopy

    Science.gov (United States)

    Masters, Daniel Charles

    Large multiwavelength surveys are now driving the frontiers of astronomical research. I describe results from my work using data from two large astronomical surveys: the Cosmic Evolution Survey (COSMOS), which has obtained deep photometric and spectroscopic data on two square degrees of the sky using many of the most powerful telescopes in the world, and the WFC3 Infrared Spectroscopic Parallels (WISP) Survey, which uses the highly sensitive slitless spectroscopic capability of the Hubble Space Telescope Wide Field Camera 3 to detect star-forming galaxies over most of the universe's history. First I describe my work on the evolution of the high-redshift quasar luminosity function, an important observational quantity constraining the growth of the supermassive black holes in the early universe. I show that the number density of faint quasars declines rapidly above z ˜ 3. This result is discussed in the context of cosmic reionization and the coevolution of galaxies and their central black holes. Next I present results of a multi-year campaign of near-infrared spectroscopy with FIRE, a world-class near-infrared spectrometer on the Magellan Baade 6.5 meter telescope in Chile, targeting emission-line galaxies at z ˜ 2 discovered with the Hubble Space Telescope. Our results showed that the typical emission-line galaxy at this redshift has low-metallicity, low dust obscuration, high ionization parameter, and little evidence for significant active galactic nucleus (AGN) contribution to the emission lines. We also find evidence that high redshift star-forming galaxies have enhanced nitrogen abundances. This result has interesting implications for the nature of the star formation in such galaxies -- in particular, it could mean that a large fraction of such galaxies harbor substantial populations of Wolf-Rayet stars, which are massive, evolved stars ejecting large amounts of enriched matter into the interstellar medium. Finally, I will discuss the discovery of three

  16. Using CO as a Physical Probe of the SF Activity in the Planck-Herschel Selected Hyper Luminous Infrared Galaxies

    Science.gov (United States)

    Harrington, Kevin

    2018-01-01

    Multi-J CO line studies are essential for quantifying the physical properties of the star-forming ISM, yet it is observationally expensive to detect those faint CO emission lines at high redshift. Our eight Planck-Herschel selected galaxies, with apparent LIR > 1013‑14 L⊙, serve as the best laboratories to conduct such a CO spectral line energy distribution analysis at high-z. Using our GBT and LMT (Jup = 1-3) measurements, we trace the bulk molecular gas mass, finding relatively large star formation efficiencies (as traced by the LIR-to-L’CO(1‑0) ratio) consistent with a starburst mode of activity. With our mid-J (Jup = 4-8) CO line measurements, obtained with the IRAM 30m telescope, we find gas excitation conditions ranging from sub-thermal SMGs to highly excited local starbursts out to Jup = 5-8. The consistently high velocity-integrated line intensities at Jup = 5-8 indicates the presence a warm/dense component responsible for exciting the higher-J CO lines, therefore we use coupled non-LTE large velocity gradient and dust radiative transfer models to begin characterising the two-component molecular ISM in these strongly lensed systems.

  17. Large fluctuations in the high-redshift metagalactic ionizing background

    Science.gov (United States)

    D'Aloisio, Anson; McQuinn, Matthew; Davies, Frederick B.; Furlanetto, Steven R.

    2018-01-01

    Recent observations have shown that the scatter in opacities amongst coeval segments of the Ly α forest increases rapidly at z > 5. In this paper, we assess whether the large scatter can be explained by fluctuations in the ionizing background in the post-reionization intergalactic medium. We find that matching the observed scatter at z ≈ 5.5 requires a short spatially averaged mean free path of 〈λmfp912〉 ≲ 15 h- 1 comoving Mpc, a factor of ≳3 shorter than direct measurements at z = 5.2. We argue that such rapid evolution in the mean free path is difficult to reconcile with our measurements of the global H I photoionization rate, which stay approximately constant over the interval z ≈ 4.8-5.5. However, we also show that measurements of the mean free path at z > 5 are likely biased towards higher values by the quasar proximity effect. This bias can reconcile the short values of 〈λmfp912〉 that are required to explain the large scatter in opacities. We discuss the implications of this scenario for cosmological reionization. Finally, we investigate whether other statistics applied to the z > 5 Ly α forest can shed light on the origin of the scatter. Compared to a model with a uniform ionizing background, models that successfully account for the scatter lead to enhanced power in the line-of-sight flux power spectrum on scales k ≲0.1 h Mpc-1. We find tentative evidence for this enhancement in observations of the high-redshift Ly α forest.

  18. Identifying gamma-ray bursts at very high redshifts

    Science.gov (United States)

    Tanvir, Nial

    2017-08-01

    Gamma-ray bursts are bright enough to be seen to very great distances and their afterglows can provide redshifts and positions for their host galaxies, and in some cases details of the ISM and the IGM close to the burst, irrespective of the host magnitude itself. Thus GRBs, despite their small numbers, offer a unique and powerful tracer of early star formation and the galaxy populations in the era of reionization. Our efforts to identify high-z GRBs have been rewarded with the discoveries of GRB 090423 and GRB 120923A at spectroscopic redshifts of 8.2 and 7.8 respectively. However, it remains the case that some good candidate high-z GRBs cannot be followed up quickly or deeply enough with ground-based IR spectroscopy, and indeed for others the Ly-alpha break may fall in regions of the IR spectrum difficult to access from the ground. GRB 090429B is an example, which had a photo-z of 9.4, but for which spectroscopy was curtailed due to bad weather. WFC3/IR on HST can obtain redshifts based on the location of the Ly-alpha break via slitless grism spectroscopy to considerably deeper limits (and hence later times) than is possible from the ground, thus offering a solution to this problem. This proposal aims to continue to build the sample of z>7 GRBs by obtaining spectroscopy for up to two candidates for which photometry suggests a very high redshift, but where the redshift could not be secured from the ground. This will provide an important legacy of host galaxy targets with known redshifts for future studies with JWST. The low rate of z>7 GRBs leads us to request a long-term ToO program, spanning cycles 25 and 26.

  19. Probing the Intergalactic Medium with high-redshift quasars

    Science.gov (United States)

    Calverley, Alexander Peter

    2011-11-01

    Clues about the timing of reionization and the nature of the ionizing sources responsible are imprinted in the ionization and thermal state of the IGM. In this thesis, I use high-resolution quasar spectra in conjunction with state-of-the-art hydrodynamical simulations to probe the IGM at high redshift, focusing on the ionization and thermal state of the gas. After reionization, the ionization state of the IGM is set by the intensity of the ultraviolet background (UVB), quantified by the hydrogen photoionization rate, Γ_bkg. At high redshifts this has been estimated by measuring the mean flux in the Lyα forest, and scaling Γ_bkg in simulations such that the simulated mean flux matches the observed value. In Chapter 3 I investigate whether the precision of these estimates can be improved by using the entire flux probability distribution function (PDF) instead of only the mean flux. Although I find it cannot improve the precision directly, the flux PDF can potentially be used to constrain other sources of error in observational estimates of Γ_bkg, and so may increase the precision indirectly. The ionizing output of a quasar will locally dominate over the UVB, and this leads to enhanced transmission bluewards of the quasar Lyα line, known as the proximity effect. In Chapter 4 I present the first measurements of Γ_bkg at z > 5 from the proximity effect. The UVB intensity declines smoothly with redshift over 4.6 6.4. There is a drop in Γ_bkg by roughly a factor of five, which corresponds to a drop in the ionizing emissivity by about a factor of two. Such a redshift evolution in the emissivity cannot continue to much higher redshift without reionization failing to complete, which suggests that reionization cannot have ended much higher than z = 6.4. Estimates of Γ_bkg from the proximity effect and the mean flux are generally discrepant at z ∼ 2-4, with those from the proximity effect systematically higher. This is generally attributed to effects of the

  20. Host galaxies of high-redshift quasars with extreme outflows

    Science.gov (United States)

    Zakamska, Nadia

    2016-10-01

    Feedback from accreting supermassive black holes is now a standard ingredient in galaxy formation models. It has long been speculated that powerful quasars, triggered in major gas-rich mergers, had a profound impact on galaxy formation via quasar-driven winds. This process must have been at its peak during the epoch of most active galaxy formation and quasar activity at z=2-3, yet there is not yet any direct observational support for this long-hypothesized process. We have discovered a population of extremely luminous (L>1e47 erg/s) red quasars with peculiar line properties at z=2-3 which show unprecedented signatures of powerful v>2000 km/s outflows in their [OIII]5007A lines. We propose to image eleven of these objects with the HST in two filters, one probing rest-frame UV and one probing the rest-frame optical. The rest-frame optical observations will directly probe the dynamical state and extent of the hosts of luminous obscured quasars and search for companions and merger signatures. We will determine the masses of the stellar component to determine if the bulges of the quasar hosts have already become apparent in this epoch. Using the rest-frame UV observations, we will probe the distribution of the gas in quasar hosts by observing the morphology of ongoing star formation and scattered light from the central engine. Our targets are the best candidates to probe the long-speculated merger-driven scenario for quasar activity, and our proposed HST observations will definitively determine whether this process drives the evolution of massive galaxies.

  1. The Origin and Evolution of Interstellar Dust in the Local and High-redshift Universe

    Science.gov (United States)

    Dwek, Eliahu

    2012-01-01

    In this talk I will begin by reviewing our current state of knowledge regarding the origin and evolution of dust in the local solar neighborhood. using chemical evolution models, I will discuss their many different input parameters and their uncertainties. An important consequence of these models is the delayed injection of dust from AGB stars, compared to supernova-condensed dust, into the interstellar medium. I will show that these stellar evolutionary effects on dust composition are manifested in the infrared spectra of local galaxies. The delayed production of dust in AGB stars has also important consequences for the origin of the large amount of dust detected in high-redshift galaxies, when the universe was less that approx. 1 Gyr old. Supernovae may have been the only viable dust sources in those galaxies. Recent observations of sN1987a show a significant mass of dust in the ejecta of this SN. Is that production rate high enough to account for the observed dust mass in these galaxies? If not, what are the alternative viable sources of dust, and how do they depend on the nature of the galaxy (starburst or AGN) and its star formation history .

  2. Quantitative comparison between Type Ia supernova spectra at low and high redshifts: A case study

    Energy Technology Data Exchange (ETDEWEB)

    Supernova Cosmology Project; Nugent, Peter E; Garavini, G.; Folatelli, G.; Nobili, S.; Aldering, G.; Amanullah, R.; Antilogus, P.; Astier, P.; Blanc, G.; Bronder, J.; Burns, M.S.; Conley, A.; Deustua, S. E.; Doi, M.; Fabbro, S.; Fadeyev, V.; Gibbons, R.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hook, I.; Howell, D. A.; Kashikawa, N.; Kim, A. G.; Kowalski, M.; Kuznetsova, N.; Lee, B. C.; Lidman, C.; Mendez, J.; Morokuma, T.; Motohara, K.; Nugent, P. E.; Pain, R.; Perlmutter, S.; Quimby, R.; Raux, J.; Regnault, N.; Ruiz-Lapuente, P.; Sainton, G.; Schahmaneche, K.; Smith, E.; Spadafora, A. L.; Stanishev, V.; Thomas, R. C.; Walton, N. A.; Wang, L.; Wood-Vasey, W. M.; Yasuda, N.

    2008-03-24

    We develop a method to measure the strength of the absorption features in type Ia supernova (SN Ia) spectra and use it to make a quantitative comparisons between the spectra of type Ia supernovae at low and high redshifts. In this case study, we apply the method to 12 high-redshift (0.212 = z = 0.912) SNe Ia observed by the Supernova Cosmology Project. Through measurements of the strengths of these features and of the blueshift of theabsorption minimum in Ca ii H&K, we show that the spectra of the high-redshift SNe Ia are quantitatively similar to spectra of nearby SNe Ia (z< 0.15). One supernova in our high redshift sample, SN 2002fd at z = 0.279, is found to have spectral characteristics that are associated with peculiar SN 1991T/SN 1999aa-like supernovae.

  3. High-redshift gamma-ray bursts: observational signatures of superconducting cosmic strings?

    Science.gov (United States)

    Cheng, K S; Yu, Yun-Wei; Harko, T

    2010-06-18

    The high-redshift gamma-ray bursts (GRBs), GRBs 080913 and 090423, challenge the conventional GRB progenitor models by their short durations, typical for short GRBs, and their high energy releases, typical for long GRBs. Meanwhile, the GRB rate inferred from high-redshift GRBs also remarkably exceeds the prediction of the collapsar model, with an ordinary star formation history. We show that all these contradictions could be eliminated naturally, if we ascribe some high-redshift GRBs to electromagnetic bursts of superconducting cosmic strings. High-redshift GRBs could become a reasonable way to test the superconducting cosmic string model because the event rate of cosmic string bursts increases rapidly with increasing redshifts, whereas the collapsar rate decreases.

  4. Spitzer's View of Galaxies in the High-Redshift Universe

    Science.gov (United States)

    Fazio, Giovanni G.

    One of the most important observations made by the Spitzer Space Telescope has been the detection of luminous galaxies back to the era of reionization (z ~ 8), when the universe was less than 700 million years old. The key advance made by Spitzer imaging isthe ability, for the first time, to sample the redshifted rest-frame visible light of these galaxies. When combined with broadband multi-wavelength data, Spitzer observations can be fit to stellar population synthesis models to determine the spectral energy distribution of these galaxies and to constrain their stellar masses and ages and their star formation histories. As a result, there is evidence that most of the stellar mass of these galaxies formed at even higher redshifts (z > 10 to 12) and that asignificant number of galaxies should exist in this region.Searches for galaxies at z ~ 9 to 10 continue. Spitzer observations of massive lensing clusters have also played a pivotal role in this study. The first IRAC detection of a z >6 galaxy came from such observations. Since most of these results were obtained with Spitzer/IRAC 3.6/4.5 μm bands, the Spitzer Warm Mission, when combined with future HST/WFC3 observations, will provide a unique opportunity to obtain the first complete census of the assembly of stellar mass as a function of cosmic time back to the era of reionization, yielding unique information on galaxy formation in the early universe.

  5. Clustering of High Redshift (z>2.9) Quasars from the Sloan Digital Sky Survey

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yue; Strauss, Michael A.; Oguri, Masamune; Hennawi, Joseph F.; Fan, Xiaohui; Richards, Gordon T.; Hall, Patrick B.; Schneider, Donald P.; Szalay, Alexander S.; Thakar, Anirudda R.; Berk, Daniel E.Vanden; Anderson, Scott F.; Bahcall, Neta A.; /KIPAC, Menlo Park

    2006-11-30

    We study the two-point correlation function of a uniformly selected sample of 4,428 optically selected luminous quasars with redshift 2.9 {le} z {le} 5.4 selected over 4041 deg{sup 2} from the Fifth Data Release of the Sloan Digital Sky Survey. We fit a power-law to the projected correlation function w{sub p}(r{sub p}) to marginalize over redshift space distortions and redshift errors. For a real-space correlation function of the form {zeta}(r) = (r/r{sub 0}){sup -{gamma}}, the fitted parameters in comoving coordinates are r{sub 0} = 15.2 {+-} 2.7 h{sup -1} Mpc and {gamma} = 2.0 {+-} 0.3, over a scale range 4 {le} r{sub p} {le} 150 h{sup -1} Mpc. Thus high-redshift quasars are appreciably more strongly clustered than their z {approx} 1.5 counterparts, which have a comoving clustering length r{sub 0} {approx} 6.5 h{sup -1} Mpc. Dividing our sample into two redshift bins: 2.9 {le} z {le} 3.5 and z {ge} 3.5, and assuming a power-law index {gamma} = 2.0, we find a correlation length of r{sub 0} = 16.9 {+-} 1.7 h{sup -1} Mpc for the former, and r{sub 0} = 24.3 {+-} 2.4 h{sup -1} Mpc for the latter. Strong clustering at high redshift indicates that quasars are found in very massive, and therefore highly biased, halos. Following Martini & Weinberg, we relate the clustering strength and quasar number density to the quasar lifetimes and duty cycle. Using the Sheth & Tormen halo mass function, the quasar lifetime is estimated to lie in the range 4 {approx} 50 Myr for quasars with 2.9 {le} z {le} 3.5; and 30 {approx} 600 Myr for quasars with z {ge} 3.5. The corresponding duty cycles are 0.004 {approx} 0.05 for the lower redshift bin and 0.03 {approx} 0.6 for the higher redshift bin. The minimum mass of halos in which these quasars reside is 2-3 x 10{sup 12} h{sup -1} M{sub {circle_dot}} for quasars with 2.9 {le} z {le} 3.5 and 4-6 x 10{sup 12} h{sup -1} M{sub {circle_dot}} for quasars with z {ge} 3.5; the effective bias factor b{sub eff} increases with redshift, e.g., b

  6. LUMINOUS AND HIGH STELLAR MASS CANDIDATE GALAXIES AT z Almost-Equal-To 8 DISCOVERED IN THE COSMIC ASSEMBLY NEAR-INFRARED DEEP EXTRAGALACTIC LEGACY SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Yan Haojing [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); Finkelstein, Steven L. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Huang, Kuang-Han [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Ryan, Russell E.; Ferguson, Henry C.; Koekemoer, Anton M.; Grogin, Norman A. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Dickinson, Mark [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Newman, Jeffrey A. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Somerville, Rachel S. [Physics and Astronomy Department, Rutgers University, Piscataway, NJ 08854 (United States); Dave, Romeel [Astronomy Department, University of Arizona, Tucson, AZ 85721 (United States); Faber, S. M. [University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Papovich, Casey [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States); Guo Yicheng; Giavalisco, Mauro [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Lee, Kyoung-soo [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Reddy, Naveen; Siana, Brian D. [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Cooray, Asantha R. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Hathi, Nimish P. [Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States); and others

    2012-12-20

    One key goal of the Hubble Space Telescope Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey is to track galaxy evolution back to z Almost-Equal-To 8. Its two-tiered ''wide and deep'' strategy bridges significant gaps in existing near-infrared surveys. Here we report on z Almost-Equal-To 8 galaxy candidates selected as F105W-band dropouts in one of its deep fields, which covers 50.1 arcmin{sup 2} to 4 ks depth in each of three near-infrared bands in the Great Observatories Origins Deep Survey southern field. Two of our candidates have J < 26.2 mag, and are >1 mag brighter than any previously known F105W-dropouts. We derive constraints on the bright end of the rest-frame ultraviolet luminosity function of galaxies at z Almost-Equal-To 8, and show that the number density of such very bright objects is higher than expected from the previous Schechter luminosity function estimates at this redshift. Another two candidates are securely detected in Spitzer Infrared Array Camera images, which are the first such individual detections at z Almost-Equal-To 8. Their derived stellar masses are on the order of a few Multiplication-Sign 10{sup 9} M{sub Sun }, from which we obtain the first measurement of the high-mass end of the galaxy stellar mass function at z Almost-Equal-To 8. The high number density of very luminous and very massive galaxies at z Almost-Equal-To 8, if real, could imply a large stellar-to-halo mass ratio and an efficient conversion of baryons to stars at such an early time.

  7. The Extremely Luminous Quasar Survey (ELQS) in SDSS and the high-z bright-end Quasar Luminosity Function

    Science.gov (United States)

    Schindler, Jan-Torge; Fan, Xiaohui; McGreer, Ian

    2018-01-01

    Studies of the most luminous quasars at high redshift directly probe the evolution of the most massive black holes in the early Universe and their connection to massive galaxy formation. Unfortunately, extremely luminous quasars at high redshift are very rare objects. Only wide area surveys have a chance to constrain their population. The Sloan Digital Sky Survey (SDSS) nd the Baryon Oscillation Spectroscopic Survey (BOSS) have so far provided the most widely adopted measurements of the type I quasar luminosity function (QLF) at z>3. However, a careful re-examination of the SDSS quasar sample revealed that the SDSS quasar selection is in fact missing a significant fraction of $z~3$ quasars at the brightest end.We have identified the purely optical color selection of SDSS, where quasars at these redshifts are strongly contaminated by late-type dwarfs, and the spectroscopic incompleteness of the SDSS footprint as the main reasons. Therefore we have designed the Extremely Luminous Quasar Survey (ELQS), based on a novel near-infrared JKW2 color cut using WISE AllWISE and 2MASS all-sky photometry, to yield high completeness for very bright (i learning algorithms on SDSS and WISE photometry for quasar-star classification and photometric redshift estimation.The ELQS is spectroscopically following up ~230 new quasar candidates in an area of ~12000 deg2 in the SDSS footprint, to obtain a well-defined and complete quasar sample for an accurate measurement of the bright-end quasar luminosity function (QLF) at 2.8<= z<=5.0. So far the ELQS has identified 75 bright new quasars in this redshift range and observations of the fall sky will continue until the end of the year. At the AAS winter meeting we will present the full spectroscopic results of the survey, including a re-estimation and extension of the high-z QLF toward higher luminosities.

  8. Probing Pre-Galactic Metal Enrichment with High-Redshift Gamma-Ray Bursts

    Science.gov (United States)

    Wang, F. Y.; Bromm, Volker; Greif, Thomas H.; Stacy, Athena; Dai, Z. G.; Loeb, Abraham; Cheng, K. S.

    2012-01-01

    We explore high-redshift gamma-ray bursts (GRBs) as promising tools to probe pre-galactic metal enrichment. We utilize the bright afterglow of a Population III (Pop III) GRB exploding in a primordial dwarf galaxy as a luminous background source, and calculate the strength of metal absorption lines that are imprinted by the first heavy elements in the intergalactic medium (IGM). To derive the GRB absorption line diagnostics, we use an existing highly resolved simulation of the formation of a first galaxy which is characterized by the onset of atomic hydrogen cooling in a halo with virial temperature approximately greater than10(exp 4) K.We explore the unusual circumburst environment inside the systems that hosted Pop III stars, modeling the density evolution with the self-similar solution for a champagne flow. For minihalos close to the cooling threshold, the circumburst density is roughly proportional to (1 + z) with values of about a few cm(exp -3). In more massive halos, corresponding to the first galaxies, the density may be larger, n approximately greater than100 cm(exp -3). The resulting afterglow fluxes are weakly dependent on redshift at a fixed observed time, and may be detectable with the James Webb Space Telescope and Very Large Array in the near-IR and radio wavebands, respectively, out to redshift z approximately greater than 20. We predict that the maximum of the afterglow emission shifts from near-IR to millimeter bands with peak fluxes from mJy to Jy at different observed times. The metal absorption line signature is expected to be detectable in the near future. GRBs are ideal tools for probing the metal enrichment in the early IGM, due to their high luminosities and featureless power-law spectra. The metals in the first galaxies produced by the first supernova (SN) explosions are likely to reside in low-ionization stages (C II, O I, Si II and Fe II). We show that, if the afterglow can be observed sufficiently early, analysis of the metal lines may

  9. Ultraviolet spectropolarimetry of high-redshift quasars with the Hubble Space Telescope

    Science.gov (United States)

    Impey, C. D.; Malkan, Matthew A.; Webb, Wayne; Petry, C. E.

    1995-01-01

    Ultraviolet spectropolarimetry of three bright high-redshift low-polarization quasars (LPQs) was obtained with the Faint Object Spectrograph of the Hubble Space Telescope (HST). Two of the quasars, PG 1634+706 and PG 2302+029, had polarizations p approximately = 0.5%-1.0% throughout the ultraviolet, and showed no significant variation of polarization amplitude or position angle with wavelength. PG 2302+029 was also marginally (2.4 sigma) circularly polarized in the optical continuum. For the highest redshift quasar, PG 1222+228 (Ton 1530), the polarization was measured down to rest wavelengths below 800 A. Although the continuum of PG 1222+228 was weakened by Lyman limit absorption from an intergalactic gas cloud, the polarization increased sharply from 1% to about 4.5%, a change of 4 sigma significance. This abrupt rise in polarization does not appear attributable to any known instrumental artifact. These UV polarizations were only slightly less than those previously observed for these same objects in the optical. The polarization spectra were flat with a typical slope of the polarized flux pF(sub nu) proportional to nu(exp -0.8 +/- 0.5). Unlike the case of several high luminosity Seyfert 1 nuclei studied previously, polarization caused by scattering from dust grains does not provide the best fit to the polarization spectra of these luminous quasars. These observed spectra are consistent with a wavelength-independent polarization proportional to the total nonstellar light or, possibly, to the contribution of the blue thermal component. The polarization spectra have insufficient signal-to-noise to locate the scatterers with respect to the continuum source and the much larger broad line region. A decrease in amplitude and rotation of the position angle of the polarization vector at the shortest wavelengths, which could result from general relativistic effects near a spinning black hole, was not observed. In fact, in PG 1222+228, the polarization was observed to

  10. Physical conditions of the interstellar medium in high-redshift submillimetre bright galaxies

    Science.gov (United States)

    Yang, Chentao

    2017-12-01

    The discovery of a population of high- redshift dust-obscured submillimeter galaxies (SMGs) from ground-based submm cameras has revolutionised our understanding of galaxy evolution and star formation in extreme conditions. They are the strongest starbursts in the Universe approaching the Eddington limit and are believed to be the progenitors of the most massive galaxies today. However, theoretical models of galaxy evolution have even been challenged by a large number of detections of high-redshift SMGs. A very few among them are gravitationally lensed by an intervening galaxy. Recent wide-area extragalactic surveys have discovered hundreds of such strongly lensed SMGs, opening new exciting opportunities for observing the interstellar medium in these exceptional objects. We have thus carefully selected a sample of strongly gravitational lensed SMGs based on the submillimeter flux limit from the Herschel-ATLAS sample. Using IRAM telescopes, we have built a rich H2O-line-detected sample of 16 SMGs. We found a close-to-linear tight correlation between the H2O line and total infrared luminosity. This indicates the importance of far-IR pumping to the excitation of the H2O lines. Using a far-IR pumping model, we have derived the physical properties of the H2O gas and the dust. We showed that H2O lines trace a warm dense gas that may be closely related to the active star formation. Along with the H2O lines, several H2O+ lines have also been detected in three of our SMGs. We also find a tight correlation between the luminosity of the lines of H2O and H2O+ from local ULIRGs to high-redshift SMGs. The flux ratio between H2O+ and H2O suggests that cosmic rays from strong star forming activities are possibly driving the related oxygen chemistry. Another important common molecular gas tracer is the CO line. We have observed multiple transitions of the CO lines in each of our SMGs with IRAM 30m telescope. By analysing the CO line profile, we discovered a significant differential

  11. A search for faint high-redshift radio galaxy candidates at 150 MHz

    Science.gov (United States)

    Saxena, A.; Jagannathan, P.; Röttgering, H. J. A.; Best, P. N.; Intema, H. T.; Zhang, M.; Duncan, K. J.; Carilli, C. L.; Miley, G. K.

    2018-01-01

    Ultra-steep spectrum (USS) radio sources are good tracers of powerful radio galaxies at z > 2. Identification of even a single bright radio galaxy at z > 6 can be used to detect redshifted 21cm absorption due to neutral hydrogen in the intervening IGM. Here we describe a new sample of high-redshift radio galaxy (HzRG) candidates constructed from the TGSS ADR1 survey at 150 MHz. We employ USS selection (α ≤ -1.3) in ˜10000 square degrees, in combination with strict size selection and non-detections in all-sky optical and infrared surveys. We apply flux density cuts that probe a unique parameter space in flux density (50 < S150 < 200 mJy) to build a sample of 32 HzRG candidates. Follow-up Karl G. Jansky Very Large Array (VLA) observations at 1.4 GHz with an average beam size of 1.3 arcseconds (″) revealed ˜48% of sources to have a single radio component. P-band (370 MHz) imaging of 17 of these sources revealed a flattening radio SED for ten sources at low frequencies, which is expected from compact HzRGs. Two of our sources lie in fields where deeper multi-wavelength photometry and ancillary radio data are available and for one of these we find a best-fit photo-z of 4.8 ± 2.0. The other source has zphot = 1.4 ± 0.1 and a small angular size (3.7″), which could be associated with an obscured star forming galaxy or with a `dead' elliptical. One USS radio source not part of the HzRG sample but observed with the VLA nonetheless is revealed to be a candidate giant radio galaxy with a host galaxy photo-z of 1.8 ± 0.5, indicating a size of 875 kpc.

  12. Selection and Physical Properties of High-redshift Galaxies

    Science.gov (United States)

    Fang, G. W.

    2014-09-01

    Extremely Red Objects (EROs) and BzKs continue to attract considerable interest. It has been suggested that they may be the direct progenitors of present-day massive E/S0 galaxies, and can provide crucial constraints on the current galaxy formation and evolution models. Therefore, the key question is to measure the relative fraction of OGs (old galaxies) and DGs (young, and dusty starburst galaxies) in the sample of EROs. Many groups have been currently investigating the fractions of these two ERO populations using a variety of observational approaches, but the fraction of OGs and DGs from different surveys is different. In the meantime, a number of observations suggest that the epoch of z˜2 also plays an important role in galaxy formation and evolution for various reasons: the cosmic star formation rate density (SFRD) begins to drop at z˜2 from a flat plateau at higher redshifts; the morphological type mix of field galaxies changes remarkably at z˜2; the number density of QSOs has a peak at z˜2; and about 50% to 70% of the stellar mass assembly of galaxies took place in the redshift range 1UDF and COSMOS field, (2) a study on physical properties of passive and star-forming galaxies at z˜2 in the AEGIS field, and (3) the mid-infrared spectroscopy and multi-wavelength study of ultraluminous infrared galaxies (ULIRGs) at z˜2 in the AEGIS field. Chapter 1 gives a brief review on the research progresses of EROs at z˜1, BzKs at z˜2, and ULIRGs at z˜2, respectively. In Chapter 2 we present a quantitative study of the classification of EROs in the UDF and COSMOS field. Our sample includes 5264 (COSMOS, K_{Vega} ≤19.2) and 24 EROs (UDF, K_{Vega}≤22.0) with (i-K)_{AB}≥2.45. Using the fitting method of spectral energy distribution (SED), [3.6]-[8.0] color, and the nonparametric measures of galaxy morphology, we classify EROs into two classes: DGs and OGs. We find that the fraction of OGs and DGs in our sample (COSMOS) is similar, about 52% of them are DGs, and

  13. Dark-ages reionization and galaxy-formation simulation - VII. The sizes of high-redshift galaxies

    Science.gov (United States)

    Liu, Chuanwu; Mutch, Simon J.; Poole, Gregory B.; Angel, P. W.; Duffy, Alan R.; Geil, Paul M.; Mesinger, Andrei; Wyithe, J. Stuart B.

    2017-03-01

    We investigate high-redshift galaxy sizes using a semi-analytic model constructed for the Dark-ages Reionization And Galaxy-formation Observables from Numerical Simulation project. Our fiducial model, including strong feedback from supernovae and photoionization background, accurately reproduces the evolution of the stellar mass function and ultraviolet (UV) luminosity function. Using this model, we study the size-luminosity relation of galaxies and find that the effective radius scales with UV luminosity as Re ∝ L0.25 at z ∼ 5-9. We show that recently discovered very luminous galaxies at z ∼ 7 and 11 lie on our predicted size-luminosity relations. We find that a significant fraction of galaxies at z > 8 will not be resolved by James Webb Space Telescope, but Giant Magellan Telescope will have the ability to resolve all galaxies in haloes above the atomic cooling limit. We show that our fiducial model successfully reproduces the redshift evolution of average galaxy sizes at z > 5. We also explore galaxy sizes in models without supernova feedback. The no-supernova feedback models produce galaxy sizes that are smaller than observations. We therefore confirm that supernova feedback plays an important role in determining the size-luminosity relation of galaxies and its redshift evolution during reionization.

  14. Science from the Avo 1ST Light: the High Redshift Universe

    Science.gov (United States)

    Walton, Nicholas A.

    The Astrophysical Virtual Observatory science working group defined a number of key science drivers for which the AVO should develop capabilities. At the AVO's Jan 2003 'First Light' event the AVO prototype data access and manipulation tool was demonstrated. In particular its use in enabling discovery in deep multi wavelength data sets was highlighted. In this presentation I will describe how the AVO demonstrator has enabled investigation into the high redshift universe and in particular its use in discovering rare populations of high redshift galaxies from deep Hubble and ground based imaging data obtained through the Great Observatories Origins Deep Survey (GOODS) programme.

  15. A robust morphological classification of high-redshift galaxies using support vector machines on seeing limited images. I. Method description

    Science.gov (United States)

    Huertas-Company, M.; Rouan, D.; Tasca, L.; Soucail, G.; Le Fèvre, O.

    2008-02-01

    Context: Morphology is the most accessible tracer of the physical structure of galaxies, but its interpretation in the framework of galaxy evolution still remains a problem. Its dependence on wavelength renders the comparison between local and high redshift populations difficult. Furthermore, the quality of the measured morphology being strongly dependent on the image resolution, the comparison between different surveys is also a problem. Aims: We present a new non-parametric method to quantify morphologies of galaxies based on a particular family of learning machines called support vector machines. The method, which can be seen as a generalization of the classical C/A classification but with an unlimited number of dimensions and non-linear boundaries between decision regions, is fully automated and thus particularly well adapted to large cosmological surveys. The source code is available for download at http://www.lesia.obspm.fr/~huertas/galsvm.html Methods: To test the method, we use a seeing limited near-infrared (Ks band, 2,16 μm) sample observed with WIRCam at CFHT at a median redshift of z ~ 0.8. The machine is trained with a simulated sample built from a local visually classified sample from the SDSS, chosen in the high-redshift sample's rest-frame (i band, 0.77 μm) and artificially redshifted to match the observing conditions. We use a 12-dimensional volume, including 5 morphological parameters, and other characteristics of galaxies such as luminosity and redshift. A fraction of the simulated sample is used to test the machine and assess its accuracy. Results: We show that a qualitative separation in two main morphological types (late type and early type) can be obtained with an error lower than 20% up to the completeness limit of the sample (KAB ~ 22), which is more than 2 times better that what would be obtained with a classical C/A classification on the same sample and indeed comparable to space data. The method is optimized to solve a specific problem

  16. Are High-redshift Galaxies Hot? Temperature of z > 5 Galaxies and Implications for Their Dust Properties

    Science.gov (United States)

    Faisst, Andreas L.; Capak, Peter L.; Yan, Lin; Pavesi, Riccardo; Riechers, Dominik A.; Barišić, Ivana; Cooke, Kevin C.; Kartaltepe, Jeyhan S.; Masters, Daniel C.

    2017-09-01

    Recent studies have found a significant evolution and scatter in the relationship between the UV spectral slope (β UV) and the infrared excess (IRX; L IR/L UV) at z > 4, suggesting different dust properties of these galaxies. The total far-infrared (FIR) luminosity is key for this analysis, but it is poorly constrained in normal (main-sequence) star-forming z > 5 galaxies, where often only one single FIR point is available. To better inform estimates of the FIR luminosity, we construct a sample of local galaxies and three low-redshift analogues of z > 5 systems. The trends in this sample suggest that normal high-redshift galaxies have a warmer infrared (IR) spectral energy distribution (SED) compared to average z total FIR luminosities, which removes some tension between the dust attenuation models and observations of the IRX-β relation at z > 5. Despite this, some galaxies still fall below the minimum IRX-β relation derived with standard dust cloud models. We propose that radiation pressure in these highly star-forming galaxies causes a spatial offset between dust clouds and young star-forming regions within the lifetime of O/B stars. These offsets change the radiation balance and create viewing-angle effects that can change UV colors at fixed IRX. We provide a modified model that can explain the location of these galaxies on the IRX-β diagram.

  17. The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Molecular Gas Reservoirs in High-redshift Galaxies

    Science.gov (United States)

    Decarli, Roberto; Walter, Fabian; Aravena, Manuel; Carilli, Chris; Bouwens, Rychard; da Cunha, Elisabete; Daddi, Emanuele; Elbaz, David; Riechers, Dominik; Smail, Ian; Swinbank, Mark; Weiss, Axel; Bacon, Roland; Bauer, Franz; Bell, Eric F.; Bertoldi, Frank; Chapman, Scott; Colina, Luis; Cortes, Paulo C.; Cox, Pierre; Gónzalez-López, Jorge; Inami, Hanae; Ivison, Rob; Hodge, Jacqueline; Karim, Alex; Magnelli, Benjamin; Ota, Kazuaki; Popping, Gergö; Rix, Hans-Walter; Sargent, Mark; van der Wel, Arjen; van der Werf, Paul

    2016-12-01

    We study the molecular gas properties of high-z galaxies observed in the ALMA Spectroscopic Survey (ASPECS) that targets an ˜1 arcmin2 region in the Hubble Ultra Deep Field (UDF), a blind survey of CO emission (tracing molecular gas) in the 3 and 1 mm bands. Of a total of 1302 galaxies in the field, 56 have spectroscopic redshifts and correspondingly well-defined physical properties. Among these, 11 have infrared luminosities {L}{IR}\\gt {10}11 {L}⊙ , i.e., a detection in CO emission was expected. Out of these, 7 are detected at various significance in CO, and 4 are undetected in CO emission. In the CO-detected sources, we find CO excitation conditions that are lower than those typically found in starburst/sub-mm galaxy/QSO environments. We use the CO luminosities (including limits for non-detections) to derive molecular gas masses. We discuss our findings in the context of previous molecular gas observations at high redshift (star formation law, gas depletion times, gas fractions): the CO-detected galaxies in the UDF tend to reside on the low-{L}{IR} envelope of the scatter in the {L}{IR}{--}{L}{CO}\\prime relation, but exceptions exist. For the CO-detected sources, we find an average depletion time of ˜1 Gyr, with significant scatter. The average molecular-to-stellar mass ratio ({M}{{H}2}/M *) is consistent with earlier measurements of main-sequence galaxies at these redshifts, and again shows large variations among sources. In some cases, we also measure dust continuum emission. On average, the dust-based estimates of the molecular gas are a factor ˜2-5× smaller than those based on CO. When we account for detections as well as non-detections, we find large diversity in the molecular gas properties of the high-redshift galaxies covered by ASPECS.

  18. Constraining omega from X-ray properties of clusters of galaxies at high redshifts

    DEFF Research Database (Denmark)

    Sadat, R.; Blanchard, A.; Oukbir, J.

    1997-01-01

    Properties of high redshift clusters are a fundamental source of information for cosmology. It has been shown by Oukbir and Blanchard (1997) that the combined knowledge of the redshift distribution of X-ray clusters of galaxies and the luminosity-temperature correlation, L-X - T-X, provides a pow...

  19. High-redshift Ly alpha emitters : clues on the Milky Way infancy

    NARCIS (Netherlands)

    Salvadori, Stefania; Dayal, Pratika; Ferrara, Andrea

    With the aim of determining if Milky Way (MW) progenitors could be identified as high-redshift Lyman Alpha Emitters (LAEs), we have derived the intrinsic properties of z approximate to 5.7 MW progenitors, which are then used to compute their observed Ly alpha luminosity, L(alpha), and equivalent

  20. Planck intermediate results XXXIX. The Planck list of high-redshift source candidates

    DEFF Research Database (Denmark)

    Ade, P. A. R.; Aghanim, N.; Arnaud, M.

    2016-01-01

    The Planck mission, thanks to its large frequency range and all-sky coverage, has a unique potential for systematically detecting the brightest, and rarest, submillimetre sources on the sky, including distant objects in the high-redshift Universe traced by their dust emission. A novel method, bas...

  1. The rest-frame submillimeter spectrum of high-redshift, dusty, star-forming galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Spilker, J. S.; Marrone, D. P. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Aguirre, J. E. [University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Aravena, M. [European Southern Observatory, Alonso de Cordova 3107, Casilla 19001 Vitacura Santiago (Chile); Ashby, M. L. N. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Béthermin, M. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Université Paris Diderot, CEA-Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Bradford, C. M. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Bothwell, M. S. [Cavendish Laboratory, University of Cambridge, JJ Thompson Ave, Cambridge CB3 0HA (United Kingdom); Brodwin, M. [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Carlstrom, J. E.; Crawford, T. M. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Chapman, S. C. [Dalhousie University, Halifax, Nova Scotia (Canada); De Breuck, C.; Gullberg, B. [European Southern Observatory, Karl Schwarzschild Straße 2, D-85748 Garching (Germany); Fassnacht, C. D. [Department of Physics, University of California, One Shields Avenue, Davis, CA 95616 (United States); Gonzalez, A. H. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Greve, T. R. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Hezaveh, Y. [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada); Holzapfel, W. L., E-mail: jspilker@as.arizona.edu [Department of Physics, University of California, Berkeley, CA 94720 (United States); and others

    2014-04-20

    We present the average rest-frame spectrum of high-redshift dusty, star-forming galaxies from 250 to 770 GHz. This spectrum was constructed by stacking Atacama Large Millimeter/submillimeter Array (ALMA) 3 mm spectra of 22 such sources discovered by the South Pole Telescope and spanning z = 2.0-5.7. In addition to multiple bright spectral features of {sup 12}CO, [C I], and H{sub 2}O, we also detect several faint transitions of {sup 13}CO, HCN, HNC, HCO{sup +}, and CN, and use the observed line strengths to characterize the typical properties of the interstellar medium of these high-redshift starburst galaxies. We find that the {sup 13}CO brightness in these objects is comparable to that of the only other z > 2 star-forming galaxy in which {sup 13}CO has been observed. We show that the emission from the high-critical density molecules HCN, HNC, HCO{sup +}, and CN is consistent with a warm, dense medium with T {sub kin} ∼ 55 K and n{sub H{sub 2}}≳10{sup 5.5} cm{sup –3}. High molecular hydrogen densities are required to reproduce the observed line ratios, and we demonstrate that alternatives to purely collisional excitation are unlikely to be significant for the bulk of these systems. We quantify the average emission from several species with no individually detected transitions, and find emission from the hydride CH and the linear molecule CCH for the first time at high redshift, indicating that these molecules may be powerful probes of interstellar chemistry in high-redshift systems. These observations represent the first constraints on many molecular species with rest-frame transitions from 0.4 to 1.2 mm in star-forming systems at high redshift, and will be invaluable in making effective use of ALMA in full science operations.

  2. LOW MASSES AND HIGH REDSHIFTS: THE EVOLUTION OF THE MASS-METALLICITY RELATION

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Alaina; Straughn, Amber [Astrophysics Science Division, Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States); Scarlata, Claudia; Bedregal, Alejandro G. [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Domínguez, Alberto; Siana, Brian; Masters, Daniel [Department of Physics and Astronomy, University of California, Riverside, Riverside, CA 92521 (United States); Malkan, Matthew; Ross, Nathaniel [Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095 (United States); Martin, Crystal L. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Atek, Hakim [Laboratoire d' astrophysique, École Polytechniuqe Fédérale de Lausanne, Observatoire de Sauverny, 1290 Versoix (Switzerland); Colbert, James W.; Rafelski, Marc [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Teplitz, Harry [Infrared Processing and Analysis Center, Caltech, Pasadena, CA 91125 (United States); Bunker, Andrew J. [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, OX1 3RH (United Kingdom); Dressler, Alan; Hathi, Nimish; McCarthy, Patrick, E-mail: alaina.henry@nasa.gov [Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States)

    2013-10-20

    We present the first robust measurement of the high redshift mass-metallicity (MZ) relation at 10{sup 8} ∼< M/M {sub ☉} ∼< 10{sup 10}, obtained by stacking spectra of 83 emission-line galaxies with secure redshifts between 1.3 ∼< z ∼< 2.3. For these redshifts, infrared grism spectroscopy with the Hubble Space Telescope Wide Field Camera 3 is sensitive to the R {sub 23} metallicity diagnostic: ([O II] λλ3726, 3729 + [O III] λλ4959, 5007)/Hβ. Using spectra stacked in four mass quartiles, we find a MZ relation that declines significantly with decreasing mass, extending from 12+log(O/H) = 8.8 at M = 10{sup 9.8} M {sub ☉}, to 12+log(O/H) = 8.2 at M = 10{sup 8.2} M {sub ☉}. After correcting for systematic offsets between metallicity indicators, we compare our MZ relation to measurements from the stacked spectra of galaxies with M ∼> 10{sup 9.5} M {sub ☉} and z ∼ 2.3. Within the statistical uncertainties, our MZ relation agrees with the z ∼ 2.3 result, particularly since our somewhat higher metallicities (by around 0.1 dex) are qualitatively consistent with the lower mean redshift (z = 1.76) of our sample. For the masses probed by our data, the MZ relation shows a steep slope which is suggestive of feedback from energy-driven winds, and a cosmological downsizing evolution where high mass galaxies reach the local MZ relation at earlier times. In addition, we show that our sample falls on an extrapolation of the star-forming main sequence (the SFR-M {sub *} relation) at this redshift. This result indicates that grism emission-line selected samples do not have preferentially high star formation rates (SFRs). Finally, we report no evidence for evolution of the mass-metallicity-SFR plane; our stack-averaged measurements show excellent agreement with the local relation.

  3. High-redshift Post-starburst Galaxies from the Sloan Digital Sky Survey

    Science.gov (United States)

    Pattarakijwanich, Petchara

    in the same object. Given that AGN feedback is thought to be a likely mechanism responsible for quenching star-formation, post-starburst quasars provide ideal laboratory for studying this link. We explored various ways to identify post-starburst quasars, and construct our sample with more than 600 objects at high-redshift. This is the largest sample of post-starburst quasars available in the literature, and will be useful for AGN feedback studies. Finally, we studied the clustering properties of post-starburst galaxies through cross-correlation with CMASS galaxies. The real-space cross correlation function is a power-law with correlation length r0 ˜ 9.2 Mpc, and power-law index gamma ˜ 1.8. We also measure the linear bias of post-starburst galaxies to be bPSG ˜ 1.74 at redshift z = 0.62, corresponding to a dark matter halo mass of Mhalo ˜ 1.5 x 1013 M [special characters removed]. We found no evidence for redshift evolution in clustering properties for post-starburst galaxies.

  4. Detecting Massive, High-Redshift Galaxy Clusters Using the Thermal Sunyaev-Zel'dovich Effect

    Science.gov (United States)

    Adams, Carson; Steinhardt, Charles L.; Loeb, Abraham; Karim, Alexander; Staguhn, Johannes; Erler, Jens; Capak, Peter L.

    2017-01-01

    We develop the thermal Sunyaev-Zel'dovich (SZ) effect as a direct astrophysical measure of the mass distribution of dark matter halos. The SZ effect increases with cosmological distance, a unique astronomical property, and is highly sensitive to halo mass. We find that this presents a powerful methodology for distinguishing between competing models of the halo mass function distribution, particularly in the high-redshift domain just a few hundred million years after the Big Bang. Recent surveys designed to probe this epoch of initial galaxy formation such as CANDELS and SPLASH report an over-abundance of highly massive halos as inferred from stellar ultraviolet (UV) luminosities and the stellar mass to halo mass ratio estimated from nearby galaxies. If these UV luminosity to halo mass relations hold to high-redshift, observations estimate several orders of magnitude more highly massive halos than predicted by hierarchical merging and the standard cosmological paradigm. Strong constraints on the masses of these galaxy clusters are essential to resolving the current tension between observation and theory. We conclude that detections of thermal SZ sources are plausible at high-redshift only for the halo masses inferred from observation. Therefore, future SZ surveys will provide a robust determination between theoretical and observational predictions.

  5. Lyman Break Analogs: Constraints on the Formation of Extreme Starbursts at Low and High Redshift

    Science.gov (United States)

    Goncalves, Thiago S.; Overzier, Roderik; Basu-Zych, Antara; Martin, D. Christopher

    2011-01-01

    Lyman Break Analogs (LBAs), characterized by high far-UV luminosities and surface brightnesses as detected by GALEX, are intensely star-forming galaxies in the low-redshift universe (z approximately equal to 0.2), with star formation rates reaching up to 50 times that of the Milky Way. These objects present metallicities, morphologies and other physical properties similar to higher redshift Lyman Break Galaxies (LBGs), motivating the detailed study of LBAs as local laboratories of this high-redshift galaxy population. We present results from our recent integral-field spectroscopy survey of LBAs with Keck/OSIRIS, which shows that these galaxies have the same nebular gas kinematic properties as high-redshift LBGs. We argue that such kinematic studies alone are not an appropriate diagnostic to rule out merger events as the trigger for the observed starburst. Comparison between the kinematic analysis and morphological indices from HST imaging illustrates the difficulties of properly identifying (minor or major) merger events, with no clear correlation between the results using either of the two methods. Artificial redshifting of our data indicates that this problem becomes even worse at high redshift due to surface brightness dimming and resolution loss. Whether mergers could generate the observed kinematic properties is strongly dependent on gas fractions in these galaxies. We present preliminary results of a CARMA survey for LBAs and discuss the implications of the inferred molecular gas masses for formation models.

  6. Dark-ages reionization and galaxy formation simulation-XI. Clustering and halo masses of high redshift galaxies

    Science.gov (United States)

    Park, Jaehong; Kim, Han-Seek; Liu, Chuanwu; Trenti, Michele; Duffy, Alan R.; Geil, Paul M.; Mutch, Simon J.; Poole, Gregory B.; Mesinger, Andrei; Wyithe, J. Stuart B.

    2017-12-01

    We investigate the clustering properties of Lyman-break galaxies (LBGs) at z ∼ 6 - 8. Using the semi-analytical model MERAXES constructed as part of the dark-ages reionization and galaxy-formation observables from numerical simulation (DRAGONS) project, we predict the angular correlation function (ACF) of LBGs at z ∼ 6 - 8. Overall, we find that the predicted ACFs are in good agreement with recent measurements at z ∼ 6 and z ∼ 7.2 from observations consisting of the Hubble eXtreme Deep Field, the Hubble Ultra Deep Field and cosmic sssembly near-infrared deep extragalactic legacy survey field. We confirm the dependence of clustering on luminosity, with more massive dark matter haloes hosting brighter galaxies, remains valid at high redshift. The predicted galaxy bias at fixed luminosity is found to increase with redshift, in agreement with observations. We find that LBGs of magnitude MAB(1600) < -19.4 at 6 ≲ z ≲ 8 reside in dark matter haloes of mean mass ∼1011.0-1011.5 M⊙, and this dark matter halo mass does not evolve significantly during reionisation.

  7. Using r-process enhanced galaxies to estimate the neutron star merger rate at high redshift

    Science.gov (United States)

    Roederer, Ian

    2018-01-01

    The rapid neutron-capture process, or r-process, is one of the fundamental ways that stars produce heavy elements. I describe a new approach that uses the existence of r-process enhanced galaxies, like the recently discovered ultra-faint dwarf galaxy Reticulum II, to derive a rate for neutron star mergers at high redshift. This method relies on three assertions. First, several lines of reasoning point to neutron star mergers as a rare yet prolific producer of r-process elements, and one merger event is capable of enriching most of the stars in a low-mass dwarf galaxy. Second, the Local Group is cosmologically representative of the halo mass function at the mass scales of low-luminosity dwarf galaxies, and the volume that their progenitors spanned at high redshifts can be estimated from simulations. Third, many of these dwarf galaxies are extremely old, and the metals found in their stars today date from the earliest times at high redshift. These galaxies occupy a quantifiable volume of the Universe, from which the frequency of r-process enhanced galaxies can be estimated. This frequency may be interpreted as lower limit to the neutron star merger rate at a redshift (z ~ 5-10) that is much higher than is accessible to gravitational wave observatories. I will present a proof of concept demonstration using medium-resolution multi-object spectroscopy from the Michigan/Magellan Fiber System (M2FS) to recover the known r-process galaxy Reticulum II, and I will discuss future plans to apply this method to other Local Group dwarf galaxies.

  8. The fate of high redshift massive compact galaxies in dense environments

    Energy Technology Data Exchange (ETDEWEB)

    Kaufmann, Tobias; /Zurich, ETH; Mayer, Lucio; /Zurich U.; Carollo, Marcella; /Zurich, ETH; Feldmann, Robert; /Fermilab /Chicago U., KICP

    2012-01-01

    Massive compact galaxies seem to be more common at high redshift than in the local universe, especially in denser environments. To investigate the fate of such massive galaxies identified at z {approx} 2 we analyse the evolution of their properties in three cosmological hydrodynamical simulations that form virialized galaxy groups of mass {approx} 10{sup 13} M{sub {circle_dot}} hosting a central massive elliptical/S0 galaxy by redshift zero. We find that at redshift {approx} 2 the population of galaxies with M{sub *} > 2 x 10{sup 10} M{sub {circle_dot}} is diverse in terms of mass, velocity dispersion, star formation and effective radius, containing both very compact and relatively extended objects. In each simulation all the compact satellite galaxies have merged into the central galaxy by redshift 0 (with the exception of one simulation where one of such satellite galaxy survives). Satellites of similar mass at z = 0 are all less compact than their high redshift counterparts. They form later than the galaxies in the z = 2 sample and enter the group potential at z < 1, when dynamical friction times are longer than the Hubble time. Also, by z = 0 the central galaxies have increased substantially their characteristic radius via a combination of in situ star formation and mergers. Hence in a group environment descendants of compact galaxies either evolve towards larger sizes or they disappear before the present time as a result of the environment in which they evolve. Since the group-sized halos that we consider are representative of dense environments in the {Lambda}CDM cosmology, we conclude that the majority of high redshift compact massive galaxies do not survive until today as a result of the environment.

  9. Local Counterparts to High-Redshift Turbulent Galaxies: What are the Stellar Kinematics?

    Science.gov (United States)

    Bassett, Robert; Glazebrook, Karl; Fisher, David; Abraham, Roberto; Damjanov, Ivana

    2014-02-01

    We aim to measure the stellar kinematics of 4 low redshift turbulent, clumpy disks with the GMOS IFU. Recent observations of high redshift galaxies show that gaseous disks in high redshift (z 2) galaxies are turbulent. The source of this turbulence remains an open question. A possible scenario is that turbulent disks are fed by streams of cold gas, flowing along cosmic filaments, which drive the large H-alpha velocity dispersions and clumpy star formation observed (for example by the SINS survey). However, the recent discovery of low redshift disk galaxies with clumpy-high velocity dispersion disks shows that galaxies with similar properties to high-z clumpy disks can exists in absence of cold flows, therefore an alternate driver for turbulence seems likely to explain, at least these nearby galaxies. A contrasting scenario is that the turbulence is driven by feedback from extreme star formation originating from a thin stellar disk. These nearby star forming disks are very rare, yet they provide an oppurtunity to study clumpy disks with techniques which are impossible at high redshift (due to both resolution and surface brightness dimming). Here we propose one such study, to measure the stellar kinematics from Balmer absorption lines. If the stars and gas have similar velocity dispersion, this would favor externally driven turbulence by gas accretion (a rare thing in the low redshift Universe); conversely if the gas and stars have different dynamics then this would suggest that internally driven turbelence from feedback is a plausible scenario. We currently have GMOS IFU observations of two disk systems, and we propose here to extend our sample. To identify galaxies as disks we use lower resolution IFU emission line kinematics from AAO, surface photometry from UKIDSS and SDSS, and Halpha maps from Hubble Space Telescope.

  10. FINDING HIGH-REDSHIFT DARK STARS WITH THE JAMES WEBB SPACE TELESCOPE

    OpenAIRE

    Zackrisson, Erik; Scott, Pat; Rydberg, Claes-Erik; Iocco, Fabio; Edvardsson, Bengt; Ostlin, Goran; Sivertsson, Sofia; Zitrin, Adi; Broadhurst, Tom; Gondolo, Paolo

    2010-01-01

    The first stars in the history of the universe are likely to form in the dense central regions of similar to 10(5)-10(6) M-circle dot cold dark matter halos at z approximate to 10-50. The annihilation of dark matter particles in these environments may lead to the formation of so-called dark stars, which are predicted to be cooler, larger, more massive, and potentially more long-lived than conventional population III stars. Here, we investigate the prospects of detecting high-redshift dark sta...

  11. Hubble Space Telescope ACS Imaging of the GOALS Sample: Quantitative Structural Properties of Nearby Luminous Infrared Galaxies with L IR > 1011.4 L ⊙

    Science.gov (United States)

    Kim, D.-C.; Evans, A. S.; Vavilkin, T.; Armus, L.; Mazzarella, J. M.; Sheth, K.; Surace, J. A.; Haan, S.; Howell, J. H.; Díaz-Santos, T.; Petric, A.; Iwasawa, K.; Privon, G. C.; Sanders, D. B.

    2013-05-01

    A Hubble Space Telescope/Advanced Camera for Surveys study of the structural properties of 85 luminous and ultraluminous (L IR > 1011.4 L ⊙) infrared galaxies (LIRGs and ULIRGs) in the Great Observatories All-sky LIRG Survey (GOALS) sample is presented. Two-dimensional GALFIT analysis has been performed on F814W "I-band" images to decompose each galaxy, as appropriate, into bulge, disk, central point-spread function (PSF) and stellar bar components. The fraction of bulge-less disk systems is observed to be higher in LIRGs (35%) than in ULIRGs (20%), with the disk+bulge systems making up the dominant fraction of both LIRGs (55%) and ULIRGs (45%). Further, bulge+disk systems are the dominant late-stage merger galaxy type and are the dominant type for LIRGs and ULIRGs at almost every stage of galaxy-galaxy nuclear separation. The mean I-band host absolute magnitude of the GOALS galaxies is -22.64 ± 0.62 mag (1.8^{+1.4}_{-0.4} L^*_I), and the mean bulge absolute magnitude in GOALS galaxies is about 1.1 mag fainter than the mean host magnitude. Almost all ULIRGs have bulge magnitudes at the high end (-20.6 to -23.5 mag) of the GOALS bulge magnitude range. Mass ratios in the GOALS binary systems are consistent with most of the galaxies being the result of major mergers, and an examination of the residual-to-host intensity ratios in GOALS binary systems suggests that smaller companions suffer more tidal distortion than the larger companions. We find approximately twice as many bars in GOALS disk+bulge systems (32.8%) than in pure-disk mergers (15.9%) but most of the disk+bulge systems that contain bars are disk-dominated with small bulges. The bar-to-host intensity ratio, bar half-light radius, and bar ellipticity in GOALS galaxies are similar to those found in nearby spiral galaxies. The fraction of stellar bars decreases toward later merger stages and smaller nuclear separations, indicating that bars are destroyed as the merger advances. In contrast, the fraction of

  12. The radio properties of infrared-faint radio sources

    Science.gov (United States)

    Middelberg, E.; Norris, R. P.; Hales, C. A.; Seymour, N.; Johnston-Hollitt, M.; Huynh, M. T.; Lenc, E.; Mao, M. Y.

    2011-02-01

    Context. Infrared-faint radio sources (IFRS) are objects that have flux densities of several mJy at 1.4 GHz, but that are invisible at 3.6 μm when using sensitive Spitzer observations with μJy sensitivities. Their nature is unclear and difficult to investigate since they are only visible in the radio. Aims: High-resolution radio images and comprehensive spectral coverage can yield constraints on the emission mechanisms of IFRS and can give hints to similarities with known objects. Methods: We imaged a sample of 17 IFRS at 4.8 GHz and 8.6 GHz with the Australia Telescope Compact Array to determine the structures on arcsecond scales. We added radio data from other observing projects and from the literature to obtain broad-band radio spectra. Results: We find that the sources in our sample are either resolved out at the higher frequencies or are compact at resolutions of a few arcsec, which implies that they are smaller than a typical galaxy. The spectra of IFRS are remarkably steep, with a median spectral index of -1.4 and a prominent lack of spectral indices larger than -0.7. We also find that, given the IR non-detections, the ratio of 1.4 GHz flux density to 3.6 μm flux density is very high, and this puts them into the same regime as high-redshift radio galaxies. Conclusions: The evidence that IFRS are predominantly high-redshift sources driven by active galactic nuclei (AGN) is strong, even though not all IFRS may be caused by the same phenomenon. Compared to the rare and painstakingly collected high-redshift radio galaxies, IFRS appear to be much more abundant, but less luminous, AGN-driven galaxies at similar cosmological distances.

  13. The Main Sequences of Star-forming Galaxies and Active Galactic Nuclei at High Redshift

    Science.gov (United States)

    Mancuso, C.; Lapi, A.; Shi, J.; Cai, Z.-Y.; Gonzalez-Nuevo, J.; Béthermin, M.; Danese, L.

    2016-12-01

    We provide a novel, unifying physical interpretation on the origin, average shape, scatter, and cosmic evolution for the main sequences of star-forming galaxies and active galactic nuclei (AGNs) at high redshift z≳ 1. We achieve this goal in a model-independent way by exploiting: (i) the redshift-dependent star formation rate functions based on the latest UV/far-IR data from HST/Herschel, and related statistics of strong gravitationally lensed sources; (ii) deterministic evolutionary tracks for the history of star formation and black hole accretion, gauged on a wealth of multiwavelength observations including the observed Eddington ratio distribution. We further validate these ingredients by showing their consistency with the observed galaxy stellar mass functions and AGN bolometric luminosity functions at different redshifts via the continuity equation approach. Our analysis of the main sequence for high-redshift galaxies and AGNs highlights that the present data are consistently interpreted in terms of an in situ coevolution scenario for star formation and black hole accretion, envisaging these as local, time-coordinated processes.

  14. Dust Formation, Evolution, and Obscuration Effects in the Very High-Redshift Universe

    Science.gov (United States)

    Dwek, Eli; Staguhn, Johannes; Arendt, Richard G.; Kovacs, Attila; Su, Ting; Benford, Dominic J.

    2014-01-01

    The evolution of dust at redshifts z > or approx. 9, and consequently the dust properties, differs greatly from that in the local universe. In contrast to the local universe, core collapse supernovae (CCSNe) are the only source of thermally-condensed dust. Because of the low initial dust-to-gas mass ratio, grain destruction rates are low, so that CCSNe are net producers of interstellar dust. Galaxies with large initial gas mass or high mass infall rate will therefore have a more rapid net rate of dust production comported to galaxies with lower gas mass, even at the same star formation rate. The dust composition is dominated by silicates, which exhibit a strong rise in the UV opacity near the Lyman break. This "silicate-UV break" may be confused with the Lyman break, resulting in a misidentification of a galaxies' photometric redshift. In this paper we demonstrate these effects by analyzing the spectral energy distribution (SED) of MACS1149-JD, a lensed galaxy at z = 9.6. A potential 2mm counterpart of MACS1149-JD has been identified with GISMO. While additional observations are required to corroborate this identification, we use this possible association to illustrate the physical processes and the observational effects of dust in the very high redshift universe. Subject headings: galaxies: high-redshift - galaxies: evolution - galaxies: individual (MACS1149- JD) - Interstellar medium (ISM), nebulae: dust, extinction - physical data and processes: nuclear reactions, nucleosynthesis, abundances.

  15. Highlights And Shadows Of High Redshift Starbursts: A Herschel­Fmos Joint Effort

    Science.gov (United States)

    Puglisi, Annagrazia

    2017-06-01

    Starburst galaxies represent a critical stage in galaxy evolution as they are the likely progenitors of passively evolving ellipticals. The properties of high-redshift starbursts are however still debated as it is not clear to which extent their vigorous star formation rate is caused by an enhanced gas fraction or an enhanced star formation efficiency, and what physical processes trigger such violent activity. Our study of the rest-frame optical spectra from the FMOS-COSMOS survey of twelve z 1.6 Herschel starbursts combined with a rich ancillary data-set from UV to ALMA, is shedding light on some of these questions. By measuring the nebular extinction from different indicators, we find that 90% of their extreme SFR arises from an heavily obscured component which is thick in the optical. We also measure their gas-phase metallicity, showing that starbursts are metal-rich outliers from the metallicity-SFR anticorrelation observed at fixed stellar mass for the main sequence population. Our findings are consistent with a major merger origin for the starburst event. I will present this study discussing its implications on our interpretation of the high-redshift starbursts physics. I will also briefly discuss possible extensions of this work with the future PFS survey and how we can take advantage of the IFU capabilities of JWST/NIRspec to unveil the complex structure of these elusive systems.

  16. Five New High-Redshift Quasar Lenses from the Sloan Digital Sky Survey

    Energy Technology Data Exchange (ETDEWEB)

    Inada, Naohisa; Oguri, Masamune; Shin, Min-Su; Kayo, Issha; Strauss, Michael A.; Morokuma, Tomoki; Schneider, Donald P.; Becker, Robert H.; Bahcall, Neta A.; York, Donald G.

    2008-09-08

    We report the discovery of five gravitationally lensed quasars from the Sloan Digital Sky Survey (SDSS). All five systems are selected as two-image lensed quasar candidates from a sample of high-redshift (z > 2.2) SDSS quasars. We confirmed their lensing nature with additional imaging and spectroscopic observations. The new systems are SDSS J0819+5356 (source redshift z{sub s} = 2.237, lens redshift z{sub l} = 0.294, and image separation {theta} = 4.04 inch), SDSS J1254+2235 (z{sub s} = 3.626, {theta} = 1.56 inch), SDSS J1258+1657 (z{sub s} = 2.702, {theta} = 1.28 inch), SDSS J1339+1310 (z{sub s} = 2.243, {theta} = 1.69 cin), and SDSS J1400+3134 (z{sub s} = 3.317, {theta} = 1.74 inch). We estimate the lens redshifts of the latter four systems to be z{sub l} = 0.4-0.6 from the colors and magnitudes of the lensing galaxies. We find that the image configurations of all systems are well reproduced by standard mass models. Although these lenses will not be included in our statistical sample of z{sub s} < 2.2 lenses, they expand the number of lensed quasars which can be used for high-redshift galaxy and quasar studies.

  17. Selection Effects in the Study of High-Redshift Galaxy Morphology

    Science.gov (United States)

    Elmegreen, Debra M.; Elmegreen, B.

    2010-05-01

    Selection effects from bandshifting, angular resolution limitations, surface brightness dimming, and intergalactic absorption skew our view of high redshift galaxies so that we primarily see those that are extremely bright, massive, and star-bursting. Bandshifting shows a galaxy in its restframe NUV or FUV at z>1, and also biases the determination of age from BViz colors to lower values. The rapid increase in resolvable physical size with redshift for zUDF) noise by redshift z 2. Intergalactic absorption further decreases the brightness of galaxies by factors of a few at this z. These effects combine to make the average star formation rate in an observable clump increase as (1+z)8 for z<1. None of these selection effects directly causes the clump mass to increase with redshift in clumpy galaxies, however. Clumps are well separated from each other and they show up over a wide range of wavelengths. The increase in clump mass with redshift is mostly from an increase in observable galaxy mass. This is because there is a nearly constant ratio of clump mass to galaxy luminosity and the primary selection effect is for bright galaxies, considering that the intrinsic surface brightness for anything observable increases sharply with z. Redshifted versions of local grand design, multiple arm, and flocculent spiral galaxies, along with dwarf irregulars and interacting galaxies, will be shown to indicate which features are observable at high redshift.

  18. The High-redshift Clusters Occupied by Bent Radio AGN (COBRA) Survey: The Spitzer Catalog

    Science.gov (United States)

    Paterno-Mahler, R.; Blanton, E. L.; Brodwin, M.; Ashby, M. L. N.; Golden-Marx, E.; Decker, B.; Wing, J. D.; Anand, G.

    2017-07-01

    We present 190 galaxy cluster candidates (most at high redshift) based on galaxy overdensity measurements in the Spitzer/IRAC imaging of the fields surrounding 646 bent, double-lobed radio sources drawn from the Clusters Occupied by Bent Radio AGN (COBRA) Survey. The COBRA sources were chosen as objects in the Very Large Array FIRST survey that lack optical counterparts in the Sloan Digital Sky Survey to a limit of m r = 22, making them likely to lie at high redshift. This is confirmed by our observations: the redshift distribution of COBRA sources with estimated redshifts peaks near z = 1 and extends out to z≈ 3. Cluster candidates were identified by comparing our target fields to a background field and searching for statistically significant (≥slant 2σ ) excesses in the galaxy number counts surrounding the radio sources; 190 fields satisfy the ≥slant 2σ limit. We find that 530 fields (82.0%) have a net positive excess of galaxies surrounding the radio source. Many of the fields with positive excesses but below the 2σ cutoff are likely to be galaxy groups. Forty-one COBRA sources are quasars with known spectroscopic redshifts, which may be tracers of some of the most distant clusters known.

  19. Feeding cosmic star formation: exploring high-redshift molecular gas with CO intensity mapping

    Science.gov (United States)

    Breysse, Patrick C.; Rahman, Mubdi

    2017-06-01

    The study of molecular gas is crucial for understanding star formation, feedback and the broader ecosystem of a galaxy as a whole. However, we have limited understanding of its physics and distribution in all but the nearest galaxies. We present a new technique for studying the composition and distribution of molecular gas in high-redshift galaxies inaccessible to existing methods. Our proposed approach is an extension of carbon monoxide intensity mapping methods, which have garnered significant experimental interest in recent years. These intensity mapping surveys target the 115 GHz 12CO (1-0) line, but also contain emission from the substantially fainter 110 GHz 13CO (1-0) transition. The method leverages the information contained in the 13CO line by cross-correlating pairs of frequency channels in an intensity mapping survey. Since 13CO is emitted from the same medium as the 12CO, but saturates at a much higher column density, this cross-correlation provides valuable information about both the gas density distribution and isotopologue ratio, inaccessible from the 12CO alone. Using a simple model of these molecular emission lines, we show that a future intensity mapping survey can constrain the abundance ratio of these two species and the fraction of emission from optically thick regions to order ˜30 per cent. These measurements cannot be made by traditional CO observations, and consequently the proposed method will provide unique insight into the physics of star formation, feedback and galactic ecology at high redshifts.

  20. Quantitative Morphology of High-Redshift Galaxies Using GALEX Ultraviolet Images of Nearby Galaxies

    Directory of Open Access Journals (Sweden)

    Bum-Suk Yeom

    2017-09-01

    Full Text Available We present simulations of the optical-band images of high-redshift galaxies utilizing 845 near-ultraviolet (NUV images of nearby galaxies obtained through the Galaxy Evolution Explorer (GALEX. We compute the concentration (C, asymmetry (A, Gini (G, and M20 parameters of the GALEX NUV/Sloan Digital Sky Survey r-band images at z ~ 0 and their artificially redshifted optical images at z = 0.9 and 1.6 in order to quantify the morphology of galaxies at local and high redshifts. The morphological properties of nearby galaxies in the NUV are presented using a combination of morphological parameters, in which earlytype galaxies are well separated from late-type galaxies in the G–M20, C–M20, A–C, and A–M20 planes. Based on the distribution of galaxies in the A–C and G–M20 planes, we examine the morphological K-correction (i.e., cosmological distance effect and bandshift effect. The cosmological distance effect on the quantitative morphological parameters is found to be significant for early-type galaxies, while late-type galaxies are more greatly affected by the bandshift effect. Knowledge of the morphological K-correction will set the foundation for forthcoming studies on understanding the quantitative assessment of galaxy evolution.

  1. AWAKENING OF THE HIGH-REDSHIFT BLAZAR CGRaBS J0809+5341

    Energy Technology Data Exchange (ETDEWEB)

    Paliya, Vaidehi S.; Stalin, C. S. [Indian Institute of Astrophysics, Block II, Koramangala, Bangalore 560034 (India); Parker, M. L.; Fabian, A. C. [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Ramya, S. [Shanghai Astronomical Observatory, 80 Nandan Road, Shanghai 200030 (China); Covino, S.; Tagliaferri, G. [INAF-Osservatorio Astronomico di Brera, Via Bianchi 46, I-23807 Merate (Italy); Sahayanathan, S. [Astrophysical Sciences Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Ravikumar, C. D., E-mail: vaidehi@iiap.res.in [Department of Physics, University of Calicut, Malappuram 673635 (India)

    2015-04-20

    CGRaBS J0809+5341, a high-redshift blazar at z = 2.144, underwent a giant optical outburst on 2014 April 19 when it brightened by ∼5 mag and reached an unfiltered apparent magnitude of 15.7 mag. This implies an absolute magnitude of −30.5 mag, making it one of the brightest quasars in the universe. This optical flaring triggered us to carry out observations during the decaying part of the flare covering a wide energy range using the Nuclear Spectroscopic Telescope Array, Swift, and ground-based optical facilities. For the first time, the source is detected in γ-rays by the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope. A high optical polarization of ∼10% is also observed. Using the Sloan Digital Sky Survey spectrum, the accretion disk luminosity and black hole mass are estimated as 1.5 × 10{sup 45} erg s{sup −1} and 10{sup 8.4} M{sub ⊙}, respectively. Using a single zone leptonic emission model, we reproduce the spectral energy distribution of the source during the flaring activity. This analysis suggests that the emission region is probably located outside the broad-line region, and the jet becomes radiatively efficient. We also show that the overall properties of CGRaBS J0809+5341 seem to not be in agreement with the general properties observed in high-redshift blazars up to now.

  2. Awakening of The High-Redshift Blazar CGRaBS J0809+5341

    Science.gov (United States)

    Paliya, Vaidehi S.; Parker, M. L.; Stalin, C. S.; Fabian, A. C.; Ramya, S.; Covino, S.; Tagliaferri, G.; Sahayanathan, S.; Ravikumar, C. D.

    2015-04-01

    CGRaBS J0809+5341, a high-redshift blazar at z = 2.144, underwent a giant optical outburst on 2014 April 19 when it brightened by ˜5 mag and reached an unfiltered apparent magnitude of 15.7 mag. This implies an absolute magnitude of -30.5 mag, making it one of the brightest quasars in the universe. This optical flaring triggered us to carry out observations during the decaying part of the flare covering a wide energy range using the Nuclear Spectroscopic Telescope Array, Swift, and ground-based optical facilities. For the first time, the source is detected in γ-rays by the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope. A high optical polarization of ˜10% is also observed. Using the Sloan Digital Sky Survey spectrum, the accretion disk luminosity and black hole mass are estimated as 1.5 × 1045 erg s-1 and 108.4 M⊙, respectively. Using a single zone leptonic emission model, we reproduce the spectral energy distribution of the source during the flaring activity. This analysis suggests that the emission region is probably located outside the broad-line region, and the jet becomes radiatively efficient. We also show that the overall properties of CGRaBS J0809+5341 seem to not be in agreement with the general properties observed in high-redshift blazars up to now.

  3. Shocks and Cool Cores: An ALMA View of Massive Galaxy Cluster Formation at High Redshifts

    Science.gov (United States)

    Basu, Kaustuv

    2017-07-01

    These slides present some recent results on the Sunyaev-Zel'dovich (SZ) effect imaging of galaxy cluster substructures. The advantage of SZ imaging at high redshifts or in the low density cluster outskirts is already well-known. Now with ALMA a combination of superior angular resolution and high sensitivity is available. One example is the first ALMA measurement of a merger shock at z=0.9 in the famous El Gordo galaxy cluster. Here comparison between SZ, X-ray and radio data enabled us to put constraints on the shock Mach number and magnetic field strength for a high-z radio relic. Second example is the ALMA SZ imaging of the core region of z=1.4 galaxy cluster XMMU J2235.2-2557. Here ALMA data provide an accurate measurement of the thermal pressure near the cluster center, and from a joint SZ/X-ray analysis we find clear evidence for a reduced core temperature. This result indicate that a cool core establishes itself early enough in the cluster formation history while the gas accumulation is still continuing. The above two ALMA measurements are among several other recent SZ results that shed light on the formation process of massive clusters at high redshifts.

  4. VizieR Online Data Catalog: VANDELS High-Redshift Galaxy Evolution (McLure+, 2017)

    Science.gov (United States)

    McLure, R.; Pentericci, L.; Vandels Team

    2017-11-01

    This is the first data release (DR1) of the VANDELS survey, an ESO public spectroscopy survey targeting the high-redshift Universe. The VANDELS survey uses the VIMOS spectrograph on ESO's VLT to obtain ultra-deep, medium resolution, optical spectra of galaxies within the UKIDSS Ultra Deep Survey (UDS) and Chandra Deep Field South (CDFS) survey fields (0.2 sq. degree total area). Using robust photometric redshift pre-selection, VANDELS is targeting ~2100 galaxies in the redshift interval 1.0=3. In addition, VANDELS is targeting a substantial number of passive galaxies in the redshift interval 1.0survey is obtaining ultra-deep optical spectroscopy with the VIMOS MR grism and GG475 order-sorting filter, which covers the wavelength range 4800-10000Å at a dispersion of 2.5Å/pix and a spectral resolution of R~600. Each galaxy receives between a minimum of 20-hours and a maximum of 80-hours of on-source integration time. The fundamental aim of the survey is to provide the high signal-to-noise spectra necessary to measure key physical properties such as stellar population ages, metallicities and outflow velocities from detailed absorption-line studies. By targeting two extra-galactic survey fields with superb multi-wavelength imaging data, VANDELS is designed to produce a unique legacy dataset for exploring the physics underpinning high-redshift galaxy evolution. (2 data files).

  5. The impact of star formation and gamma-ray burst rates at high redshift on cosmic chemical evolution and reionization

    Science.gov (United States)

    Vangioni, Elisabeth; Olive, Keith A.; Prestegard, Tanner; Silk, Joseph; Petitjean, Patrick; Mandic, Vuk

    2015-03-01

    Recent observations in the total luminosity density have led to significant progress in establishing the star formation rate (SFR) at high redshift. Concurrently observed gamma-ray burst rates have also been used to extract the SFR at high redshift. The SFR in turn can be used to make a host of predictions concerning the ionization history of the Universe, the chemical abundances, and supernova rates. We compare the predictions made using a hierarchical model of cosmic chemical evolution based on three recently proposed SFRs: two based on extracting the SFR from the observed gamma-ray burst rate at high redshift, and one based on the observed galaxy luminosity function at high redshift. Using the WMAP/Planck data on the optical depth and epoch of reionization, we find that only the SFR inferred from gamma-ray burst data at high redshift suffices to allow a single mode (in the initial mass function - IMF) of star formation which extends from z = 0 to redshifts >10. For the case of the SFR based on the observed galaxy luminosity function, the reionization history of the Universe requires a bimodal IMF which includes at least a coeval high- (or intermediate-) mass mode of star formation at high redshift (z > 10). Therefore, we also consider here a more general bimodal case which includes an early-forming high-mass mode as a fourth model to test the chemical history of the Universe. We conclude that observational constraints on the global metallicity and optical depth at high redshift favour unseen faint but active star-forming galaxies as pointed out in many recent studies.

  6. Observations of the Hubble Deep Field with the Infrared Space Observatory .4. Association of sources with Hubble Deep Field galaxies

    DEFF Research Database (Denmark)

    Mann, R.G.; Oliver, S.J.; Serjeant, S.B.G.

    1997-01-01

    We discuss the identification of sources detected by the Infrared Space Observatory (ISO) at 6.7 and 15 mu m in the Hubble Deep Field (HDF) region. We conservatively associate ISO sources with objects in existing optical and near-infrared HDF catalogues using the likelihood ratio method, confirmi...... and one star), Amongst optically bright HDF galaxies, ISO tends to detect luminous, star-forming galaxies at fairly high redshift and with disturbed morphologies, in preference to nearby ellipticals....... these results (and, in one case, clarifying them) with independent visual searches, We find 15 ISO sources to be reliably associated with bright [I-814(AB) galaxies in the HDF, and one with an I-814(AB)=19.9 star, while a further 11 are associated with objects in the Hubble Flanking Fields (10 galaxies...

  7. GRB 120521C at z ∼ 6 and the properties of high-redshift γ-ray bursts

    Energy Technology Data Exchange (ETDEWEB)

    Laskar, Tanmoy; Berger, Edo; Zauderer, B. Ashley; Margutti, Raffaella; Fong, Wen-fai [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Tanvir, Nial; Wiersema, Klaas [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Levan, Andrew [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Perley, Daniel [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Menten, Karl [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Hrudkova, Marie [Isaac Newton Group of Telescopes, Apartado de Correos 321, E-387 00 Santa Cruz de la Palma, Canary Islands (Spain)

    2014-01-20

    We present optical, near-infrared, and radio observations of the afterglow of GRB 120521C. By modeling the multi-wavelength data set, we derive a photometric redshift of z ≈ 6.0, which we confirm with a low signal-to-noise ratio spectrum of the afterglow. We find that a model with a constant-density environment provides a good fit to the afterglow data, with an inferred density of n ≲ 0.05 cm{sup –3}. The radio observations reveal the presence of a jet break at t {sub jet} ≈ 7 d, corresponding to a jet opening angle of θ{sub jet} ≈ 3°. The beaming-corrected γ-ray and kinetic energies are E {sub γ} ≈ E{sub K} ≈ 3 × 10{sup 50} erg. We quantify the uncertainties in our results using a detailed Markov Chain Monte Carlo analysis, which allows us to uncover degeneracies between the physical parameters of the explosion. To compare GRB 120521C to other high-redshift bursts in a uniform manner we re-fit all available afterglow data for the two other bursts at z ≳ 6 with radio detections (GRBs 050904 and 090423). We find a jet break at t {sub jet} ≈ 15 d for GRB 090423, in contrast to previous work. Based on these three events, we find that γ-ray bursts (GRBs) at z ≳ 6 appear to explode in constant-density environments, and exhibit a wide range of energies and densities that span the range inferred for lower redshift bursts. On the other hand, we find a hint for narrower jets in the z ≳ 6 bursts, potentially indicating a larger true event rate at these redshifts. Overall, our results indicate that long GRBs share a common progenitor population at least to z ∼ 8.

  8. High-Redshift Type Ia Supernova Rates in Galaxy Cluster and Field Environments

    Science.gov (United States)

    Barbary, Kyle Harris

    This thesis presents Type Ia supernova (SN Ia) rates from the Hubble Space Telescope (HST) Cluster Supernova Survey, a program designed to efficiently detect and observe high-redshift supernovae by targeting massive galaxy clusters at redshifts 0.9 z z > 0.9 SNe. The SN Ia rate is found to be 0.50+0.23-0.19 (stat) +0.10-0.09 (sys) h 702 SNuB (SNuB = 10-12 SNe Lsun,B-1 yr-1), or in units of stellar mass, 0.36+0.16-0.13 (stat) +0.07-0.06 (sys) h 702 SNuM (SNuM = 10-12 SNe M sun-1 yr-1). This represents a factor of approximately 5 +/- 2 increase over measurements of the cluster rate at z influence of younger stellar populations the rate is also calculated specifically in cluster red-sequence galaxies and in morphologically early-type galaxies, with results similar to the full cluster rate. Finally, the upper limit of one host-less cluster SN Ia detected in the survey implies that the fraction of stars in the intra-cluster medium is less than 0.47 (95% confidence), consistent with measurements at lower redshifts. The volumetric SN Ia rate can also be used to constrain the SN Ia delay time distribution. However, there have been discrepancies in recent analyses of both the high-redshift rate and its implications for the delay time distribution. Here, the volumetric SN Ia rate out to z ˜ 1.6 is measured, based on ˜12 SNe Ia in the foregrounds and backgrounds of the clusters targeted in the survey. The rate is measured in four broad redshift bins. The results are consistent with previous measurements at z > 1 and strengthen the case for a SN Ia rate that is greater than approximately 0.6 x 10-4 h70 3 yr-1 Mpc-3 at z ˜ 1 and flattening out at higher redshift. Assumptions about host-galaxy dust extinction used in different high-redshift rate measurements are examined. Different assumptions may account for some of the difference in published results for the z ˜ 1 rate.

  9. The SCUBA-2 850 μm Follow-up of WISE-selected, Luminous Dust-obscured Quasars

    Science.gov (United States)

    Fan, Lulu; Jones, Suzy F.; Han, Yunkun; Knudsen, Kirsten K.

    2017-12-01

    Hot dust-obscured galaxies (Hot DOGs) are a new population recently discovered in the Wide-field Infrared Survey Explorer All-Sky survey. Multiwavelength follow-up observations suggest that they are luminous, dust-obscured quasars at high redshift. Here we present the JCMT SCUBA-2 850 μm follow-up observations of 10 Hot DOGs. Four out of ten Hot DOGs have been detected at >3σ level. Based on the IR SED decomposition approach, we derive the IR luminosities of AGN torus and cold dust components. Hot DOGs in our sample are extremely luminous with most of them having {L}{IR}{tot}> {10}14 {L}⊙ . The torus emissions dominate the total IR energy output. However, the cold dust contribution is still non-negligible, with the fraction of the cold dust contribution to the total IR luminosity (˜8%-24%) being dependent on the choice of torus model. The derived cold dust temperatures in Hot DOGs are comparable to those in UV bright quasars with similar IR luminosity, but much higher than those in SMGs. Higher dust temperatures in Hot DOGs may be due to the more intense radiation field caused by intense starburst and obscured AGN activities. Fourteen and five submillimeter serendipitous sources in the 10 SCUBA-2 fields around Hot DOGs have been detected at >3σ and >3.5σ levels, respectively. By estimating their cumulative number counts, we confirm the previous argument that Hot DOGs lie in dense environments. Our results support the scenario in which Hot DOGs are luminous, dust-obscured quasars lying in dense environments, and being in the transition phase between extreme starburst and UV-bright quasars.

  10. VizieR Online Data Catalog: KMOS AGN Survey at High redshift (KASHz) (Harrison+, 2016)

    Science.gov (United States)

    Harrison, C. M.; Alexander, D. M.; Mullaney, J. R.; Stott, J. P.; Swinbank, A. M.; Arumugam, V.; Bauer, F. E.; Bower, R. G.; Bunker, A. J.; Sharples, R. M.

    2016-08-01

    KASHz is designed to ultimately obtain spatially resolved emission-line kinematics of ~(100-200) high-redshift (z~0.6-3.6) AGN. For our target selection we make use of deep X-ray surveys performed in extragalactic fields (COSMOS, see Scoville et al., 2007, Cat. J/ApJS/171/1; CDF-S, see Giacconi et al. 2001ApJ...551..624G and Xue et al., 2011, Cat. J/ApJS/195/10 (CDFS); UDS, SXDS: see Furusawa et al. 2008, Cat. J/ApJS/176/1 (UDS) and SSA22, see Steidel et al. 1998ApJ...492..428S). (1 data file).

  11. A new method to search for high-redshift clusters using photometric redshifts

    Energy Technology Data Exchange (ETDEWEB)

    Castignani, G.; Celotti, A. [SISSA, Via Bonomea 265, I-34136 Trieste (Italy); Chiaberge, M.; Norman, C., E-mail: castigna@sissa.it [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2014-09-10

    We describe a new method (Poisson probability method, PPM) to search for high-redshift galaxy clusters and groups by using photometric redshift information and galaxy number counts. The method relies on Poisson statistics and is primarily introduced to search for megaparsec-scale environments around a specific beacon. The PPM is tailored to both the properties of the FR I radio galaxies in the Chiaberge et al. sample, which are selected within the COSMOS survey, and to the specific data set used. We test the efficiency of our method of searching for cluster candidates against simulations. Two different approaches are adopted. (1) We use two z ∼ 1 X-ray detected cluster candidates found in the COSMOS survey and we shift them to higher redshift up to z = 2. We find that the PPM detects the cluster candidates up to z = 1.5, and it correctly estimates both the redshift and size of the two clusters. (2) We simulate spherically symmetric clusters of different size and richness, and we locate them at different redshifts (i.e., z = 1.0, 1.5, and 2.0) in the COSMOS field. We find that the PPM detects the simulated clusters within the considered redshift range with a statistical 1σ redshift accuracy of ∼0.05. The PPM is an efficient alternative method for high-redshift cluster searches that may also be applied to both present and future wide field surveys such as SDSS Stripe 82, LSST, and Euclid. Accurate photometric redshifts and a survey depth similar or better than that of COSMOS (e.g., I < 25) are required.

  12. COSMIC RAYS CAN DRIVE STRONG OUTFLOWS FROM GAS-RICH HIGH-REDSHIFT DISK GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Hanasz, M.; Kowalik, K.; Wóltański, D. [Centre for Astronomy, Nicolaus Copernicus University, Faculty of Physics, Astronomy and Informatics, Grudziadzka 5, PL-87100 Toruń (Poland); Lesch, H. [Universitäts-Sternwarte München, Scheinerstr. 1, D-81679 München (Germany); Naab, T. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching bei München (Germany); Gawryszczak, A., E-mail: mhanasz@astri.uni.torun.pl [Poznań Supercomputing and Networking Centre, ul. Noskowskiego 10, PL-61-704 Poznań (Poland)

    2013-11-10

    We present simulations of the magnetized interstellar medium (ISM) in models of massive star-forming (40 M {sub ☉} yr{sup –1}) disk galaxies with high gas surface densities (Σ{sub gas} ∼ 100 M {sub ☉} pc{sup –2}) similar to observed star-forming high-redshift disks. We assume that type II supernovae deposit 10% of their energy into the ISM as cosmic rays (CRs) and neglect the additional deposition of thermal energy or momentum. With a typical Galactic diffusion coefficient for CRs (3 × 10{sup 28} cm{sup 2} s{sup –1}), we demonstrate that this process alone can trigger the local formation of a strong low-density galactic wind maintaining vertically open field lines. Driven by the additional pressure gradient of the relativistic fluid, the wind speed can exceed 10{sup 3} km s{sup –1}, much higher than the escape velocity of the galaxy. The global mass loading, i.e., the ratio of the gas mass leaving the galactic disk in a wind to the star formation rate, becomes of order unity once the system has settled into an equilibrium. We conclude that relativistic particles accelerated in supernova remnants alone provide a natural and efficient mechanism to trigger winds similar to observed mass-loaded galactic winds in high-redshift galaxies. These winds also help in explaining the low efficiencies for the conversion of gas into stars in galaxies, as well as the early enrichment of the intergalactic medium with metals. This mechanism may be at least of similar importance to the traditionally considered momentum feedback from massive stars and thermal and kinetic feedback from supernova explosions.

  13. Gemini Spectroscopy of Supernovae from the Supernova Legacy Survey: Improving High-Redshift Supernova Selection and Classification

    Science.gov (United States)

    Howell, D. A.; Sullivan, M.; Perrett, K.; Bronder, T. J.; Hook, I. M.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Fabbro, S.; Fouchez, D.; Guy, J.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Knop, R.; McMahon, R. G.; Perlmutter, S.; Walton, N. A.

    2005-12-01

    We present new techniques for improving the efficiency of supernova (SN) classification at high redshift using 64 candidates observed at Gemini North and South during the first year of the Supernova Legacy Survey (SNLS). The SNLS is an ongoing 5 year project with the goal of measuring the equation of state of dark energy by discovering and following over 700 high-redshift SNe Ia using data from the Canada-France-Hawaii Telescope Legacy Survey. We achieve an improvement in the SN Ia spectroscopic confirmation rate: at Gemini 71% of candidates are now confirmed as SNe Ia, compared to 54% using the methods of previous surveys. This is despite the comparatively high redshift of this sample, in which the median SN Ia redshift is z=0.81 (0.155Berthelot, 75231 Paris Cedex 05, France. DSM/DAPNIA, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France.

  14. Dark-ages reionization and galaxy formation simulation - XIII. AGN quenching of high-redshift star formation in ZF-COSMOS-20115

    Science.gov (United States)

    Qin, Yuxiang; Mutch, Simon J.; Duffy, Alan R.; Geil, Paul M.; Poole, Gregory B.; Mesinger, Andrei; Wyithe, J. Stuart B.

    2017-11-01

    Massive quiescent galaxies (MQGs) are thought to have formed stars rapidly at early times followed by a long period of quiescence. The recent discovery of a MQG, ZF-COSMOS-20115 at z ˜ 4, only 1.5 Gyr after the big bang, places new constraints on galaxy growth and the role of feedback in early star formation. Spectroscopic follow-up confirmed ZF-COSMOS-20115 as a MQG at z = 3.717 with an estimated stellar mass of ˜1011 M⊙, showing no evidence of recent star formation. We use the Meraxes semi-analytic model to investigate how ZF-COSMOS-20115 analogues build stellar mass, and why they become quiescent. We identify three analogue galaxies with similar properties to ZF-COSMOS-20115. We find that ZF-COSMOS-20115 is likely hosted by a massive halo with virial mass of ˜1013 M⊙, having been through significant mergers at early times. These merger events drove intense growth of the nucleus, which later prevented cooling and quenched star formation. Therefore, ZF-COSMOS-20115 is unlikely to have experienced strong or extended star formation events at z black holes in our simulation and were luminous quasars at z ˜ 5, indicating that ZF-COSMOS-20115 and other MQGs may be the descendants of high-redshift quasars. In addition, the model suggests that ZF-COSMOS-20115 formed in a region of intergalactic medium that was reionized early.

  15. Origin of the spectral deformation in the near infrared radiation from Tore-Supra carbon components; Origine de la deformation spectrale de la luminance proche infrarouge des composants en carbone de Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Delchambre, E

    2004-03-01

    This work concerns the understanding of a physical phenomenon which is important for the future course of magnetic confinement fusion research: namely the anomalous deformation in the near infrared of radiation from tokamak plasma facing components under plasma particle impact. The goal of this work was to reproduce this phenomenon in laboratory experiments, characterize it and explain it, so that the measurements of the temperature of plasma facing components can be made with confidence. Laboratory experiments have been performed using an ECR ions source and a helicon plasma source. The spectral luminance deformation has been observed on graphite surface under electrons and ions bombardment and the amplitude of this phenomenon was found to depend on the type of material used and the power density of the incident particles. A systematic consideration and evaluation of alternative explanations for the observed spectral deformation has been made. A number of plausible interpretations has been considered and discarded as e.g. Bremsstrahlung radiation, or assigned a low probability as the luminescence effect. The possible partial transparency of the material has also been considered at some length, but finally discarded because the low thermal conductivity of the graphite materials under consideration does not permit a strong enough temperature gradient to cause the observed deformation. The possible explanation is reduced to the non uniform surface temperature due to the presence of hot spots during particle bombardment. This hypothesis implies that the measured luminance is the contribution of several temperatures. The measured spectral luminance deformation, basing on hot spots hypothesis, is simulated. This hypothesis allows to asses the surface temperature, the hot spots temperature and the hot spots coverage on the surface. These results are validated using a thermal model of dust in radiate equilibrium. This model allows us to deduce an average size of the dust

  16. The [CII] 158 μm line emission in high-redshift galaxies

    Science.gov (United States)

    Lagache, G.; Cousin, M.; Chatzikos, M.

    2018-02-01

    Gas is a crucial component of galaxies, providing the fuel to form stars, and it is impossible to understand the evolution of galaxies without knowing their gas properties. The [CII] fine structure transition at 158 μm is the dominant cooling line of cool interstellar gas, and is the brightest of emission lines from star forming galaxies from FIR through metre wavelengths, almost unaffected by attenuation. With the advent of ALMA and NOEMA, capable of detecting [CII]-line emission in high-redshift galaxies, there has been a growing interest in using the [CII] line as a probe of the physical conditions of the gas in galaxies, and as a star formation rate (SFR) indicator at z ≥ 4. In this paper, we have used a semi-analytical model of galaxy evolution (G.A.S.) combined with the photoionisation code CLOUDY to predict the [CII] luminosity of a large number of galaxies (25 000 at z ≃ 5) at 4 ≤ z ≤ 8. We assumed that the [CII]-line emission originates from photo-dominated regions. At such high redshift, the CMB represents a strong background and we discuss its effects on the luminosity of the [CII] line. We studied the L[CII ]-SFR and L[ CII ]-Zg relations and show that they do not strongly evolve with redshift from z = 4 and to z = 8. Galaxies with higher [CII] luminosities tend to have higher metallicities and higher SFRs but the correlations are very broad, with a scatter of about 0.5 and 0.8 dex for L[ CII ]-SFR and L[ CII ]-Zg, respectively. Our model reproduces the L[ CII ]-SFR relations observed in high-redshift star-forming galaxies, with [CII] luminosities lower than expected from local L[ CII ]-SFR relations. Accordingly, the local observed L[ CII ]-SFR relation does not apply at high-z (z ≳ 5), even when CMB effects are ignored. Our model naturally produces the [CII] deficit (i.e. the decrease of L[ CII ]/LIR with LIR), which appears to be strongly correlated with the intensity of the radiation field in our simulated galaxies. We then predict the

  17. Dynamical dark energy simulations: high accuracy power spectra at high redshift

    Energy Technology Data Exchange (ETDEWEB)

    Casarini, Luciano; Bonometto, Silvio A. [Department of Physics G. Occhialini-Milano-Bicocca University, Piazza della Scienza 3, 20126 Milano (Italy); Maccio, Andrea V., E-mail: luciano.casarini@mib.infn.it, E-mail: maccio@mpia.de, E-mail: silvio.bonometto@mib.infn.it [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany)

    2009-03-15

    Accurate predictions on non-linear power spectra, at various redshift z, will be a basic tool to interpret cosmological data from next generation mass probes, so obtaining key information on Dark Energy nature. This calls for high precision simulations, covering the whole functional space of w(z) state equations and taking also into account the admitted ranges of other cosmological parameters; surely a difficult task. A procedure was however suggested, able to match the spectra at z = 0, up to k {approx} 3 hMpc{sup -1}, in cosmologies with an (almost) arbitrary w(z), by making recourse to the results of N-body simulations with w = const. In this paper we extend such procedure to high redshift and test our approach through a series of N-body gravitational simulations of various models, including a model closely fitting WMAP5 and complementary data. Our approach detects w = const. models, whose spectra meet the requirement within 1% at z = 0 and perform even better at higher redshift, where they are close to a permil precision. Available Halofit expressions, extended to (constant) w{ne}-1 are unfortunately unsuitable to fit the spectra of the physical models considered here. Their extension to cover the desired range should be however feasible, and this will enable us to match spectra from any DE state equation.

  18. Spectroscopic confirmation of high-redshift supernovae with the ESO VLT

    Energy Technology Data Exchange (ETDEWEB)

    Lidman, C.; Howell, D.A.; Folatelli, G.; Garavini, G.; Nobili, S.; Aldering, G.; Amanullah, R.; Antilogus, P.; Astier, P.; Blanc, G.; Burns, M.S.; Conley, A.; Deustua, S.E.; Doi, M.; Ellis, R.; Fabbro, S.; Fadeyev, V.; Gibbons, R.; Goldhaber, G.; Goobar, A.; Groom, D.E.; Hook, I.; Kashikawa, N.; Kim, A.G.; Knop, R.A.; Lee, B.C.; Mendez, J.; Morokuma, T.; Motohara, K.; Nugent, P.E.; Pain, R.; Perlmutter, S.; Prasad, V.; Quimby, R.; Raux, J.; Regnault, N.; Ruiz-Lapuente, P.; Sainton, G.; Schaefer, B.E.; Schahmaneche, K.; Smith, E.; Spadafora, A.L.; Stanishev, V.; Walton, N.A.; Wang, L.; Wood-Vasey, W.M.; Yasuda,

    2004-10-04

    We present VLT FORS1 and FORS2 spectra of 39 candidate high-redshift supernovae that were discovered as part of a cosmological study using type Ia supernovae (SNe Ia) over a wide range of redshifts. From the spectra alone, 20 candidates are spectrally classified as SNe Ia with redshifts ranging from z = 0.212 to z = 1.181. Of the remaining 19 candidates, 1 might be a type II supernova and 11 exhibit broad supernova-like spectral features and/or have supernova-like light curves. The candidates were discovered in 8 separate ground-based searches. In those searches in which SNe Ia at z {approx} 0.5 were targeted, over 80 percent of the observed candidates were spectrally classified as SNe Ia. In those searches in which SNe Ia with z > 1 were targeted, 4 candidates with z > 1 were spectrally classified as SNe Ia and later followed with ground and space based observatories. We present the spectra of all candidates, including those that could not be spectrally classified as supernova.

  19. Local analogues of high-redshift star-forming galaxies: integral field spectroscopy of green peas

    Science.gov (United States)

    Lofthouse, E. K.; Houghton, R. C. W.; Kaviraj, S.

    2017-10-01

    We use integral field spectroscopy, from the SWIFT and PALM3K instruments, to perform a spatially resolved spectroscopic analysis of four nearby highly star-forming 'green pea' (GP) galaxies, that are likely analogues of high-redshift star-forming systems. By studying emission-line maps in H α, [N II] λλ6548,6584 and [S II] λλ6716,6731, we explore the kinematic morphology of these systems and constrain properties such as gas-phase metallicities, electron densities and gas-ionization mechanisms. Two of our GPs are rotationally supported while the others are dispersion-dominated systems. The rotationally supported galaxies both show evidence for recent or ongoing mergers. However, given that these systems have intact discs, these interactions are likely to have low-mass ratios (I.e. minor mergers), suggesting that the minor-merger process may be partly responsible for the high star formation rates seen in these GPs. Nevertheless, the fact that the other two GPs appear morphologically undisturbed suggests that mergers (including minor mergers) are not necessary for driving the high star formation rates in such galaxies. We show that the GPs are metal-poor systems (25-40 per cent of solar) and that the gas ionization is not driven by active galactic nuclei (AGN) in any of our systems, indicating that the AGN activity is not coeval with star formation in these starbursting galaxies.

  20. A new method to obtain the broad line region size of high redshift quasars

    Energy Technology Data Exchange (ETDEWEB)

    Negrete, C. Alenka [Instituto Nacional de Astrofísica, Óptica y Electrónica (Mexico); Dultzin, Deborah [Instituto de Astronomía, Universidad Nacional Autónoma de México (Mexico); Marziani, Paola [INAF, Astronomical Observatory of Padova (Italy); Sulentic, Jack W., E-mail: cnegrete@inaoep.mx, E-mail: deborah@astro.unam.mx, E-mail: paola.marziani@oapd.inaf.it, E-mail: sulentic@iaa.es [Instituto de Astrofísica de Andalucía (Spain)

    2014-10-10

    We present high signal-to-noise ratio UV spectra for eight quasars at z ∼ 3 obtained with Very Large Telescope/FORS. The spectra enable us to analyze in detail the strong and weak emission features in the rest frame range 1300-2000 Å of each source (C III] λ1909, Si III] λ1892, Al III λ1860, Si II λ1814, C IV λ1549 and blended Si IV λ1397+O IV] λ1402). The flux ratios Al III λ1860/Si III] λ1892, C IV λ1549/Al III λ1860, Si IV λ1397+O IV] λ1402/Si III] λ1892 and Si IV λ1397+O IV] λ1402/C IV λ1549 strongly constrain ionizing photon flux and metallicity through the use of diagnostic maps built from CLOUDY simulations. The radius of the broad line region is then derived from the ionizing photon flux applying the definition of the ionization parameter. The r {sub BLR} estimate and the width of a virial component isolated in prominent UV lines yields an estimate of black hole mass. We compare our results with previous estimates obtained from the r {sub BLR}-luminosity correlation customarily employed to estimate the black hole masses of high redshift quasars.

  1. Can planet formation resolve the dust budget crisis in high-redshift galaxies?

    Science.gov (United States)

    Forgan, D. H.; Rowlands, K.; Gomez, H. L.; Gomez, E. L.; Schofield, S. P.; Dunne, L.; Maddox, S.

    2017-12-01

    The process of planet formation offers a rich source of dust production via grain growth in protostellar discs, and via grinding of larger bodies in debris disc systems. Chemical evolution models, designed to follow the build up of metals and dust in galaxies, do not currently account for planet formation. We consider the possibility that the apparent underprediction of dust mass in high-redshift galaxies by chemical evolution models could be in part, due to these models neglecting this process, specifically due to their assumption that a large fraction of the dust mass is removed from the interstellar medium during star formation (so-called astration). By adding a planet formation phase into galaxy chemical evolution, we demonstrate that the dust budget crisis can be partially ameliorated by a factor of 1.3-1.5 only if (I) circumstellar discs prevent a large fraction of the dust mass entering the star during its birth, and (II) that dust mass is preferentially liberated via jets, winds and outflows rather than accreted into planetary-mass bodies.

  2. The impact of coupled dark energy cosmologies on the high-redshift intergalactic medium

    Science.gov (United States)

    Baldi, M.; Viel, M.

    2010-11-01

    We present an analysis of high-resolution hydrodynamical N-body simulations of coupled dark energy cosmologies which focuses on the statistical properties of the transmitted Lyman α flux in the high-redshift intergalactic medium (IGM). In these models the growth of the diffuse cosmic web differs from the standard ΛCDM case: the density distribution is skewed towards underdense regions and the matter power spectra are typically larger (in a scale-dependent way). These differences are also appreciable in the Lyman α flux and are larger than 5 per cent (10 per cent) at z = 2-4 in the flux probability distribution function (pdf) for high-transmissivity regions and for values of the coupling parameter β = 0.08 (β = 0.2). The flux power spectrum is also affected at the ~2 per cent (~5-10 per cent) level for β = 0.08 (β = 0.2) in a redshift-dependent way. We infer the behaviour of flux pdf and flux power for a reasonable range of couplings and present constraints using present high- and low-resolution data sets. We find an upper limit β <~ 0.15 (at 2σ confidence level), which is obtained using only IGM data and is competitive with those inferred from other large-scale structure probes.

  3. Mass and metallicity scaling relations of high-redshift star-forming galaxies selected by GRBs

    Science.gov (United States)

    Arabsalmani, M.; Møller, P.; Perley, D. A.; Freudling, W.; Fynbo, J. P. U.; Le Floc'h, E.; Zwaan, M. A.; Schulze, S.; Tanvir, N. R.; Christensen, L.; Levan, A. J.; Jakobsson, P.; Malesani, D.; Cano, Z.; Covino, S.; D'Elia, V.; Goldoni, P.; Gomboc, A.; Heintz, K. E.; Sparre, M.; de Ugarte Postigo, A.; Vergani, S. D.

    2018-01-01

    We present a comprehensive study of the relations between gas kinematics, metallicity and stellar mass in a sample of 82 gamma-ray burst (GRB)-selected galaxies using absorption and emission methods. We find the velocity widths of both emission and absorption profiles to be a proxy of stellar mass. We also investigate the velocity-metallicity correlation and its evolution with redshift. Using 33 GRB hosts with measured stellar mass and metallicity, we study the mass-metallicity relation for GRB host galaxies in a stellar mass range of 108.2-1011.1 M⊙ and a redshift range of z ∼ 0.3-3.4. The GRB-selected galaxies appear to track the mass-metallicity relation of star-forming galaxies but with an offset of 0.15 towards lower metallicities. This offset is comparable with the average error bar on the metallicity measurements of the GRB sample and also the scatter on the mass-metallicity relation of the general population. It is hard to decide whether this relatively small offset is due to systematic effects or the intrinsic nature of GRB hosts. We also investigate the possibility of using absorption-line metallicity measurements of GRB hosts to study the mass-metallicity relation at high redshifts. Our analysis shows that the metallicity measurements from absorption methods can significantly differ from emission metallicities and assuming identical measurements from the two methods may result in erroneous conclusions.

  4. Herschel And Alma Observations Of The Ism In Massive High-Redshift Galaxy Clusters

    Science.gov (United States)

    Wu, John F.; Aguirre, Paula; Baker, Andrew J.; Devlin, Mark J.; Hilton, Matt; Hughes, John P.; Infante, Leopoldo; Lindner, Robert R.; Sifón, Cristóbal

    2017-06-01

    The Sunyaev-Zel'dovich effect (SZE) can be used to select samples of galaxy clusters that are essentially mass-limited out to arbitrarily high redshifts. I will present results from an investigation of the star formation properties of galaxies in four massive clusters, extending to z 1, which were selected on the basis of their SZE decrements in the Atacama Cosmology Telescope (ACT) survey. All four clusters have been imaged with Herschel/PACS (tracing star formation rate) and two with ALMA (tracing dust and cold gas mass); newly discovered ALMA CO(4-3) and [CI] line detections expand an already large sample of spectroscopically confirmed cluster members. Star formation rate appears to anti-correlate with environmental density, but this trend vanishes after controlling for stellar mass. Elevated star formation and higher CO excitation are seen in "El Gordo," a violent cluster merger, relative to a virialized cluster at a similar high (z 1) redshift. Also exploiting ATCA 2.1 GHz observations to identify radio-loud active galactic nuclei (AGN) in our sample, I will use these data to develop a coherent picture of how environment influences galaxies' ISM properties and evolution in the most massive clusters at early cosmic times.

  5. DUST FORMATION, EVOLUTION, AND OBSCURATION EFFECTS IN THE VERY HIGH-REDSHIFT UNIVERSE

    Energy Technology Data Exchange (ETDEWEB)

    Dwek, Eli; Benford, Dominic J. [Observational Cosmology Lab., Code 665, NASA at Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Staguhn, Johannes; Su, Ting [Also at Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA. (United States); Arendt, Richard G. [Also at CRESST, University of Maryland Baltimore County, Baltimore, MD 21250, USA. (United States); Kovacks, Attila, E-mail: eli.dwek@nasa.gov [Also at Astronomy Department, CalTech, Pasadena, CA 90025, USA. (United States)

    2014-06-20

    The evolution of dust at redshifts z ≳ 9, and consequently the dust properties, differs greatly from that in the local universe. In contrast to the local universe, core collapse supernovae (CCSNe) are the only source of thermally condensed dust. Because of the low initial dust-to-gas mass ratio, grain destruction rates are low, so that CCSNe are net producers of interstellar dust. Galaxies with large initial gas mass or high mass infall rate will therefore have a more rapid net rate of dust production compared to galaxies with lower gas mass, even at the same star formation rate. The dust composition is dominated by silicates, which exhibit a strong rise in the UV opacity near the Lyman break. This ''silicate-UV break'' may be confused with the Lyman break, resulting in a misidentification of a galaxy's photometric redshift. In this Letter we demonstrate these effects by analyzing the spectral energy distribution of MACS1149-JD, a lensed galaxy at z = 9.6. A potential 2 mm counterpart of MACS1149-JD has been identified with GISMO. While additional observations are required to corroborate this identification, we use this possible association to illustrate the physical processes and the observational effects of dust in the very high-redshift universe.

  6. The discovery of high-redshift supernovae and their cosmological implications

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Alex G. [Univ. of California, Berkeley, CA (United States). Dept. of Physics

    1997-09-01

    In this thesis the author discusses the methodology for doing photometry from procedure of extracting supernova counts from images that contain combined supernova plus galaxy flux, to standard star calibration, to additional instrumental corrections that arise due to the multiple telescopes used for observations. He discusses the different sources of photometric error and their correlations, and the construction of the covariance matrix for all the points in the light curve. He then describes the K corrections which account for the redshifting of spectra that are necessary to compare the photometry of the high-redshift data with those from nearby (z < 0.1) supernovae. Finally, he uses the first seven of the supernovae to test the hypothesis that they live in an under-dense bubble where the locally measured Hubble constant differs significantly from the true Hubble constant. He also uses the data to place limits on the value of the Hubble constant. Discussions of several other important aspects of the data analysis are or will be included in other papers. These topics include a description of how the covariance matrix is used to generate light-curve fits, a discussion of non-photometric systematic errors that also effect the measurements, and a discussion of the application of the supernovae to address other scientific/cosmological problems.

  7. The XMM-Newton Very Large Program on Cosmology with High-Redshift Quasars

    Science.gov (United States)

    Risaliti, G.

    2017-10-01

    The non-linear relation between the X-ray and UV emission in quasars can be used to estimate the distance of quasars with a precision of 0.2 dex. Based on this property, we built a Hubble Diagram of quasars up to z˜6. This provides a new way to test the cosmological model at high redshift, and to measure the cosmological parameters. So far, we filled the Hubble Diagram with SDSS quasars with serendipitous XMM observation. This is an efficient method up to z˜2-2.5, but at higher redshifts pointed observations are needed in order to constrain the cosmological models. XMM-Newton will observe 30 optically bright quasars at z 3, allowing to measure the expansion rate of the Universe at z=3 with a 8% precision. This will provide a tight test of the standard LCDM model, and an improvement of the constraints on the possible evolution of the equation of state of the dark energy.

  8. THE COMPLEX PHYSICS OF DUSTY STAR-FORMING GALAXIES AT HIGH REDSHIFTS AS REVEALED BY HERSCHEL AND SPITZER

    Energy Technology Data Exchange (ETDEWEB)

    Lo Faro, B.; Franceschini, A.; Vaccari, M.; Rodighiero, G.; Feltre, A.; Marchetti, L. [Dipartimento di Fisica e Astronomia, Universita di Padova, vicolo Osservatorio, 3, I-35122 Padova (Italy); Silva, L. [INAF-OATs, Via Tiepolo 11, I-34131 Trieste (Italy); Berta, S.; Lutz, D.; Magnelli, B. [MPE, Postfach 1312, D-85741, Garching (Germany); Bock, J. [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Burgarella, D.; Buat, V. [Laboratoire d' Astrophysique de Marseille, OAMP, Universite Aix-Marseille, CNRS, 38 rue Frederic Joliot-Curie, F-13388 Marseille Cedex 13 (France); Cava, A. [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Clements, D. L. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Farrah, D.; Hurley, P. [Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Solares, E. A. Gonzalez [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Magdis, G., E-mail: barbara.lofaro@studenti.unipd.it [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); and others

    2013-01-10

    We combine far-infrared photometry from Herschel (PEP/HerMES) with deep mid-infrared spectroscopy from Spitzer to investigate the nature and the mass assembly history of a sample of 31 luminous and ultraluminous infrared galaxies ((U)LIRGs) at z {approx} 1 and 2 selected in GOODS-S with 24 {mu}m fluxes between 0.2 and 0.5 mJy. We model the data with a self-consistent physical model (GRASIL) which includes a state-of-the-art treatment of dust extinction and reprocessing. We find that all of our galaxies appear to require massive populations of old (>1 Gyr) stars and, at the same time, to host a moderate ongoing activity of star formation (SFR {<=} 100 M {sub Sun} yr{sup -1}). The bulk of the stars appear to have been formed a few Gyr before the observation in essentially all cases. Only five galaxies of the sample require a recent starburst superimposed on a quiescent star formation history. We also find discrepancies between our results and those based on optical-only spectral energy distribution (SED) fitting for the same objects; by fitting their observed SEDs with our physical model we find higher extinctions (by {Delta}A {sub V} {approx} 0.81 and 1.14) and higher stellar masses (by {Delta}log(M {sub *}) {approx} 0.16 and 0.36 dex) for z {approx} 1 and z {approx} 2 (U)LIRGs, respectively. The stellar mass difference is larger for the most dust-obscured objects. We also find lower SFRs than those computed from L {sub IR} using the Kennicutt relation due to the significant contribution to the dust heating by intermediate-age stellar populations through 'cirrus' emission ({approx}73% and {approx}66% of the total L {sub IR} for z {approx} 1 and z {approx} 2 (U)LIRGs, respectively).

  9. First light: exploring the spectra of high-redshift galaxies in the Renaissance Simulations

    Science.gov (United States)

    Barrow, Kirk S. S.; Wise, John H.; Norman, Michael L.; O'Shea, Brian W.; Xu, Hao

    2017-08-01

    We present synthetic observations for the first generations of galaxies in the Universe and make predictions for future deep field observations for redshifts greater than 6. Due to the strong impact of nebular emission lines and the relatively compact scale of H II regions, high-resolution cosmological simulations and a robust suite of analysis tools are required to properly simulate spectra. We created a software pipeline consisting of fsps, hyperion, cloudy and our own tools to generate synthetic IR observations from a fully three-dimensional arrangement of gas, dust, and stars. Our prescription allows us to include emission lines for a complete chemical network and tackle the effect of dust extinction and scattering in the various lines of sight. We provide spectra, 2D binned photon imagery for both HST and JWST IR filters, luminosity relationships, and emission-line strengths for a large sample of high-redshift galaxies in the Renaissance Simulations. Our resulting synthetic spectra show high variability between galactic haloes with a strong dependence on stellar mass, metallicity, gas mass fraction, and formation history. Haloes with the lowest stellar mass have the greatest variability in [O III]/Hβ, [O III], and C III], while haloes with higher masses are seen to show consistency in their spectra and [O III] equivalent widths between 1 and 10 Å. Viewing angle accounted for threefold difference in flux due to the presence of ionized gas channels in a halo. Furthermore, JWST colour plots show a discernible relationship between redshift, colour, and mean stellar age.

  10. Probing Primordial Magnetic Fields with 21-cm Line Observations of the High-redshift Intergalactic Medium

    Science.gov (United States)

    Oklopcic, Antonija; Gluscevic, V.; Hirata, C. M.; Mishra, A.; Venumadhav, T. N.

    2014-01-01

    Coherent magnetic fields with strengths of the order of 10^(-5) G are observed on scales of individual galaxies, including the Milky Way. They are thought to be organized and maintained by a dynamo mechanism. However, the nature and origin of the seed magnetic field, required for the dynamo effect to take place, are still unknown. Here, we propose a method of probing the magnetic field in the intergalactic medium before the Epoch of Reionization through observations of redshifted 21-cm radiation of neutral hydrogen. The 21-cm line is created during the spin-flip transition between the hyperfine levels of the hydrogen ground state. The upper hyperfine level is a triplet consisting of atomic states with three different projections of the total angular momentum vector. Anisotropic 21-cm radiation, resulting from perturbations in the high-redshift IGM, unevenly populates triplet sublevels. If an atom is located in an external magnetic field, it precesses between the three states; this causes an additional anisotropy in the 21-cm radiation, which could be imprinted in the 21-cm power spectrum. In order to evaluate the effect of the magnetic field, we need to consider in full detail all mechanisms that affect the distribution of atoms in hyperfine sublevels, such as the interaction of hydrogen atoms with the 21-cm radiation, optical pumping by Lyman-alpha photons, and spin-exchange in hydrogen-hydrogen collisions. Preliminary calculations suggest that this method could be sensitive to extremely weak magnetic fields, of the order of 10^(-17) G.

  11. Lyα excess in high-redshift radio galaxies: a signature of star formation

    Science.gov (United States)

    Villar-Martín, M.; Humphrey, A.; De Breuck, C.; Fosbury, R.; Binette, L.; Vernet, J.

    2007-03-01

    About 54 per cent of radio galaxies at z >= 3 and 8 per cent of radio galaxies at 2 ~ 2) radio galaxies. These Lyα-excess objects (LAEs) show Lyα/HeII values consistent with or above standard photoionization model predictions. We reject with confidence several scenarios to explain the unusual strength of Lyα in these objects: shocks, low nebular metallicities, high gas densities and absorption/scattering effects. We show that the most successful explanation is the presence of a young stellar population which provides the extra supply of ionizing photons required to explain the Lyα excess in at least the most extreme LAEs (probably in all of them). This interpretation is strongly supported by the tentative trend found by other authors for z >= 3 radio galaxies to show lower ultraviolet rest-frame polarization levels, or the dramatic increase in the detection rate at submm wavelengths of z > 2.5 radio galaxies. The enhanced star formation activity in LAEs could be a consequence of a recent merger which has triggered both the star formation and the active galactic nucleus/radio activities. The measurement of unusually high Lyα ratios in the extended gas of some high-redshift radio galaxies suggests that star formation activity occurs in spatial scales of tens of kpc. We argue that, although the fraction of LAEs may be incompletely determined, both at 2 = 3, the much larger fraction of LAEs found at z >= 3 is a genuine redshift evolution and not due to selection effects. Therefore, our results suggest that the radio galaxy phenomenon is more often associated with a massive starburst at z > 3 than at z < 3. Unpublished results are presented in this paper for the radio galaxy 1338-1941, based on observations carried out at the European Southern Observatory, Paranal (Chile) for the ESO project 69.B-0078(B). E-mail: montse@iaa.es

  12. From nearby low-mass protostars to high redshift starbursts: protostellar outflows tracing the IMF

    Science.gov (United States)

    Kristensen, Lars E.; Bergin, Edwin

    2015-08-01

    Embedded low-mass protostars are notoriously difficult to observe even in the nearest Galactic high-mass clusters where they outnumber the high-mass protostars by orders of magnitude. Thus, without a good tracer of the low-mass population, we do not have a good handle on the shape of the initial (core) mass function, leaving little hope for extrapolating to extragalactic regions where we will never have neither the sensitivity nor the resolution to directly observe this population. A good tracer of the low-mass population is needed.One such physical tracer is outflows. Outflow emission is directly proportional to envelope mass, and outflows are predominantly active during the deeply embedded phases of star formation. What is required for this method to work is species and transitions tracing outflows uniquely such that any signal is not diluted by the surrounding cloud, such as certain methanol transitions, water, high-J CO (J > 10).I will present a statistical model of a forming high-mass cluster. The model includes what we currently know about Galactic high-mass clusters and incorporates outflow emission from low-mass protostars. The latter component is obtained from observations of tens of nearby embedded low-mass protostellar outflows in the above-mentioned tracers. The model is benchmarked against ALMA and Herschel-HIFI observations of Galactic clusters proving the concept, and preliminary extrapolations to the extragalactic regime are presented. With this new probe, and traditional probes of the distant star formation which predominantly trace high mass stars, we will be able to explore the IMF in starburst galaxies from low to high redshift.

  13. Gas clump formation via thermal instability in high-redshift dwarf galaxy mergers

    Science.gov (United States)

    Arata, Shohei; Yajima, Hidenobu; Nagamine, Kentaro

    2018-01-01

    Star formation in high-redshift dwarf galaxies is a key to understand early galaxy evolution in the early Universe. Using the three-dimensional hydrodynamics code GIZMO, we study the formation mechanism of cold, high-density gas clouds in interacting dwarf galaxies with halo masses of ˜3 × 107 M⊙, which are likely to be the formation sites of early star clusters. Our simulations can resolve both the structure of interstellar medium on small scales of ≲ 0.1 pc and the galactic disk simultaneously. We find that the cold gas clouds form in the post-shock region via thermal instability due to metal-line cooling, when the cooling time is shorter than the galactic dynamical time. The mass function of cold clouds shows almost a power-law initially with an upper limit of thermally unstable scale. We find that some clouds merge into more massive ones with ≳ 104 M⊙ within ˜ 2 Myr. Only the massive cold clouds with ≳ 103 M⊙ can keep collapsing due to gravitational instability, resulting in the formation of star clusters. We find that the clump formation is more efficient in the prograde-prograde merger than the prograde-retrograde case due to the difference in the degree of shear flow. In addition, we investigate the dependence of cloud mass function on metallicity and {H2} abundance, and show that the cases with low metallicities (≲ 10-2 Z⊙) or high {H2} abundance (≳ 10-3) cannot form massive cold clouds with ≳ 103 M⊙.

  14. Low Masses and High Redshifts: The Evolution of the Mass-Metallicity Relation

    Science.gov (United States)

    Henry, Alaina; Scarlata, Claudia; Dominguez, Alberto; Malkan, Matthew; Martin, Crystal L.; Siana, Brian; Atek, Hakim; Bedregal, Alejandro G.; Colbert, James W.; Rafelski, Marc; hide

    2013-01-01

    We present the first robust measurement of the high redshift mass-metallicity (MZ) relation at 10(exp 8) grism spectroscopy with the Hubble Space Telescope Wide Field Camera 3 is sensitive to the R23 metallicity diagnostic: ([O II] (lambda)(lambda)3726, 3729 + [OIII] (lambda)(lambda)4959, 5007)/H(beta). Using spectra stacked in four mass quartiles, we find a MZ relation that declines significantly with decreasing mass, extending from 12+log(O/H) = 8.8 at M = 10(exp 9.8) Stellar Mass to 12+log(O/H)= 8.2 at M = 10(exp 8.2) Stellar Mass. After correcting for systematic offsets between metallicity indicators, we compare our MZ relation to measurements from the stacked spectra of galaxies with M > or approx. 10(exp 9.5) Stellar Mass and z approx. 2.3. Within the statistical uncertainties, our MZ relation agrees with the z approx. 2.3 result, particularly since our somewhat higher metallicities (by around 0.1 dex) are qualitatively consistent with the lower mean redshift (z = 1.76) of our sample. For the masses probed by our data, the MZ relation shows a steep slope which is suggestive of feedback from energy-driven winds, and a cosmological downsizing evolution where high mass galaxies reach the local MZ relation at earlier times. In addition, we show that our sample falls on an extrapolation of the star-forming main sequence (the SFR-M* relation) at this redshift. This result indicates that grism emission-line selected samples do not have preferentially high star formation rates (SFRs). Finally, we report no evidence for evolution of the mass-metallicity-SFR plane; our stack-averaged measurements show excellent agreement with the local relation.

  15. Jetted tidal disruptions of stars as a flag of intermediate mass black holes at high redshifts

    Science.gov (United States)

    Fialkov, Anastasia; Loeb, Abraham

    2017-11-01

    Tidal disruption events (TDEs) of stars by single or binary supermassive black holes (SMBHs) brighten galactic nuclei and reveal a population of otherwise dormant black holes. Adopting event rates from the literature, we aim to establish general trends in the redshift evolution of the TDE number counts and their observable signals. We pay particular attention to (I) jetted TDEs whose luminosity is boosted by relativistic beaming and (II) TDEs around binary black holes. We show that the brightest (jetted) TDEs are expected to be produced by massive black hole binaries if the occupancy of intermediate mass black holes (IMBHs) in low-mass galaxies is high. The same binary population will also provide gravitational wave sources for the evolved Laser Interferometer Space Antenna. In addition, we find that the shape of the X-ray luminosity function of TDEs strongly depends on the occupancy of IMBHs and could be used to constrain scenarios of SMBH formation. Finally, we make predictions for the expected number of TDEs observed by future X-ray telescopes finding that a 50 times more sensitive instrument than the Burst Alert Telescope (BAT) on board the Swift satellite is expected to trigger ˜10 times more events than BAT, while 6-20 TDEs are expected in each deep field observed by a telescope 50 times more sensitive than the Chandra X-ray Observatory if the occupation fraction of IMBHs is high. Because of their long decay times, high-redshift TDEs can be mistaken for fixed point sources in deep field surveys and targeted observations of the same deep field with year-long intervals could reveal TDEs.

  16. Exploring the Chemical Link Between Local Ellipticals and Their High-Redshift Progenitors

    Science.gov (United States)

    Leja, Joel; Van Dokkum, Pieter G.; Momcheva, Ivelina; Brammer, Gabriel; Skelton, Rosalind E.; Whitaker, Katherine E.; Andrews, Brett H.; Franx, Marijn; Kriek, Mariska; Van Der Wel, Arjen; hide

    2013-01-01

    We present Keck/MOSFIRE K-band spectroscopy of the first mass-selected sample of galaxies at z approximately 2.3. Targets are selected from the 3D-Hubble Space Telescope Treasury survey. The six detected galaxies have a mean [N II]lambda6584/H-alpha ratio of 0.27 +/- 0.01, with a small standard deviation of 0.05. This mean value is similar to that of UV-selected galaxies of the same mass. The mean gas-phase oxygen abundance inferred from the [N II]/Halpha ratios depends on the calibration method, and ranges from 12+log(O/H)(sub gas) = 8.57 for the Pettini & Pagel calibration to 12+log(O/H)(sub gas) = 8.87 for the Maiolino et al. calibration. Measurements of the stellar oxygen abundance in nearby quiescent galaxies with the same number density indicate 12+log(O/H)(sub stars) = 8.95, similar to the gas-phase abundances of the z approximately 2.3 galaxies if the Maiolino et al. calibration is used. This suggests that these high-redshift star forming galaxies may be progenitors of today's massive early-type galaxies. The main uncertainties are the absolute calibration of the gas-phase oxygen abundance and the incompleteness of the z approximately 2.3 sample: the galaxies with detected Ha tend to be larger and have higher star formation rates than the galaxies without detected H-alpha, and we may still be missing the most dust-obscured progenitors.

  17. Discovery of the near-infrared counterpart to the luminous neutron-star low-mass X-ray binary GX 3+1

    Energy Technology Data Exchange (ETDEWEB)

    Van den Berg, Maureen; Fridriksson, Joel K. [Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Homan, Jeroen [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 70 Vassar Street, Cambridge, MA 02139 (United States); Linares, Manuel, E-mail: M.C.vandenBerg@uva.nl [Instituto de Astrofísica de Canarias (IAC), Vía Láctea s/n, La Laguna, E-38205, S/C de Tenerife (Spain)

    2014-10-01

    Using the High Resolution Camera on board the Chandra X-ray Observatory, we have measured an accurate position for the bright persistent neutron star X-ray binary and atoll source GX 3+1. At a location that is consistent with this new position, we have discovered the near-infrared (NIR) counterpart to GX 3+1 in images taken with the PANIC and FourStar cameras on the Magellan Baade Telescope. The identification of this K{sub s} = 15.8 ± 0.1 mag star as the counterpart is based on the presence of a Br γ emission line in an NIR spectrum taken with the Folded-port InfraRed Echelette spectrograph on the Baade Telescope. The absolute magnitude derived from the best available distance estimate to GX 3+1 indicates that the mass donor in the system is not a late-type giant. We find that the NIR light in GX 3+1 is likely dominated by the contribution from a heated outer accretion disk. This is similar to what has been found for the NIR flux from the brighter class of Z sources, but unlike the behavior of atolls fainter (L{sub X} ≈ 10{sup 36}-10{sup 37} erg s{sup –1}) than GX 3+1, where optically thin synchrotron emission from a jet probably dominates the NIR flux.

  18. The Impact of Foregrounds on Redshift Space Distortion Measurements With the Highly-Redshifted 21 cm Line

    OpenAIRE

    Pober, Jonathan C.

    2014-01-01

    The highly redshifted 21 cm line of neutral hydrogen has become recognized as a unique probe of cosmology from relatively low redshifts (z ~ 1) up through the Epoch of Reionization (z ~ 8) and even beyond. To date, most work has focused on recovering the spherically averaged power spectrum of the 21 cm signal, since this approach maximizes the signal-to-noise in the initial measurement. However, like galaxy surveys, the 21 cm signal is affected by redshift space distortions, and is inherently...

  19. The Cycle of Dust in the Milky Ways: Clues from the High-Redshift and the Local Universe

    Science.gov (United States)

    Dwek, Eli

    2008-01-01

    Massive amount of dust has been observed at high-redshifts when the universe was a mere 900 Myr old. The formation and evolution of dust is there dominated by massive stars and interstellar processes. In contrast, in the local universe lower mass stars, predominantly 2-5 Msun AGB stars, play the dominant role in the production of interstellar dust. These two extreme environments offer fascinating clues about the evolution of dust in the Milky Way galaxy

  20. PROBING HIGH-REDSHIFT GALAXY FORMATION AT THE HIGHEST LUMINOSITIES: NEW INSIGHTS FROM DEIMOS SPECTROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyoung-Soo [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States); Dey, Arjun [National Optical Astronomy Observatory, Tucson, AZ 85726 (United States); Cooper, Michael C. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Reddy, Naveen [Department of Physics and Astronomy, University of California, Riverside, 900 University Avenue, Riverside, CA 92521 (United States); Jannuzi, Buell T. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

    2013-07-01

    We present Keck DEIMOS spectroscopic observations of the most UV-luminous star-forming galaxies at redshifts 3.2 < z < 4.6. Our sample, selected in the Booetes field of the NOAO Deep Wide-Field Survey, contains galaxies with luminosities of L* {approx}< L{sub UV} {approx}< 7 L* and is one of the largest samples to date of the most UV-luminous galaxies at these redshifts. Our spectroscopic data confirm 41 candidates as star-forming galaxies at 3.2 < z < 4.6 and validate the relatively clean selection of the photometric candidates with a contamination rate of 11%-28%. We find that the fraction of Ly{alpha} emitting galaxies increases with decreasing UV luminosity. None of the 12 galaxies with M{sub UV} < -22 (i.e., L{sub UV} > 3 L*) exhibit strong Ly{alpha} emission. We find strong evidence of large-scale outflows, transporting the neutral/ionized gas in the interstellar medium away from the galaxy. Galaxies exhibiting both interstellar absorption and Ly{alpha} emission lines show a significant offset between the two features, with a relative velocity of 200-1150 km s{sup -1}. We find tentative evidence that this measure of the outflow velocity increases with UV luminosity and/or stellar mass. The luminosity- and mass-dependent outflow strengths suggest that the efficiency of feedback and enrichment of the surrounding medium depend on these galaxy parameters. We also stack the individual spectra to construct composite spectra of the absorption-line-only and Ly{alpha}-emitting subsets of the UV luminous galaxies at z {approx_equal} 3.7. The composite spectra are very similar to those of lower-redshift and lower-luminosity Lyman break galaxy (LBG) samples, but with some subtle differences. Analyses of the composite spectra suggest that the UV luminous LBGs at z {approx_equal} 3.7 may have a higher covering fraction of absorbing gas, and may be older (or have had more prolonged star formation histories) than their lower-redshift and lower-luminosity counterparts. In

  1. GALAXY EVOLUTION AT HIGH REDSHIFT: OBSCURED STAR FORMATION, GRB RATES, COSMIC REIONIZATION, AND MISSING SATELLITES

    Energy Technology Data Exchange (ETDEWEB)

    Lapi, A.; Mancuso, C.; Celotti, A.; Danese, L. [SISSA, Via Bonomea 265, I-34136 Trieste (Italy)

    2017-01-20

    We provide a holistic view of galaxy evolution at high redshifts z ≳ 4, which incorporates the constraints from various astrophysical/cosmological probes, including the estimate of the cosmic star formation rate (SFR) density from UV/IR surveys and long gamma-ray burst (GRBs) rates, the cosmic reionization history following the latest Planck measurements, and the missing satellites issue. We achieve this goal in a model-independent way by exploiting the SFR functions derived by Mancuso et al. on the basis of an educated extrapolation of the latest UV/far-IR data from HST / Herschel , and already tested against a number of independent observables. Our SFR functions integrated down to a UV magnitude limit M {sub UV} ≲ −13 (or SFR limit around 10{sup −2} M {sub ⊙} yr{sup −1}) produce a cosmic SFR density in excellent agreement with recent determinations from IR surveys and, taking into account a metallicity ceiling Z ≲ Z {sub ⊙}/2, with the estimates from long GRB rates. They also yield a cosmic reionization history consistent with that implied by the recent measurements of the Planck mission of the electron scattering optical depth τ {sub es} ≈ 0.058; remarkably, this result is obtained under a conceivable assumption regarding the average value f {sub esc} ≈ 0.1 of the escape fraction for ionizing photons. We demonstrate via the abundance-matching technique that the above constraints concurrently imply galaxy formation becoming inefficient within dark matter halos of mass below a few 10{sup 8} M {sub ⊙}; pleasingly, such a limit is also required so as not to run into the missing satellites issue. Finally, we predict a downturn of the Galaxy luminosity function faintward of M {sub UV} ≲ −12, and stress that its detailed shape, to be plausibly probed in the near future by the JWST , will be extremely informative on the astrophysics of galaxy formation in small halos, or even on the microscopic nature of the dark matter.

  2. Swift multi-wavelength observations of the high-redshift Blazar S5 0836+710 (4C 71.07)

    Science.gov (United States)

    Vercellone, Stefano; Romano, Patrizia; Raiteri, Claudia Maria; Acosta Pulido, Jose; Villata, Massimo; Carnerero Martin, Maria Isabel

    2016-04-01

    We present the preliminary results of a year-long Swift monitoring campaign of the high-redshift (z=2.172) flat-spectrum radio quasar (FSRQ) S5 0836+710 (4C 71.07). The campaign, based on one observation per month, 5 ks each observation, for 12 months, allowed us to investigate the synchrotron and nuclear emission contributions to the optical-UV frequency range of its spectral energy distribution and the X-ray spectral variations along a baseline of a year. We obtained a high-accuracy determination of UVOT magnitudes, an X-ray photon index with an uncertainty of the order of 5%, and well-sampled light curves both in the optical-UV and X-ray energy bands to study their possible modulations and correlations. Our study allowed us to exploit the unique Swift capabilities in terms of both simultaneous energy coverage and schedule flexibility. The Swift monitoring campaign was supported by observations by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) Collaboration, which provided radio, near-infrared, and optical photometric data as well as optical polarimetry. Moreover, a spectroscopic monitoring was obtained at the William Herschel Telescope (WHT) and the Nordic Optical Telescope (NOT). All these observations will allow us to obtain a comprehensive picture of the jet as well as of the nuclear source emission.

  3. The long lives of giant clumps and the birth of outflows in gas-rich galaxies at high redshift

    Energy Technology Data Exchange (ETDEWEB)

    Bournaud, Frédéric; Renaud, Florent; Daddi, Emanuele; Duc, Pierre-Alain; Elbaz, David; Gabor, Jared M.; Juneau, Stéphanie; Kraljic, Katarina; Le Floch' , Emeric [CEA, IRFU/SAp, F-91191 Gif-Sur-Yvette (France); Perret, Valentin; Amram, Philippe; Epinat, Benoit [Aix Marseille Université, CNRS, LAM (Laboratoire d' Astrophysique de Marseille), F-13388 Marseille (France); Dekel, Avishai [Center for Astrophysics and Planetary Science, Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Elmegreen, Bruce G. [IBM Research Division, T.J. Watson Research Center, Yorktown Heights, NY 10598 (United States); Elmegreen, Debra M. [Department of Physics and Astronomy, Vassar College, Poughkeepsie, NY 12604 (United States); Teyssier, Romain [Institute for Theoretical Physics, University of Zurich, CH-8057 Zurich (Switzerland)

    2014-01-01

    Star-forming disk galaxies at high redshift are often subject to violent disk instability, characterized by giant clumps whose fate is yet to be understood. The main question is whether the clumps disrupt within their dynamical timescale (≤50 Myr), like the molecular clouds in today's galaxies, or whether they survive stellar feedback for more than a disk orbital time (≈300 Myr) in which case they can migrate inward and help building the central bulge. We present 3.5-7 pc resolution adaptive mesh refinement simulations of high-redshift disks including photoionization, radiation pressure, and supernovae feedback. Our modeling of radiation pressure determines the mass loading and initial velocity of winds from basic physical principles. We find that the giant clumps produce steady outflow rates comparable to and sometimes somewhat larger than their star formation rate, with velocities largely sufficient to escape the galaxy. The clumps also lose mass, especially old stars, by tidal stripping, and the stellar populations contained in the clumps hence remain relatively young (≤200 Myr), as observed. The clumps survive gaseous outflows and stellar loss, because they are wandering in gas-rich turbulent disks from which they can reaccrete gas at high rates compensating for outflows and tidal stripping, overall keeping realistic and self-regulated gaseous and stellar masses. The outflow and accretion rates have specific timescales of a few 10{sup 8} yr, as opposed to rapid and repeated dispersion and reformation of clumps. Our simulations produce gaseous outflows with velocities, densities, and mass loading consistent with observations, and at the same time suggest that the giant clumps survive for hundreds of Myr and complete their migration to the center of high-redshift galaxies. These long-lived clumps are gas-dominated and contain a moderate mass fraction of stars; they drive inside-out disk evolution, thickening, spheroid growth, and fueling of the central

  4. A unified model for the maximum mass scales of molecular clouds, stellar clusters and high-redshift clumps

    Science.gov (United States)

    Reina-Campos, Marta; Kruijssen, J. M. Diederik

    2017-08-01

    We present a simple, self-consistent model to predict the maximum masses of giant molecular clouds (GMCs), stellar clusters and high-redshift clumps as a function of the galactic environment. Recent works have proposed that these maximum masses are set by shearing motions and centrifugal forces, but we show that this idea is inconsistent with the low masses observed across an important range of local-Universe environments, such as low-surface density galaxies and galaxy outskirts. Instead, we propose that feedback from young stars can disrupt clouds before the global collapse of the shear-limited area is completed. We develop a shear-feedback hybrid model that depends on three observable quantities: the gas surface density, the epicylic frequency and the Toomre parameter. The model is tested in four galactic environments: the Milky Way, the Local Group galaxy M31, the spiral galaxy M83 and the high-redshift galaxy zC406690. We demonstrate that our model simultaneously reproduces the observed maximum masses of GMCs, clumps and clusters in each of these environments. We find that clouds and clusters in M31 and in the Milky Way are feedback-limited beyond radii of 8.4 and 4 kpc, respectively, whereas the masses in M83 and zC406690 are shear-limited at all radii. In zC406690, the maximum cluster masses decrease further due to their inspiral by dynamical friction. These results illustrate that the maximum masses change from being shear-limited to being feedback-limited as galaxies become less gas rich and evolve towards low shear. This explains why high-redshift clumps are more massive than GMCs in the local Universe.

  5. Star-forming galactic contrails as a source of metal enrichment and ionizing radiation at high redshift

    Science.gov (United States)

    Rauch, Michael; Becker, George D.; Haehnelt, Martin G.; Gauthier, Jean-Rene

    2014-06-01

    A spectroscopically detected Lyman α emitting halo at redshift 3.216 in the GOODS-N field is found to reside at the convergence of several line-emitting filaments. Spatially extended emission apparently by He II 1640 Å and several metal transitions is seen within several arcseconds from the position of the central galaxy. The V = 24.9 galaxy mainly responsible for the continuum emission at the centre of the halo has broad-band colours and spectral features consistent with a z = 3.216 star-forming galaxy. Hubble Space Telescope images show that some of the filaments coincide, in projection, with several, mostly blue galaxies, with pronounced head-tail structures partly aligned with each other. These objects, for which we cannot rule that they are foreground, chance projections in front of the high-redshift halo, are seen over an area with a linear extent of at least 12 arcsec. The broad-band images of some galaxies suggest the presence of ram-pressure stripping, including possible evidence for recent star formation in the stripped contrails. Spatial gradients in the appearance of several galaxies may represent a stream of galaxies passing from a colder to a hotter intergalactic medium. The release of the enriched interstellar medium from galaxies and the occurrence of star formation and stellar feedback in the galactic contrails suggest a mechanism for the metal enrichment of the high-redshift intergalactic medium that does not require long-range galactic winds. If these galaxies are at the same redshift as the Lyα halo, their very blue colours may be a consequence of the stripping of gas. A stripped stellar population and star formation in galactic contrails suggest promising sites for the escape of ionizing radiation from high-redshift galaxies.

  6. Imaging Cold Gas to 1 kpc scales in high-redshift galaxies with the ngVLA

    Science.gov (United States)

    Casey, Caitlin; Narayanan, Desika; Dave, Romeel; Hung, Chao-Ling; Champagne, Jaclyn; Carilli, Chris Luke; Decarli, Roberto; Murphy, Eric J.; Popping, Gergo; Riechers, Dominik; Somerville, Rachel S.; Walter, Fabian

    2017-01-01

    The next generation Very Large Array (ngVLA) will revolutionize our understanding of the distant Universe via the detection of cold molecular gas in the first galaxies. Its impact on studies of galaxy characterization via detailed gas dynamics will provide crucial insight on dominant physical drivers for star-formation in high redshift galaxies, including the exchange of gas from scales of the circumgalactic medium down to resolved clouds on mass scales of ~10^5 M_sun. In this study, we employ a series of high-resolution, cosmological, hydrodynamic zoom simulations from the MUFASA simulation suite and a CASA simulator to generate mock ngVLA observations. Based on a direct comparison between the inferred results from our mock observations and the cosmological simulations, we investigate the capabilities of ngVLA to constrain the mode of star formation, dynamical mass, and molecular gas kinematics in individual high-redshift galaxies using cold gas tracers like CO(1-0) and CO(2-1). Using the Despotic radiative transfer code that encompasses simultaneous thermal and statistical equilibrium in calculating the molecular and atomic level populations, we generate parallel mock observations of high-J transitions of CO and C+ from ALMA for comparison. The factor of 100 times improvement in mapping speed for the ngVLA beyond the Jansky VLA and the proposed ALMA Band 1 will make these detailed, high-resolution imaging and kinematic studies routine at z=2 and beyond.

  7. A LINK TO THE PAST: USING MARKOV CHAIN MONTE CARLO FITTING TO CONSTRAIN FUNDAMENTAL PARAMETERS OF HIGH-REDSHIFT GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Pirzkal, N.; Rothberg, B.; Koekemoer, Anton [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Nilsson, Kim K. [ST-ECF, Karl-Schwarzschild-Strasse 2, 85748 Garching bei Muenchen (Germany); Finkelstein, S. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Malhotra, Sangeeta; Rhoads, James, E-mail: npirzkal@stsci.edu [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States)

    2012-04-01

    We have developed a new method for fitting spectral energy distributions (SEDs) to identify and constrain the physical properties of high-redshift (4 < z < 8) galaxies. Our approach uses an implementation of Bayesian based Markov Chain Monte Carlo that we have dubbed '{pi}MC{sup 2}'. It allows us to compare observations to arbitrarily complex models and to compute 95% credible intervals that provide robust constraints for the model parameters. The work is presented in two sections. In the first, we test {pi}MC{sup 2} using simulated SEDs to not only confirm the recovery of the known inputs but to assess the limitations of the method and identify potential hazards of SED fitting when applied specifically to high-redshift (z > 4) galaxies. In the second part of the paper we apply {pi}MC{sup 2} to thirty-three 4 < z < 8 objects, including the spectroscopically confirmed Grism ACS Program for Extragalactic Science Ly{alpha} sample (4 < z < 6), supplemented by newly obtained Hubble Space Telescope/WFC3 near-IR observations, and several recently reported broadband selected z > 6 galaxies. Using {pi}MC{sup 2}, we are able to constrain the stellar mass of these objects and in some cases their stellar age and find no evidence that any of these sources formed at a redshift larger than z = 8, a time when the universe was Almost-Equal-To 0.6 Gyr old.

  8. The Final SDSS High-redshift Quasar Sample of 52 Quasars at z>5.7

    Science.gov (United States)

    Jiang, Linhua; McGreer, Ian D.; Fan, Xiaohui; Strauss, Michael A.; Bañados, Eduardo; Becker, Robert H.; Bian, Fuyan; Farnsworth, Kara; Shen, Yue; Wang, Feige; Wang, Ran; Wang, Shu; White, Richard L.; Wu, Jin; Wu, Xue-Bing; Yang, Jinyi; Yang, Qian

    2016-12-01

    We present the discovery of nine quasars at z˜ 6 identified in the Sloan Digital Sky Survey (SDSS) imaging data. This completes our survey of z˜ 6 quasars in the SDSS footprint. Our final sample consists of 52 quasars at 5.7\\lt z≤slant 6.4, including 29 quasars with {z}{AB}≤slant 20 mag selected from 11,240 deg2 of the SDSS single-epoch imaging survey (the main survey), 10 quasars with 20≤slant {z}{AB}≤slant 20.5 selected from 4223 deg2 of the SDSS overlap regions (regions with two or more imaging scans), and 13 quasars down to {z}{AB}≈ 22 mag from the 277 deg2 in Stripe 82. They span a wide luminosity range of -29.0≤slant {M}1450≤slant -24.5. This well-defined sample is used to derive the quasar luminosity function (QLF) at z˜ 6. After combining our SDSS sample with two faint ({M}1450≥slant -23 mag) quasars from the literature, we obtain the parameters for a double power-law fit to the QLF. The bright-end slope β of the QLF is well constrained to be β =-2.8+/- 0.2. Due to the small number of low-luminosity quasars, the faint-end slope α and the characteristic magnitude {M}1450* are less well constrained, with α =-{1.90}-0.44+0.58 and {M}* =-{25.2}-3.8+1.2 mag. The spatial density of luminous quasars, parametrized as ρ ({M}1450\\lt -26,z)=ρ (z=6){10}k(z-6), drops rapidly from z˜ 5 to 6, with k=-0.72+/- 0.11. Based on our fitted QLF and assuming an intergalactic medium (IGM) clumping factor of C = 3, we find that the observed quasar population cannot provide enough photons to ionize the z˜ 6 IGM at ˜90% confidence. Quasars may still provide a significant fraction of the required photons, although much larger samples of faint quasars are needed for more stringent constraints on the quasar contribution to reionization.

  9. Infrared

    Science.gov (United States)

    Vollmer, M.

    2013-11-01

    'Infrared' is a very wide field in physics and the natural sciences which has evolved enormously in recent decades. It all started in 1800 with Friedrich Wilhelm Herschel's discovery of infrared (IR) radiation within the spectrum of the Sun. Thereafter a few important milestones towards widespread use of IR were the quantitative description of the laws of blackbody radiation by Max Planck in 1900; the application of quantum mechanics to understand the rotational-vibrational spectra of molecules starting in the first half of the 20th century; and the revolution in source and detector technologies due to micro-technological breakthroughs towards the end of the 20th century. This has led to much high-quality and sophisticated equipment in terms of detectors, sources and instruments in the IR spectral range, with a multitude of different applications in science and technology. This special issue tries to focus on a few aspects of the astonishing variety of different disciplines, techniques and applications concerning the general topic of infrared radiation. Part of the content is based upon an interdisciplinary international conference on the topic held in 2012 in Bad Honnef, Germany. It is hoped that the information provided here may be useful for teaching the general topic of electromagnetic radiation in the IR spectral range in advanced university courses for postgraduate students. In the most general terms, the infrared spectral range is defined to extend from wavelengths of 780 nm (upper range of the VIS spectral range) up to wavelengths of 1 mm (lower end of the microwave range). Various definitions of near, middle and far infrared or thermal infrared, and lately terahertz frequencies, are used, which all fall in this range. These special definitions often depend on the scientific field of research. Unfortunately, many of these fields seem to have developed independently from neighbouring disciplines, although they deal with very similar topics in respect of the

  10. Planck 2013 results. XVIII. The gravitational lensing-infrared background correlation

    DEFF Research Database (Denmark)

    Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.

    2013-01-01

    of these two unique probes allows us to measure directly the connection between dark and luminous matter in the high redshift (1 = 1. We measure directly the SFR density with around 2 sigma significance for three redshift bins between z = 1 and 7, thus opening a new window into the study of the formation...

  11. CLUES to the past: Local Group progenitors amongst high-redshift Lyman break galaxies

    Science.gov (United States)

    Dayal, Pratika; Libeskind, Noam I.; Dunlop, James S.

    2013-06-01

    We use state-of-the-art numerical simulations to explore the observability and the expected physical properties of the progenitors of the Local Group galaxies at z ≃ 6-8, within 1 billion years of the big bang. We find that the most massive progenitors of the Milky Way (MW) and Andromeda (M31) at z ≃ 6 and 7 are predicted to have absolute ultraviolet (UV) continuum magnitudes MUV ≃ -17 to -18, suggesting that their analogues lie close to the detection limits of the deepest near-infrared (IR) surveys conducted to date [i.e. Hubble Space Telescope Wide Field Camera 3/IR Ultra Deep Field (UDF)12]. This in turn confirms that the majority of currently known z ≃ 6-8 galaxies are expected to be the seeds of present-day galaxies which are more massive than L* spirals. We also discuss the properties of the Local Group progenitors at these early epochs, extending down to absolute magnitudes MUV ≃ -13. The most massive MW/M31 progenitors at z ≃ 7 have stellar masses M* ≃ 107.5-8 M⊙, stellar metallicities Z* ˜ 3-6 per cent Z⊙, and predicted observed UV continuum slopes β ≃ -2.4 to -2.5.

  12. Simulating the detection and classification of high-redshift supernovae with HARMONI on the ELT

    Science.gov (United States)

    Bounissou, S.; Thatte, N.; Zieleniewski, S.; Houghton, R. C. W.; Tecza, M.; Hook, I.; Neichel, B.; Fusco, T.

    2018-02-01

    We present detailed simulations of integral field spectroscopic observations of a supernova in a host galaxy at z ˜ 3, as observed by the HARMONI spectrograph on the Extremely Large Telescope, asssisted by laser tomographic adaptive optics. The goal of the simulations, using the HSIM simulation tool, is to determine whether HARMONI can discern the supernova Type from spectral features in the supernova spectrum. We find that in a 3 hour observation, covering the near-infrared H and K bands, at a spectral resolving power of ˜3000, and using the 20×20 mas spaxel scale, we can classify supernova Type Ia and their redshift robustly up to 80 days past maximum light (20 days in the supernova rest frame). We show that HARMONI will provide spectra at z ˜ 3 that are of comparable (or better) quality to the best spectra we can currently obtain at z ˜ 1, thus allowing studies of cosmic expansion rates to be pushed to substantially higher redshifts.

  13. The variance of dispersion measure of high-redshift transient objects as a probe of ionized bubble size during reionization

    Science.gov (United States)

    Yoshiura, Shintaro; Takahashi, Keitaro

    2018-01-01

    The dispersion measure (DM) of high-redshift (z ≳ 6) transient objects such as fast radio bursts can be a powerful tool to probe the intergalactic medium during the Epoch of Reionization. In this paper, we study the variance of the DMs of objects with the same redshift as a potential probe of the size distribution of ionized bubbles. We calculate the DM variance with a simple model with randomly distributed spherical bubbles. It is found that the DM variance reflects the characteristics of the probability distribution of the bubble size. We find that the variance can be measured precisely enough to obtain the information on the typical size with a few hundred sources at a single redshift.

  14. THERMAL AND RADIATIVE ACTIVE GALACTIC NUCLEUS FEEDBACK HAVE A LIMITED IMPACT ON STAR FORMATION IN HIGH-REDSHIFT GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Roos, Orianne; Juneau, Stéphanie; Bournaud, Frédéric; Gabor, Jared M., E-mail: orianne.roos@cea.fr [CEA-Saclay, F-91190 Gif-sur-Yvette (France)

    2015-02-10

    The effects of active galactic nuclei (AGNs) on their host galaxies depend on the coupling between the injected energy and the interstellar medium (ISM). Here, we model and quantify the impact of long-range AGN ionizing radiation—in addition to the often considered small-scale energy deposition—on the physical state of the multi-phase ISM of the host galaxy and on its total star formation rate (SFR). We formulate an AGN spectral energy distribution matched with observations, which we use with the radiative transfer (RT) code Cloudy to compute AGN ionization in a simulated high-redshift disk galaxy. We use a high-resolution (∼6 pc) simulation including standard thermal AGN feedback and calculate RT in post-processing. Surprisingly, while these models produce significant AGN-driven outflows, we find that AGN ionizing radiation and heating reduce the SFR by a few percent at most for a quasar luminosity (L {sub bol} = 10{sup 46.5} erg s{sup –1}). Although the circumgalactic gaseous halo can be kept almost entirely ionized by the AGN, most star-forming clouds (n ≳ 10{sup 2} {sup –} {sup 3} cm{sup –3}) and even the reservoirs of cool atomic gas (n ∼ 0.3-10 cm{sup –3})—which are the sites of future star formation (SF; 100-200 Myr), are generally too dense to be significantly affected. Our analysis ignores any absorption from a putative torus, making our results upper limits on the effects of ionizing radiation. Therefore, while the AGN-driven outflows can remove substantial amounts of gas in the long term, the impact of AGN feedback on the SF efficiency in the interstellar gas in high-redshift galaxies is marginal, even when long-range radiative effects are accounted for.

  15. How Environment Affects Star Formation: Tracing Activity in High Redshift Galaxy Clusters

    Science.gov (United States)

    Alberts, Stacey; Pope, A.; Brodwin, M.; Atlee, D. W.; Lin, Y.; Chary, R.; Dey, A.; Eisenhardt, P. R.; Gettings, D.; Gonzalez, A. H.; Jannuzi, B.; Mancone, C.; Moustakas, J.; Snyder, G. F.; Stanford, S. A.; Stern, D.; Weiner, B. J.; Zeimann, G.

    2014-01-01

    The emerging picture of the evolution of cluster galaxies indicates that the epoch of z>1 is a crucial period of active star formation and mass assembly in clusters. In this dissertation, I leverage a uniformly-selected cluster sample from the IRAC Shallow Cluster Survey (ISCS) with Herschel imaging to analyse the star formation (SF) activity in cluster galaxies over the past ten billion years. This analysis is two-fold: 1) using 274 clusters across the 9 square degree Bootes field, I perform a stacking analysis of mass-limited samples of cluster and field galaxies using wide-field Herschel observations over a long redshift baseline, z=0.3-1.5. I find that the average SF activity in cluster galaxies is evolving faster than in the field, with field-like SF in the cluster cores and enhanced SF activity in the cluster outskirts at z>1.2. By further breaking down my analysis by galaxy mass and type, I determine which mechanisms are capable of driving this evolution. 2) I use unique, deep Herschel imaging of 11 spectroscopically-confirmed clusters from z=1.1-1.8 to study the properties of individual infrared bright cluster galaxies as a function of redshift and cluster-centric radius. Combined with ancillary data, I determine the star formation, dust, and AGN properties of the most active cluster galaxies and tie the evolution of these properties back to the environment by comparing to field populations. By combining these two approaches, I constrain cluster galaxy properties during a pivotal epoch of dust-obscured star formation activity and mass assembly in some of the most extreme structures in the Universe.

  16. The radio spectral energy distribution of infrared-faint radio sources

    NARCIS (Netherlands)

    Herzog, A.; Norris, R. P.; Middelberg, E.; Seymour, N.; Spitler, L. R.; Emonts, B. H. C.; Franzen, T. M. O.; Hunstead, R.; Intema, H. T.; Marvil, J.; Parker, Q. A.; Sirothia, S. K.; Hurley-Walker, N.; Bell, M.; Bernardi, G.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Callingham, J. R.; Deshpande, A. A.; Dwarakanath, K. S.; For, B. -Q; Greenhill, L. J.; Hancock, P.; Hazelton, B. J.; Hindson, L.; Johnston-Hollitt, M.; Kapińska, A. D.; Kaplan, D. L.; Lenc, E.; Lonsdale, C. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Morgan, J.; Oberoi, D.; Offringa, A.; Ord, S. M.; Prabu, T.; Procopio, P.; Udaya Shankar, N.; Srivani, K. S.; Staveley-Smith, L.; Subrahmanyan, R.; Tingay, S. J.; Wayth, R. B.; Webster, R. L.; Williams, A.; Williams, C. L.; Wu, C.; Zheng, Q.; Bannister, K. W.; Chippendale, A. P.; Harvey-Smith, L.; Heywood, I.; Indermuehle, B.; Popping, A.; Sault, R. J.; Whiting, M. T.

    2016-01-01

    Context. Infrared-faint radio sources (IFRS) are a class of radio-loud (RL) active galactic nuclei (AGN) at high redshifts (z ≥ 1.7) that are characterised by their relative infrared faintness, resulting in enormous radio-to-infrared flux density ratios of up to several thousand. Aims: Because of

  17. THE STAR FORMATION HISTORY OF BCGs TO z = 1.8 FROM THE SpARCS/SWIRE SURVEY: EVIDENCE FOR SIGNIFICANT IN SITU STAR FORMATION AT HIGH REDSHIFT

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Tracy M. A.; Bonaventura, Nina [McGill University, 3600 rue University, Montreal, QC H3A 2T8 (Canada); Muzzin, Adam [Leiden Observatory, University of Leiden, P.O. Box 9514, 2300 RA Leiden (Netherlands); Noble, Allison; Yee, H. K. C. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Geach, James [Centre for Astrophysics Research, University of Hertfordshire, Hatfield, Hertfordshire AL109AB (United Kingdom); Hezevah, Yashar [Kavli Institue for Particle Physics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305-4085 (United States); Lidman, Chris [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); Wilson, Gillian [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Surace, Jason [Spitzer Science Center, California Institute of Technology, M/S 314-6, Pasadena, CA 91125 (United States); Shupe, David [NASA Herschel Science Center, IPAC, 770 South Wilson Avenue, Pasadena, CA 91125 (United States)

    2015-12-01

    We present the results of an MIPS-24 μm study of the brightest cluster galaxies (BCGs) of 535 high-redshift galaxy clusters. The clusters are drawn from the Spitzer Adaptation of the Red-Sequence Cluster Survey, which effectively provides a sample selected on total stellar mass, over 0.2 < z < 1.8 within the Spitzer Wide-Area Infrared Extragalactic (SWIRE) Survey fields. Twenty percent, or 106 clusters, have spectroscopically confirmed redshifts, and the rest have redshifts estimated from the color of their red sequence. A comparison with the public SWIRE images detects 125 individual BCGs at 24 μm ≳ 100 μJy, or 23%. The luminosity-limited detection rate of BCGs in similar richness clusters (N{sub gal} > 12) increases rapidly with redshift. Above z ∼ 1, an average of ∼20% of the sample have 24 μm inferred infrared luminosities of L{sub IR} > 10{sup 12} L{sub ⊙}, while the fraction below z ∼ 1 exhibiting such luminosities is <1%. The Spitzer-IRAC colors indicate the bulk of the 24 μm detected population is predominantly powered by star formation, with only 7/125 galaxies lying within the color region inhabited by active galactic nuclei (AGNs). Simple arguments limit the star formation activity to several hundred million years and this may therefore be indicative of the timescale for AGN feedback to halt the star formation. Below redshift z ∼ 1, there is not enough star formation to significantly contribute to the overall stellar mass of the BCG population, and therefore BCG growth is likely dominated by dry mergers. Above z ∼ 1, however, the inferred star formation would double the stellar mass of the BCGs and is comparable to the mass assembly predicted by simulations through dry mergers. We cannot yet constrain the process driving the star formation for the overall sample, though a single object studied in detail is consistent with a gas-rich merger.

  18. Paul Callaghan luminous moments

    CERN Document Server

    Callaghan, Paul

    2013-01-01

    Acknowledged internationally for his ground-breaking scientific research in the field of magnetic resonance, Sir Paul Callaghan was a scientist and visionary with a rare gift for promoting science to a wide audience. He was named New Zealander of the Year in 2011. His death in early 2012 robbed New Zealand of an inspirational leader. Paul Callaghan: Luminous Moments brings together some of his most significant writing. Whether he describes his childhood in Wanganui, reflects on discovering the beauty of science, sets out New Zealand's future potential or discusses the experience of fa

  19. Binocular combination of luminance profiles.

    Science.gov (United States)

    Ding, Jian; Levi, Dennis M

    2017-11-01

    We develop and test a new two-dimensional model for binocular combination of the two eyes' luminance profiles. For first-order stimuli, the model assumes that one eye's luminance profile first goes through a luminance compressor, receives gain-control and gain-enhancement from the other eye, and then linearly combines the other eye's output profile. For second-order stimuli, rectification is added in the signal path of the model before the binocular combination site. Both the total contrast and luminance energies, weighted sums over both the space and spatial-frequency domains, were used in the interocular gain-control, while only the total contrast energy was used in the interocular gain-enhancement. To challenge the model, we performed a binocular brightness matching experiment over a large range of background and target luminances. The target stimulus was a dichoptic disc with a sharp edge that has an increment or decrement luminance from its background. The disk's interocular luminance ratio varied from trial to trial. To refine the model we tested three luminance compressors, five nested binocular combination models (including the Ding-Sperling and the DSKL models), and examined the presence or absence of total luminance energy in the model. We found that (1) installing a luminance compressor, either a logarithmic luminance function or luminance gain-control, (2) including both contrast and luminance energies, and (3) adding interocular gain-enhancement (the DSKL model) to a combined model significantly improved its performance. The combined model provides a systematic account of binocular luminance summation over a large range of luminance input levels. It gives a unified explanation of Fechner's paradox observed on a dark background, and a winner-take-all phenomenon observed on a light background. To further test the model, we conducted two additional experiments: luminance summation of discs with asymmetric contour information (Experiment 2), similar to

  20. THE RADIO PROPERTIES OF HIGH-REDSHIFT QUASARS .1. DUAL-FREQUENCY OBSERVATIONS OF 79 STEEP-SPECTRUM QUASARS AT Z-GREATER-THAN-1.5

    NARCIS (Netherlands)

    LONSDALE, CJ; BARTHEL, PD; MILEY, GK

    We have made sensitive VLA observations of virtually all known high-redshift (z > 1.5) radio-loud QSOs with extended radio morphologies. The resulting images (at 6 and 2 cm wavelength, including linear polarization) have angular resolutions of typically 0.''4 and 0.''15 and are compiled here. This

  1. Fluctuating feedback-regulated escape fraction of ionizing radiation in low-mass, high-redshift galaxies

    Science.gov (United States)

    Trebitsch, Maxime; Blaizot, Jérémy; Rosdahl, Joakim; Devriendt, Julien; Slyz, Adrianne

    2017-09-01

    Low-mass galaxies are thought to provide the bulk of the ionizing radiation necessary to reionize the Universe. The amount of photons escaping the galaxies is poorly constrained theoretically, and difficult to measure observationally. Yet it is an essential parameter of reionization models. We study in detail how ionizing radiation can leak from high-redshift galaxies. For this purpose, we use a series of high-resolution radiation hydrodynamics simulations, zooming on three dwarf galaxies in a cosmological context. We find that the energy and momentum input from the supernova explosions has a pivotal role in regulating the escape fraction by disrupting dense star-forming clumps, and clearing sightlines in the halo. In the absence of supernovae, photons are absorbed very locally, within the birth clouds of massive stars. We follow the time evolution of the escape fraction and find that it can vary by more than six orders of magnitude. This explains the large scatter in the value of the escape fraction found by previous studies. This fast variability also impacts the observability of the sources of reionization: a survey even as deep as M1500 = -14 would miss about half of the underlying population of Lyman-continuum emitters.

  2. Efficient cold outflows driven by cosmic rays in high redshift galaxies and their global effects on the IGM

    Science.gov (United States)

    Samui, Saumyadip; Subramanian, Kandaswamy; Srianand, Raghunathan

    2018-02-01

    We present semi-analytical models of galactic outflows in high redshift galaxies driven by both hot thermal gas and non-thermal cosmic rays. Thermal pressure alone may not sustain a large scale outflow in low mass galaxies (i.e M ˜ 108 M⊙), in the presence of supernovae (SNe) feedback with large mass loading. We show that inclusion of cosmic ray pressure allows outflow solutions even in these galaxies. In massive galaxies for the same energy efficiency, cosmic ray driven winds can propagate to larger distances compared to pure thermally driven winds. On an average gas in the cosmic ray driven winds has a lower temperature which could aid detecting it through absorption lines in the spectra of background sources. Using our constrained semi-analytical models of galaxy formation (that explains the observed UV luminosity functions of galaxies) we study the influence of cosmic ray driven winds on the properties of the intergalactic medium (IGM) at different redshifts. In particular, we study the volume filling factor, average metallicity, cosmic ray and magnetic field energy densities for models invoking atomic cooled and molecular cooled halos. We show that the cosmic rays in the IGM could have enough energy that can be transferred to the thermal gas in presence of magnetic fields to influence the thermal history of the intergalactic medium. The significant volume filling and resulting strength of IGM magnetic fields can also account for recent γ-ray observations of blazars.

  3. Newborn spheroids at high redshift: when and how did the dominant, old stars in today's massive galaxies form?

    Science.gov (United States)

    Kaviraj, S.; Cohen, S.; Ellis, R. S.; Peirani, S.; Windhorst, R. A.; O'Connell, R. W.; Silk, J.; Whitmore, B. C.; Hathi, N. P.; Ryan, R. E.; Dopita, M. A.; Frogel, J. A.; Dekel, A.

    2013-01-01

    We study ˜330 massive (M* > 109.5 M⊙), newborn spheroidal galaxies (SGs) around the epoch of peak star formation (1 explore the high-redshift origin of SGs and gain insight into when and how the old stellar populations that dominate today's Universe formed. The sample is drawn from the Hubble Space Telescope (HST)/WFC3 Early-Release Science programme, which provides deep 10-filter (0.2-1.7 μm) HST imaging over one-third of the GOODS-South field. We find that the star formation episodes that built our SGs likely peaked in the redshift range 2 values ( 1010.5 M⊙, and an age trend becomes evident in this mass regime: SGs with M* > 1011.5 M⊙ are ˜2 Gyr older than their counterparts with M* violent disc instability driven by cold streams and/or minor mergers) likely play a dominant role in building SGs, and creating a significant fraction of the old stellar populations that dominate today's Universe.

  4. Comparing Low-Redshift Compact Dwarf Starbursts in the RESOLVE Survey with High-Redshift Blue Nuggets

    Science.gov (United States)

    Palumbo, Michael Louis; Kannappan, Sheila; Snyder, Elaine; Eckert, Kathleen; Norman, Dara; Fraga, Luciano; Quint, Bruno; Amram, Philippe; Mendes de Oliveira, Claudia; RESOLVE Team

    2018-01-01

    We identify and characterize a population of compact dwarf starburst galaxies in the RESOLVE survey, a volume-limited census of galaxies in the local universe, to probe the possibility that these galaxies are related to “blue nuggets,” a class of intensely star-forming and compact galaxies previously identified at high redshift. Blue nuggets are thought to form as the result of intense compaction events that drive fresh gas to their centers. They are expected to display prolate morphology and rotation along their minor axes. We report IFU observations of three of our compact dwarf starburst galaxies, from which we construct high-resolution velocity fields, examining the evidence for minor axis or otherwise misaligned rotation. We find multiple cases of double nuclei in our sample, which may be indicative of a merger origin as in some blue nugget formation scenarios. We compare the masses, radii, gas-to-stellar mass ratios, star formation rates, stellar surface mass densities, and environmental contexts of our sample to expectations for blue nuggets.

  5. The combined effect of AGN and supernovae feedback in launching massive molecular outflows in high-redshift galaxies

    Science.gov (United States)

    Biernacki, Pawel; Teyssier, Romain

    2018-01-01

    We have recently improved our model of active galactic nucleus (AGN) by attaching the supermassive black hole (SMBH) to a massive nuclear star cluster (NSC). Here we study the effects of this new model in massive, gas-rich galaxies with several simulations of different feedback recipes with the hydrodynamics code RAMSES. These simulations are compared to a reference simulation without any feedback, in which the cooling halo gas is quickly consumed in a burst of star formation. In the presence of strong supernovae (SN) feedback, we observe the formation of a galactic fountain that regulates star formation over a longer period, but without halting it. If only AGN feedback is considered, as soon as the SMBH reaches a critical mass, strong outflows of hot gas are launched and prevent the cooling halo gas from reaching the disk, thus efficiently halting star formation, leading to the so-called "quenching". If both feedback mechanisms act in tandem, we observe a non-linear coupling, in the sense that the dense gas in the supernovae-powered galactic fountain is propelled by the hot outflow powered by the AGN at much larger radii than without AGN. We argue that these particular outflows are able to unbind dense gas from the galactic halo, thanks to the combined effect of SN and AGN feedback. We speculate that this mechanism occurs at the end of the fast growing phase of SMBH, and is at the origin of the dense molecular outflows observed in many massive high-redshift galaxies.

  6. Constraining Emission Models of Luminous Blazar Sources

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, Marek; /Warsaw, Copernicus Astron. Ctr.; Stawarz, Lukasz; /Kipac, Menlo Park /Jagiellonian U., Astron. Observ. /SLAC; Moderski, Rafal; Nalewajko, Krzysztof; /Warsaw, Copernicus Astron. Ctr.; Madejski, Greg; /KIPAC, Menlo Park /SLAC

    2009-10-30

    Many luminous blazars which are associated with quasar-type active galactic nuclei display broad-band spectra characterized by a large luminosity ratio of their high-energy ({gamma}-ray) and low-energy (synchrotron) spectral components. This large ratio, reaching values up to 100, challenges the standard synchrotron self-Compton models by means of substantial departures from the minimum power condition. Luminous blazars have also typically very hard X-ray spectra, and those in turn seem to challenge hadronic scenarios for the high energy blazar emission. As shown in this paper, no such problems are faced by the models which involve Comptonization of radiation provided by a broad-line-region, or dusty molecular torus. The lack or weakness of bulk Compton and Klein-Nishina features indicated by the presently available data favors production of {gamma}-rays via up-scattering of infrared photons from hot dust. This implies that the blazar emission zone is located at parsec-scale distances from the nucleus, and as such is possibly associated with the extended, quasi-stationary reconfinement shocks formed in relativistic outflows. This scenario predicts characteristic timescales for flux changes in luminous blazars to be days/weeks, consistent with the variability patterns observed in such systems at infrared, optical and {gamma}-ray frequencies. We also propose that the parsec-scale blazar activity can be occasionally accompanied by dissipative events taking place at sub-parsec distances and powered by internal shocks and/or reconnection of magnetic fields. These could account for the multiwavelength intra-day flares occasionally observed in powerful blazars sources.

  7. 78 FR 68100 - Luminant Generation Company, LLC

    Science.gov (United States)

    2013-11-13

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Luminant Generation Company, LLC AGENCY: U.S. Nuclear Regulatory Commission (NRC). ACTION... consecutive weeks of a combined license (COL) application from Luminant Generation Company, LLC. (Luminant...

  8. 78 FR 69710 - Luminant Generation Company, LLC

    Science.gov (United States)

    2013-11-20

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Luminant Generation Company, LLC AGENCY: U.S. Nuclear Regulatory Commission (NRC). ACTION... consecutive weeks of a combined license (COL) application from Luminant Generation Company, LLC. (Luminant...

  9. 78 FR 66785 - Luminant Generation Company, LLC

    Science.gov (United States)

    2013-11-06

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Luminant Generation Company, LLC AGENCY: Nuclear Regulatory Commission. ACTION: Notice of receipt... consecutive weeks of ] a combined license (COL) application from Luminant Generation Company, LLC. (Luminant...

  10. Luminance controlled pupil size affects Landolt C task performance

    Energy Technology Data Exchange (ETDEWEB)

    Berman, S.M. (Lawrence Berkeley Lab., CA (United States)); Fein, G. (Neurobehavioral Lab. Software, San Rafael, CA (United States)); Jewett, D.L.; Ashford, F. (ABRATech Corp., Mill Valley, CA (United States))

    1993-02-01

    Subjects judged the orientation of a 2 min. gap Landolt C located at a distance of 2.4 m. The stimuli were presented in central vision on a CRT, at low to medium contrast. The effects of varying the spectrum and luminance of surround lighting were assessed on both pupil size (measured using infrared pupillometry during task performance) and task accuracy. The task display was protected from the surround lighting, so that its luminance and contrast could be varied independently of the changes in the surround lighting. Indirect surround illumination was provided by either two illuminants of very different scotopic spectral content but with the same photopic luminance (Experiments 1 and 3), or by using the same illuminant at two different luminance levels (Experiment 2). In Experiment 3, the effect of changing surround spectrum was compared to the effect of varying task background luminance between 12 cd/m[sup 2] and 73 cd/m[sup 2]. In all experiments, scotopically enhanced surround lighting produced pupil areas which were reduced by almost 50% in comparison with surround lighting with relatively less scotopic luminance. Concomitantly there was improvement in Landolt C task performance with the scotopically enhanced surround lighting at all contrast and luminance levels. In these experiments, smaller pupil sizes were associated with significantly better visual-task performance in spite of lower task retinal illuminance when compared to the condition with larger pupils. These results suggest that changes in surround spectrum can compensate for the effect on task performance of a reduction in task luminance and supports the hypothesis that lighting energy savings could accrue in the workplace by shifting lamp spectra to obtain greater scotopic efficacy.

  11. Luminance controlled pupil size affects Landolt C task performance. Revision

    Energy Technology Data Exchange (ETDEWEB)

    Berman, S.M. [Lawrence Berkeley Lab., CA (United States); Fein, G. [Neurobehavioral Lab. Software, San Rafael, CA (United States); Jewett, D.L.; Ashford, F. [ABRATech Corp., Mill Valley, CA (United States)

    1993-02-01

    Subjects judged the orientation of a 2 min. gap Landolt C located at a distance of 2.4 m. The stimuli were presented in central vision on a CRT, at low to medium contrast. The effects of varying the spectrum and luminance of surround lighting were assessed on both pupil size (measured using infrared pupillometry during task performance) and task accuracy. The task display was protected from the surround lighting, so that its luminance and contrast could be varied independently of the changes in the surround lighting. Indirect surround illumination was provided by either two illuminants of very different scotopic spectral content but with the same photopic luminance (Experiments 1 and 3), or by using the same illuminant at two different luminance levels (Experiment 2). In Experiment 3, the effect of changing surround spectrum was compared to the effect of varying task background luminance between 12 cd/m{sup 2} and 73 cd/m{sup 2}. In all experiments, scotopically enhanced surround lighting produced pupil areas which were reduced by almost 50% in comparison with surround lighting with relatively less scotopic luminance. Concomitantly there was improvement in Landolt C task performance with the scotopically enhanced surround lighting at all contrast and luminance levels. In these experiments, smaller pupil sizes were associated with significantly better visual-task performance in spite of lower task retinal illuminance when compared to the condition with larger pupils. These results suggest that changes in surround spectrum can compensate for the effect on task performance of a reduction in task luminance and supports the hypothesis that lighting energy savings could accrue in the workplace by shifting lamp spectra to obtain greater scotopic efficacy.

  12. Investigating the properties of gamma ray bursts and gravitational wave standard sirens as high redshift distance indicators

    Science.gov (United States)

    Speirits, Fiona Claire

    In a discipline commonly faulted for ad hoc assumptions and models with very little discriminating observational evidence, cosmologists are continually trying, and in many cases succeeding, to improve both the data and models. However, the desire to support currently favoured models often dominates research and may lead to a systematic bias being introduced in favour of a model before a strong body of supporting evidence has been accumulated. This is perhaps most evident in literature supporting the viability of Gamma Ray Bursts as cosmological distance indicators, where aside from subjective data-selection, the basic statistical methods are at best questionable and at worst incorrect. To this end, we construct a simple cosmology-independent illustration of the effect that the application of these methods has on parameter estimation and discuss the correct method to apply to current data. We also investigate the constraints potential future Gamma Ray Burst data may place on alternatives to the status quo Concordance Model in the shape of Conformal Gravity and Unified Dark Matter through a widely applicable and transferable Bayesian model comparison technique and the development of a representative mock data set. Finally, we investigate gravitational wave standard sirens as an alternative high-redshift distance indicator. We first illustrate their strong diagnostic potential through a Bayesian model comparison between the standard Unified Dark Matter model and a variant in which the dark component is redshift dependent. By drawing mock data from a known cosmological model, thus fixing the expected values of the model parameters, we find that while 182 Type 1a Supernovae are readily confused between constant and evolving models, just 2 standard sirens are able to successfully identify the correct model. Having established standard sirens as an effective tool in cosmological model comparison, we then address the potential confusion of models with dynamical dark energy

  13. Properties of z ~ 3-6 Lyman break galaxies. II. Impact of nebular emission at high redshift

    Science.gov (United States)

    de Barros, S.; Schaerer, D.; Stark, D. P.

    2014-03-01

    Context. To gain insight on the mass assembly and place constraints on the star formation history (SFH) of Lyman break galaxies (LBGs), it is important to accurately determine their properties. Aims: We estimate how nebular emission and different SFHs affect parameter estimation of LBGs. Methods: We present a homogeneous, detailed analysis of the spectral energy distribution (SED) of ~1700 LBGs from the GOODS-MUSIC catalogue with deep multi-wavelength photometry from the U band to 8 μm to determine stellar mass, age, dust attenuation, and star formation rate. Using our SED fitting tool, which takes into account nebular emission, we explore a wide parameter space. We also explore a set of different star formation histories. Results: Nebular emission is found to significantly affect the determination of the physical parameters for the majority of z ~ 3-6 LBGs. We identify two populations of galaxies by determining the importance of the contribution of emission lines to broadband fluxes. We find that ~65% of LBGs show detectable signs of emission lines, whereas ~35% show weak or no emission lines. This distribution is found over the entire redshift range. We interpret these groups as actively star-forming and more quiescent LBGs, respectively. We find that it is necessary to considerer SED fits with very young ages (affected by strong emission lines. Other arguments favouring episodic star formation and relatively short star formation timescales are also discussed. Considering nebular emission generally leads to a younger age, lower stellar mass, higher dust attenuation, higher star formation rate, and a large scatter in the SFR-M⋆ relation. Our analysis yields a trend of increasing specific star formation rate with redshift, as predicted by recent galaxy evolution models. Conclusions: The physical parameters of approximately two thirds of high redshift galaxies are significantly modified when we account for nebular emission. The SED models, which include nebular

  14. High-redshift AGN in the Chandra Deep Fields: the obscured fraction and space density of the sub-L* population

    Science.gov (United States)

    Vito, F.; Brandt, W. N.; Yang, G.; Gilli, R.; Luo, B.; Vignali, C.; Xue, Y. Q.; Comastri, A.; Koekemoer, A. M.; Lehmer, B. D.; Liu, T.; Paolillo, M.; Ranalli, P.; Schneider, D. P.; Shemmer, O.; Volonteri, M.; Wang, J.

    2018-01-01

    We investigate the population of high-redshift (3 ≤ z Deep Field-South and 2 Ms Chandra Deep Field-North. Their outstanding sensitivity and spectral characterization of faint sources allow us to focus on the sub-L* regime (logLX ≲ 44), poorly sampled by previous works using shallower data, and the obscured population. Taking fully into account the individual photometric-redshift probability distribution functions, the final sample consists of ≈102 X-ray-selected AGN at 3 ≤ z 23 is ∼0.6-0.8, once incompleteness effects are taken into account, with no strong dependence on redshift or luminosity. We derived the high-redshift AGN number counts down to F0.5-2 keV = 7 × 10-18 erg cm-2 s-1, extending previous results to fainter fluxes, especially at z > 4. We put the tightest constraints to date on the low-luminosity end of AGN luminosity function at high redshift. The space density, in particular, declines at z > 3 at all luminosities, with only a marginally steeper slope for low-luminosity AGN. By comparing the evolution of the AGN and galaxy densities, we suggest that such a decline at high luminosities is mainly driven by the underlying galaxy population, while at low luminosities there are hints of an intrinsic evolution of the parameters driving nuclear activity. Also, the black hole accretion rate density and star formation rate density, which are usually found to evolve similarly at z ≲ 3, appear to diverge at higher redshifts.

  15. The Effects of Age, Refractive Status, and Luminance on Pupil Size

    OpenAIRE

    Guillon, Michel; Dumbleton, Kathryn; Theodoratos, Panagiotis; Gobbe, Marine; Wooley, C. Benjamin; Moody, Kurt

    2016-01-01

    ABSTRACT Purpose Pupil size is critical for optimal performance of presbyopic contact lenses. Although the effect of luminance is well known, little information is available regarding other contributing factors such as aging and refractive status. Methods The cohort population comprised 304 patients (127 male, 177 female) aged 18 to 78 years. Pupils were photographed at three controlled luminance levels 250, 50, and 2.5 cd/m2 using an infra-red macro video camera. Measurements of pupil diamet...

  16. CHARACTERIZATION OF THE MOST LUMINOUS STAR IN M33: A SUPER SYMBIOTIC BINARY

    Energy Technology Data Exchange (ETDEWEB)

    Mikołajewska, Joanna; Iłkiewicz, Krystian [N. Copernicus Astronomical Center, Bartycka 18, PL 00-716 Warsaw (Poland); Caldwell, Nelson [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Shara, Michael M., E-mail: mikolaj@camk.edu.pl [Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States)

    2015-01-30

    We present the first spectrum of the most luminous infrared star in M33, and use it to demonstrate that the object is almost certainly a binary composed of a massive O star and a dust-enshrouded red hypergiant. This is the most luminous symbiotic binary ever discovered. Its radial velocity is an excellent match to that of the hydrogen gas in the disk of M33, supporting our interpretation that it is a very young and massive binary star.

  17. 78 FR 70964 - Luminant Generation Company, LLC

    Science.gov (United States)

    2013-11-27

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Luminant Generation Company, LLC AGENCY: Nuclear Regulatory Commission. ACTION: Combined license... for four consecutive weeks of a combined license (COL) application from Luminant Generation Company...

  18. Dynamics of adaptation at high luminances : Adaptation is faster after luminance decrements than after luminance increments

    NARCIS (Netherlands)

    Poot, L.; Snippe, H.P.; Hateren, J.H. van

    As is well known, dark adaption in the human visual system is much slower than is recovery from darkness. We show that at high photopic luminances the situation is exactly opposite. First, we study detection thresholds for a small light flash, at various delays from decrement and increment steps in

  19. TESTING THE UNIVERSALITY OF THE FUNDAMENTAL METALLICITY RELATION AT HIGH REDSHIFT USING LOW-MASS GRAVITATIONALLY LENSED GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Belli, Sirio; Ellis, Richard S. [Department of Astronomy, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Jones, Tucker [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Richard, Johan [Centre de Recherche Astrophysique de Lyon, Universite Lyon 1, 9 Avenue Charles Andre, F-69561 Saint Genis Laval Cedex (France)

    2013-08-01

    We present rest-frame optical spectra for a sample of nine low-mass star-forming galaxies in the redshift range 1.5 < z < 3 which are gravitationally lensed by foreground clusters. We used Triplespec, an echelle spectrograph at the Palomar 200 inch telescope that is very effective for this purpose as it samples the entire near-infrared spectrum simultaneously. By measuring the flux of nebular emission lines, we derive gas-phase metallicities and star formation rates, and by fitting the optical to infrared spectral energy distributions we obtain stellar masses. Taking advantage of the high magnification due to strong lensing, we are able to probe the physical properties of galaxies with stellar masses in the range 7.8 < log M/M{sub Sun} < 9.4 whose star formation rates are similar to those of typical star-forming galaxies in the local universe. We compare our results with the locally determined relation between stellar mass, gas metallicity, and star formation rate. Our data are in excellent agreement with this relation, with an average offset ({Delta}log (O/H)) = 0.01 {+-} 0.08, suggesting a universal relationship. Remarkably, the scatter around the fundamental metallicity relation is only 0.24 dex, smaller than that observed locally at the same stellar masses, which may provide an important additional constraint for galaxy evolution models.

  20. X-ray Investigations of Quasars with XMM-Newton: Outflow Energetics and High- Redshift Intrinsic Absorption

    Science.gov (United States)

    Brandt, William

    Active Galactic Nuclei (AGNs) are among the most extreme physical environments in the Universe, and it now appears that feedback from AGN winds and jets plays a critical role in the evolution of typical massive galaxies and larger-scale structures. This proposal requests funding to support work on two XMM-Newton guest investigator projects that have already won competitive observing time to study quasars, the most luminous examples of AGNs. The first project is an approved XMM-Newton Large Program that won 350 ks of priority A observation time in AO-9. This project involves an ambitious long-look observation that will obtain the first high-quality grating spectroscopy of a mini-Broad Absorption Line (mini-BAL) quasar, with the aim of assessing the kinetic luminosity of its outflow (the target is PG 1114+445). Grating spectroscopy of a small sample of local Seyfert galaxies has led to highly regarded accurate determinations of their wind properties. The planned extension of grating spectroscopy to the first mini-BAL quasar level AGN will determine if the outflow becomes as powerful as proposed in current AGN feedback scenarios. The 375,000 count EPIC CCD spectra from this long-look will enable unprecedented complementary studies of high-energy absorption features and iron K emission. The data for this project will be gathered over the coming year starting in 2010 May. The second project is an investigation of X-ray absorption in the most-distant radio-loud quasars. Here we are extending our systematic X-ray studies of the most-distant known quasars with XMM-Newton spectroscopy of typical radio-loud quasars (RLQs) at z ~ 4- 5. Our targets are more representative of the overall RLQ population than the small number of highly radio-loud blazars studied at these redshifts. We will search for X-ray absorption in the quasars' environments to determine if it is common among typical RLQs at the highest redshifts. We will also measure X-ray continuum shapes and search for

  1. Detecting Exomoons Around Self-Luminous Giant Exoplanets Through Polarization

    Science.gov (United States)

    Sengupta, Sujan; Marley, Mark Scott

    2016-01-01

    Many of the directly imaged self-luminous gas giant exoplanets have been found to have cloudy atmo- spheres. Scattering of the emergent thermal radiation from these planets by the dust grains in their atmospheres should locally give rise to significant linear polarization of the emitted radiation. However, the observable disk averaged polarization should be zero if the planet is spherically symmetric. Rotation-induced oblateness may yield a net non-zero disk averaged polarization if the planets have sufficiently high spin rotation velocity. On the other hand, when a large natural satellite or exomoon transits a planet with cloudy atmosphere along the line of sight, the asymmetry induced during the transit should give rise to a net non-zero, time resolved linear polarization signal. The peak amplitude of such time dependent polarization may be detectable even for slowly rotating exoplanets. Therefore, we suggest that large exomoons around directly imaged self-luminous exoplanets may be detectable through time resolved imaging polarimetry. Adopting detailed atmospheric models for several values of effective temperature and surface gravity which are appropriate for self-luminous exoplanets, we present the polarization profiles of these objects in the infrared during transit phase and estimate the peak amplitude of polarization that occurs during the the inner contacts of the transit ingress/egress phase. The peak polarization is predicted to range between 0.1 and 0.3 % in the infrared.

  2. Comparison of clinical outcomes between luminal invasive ductal carcinoma and luminal invasive lobular carcinoma.

    Science.gov (United States)

    Adachi, Yayoi; Ishiguro, Junko; Kotani, Haruru; Hisada, Tomoka; Ichikawa, Mari; Gondo, Naomi; Yoshimura, Akiyo; Kondo, Naoto; Hattori, Masaya; Sawaki, Masataka; Fujita, Takashi; Kikumori, Toyone; Yatabe, Yasushi; Kodera, Yasuhiro; Iwata, Hiroji

    2016-03-25

    The pathological and clinical features of invasive lobular carcinoma (ILC) differ from those of invasive ductal carcinoma (IDC). Several studies have indicated that patients with ILC have a better prognosis than those with ductal carcinoma. However, no previous study has considered the molecular subtypes and histological subtypes of ILC. We compared prognosis between IDC and classical, luminal type ILC and developed prognostic factors for early breast cancer patients with classical luminal ILC. Four thousand one hundred ten breast cancer patients were treated at the Aichi Cancer Center Hospital from 2003 to 2012. We identified 1,661 cases with luminal IDC and 105 cases with luminal classical ILC. We examined baseline characteristics, clinical outcomes, and prognostic factors of luminal ILC. The prognosis of luminal ILC was significantly worse than that of luminal IDC. The rates of 5-year disease free survival (DFS) were 91.9% and 88.4% for patients with luminal IDC and luminal ILC, respectively (P = 0.008). The rates of 5-year overall survival (OS) were 97.6% and 93.1% for patients with luminal IDC and luminal ILC respectively (P = 0.030). Although we analyzed prognosis according to stratification by tumor size, luminal ILC tended to have worse DFS than luminal IDC in the large tumor group. In addition, although our analysis was performed according to matching lymph node status, luminal ILC had a significantly worse DFS and OS than luminal IDC in node-positive patients. Survival curves showed that the prognosis for ILC became worse than IDC over time. Multivariate analysis showed that ILC was an important factor related to higher risk of recurrence of luminal type breast cancer, even when tumor size, lymph node status and histological grade were considered. Luminal ILC had worse outcomes than luminal IDC. Consequently, different treatment approaches should be used for luminal ILC than for luminal IDC.

  3. X-Ray Temperatures for the Extended Medium-Sensitivity Survey High-Redshift Cluster Sample: Constraints on Cosmology and the Dark Energy Equation of State

    Science.gov (United States)

    Henry, J. Patrick

    2004-07-01

    We measure the X-ray temperature (and luminosity) with ASCA of all but one cluster in the Einstein Extended Medium-Sensitivity Survey (EMSS) high-redshift (z>=0.3) sample. We compare these data to a complete sample of low-redshift clusters that also has temperature measurements, thereby providing cosmological constraints. Improvements over our previous work include (1) an enlarged high-redshift sample; (2) temperatures for the low-redshift comparison sample that come from the same instrument as the high-redshift sample; (3) the elimination of three EMSS clusters with the same redshift as the target (i.e., not truly serendipitous) and a fourth with an ASCA flux well below the completeness limit; (4) using a theoretical cluster mass function that more closely matches N-body simulations (the Sheth-Torman function); (5) using a cold dark matter power spectrum instead of a power law; (6) using a general cosmology with arbitrary matter density and cosmological constant; (7) using a cosmology that generalizes the cosmological constant to quintessence; (8) including the effects of temperature measurement errors and scatter in the cluster luminosity-temperature relation; and (9) marginalizing over the poorly known normalization of the mass-temperature relation. We find an allowed band in the Ωm0-ΩΛ0 plane of different orientation to the band of constraints provided by the supernovae Ia Hubble diagram and the cosmic microwave background fluctuations. All three bands intersect at the same place: Ωm0~0.3, ΩΛ0~0.7. We measure the quintessence equation-of-state parameter to be w=-(0.42+/-0.21) (68% confidence for one interesting parameter), consistent with previously determined upper limits. We measure the normalization of the mass fluctuation power spectrum to be σ8=0.66+/-0.16 (68% confidence for three interesting parameters). Systematic errors are larger than the statistical errors only for σ8 with our sample; thus the errors for it depend on the details of the

  4. Combining Dark Energy Survey Science Verification data with near-infrared data from the ESO VISTA Hemisphere Survey

    Energy Technology Data Exchange (ETDEWEB)

    Banerji, M.; Jouvel, S.; Lin, H.; McMahon, R. G.; Lahav, O.; Castander, F. J.; Abdalla, F. B.; Bertin, E.; Bosman, S. E.; Carnero, A.; Kind, M. C.; da Costa, L. N.; Gerdes, D.; Gschwend, J.; Lima, M.; Maia, M. A. G.; Merson, A.; Miller, C.; Ogando, R.; Pellegrini, P.; Reed, S.; Saglia, R.; Sanchez, C.; Allam, S.; Annis, J.; Bernstein, G.; Bernstein, J.; Bernstein, R.; Capozzi, D.; Childress, M.; Cunha, C. E.; Davis, T. M.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Doel, P.; Findlay, J.; Finley, D. A.; Flaugher, B.; Frieman, J.; Gaztanaga, E.; Glazebrook, K.; Gonzalez-Fernandez, C.; Gonzalez-Solares, E.; Honscheid, K.; Irwin, M. J.; Jarvis, M. J.; Kim, A.; Koposov, S.; Kuehn, K.; Kupcu-Yoldas, A.; Lagattuta, D.; Lewis, J. R.; Lidman, C.; Makler, M.; Marriner, J.; Marshall, J. L.; Miquel, R.; Mohr, J. J.; Neilsen, E.; Peoples, J.; Sako, M.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla, I.; Sharp, R.; Soares-Santos, M.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Tucker, D.; Uddin, S. A.; Wechsler, R.; Wester, W.; Yuan, F.; Zuntz, J.

    2014-11-25

    We present the combination of optical data from the Science Verification phase of the Dark Energy Survey (DES) with near-infrared (NIR) data from the European Southern Observatory VISTA Hemisphere Survey (VHS). The deep optical detections from DES are used to extract fluxes and associated errors from the shallower VHS data. Joint seven-band (grizYJK) photometric catalogues are produced in a single 3 sq-deg dedicated camera field centred at 02h26m-04d36m where the availability of ancillary multiwavelength photometry and spectroscopy allows us to test the data quality. Dual photometry increases the number of DES galaxies with measured VHS fluxes by a factor of similar to 4.5 relative to a simple catalogue level matching and results in a similar to 1.5 mag increase in the 80 per cent completeness limit of the NIR data. Almost 70 per cent of DES sources have useful NIR flux measurements in this initial catalogue. Photometric redshifts are estimated for a subset of galaxies with spectroscopic redshifts and initial results, although currently limited by small number statistics, indicate that the VHS data can help reduce the photometric redshift scatter at both z < 0.5 and z > 1. We present example DES VHS colour selection criteria for high-redshift luminous red galaxies (LRGs) at z similar to 0.7 as well as luminous quasars. Using spectroscopic observations in this field we show that the additional VHS fluxes enable a cleaner selection of both populations with <10 per cent contamination from galactic stars in the case of spectroscopically confirmed quasars and <0.5 per cent contamination from galactic stars in the case of spectroscopically confirmed LRGs. The combined DES+VHS data set, which will eventually cover almost 5000 sq-deg, will therefore enable a range of new science and be ideally suited for target selection for future wide-field spectroscopic surveys.

  5. The Taiwan ECDFS Near-Infrared Survey: Very Bright End of the Luminosity Function at z > 7

    Science.gov (United States)

    Hsieh, Bau-Ching; Wang, Wei-Hao; Yan, Haojing; Lin, Lihwai; Karoji, Hiroshi; Lim, Jeremy; Ho, Paul T. P.; Tsai, Chao-Wei

    2012-04-01

    The primary goal of the Taiwan ECDFS Near-Infrared Survey (TENIS) is to find well-screened galaxy candidates at z > 7 (z' dropout) in the Extended Chandra Deep Field-South (ECDFS). To this end, TENIS provides relatively deep J and Ks data (~25.3 ABmag, 5σ) for an area of 0.5 × 0.5 deg. Leveraged with existing data at mid-infrared to optical wavelengths, this allows us to screen for the most luminous high-z objects, which are rare and thus require a survey over a large field to be found. We introduce new color selection criteria to select a z > 7 sample with minimal contaminations from low-z galaxies and Galactic cool stars; to reduce confusion in the relatively low angular resolution Infrared Array Camera (IRAC) images, we introduce a novel deconvolution method to measure the IRAC fluxes of individual sources. Illustrating perhaps the effectiveness at which we screen out interlopers, we find only one z > 7 candidate, TENIS-ZD1. The candidate has a weighted z phot of 7.8, and its colors and luminosity indicate a young (45M years old) starburst galaxy with a stellar mass of 3.2 × 1010 M ⊙. The result matches with the observational luminosity function analysis and the semianalytic simulation result based on the Millennium Simulations, which may over predict the volume density for high-z massive galaxies. The existence of TENIS-ZD1, if confirmed spectroscopically to be at z > 7, therefore poses a challenge to current theoretical models for how so much mass can accumulate in a galaxy at such a high redshift.

  6. THE TAIWAN ECDFS NEAR-INFRARED SURVEY: VERY BRIGHT END OF THE LUMINOSITY FUNCTION AT z > 7

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Bau-Ching; Wang, Wei-Hao; Lin, Lihwai; Lim, Jeremy; Ho, Paul T. P. [Institute of Astrophysics and Astronomy, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Yan, Haojing [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); Karoji, Hiroshi [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Tsai, Chao-Wei [Infrared Processing and Analysis Center, California Institute of Technology, 770 South Wilson Avenue, Pasadena, CA 91125 (United States)

    2012-04-10

    The primary goal of the Taiwan ECDFS Near-Infrared Survey (TENIS) is to find well-screened galaxy candidates at z > 7 (z' dropout) in the Extended Chandra Deep Field-South (ECDFS). To this end, TENIS provides relatively deep J and K{sub s} data ({approx}25.3 ABmag, 5{sigma}) for an area of 0.5 Multiplication-Sign 0.5 deg. Leveraged with existing data at mid-infrared to optical wavelengths, this allows us to screen for the most luminous high-z objects, which are rare and thus require a survey over a large field to be found. We introduce new color selection criteria to select a z > 7 sample with minimal contaminations from low-z galaxies and Galactic cool stars; to reduce confusion in the relatively low angular resolution Infrared Array Camera (IRAC) images, we introduce a novel deconvolution method to measure the IRAC fluxes of individual sources. Illustrating perhaps the effectiveness at which we screen out interlopers, we find only one z > 7 candidate, TENIS-ZD1. The candidate has a weighted z{sub phot} of 7.8, and its colors and luminosity indicate a young (45M years old) starburst galaxy with a stellar mass of 3.2 Multiplication-Sign 10{sup 10} M{sub Sun }. The result matches with the observational luminosity function analysis and the semianalytic simulation result based on the Millennium Simulations, which may over predict the volume density for high-z massive galaxies. The existence of TENIS-ZD1, if confirmed spectroscopically to be at z > 7, therefore poses a challenge to current theoretical models for how so much mass can accumulate in a galaxy at such a high redshift.

  7. The luminous and the grey

    CERN Document Server

    Batchelor, David

    2014-01-01

    Color surrounds us: the lush green hues of trees and grasses, the variant blues of water and the sky, the bright pops of yellow and red from flowers. But at the same time, color lies at the limits of language and understanding. In this absorbing sequel to Chromophobia-which addresses the extremes of love and loathing provoked by color since antiquity-David Batchelor charts color's more ambiguous terrain.   The Luminous and the Grey explores the places where color comes into being and where it fades away, probing when it begins and when it ends both in the imagination and in the material world.

  8. The Effects of Age, Refractive Status, and Luminance on Pupil Size.

    Science.gov (United States)

    Guillon, Michel; Dumbleton, Kathryn; Theodoratos, Panagiotis; Gobbe, Marine; Wooley, C Benjamin; Moody, Kurt

    2016-09-01

    Pupil size is critical for optimal performance of presbyopic contact lenses. Although the effect of luminance is well known, little information is available regarding other contributing factors such as aging and refractive status. The cohort population comprised 304 patients (127 male, 177 female) aged 18 to 78 years. Pupils were photographed at three controlled luminance levels 250, 50, and 2.5 cd/m using an infra-red macro video camera. Measurements of pupil diameter were conducted after transforming pixel values to linear values in millimeters. Luminance was the most influential factor with pupil diameter increasing with decreased luminance (p Pupil diameter decreased significantly with increasing age, the effect being most marked at low luminance (pupil diameters were measured for hyperopes and the largest for myopes and although refractive error was not a significant factor alone, there was a significant interaction between luminance and refractive error with the greatest differences in pupil diameter between myopes and emmetropes at low luminance (p Pupil diameter changes modeled by multilinear regression (p pupil diameter. Both age and refractive status were found to affect pupil size with larger pupils measured for younger patients and myopes. Designs for multifocal contact lens corrections should take both age and refractive status into consideration; a faster progression from distance to near corrections across the optical zone of the lens is expected to be required for established presbyopes and hyperopes than it is for early presbyopes, myopes, and emmetropes.

  9. Effect of primordial non-Gaussianities on the far-UV luminosity function of high-redshift galaxies: implications for cosmic reionization

    Science.gov (United States)

    Chevallard, Jacopo; Silk, Joseph; Nishimichi, Takahiro; Habouzit, Melanie; Mamon, Gary A.; Peirani, Sébastien

    2015-01-01

    Understanding how the intergalactic medium (IGM) was reionized at z ≳ 6 is one of the big challenges of current high-redshift astronomy. It requires modelling the collapse of the first astrophysical objects (Pop III stars, first galaxies) and their interaction with the IGM, while at the same time pushing current observational facilities to their limits. The observational and theoretical progress of the last few years have led to the emergence of a coherent picture in which the budget of hydrogen-ionizing photons is dominated by low-mass star-forming galaxies, with little contribution from Pop III stars and quasars. The reionization history of the Universe therefore critically depends on the number density of low-mass galaxies at high redshift. In this work, we explore how changes in the cosmological model, and in particular in the statistical properties of initial density fluctuations, affect the formation of early galaxies. Following Habouzit et al. (2014), we run five different N-body simulations with Gaussian and (scale-dependent) non-Gaussian initial conditions, all consistent with Planck constraints. By appealing to a phenomenological galaxy formation model and to a population synthesis code, we compute the far-UV galaxy luminosity function down to MFUV = -14 at redshift 7 ≤ z ≤ 15. We find that models with strong primordial non-Gaussianities on ≲ Mpc scales show a far-UV luminosity function significantly enhanced (up to a factor of 3 at z = 14) in low-mass galaxies. We adopt a reionization model calibrated from state-of-the-art hydrodynamical simulations and show that such scale-dependent non-Gaussianities leave a clear imprint on the Universe reionization history and electron Thomson scattering optical depth τe. Although current uncertainties in the physics of reionization and on the determination of τe still dominate the signatures of non-Gaussianities, our results suggest that τe could ultimately be used to constrain the statistical properties

  10. Luminance Analysis of Linear Fluorescent Lamp

    OpenAIRE

    Štěpánek, J.

    2015-01-01

    My paper deals with theme of luminance analysis. The aim of the paper is to find out how change luminance of linear fluorescent lamps with the change of light source position. Linear fluorescent lamp will be measured in horizontal position and in vertical position. Digital camera will be used for measurement. Paper is divided into theoretical part and into practical part.

  11. Lightness constancy through a veiling luminance.

    Science.gov (United States)

    Gilchrist, A L; Jacobsen, A

    1983-12-01

    Observers were asked to select samples from a Munsell chart to match the lightness of seven identified surfaces in an outdoor scene they were shown. A separate group that was given the same task but viewed the same scene covered with a veiling luminance equal in intensity to the highest luminance in the scene selected almost the same matches. The same lightness constancy results were obtained using an abstract laboratory display to rule out memory color. These results challenge ratio and contrast theories because a veiling luminance, by adding a constant luminance to every poing in the image, dramatically alters luminance ratios. Lightness constancy was not obtained, however, when these three-dimensional real-world-type displays were replaced by a flat, Mondrian-type display consisting of surface grays from white to black, whether or not colored regions were present in the display; lightness matches were consistent with ratio predictions both with and without the veil.

  12. Red galaxies at high redshift

    NARCIS (Netherlands)

    Wuyts, Stijn Elisabeth Raphaël

    2007-01-01

    From its origin at the center of a star to the edge, through the surrounding gas and dust in the distant galaxy, through the intergalactic medium, traveling billions of light years only to be reflected by a mirror and captured by a detector; the little amount of light observed from galaxies in the

  13. Maximum Spectral Luminous Efficacy of White Light

    OpenAIRE

    Murphy Jr., T. W.

    2013-01-01

    As lighting efficiency improves, it is useful to understand the theoretical limits to luminous efficacy for light that we perceive as white. Independent of the efficiency with which photons are generated, there exists a spectrally-imposed limit to the luminous efficacy of any source of photons. We find that, depending on the acceptable bandpass and---to a lesser extent---the color temperature of the light, the ideal white light source achieves a spectral luminous efficacy of 250--370 lm/W. Th...

  14. Optical coherence tomography investigations of ceramic lumineers

    Science.gov (United States)

    Fernandes, Luana O.; Graça, Natalia D. R. L.; Melo, Luciana S. A.; Silva, Claudio H. V.; Gomes, Anderson S. L.

    2016-02-01

    Lumineers are veneer laminates used as an alternative for aesthetic dental solutions of the highest quality, but the only current means of its performance assessment is visual inspection. The objective of this study was to use the Optical Coherence Tomography (OCT) technique working in spectral domain to analyze in vivo in a single patient, 14 lumineers 180 days after cementation. It was possible to observe images in various kinds of changes in the cementing line and the laminate. It was concluded that the OCT is an effective and promising method to clinical evaluation of the cementing line in lumineers.

  15. Maximum Spectral Luminous Efficacy of White Light

    CERN Document Server

    Murphy, T W

    2013-01-01

    As lighting efficiency improves, it is useful to understand the theoretical limits to luminous efficacy for light that we perceive as white. Independent of the efficiency with which photons are generated, there exists a spectrally-imposed limit to the luminous efficacy of any source of photons. We find that, depending on the acceptable bandpass and---to a lesser extent---the color temperature of the light, the ideal white light source achieves a spectral luminous efficacy of 250--370 lm/W. This is consistent with previous calculations, but here we explore the maximum luminous efficacy as a function of photopic sensitivity threshold, color temperature, and color rendering index; deriving peak performance as a function of all three parameters. We also present example experimental spectra from a variety of light sources, quantifying the intrinsic efficacy of their spectral distributions.

  16. Maximum spectral luminous efficacy of white light

    Science.gov (United States)

    Murphy, Thomas W.

    2012-05-01

    As lighting efficiency improves, it is useful to understand the theoretical limits to luminous efficacy for light that we perceive as white. Independent of the efficiency with which photons are generated, there exists a spectrally imposed limit to the luminous efficacy of any source of photons. We find that, depending on the acceptable bandpass and—to a lesser extent—the color temperature of the light, the ideal white light source achieves a spectral luminous efficacy of 250-370 lm/W. This is consistent with previous calculations, but here we explore the maximum luminous efficacy as a function of photopic sensitivity threshold, color temperature, and color rendering index; deriving peak performance as a function of all three parameters. We also present example experimental spectra from a variety of light sources, quantifying the intrinsic efficacy of their spectral distributions.

  17. Daylight calculations using constant luminance curves

    Energy Technology Data Exchange (ETDEWEB)

    Betman, E. [CRICYT, Mendoza (Argentina). Laboratorio de Ambiente Humano y Vivienda

    2005-02-01

    This paper presents a simple method to manually estimate daylight availability and to make daylight calculations using constant luminance curves calculated with local illuminance and irradiance data and the all-weather model for sky luminance distribution developed in the Atmospheric Science Research Center of the University of New York (ARSC) by Richard Perez et al. Work with constant luminance curves has the advantage that daylight calculations include the problem's directionality and preserve the information of the luminous climate of the place. This permits accurate knowledge of the resource and a strong basis to establish conclusions concerning topics related to the energy efficiency and comfort in buildings. The characteristics of the proposed method are compared with the method that uses the daylight factor. (author)

  18. RadioAstron space VLBI imaging of polarized radio emission in the high-redshift quasar 0642+449 at 1.6 GHz

    Science.gov (United States)

    Lobanov, A. P.; Gómez, J. L.; Bruni, G.; Kovalev, Y. Y.; Anderson, J.; Bach, U.; Kraus, A.; Zensus, J. A.; Lisakov, M. M.; Sokolovsky, K. V.; Voytsik, P. A.

    2015-11-01

    Context. Polarization of radio emission in extragalactic jets at a sub-milliarcsecond angular resolution holds important clues for understanding the structure of the magnetic field in the inner regions of the jets and in close vicinity of the supermassive black holes in the centers of active galaxies. Aims: Space VLBI observations provide a unique tool for polarimetric imaging at a sub-milliarcsecond angular resolution and studying the properties of magnetic field in active galactic nuclei on scales of less than 104 gravitational radii. Methods: A space VLBI observation of high-redshift quasar TXS 0642+449 (OH 471), made at a wavelength of 18 cm (frequency of 1.6 GHz) as part of the early science programme (ESP) of the RadioAstron mission, is used here to test the polarimetric performance of the orbiting Space Radio Telescope (SRT) employed by the mission, to establish a methodology for making full Stokes polarimetry with space VLBI at 1.6 GHz, and to study the polarized emission in the target object on sub-milliarcsecond scales. Results: Polarization leakage of the SRT at 18 cm is found to be within 9% in amplitude, demonstrating the feasibility of high fidelity polarization imaging with RadioAstron at this wavelength. A polarimetric image of 0642+449 with a resolution of 0.8 mas (signifying an ~4 times improvement over ground VLBI observations at the same wavelength) is obtained. The image shows a compact core-jet structure with low (≈2%) polarization and predominantly transverse magnetic field in the nuclear region. The VLBI data also uncover a complex structure of the nuclear region, with two prominent features possibly corresponding to the jet base and a strong recollimation shock. The maximum brightness temperature at the jet base can be as high as 4 × 1013 K.

  19. Cluster Mass Calibration at High Redshift: HST Weak Lensing Analysis of 13 Distant Galaxy Clusters from the South Pole Telescope Sunyaev-Zel'dovich Survey

    Energy Technology Data Exchange (ETDEWEB)

    Schrabback, T.; et al.

    2016-11-11

    We present an HST/ACS weak gravitational lensing analysis of 13 massive high-redshift (z_median=0.88) galaxy clusters discovered in the South Pole Telescope (SPT) Sunyaev-Zel'dovich Survey. This study is part of a larger campaign that aims to robustly calibrate mass-observable scaling relations over a wide range in redshift to enable improved cosmological constraints from the SPT cluster sample. We introduce new strategies to ensure that systematics in the lensing analysis do not degrade constraints on cluster scaling relations significantly. First, we efficiently remove cluster members from the source sample by selecting very blue galaxies in V-I colour. Our estimate of the source redshift distribution is based on CANDELS data, where we carefully mimic the source selection criteria of the cluster fields. We apply a statistical correction for systematic photometric redshift errors as derived from Hubble Ultra Deep Field data and verified through spatial cross-correlations. We account for the impact of lensing magnification on the source redshift distribution, finding that this is particularly relevant for shallower surveys. Finally, we account for biases in the mass modelling caused by miscentring and uncertainties in the mass-concentration relation using simulations. In combination with temperature estimates from Chandra we constrain the normalisation of the mass-temperature scaling relation ln(E(z) M_500c/10^14 M_sun)=A+1.5 ln(kT/7.2keV) to A=1.81^{+0.24}_{-0.14}(stat.) +/- 0.09(sys.), consistent with self-similar redshift evolution when compared to lower redshift samples. Additionally, the lensing data constrain the average concentration of the clusters to c_200c=5.6^{+3.7}_{-1.8}.

  20. Multi-Epoch Photometry of Luminous Stars in M31 and M33

    Science.gov (United States)

    Martin, John C.; Humphreys, Roberta M.

    2017-06-01

    Typically, the characteristics of supernovae and supernovae impostor progenitors are pieced together post-hoc from disparate sources after the event. Regular monitoring of luminous stars in nearby galaxies provides a more detailed and uniform source of information about those stars leading up to a significant event.We present Johnson/Cousins BVRI photometry from the first four years (2012 - 2016) of a targeted ground-based monitoring campaign of luminous stars in M31 and M33 including: likely supernovae and supernovae impostor progenitors, luminous infrared sources, classical LBVs, and warm and cool hypergiants. We have constructed a pipeline capable of quickly mining our images for photometry of additional targets.The survey will continue to image most of M31 and M33 on an annual basis for the foreseeable future.

  1. Study on the Influence Factors of the Luminous Intensity of the Long Afterglow Luminous Paints

    Directory of Open Access Journals (Sweden)

    Zhao Su

    2016-01-01

    Full Text Available In order to extend the time afterglow luminous powder, enhancement the brightness of luminous paint, this study explore affect long afterglow energy storage luminous paints brightness of the main factors. Luminous paints were prepared with rare earth aluminate long afterglow luminescent powder, first is luminous powder surface modification, then investigate the influence of light emitting powder content, calcium carbonate, titanium dioxide, nano alumina and other fillers on the luminescent properties of the paints. It was concluded that the water resistance of the luminescent powder is better and the brightness can be improved after the modification of anhydrous alcohol. The addition of nano-alumina can improve the brightness of the system, and can effectively enhance the hardness of the paints. In the paints, the two kinds of components of carbonate and titanium dioxide have little effect on the luminescent brightness of the painting.

  2. Searching for luminous absorbed sources in the WISE AGN catalogue

    Science.gov (United States)

    Mountrichas, G.; Georgantopoulos, I.; Secrest, N. J.; Ordovás-Pascual, I.; Corral, A.; Akylas, A.; Mateos, S.; Carrera, F. J.; Batziou, E.

    2017-07-01

    Mid-infrared (IR) colour selection techniques have proved to be very efficient in finding active galactic nuclei (AGN). This is because the AGN heats the surrounding dust producing warm mid-IR colours. Using the Wide-field Infrared Survey Explorer 3.6, 4.5 and 12 μm colours, the largest sample of IR selected AGN has already been produced containing 1.4 million AGN over the whole sky. Here, we explore the X-ray properties of this AGN sample by cross-correlating it with the subsample of the 3XMM X-ray catalogue that has available X-ray spectra and at the same time optical spectroscopy from Sloan Digital Sky Survey (SDSS). Our goal is to find rare luminous obscured AGN. Our final sample contains 65 QSOs with log νLν ≥ 46.2 erg s-1. This IR luminosity cut corresponds to log LX ≈ 45 erg s-1, at the median redshift of our sample (z = 2.3), that lies at the bright end of the X-ray luminosity function at z > 2. The X-ray spectroscopic analysis reveals seven obscured AGN having a column density NH > 1022 cm-2. Six of them show evidence for broad [C IV] absorption lines and five are classified as broad absorption line QSOs. We fit the optical spectra of our X-ray absorbed sources to estimate the optical reddening. We find that none of these show any obscuration according to the optical continuum. These sources add to the growing evidence for populations of luminous QSOs with evidence for substantial absorption by outflowing ionized material, similar to those expected to be emerging from their absorbing cocoons in the framework of AGN/galaxy co-evolution.

  3. The Role of the Most Luminous Obscured AGNs in Galaxy Assembly at z ∼ 2

    Energy Technology Data Exchange (ETDEWEB)

    Farrah, Duncan [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Petty, Sara [Green Science Policy Institute, Berkeley, CA 94709 (United States); Connolly, Brian [Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229 (United States); Blain, Andrew [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Efstathiou, Andreas [School of Sciences, European University Cyprus, Diogenes Street, Engomi, 1516 Nicosia (Cyprus); Lacy, Mark [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Stern, Daniel; Bridge, Carrie; Eisenhardt, Peter; Moustakas, Leonidas [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Lake, Sean; Tsai, Chao-Wei [Physics and Astronomy Department, University of California, Los Angeles, CA 90095 (United States); Jarrett, Tom [Department of Astronomy, University of Cape Town, 7700 Rondebosch, Capetown 7700 (South Africa); Benford, Dominic [Observational Cosmology Lab., Code 665, NASA at Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Jones, Suzy [Department of Space, Earth, and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala (Sweden); Assef, Roberto [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago (Chile); Wu, Jingwen [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing, 100012 (China)

    2017-08-01

    We present Hubble Space Telescope WFC3 F160W imaging and infrared spectral energy distributions for 12 extremely luminous, obscured active galactic nuclei (AGNs) at 1.8 < z < 2.7 selected via “hot, dust-obscured” mid-infrared colors. Their infrared luminosities span (2–15) × 10{sup 13} L {sub ⊙}, making them among the most luminous objects in the universe at z ∼ 2. In all cases, the infrared emission is consistent with arising at least for the most part from AGN activity. The AGN fractional luminosities are higher than those in either submillimeter galaxies or AGNs selected via other mid-infrared criteria. Adopting the G , M {sub 20}, and A morphological parameters, together with traditional classification boundaries, infers that three-quarters of the sample are mergers. Our sample does not, however, show any correlation between the considered morphological parameters and either infrared luminosity or AGN fractional luminosity. Moreover, the asymmetries and effective radii of our sample are distributed identically to those of massive galaxies at z ∼ 2. We conclude that our sample is not preferentially associated with mergers, though a significant merger fraction is still plausible. Instead, we propose that our sample includes examples of the massive galaxy population at z ∼ 2 that harbor a briefly luminous, “flickering” AGN and in which the G and M {sub 20} values have been perturbed due to either the AGN and/or the earliest formation stages of a bulge in an inside-out manner. Furthermore, we find that the mass assembly of the central black holes in our sample leads the mass assembly of any bulge component. Finally, we speculate that our sample represents a small fraction of the immediate antecedents of compact star-forming galaxies at z ∼ 2.

  4. Dust composition and mass-loss return from the luminous blue variable R71 in the LMC

    NARCIS (Netherlands)

    Guha Niyogi, S.; Min, M.; Meixner, M.; Waters, L.B.F.M.; Seale, J.; Tielens, A.G.G.M.

    2014-01-01

    Context. We present an analysis of mid- and far-infrared (IR) spectrum and spectral energy distribution (SED) of the luminous blue variable (LBV) R71 in the Large Magellanic Cloud (LMC). Aims. This work aims to understand the overall contribution of high-mass LBVs to the total dust-mass budget of

  5. Evidence for Infrared-faint Radio Sources as z > 1 Radio-loud Active Galactic Nuclei

    Science.gov (United States)

    Huynh, Minh T.; Norris, Ray P.; Siana, Brian; Middelberg, Enno

    2010-02-01

    Infrared-Faint Radio Sources (IFRSs) are a class of radio objects found in the Australia Telescope Large Area Survey which have no observable mid-infrared counterpart in the Spitzer Wide-area Infrared Extragalactic (SWIRE) survey. The extended Chandra Deep Field South now has even deeper Spitzer imaging (3.6-70 μm) from a number of Legacy surveys. We report the detections of two IFRS sources in IRAC images. The non-detection of two other IFRSs allows us to constrain the source type. Detailed modeling of the spectral energy distribution of these objects shows that they are consistent with high-redshift (z >~ 1) active galactic nuclei.

  6. X-ray Counterparts of Infrared Faint Radio Sources

    Science.gov (United States)

    Schartel, Norbert

    2011-10-01

    Infrared Faint Radio Sources (IFRS) are radio sources with extremely faint or even absent infrared emission in deep Spitzer Surveys. Models of their spectral energy distributions, the ratios of radio to infrared flux densities and their steep radio spectra strongly suggest that IFRS are AGN at high redshifts (2IFRS, but if confirmed, the increased AGN numbers at these redshifts will account for the unresolved part of the X-ray background. The identification of X-ray counterparts of IFRS is considered to be the smoking gun for this hypothesis. We propose to observe 8 IFRS using 30ks pointed observations. X-ray detections of IFRS with different ratios of radio-to-infrared fluxes, will constrain the class-specific SED.

  7. Ultra High Luminance and Luminous Efficacy Mercury-free Flat Fluorescent Lamp

    Science.gov (United States)

    Seo, In Woo; Oh, Byung Joo; Jung, Jae-Chul; Whang, Ki-Woong

    2009-10-01

    We proposed a new Mercury-free Flat Fluorescent Lamp (MFFL) as a flat light source which can be used as an alternative of conventional line-type Cold Cathode Fluorescent Lamp (CCFL) containing Mercury. The MFFL using dielectric barrier discharge with Ne-Xe gas mixtures has a pair of the parallel-running main electrodes covered by dielectric layer in a 40x40 mm size of the emission area as a unit cell. A new electrode structure and optimized driving methods have been adopted to make an effective glow discharge which shows a wide driving voltage margin. In order to realize the high luminance and luminous efficacy MFFLs, we optimized the phosphor profile to enlarge the surface area. The MFFL with the new phosphor profile shows a very wide luminance range from 2,600 to 17,000 nit with the corresponding luminous efficacy from 66 to 32.5 lm/W. The results were obtained with the color coordinate of the phosphor to be around (0.25, 0.23), which is required for LCD backlights. The work to realize improved luminance and luminous efficacy MFFLs with the color coordinate (0.32, 0.32) for daylight lighting is in progress.

  8. Fast-Growing SMBHs in Fast-Growing Galaxies, at High Redshifts: The Role of Major Mergers As Revealed by ALMA

    Directory of Open Access Journals (Sweden)

    Benny Trakhtenbrot

    2017-11-01

    Full Text Available We present a long-term, multi-wavelength project to understand the epoch of fastest growth of the most massive black holes by using a sample of 40 luminous quasars at z ≃ 4.8. These quasars have rather uniform properties, with typical accretion rates and black hole masses of L/LEdd ≃ 0.7 and MBH ≃ 109M⊙. The sample consists of “FIR-bright” sources with a previous Herschel/SPIRE detection, suggesting SFR > 1,000 M⊙ yr−1, as well as of “FIR-faint” sources for which Herschel stacking analysis implies a typical SFR of ~400 M⊙ yr−1. Six of the quasars have been observed by ALMA in [C ii] λ157.74μm line emission and adjacent rest-frame 150μm continuum, to study the dusty cold ISM. ALMA detected companion, spectroscopically confirmed sub-mm galaxies (SMGs for three sources—one FIR-bright and two FIR-faint. The companions are separated by ~14–45 kpc from the quasar hosts, and we interpret them as major galaxy interactions. Our ALMA data therefore clearly support the idea that major mergers may be important drivers for rapid, early SMBH growth. However, the fact that not all high-SFR quasar hosts are accompanied by interacting SMGs, and their ordered gas kinematics observed by ALMA, suggest that other processes may be fueling these systems. Our analysis thus demonstrates the diversity of host galaxy properties and gas accretion mechanisms associated with early and rapid SMBH growth.

  9. Measuring of luminous efficacy of light sources

    OpenAIRE

    Pungert, David

    2016-01-01

    In the theoretical part of my thesis, I present light spectra, luminous efficacy, as well as light sources and sensors used in my experimental work. In the experimental part of the thesis, I compare three sensors: a spectrometer measuring the light spectrum, a luxmeter measuring the light intensity, as perceived by the human eye, and a light meter measuring the light intensity in watts per square meter. To compare the sensors, I find the relation between the quantities they measure. With cali...

  10. The EXIST Infra-Red Telescope System: Design and Performance

    Science.gov (United States)

    Moseley, Harvey; Golisano, C.; Gong, Q.; Allen, B.; Grindlay, J.; Hong, J.; Kutyrev, A.; Woodgate, B.; EXIST Team

    2010-01-01

    The Infra-Red Telescope is a critical element of the EXIST (Energetic X-Ray Imaging Survey Telescope) observatory. It is a passively cooled 1.1m visible/infrared telescope. The primary goal of the IRT is to obtain photometric and spectroscopic measurements of high redshift (>6) gamma ray burst afterglows to study the nature of these enigmatic events and the their environments, and to use them as probes of the composition and ionization state of the intergalactiic medium of the young universe . The IRT will provide a prompt follow up (within three minutes) of the transient discovered by the EXIST with exceptional NIR sensitivitiy (AB=24 in 100s) surpassing HST in the infrared due to its passively cooled (-30ºC) mirror. Its optical design and spectral coverage is tailored to the high redshift transient events that require prompt pointing, identification, accurate phototmetry and both low and high resolution spectroscopy. Here we describe the telescope, its instrument complement, and the cooling systems which provide its remarkable sensitivity.

  11. The EXIST Infra-Red Telescope System: Design and Performance

    Science.gov (United States)

    Moseley, Samuel H.

    2010-01-01

    The Infra-Red Telescope is a critical element of the EXIST (Energetic X-Ray Imaging Survey Telescope) observatory. It is a passively cooled 1.lm visible/infrared telescope. The primary goal of the IRT is to obtain photometric and spectroscopic measurements of high redshift (>6) gamma ray burst afterglows to study the nature of these enigmatic events and their environments, and to use them as probes of the composition and ionization state of the intergalactic medium of the young universe. The IRT will provide a prompt follow up (within three minutes) of the transient discovered by the EXIST with exceptional NIR sensitivity (AB=24 in 100s) surpassing HST in the infrared due to its passively cooled (- 30 C) mirror. Its optical design and spectral coverage is tailored to the high redshift transient events that require prompt pointing, identification, accurate photometry and both low and high resolution spectroscopy. Here we describe the telescope, its instrument complement, and the cooling systems which provide its remarkable sensitivity

  12. HiZELS: a high-redshift survey of Hα emitters - I. The cosmic star formation rate and clustering at z = 2.23

    Science.gov (United States)

    Geach, J. E.; Smail, Ian; Best, P. N.; Kurk, J.; Casali, M.; Ivison, R. J.; Coppin, K.

    2008-08-01

    We present results from a near-infrared narrow-band survey of emission-line galaxies at z = 2.23, using the Wide Field Camera on the United Kingdom Infrared Telescope. The H2S1 narrow-band filter (λc = 2.121μm) we employ selects the Hα emission-line redshifted to z = 2.23, and is thus suitable for selecting `typical' star-forming galaxies and active galactic nuclei at this epoch. The pilot study was undertaken in the well-studied Cosmological Evolution Survey field (COSMOS) and is already the largest near-infrared narrow-band survey at this depth, with a line flux limit of FHα ~ 10-16ergs-1cm-2 over 0.60deg2, probing ~220 × 103Mpc3 (comoving) down to a limiting star formation rate of ~30Msolaryr-1 (3σ). In this paper, we present the results from our pilot survey and evaluate the Hα luminosity function and estimate the clustering properties of Hα emitters at z = 2.23 from 55 detected galaxies. The integrated luminosity function is used to estimate the volume-averaged star formation rate at z = 2.23: ρSFR = 0.17+0.16-0.09Msolaryr-1Mpc-3 for LHα > 1042ergs-1. For the first time, we use the Hα star formation tracer to reliably constrain ρSFR out to z = 2.23 demonstrating the rapid increase in ρSFR out to this redshift as well as confirming the flattening in ρSFR between z ~ 1 and 2. In addition to the luminosity distribution, we analyse the clustering properties of these galaxies. Using the two-point angular correlation function, ω(θ), we estimate a real-space correlation length of r0 = 4.2+0.4-0.2h-1Mpc. In comparison to models of clustering which take into account bias evolution, we estimate that these galaxies are hosted by dark matter haloes of mass Mhalo ~ 1012Msolar consistent with the progenitors of the Milky Way. Based on observations obtained with the Wide Field CAMera (WFCAM) on the United Kingdom Infrared Telescope (UKIRT). E-mail: j.e.geach@durham.ac.uk

  13. Compact RGBY light sources with high luminance for laser display applications

    Science.gov (United States)

    Paschke, Katrin; Blume, Gunnar; Werner, Nils; Müller, André; Sumpf, Bernd; Pohl, Johannes; Feise, David; Ressel, Peter; Sahm, Alexander; Bege, Roland; Hofmann, Julian; Jedrzejczyk, Daniel; Tränkle, Günther

    2017-10-01

    Watt-class visible laser light with a high luminance can be created with high-power GaAs-based lasers either directly in the red spectral region or using single-pass second harmonic generation (SHG) for the colors in the blue-yellow spectral region. The concepts and results of red- and near infrared-emitting distributed Bragg reflector tapered lasers and master oscillator power amplifier systems as well as their application for SHG bench-top experiments and miniaturized modules are presented. Examples of these high-luminance light sources aiming at different applications such as flying spot display or holographic 3D cinema are discussed in more detail. The semiconductor material allows an easy adaptation of the wavelength allowing techniques such as six-primary color 3D projection or color space enhancement by adding a fourth yellow color.

  14. The effects of fixation target size and luminance on microsaccades and square-wave jerks

    Directory of Open Access Journals (Sweden)

    Michael B. McCamy

    2013-02-01

    Full Text Available A large amount of classic and contemporary vision studies require subjects to fixate a target. Target fixation serves as a normalizing factor across studies, promoting the field’s ability to compare and contrast experiments. Yet, fixation target parameters, including luminance, contrast, size, shape and color, vary across studies, potentially affecting the interpretation of results. Previous research on the effects of fixation target size and luminance on the control of fixation position rendered conflicting results, and no study has examined the effects of fixation target characteristics on square-wave jerks, the most common type of saccadic intrusion. Here we set out to determine the effects of fixation target size and luminance on the characteristics of microsaccades and square-wave jerks, over a large range of stimulus parameters. Human subjects fixated a circular target with varying luminance and size while we recorded their eye movements with an infrared video tracker (EyeLink 1000, SR Research. We detected microsaccades and SWJs automatically with objective algorithms developed previously. Microsaccade rates decreased linearly and microsaccade magnitudes increased linearly with target size. The percent of microsaccades forming part of SWJs decreased, and the time from the end of the initial SWJ saccade to the beginning of the second SWJ saccade (SWJ inter-saccadic interval; ISI increased with target size. The microsaccadic preference for horizontal direction also decreased moderately with target size . Target luminance did not affect significantly microsaccades or SWJs, however. In the absence of a fixation target, microsaccades became scarcer and larger, while SWJ prevalence decreased and SWJ ISIs increased. Thus, the choice of fixation target can affect experimental outcomes, especially in human factors and in visual and oculomotor studies. These results have implications for previous and future research conducted under fixation

  15. The effects of fixation target size and luminance on microsaccades and square-wave jerks.

    Science.gov (United States)

    McCamy, Michael B; Najafian Jazi, Ali; Otero-Millan, Jorge; Macknik, Stephen L; Martinez-Conde, Susana

    2013-01-01

    A large amount of classic and contemporary vision studies require subjects to fixate a target. Target fixation serves as a normalizing factor across studies, promoting the field's ability to compare and contrast experiments. Yet, fixation target parameters, including luminance, contrast, size, shape and color, vary across studies, potentially affecting the interpretation of results. Previous research on the effects of fixation target size and luminance on the control of fixation position rendered conflicting results, and no study has examined the effects of fixation target characteristics on square-wave jerks, the most common type of saccadic intrusion. Here we set out to determine the effects of fixation target size and luminance on the characteristics of microsaccades and square-wave jerks, over a large range of stimulus parameters. Human subjects fixated a circular target with varying luminance and size while we recorded their eye movements with an infrared video tracker (EyeLink 1000, SR Research). We detected microsaccades and SWJs automatically with objective algorithms developed previously. Microsaccade rates decreased linearly and microsaccade magnitudes increased linearly with target size. The percent of microsaccades forming part of SWJs decreased, and the time from the end of the initial SWJ saccade to the beginning of the second SWJ saccade (SWJ inter-saccadic interval; ISI) increased with target size. The microsaccadic preference for horizontal direction also decreased moderately with target size . Target luminance did not affect significantly microsaccades or SWJs, however. In the absence of a fixation target, microsaccades became scarcer and larger, while SWJ prevalence decreased and SWJ ISIs increased. Thus, the choice of fixation target can affect experimental outcomes, especially in human factors and in visual and oculomotor studies. These results have implications for previous and future research conducted under fixation conditions, and should

  16. Infrared Faint Radio Sources in the Extended Chandra Deep Field South

    Science.gov (United States)

    Huynh, Minh T.

    2009-01-01

    Infrared-Faint Radio Sources (IFRSs) are a class of radio objects found in the Australia Telescope Large Area Survey (ATLAS) which have no observable counterpart in the Spitzer Wide-area Infrared Extragalactic Survey (SWIRE). The extended Chandra Deep Field South now has even deeper Spitzer imaging (3.6 to 70 micron) from a number of Legacy surveys. We report the detections of two IFRS sources in IRAC images. The non-detection of two other IFRSs allows us to constrain the source type. Detailed modeling of the SED of these objects shows that they are consistent with high redshift AGN (z > 2).

  17. NuSTAR AND MULTIFREQUENCY STUDY OF THE TWO HIGH-REDSHIFT BLAZARS S5 0836+710 AND PKS 2149–306

    Energy Technology Data Exchange (ETDEWEB)

    Tagliaferri, G.; Ghisellini, G.; Covino, S.; Sbarrato, T. [INAF—Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy); Perri, M.; Giommi, P.; Puccetti, S. [ASI—Science Data Center, via del Politecnico, I-00133 Rome (Italy); Hayashida, M. [Institute for Cosmic Ray Research, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8582 (Japan); Balokovic, M.; Harrison, F. A. [Cahill Center for Astrophysics, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Madejski, G. M.; Chiang, J. [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Boggs, S. E. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, F. E.; Craig, W. W. [DTU Space—National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Stern, D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Zhang, W. W., E-mail: gianpiero.tagliaferri@brera.inaf.it [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2015-07-10

    Powerful blazars are flat-spectrum radio quasars whose emission is dominated by a Compton component peaking between a few hundred keV and a few hundred MeV. We observed two bright blazars, PKS 2149–306 at redshift z = 2.345 and S5 0836+710 at z = 2.172, in the hard X-ray band with the Nuclear Spectroscopic Telescope Array satellite. Simultaneous soft-X-rays and UV–optical observations were performed with the Swift satellite, while near-infrared (near-IR) data were obtained with the Rapid Eye Mount telescope. To study their variability, we repeated these observations for both sources on a timescale of a few months. While no fast variability was detected during a single observation, both sources were variable in the X-ray band, up to 50%, between the two observations, with larger variability at higher energies. No variability was detected in the optical/NIR band. These data, together with Fermi-Large Area Telescope, Wide-field Infrared Survey Explorer, and other literature data, are then used to study the overall spectral energy distributions (SEDs) of these blazars. Although the jet nonthermal emission dominates the SED, it leaves the UV band unhidden, allowing us to detect the thermal emission of the disk and to estimate the black hole mass. The nonthermal emission is well reproduced by a one-zone leptonic model by the synchrotron, self-Compton, and external Compton processes. Our data are better reproduced if we assume that the location of the dissipation region of the jet, R{sub diss}, is in between the torus and the broad-line region. The observed variability is explained by changing a minimum number of model parameters by a very small amount.

  18. Revealing the Star-Forming Hosts of Luminous Quasars at z~2: A Multi-Wavelength Study

    Science.gov (United States)

    Wethers, Clare; Banerji, Manda; Hewett, Paul; Dark Energy Survey (DES)

    2018-01-01

    Quasars are thought to govern many fundamental processes within galaxies, from quenching star formation to shaping the galaxy itself. In an evolutionary picture of quasars, the most luminous systems (Lbol~1047erg) are thought to evolve from merger-driven starbursts, appearing heavily obscured during their transition to UV-luminous quasars as dust from the decaying starburst is being cleared out of the galaxy. Understanding the connection between dust obscuration, black hole accretion and star formation in luminous quasars undergoing this transition is therefore an important test of such evolutionary models. Host galaxy studies of the most massive and luminous quasars at z>1.5 remain challenging, particularly in the rest-frame UV where a quasar will typically outshine its host galaxy by several orders of magnitude. I will present the first rest-frame UV study for a population of obscured type-1 quasars at z~2 - a peak epoch in both star formation and black hole accretion. By combining deep ground-based imaging from the Dark Energy Survey (DES) with near infra-red observations, I exploit dust obscuration towards the quasar to isolate host galaxy emission, finding obscured quasars to reside in prodigiously star-forming hosts at z~2, with the most actively star-forming galaxies appearing to host the most luminous quasars. Combining these results with new sub-mm observations from SCUBA2, I will present a direct comparison of the unobscured and obscured star formation in this population of dusty quasar hosts.

  19. WISE: From the Dimmest Stars to the most Luminous Galaxies!

    Science.gov (United States)

    Craig, N.; Mendez, B. J.; Wright, E. L.

    2004-12-01

    The Wide-field Infrared Survey Explorer (WISE) Mission, led by UCLA PI Dr. Edward L. Wright is a newly selected MIDEX Mission, scheduled to launch in Summer 2008. WISE will conduct a survey of the entire sky in the infrared (3.5 - 23 microns) with far greater sensitivity than any previous program or mission. WISE will catalogue more than 100,000 asteroids, discover the coolest, dimmest, and nearest stars to the Sun, and determine which are the most luminous galaxies in the Universe. The WISE survey will consist of over a million images, from which hundreds of millions of astronomical objects will be catalogued, providing a vast storehouse of knowledge about the Solar System, the Milky Way, and the Universe. We will discuss our plans for an Education and Public Outreach (E/PO) program for WISE, including how our program will leverage resources from other IR mission E/PO programs such as Spitzer and SOFIA. We will also discuss our plans to partner with the amateur astronomer community to reach out to the K-12 education community, including underserved communities. The University of California, Berkeley's SEGway group from the Space Sciences Laboratory will lead the E/PO efforts of the WISE Mission with formal and informal education partners such as NOAO, Hands-On-Universe, the American Museum of Natural History, Space Science Institute, Space Dynamics Laboratory, the Astronomical Society of the Pacific, and Cornerstone Evaluations. The outreach program of WISE will captivate a wide range of audiences in the formal and informal science education communities with beautiful imagery and engaging science.

  20. Identification in static luminance and color noise

    Science.gov (United States)

    Bijl, Piet; Lucassen, Marcel P.; Roelofsen, Jolanda

    2005-05-01

    If images from multiple sources (e.g. from the different bands of a multi-band sensor) are displayed in color, Signal and Noise may appear as luminance and color differences in the image. As a consequence, the perception of color differences may be important for Target Acquisition performance with fused imagery. Luminance and color can be represented in a 3-D space; in the CIE 1994 color difference model, the three perceptual directions are lightness (L*), chroma (C*) and hue (h*). In this 3-D color space, we performed two perception experiments. In Experiment 1, we measured human observer detection thresholds (JND's) for uniformly distributed static noise (fixed pattern noise) in L*, C* or h* on a uniform background. The results show that the JND for noise in L* is significantly lower than for noise in C* or h*. In Experiment 2, we measured the threshold contrast for identification (orientation discrimination) of a Ushaped test target on a noisy background. With test symbol and background noise in L*, the ratio between signal threshold and noise level is constant. With the symbol in a different direction, we found little dependency on noise level. The results may be used to optimize the use of color to human detection and identification performance with multi-band systems.

  1. Use of Meteosat data to produce sky luminance maps

    OpenAIRE

    Ineichen, Pierre

    1996-01-01

    The objective of the subtask is to derive a model to evaluate the luminance distribution of the sky vault on the basis of Meteosat data. This information is a key element in the field of building energy saving, it is the basis of indoor daylight calculation. Evaluation programs like Genelux (LASH-ENTPE) need this sky luminance distribution to perform their calculations. Sky luminance distribution models have been developed in the last years on the basis of horizontal diffuse illuminance. Thei...

  2. The psychophysics of detecting binocular discrepancies of luminance.

    Science.gov (United States)

    Formankiewicz, Monika A; Mollon, J D

    2009-07-01

    In the natural world, a binocular discrepancy of luminance can signal a glossy surface. Using a spatial forced choice task, we have measured the ability of subjects to detect binocular luminance disparities. We show that the detection of binocular luminance disparity shares several basic psychophysical features with the detection of surface properties such as lightness and chromaticity: an approximation to Weber's Law, spatial summation, temporal summation, and a deterioration with increasing eccentricity. We also discuss whether color-deficient subjects could derive reliable information about chromaticity from the binocular disparities of luminance induced by a monocularly worn color filter.

  3. Adaptive display luminance for viewing smartphones under low illuminance.

    Science.gov (United States)

    Na, Nooree; Suk, Hyeon-Jeong

    2015-06-29

    The study investigates the optimal display luminance for viewing smartphones in conditions of low illuminance. This proposes a model of adaptive display in that display luminance changes gradually with the passage of watching time. It starts at a fairly low display luminance of 10 cd/m2, and after 10 seconds, the luminance increases slowly until it reaches 40 cd/m2 for 20 seconds and maintains the luminance. For the development of the model, an experiment was conducted to identify the optimal luminance for initial viewing and that for continuous viewing, as well as the change speed of display luminance. In order to validate the model, users' subjective judgments and activation of alpha rhythm were observed, and the result confirmed the superiority of the adaptive display luminance compared to the current display luminance in terms of physiological comfort and psychological satisfaction. It is expected that this study contributes to the pleasing use of displays at night under low illuminance by applying to diverse types of display devices.

  4. Luminous and Variable Stars in M31 and M33. V. The Upper HR Diagram

    Energy Technology Data Exchange (ETDEWEB)

    Humphreys, Roberta M.; Davidson, Kris; Hahn, David [Minnesota Institute for Astrophysics, 116 Church St SE, University of Minnesota, Minneapolis, MN 55455 (United States); Martin, John C. [Barber Observatory, University of Illinois, Springfield, IL 62703 (United States); Weis, Kerstin, E-mail: roberta@umn.edu [Astronomical Institute, Ruhr-Universitaet Bochum (Germany)

    2017-07-20

    We present HR diagrams for the massive star populations in M31 and M33, including several different types of emission-line stars: the confirmed luminous blue variables (LBVs), candidate LBVs, B[e] supergiants, and the warm hypergiants. We estimate their apparent temperatures and luminosities for comparison with their respective massive star populations and evaluate the possible relationships of these different classes of evolved, massive stars, and their evolutionary state. Several of the LBV candidates lie near the LBV/S Dor instability strip that supports their classification. Most of the B[e] supergiants, however, are less luminous than the LBVs. Many are very dusty with the infrared flux contributing one-third or more to their total flux. They are also relatively isolated from other luminous OB stars. Overall, their spatial distribution suggests a more evolved state. Some may be post-RSGs (red supergiants) like the warm hypergiants, and there may be more than one path to becoming a B[e] star. There are sufficient differences in the spectra, luminosities, spatial distribution, and the presence or lack of dust between the LBVs and B[e] supergiants to conclude that one group does not evolve into the other.

  5. Chromatic blur perception in the presence of luminance contrast.

    Science.gov (United States)

    Jennings, Ben J; Kingdom, Frederick A A

    2017-06-01

    Hel-Or showed that blurring the chromatic but not the luminance layer of an image of a natural scene failed to elicit any impression of blur. Subsequent studies have suggested that this effect is due either to chromatic blur being masked by spatially contiguous luminance edges in the scene (Journal of Vision 13 (2013) 14), or to a relatively compressed transducer function for chromatic blur (Journal of Vision 15 (2015) 6). To test between the two explanations we conducted experiments using as stimuli both images of natural scenes as well as simple edges. First, we found that in color-and-luminance images of natural scenes more chromatic blur was needed to perceptually match a given level of blur in an isoluminant, i.e. colour-only scene. However, when the luminance layer in the scene was rotated relative to the chromatic layer, thus removing the colour-luminance edge correlations, the matched blur levels were near equal. Both results are consistent with Sharman et al.'s explanation. Second, when observers matched the blurs of luminance-only with isoluminant scenes, the matched blurs were equal, against Kingdom et al.'s prediction. Third, we measured the perceived blur in a square-wave as a function of (i) contrast (ii) number of luminance edges and (iii) the relative spatial phase between the colour and luminance edges. We found that the perceived chromatic blur was dependent on both relative phase and the number of luminance edges, or dependent on the luminance contrast if only a single edge is present. We conclude that this Hel-Or effect is largely due to masking of chromatic blur by spatially contiguous luminance edges. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Luminal pulse velocity in a superluminal medium

    Science.gov (United States)

    Amano, Heisuke; Tomita, Makoto

    2015-12-01

    To investigate the physical meaning of pulse peak in fast and slow light media, we investigated propagation of differently shaped pulses experimentally, controlling the sharpness of the pulse peak. Symmetric behavior with respect to fast and slow light was observed in traditional Gaussian pulses; that is, propagated pulses were advanced or delayed, respectively, whereas the pulse shape remained unchanged. This symmetry broke down when the pulse peak was sharpened; in the fast light medium, the sharp pulse peak propagated with luminal velocity, and the transmitted pulse deformed into a characteristic asymmetric profile. In contrast, in the slow light medium, a time-delayed smooth peak appeared with a bending point at t =0 . This symmetry breaking with respect to fast and slow light is a universal characteristic of pulse propagation in causal dispersive systems. The sharp pulse peak can be recognized as a bending nonanalytical point and may be capable of transferring information.

  7. Luminous flux and colour maintenance investigation of integrated LED lamps

    DEFF Research Database (Denmark)

    Corell, Dennis Dan; Thorseth, Anders; Dam-Hansen, Carsten

    2014-01-01

    This article will present an investigation of the luminous flux and colour maintenance of white LED based retrofit lamps. The study includes 23 different types of integrated LED lamps, covering 18 directional and 5 non-directional. Luminous flux and colour data for operation up to 20000 h has been...

  8. Luminal breast cancer metastasis is dependent on estrogen signaling

    NARCIS (Netherlands)

    Ganapathy, Vidya; Banach-Petrosky, Whitney; Xie, Wen; Kareddula, Aparna; Nienhuis, Hilde; Miles, Gregory; Reiss, Michael

    Luminal breast cancer is the most frequently encountered type of human breast cancer and accounts for half of all breast cancer deaths due to metastatic disease. We have developed new in vivo models of disseminated human luminal breast cancer that closely mimic the human disease. From initial

  9. Covariation of Color and Luminance Facilitate Object Individuation in Infancy

    Science.gov (United States)

    Woods, Rebecca J.; Wilcox, Teresa

    2010-01-01

    The ability to individuate objects is one of our most fundamental cognitive capacities. Recent research has revealed that when objects vary in color or luminance alone, infants fail to individuate those objects until 11.5 months. However, color and luminance frequently covary in the natural environment, thus providing a more salient and reliable…

  10. Observations of the Hubble Deep Field with the Infrared Space Observatory .1. Data reduction, maps and sky coverage

    DEFF Research Database (Denmark)

    Serjeant, S.B.G.; Eaton, N.; Oliver, S.J.

    1997-01-01

    We present deep imaging at 6.7 and 15 mu m from the CAM instrument on the Infrared Space Observatory (ISO), centred on the Hubble Deep Field (HDF). These are the deepest integrations published to date at these wavelengths in any region of sky. We discuss the observational strategy and the data re...... data yield strong evidence that future infrared missions (such as SIRTF, FIRST and WIRE) as well as SCUBA and millimetre arrays will easily detect field galaxies out to comparably high redshifts....

  11. A Satellite-Based Sky Luminance Model for the Tropics

    Directory of Open Access Journals (Sweden)

    Serm Janjai

    2013-01-01

    Full Text Available This paper presents a sky luminance model for the tropics. The model is mathematically expressed as a multiplication of two functions. These are φ, which is a function of the zenith angle of a sky element and solar zenith angle, and f, which is a function of the angle between the sky element and the sun. To obtain the analytical forms of these functions, the sky luminance data collected at Nakhon Pathom (13.82°N, 100.04°E, Thailand, during a four-year period were analyzed. Additionally, satellite-derived cloud index at the position of the sky luminance measurements during the same period was estimated. Based on values of the cloud index, the skies were classified into 10 types, from clear to overcast skies. By using appropriate grouping and mathematical operation of the sky luminance data, the values of the two functions were obtained and then fitted with empirical equations. The multiplication of these equations gives the final form of the sky luminance model. To validate the model, it was used to calculate the relative sky luminance at other three sites in the tropics. It was found that values of relative sky luminance calculated from the model and those obtained from the measurements were in reasonable agreement.

  12. Spatial dependencies between local luminance and contrast in natural images.

    Science.gov (United States)

    Lindgren, Jussi T; Hurri, Jarmo; Hyvärinen, Aapo

    2008-09-23

    Previous research has suggested only weak statistical dependencies between local luminance and contrast in natural images. Here we study luminance and contrast in natural images using established measures and show that when multiple measurements of these two local quantities are taken in different spatial locations across the visual field, strong dependencies are revealed that were not apparent in previous pointwise (single-site) analyses. We present a few simple experiments demonstrating this spatial dependency of luminance and contrast and show that the luminance measurements can be used to approximate the contrast measurements. We also show that relying on higher-order statistics, independent component analysis learns paired spatial features for luminance and contrast. These features are shown to share orientation and localization, with the filters corresponding to the features dependent in their outputs. Finally, we demonstrate that the found dependencies also exist in artificial images generated from a dead leaves model, implying that simple image phenomena may suffice to account for the dependencies. Our results indicate that local luminance and contrast computations do not recover independent information sources from the visual signal. Subsequently, our results predict spatial processing of local luminance and contrast to be non-separable in visual systems.

  13. Stellar Populations of Luminous Evolved Galaxies at z ~ 1.5

    Science.gov (United States)

    McGrath, Elizabeth J.; Stockton, Alan; Canalizo, Gabriela

    2007-11-01

    Observational evidence has been mounting over the past decade that at least some luminous (~2L*) galaxies have formed nearly all of their stars within a short period of time, only (1-2)×109 yr after the big bang. These are examples of the first major episodes of star formation in the universe and provide insights into the formation of the earliest massive galaxies. We have examined in detail the stellar populations of six z~1.5 galaxies that appear to be passively evolving, using both ground- and space-based photometry covering rest-frame UV to visible wavelengths. In addition, we have obtained medium-resolution spectroscopy for five of the six galaxies, covering the rest-frame UV portion of the spectrum. Spectral synthesis modeling for four of these galaxies favors a single burst of star formation more than 1 Gyr before the observed epoch. The other two exhibit slightly younger ages with a higher dust content and evidence for a small contribution from either recent star formation or active nuclei. The implied formation redshifts for the oldest of these sources are consistent with previous studies of passive galaxies at high redshift, and improved stellar modeling has shown these results to be quite robust. It now seems clear that any valid galaxy formation scenario must be able to account for these massive (~2×1011 Msolar) galaxies at very early times in the universe. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial support of the W. M. Keck Foundation. Results are also based in part on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science

  14. Demography of High-Redshift AGN

    Directory of Open Access Journals (Sweden)

    Fabrizio Fiore

    2012-01-01

    Universe during its infancy. We review the latest searches for high-z AGN in the deepest X-ray field so far, the Chandra Deep Field South (CDFS 4 Msecond exposure. We do not confirm the positive detection of a signal in the stacked Chandra images at the position of z~6 galaxies recently reported by Treister and collaborators (2011. We present z>3 X-ray sources number counts in the 0.5–2 keV band, obtained joining CDFS faint detections (see Fiore et al. (2011, with Chandra-COSMOS and XMM-COSMOS detections. We use these number counts to make predictions for surveys with three mission concepts: Athena, WFXT, and a Super-Chandra.

  15. Studying the high redshift Universe with Athena

    Science.gov (United States)

    O'Brien, P. T.

    2016-04-01

    Athena is the second large mission selected in the ESA Cosmic Vision plan. With its large collecting area, high spectral-energy resolution (X-IFU instrument) and impressive grasp (WFI instrument), Athena will truly revolutionise X-ray astronomy. The most prodigious sources of high-energy photons are often transitory in nature. Athena will provide the sensitivity and spectral resolution coupled with rapid response to enable the study of the dynamic sky. Potential sources include: distant Gamma-Ray Bursts to probe the reionisation epoch and find ‘missing’ baryons in the cosmic web; tidal disruption events to reveal dormant supermassive and intermediate-mass black holes; and supernova explosions to understand progenitors and their environments.Using detailed simulations, we illustrate Athena’s extraordinary capabilities for transients out to the highest redshifts and show how it will be able to constrain the nature of explosive transients including gas metallicity and dynamics, constraining environments and progenitors.

  16. Modelling luminous-blue-variable isolation

    Science.gov (United States)

    Aghakhanloo, Mojgan; Murphy, Jeremiah W.; Smith, Nathan; Hložek, Renée

    2017-11-01

    Observations show that luminous blue variables (LBVs) are far more dispersed than massive O-type stars, and Smith & Tombleson suggested that these large separations are inconsistent with a single-star evolution model of LBVs. Instead, they suggested that the large distances are most consistent with binary evolution scenarios. To test these suggestions, we modelled young stellar clusters and their passive dissolution, and we find that, indeed, the standard single-star evolution model is mostly inconsistent with the observed LBV environments. If LBVs are single stars, then the lifetimes inferred from their luminosity and mass are far too short to be consistent with their extreme isolation. This implies that there is either an inconsistency in the luminosity-to-mass mapping or the mass-to-age mapping. In this paper, we explore binary solutions that modify the mass-to-age mapping and are consistent with the isolation of LBVs. For the binary scenarios, our crude models suggest that LBVs are rejuvenated stars. They are either the result of mergers or they are mass gainers and received a kick when the primary star exploded. In the merger scenario, if the primary is about 19 M⊙, then the binary has enough time to wander far afield, merge and form a rejuvenated star. In the mass-gainer and kick scenario, we find that LBV isolation is consistent with a wide range of kick velocities, anywhere from 0 to ˜105 km s-1. In either scenario, binarity seems to play a major role in the isolation of LBVs.

  17. STAR FORMATION IN TWO LUMINOUS SPIRAL GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, Deidre A.; Ashburn, Allison; Wright, Teresa [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Elmegreen, Bruce G. [IBM T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Rubin, Vera C. [Carnegie Institution of Washington, 5241 Broad Branch Road NW, Washington, DC 20015 (United States); Józsa, Gyula I. G.; Struve, Christian [ASTRON (Netherlands Organisation for Scientific Research NWO), Oude Hoogeveensedijk 4, 7991-PD Dwingeloo (Netherlands)

    2013-10-01

    We examined star formation in two very luminous (M{sub V} = –22 to –23) Sc-type spiral galaxies, NGC 801 and UGC 2885, using ultra-deep Hα images. We combine these Hα images with UBV and Two-Micron All-Sky Survey JHK images and H I maps to explore the star formation characteristics of disk galaxies at high luminosity. Hα traces star formation in these galaxies to 4-6 disk scale lengths, but the lack of detection of Hα further out is likely due to the loss of Lyman continuum photons. Considering gravitational instabilities alone, we find that the gas and stars in the outer regions are marginally stable in an average sense, but considering dissipative gas and radial and azimuthal forcing, the outer regions are marginally unstable to forming spiral arms. Star formation is taking place in spiral arms, which are regions of locally higher gas densities. Furthermore, we have traced smooth exponential stellar disks over four magnitudes in V-band surface brightness and 4-6 disk scale lengths, in spite of a highly variable gravitational instability parameter. Thus, gravitational instability thresholds do not seem relevant to the stellar disk. One possibility for creating an exponential disk is that the molecular cloud densities and star formation rates have exponential profiles and this fact forces the stellar disk to build up such a profile. Another possibility is that the stellar disk is continuously adjusted to an exponential shape regardless of the star formation profile, for example, through global dynamical processes that scatter stars. However, such scattering processes are only known to operate in spiral systems, in which case they cannot explain the same dilemma of smooth exponential disks observed in dwarf irregular galaxies.

  18. LLAMA: normal star formation efficiencies of molecular gas in the centres of luminous Seyfert galaxies

    Science.gov (United States)

    Rosario, D. J.; Burtscher, L.; Davies, R. I.; Koss, M.; Ricci, C.; Lutz, D.; Riffel, R.; Alexander, D. M.; Genzel, R.; Hicks, E. H.; Lin, M.-Y.; Maciejewski, W.; Müller-Sánchez, F.; Orban de Xivry, G.; Riffel, R. A.; Schartmann, M.; Schawinski, K.; Schnorr-Müller, A.; Saintonge, A.; Shimizu, T.; Sternberg, A.; Storchi-Bergmann, T.; Sturm, E.; Tacconi, L.; Treister, E.; Veilleux, S.

    2018-02-01

    Using new Atacama Pathfinder Experiment and James Clerk Maxwell Telescope spectroscopy of the CO 2→1 line, we undertake a controlled study of cold molecular gas in moderately luminous (Lbol = 1043-44.5 erg s-1) active galactic nuclei (AGN) and inactive galaxies from the Luminous Local AGN with Matched Analogs (LLAMA) survey. We use spatially resolved infrared photometry of the LLAMA galaxies from 2MASS, the Wide-field Infrared Survey Explorer the Infrared Astronomical Satellite and the Herschel Space Observatory (Herschel), corrected for nuclear emission using multicomponent spectral energy distribution fits, to examine the dust-reprocessed star formation rates, molecular gas fractions and star formation efficiencies (SFEs) over their central 1-3 kpc. We find that the gas fractions and central SFEs of both active and inactive galaxies are similar when controlling for host stellar mass and morphology (Hubble type). The equivalent central molecular gas depletion times are consistent with the discs of normal spiral galaxies in the local Universe. Despite energetic arguments that the AGN in LLAMA should be capable of disrupting the observable cold molecular gas in their central environments, our results indicate that nuclear radiation only couples weakly with this phase. We find a mild preference for obscured AGN to contain higher amounts of central molecular gas, which suggests connection between AGN obscuration and the gaseous environment of the nucleus. Systems with depressed SFEs are not found among the LLAMA AGN. We speculate that the processes that sustain the collapse of molecular gas into dense pre-stellar cores may also be a prerequisite for the inflow of material on to AGN accretion discs.

  19. Production of L-Asparaginase by the marine luminous bacteria

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaiah, N.; Chandramohan, D.

    Fortythree strains of luminous bacteria, belonging to 4 species, (Vibrio harveyi, V. fischeri, Photobacterium leiognathi and P. phosphoreum) isolated from different marine samples, were examined for the production of L-asparaginase. Presence...

  20. Ecology and biology of luminous bacteria in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaiah, N.; Chandramohan, D.

    the water column with temperatures lower than 25 degrees C. Bacterial luminescence in all the seawater samples was very low indicating energy conservation mechanism in free living luminous procaryotes. In contrast, a 10000 fold higher bacterial luminescence...

  1. Luminous device with dual daytime and nighttime use of energy

    OpenAIRE

    Lira-Cantú, Mónica

    2010-01-01

    [EN] Applicable both indoors and outdoors, in desk lamps, street lamps, spotlights in 1.", football stadiums, etc., ofthe type which comprises a housing, the interior of which contains a luminous element , either a light bulb, LEDs or the like, said luminous device being provided with at least one transparent or semi-transparent photovoltaic solar cell which is used to convert solar energy into electrical energy during the hours of sunlight and to convert light energy int...

  2. Hyperluminous Infrared Galaxies: The QSO-2's

    Science.gov (United States)

    Hines, D. C.

    1998-12-01

    QSO-like nuclei have been detected in the most luminous infrared galaxies known, and in many other ultraluminous infrared galaxies with ``warm'' far-IR colors. These misdirected QSOs are revealed by the morphology and spectrum of light polarized by scattering. In particular, P09104+4109 and F15307+3252 exhibit spectacular bipolar morphology in WFPC2 and NICMOS images, and broad, polarized emission-lines in their polarized spectra. This strongly suggests that the QSO nuclei are surrounded by dusty tori which obscure our direct view, but allow nuclear emission to escape through the open poles to be subsequently scattered (thus polarized) into our line of sight. Even though the radio-infrared correlation indicates ongoing star formation, if viewed from the vantage point of the scattering material, these objects would be indistinguishable from typical luminous QSOs. Hence, they should be classified as ``QSO-2's.'' These results imply that: QSO activity is intimately related to the ultraluminous infrared galaxy phenomenon. A significant fraction of the total luminosity can be generated by the non-stellar central engines. QSOs may contribute significantly to the cosmic infrared background.

  3. PROPERTIES OF NEWLY FORMED DUST GRAINS IN THE LUMINOUS TYPE IIn SUPERNOVA 2010jl

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, K.; Nozawa, T.; Folatelli, G.; Moriya, T. J.; Nomoto, K.; Bersten, M.; Quimby, R. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Sahu, D. K.; Anupama, G. C. [Indian Institute of Astrophysics, Koramangala, Bangalore 560 034 (India); Minowa, Y.; Pyo, T.-S. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Motohara, K.; Kitagawa, Y. [Institute of Astronomy, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Ueno, I.; Kawabata, K. S.; Yamanaka, M. [Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Kozasa, T. [Department of Cosmosciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Iye, M., E-mail: keiichi.maeda@ipmu.jp [National Astronomical Observatory, Mitaka, Tokyo (Japan)

    2013-10-10

    Supernovae (SNe) have been proposed to be the main production sites of dust grains in the universe. However, our knowledge of their importance to dust production is limited by observationally poor constraints on the nature and amount of dust particles produced by individual SNe. In this paper, we present a spectrum covering optical through near-Infrared (NIR) light of the luminous Type IIn supernova 2010jl around one and a half years after the explosion. This unique data set reveals multiple signatures of newly formed dust particles. The NIR portion of the spectrum provides a rare example where thermal emission from newly formed hot dust grains is clearly detected. We determine the main population of the dust species to be carbon grains at a temperature of ∼1350-1450 K at this epoch. The mass of the dust grains is derived to be ∼(7.5-8.5) × 10{sup –4} M{sub ☉}. Hydrogen emission lines show wavelength-dependent absorption, which provides a good estimate of the typical size of the newly formed dust grains (∼< 0.1 μm, and most likely ∼< 0.01 μm). We believe the dust grains were formed in a dense cooling shell as a result of a strong SN-circumstellar media (CSM) interaction. The dust grains occupy ∼10% of the emitting volume, suggesting an inhomogeneous, clumpy structure. The average CSM density must be ∼> 3 × 10{sup 7} cm{sup –3}, corresponding to a mass loss rate of ∼> 0.02 M{sub ☉} yr{sup –1} (for a mass loss wind velocity of ∼100 km s{sup –1}). This strongly supports a scenario in which SN 2010jl and probably other luminous SNe IIn are powered by strong interactions within very dense CSM, perhaps created by Luminous-Blue-Variable-like eruptions within the last century before the explosion.

  4. The Design and Capabilities of the EXIST Optical and Infra-Red Telescope (IRT)

    Science.gov (United States)

    Kutyrev, A S.; Moseley, S. H.; Golisano, C.; Gong, Q.; Allen, B. T.; Gehrels, N.; Grindlay, J. E.; Hong, J. S.; Woodgate, B. E.

    2010-01-01

    The Infra-Red Telescope is a critical element of the EXIST (Energetic X-Ray Imaging Survey Telescope) observatory. The primary goal of the IRT is to obtain photometric and spectroscopic measurements of high redshift (> or =6) gamma ray reaching to the epoque of reionization. The photometric and spectral capabilities of the IRT will allow to use GRB afterglow as probes of the composition and ionization state of the intergalactic medium of the young universe. A prompt follow up (within three minutes) of the transient discovered by the EXIST makes IRT a unique tool for detection and study of these events in the infrared and optical wavelength, which is particularly valuable at wavelengths unavailable to the ground based observatories. We present the results of the mission study development on the IRT as part of the EXIST observatory. Keywords: infrared spectroscopy, space telescope, gamma ray bursts, early universe

  5. A stent for co-delivering paclitaxel and nitric oxide from abluminal and luminal surfaces: Preparation, surface characterization, and in vitro drug release studies

    Energy Technology Data Exchange (ETDEWEB)

    Gallo, Annemarie; Mani, Gopinath, E-mail: Gopinath.Mani@usd.edu

    2013-08-15

    Most drug-eluting stents currently available are coated with anti-proliferative drugs on both abluminal (toward blood vessel wall) and luminal (toward lumen) surfaces to prevent neointimal hyperplasia. While the abluminal delivery of anti-proliferative drugs is useful for controlling neointimal hyperplasia, the luminal delivery of such drugs impairs or prevents endothelialization which causes late stent thrombosis. This research is focused on developing a bidirectional dual drug-eluting stent to co-deliver an anti-proliferative agent (paclitaxel – PAT) and an endothelial cell promoting agent (nitric oxide – NO) from abluminal and luminal surfaces of the stent, respectively. Phosphonoacetic acid, a polymer-free drug delivery platform, was initially coated on the stents. Then, the PAT and NO donor drugs were co-coated on the abluminal and luminal stent surfaces, respectively. The co-coating of drugs was collectively confirmed by the surface characterization techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), 3D optical surface profilometry, and contact angle goniometry. SEM showed that the integrity of the co-coating of drugs was maintained without delamination or cracks formation occurring during the stent expansion experiments. In vitro drug release studies showed that the PAT was released from the abluminal stent surfaces in a biphasic manner, which is an initial burst followed by a slow and sustained release. The NO was burst released from the luminal stent surfaces. Thus, this study demonstrated the co-delivery of PAT and NO from abluminal and luminal stent surfaces, respectively. The stent developed in this study has potential applications in inhibiting neointimal hyperplasia as well as encouraging luminal endothelialization to prevent late stent thrombosis.

  6. Study of lumineers' interfaces by means of optical coherence tomography

    Science.gov (United States)

    de Andrade Borges, Erica; Fernandes Cassimiro-Silva, Patrícia; Osório Fernandes, Luana; Leônidas Gomes, Anderson Stevens

    2015-06-01

    OCT has been used to evaluate dental materials, and is employed here to evaluate lumineers for the first time. Lumineers are used as esthetical indirect restoration, and after wearing and aging, several undesirable features such as gaps, bubbles and mismatch can appear in which would only be seen by invasive analysis. The OCT (spectral domain SD-OCT, 930nm central wavelength) was used to evaluate noninvasively the lumineer- cement-tooth interface. We analyzed 20 specimens of lumineers-teeth that were prepared in bovine teeth and randomly allocated in 4 experimental groups (n=5) with two different cementation techniques and two different types of cementing agent (RelyX U200 and RelyX Veneer, 3M ESPE, with the adhesive recommended by the manufacture). The lumineers were made of lithium disilicate and obtained using a vacuum injection technique. The analysis was performed by using 2D and 3D OCT images, obtained before and after cementing and the thermal cycling process to simulate thermal stress in a oral cavity. Initial measurements showed that the SD-OCT was able to see through the 500μm thick lumineer, as delivered by the fabricant, and internal stress was observed. Failures were found in the cementing process and also after ageing simulation by thermal cycling. The adhesive failures as bubbles, gaps and degradation of the cementation line are the natural precursors of other defects reported by several studies of clinical follow-up (detachments, fractures and cracks). Bubble dimensions ranging from 146 μm to 1427 μm were measured and the OCT was validated as an investigative and precise tool for evaluation of the lumineer-cement-tooth.

  7. Intelligent Luminance Control of Lighting Systems Based on Imaging Sensor Feedback

    Directory of Open Access Journals (Sweden)

    Haoting Liu

    2017-02-01

    Full Text Available An imaging sensor-based intelligent Light Emitting Diode (LED lighting system for desk use is proposed. In contrast to the traditional intelligent lighting system, such as the photosensitive resistance sensor-based or the infrared sensor-based system, the imaging sensor can realize a finer perception of the environmental light; thus it can guide a more precise lighting control. Before this system works, first lots of typical imaging lighting data of the desk application are accumulated. Second, a series of subjective and objective Lighting Effect Evaluation Metrics (LEEMs are defined and assessed for these datasets above. Then the cluster benchmarks of these objective LEEMs can be obtained. Third, both a single LEEM-based control and a multiple LEEMs-based control are developed to realize a kind of optimal luminance tuning. When this system works, first it captures the lighting image using a wearable camera. Then it computes the objective LEEMs of the captured image and compares them with the cluster benchmarks of the objective LEEMs. Finally, the single LEEM-based or the multiple LEEMs-based control can be implemented to get a kind of optimal lighting effect. Many experiment results have shown the proposed system can tune the LED lamp automatically according to environment luminance changes.

  8. Intelligent Luminance Control of Lighting Systems Based on Imaging Sensor Feedback

    Science.gov (United States)

    Liu, Haoting; Zhou, Qianxiang; Yang, Jin; Jiang, Ting; Liu, Zhizhen; Li, Jie

    2017-01-01

    An imaging sensor-based intelligent Light Emitting Diode (LED) lighting system for desk use is proposed. In contrast to the traditional intelligent lighting system, such as the photosensitive resistance sensor-based or the infrared sensor-based system, the imaging sensor can realize a finer perception of the environmental light; thus it can guide a more precise lighting control. Before this system works, first lots of typical imaging lighting data of the desk application are accumulated. Second, a series of subjective and objective Lighting Effect Evaluation Metrics (LEEMs) are defined and assessed for these datasets above. Then the cluster benchmarks of these objective LEEMs can be obtained. Third, both a single LEEM-based control and a multiple LEEMs-based control are developed to realize a kind of optimal luminance tuning. When this system works, first it captures the lighting image using a wearable camera. Then it computes the objective LEEMs of the captured image and compares them with the cluster benchmarks of the objective LEEMs. Finally, the single LEEM-based or the multiple LEEMs-based control can be implemented to get a kind of optimal lighting effect. Many experiment results have shown the proposed system can tune the LED lamp automatically according to environment luminance changes. PMID:28208781

  9. Intelligent Luminance Control of Lighting Systems Based on Imaging Sensor Feedback.

    Science.gov (United States)

    Liu, Haoting; Zhou, Qianxiang; Yang, Jin; Jiang, Ting; Liu, Zhizhen; Li, Jie

    2017-02-09

    An imaging sensor-based intelligent Light Emitting Diode (LED) lighting system for desk use is proposed. In contrast to the traditional intelligent lighting system, such as the photosensitive resistance sensor-based or the infrared sensor-based system, the imaging sensor can realize a finer perception of the environmental light; thus it can guide a more precise lighting control. Before this system works, first lots of typical imaging lighting data of the desk application are accumulated. Second, a series of subjective and objective Lighting Effect Evaluation Metrics (LEEMs) are defined and assessed for these datasets above. Then the cluster benchmarks of these objective LEEMs can be obtained. Third, both a single LEEM-based control and a multiple LEEMs-based control are developed to realize a kind of optimal luminance tuning. When this system works, first it captures the lighting image using a wearable camera. Then it computes the objective LEEMs of the captured image and compares them with the cluster benchmarks of the objective LEEMs. Finally, the single LEEM-based or the multiple LEEMs-based control can be implemented to get a kind of optimal lighting effect. Many experiment results have shown the proposed system can tune the LED lamp automatically according to environment luminance changes.

  10. Exploring the multifaceted circumstellar environment of the luminous blue variable HR Carinae

    Science.gov (United States)

    Buemi, C. S.; Trigilio, C.; Leto, P.; Umana, G.; Ingallinera, A.; Cavallaro, F.; Cerrigone, L.; Agliozzo, C.; Bufano, F.; Riggi, S.; Molinari, S.; Schillirò, F.

    2017-03-01

    We present a multiwavelength study of the Galactic luminous blue variable HR Carinae, based on new high-resolution mid-infrared (IR) and radio images obtained with the Very Large Telescope (VLT) and the Australia Telescope Compact Array (ATCA), which have been complemented by far-infrared Herschel-Photodetector Array Camera and Spectrometer (PACS) observations and ATCA archive data. The Herschel images reveal the large-scale distribution of the dusty emitting nebula, which extends mainly to the north-east direction, up to 70 arcsec from the central star, and is oriented along the direction of the space motion of the star. In the mid-infrared images, the brightness distribution is characterized by two arc-shaped structures, tracing an inner envelope surrounding the central star more closely. At radio wavelengths, the ionized gas emission lies on the opposite side of the cold dust with respect to the position of the star, as if the ionized front were confined by the surrounding medium in the north-south direction. Comparison with previous data indicates significant changes in the radio nebula morphology and in the mass-loss rate from the central star, which has increased from 6.1 × 10-6 M⊙ yr-1 in 1994-1995 to 1.17 × 10-5 M⊙ yr-1 in 2014. We investigate possible scenarios that could have generated the complex circumstellar environment revealed by our multiwavelength data.

  11. Infrared-faint radio sources remain undetected at far-infrared wavelengths. Deep photometric observations using the Herschel Space Observatory

    Science.gov (United States)

    Herzog, A.; Norris, R. P.; Middelberg, E.; Spitler, L. R.; Leipski, C.; Parker, Q. A.

    2015-08-01

    Context. Showing 1.4 GHz flux densities in the range of a few to a few tens of mJy, infrared-faint radio sources (IFRS) are a type of galaxy characterised by faint or absent near-infrared counterparts and consequently extreme radio-to-infrared flux density ratios up to several thousand. Recent studies showed that IFRS are radio-loud active galactic nuclei (AGNs) at redshifts ≳2, potentially linked to high-redshift radio galaxies (HzRGs). Aims: This work explores the far-infrared emission of IFRS, providing crucial information on the star forming and AGN activity of IFRS. Furthermore, the data enable examining the putative relationship between IFRS and HzRGs and testing whether IFRS are more distant or fainter siblings of these massive galaxies. Methods: A sample of six IFRS was observed with the Herschel Space Observatory between 100 μm and 500 μm. Using these results, we constrained the nature of IFRS by modelling their broad-band spectral energy distribution (SED). Furthermore, we set an upper limit on their infrared SED and decomposed their emission into contributions from an AGN and from star forming activity. Results: All six observed IFRS were undetected in all five Herschel far-infrared channels (stacking limits: σ = 0.74 mJy at 100 μm, σ = 3.45 mJy at 500 μm). Based on our SED modelling, we ruled out the following objects to explain the photometric characteristics of IFRS: (a) known radio-loud quasars and compact steep-spectrum sources at any redshift; (b) starburst galaxies with and without an AGN and Seyfert galaxies at any redshift, even if the templates were modified; and (c) known HzRGs at z ≲ 10.5. We find that the IFRS analysed in this work can only be explained by objects that fulfil the selection criteria of HzRGs. More precisely, IFRS could be (a) known HzRGs at very high redshifts (z ≳ 10.5); (b) low-luminosity siblings of HzRGs with additional dust obscuration at lower redshifts; (c) scaled or unscaled versions of Cygnus A at any

  12. The Formation of Primordial Luminous Objects

    Energy Technology Data Exchange (ETDEWEB)

    Ripamonti, Emanuele; /Kapteyn Astron. Inst., Groningen; Abel, Tom; /KIPAC, Menlo Park

    2005-08-04

    formed and how they influence subsequent structure formation. In these notes we will leave the discussion of feedback to lecture notes by Ferrara & Salvaterra and by Madau & Haardt in this same book and focus only on the aspects of the formation of the first objects. The advent of cosmological numerical hydrodynamics in particular allow a fresh new look at these questions. Hence, these notes will touch on aspects of theoretical cosmology to chemistry, computer science, hydrodynamics and atomic physics. For further reading and more references on the subject we refer the reader to other relevant reviews such as Barkana & Loeb 2001, and more recently Ciardi & Ferrara 2004, Glover 2004 and Bromm & Larson 2004. In these notes, we try to give a brief introduction to only the most relevant aspects. We will start with a brief overview of the relevant cosmological concepts in section 2, followed by a discussion of the properties of primordial material (with particular emphasis to its cooling and its chemistry) in section 3. We will then review the technique and the results of numerical simulations in sections 4 and 5: the former will deal with detailed 3D simulations of the formation of gaseous clouds which are likely to transform into luminous objects, while the latter will examine results (mostly from 1D codes) about the modalities of such transformation. Finally, in section 6 we will critically discuss the results of the previous sections, examining their consequences and comparing them to our present knowledge of the universe.

  13. Early ERPs to faces: aging, luminance, and individual differences.

    Science.gov (United States)

    Bieniek, Magdalena M; Frei, Luisa S; Rousselet, Guillaume A

    2013-01-01

    Recently, Rousselet et al. reported a 1 ms/year delay in visual processing speed in a sample of healthy aged 62 subjects (Frontiers in Psychology 2010, 1:19). Here, we replicate this finding in an independent sample of 59 subjects and investigate the contribution of optical factors (pupil size and luminance) to the age-related slowdown and to individual differences in visual processing speed. We conducted two experiments. In experiment 1 we recorded EEG from subjects aged 18-79. Subjects viewed images of faces and phase scrambled noise textures under nine luminance conditions, ranging from 0.59 to 60.8 cd/m(2). We manipulated luminance using neutral density filters. In experiment 2, 10 young subjects (age affect the onsets of the face-texture ERP differences. Furthermore, luminance modulated the entire ERP time-course from 60 to 500 ms. Luminance effects peaked in the N170 time window and were independent of age. Importantly, senile miosis and individual differences in pupil size did not account for aging differences and inter-subject variability in processing speed. The pinhole manipulation also failed to match the ERPs of old subjects to those of young subjects. Overall, our results strongly suggest that early ERPs to faces (<200 ms) are delayed by aging and that these delays are of cortical, rather than optical origin. Our results also demonstrate that even late ERPs to faces are modulated by low-level factors.

  14. Association of proteasomal activity with metastasis in luminal breast cancer

    Science.gov (United States)

    Shashova, E. E.; Fesik, E. A.; Doroshenko, A. V.

    2017-09-01

    Chimotrypsin-like (ChTL) and caspase-like (CL) proteasomal activities were investigated in different variants of the tumor progression of luminal breast cancer. Patients with primary luminal breast cancer (n = 123) in stage T1-3N0-2M0 who had not received neoadjuvant treatment were included in this study. Proteasome ChTL and CL activities were determined in the samples of tumor and adjacent tissues. The coefficients of chymotrypsin-like (kChTL) and caspase-like (kCL) proteasome activity were also calculated as the ratio of the corresponding activity in the tumor tissue to activity in the adjacent tissue. ChTL, CL, kChTL and kCL in the tissues of luminal A and B breast cancer with lymphogenic metastasis were compared, and their association with hematogenous metastasis was evaluated. On the one hand, CL activity of proteasomes increased in luminal A breast cancer with extensive lymphogenic metastasis (N2), on the other hand it decreased in the luminal B subtype of cancer. The ratio of proteasomal activity in the tumor and adjacent tissues plays a significant role in the hematogenic pathway of breast cancer progression and is associated with poor metastatic-free survival.

  15. Luminal progenitors restrict their lineage potential during mammary gland development.

    Science.gov (United States)

    Rodilla, Veronica; Dasti, Alessandro; Huyghe, Mathilde; Lafkas, Daniel; Laurent, Cécile; Reyal, Fabien; Fre, Silvia

    2015-02-01

    The hierarchical relationships between stem cells and progenitors that guide mammary gland morphogenesis are still poorly defined. While multipotent basal stem cells have been found within the myoepithelial compartment, the in vivo lineage potential of luminal progenitors is unclear. Here we used the expression of the Notch1 receptor, previously implicated in mammary gland development and tumorigenesis, to elucidate the hierarchical organization of mammary stem/progenitor cells by lineage tracing. We found that Notch1 expression identifies multipotent stem cells in the embryonic mammary bud, which progressively restrict their lineage potential during mammary ductal morphogenesis to exclusively generate an ERαneg luminal lineage postnatally. Importantly, our results show that Notch1-labelled cells represent the alveolar progenitors that expand during pregnancy and survive multiple successive involutions. This study reveals that postnatal luminal epithelial cells derive from distinct self-sustained lineages that may represent the cells of origin of different breast cancer subtypes.

  16. Human Mammary Luminal Epithelial Cells Contain Progenitors to Myoepithelial Cells

    Energy Technology Data Exchange (ETDEWEB)

    Pechoux, Christine; Gudjonsson, Thorarinn; Ronnov-Jessen, Lone; Bissell, Mina J; Petersen, Ole

    1999-02-01

    The origin of the epithelial and myoepithelial cells in the human breast has not been delineated. In this study we have addressed whether luminal epithelial cells and myoepithelial cells are vertically connected, i.e., whether one is the precursor for the other. We used a primary culture assay allowing preservation of basic phenotypic traits of luminal epithelial and myoepithelial cells in culture. The two cell types were then separated immunomagnetically using antibodies directed against lineage-specific cell surface antigens into at best 100% purity. The cellular identity was ascertained by cytochemistry, immunoblotting, and 2-D gel electrophoresis. Luminal epithelial cells were identified by strong expression of cytokeratins 18 and 19 while myoepithelial cells were recognized by expression of vimentin and {alpha}-smooth muscle actin. We used a previously devised culture medium (CDM4) that allows vigorous expansion of proliferative myoepithelial cells and also devised a medium (CDM6) that allowed sufficient expansion of differentiated luminal epithelial cells based on addition of hepatocyte growth factor/scatter factor. The two different culture media supported each lineage for at least five passages without signs of interconversion. We used parallel cultures where we switched culture media, thus testing the ability of each lineage to convert to the other. Whereas the myoepithelial lineage showed no signs of interconversion, a subset of luminal epithelial cells, gradually, but distinctly, converted to myoepithelial cells. We propose that in the mature human breast, it is the luminal epithelial cell compartment that gives rise to myoepithelial cells rather than the other way around.

  17. Early ERPs to faces: aging, luminance and individual differences

    Directory of Open Access Journals (Sweden)

    Magdalena Maria Bieniek

    2013-05-01

    Full Text Available Recently, Rousselet et al. reported a 1 ms/year delay in visual processing speed in a sample of healthy aged 62 subjects (Frontiers in Psychology 2010, 1:19. Here, we replicate this finding in an independent sample of 59 subjects and investigate the contribution of optical factors (pupil size and luminance to the age-related slowdown and to individual differences in visual processing speed. We conducted two experiments. In experiment 1 we recorded EEG from subjects aged 18-79. Subjects viewed images of faces and phase scrambled noise textures under nine luminance conditions, ranging from 0.59 to 60.8 cd/m2. We manipulated luminance using neutral density filters. In experiment 2, 10 young subjects (age <35 viewed similar stimuli through pinholes ranging from 1 to 5 mm. In both experiments, subjects were tested twice. We found a 1 ms/year slowdown in visual processing that was independent of luminance. Aging effects became visible around 125 ms post-stimulus and did not affect the onsets of the face-texture ERP differences. Furthermore, luminance modulated the entire ERP time-course from 60 to 500 ms. Luminance effects peaked in the N170 time window and were independent of age. Importantly, senile miosis and individual differences in pupil size did not account for aging differences and inter-subject variability in processing speed. The pinhole manipulation also failed to match the ERPs of old subjects to those of young subjects. Overall, our results strongly suggest that early ERPs to faces (<200 ms are delayed by aging and that these delays are of cortical, rather than optical origin. Our results also demonstrate that even late ERPs to faces are modulated by low-level factors.

  18. Infrared thermography

    CERN Document Server

    Meola, Carosena

    2012-01-01

    This e-book conveys information about basic IRT theory, infrared detectors, signal digitalization and applications of infrared thermography in many fields such as medicine, foodstuff conservation, fluid-dynamics, architecture, anthropology, condition monitoring, non destructive testing and evaluation of materials and structures.

  19. A Blind Pilot: Who is a Super-Luminal Observer?

    Directory of Open Access Journals (Sweden)

    Rabounski D.

    2008-04-01

    Full Text Available This paper discusses the nature of a hypothetical super-luminal observer who, as well as a real (sub-light speed observer, perceives the world by light waves. This consideration is due to that fact that the theory of relativity permits different frames of reference, including light-like and super-luminal reference frames. In analogy with a blind pilot on board a supersonic jet aeroplane (or missile, perceived by blind people, it is concluded that the light barrier is observed in the framework of only the light signal exchange experiment.

  20. A robust morphological classification of high-redshift galaxies using support vector machines on seeing limited images. II. Quantifying morphological k-correction in the COSMOS field at 1 < z < 2: Ks band vs. I band

    Science.gov (United States)

    Huertas-Company, M.; Tasca, L.; Rouan, D.; Pelat, D.; Kneib, J. P.; Le Fèvre, O.; Capak, P.; Kartaltepe, J.; Koekemoer, A.; McCracken, H. J.; Salvato, M.; Sanders, D. B.; Willott, C.

    2009-04-01

    Context: Morphology is the most accessible tracer of galaxies physical structure, but its interpretation in the framework of galaxy evolution still remains problematic. Its quantification at high redshift requires deep high-angular resolution imaging, which is why space data (HST) are usually employed. At z > 1, the HST visible cameras however probe the UV flux, which is dominated by the emission of young stars, which could bias the estimated morphologies towards late-type systems. Aims: In this paper we quantify the effects of this morphological k-correction at 1 Methods: In Paper I we presented a new non-parametric method of quantifying morphologies of galaxies on seeing-limited images based on support vector machines. Here we use this method to classify ~50 000 Ks selected galaxies in the COSMOS area observed with WIRCam at CFHT. We use a 10-dimensional volume, including 5 morphological parameters, and other characteristics of galaxies such as luminosity and redshift. The obtained classification is used to investigate the redshift distributions and number counts per morphological type up to z ~ 2 and to compare them to the results obtained with HST/ACS in the I-band on the same objects. We associate to every galaxy with Ks find less early-type galaxies than the Ks-band one by a factor ~1.5, which might be a consequence of morphological k-correction effects. Conclusions: We argue therefore that studies based on I-band HST/ACS classifications at z > 1 could be underestimating the elliptical population. Using our method in a Ks ≤ 21.5 magnitude-limited sample, we observe that the fraction of the early-type population is (21.9% ± 8%) at z ~ 1.5-2 and (32.0% ± 5%) at the present time. We will discuss the evolution of the fraction of galaxies in types from volume-limited samples in a forthcoming paper. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des

  1. Profile of a Growing Urban School: The Lumin Experience

    Science.gov (United States)

    Ford, Terry

    2015-01-01

    This fairytale-come-true began with an idealistic public school teacher just out of college who lived in the neighborhood of her students. In stages, working with a community organizing group consisting mainly of concerned parents, Terry Ford founded what is now called Lumin Education, a network of campuses serving more than six hundred children…

  2. Chromatic and luminance contrast sensitivity in fullterm and preterm infants

    Science.gov (United States)

    Bosworth, Rain G.; Dobkins, Karen R.

    2010-01-01

    In order to investigate the contributions of visual experience vs. preprogrammed mechanisms on visual development, the current study compared contrast sensitivity in preterm vs. fullterm infants. If development is tied to time since conception, preterm infants should match the developmental trajectories of fullterm infants when plotted in postterm age. By contrast, if development is influenced by visual experience, preterm and fullterm infants should match when plotted in postnatal age. Luminance (light/dark) and chromatic (red/green) contrast sensitivities (CS) were measured in 25 preterm (born, on average, 6.6 weeks early) and 77 fullterm infants, between 1 and 6 months postterm. In the first few months, luminance CS was found to be predicted by postterm age, suggesting that preprogrammed development is sufficient to account for luminance CS. By contrast, chromatic CS exceeded that predicted by postterm age, which suggests that time since birth confers a benefit on chromatic CS. The preterms’ 6.6 weeks of additional time since birth is roughly equivalent to 3.7 weeks of development in chromatic CS. In sum, these results suggest that chromatic CS is more influenced by early postnatal visual experience than luminance CS, which may have implications for development of parvocellular and magnocellular pathways. PMID:20055548

  3. A luminal flavoprotein in endoplasmic reticulum-associated degradation

    DEFF Research Database (Denmark)

    Riemer, Jan; Appenzeller-Herzog, Christian; Johansson, Linda

    2009-01-01

    The quality control system of the endoplasmic reticulum (ER) discriminates between native and nonnative proteins. The latter are degraded by the ER-associated degradation (ERAD) pathway. Whereas many cytosolic and membrane components of this system are known, only few luminal players have been id...

  4. Luminance compensation for AMOLED displays using integrated MIS sensors

    Science.gov (United States)

    Vygranenko, Yuri; Fernandes, Miguel; Louro, Paula; Vieira, Manuela

    2017-05-01

    Active-matrix organic light-emitting diodes (AMOLEDs) are ideal for future TV applications due to their ability to faithfully reproduce real images. However, pixel luminance can be affected by instability of driver TFTs and aging effect in OLEDs. This paper reports on a pixel driver utilizing a metal-insulator-semiconductor (MIS) sensor for luminance control of the OLED element. In the proposed pixel architecture for bottom-emission AMOLEDs, the embedded MIS sensor shares the same layer stack with back-channel etched a Si:H TFTs to maintain the fabrication simplicity. The pixel design for a large-area HD display is presented. The external electronics performs image processing to modify incoming video using correction parameters for each pixel in the backplane, and also sensor data processing to update the correction parameters. The luminance adjusting algorithm is based on realistic models for pixel circuit elements to predict the relation between the programming voltage and OLED luminance. SPICE modeling of the sensing part of the backplane is performed to demonstrate its feasibility. Details on the pixel circuit functionality including the sensing and programming operations are also discussed.

  5. luminous transmittance and phase transition temperature of vo2:ce ...

    African Journals Online (AJOL)

    nb

    A two-step increase in transmittance observed in the cooling loop in pure VO2 was found to be suppressed by cerium inclusion. Keywords: vanadium dioxide, luminous transmittance, phase transition temperature. INTRODUCTION. Discovery of novel behavior of vanadium dioxide to undergo a metal-to-insulator phase.

  6. The predetermination of the luminance in tunnel entrances at day.

    NARCIS (Netherlands)

    Schreuder, D.A. & Oud, H.J.C.

    1988-01-01

    In tunnel lighting practice, only the scatter in the eye, in the windscreen of the car, and in the atmosphere need to be taken into account. For all practical day- time conditions, the required luminance in any portion of the tunnel can be assessed as being a constant fraction of this sum-

  7. Isolation and characterization of endometrial luminal epithelial and ...

    African Journals Online (AJOL)

    Isolation and characterization of endometrial luminal epithelial and stromal cells in vitro. ... Endometrial lining were digested in trypsin, collagenase and bovine serum albumin dissolved in Hanks balanced solution. The cells were seeded into a 24-well plate at a concentration of 5 × 105 per well, while some were snap ...

  8. Astronomy. ASASSN-15lh: A highly super-luminous supernova.

    Science.gov (United States)

    Dong, Subo; Shappee, B J; Prieto, J L; Jha, S W; Stanek, K Z; Holoien, T W-S; Kochanek, C S; Thompson, T A; Morrell, N; Thompson, I B; Basu, U; Beacom, J F; Bersier, D; Brimacombe, J; Brown, J S; Bufano, F; Chen, Ping; Conseil, E; Danilet, A B; Falco, E; Grupe, D; Kiyota, S; Masi, G; Nicholls, B; Olivares E, F; Pignata, G; Pojmanski, G; Simonian, G V; Szczygiel, D M; Woźniak, P R

    2016-01-15

    We report the discovery of ASASSN-15lh (SN 2015L), which we interpret as the most luminous supernova yet found. At redshift z = 0.2326, ASASSN-15lh reached an absolute magnitude of Mu ,AB = -23.5 ± 0.1 and bolometric luminosity Lbol = (2.2 ± 0.2) × 10(45) ergs s(-1), which is more than twice as luminous as any previously known supernova. It has several major features characteristic of the hydrogen-poor super-luminous supernovae (SLSNe-I), whose energy sources and progenitors are currently poorly understood. In contrast to most previously known SLSNe-I that reside in star-forming dwarf galaxies, ASASSN-15lh appears to be hosted by a luminous galaxy (MK ≈ -25.5) with little star formation. In the 4 months since first detection, ASASSN-15lh radiated (1.1 ± 0.2) × 10(52) ergs, challenging the magnetar model for its engine. Copyright © 2016, American Association for the Advancement of Science.

  9. Gastric luminal epidermal growth factor is affected by diet

    African Journals Online (AJOL)

    intragastric epidermal growth factor level, diet and intragastric pH. Setting and subjects. A dietary survey was co-ordinated with studies of gastric luminal epidermal growth factor and gastric fluid pH in 120 rural Transkeians. Results. Gastric .... Playford RJ, Marchbank T, Calnan DP, et at. Epidermal growth factor is digested to ...

  10. Gastric luminal epidermal growth factor is affected by diet | Iputo ...

    African Journals Online (AJOL)

    Objective. Diet is an area of major interest to those investigating the causes of cancer of the oesophagus in the Transkei. This study looked at the associations between intragastric epidermal growth factor level, diet and intragastric pH. Setting and subjects. A dietary survey was co-ordinated with studies of gastric luminal ...

  11. Reproducibility of airway luminal size in asthma measured by HRCT.

    Science.gov (United States)

    Brown, Robert H; Henderson, Robert J; Sugar, Elizabeth A; Holbrook, Janet T; Wise, Robert A

    2017-10-01

    Brown RH, Henderson RJ, Sugar EA, Holbrook JT, Wise RA, on behalf of the American Lung Association Airways Clinical Research Centers. Reproducibility of airway luminal size in asthma measured by HRCT. J Appl Physiol 123: 876-883, 2017. First published July 13, 2017; doi:10.1152/japplphysiol.00307.2017.-High-resolution CT (HRCT) is a well-established imaging technology used to measure lung and airway morphology in vivo. However, there is a surprising lack of studies examining HRCT reproducibility. The CPAP Trial was a multicenter, randomized, three-parallel-arm, sham-controlled 12-wk clinical trial to assess the use of a nocturnal continuous positive airway pressure (CPAP) device on airway reactivity to methacholine. The lack of a treatment effect of CPAP on clinical or HRCT measures provided an opportunity for the current analysis. We assessed the reproducibility of HRCT imaging over 12 wk. Intraclass correlation coefficients (ICCs) were calculated for individual airway segments, individual lung lobes, both lungs, and air trapping. The ICC [95% confidence interval (CI)] for airway luminal size at total lung capacity ranged from 0.95 (0.91, 0.97) to 0.47 (0.27, 0.69). The ICC (95% CI) for airway luminal size at functional residual capacity ranged from 0.91 (0.85, 0.95) to 0.32 (0.11, 0.65). The ICC measurements for airway distensibility index and wall thickness were lower, ranging from poor (0.08) to moderate (0.63) agreement. The ICC for air trapping at functional residual capacity was 0.89 (0.81, 0.94) and varied only modestly by lobe from 0.76 (0.61, 0.87) to 0.95 (0.92, 0.97). In stable well-controlled asthmatic subjects, it is possible to reproducibly image unstimulated airway luminal areas over time, by region, and by size at total lung capacity throughout the lungs. Therefore, any changes in luminal size on repeat CT imaging are more likely due to changes in disease state and less likely due to normal variability.NEW & NOTEWORTHY There is a surprising lack of

  12. SPECTRAL AND SPATIAL SELECTIVITY OF LUMINANCE VISION IN REEF FISH

    Directory of Open Access Journals (Sweden)

    Ulrike E Siebeck

    2014-09-01

    Full Text Available Luminance vision has high spatial resolution and is used for form vision and texture discrimination. In humans, birds and bees luminance channel is spectrally selective – it depends on the signals of the long-wavelength sensitive photoreceptors (bees or on the sum of long- and middle- wavelength sensitive cones (humans, but not on the signal of the short-wavelength sensitive (blue photoreceptors. The reasons of such selectivity are not fully understood. The aim of this study is to reveal the inputs of cone signals to high resolution luminance vision in reef fish. 16 freshly caught damselfish, Pomacentrus amboinensis, were trained to discriminate stimuli differing either in their colour or in their fine patterns (stripes vs. cheques. Three colours (‘bright green’, ‘dark green’ and ‘blue’ were used to create two sets of colour and two sets of pattern stimuli. The ‘bright green’ and ‘dark green’ were similar in their chromatic properties for fish, but differed in their lightness; the ‘dark green’ differed from ‘blue’ in the signal for the blue cone, but yielded similar signals in the long-wavelength and middle-wavelength cones. Fish easily learned to discriminate ‘bright green’ from ‘dark green’ and ‘dark green’ from ‘blue’ stimuli. Fish also could discriminate the fine patterns created from ‘dark green’ and ‘bright green’. However, fish failed to discriminate fine patterns created from ‘blue’ and ‘dark green’ colours, i.e. the colours that provided contrast for the blue-sensitive photoreceptor, but not for the long-wavelength sensitive one. High resolution luminance vision in damselfish, Pomacentrus amboinensis, does not have input from the blue-sensitive cone, which may indicate that the spectral selectivity of luminance channel is a general feature of visual processing in both aquatic and terrestrial animals.

  13. A generalized model for luminance prediction in a bottom-lit backlight with cold cathode fluorescent lamps

    Science.gov (United States)

    Chang, Jee-Gong; Yang, Po-Hua

    2006-11-01

    This paper proposes a generalized model to predict the luminance of a bottom-lit backlight based on analytical estimates of the luminous flux input provided by a cold cathode fluorescent lamp (CCFL). The respective influences of the CCFL half-angle, the CCFL luminance decay factor, the luminance cone angle ratio and the luminance peak offset are discussed. The analytical results reveal that the CCLF half-angle has a more significant effect on the luminous flux and the backlight luminance than the CCFL luminance decay factor. In addition, when the luminance cone angle ratio is adjusted by changing the cone angle in one direction while maintaining the cone angle in the other as a constant, the luminance level is found to be higher when the luminance distribution has a circular cross section at the half-luminance peak rather than an elliptical cross section. Conversely, when the luminance cone angle ratio is adjusted under the condition that the cross-sectional area of the luminance distribution at the half-luminance peak remains constant, the luminance level is found to be higher for an elliptical cross section than for a circular cross section. Finally, the luminance level decreases more rapidly in a specific direction if the luminance cone angle in this direction is smaller than that in the other and the luminance peak offset increases coincidently in the same direction.

  14. Densities, cellulases, alginate and pectin lyases of luminous and other heterotrophic bacteria associated with marine algae

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaiah, N.; Chandramohan, D.

    enzymes. No luminous bacteria examined produced cellulases, but both V. harveyi and V. fischeri strains produced substantial amounts of alginate and pectin lyases. In contrast, cellulase activities were pronounced in non-luminous vibrio, pseudomonad...

  15. The design and capabilities of the EXIST optical and infra-red telescope (IRT)

    Science.gov (United States)

    Kutyrev, A. S.; Moseley, S. H.; Golisano, C.; Gong, Q.; Allen, B. T.; Gehrels, N.; Grindlay, J. E.; Hong, J. S.; Woodgate, B. E.

    2010-07-01

    The Infra-Red Telescope is a critical element of the EXIST (Energetic X-Ray Imaging Survey Telescope) observatory. The primary goal of the IRT is to obtain photometric and spectroscopic measurements of high redshift (>=6) gamma ray reaching to the epoque of reionization. The photometric and spectral capabilities of the IRT will allow to use GRB afterglow as probes of the composition and ionization state of the intergalactic medium of the young universe. A prompt follow up (within three minutes) of the transient discovered by the EXIST makes IRT a unique tool for detection and study of these events in the infrared and optical wavelength, which is particularly valuable at wavelengths unavailable to the ground based observatories. We present the results of the mission study development on the IRT as part of the EXIST observatory.

  16. Near-infrared SN Ia Cosmology

    Science.gov (United States)

    Avelino, Arturo; Kirshner, Robert; Mandel, Kaisey; Challis, Peter; Friedman, Andrew; RAISIN Team

    2018-01-01

    Observations of SN Ia in the near infrared (NIR) are a promising way to construct an accurate cosmic expansion history to constrain the properties of dark energy. SN Ia are more nearly standard candles in NIR than in optical bands, while dust absorption is less of a problem at NIR wavelengths. This allows us to investigate the dark energy properties in a way that is less sensitive to systematic errors due to the variations in the intrinsic brightness of SN Ia or the properties of dust in their host galaxies. In this talk, I present preliminary results from our RAISIN 1 (HST GO-13046) and RAISIN 2 (HST GO-14216) programs with the Hubble Space Telescope, where we have constructed a Hubble diagram combining optical + NIR photometric data using a sample of low and high redshift SN Ia. I will discuss our current results, challenges, and the advantage of using optical + NIR data to derive accurate cosmic distances and improve knowledge of the dark energy equation of state. This research is supported by NSF grants AST-156854 and AST-1211196.

  17. Appraisal of the quality of public lighting based on road surface luminance and glare.

    NARCIS (Netherlands)

    Boer, J.B. Burghout, F. & Heemskerck Veeckens, J.F.T. van

    1959-01-01

    Conclusions from earlier investigations indicating an average luminance of 2 cd/m 2 as necessary for dense traffic were confirmed by appraisals of luminance level and visibility trials. The colour of the light influences the visibility as well as the appraisal of luminance level, pattern and

  18. 10 CFR 30.19 - Self-luminous products containing tritium, krypton-85, or promethium-147.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Self-luminous products containing tritium, krypton-85, or... DOMESTIC LICENSING OF BYPRODUCT MATERIAL Exemptions § 30.19 Self-luminous products containing tritium... transfer for sale or distribution self-luminous products containing tritium, krypton-85, or promethium-147...

  19. File list: ALL.Brs.50.AllAg.Luminal_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Brs.50.AllAg.Luminal_cells mm9 All antigens Breast Luminal cells SRX213395,SRX2...13418,SRX213398,SRX213416 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Brs.50.AllAg.Luminal_cells.bed ...

  20. File list: ALL.Brs.10.AllAg.Luminal_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  1. File list: His.Brs.10.AllAg.Luminal_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  2. File list: ALL.Brs.05.AllAg.Luminal_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Brs.05.AllAg.Luminal_cells mm9 All antigens Breast Luminal cells SRX213395,SRX2...13398,SRX213418,SRX213416 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Brs.05.AllAg.Luminal_cells.bed ...

  3. File list: ALL.Brs.20.AllAg.Luminal_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  4. File list: His.Brs.20.AllAg.Luminal_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  5. File list: His.Brs.50.AllAg.Luminal_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  6. File list: His.Brs.05.AllAg.Luminal_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  7. Infrared Camera

    Science.gov (United States)

    1997-01-01

    A sensitive infrared camera that observes the blazing plumes from the Space Shuttle or expendable rocket lift-offs is capable of scanning for fires, monitoring the environment and providing medical imaging. The hand-held camera uses highly sensitive arrays in infrared photodetectors known as quantum well infrared photo detectors (QWIPS). QWIPS were developed by the Jet Propulsion Laboratory's Center for Space Microelectronics Technology in partnership with Amber, a Raytheon company. In October 1996, QWIP detectors pointed out hot spots of the destructive fires speeding through Malibu, California. Night vision, early warning systems, navigation, flight control systems, weather monitoring, security and surveillance are among the duties for which the camera is suited. Medical applications are also expected.

  8. Straightness as a cue for luminance edge interpretation.

    Science.gov (United States)

    Logvinenko, Alexander D; Adelson, Edward H; Ross, Deborah A; Somers, David

    2005-01-01

    In order to determine the reflectance of a surface, it is necessary to discount luminance changes produced by illumination variation, a process that requires the visual system to respond differently to luminance changes that are due to illumination and reflectance. It is known that various cues can be used in this process. By measuring the strength of lightness illusions, we find evidence that straightness is, used as a cue: When a boundary is straight rather than curved, it has a greater tendency to be discounted, as if it were an illumination edge. The strongest illusions occur when a boundary has high contrast and has multiple X-junctions that preserve a consistent contrast ratio.

  9. Infrared photoretinoscope.

    Science.gov (United States)

    Schaeffel, F; Farkas, L; Howland, H C

    1987-04-15

    A modification of the technique of photoretinoscopy is presented which allows measurement of the refractive state of the eye in noncooperative subjects and in very small eyes. Infrared light provided by high-output infrared LEDs permits measurement at large pupil sizes and thereby better resolution. Arrangement of the IR LEDs at different eccentricities from the optical axis of the video camera markedly increases the range of measurement. The current sensitivity for a measurement distance of 1.5 m in a human eye is +/- 0.3 diopter or better over a range of +/-5 diopters. Higher amounts of defocus can be better determined at shorter distances.

  10. Methods for Cultivation of Luminal Parasitic Protists of Clinical Importance

    Science.gov (United States)

    Clark, C. Graham; Diamond, Louis S.

    2002-01-01

    Cultivation of luminal protistan parasites has a long history. In this review we discuss the methods and media that are most widely used for the establishment and maintenance of the following organisms in culture: Entamoeba histolytica, Giardia intestinalis, Trichomonas vaginalis, Dientamoeba fragilis, Blastocystis hominis, and Balantidium coli. While cultivation is of limited importance in the diagnostic laboratory, it is essential to most research laboratories, and it is toward the latter that this review is primarily aimed. PMID:12097242

  11. Luminal leptin inhibits intestinal sugar absorption in vivo.

    Science.gov (United States)

    Iñigo, C; Patel, N; Kellett, G L; Barber, A; Lostao, M P

    2007-08-01

    We have previously demonstrated that leptin inhibits galactose absorption in rat intestinal everted rings and that leptin receptors are present in the apical membrane of the enterocytes. This adipocyte-derived hormone is also secreted by gastric mucosal cells and is able to reach the intestinal lumen. The goal of the present study was to prove whether luminal leptin acts on intestinal sugar absorption in vivo both at low (basal state) and high sugar concentration (post-prandial state). In vivo intestinal sugar absorption in rat was measured with recirculating and single-pass perfusion systems. Sugar disappearance in the perfusate was measured by radioactivity and biochemical methods. Luminal leptin effect on intestinal absorption mediated by sodium-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2) as well as intestinal permeability (mannitol absorption) was determined. Luminal leptin inhibited intestinal sugar absorption at low galactose concentrations, which indicates that leptin regulates SGLT1 activity in vivo. The inhibition was reversed in the absence of hormone in the intestinal lumen, suggesting that it was produced by post-translational regulation processes. At high luminal glucose concentrations, leptin also inhibited the phloretin-insensitive component of sugar absorption mediated by SGLT1. There was no significant effect on the apical GLUT2 component of absorption. Leptin did not modify in vivo intestinal permeability determined with (14)C-mannitol. These observations support the view that gastric leptin exerts a regulatory role on intestinal sugar absorption in the postprandial state by modifying the active component of absorption.

  12. Genome Sequence of Luminous Piezophile Photobacterium phosphoreum ANT-2200

    OpenAIRE

    Zhang, Sheng-Da; Barbe, Valérie; Garel, Marc; Zhang, Wei-Jia; Chen, Haitao; Santini, Claire-Lise; Murat, Dorothée; Jing, Hongmei; Zhao, Yuan; Lajus, Aurélie; Martini, Séverine; Pradel, Nathalie; Tamburini, Christian; Wu, Long-Fei

    2014-01-01

    Bacteria of the genus Photobacterium thrive worldwide in oceans and show substantially varied lifestyles, including free-living, commensal, pathogenic, symbiotic, and piezophilic. Here, we present the genome sequence of a luminous, piezophilic Photobacterium phosphoreum strain, ANT-2200, isolated from a water column at 2,200 m depth in the Mediterranean Sea. It is the first genomic sequence of the P. phosphoreum group. An analysis of the sequence provides insight into the adaptation of bacter...

  13. Dynamic encoding of natural luminance sequences by LGN bursts.

    Directory of Open Access Journals (Sweden)

    Nicholas A Lesica

    2006-07-01

    Full Text Available In the lateral geniculate nucleus (LGN of the thalamus, visual stimulation produces two distinct types of responses known as tonic and burst. Due to the dynamics of the T-type Ca(2+ channels involved in burst generation, the type of response evoked by a particular stimulus depends on the resting membrane potential, which is controlled by a network of modulatory connections from other brain areas. In this study, we use simulated responses to natural scene movies to describe how modulatory and stimulus-driven changes in LGN membrane potential interact to determine the luminance sequences that trigger burst responses. We find that at low resting potentials, when the T channels are de-inactivated and bursts are relatively frequent, an excitatory stimulus transient alone is sufficient to evoke a burst. However, to evoke a burst at high resting potentials, when the T channels are inactivated and bursts are relatively rare, prolonged inhibitory stimulation followed by an excitatory transient is required. We also observe evidence of these effects in vivo, where analysis of experimental recordings demonstrates that the luminance sequences that trigger bursts can vary dramatically with the overall burst percentage of the response. To characterize the functional consequences of the effects of resting potential on burst generation, we simulate LGN responses to different luminance sequences at a range of resting potentials with and without a mechanism for generating bursts. Using analysis based on signal detection theory, we show that bursts enhance detection of specific luminance sequences, ranging from the onset of excitatory sequences at low resting potentials to the offset of inhibitory sequences at high resting potentials. These results suggest a dynamic role for burst responses during visual processing that may change according to behavioral state.

  14. Luminous pre-main sequence stars in the LMC?

    NARCIS (Netherlands)

    Lamers, HJGLM; Beaulieu, JP

    We report the serendipitous discovery of seven luminous irregular variables in the LMC by the EROS project. The stars have V similar or equal to 15(m) to 17(m), (B(E) - R(E)) similar or equal to 0(m), and vary by about 0.4(m) on timescales of 10 to 40 days. The variations in B(E) and R(E) are about

  15. Luminous blue variables and the fates of very massive stars.

    Science.gov (United States)

    Smith, Nathan

    2017-10-28

    Luminous blue variables (LBVs) had long been considered massive stars in transition to the Wolf-Rayet (WR) phase, so their identification as progenitors of some peculiar supernovae (SNe) was surprising. More recently, environment statistics of LBVs show that most of them cannot be in transition to the WR phase after all, because LBVs are more isolated than allowed in this scenario. Additionally, the high-mass H shells around luminous SNe IIn require that some very massive stars above 40  M ⊙ die without shedding their H envelopes, and the precursor outbursts are a challenge for understanding the final burning sequences leading to core collapse. Recent evidence suggests a clear continuum in pre-SN mass loss from super-luminous SNe IIn, to regular SNe IIn, to SNe II-L and II-P, whereas most stripped-envelope SNe seem to arise from a separate channel of lower-mass binary stars rather than massive WR stars.This article is part of the themed issue 'Bridging the gap: from massive stars to supernovae'. © 2017 The Author(s).

  16. Night sky luminance under clear sky conditions: Theory vs. experiment

    Science.gov (United States)

    Kocifaj, Miroslav

    2014-05-01

    Sky glow is caused by both natural phenomena and factors of anthropogenic origin, and of the latter ground-based light sources are the most important contributors for they emit the spatially linked spectral radiant intensity distribution of artificial light sources, which are further modulated by local atmospheric optics and perceived as the diffuse light of a night sky. In other words, sky glow is closely related to a city's shape and pattern of luminaire distribution, in practical effect an almost arbitrary deployment of random orientation of heterogeneous electrical light sources. Thus the luminance gradation function measured in a suburban zone or near the edges of a city is linked to the City Pattern or vice versa. It is shown that clear sky luminance/radiance data recorded in an urban area can be used to retrieve the bulk luminous/radiant intensity distribution if some a-priori information on atmospheric aerosols is available. For instance, the single scattering albedo of aerosol particles is required under low turbidity conditions, as demonstrated on a targeted experiment in the city of Frýdek-Mistek. One of the main advantages of the retrieval method presented in this paper is that the single scattering approximation is satisfactorily accurate in characterizing the light field near the ground because the dominant contribution to the sky glow has originated from beams propagated along short optical paths.

  17. Early ERPs to faces: aging, luminance, and individual differences

    Science.gov (United States)

    Bieniek, Magdalena M.; Frei, Luisa S.; Rousselet, Guillaume A.

    2013-01-01

    Recently, Rousselet et al. reported a 1 ms/year delay in visual processing speed in a sample of healthy aged 62 subjects (Frontiers in Psychology 2010, 1:19). Here, we replicate this finding in an independent sample of 59 subjects and investigate the contribution of optical factors (pupil size and luminance) to the age-related slowdown and to individual differences in visual processing speed. We conducted two experiments. In experiment 1 we recorded EEG from subjects aged 18–79. Subjects viewed images of faces and phase scrambled noise textures under nine luminance conditions, ranging from 0.59 to 60.8 cd/m2. We manipulated luminance using neutral density filters. In experiment 2, 10 young subjects (age miosis and individual differences in pupil size did not account for aging differences and inter-subject variability in processing speed. The pinhole manipulation also failed to match the ERPs of old subjects to those of young subjects. Overall, our results strongly suggest that early ERPs to faces (<200 ms) are delayed by aging and that these delays are of cortical, rather than optical origin. Our results also demonstrate that even late ERPs to faces are modulated by low-level factors. PMID:23717297

  18. Infrared Thermometers

    Science.gov (United States)

    Schaefers, John

    2006-01-01

    An infrared (IR) thermometer lab offers the opportunity to give science students a chance to measure surface temperatures, utilizing off-the-shelf technology. Potential areas of study include astronomy (exoplanets), electromagnetic spectrum, chemistry, evaporation rates, anatomy, crystal formation, and water or liquids. This article presents one…

  19. Variations on a classical theme: On the formal relationship between magnitudes per square arcsecond and luminance

    Directory of Open Access Journals (Sweden)

    Salvador Bará

    2017-12-01

    Full Text Available The formal link between magnitudes per square arcsecond and luminance is discussed in this paper. Directly related to the human visual system, luminance is defined in terms of the spectral radiance of the source, weighted by the CIE V(l luminous efficiency function, and scaled by the 683 lm/W luminous efficacy constant. In consequence, any exact and spectrum-independent relationship between luminance and magnitudes per square arcsecond requires that the last ones be measured precisely in the CIE V(l band. The luminance value corresponding to mVC=0 (zero-point of the CIE V(l magnitude scale depends on the reference source chosen for the definition of the magnitude system. Using absolute AB magnitudes, the zero point luminance of the CIE V(l photometric band is 10.96 x 104 cd·m-2.

  20. Infrared retina

    Science.gov (United States)

    Krishna, Sanjay [Albuquerque, NM; Hayat, Majeed M [Albuquerque, NM; Tyo, J Scott [Tucson, AZ; Jang, Woo-Yong [Albuquerque, NM

    2011-12-06

    Exemplary embodiments provide an infrared (IR) retinal system and method for making and using the IR retinal system. The IR retinal system can include adaptive sensor elements, whose properties including, e.g., spectral response, signal-to-noise ratio, polarization, or amplitude can be tailored at pixel level by changing the applied bias voltage across the detector. "Color" imagery can be obtained from the IR retinal system by using a single focal plane array. The IR sensor elements can be spectrally, spatially and temporally adaptive using quantum-confined transitions in nanoscale quantum dots. The IR sensor elements can be used as building blocks of an infrared retina, similar to cones of human retina, and can be designed to work in the long-wave infrared portion of the electromagnetic spectrum ranging from about 8 .mu.m to about 12 .mu.m as well as the mid-wave portion ranging from about 3 .mu.m to about 5 .mu.m.

  1. Detection of Perturbation in Chromatic and Luminance-Defined Lines and Square-Waves

    Directory of Open Access Journals (Sweden)

    R.J Sharman

    2014-08-01

    Full Text Available The composition of a stimulus may affect how cues are combined. A thin luminance ring surrounding a uniform chromatic test facilitates contrast detection as much as a uniform luminance pedestal (Cole, Stromeyer & Kronauer, 1990, JOSA A, 7(1, 128-140. This could suggest that there is a specific facilitatory relationship between luminance lines and chromatic edges that is not present in other combinations. Therefore, combining luminance lines and chromatic edges could also improve performance in edge detection tasks. Here we use a novel task, perturbation detection, target gratings were sinusoidally perturbed in space and subjects were asked to detect which of two stimuli was not straight. Perturbation thresholds, were measured for chromatic and luminance defined line and square-wave gratings alone and in combination. The introduction of a line mask produced increased thresholds in all conditions. However, the introduction of a chromatic square-wave mask improved perception of perturbation in luminance lines, whereas the introduction of a luminance defined square-wave mask has little effect on the perturbation thresholds for chromatic lines. This could suggest that when a luminance line is presented with a chromatic edge, such as the chromatic boundaries in a square-wave grating, the chromatic information becomes ‘tied’ to the luminance information. The perceived location of the chromatic edge may be determined by the location of the luminance line.

  2. LUMINOUS SATELLITES VERSUS DARK SUBHALOS: CLUSTERING IN THE MILKY WAY

    Energy Technology Data Exchange (ETDEWEB)

    Bozek, Brandon; Wyse, Rosemary F. G. [Physics and Astronomy Department, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Gilmore, Gerard, E-mail: bbozek@pha.jhu.edu [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2013-08-01

    The observed population of the Milky Way satellite galaxies offers a unique testing ground for galaxy formation theory on small scales. Our novel approach was to investigate the clustering of the known Milky Way satellite galaxies and to quantify the amount of substructure within their distribution using a two-point correlation function statistic in each of three spaces: configuration space, line-of-sight velocity space, and four-dimensional (4D) phase space. These results were compared to those for three sets of subhalos in the Via Lactea II cold dark matter (CDM) simulation defined to represent the luminous dwarfs. We found no evidence at a significance level above 2{sigma} of substructure within the distribution of the Milky Way satellite galaxies in any of the three spaces. The 'luminous' subhalo sets are more strongly clustered than are the Milky Way satellites in all three spaces and over a broader range of scales in 4D phase space. Each of the 'luminous' subhalo sets are clustered as a result of substructure within their line-of-sight velocity space distributions at greater than 3{sigma} significance, whereas the Milky Way satellite galaxies are randomly distributed in line-of-sight velocity space. While our comparison is with only one CDM simulation, the inconsistencies between the Milky Way satellite galaxies and the Via Lactea II subhalo sets for all clustering methods suggest a potential new 'small-scale' tension between CDM theory and the observed Milky Way satellites. Future work will obtain a more robust comparison between the observed Milky Way satellites and CDM theory by studying additional simulations.

  3. Clinical trials in luminal Crohn's disease: a historical perspective.

    Science.gov (United States)

    Hindryckx, Pieter; Baert, Filip; Hart, Ailsa; Armuzzi, Alessandro; Panès, Julian; Peyrin-Biroulet, Laurent

    2014-11-01

    It goes back to 1932 when Dr. Burrill Bernard Crohn and co-workers published their landmark paper, describing regional ileitis as a disease entity. However, clinical trial research has been developing rather slowly in luminal Crohn's disease. It took until the early seventies before the first randomized clinical trial was set up by the National Co-operative Crohn's Disease Study (NCCDS) group. Although the efforts of this group triggered a first wave of clinical trials in Crohn's disease, the lack of guidelines for conducting a clinical trial in this research area resulted in a variety of study designs and much criticism. Besides having a rather small sample size and a short follow-up time, they were often characterized by vague and subjective assessment of disease activity and treatment response. Following the advent of a new and very potent drug class in the late nineties, the anti-TNF agents, investigators started to re-think their study protocols and the first guidelines were set up by the regulatory authorities. Over the last 15years, clinical trials in luminal Crohn's disease have been evolving significantly. Inclusion criteria have been shifting from clinical scores such as Crohn's Disease Activity Index (CDAI) to more objective disease activity parameters such as biomarkers (C-reactive protein and faecal calprotectin) and endoscopic lesions. Primary endpoints have been developing from clinical response to corticosteroid-free remission and more ambitious end-points such as mucosal healing. In this paper, we will give a historical overview on clinical trials in luminal Crohn's disease, before and within the biologic era, and provide insight into how they have shaped our current understanding of trial designs in Crohn's disease. Copyright © 2014 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.

  4. The X-ray properties of z 6 luminous quasars

    Science.gov (United States)

    Nanni, R.; Vignali, C.; Gilli, R.; Moretti, A.; Brandt, W. N.

    2017-07-01

    We present a systematic analysis of X-ray archival data of all the 29 quasars (QSOs) at z> 5.5 observed so far with Chandra, XMM-Newton and Swift-XRT, including the most-distant quasar ever discovered, ULAS J1120+0641 (z = 7.08). This study allows us to place constraints on the mean spectral properties of the primordial population of luminous Type 1 (unobscured) quasars. Eighteen quasars are detected in the X-ray band, and we provide spectral-fitting results for their X-ray properties, while for the others we provide upper limits to their soft (0.5-2.0 keV) X-ray flux. We measured the power-law photon index and derived an upper limit to the column density for the five quasars (J1306+0356, J0100+2802, J1030+0524, J1148+5251, J1120+0641) with the best spectra (>30 net counts in the 0.5-7.0 keV energy range) and find that they are consistent with values from the literature and lower-redshift quasars. By stacking the spectra of ten quasars detected by Chandra in the redshift range 5.7 ≤ z ≤ 6.1 we find a mean X-ray power-law photon index of Γ = 1.92-0.27+0.28 and a neutral intrinsic absorption column density of NH ≤ 1023 cm-2. These results suggest that the X-ray spectral properties of luminous quasars have not evolved up to z ≈ 6. We also derived the optical-X-ray spectral slopes (αox) of our sample and combined them with those of previous works, confirming that αox strongly correlates with UV monochromatic luminosity at 2500 Å. These results strengthen the non-evolutionary scenario for the spectral properties of luminous active galactic nuclei (AGN).

  5. Color and luminance increment thresholds in poor readers.

    Science.gov (United States)

    Dain, Stephen J; Floyd, Richard A; Elliot, Robert T

    2008-01-01

    The hypotheses of a visual basis to reading disabilities in some children have centered around deficits in the visual processes displaying more transient responses to stimuli although hyperactivity in the visual processes displaying sustained responses to stimuli has also been proposed as a mechanism. In addition, there is clear evidence that colored lenses and/or colored overlays and/or colored backgrounds can influence performance in reading and/or may assist in providing comfortable vision for reading and, as a consequence, the ability to maintain reading for longer. As a consequence, it is surprising that the color vision of poor readers is relatively little studied. We assessed luminance increment thresholds and equi-luminous red-green and blue-yellow increment thresholds using a computer based test in central vision and at 10 degrees nasally employing the paradigm pioneered by King-Smith. We examined 35 poor readers (based on the Neale Analysis of Reading) and compared their performance with 35 normal readers matched for age and IQ. Poor readers produced similar luminance contrast thresholds for both foveal and peripheral presentation compared with normals. Similarly, chromatic contrast discrimination for the red/green stimuli was the same in normal and poor readers. However, poor readers had significantly lower thresholds/higher sensitivity for the blue/yellow stimuli, for both foveal and peripheral presentation, compared with normal readers. This hypersensitivity in blue-yellow discrimination may point to why colored lenses and overlays are often found to be effective in assisting many poor readers.

  6. Genome Sequence of Luminous Piezophile Photobacterium phosphoreum ANT-2200.

    Science.gov (United States)

    Zhang, Sheng-Da; Barbe, Valérie; Garel, Marc; Zhang, Wei-Jia; Chen, Haitao; Santini, Claire-Lise; Murat, Dorothée; Jing, Hongmei; Zhao, Yuan; Lajus, Aurélie; Martini, Séverine; Pradel, Nathalie; Tamburini, Christian; Wu, Long-Fei

    2014-04-17

    Bacteria of the genus Photobacterium thrive worldwide in oceans and show substantially varied lifestyles, including free-living, commensal, pathogenic, symbiotic, and piezophilic. Here, we present the genome sequence of a luminous, piezophilic Photobacterium phosphoreum strain, ANT-2200, isolated from a water column at 2,200 m depth in the Mediterranean Sea. It is the first genomic sequence of the P. phosphoreum group. An analysis of the sequence provides insight into the adaptation of bacteria to the deep-sea habitat.

  7. Comparison of luminance based metrics in different lighting conditions

    DEFF Research Database (Denmark)

    Wienold, J.; Kuhn, T.E.; Christoffersen, J.

    seven metrics CGI, modified DGI, DGP, Ev, average Luminance of the image Lavg, UGP and UGR are passing all statistical tests. DGP, CGI, DGI_mod and UGP have largest AUC and might be slightly more robust. The accuracy of the predictions of afore mentioned seven metrics for the disturbance by glare lies...... do the glare metrics describe the subjects’ disturbance by glare? We applied Spearman correlations, logistic regressions and an accuracy evaluation, based on an ROC-analysis. The results show that five of the twelve investigated metrics are failing at least one of the statistical tests. The other...

  8. The origin of the most luminous Planetary Nebulae

    Science.gov (United States)

    Galera-Rosillo, Rebeca; Corradi, Romano L. M.; Balick, Bruce; Kwitter, Karen; Mampaso, Antonio; García-Rojas, Jorge

    2017-10-01

    As part of a systematic effort to characterize the properties and progenitors of the most luminous planetary nebulae (PNe), we obtained a sample among the brightest PNe in two stellar systems of different metallicities: LMC (Z/Z⊙~0.5) and M31 (Z/Z⊙~1) by means of a combined effort with the VLT and the 10mGTC. Modelling of these data will allow us to infer the masses of the stellar progenitors, gaining insights into the controversial origin of the universal cutoff of the Planetary Nebulae Luminosity Function (PNLF).

  9. Polarized scattered light from self-luminous exoplanets. Three-dimensional scattering radiative transfer with ARTES

    Science.gov (United States)

    Stolker, T.; Min, M.; Stam, D. M.; Mollière, P.; Dominik, C.; Waters, L. B. F. M.

    2017-11-01

    Context. Direct imaging has paved the way for atmospheric characterization of young and self-luminous gas giants. Scattering in a horizontally-inhomogeneous atmosphere causes the disk-integrated polarization of the thermal radiation to be linearly polarized, possibly detectable with the newest generation of high-contrast imaging instruments. Aims: We aim to investigate the effect of latitudinal and longitudinal cloud variations, circumplanetary disks, atmospheric oblateness, and cloud particle properties on the integrated degree and direction of polarization in the near-infrared. We want to understand how 3D atmospheric asymmetries affect the polarization signal in order to assess the potential of infrared polarimetry for direct imaging observations of planetary-mass companions. Methods: We have developed a three-dimensional Monte Carlo radiative transfer code (ARTES) for scattered light simulations in (exo)planetary atmospheres. The code is applicable to calculations of reflected light and thermal radiation in a spherical grid with a parameterized distribution of gas, clouds, hazes, and circumplanetary material. A gray atmosphere approximation is used for the thermal structure. Results: The disk-integrated degree of polarization of a horizontally-inhomogeneous atmosphere is maximal when the planet is flattened, the optical thickness of the equatorial clouds is large compared to the polar clouds, and the clouds are located at high altitude. For a flattened planet, the integrated polarization can both increase or decrease with respect to a spherical planet which depends on the horizontal distribution and optical thickness of the clouds. The direction of polarization can be either parallel or perpendicular to the projected direction of the rotation axis when clouds are zonally distributed. Rayleigh scattering by submicron-sized cloud particles will maximize the polarimetric signal whereas the integrated degree of polarization is significantly reduced with micron

  10. Modeling The Most Luminous Supernova Associated with a Gamma-Ray Burst, SN 2011kl

    Science.gov (United States)

    Wang, Shan-Qin; Cano, Zach; Wang, Ling-Jun; Zheng, WeiKang; Dai, Zi-Gao; Filippenko, Alexei V.; Liu, Liang-Duan

    2017-12-01

    We study the most luminous known supernova (SN) associated with a gamma-ray burst (GRB), SN 2011kl. The photospheric velocity of SN 2011kl around peak brightness is 21,000 ± 7000 km s-1. Owing to different assumptions related to the light-curve (LC) evolution (broken or unbroken power-law function) of the optical afterglow of GRB 111209A, different techniques for the LC decomposition, and different methods (with or without a near-infrared contribution), three groups derived three different bolometric LCs for SN 2011kl. Previous studies have shown that the LCs without an early-time excess preferred a magnetar model, a magnetar+56Ni model, or a white dwarf tidal disruption event model rather than the radioactive heating model. On the other hand, the LC shows an early-time excess and dip that cannot be reproduced by the aforementioned models, and hence the blue-supergiant model was proposed to explain it. Here, we reinvestigate the energy sources powering SN 2011kl. We find that the two LCs without the early-time excess of SN 2011kl can be explained by the magnetar+56Ni model, and the LC showing the early excess can be explained by the magnetar+56Ni model taking into account the cooling emission from the shock-heated envelope of the SN progenitor, demonstrating that this SN might primarily be powered by a nascent magnetar.

  11. The luminous red nova M101-OT2015-1: a candidate for common envelope ejection

    Science.gov (United States)

    Blagorodnova, Nadejda; Kasliwal, Mansi M.; Kotak, Rubina

    2017-01-01

    Binary interaction is an important phase in the study of stellar evolution. Approximately 50% of O star population live in close binary systems as to allow interaction with the companion. Although massive binary progenitors have been associated with thermonuclear supernovae, stripped core collapse supernovae, cataclysmic variables, X-ray binaries, or the mind blowing massive binary black holes recently detected by LIGO, the exact evolutionary path followed by the system is still under debate. One of the critical phases is the common envelope (CE) phase, required to bring a long period binary into a much shorter orbit. Currently, this phase also represents a challenge for the current stellar evolution models. Given the uncertainty, observational constraints are valuable input to advance in this field. One particular class of transient objects, called Luminous Red Novae (LRNe), has been associated with the termination of the CE phase, when a total or partial ejection of the least bound layers of the primary star are expelled at the expense of decreasing the orbital energy of the system. In my talk I will discuss the results of 16 years of observations of M101-OT2015-1, a LRN in M101 galaxy. I will describe the progenitor star (system) and the main characteristics of the outburst. Finally, I will present the results of the evolution of its remnant in infrared wavelengths. Given the long time span of our observations, this event represents one of the best studied CE ejection candidate at extragalactic distances.

  12. Sky luminance distribution in Pamplona (Spain) during the summer period

    Science.gov (United States)

    Torres, J. L.; de Blas, M.; García, A.; Gracia, A.; de Francisco, A.

    2010-04-01

    In this work the outdoor daylight conditions in Pamplona (South Europe) during the summer period have been studied. The selected sky type (from fifteen standards) at a given moment is the one exhibiting the lowest RMSD when comparing the theoretical and experimental luminance distributions in the sky hemisphere. Two year data of luminance distribution registered every 10 min in 145 positions of the sky hemisphere have been used for selecting the sky type. The most frequent sky type in Pamplona is V.5 (cloudless polluted with a broad solar corona), with an occurrence of 29.5%. This result coincides with the one observed in a previous study in Athens. Six types of sky (V.5, IV.4, III.4, III.3, V.4 y II.2) out of the fifteen standards become practically the 80% of all the studied ones. Regarding a possible use in daylight climate studies, the frequency of occurrence of the fifteen types of sky for fourteen solar elevation intervals has been included.

  13. Effect of americium-241 on luminous bacteria. Role of peroxides.

    Science.gov (United States)

    Alexandrova, M; Rozhko, T; Vydryakova, G; Kudryasheva, N

    2011-04-01

    The effect of americium-241 ((241)Am), an alpha-emitting radionuclide of high specific activity, on luminous bacteria Photobacterium phosphoreum was studied. Traces of (241)Am in nutrient media (0.16-6.67 kBq/L) suppressed the growth of bacteria, but enhanced luminescence intensity and quantum yield at room temperature. Lower temperature (4 °C) increased the time of bacterial luminescence and revealed a stage of bioluminescence inhibition after 150 h of bioluminescence registration start. The role of conditions of exposure the bacterial cells to the (241)Am is discussed. The effect of (241)Am on luminous bacteria was attributed to peroxide compounds generated in water solutions as secondary products of radioactive decay. Increase of peroxide concentration in (241)Am solutions was demonstrated; and the similarity of (241)Am and hydrogen peroxide effects on bacterial luminescence was revealed. The study provides a scientific basis for elaboration of bioluminescence-based assay to monitor radiotoxicity of alpha-emitting radionuclides in aquatic solutions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Effect of americium-241 on luminous bacteria. Role of peroxides

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrova, M., E-mail: maka-alexandrova@rambler.r [Siberian Federal University, Svobodny 79, 660041 Krasnoyarsk (Russian Federation); Rozhko, T. [Siberian Federal University, Svobodny 79, 660041 Krasnoyarsk (Russian Federation); Vydryakova, G. [Institute of Biophysics SB RAS, Akademgorodok 50, 660036 Krasnoyarsk (Russian Federation); Kudryasheva, N. [Siberian Federal University, Svobodny 79, 660041 Krasnoyarsk (Russian Federation); Institute of Biophysics SB RAS, Akademgorodok 50, 660036 Krasnoyarsk (Russian Federation)

    2011-04-15

    The effect of americium-241 ({sup 241}Am), an alpha-emitting radionuclide of high specific activity, on luminous bacteria Photobacterium phosphoreum was studied. Traces of {sup 241}Am in nutrient media (0.16-6.67 kBq/L) suppressed the growth of bacteria, but enhanced luminescence intensity and quantum yield at room temperature. Lower temperature (4 {sup o}C) increased the time of bacterial luminescence and revealed a stage of bioluminescence inhibition after 150 h of bioluminescence registration start. The role of conditions of exposure the bacterial cells to the {sup 241}Am is discussed. The effect of {sup 241}Am on luminous bacteria was attributed to peroxide compounds generated in water solutions as secondary products of radioactive decay. Increase of peroxide concentration in {sup 241}Am solutions was demonstrated; and the similarity of {sup 241}Am and hydrogen peroxide effects on bacterial luminescence was revealed. The study provides a scientific basis for elaboration of bioluminescence-based assay to monitor radiotoxicity of alpha-emitting radionuclides in aquatic solutions. - Highlights: {yields} Am-241 in water solutions (A = 0.16-6.7 kBq/L) suppresses bacterial growth.{yields} Am-241 (A = 0.16-6.7 kBq/L) stimulate bacterial luminescence. {yields} Peroxides, secondary radiolysis products, cause increase of bacterial luminescence.

  15. Active Luminous Blue Variables in the Large Magellanic Cloud

    Science.gov (United States)

    Walborn, Nolan R.; Gamen, Roberto C.; Morrell, Nidia I.; Barbá, Rodolfo H.; Fernández Lajús, Eduardo; Angeloni, Rodolfo

    2017-07-01

    We present extensive spectroscopic and photometric monitoring of two famous and currently highly active luminous blue variables (LBVs) in the Large Magellanic Cloud (LMC), together with more limited coverage of three further, lesser known members of the class. R127 was discovered as an Ofpe/WN9 star in the 1970s but entered a classical LBV outburst in or about 1980 that is still in progress, thus enlightening us about the minimum state of such objects. R71 is currently the most luminous star in the LMC and continues to provide surprises, such as the appearance of [Ca II] emission lines, as its spectral type becomes unprecedentedly late. Most recently, R71 has developed inverse P Cyg profiles in many metal lines. The other objects are as follows: HDE 269582, now a “second R127” that has been followed from Ofpe/WN9 to A type in its current outburst; HDE 269216, which changed from late B in 2014 to AF in 2016, its first observed outburst; and R143 in the 30 Doradus outskirts. The light curves and spectroscopic transformations are correlated in remarkable detail and their extreme reproducibility is emphasized, both for a given object and among all of them. It is now believed that some LBVs proceed directly to core collapse. One of these unstable LMC objects may thus oblige in the near future, teaching us even more about the final stages of massive stellar evolution.

  16. The Highly Luminous Type Ibn Supernova ASASSN-14ms

    DEFF Research Database (Denmark)

    Vallely, P. J.; Prieto, J. L.; Stanek, K. Z.

    2018-01-01

    We present photometric and spectroscopic follow-up observations of the highly luminous Type Ibn supernova ASASSN-14ms, which was discovered on UT 2014-12-26.61 at $m_V \\sim 16.5$. With a peak absolute $V$-band magnitude brighter than $-20.5$, a peak bolometric luminosity of $1.7 \\times 10......^{44}$ ergs s$^{-1}$, and a total radiated energy of $2.1 \\times 10^{50}$ ergs, ASASSN-14ms is one of the most luminous Type Ibn supernovae yet discovered. In simple models, the most likely power source for this event is a combination of the radioactive decay of $^{56}$Ni and $^{56}$Co at late times.......6$) host galaxy SDSS J130408.52+521846.4 has an oxygen abundance below $12+\\log(O/H) \\lesssim 8.3$, a stellar mass of $M_* \\sim 2.6 \\times 10^8 M_{\\odot}$, and a star formation rate of $\\textrm{SFR} \\sim 0.02$ $M_{\\odot}$ yr$^{-1}$....

  17. Active Luminous Blue Variables in the Large Magellanic Cloud

    Energy Technology Data Exchange (ETDEWEB)

    Walborn, Nolan R. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Gamen, Roberto C.; Lajús, Eduardo Fernández [Instituto de Astrofísica de La Plata, CONICET–UNLP and Facultad de Ciencias Astronómicas y Geofísicas, UNLP, Paseo del Bosque s/n, La Plata (Argentina); Morrell, Nidia I. [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile); Barbá, Rodolfo H. [Departamento de Física y Astronomía, Universidad de La Serena, Cisternas 1200 Norte, La Serena (Chile); Angeloni, Rodolfo, E-mail: walborn@stsci.edu, E-mail: rgamen@fcaglp.unlp.edu.ar, E-mail: eflajus@fcaglp.unlp.edu.ar, E-mail: nmorrell@lco.cl, E-mail: rbarba@dfuls.cl, E-mail: rangelon@gemini.edu [Gemini Observatory, Colina El Pino, Casilla 603, La Serena (Chile)

    2017-07-01

    We present extensive spectroscopic and photometric monitoring of two famous and currently highly active luminous blue variables (LBVs) in the Large Magellanic Cloud (LMC), together with more limited coverage of three further, lesser known members of the class. R127 was discovered as an Ofpe/WN9 star in the 1970s but entered a classical LBV outburst in or about 1980 that is still in progress, thus enlightening us about the minimum state of such objects. R71 is currently the most luminous star in the LMC and continues to provide surprises, such as the appearance of [Ca ii] emission lines, as its spectral type becomes unprecedentedly late. Most recently, R71 has developed inverse P Cyg profiles in many metal lines. The other objects are as follows: HDE 269582, now a “second R127” that has been followed from Ofpe/WN9 to A type in its current outburst; HDE 269216, which changed from late B in 2014 to AF in 2016, its first observed outburst; and R143 in the 30 Doradus outskirts. The light curves and spectroscopic transformations are correlated in remarkable detail and their extreme reproducibility is emphasized, both for a given object and among all of them. It is now believed that some LBVs proceed directly to core collapse. One of these unstable LMC objects may thus oblige in the near future, teaching us even more about the final stages of massive stellar evolution.

  18. The Highly Luminous Type Ibn Supernova ASASSN-14ms

    DEFF Research Database (Denmark)

    Vallely, P. J.; Prieto, J. L.; Stanek, K. Z.

    2017-01-01

    ^{44}$ ergs s$^{-1}$, and a total radiated energy of $2.1 \\times 10^{50}$ ergs, ASASSN-14ms is one of the most luminous Type Ibn supernovae yet discovered. In simple models, the most likely power source for this event is a combination of the radioactive decay of $^{56}$Ni and $^{56}$Co at late times......We present photometric and spectroscopic follow-up observations of the highly luminous Type Ibn supernova ASASSN-14ms, which was discovered on UT 2014-12-26.61 at $m_V \\sim 16.5$. With a peak absolute $V$-band magnitude brighter than $-20.5$, a peak bolometric luminosity of $1.7 \\times 10...... and the interaction of supernova ejecta with the progenitor's circumstellar medium at early times, although we cannot rule out the possibility of a magnetar-powered light curve. The presence of a dense circumstellar medium is indicated by the intermediate-width He I features in the spectra. The faint ($m_g \\sim 21...

  19. No hot and luminous progenitor for Tycho's supernova

    Science.gov (United States)

    Woods, T. E.; Ghavamian, P.; Badenes, C.; Gilfanov, M.

    2017-11-01

    Type Ia supernovae have proven vital to our understanding of cosmology, both as standard candles and for their role in galactic chemical evolution; however, their origin remains uncertain. The canonical accretion model implies a hot and luminous progenitor that would ionize the surrounding gas out to a radius of 10-100 pc for 100,000 years after the explosion. Here, we report stringent upper limits on the temperature and luminosity of the progenitor of Tycho's supernova (SN 1572), determined using the remnant itself as a probe of its environment. Hot, luminous progenitors that would have produced a greater hydrogen ionization fraction than that measured at the radius of the present remnant ( 3 pc) can thus be excluded. This conclusively rules out steadily nuclear-burning white dwarfs (supersoft X-ray sources), as well as disk emission from a Chandrasekhar-mass white dwarf accreting approximately greater than 10-8 M⊙ yr-1 (recurrent novae; M⊙ is equal to one solar mass). The lack of a surrounding Strömgren sphere is consistent with the merger of a double white dwarf binary, although other more exotic scenarios may be possible.

  20. A method for selecting the CIE standard general sky model with regard to calculating luminance distributions

    Science.gov (United States)

    Ferraro, Vittorio; Marinelli, Valerio; Mele, Marilena

    2013-04-01

    It is known that the best predictions of sky luminances are obtainable by the CIE 15 standard skies model, but the predictions by this model need knowledge of the measured luminance distributions themselves, since a criterion for selecting the type of sky starting from the irradiance values has not found until now. The authors propose a new simple method of applying the CIE model, based on the use of the sky index Si. A comparison between calculated luminance data and data measured in Arcavacata of Rende (Italy), Lyon (France) and Pamplona (Spain) show a good performance of this method in comparison with other methods of calculation of luminance existing in the literature.

  1. Identification of Different Classes of Luminal Progenitor Cells within Prostate Tumors

    Directory of Open Access Journals (Sweden)

    Supreet Agarwal

    2015-12-01

    Full Text Available Primary prostate cancer almost always has a luminal phenotype. However, little is known about the stem/progenitor properties of transformed cells within tumors. Using the aggressive Pten/Tp53-null mouse model of prostate cancer, we show that two classes of luminal progenitors exist within a tumor. Not only did tumors contain previously described multipotent progenitors, but also a major population of committed luminal progenitors. Luminal cells, sorted directly from tumors or grown as organoids, initiated tumors of adenocarcinoma or multilineage histological phenotypes, which is consistent with luminal and multipotent differentiation potentials, respectively. Moreover, using organoids we show that the ability of luminal-committed progenitors to self-renew is a tumor-specific property, absent in benign luminal cells. Finally, a significant fraction of luminal progenitors survived in vivo castration. In all, these data reveal two luminal tumor populations with different stem/progenitor cell capacities, providing insight into prostate cancer cells that initiate tumors and can influence treatment response.

  2. The EXIST optical and infra-red telescope (IRT) and imager-spectrometer

    Science.gov (United States)

    Kutyrev, A. S.; Moseley, S. H.; Golisano, C.; Gong, Q.; Allen, B. T.; Gehrels, N.; Grindlay, J. E.; Hong, J. S.; Woodgate, B. E.

    2009-08-01

    The EXIST (Energetic X-ray Imaging Survey Telescope) mission includes the 1.1 m optical Infra-Red Telescope (IRT) which provides the capability to locate, identify, and obtain spectra of transient events, in particular GRB afterglows at redshifts up to epoch of reionization. The instrument includes a high spatial resolution imager, low spectral resolution spectrometer (R~ 30) and high resolution slit spectrometer (R~ 3000). This instrument, with the observatory's rapid reaction response will quickly identify the GRB afterglow, measure its brightness curves, redshift, measure spectral characteristics of the afterglows and measure absorption spectra of the intervening intergalactic medium. With this instrument, high redshift GRBs become important tools for studying the growth of structure, observing the processes through which the universe is reionized.

  3. A method for evaluating luminance non-uniformity of displays by use of a commercially available digital camera.

    Science.gov (United States)

    Kawamoto, Keishin; Tokurei, Shogo; Morishita, Junji

    2017-12-01

    The luminance uniformity of liquid-crystal displays (LCDs) deteriorates with their prolonged use. In this paper, we present a method for evaluating the degree of luminance non-uniformity of LCDs with the use of a commercially available digital camera. In this study, seven monochrome LCDs, which were used during various operating times ranging from 5000 to 25,000 h, were evaluated with use of a camera. The maximum luminance deviation (MLD) was measured on the two-dimensional (2D) images obtained with the camera. In addition, an index of the luminance non-uniformity was calculated as the ratio of the area exhibiting luminance non-uniformity to the area of the entire LCD screen. We determined the area with the luminance non-uniformity by setting the allowable luminance deviation as the judgment criterion to evaluate the degree of luminance non-uniformity. The MLD values were less than 20% for all conditions, and they varied depending on the locations of the luminance measurement. The area ratios of the luminance non-uniformity based on 2D luminance distributions tended to increase with the duration of use of LCDs, and they indicated the degree of luminance non-uniformity of the LCDs regardless of the measurement locations. Our approach of using a commercially available digital camera showed its potential usefulness for providing more detailed and consistent evaluations of the degree of luminance non-uniformity of LCDs based on the 2D luminance distributions.

  4. Infrared Astronomy and Education: Linking Infrared Whole Sky Mapping with Teacher and Student Research

    Science.gov (United States)

    Borders, Kareen; Mendez, Bryan; Thaller, Michelle; Gorjian, Varoujan; Borders, Kyla; Pitman, Peter; Pereira, Vincent; Sepulveda, Babs; Stark, Ron; Knisely, Cindy; Dandrea, Amy; Winglee, Robert; Plecki, Marge; Goebel, Jeri; Condit, Matt; Kelly, Susan

    The Spitzer Space Telescope and the recently launched WISE (Wide Field Infrared Survey Explorer) observe the sky in infrared light. Among the objects WISE will study are asteroids, the coolest and dimmest stars, and the most luminous galaxies. Secondary students can do authentic research using infrared data. For example, students will use WISE data to mea-sure physical properties of asteroids. In order to prepare students and teachers at this level with a high level of rigor and scientific understanding, the WISE and the Spitzer Space Tele-scope Education programs provided an immersive teacher professional development workshop in infrared astronomy.The lessons learned from the Spitzer and WISE teacher and student pro-grams can be applied to other programs engaging them in authentic research experiences using data from space-borne observatories such as Herschel and Planck. Recently, WISE Educator Ambassadors and NASA Explorer School teachers developed and led an infrared astronomy workshop at Arecibo Observatory in PuertoRico. As many common misconceptions involve scale and distance, teachers worked with Moon/Earth scale, solar system scale, and distance and age of objects in the Universe. Teachers built and used basic telescopes, learned about the history of telescopes, explored ground and satellite based telescopes, and explored and worked on models of WISE Telescope. An in-depth explanation of WISE and the Spitzer telescopes gave participants background knowledge for infrared astronomy observations. We taught the electromagnetic spectrum through interactive stations. We will outline specific steps for sec-ondary astronomy professional development, detail student involvement in infrared telescope data analysis, provide data demonstrating the impact of the above professional development on educator understanding and classroom use, and detail future plans for additional secondary professional development and student involvement in infrared astronomy. Funding was

  5. First results from Project SUNBIRD: Supernovae UNmasked By Infra-Red Detection

    Science.gov (United States)

    Kool, Erik C.; Ryder, Stuart D.; Kankare, Erkki; Mattila, Seppo

    2017-11-01

    A substantial number of core-collapse supernovae (CCSNe) are expected to be hosted by starbursting luminous infrared galaxies (LIRGs). However, so far very few CCSNe have been discovered in LIRGs, most likely as a result of dust extinction and lack of contrast in their typically luminous and complex nuclear regions. We present the first results of Project SUNBIRD (Supernovae UNmasked By InfraRed Detection), where we aim to uncover dust-obscured nuclear supernovae by monitoring over 30 LIRGs, using near-infrared state-of-the-art Laser Guide Star Adaptive Optics (LGSAO) imaging on the Gemini South and Keck telescopes. Such discoveries are vital for determining the fraction of supernovae which will be missed as a result of dust obscuration by current and future optical surveys.

  6. Quark Nova Signatures in Super-luminous Supernovae

    Science.gov (United States)

    Kostka, M.; Koning, N.; Leahy, D.; Ouyed, R.; Steffen, W.

    2014-10-01

    Recent observational surveys have uncovered the existence of super-luminous supernovae (SLSNe). In this work we study the light curves of eight SLSNe in the context of dual-shock quark novae. We find that progenitor stars in the range of 25 - 35 M⊙ provide ample energy to power each light curve. An examination into the effects of varying the physical properties of a dual-shock quark nova on light curve composition is undertaken. We conclude that the wide variety of SLSN light curve morphologies can be explained predominantly by variations in the length of time between supernova and quark nova. Our analysis shows that a singular H alpha spectral profile found in three SLSNe can be naturally described in the dual-shock quark nova scenario. Predictions of spectral signatures unique to the dual-shock quark nova are presented.

  7. Probiotics in luminal gastroenterology: the current state of play.

    Science.gov (United States)

    Andrews, J M; Tan, M

    2012-12-01

    In recent years, there has been a growing interest in the use of probiotics in various areas of gastrointestinal (GI) health. Probiotics are defined as live microorganisms that provide beneficial health effects on the host when administered in adequate amounts. Various probiotics have been shown to suppress bacterial growth, modulate the immune system and improve intestinal barrier function. However, despite several studies with promising results, most trials are small and many have substantial methodological limitations. However, with better targeting and appropriate randomised controlled trials, this area may soon yield important therapeutic strategies to optimise GI health. Here, we review the current knowledge of probiotics of relevance to luminal GI health. © 2012 The Authors; Internal Medicine Journal © 2012 Royal Australasian College of Physicians.

  8. Role of epigenetic modifications in luminal breast cancer.

    Science.gov (United States)

    Abdel-Hafiz, Hany A; Horwitz, Kathryn B

    2015-08-01

    Luminal breast cancers represent approximately 75% of cases. Explanations into the causes of endocrine resistance are complex and are generally ascribed to genomic mechanisms. Recently, attention has been drawn to the role of epigenetic modifications in hormone resistance. We review these here. Epigenetic modifications are reversible, heritable and include changes in DNA methylation patterns, modification of histones and altered microRNA expression levels that target the receptors or their signaling pathways. Large-scale analyses indicate distinct epigenomic profiles that distinguish breast cancers from normal and benign tissues. Taking advantage of the reversibility of epigenetic modifications, drugs that target epigenetic modifiers, given in combination with chemotherapies or endocrine therapies, may represent promising approaches to restoration of therapy responsiveness in these cases.

  9. Role of epigenetic modifications in luminal breast cancer

    Science.gov (United States)

    Abdel-Hafiz, Hany A; Horwitz, Kathryn B

    2015-01-01

    Luminal breast cancers represent approximately 75% of cases. Explanations into the causes of endocrine resistance are complex and are generally ascribed to genomic mechanisms. Recently, attention has been drawn to the role of epigenetic modifications in hormone resistance. We review these here. Epigenetic modifications are reversible, heritable and include changes in DNA methylation patterns, modification of histones and altered microRNA expression levels that target the receptors or their signaling pathways. Large-scale analyses indicate distinct epigenomic profiles that distinguish breast cancers from normal and benign tissues. Taking advantage of the reversibility of epigenetic modifications, drugs that target epigenetic modifiers, given in combination with chemotherapies or endocrine therapies, may represent promising approaches to restoration of therapy responsiveness in these cases. PMID:25689414

  10. Luminous Red Galaxies at Z=0.4-0.5

    Science.gov (United States)

    Heap, Sally; Lindler, Don

    2009-01-01

    We report on a study of approx.20,000 luminous red galaxies (LRG's) at z=0.4-0.5 observed by the Sloan Digital Sky Survey. In order to differentiate among them, we measured restframe magnitudes, u (3000-3500 A), b (4200-4800 A), and y (5700-6300 A) from the spectra themselves. The galaxies show a significant range in restframe colors and absolute magnitudes. We binned the spectra according to the restframe u-b color and y-band absolute magnitude in order to increase the S/N. We used 3 approaches to estimate the ages and metal content of these binned spectra: via their spectral energy distributions, from spectral-line indices, and by full spectral fitting. The three methods usually produce discordant results

  11. Differentiating cerebral lymphomas and GBMs featuring luminance distribution analysis

    Science.gov (United States)

    Yamasaki, Toshihiko; Chen, Tsuhan; Hirai, Toshinori; Murakami, Ryuji

    2013-02-01

    Differentiating lymphomas and glioblastoma multiformes (GBMs) is important for proper treatment planning. A number of works have been proposed but there are still some problems. For example, many works depend on thresholding a single feature value, which is susceptible to noise. Non-typical cases that do not get along with such simple thresholding can be found easily. In other cases, experienced observers are required to extract the feature values or to provide some interactions to the system, which is costly. Even if experts are involved, inter-observer variance becomes another problem. In addition, most of the works use only one or a few slice(s) because 3D tumor segmentation is difficult and time-consuming. In this paper, we propose a tumor classification system that analyzes the luminance distribution of the whole tumor region. The 3D MRIs are segmented within a few tens of seconds by using our fast 3D segmentation algorithm. Then, the luminance histogram of the whole tumor region is generated. The typical cases are classified by the histogram range thresholding and the apparent diffusion coefficients (ADC) thresholding. The non-typical cases are learned and classified by a support vector machine (SVM). Most of the processing elements are semi-automatic except for the ADC value extraction. Therefore, even novice users can use the system easily and get almost the same results as experts. The experiments were conducted using 40 MRI datasets (20 lymphomas and 20 GBMs) with non-typical cases. The classification accuracy of the proposed method was 91.1% without the ADC thresholding and 95.4% with the ADC thresholding. On the other hand, the baseline method, the conventional ADC thresholding, yielded only 67.5% accuracy.

  12. 78 FR 25486 - Luminant Generation Company, LLC., Combined License Application for Comanche Peak Nuclear Power...

    Science.gov (United States)

    2013-05-01

    ... COMMISSION Luminant Generation Company, LLC., Combined License Application for Comanche Peak Nuclear Power... Generation Company, LLC. (Luminant) for the proposed facility to be located in Somervell County, Texas. In.... No changes are being made in the types of effluents that may be released offsite. There is no...

  13. Consecutive daily measurements of luminal concentrations of lactate in the rectum in septic shock patients

    DEFF Research Database (Denmark)

    Ibsen, Michael; Wiis, Jørgen; Waldau, Tina

    2012-01-01

    In a recent study we found no difference in the concentrations of luminal lactate in the rectum between nonsurvivors and survivors in early septic shock (......In a recent study we found no difference in the concentrations of luminal lactate in the rectum between nonsurvivors and survivors in early septic shock (...

  14. Facile and Low-Temperature Fabrication of Thermochromic Cr2O3/VO2 Smart Coatings: Enhanced Solar Modulation Ability, High Luminous Transmittance and UV-Shielding Function.

    Science.gov (United States)

    Chang, Tianci; Cao, Xun; Li, Ning; Long, Shiwei; Gao, Xiang; Dedon, Liv R; Sun, Guangyao; Luo, Hongjie; Jin, Ping

    2017-08-09

    In the pursuit of energy efficient materials, vanadium dioxide (VO2) based smart coatings have gained much attention in recent years. For smart window applications, VO2 thin films should be fabricated at low temperature to reduce the cost in commercial fabrication and solve compatibility problems. Meanwhile, thermochromic performance with high luminous transmittance and solar modulation ability, as well as effective UV shielding function has become the most important developing strategy for ideal smart windows. In this work, facile Cr2O3/VO2 bilayer coatings on quartz glasses were designed and fabricated by magnetron sputtering at low temperatures ranging from 250 to 350 °C as compared with typical high growth temperatures (>450 °C). The bottom Cr2O3 layer not only provides a structural template for the growth of VO2 (R), but also serves as an antireflection layer for improving the luminous transmittance. It was found that the deposition of Cr2O3 layer resulted in a dramatic enhancement of the solar modulation ability (56.4%) and improvement of luminous transmittance (26.4%) when compared to single-layer VO2 coating. According to optical measurements, the Cr2O3/VO2 bilayer structure exhibits excellent optical performances with an enhanced solar modulation ability (ΔTsol = 12.2%) and a high luminous transmittance (Tlum,lt = 46.0%), which makes a good balance between ΔTsol and Tlum for smart windows applications. As for UV-shielding properties, more than 95.8% UV radiation (250-400 nm) can be blocked out by the Cr2O3/VO2 structure. In addition, the visualized energy-efficient effect was modeled by heating a beaker of water using infrared imaging method with/without a Cr2O3/VO2 coating glass.

  15. Revealing the ISM in high redshift starburst galaxies: An analysis of Herschel PACS and SPIRE FTS spectroscopic observations of HerMES and H-ATLAS-selected lensed galaxies

    Science.gov (United States)

    Cooray, Asantha

    In the quest to develop a fundamental understanding of galaxy formation and evolution, observations of dusty star-forming galaxies (DSFGs) promise significant progress this decade. The importance of DSFGs is highlighted by the fact that half of the energy emitted by extragalactic sources emerges as dust-reprocessed light at infrared (IR) to sub millimeter wavelength. In the post-herschel\\ era, we are now at a unique position to tackle some of the key questions on galaxy formation and evolution because of the large area Herschel's Key Project surveys (HerMES and H-ATLAS). In particular those surveys have allowed us to identify a sample of 250 strongly gravitationally lensed DSFGs at z > 1. They give us a unique opportunity to dissect the detailed structures and kinematics of DSFGs. The Herschel Science Archive also contains individual follow up data on 44 and 25 of the brightest sources with SPIRE-FTS and PACS, respectively, in the spectroscopy mode, taking over 250 hours in four open-time programs. Only one of the 44 SPIRE FTS targets has yet to appear in the published literature. One of the four include an open-time 2 PACS spectroscopy program that was led at UCI by a former postdoc from the PI's group. That program was initially approved at Priority 2 in 2011, but was triggered in late 2012 and achieved 100% completion during the last two weeks of Herschel lifetime in May 2013. This archival analysis, interpretation, and modeling program involves two parts: (i) PACS spectroscopy in 50 to 200 microns of 25 lensed galaxies in the fine-structure emission lines [SiII]34, [SIII]33, [OIV]26, [OIII]52, [NIII]57 and [OI]63, and the molecular hydrogen H_2 S(0) and S(1). (ii) SPIRE FTS spectroscopy of 44 lensed galaxies, including above 25, over the wavelength range of 200 to 600 microns targeting [CII]158, [OIII]88, [OI]63/145, and [NI]122. The analysis will lead to a better understanding of the ISM of starbursting galaxies that span 1 z generation astrophysicists in the

  16. Predicting future space near-IR grism surveys using the WFC3 infrared spectroscopic parallels survey

    Energy Technology Data Exchange (ETDEWEB)

    Colbert, James W.; Atek, Hakim [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Teplitz, Harry; Rafelski, Marc [Infrared Processing and Analysis Center, Caltech, Pasadena, CA 91125 (United States); Bunker, Andrew [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Ross, Nathaniel; Malkan, Matt [Department of Physics and Astronomy, University of California, Los Angeles, CA (United States); Scarlata, Claudia; Bedregal, Alejandro G. [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Dominguez, Alberto; Masters, Dan; Siana, Brian [Department of Physics and Astronomy, University of California Riverside, Riverside, CA 92521 (United States); Dressler, Alan; McCarthy, Patrick [Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States); Henry, Alaina [Astrophysics Science Division, Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States); Martin, Crystal L. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

    2013-12-10

    We present near-infrared emission line counts and luminosity functions from the Hubble Space Telescope Wide Field Camera 3 Infrared Spectroscopic Parallels (WISP) program for 29 fields (0.037 deg{sup 2}) observed using both the G102 and G141 grism. Altogether we identify 1048 emission line galaxies with observed equivalent widths greater than 40 Å, 467 of which have multiple detected emission lines. We use simulations to correct for significant (>20%) incompleteness introduced in part by the non-dithered, non-rotated nature of the grism parallels. The WISP survey is sensitive to fainter flux levels ((3-5) × 10{sup –17} erg s{sup –1} cm{sup –2}) than the future space near-infrared grism missions aimed at baryonic acoustic oscillation cosmology ((1-4) × 10{sup –16} erg s{sup –1} cm{sup –2}), allowing us to probe the fainter emission line galaxies that the shallower future surveys may miss. Cumulative number counts of 0.7 < z < 1.5 galaxies reach 10,000 deg{sup –2} above an Hα flux of 2 × 10{sup –16} erg s{sup –1} cm{sup –2}. Hα-emitting galaxies with comparable [O III] flux are roughly five times less common than galaxies with just Hα emission at those flux levels. Galaxies with low Hα/[O III] ratios are very rare at the brighter fluxes that future near-infrared grism surveys will probe; our survey finds no galaxies with Hα/[O III] < 0.95 that have Hα flux greater than 3 × 10{sup –16} erg s{sup –1} cm{sup –2}. Our Hα luminosity function contains a comparable number density of faint line emitters to that found by the Near IR Camera and Multi-Object Spectrometer near-infrared grism surveys, but significantly fewer (factors of 3-4 less) high-luminosity emitters. We also find that our high-redshift (z = 0.9-1.5) counts are in agreement with the high-redshift (z = 1.47) narrowband Hα survey of HiZELS (Sobral et al.), while our lower redshift luminosity function (z = 0.3-0.9) falls slightly below their z = 0.84 result. The evolution

  17. Breast cancer in Iraq is associated with a unimodally distributed predominance of luminal type B over luminal type A surrogates from young to old age.

    Science.gov (United States)

    Majid, Runnak A; Hassan, Hemin A; Muhealdeen, Dana N; Mohammed, Hazha A; Hughson, Michael D

    2017-04-07

    Breast cancer has recently increased in post-menopausal Iraqi women. In Western countries at high-risk for breast cancer, there is a bimodal increase in estrogen receptor (ER) positive tumors with a peak of low proliferation rate luminal A over higher proliferation rate luminal B tumors after 60 years of age. The aim of this study was to analyze in Iraqi women whether shifts are occurring in immunohistochemical (IHC) surrogates of molecular breast cancer subtypes toward a high-risk profile. Age specific and age standardized womens breast cancer incidence was estimated for the years 2006 through 2012. IHC results of ER, PR, HER2, and Ki67 testing were analyzed on the breast cancers of 125 Arabic and 725 Kurdish women by frequency of distribution and by age. Between 2006 and 2012, age standardized incidence of breast cancer in Iraq increased from 30 to 40/100,000 women with the increase specifically occurring in women ≥ 60 years old (P Breast cancers in Kurdish women ≥ 60 years old may also have increased (P = 0.047) with urban exceeding rural rates by 2:1. For both Kurdish and Arabic women, there was a marked predominance of luminal B tumors at all ages in which luminal B and luminal A tumors were asymmetric skewed toward older age but with no late luminal A age peak. Older Iraqi women do not show the bimodal shift toward higher rates of luminal A breast cancers seen in the West. The modest increase in age standardized incidence of breast cancer in Iraqi is being seen specifically in older women and may be better attributed to a trend for care in urban cancer centers rather than changing tumor characteristics.

  18. Research on effects of baffle position in an integrating sphere on the luminous flux measurement

    Science.gov (United States)

    Lin, Fangsheng; Li, Tiecheng; Yin, Dejin; Lai, Lei; Xia, Ming

    2016-09-01

    In the field of optical metrology, luminous flux is an important index to characterize the quality of electric light source. Currently, the majority of luminous flux measurement is based on the integrating sphere method, so measurement accuracy of integrating sphere is the key factor. There are plenty of factors affecting the measurement accuracy, such as coating, power and the position of light source. However, the baffle which is a key part of integrating sphere has important effects on the measurement results. The paper analyzes in detail the principle of an ideal integrating sphere. We use moving rail to change the relative position of baffle and light source inside the sphere. By experiments, measured luminous flux values at different distances between the light source and baffle are obtained, which we used to take analysis of the effects of different baffle position on the measurement. By theoretical calculation, computer simulation and experiment, we obtain the optimum position of baffle for luminous flux measurements. Based on the whole luminous flux measurement error analysis, we develop the methods and apparatus to improve the luminous flux measurement accuracy and reliability. It makes our unifying and transferring work of the luminous flux more accurate in East China and provides effective protection for our traceability system.

  19. Luminance uniformity study of OLED lighting panels depending on OLED device structures.

    Science.gov (United States)

    Bae, Hyeong Woo; Son, Young Hoon; Kang, Byoung Yeop; Lee, Jung Min; Nam, Hyoungsik; Kwon, Jang Hyuk

    2015-11-30

    This paper describes the luminance uniformity of OLED lighting panels depending on OLED device structures of single emission layer (single-EML), 2-tandem, and 3-tandem. The luminance distribution is evaluated through the circuit simulation and the fabricated panel measurement. In the simulation results with yellow-green color panels of 30 × 80 mm2 emission area, a 3-tandem structure shows the lowest non-uniformity (1.34% at 7.5V), compared to single-EML (5.67% at 2.8V) and 2-tandem (2.78% at 5.3 V) structures at 1,000 cd/m2. The luminance non-uniformity is germane to the OLED conductance showing that the high luminance-current efficiency is of the most importance to achieve the uniform voltage and luminance distribution. In measurement, a 3-tandem structure also achieves the most uniform luminance distribution with non-uniformity of 4.1% while single EML and 2-tandem structures accomplish 9.6%, and 6.4%, respectively, at ~1,000 cd/m2. In addition, the simulation results ensure that a 3-tandem structure panel is allowed to be enlarged the panel size up to about 5,000 mm2 for lower luminance non-uniformity than 10% without any auxiliary metal electrodes.

  20. Tritium application: self-luminous glass tube(SLGT)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.; Lee, S.K.; Chung, E.S.; Kim, K.S.; Kim, W.S. [Nuclear Power Lab., Korea Electric Power Research Inst. (KEPRI), Daejeon (Korea); Nam, G.J. [Engineering Information Technology Center, Inst. for Advanced Engineering (IAE), Kyonggi-do (Korea)

    2005-07-01

    To manufacture SLGTs (self-luminous glass tubes), 4 core technologies are needed: coating technology, tritium injection technology, laser sealing/cutting technology and tritium handling technology. The inside of the glass tubes is coated with greenish ZnS phosphor particles with sizes varying from 4{proportional_to}5 [{mu}m], and Cu, and Al as an activator and a co-dopant, respectively. We also found that it would be possible to produce a phosphor coated glass tube for the SLGT using the well established cold cathode fluorescent lamp (CCFL) bulb manufacturing technology. The conceptual design of the main process loop (PL) is almost done. A delicate technique will be needed for the sealing/cutting of the glass tubes. Instead of the existing torch technology, a new technology using a pulse-type laser is under investigation. The design basis of the tritium handling facilities is to minimize the operator's exposure to tritium uptake and the emission of tritium to the environment. To fulfill the requirements, major tritium handling components are located in the secondary containment such as the glove boxes (GBs) and/or the fume hoods. The tritium recovery system (TRS) is connected to a GB and PL to minimize the release of tritium as well as to remove the moisture and oxygen in the GB. (orig.)

  1. Green Fluorescent Organic Light Emitting Device with High Luminance

    Directory of Open Access Journals (Sweden)

    Ning YANG

    2014-06-01

    Full Text Available In this work, we fabricated the small molecule green fluorescent bottom-emission organic light emitting device (OLED with the configuration of glass substrate/indium tin oxide (ITO/Copper Phthalocyanine (CuPc 25 nm/ N,N’-di(naphthalen-1-yl-N,N’-diphenyl-benzidine (NPB 45 nm/ tris(8-hydroxyquinoline aluminium (Alq3 60 nm/ Lithium fluoride (LiF 1 nm/Aluminum (Al 100 nm where CuPc and NPB are the hole injection layer and the hole transport layer, respectively. CuPc is introduced in this device to improve carrier injection and efficiency. The experimental results indicated that the turn-on voltage is 2.8 V with a maximum luminance of 23510 cd/m2 at 12 V. The maximum current efficiency and power efficiency are 4.8 cd/A at 100 cd/m2 and 4.2 lm/W at 3 V, respectively. The peak of electroluminance (EL spectrum locates at 530 nm which is typical emission peak of green light. In contrast, the maximum current efficiency and power efficiency of the device without CuPc are only 4.0 cd/A at 100 mA/cm2 and 4.2 lm/W at 3.6 V, respectively.

  2. Notch3 marks clonogenic mammary luminal progenitor cells in vivo.

    Science.gov (United States)

    Lafkas, Daniel; Rodilla, Veronica; Huyghe, Mathilde; Mourao, Larissa; Kiaris, Hippokratis; Fre, Silvia

    2013-10-14

    The identity of mammary stem and progenitor cells remains poorly understood, mainly as a result of the lack of robust markers. The Notch signaling pathway has been implicated in mammary gland development as well as in tumorigenesis in this tissue. Elevated expression of the Notch3 receptor has been correlated to the highly aggressive "triple negative" human breast cancer. However, the specific cells expressing this Notch paralogue in the mammary gland remain unknown. Using a conditionally inducible Notch3-CreERT2(SAT) transgenic mouse, we genetically marked Notch3-expressing cells throughout mammary gland development and followed their lineage in vivo. We demonstrate that Notch3 is expressed in a highly clonogenic and transiently quiescent luminal progenitor population that gives rise to a ductal lineage. These cells are capable of surviving multiple successive pregnancies, suggesting a capacity to self-renew. Our results also uncover a role for the Notch3 receptor in restricting the proliferation and consequent clonal expansion of these cells.

  3. Cosmological information in the intrinsic alignments of luminous red galaxies

    Science.gov (United States)

    Chisari, Nora Elisa; Dvorkin, Cora

    2013-12-01

    The intrinsic alignments of galaxies are usually regarded as a contaminant to weak gravitational lensing observables. The alignment of Luminous Red Galaxies, detected unambiguously in observations from the Sloan Digital Sky Survey, can be reproduced by the linear tidal alignment model of Catelan, Kamionkowski & Blandford (2001) on large scales. In this work, we explore the cosmological information encoded in the intrinsic alignments of red galaxies. We make forecasts for the ability of current and future spectroscopic surveys to constrain local primordial non-Gaussianity and Baryon Acoustic Oscillations (BAO) in the cross-correlation function of intrinsic alignments and the galaxy density field. For the Baryon Oscillation Spectroscopic Survey, we find that the BAO signal in the intrinsic alignments is marginally significant with a signal-to-noise ratio of 1.8 and 2.2 with the current LOWZ and CMASS samples of galaxies, respectively, and increasing to 2.3 and 2.7 once the survey is completed. For the Dark Energy Spectroscopic Instrument and for a spectroscopic survey following the EUCLID redshift selection function, we find signal-to-noise ratios of 12 and 15, respectively. Local type primordial non-Gaussianity, parametrized by fNL = 10, is only marginally significant in the intrinsic alignments signal with signal-to-noise ratios < 2 for the three surveys considered.

  4. Atmosphere-based image classification through luminance and hue

    Science.gov (United States)

    Xu, Feng; Zhang, Yujin

    2005-07-01

    In this paper a novel image classification system is proposed. Atmosphere serves an important role in generating the scene"s topic or in conveying the message behind the scene"s story, which belongs to abstract attribute level in semantic levels. At first, five atmosphere semantic categories are defined according to rules of photo and film grammar, followed by global luminance and hue features. Then the hierarchical SVM classifiers are applied. In each classification stage, corresponding features are extracted and the trained linear SVM is implemented, resulting in two classes. After three stages of classification, five atmosphere categories are obtained. At last, the text annotation of the atmosphere semantics and the corresponding features by Extensible Markup Language (XML) in MPEG-7 is defined, which can be integrated into more multimedia applications (such as searching, indexing and accessing of multimedia content). The experiment is performed on Corel images and film frames. The classification results prove the effectiveness of the definition of atmosphere semantic classes and the corresponding features.

  5. Optical luminosity of the transient luminous phenomena in Hessdalen, Norway

    Science.gov (United States)

    Gitle Hauge, Bjørn; Kjøniksen, Anna-Lena; Petter Strand, Erling

    2017-04-01

    Transient luminous phenomena has been observed in the low atmosphere over Hessdalen valley for several decades, first report is claimed to be 200 years old. The area is scattered with old copper, zinc, sulphur and iron mines. The river Hesja divides the valley, running south to north. The river descends from 800 m altitude to 600m. In the middle of the valley, an old copper and sulphur mine feeds the river with its acidic sulphur pollution. Eyewitnesses have reported lights emerging from the river, but most reports are of lights suddenly emerging in low altitudes over the valley, 1000m - 2000m altitude. Common colours are white, yellow, orange and blue. Green is absent. The optical spectrum of the white lights has been obtained several times, indicating a continuous spectrum. The luminosity of the Hessdalen lights has been debated, some speculating that the phenomenońs radiant power reaches up to 1MW. A more moderate calculation done by Teodorani in 2004 suggests 19KW. The cause of the huge difference is due to uncertainty in establishing correct distance to the phenomenon. Recent discoveries done by this team, indicates that the radiant power is usually much lower. For the first time in Hessdalen, pictures with optical spectrums was obtained at a distance not more than 500m. Two similar observations were done from the same position, indicating a possible birthplace. Atmospheric data and spectrum analysis was also coinciding. Data from this short distance observation will be presented.

  6. Epigenetic Mechanisms of Tamoxifen Resistance in Luminal Breast Cancer

    Directory of Open Access Journals (Sweden)

    Hany A. Abdel-Hafiz

    2017-07-01

    Full Text Available Breast cancer is one of the most common cancers and the second leading cause of cancer death in the United States. Estrogen receptor (ER-positive cancer is the most frequent subtype representing more than 70% of breast cancers. These tumors respond to endocrine therapy targeting the ER pathway including selective ER modulators (SERMs, selective ER downregulators (SERDs and aromatase inhibitors (AIs. However, resistance to endocrine therapy associated with disease progression remains a significant therapeutic challenge. The precise mechanisms of endocrine resistance remain unclear. This is partly due to the complexity of the signaling pathways that influence the estrogen-mediated regulation in breast cancer. Mechanisms include ER modifications, alteration of coregulatory function and modification of growth factor signaling pathways. In this review, we provide an overview of epigenetic mechanisms of tamoxifen resistance in ER-positive luminal breast cancer. We highlight the effect of epigenetic changes on some of the key mechanisms involved in tamoxifen resistance, such as tumor-cell heterogeneity, ER signaling pathway and cancer stem cells (CSCs. It became increasingly recognized that CSCs are playing an important role in driving metastasis and tamoxifen resistance. Understanding the mechanism of tamoxifen resistance will provide insight into the design of novel strategies to overcome the resistance and make further improvements in breast cancer therapeutics.

  7. The Weak Lensing Masses of Filaments between Luminous Red Galaxies

    Science.gov (United States)

    Epps, Seth D.; Hudson, Michael J.

    2017-07-01

    In the standard model of non-linear structure formation, a cosmic web of dark-matter-dominated filaments connects dark matter haloes. In this paper, we stack the weak lensing signal of an ensemble of filaments between groups and clusters of galaxies. Specifically, we detect the weak lensing signal, using CFHTLenS galaxy ellipticities, from stacked filaments between Sloan Digital Sky Survey (SDSS)-III/Baryon Oscillation Spectroscopic Survey luminous red galaxies (LRGs). As a control, we compare the physical LRG pairs with projected LRG pairs that are more widely separated in redshift space. We detect the excess filament mass density in the projected pairs at the 5σ level, finding a mass of (1.6 ± 0.3) × 1013 M⊙ for a stacked filament region 7.1 h-1 Mpc long and 2.5 h-1 Mpc wide. This filament signal is compared with a model based on the three-point galaxy-galaxy-convergence correlation function, as developed in Clampitt et al., yielding reasonable agreement.

  8. Confirmation of the Luminous Blue Variable Status of MWC 930

    Directory of Open Access Journals (Sweden)

    A. S. Miroshnichenko

    2014-01-01

    Full Text Available We present spectroscopic and photometric observations of the emission-line star MWC 930 (V446 Sct during its long-term optical brightening in 2006–2013. Based on our earlier data we suggested that the object has features found in Luminous Blue Variables (LBV, such as a high luminosity (~3 105 L⊙, a low wind terminal velocity (~140 km s−1, and a tendency to show strong brightness variations (~1 mag over 20 years. For the last ~7 years it has been exhibiting a continuous optical and near-IR brightening along with a change of the emission-line spectrum appearance and cooling of the star’s photosphere. We present the object’s V-band light curve, analyze the spectral variations, and compare the observed properties with those of other recognized Galactic LBVs, such as AG Car and HR Car. Overall we conclude the MWC 930 is a bona fide Galactic LBV that is currently in the middle of an S Dor cycle.

  9. Intrinsic Spectra of Hyperluminous Infrared Galaxies

    Science.gov (United States)

    Rieke, George; Hines, Dean

    2004-09-01

    We will use the low and high spectral resolution capabilities of the IRS aboard SIRTF to obtain high signal-to-noise mid-infrared spectra of a small sample of the most luminous Active Galactic Nuclei, which are characterized by their "warm" far-infrared spectral energy distributions as obtained by IRAS (the so called Hyperluminous Infrared Galaxies or HIGs). The sample consists of both Type 2 and Type 1 AGNs. The Type 1 objects present a relatively unobscured view of the central engine, and also have a polarized (scattered) component that is completely unobscured. The Type 2 objects have Type 1 polarized spectra, but this scattered light is highly extinguished indicating some obscuration even along the line of sight to the scattering region. The sample will allow us to compare the properties of the Type 1s and Type 2s, thus providing a check on the orientation and providing strong constraints on the geometry and internal structure of all four objects.

  10. Glutamate prevents intestinal atrophy via luminal nutrient sensing in a mouse model of total parenteral nutrition

    DEFF Research Database (Denmark)

    Xiao, Weidong; Feng, Yongjia; Holst, Jens Juul

    2014-01-01

    was regulated by T1R3 and mGluR5, suggesting a novel negative regulator pathway for IEC proliferation not previously described. Loss of luminal nutrients with TPN administration may widely affect intestinal taste sensing. GLM has previously unrecognized actions on IEC growth and EBF. Restoring luminal sensing......Small intestine luminal nutrient sensing may be crucial for modulating physiological functions. However, its mechanism of action is incompletely understood. We used a model of enteral nutrient deprivation, or total parenteral nutrition (TPN), resulting in intestinal mucosal atrophy and decreased...

  11. Evaluation of High Dynamic Range Photography as a Luminance Mapping Technique

    Energy Technology Data Exchange (ETDEWEB)

    Inanici, Mehlika; Galvin, Jim

    2004-12-30

    The potential, limitations, and applicability of the High Dynamic Range (HDR) photography technique is evaluated as a luminance mapping tool. Multiple exposure photographs of static scenes are taken with a Nikon 5400 digital camera to capture the wide luminance variation within the scenes. The camera response function is computationally derived using the Photosphere software, and is used to fuse the multiple photographs into HDR images. The vignetting effect and point spread function of the camera and lens system is determined. Laboratory and field studies have shown that the pixel values in the HDR photographs can correspond to the physical quantity of luminance with reasonable precision and repeatability.

  12. Low-level motion analysis of color and luminance for perception of 2D and 3D motion.

    Science.gov (United States)

    Shioiri, Satoshi; Yoshizawa, Masanori; Ogiya, Mistuharu; Matsumiya, Kazumichi; Yaguchi, Hirohisa

    2012-06-26

    We investigated the low-level motion mechanisms for color and luminance and their integration process using 2D and 3D motion aftereffects (MAEs). The 2D and 3D MAEs obtained in equiluminant color gratings showed that the visual system has the low-level motion mechanism for color motion as well as for luminance motion. The 3D MAE is an MAE for motion in depth after monocular motion adaptation. Apparent 3D motion can be perceived after prolonged exposure of one eye to lateral motion because the difference in motion signal between the adapted and unadapted eyes generates interocular velocity differences (IOVDs). Since IOVDs cannot be analyzed by the high-level motion mechanism of feature tracking, we conclude that a low-level motion mechanism is responsible for the 3D MAE. Since we found different temporal frequency characteristics between the color and luminance stimuli, MAEs in the equiluminant color stimuli cannot be attributed to a residual luminance component in the color stimulus. Although a similar MAE was found with a luminance and a color test both for 2D and 3D motion judgments after adapting to either color or luminance motion, temporal frequency characteristics were different between the color and luminance adaptation. The visual system must have a low-level motion mechanism for color signals as for luminance ones. We also found that color and luminance motion signals are integrated monocularly before IOVD analysis, showing a cross adaptation effect between color and luminance stimuli. This was supported by an experiment with dichoptic presentations of color and luminance tests. In the experiment, color and luminance tests were presented in the different eyes dichoptically with four different combinations of test and adaptation: color or luminance test in the adapted eye after color or luminance adaptation. Findings of little or no influence of the adaptation/test combinations indicate the integration of color and luminance motion signals prior to the

  13. The first VLBI image of an infrared-faint radio source

    Science.gov (United States)

    Middelberg, E.; Norris, R. P.; Tingay, S.; Mao, M. Y.; Phillips, C. J.; Hotan, A. W.

    2008-11-01

    Context: We investigate the joint evolution of active galactic nuclei and star formation in the Universe. Aims: In the 1.4 GHz survey with the Australia Telescope Compact Array of the Chandra Deep Field South and the European Large Area ISO Survey - S1 we have identified a class of objects which are strong in the radio but have no detectable infrared and optical counterparts. This class has been called Infrared-Faint Radio Sources, or IFRS. 53 sources out of 2002 have been classified as IFRS. It is not known what these objects are. Methods: To address the many possible explanations as to what the nature of these objects is we have observed four sources with the Australian Long Baseline Array. Results: We have detected and imaged one of the four sources observed. Assuming that the source is at a high redshift, we find its properties in agreement with properties of Compact Steep Spectrum sources. However, due to the lack of optical and infrared data the constraints are not particularly strong.

  14. Far-infrared spectroscopy of a lensed starburst: a blind redshift from Herschel

    Science.gov (United States)

    George, R. D.; Ivison, R. J.; Hopwood, R.; Riechers, D. A.; Bussmann, R. S.; Cox, P.; Dye, S.; Krips, M.; Negrello, M.; Neri, R.; Serjeant, S.; Valtchanov, I.; Baes, M.; Bourne, N.; Clements, D. L.; De Zotti, G.; Dunne, L.; Eales, S. A.; Ibar, E.; Maddox, S.; Smith, M. W. L.; Valiante, E.; van der Werf, P.

    2013-11-01

    We report the redshift of HATLAS J132427.0+284452 (hereafter HATLAS J132427), a gravitationally lensed starburst galaxy, the first determined `blind' by the Herschel Space Observatory. This is achieved via the detection of [C II] consistent with z = 1.68 in a far-infrared spectrum taken with the SPIRE Fourier Transform Spectrometer (FTS). We demonstrate that the [C II] redshift is secure via detections of CO J = 2 → 1 and 3 → 2 using the Combined Array for Research in Millimeter-wave Astronomy and the Institut de Radioastronomie Millimétrique's Plateau de Bure Interferometer. The intrinsic properties appear typical of high-redshift starbursts despite the high lensing-amplified fluxes, proving the ability of the FTS to probe this population with the aid of lensing. The blind detection of [C II] demonstrates the potential of the SPICA Far-infrared Instrument imaging spectrometer, proposed for the much more sensitive Space Infrared Telescope for Cosmology and Astrophysics mission, to determine redshifts of multiple dusty galaxies simultaneously without the benefit of lensing.

  15. The Space Infrared Interferometric Telescope (SPIRIT): The Mission Design Solution Space and the Art of the Possible

    Science.gov (United States)

    Leisawitz, David; Hyde, T. Tupper; Rinehart, Stephen A.; Weiss, Michael

    2008-01-01

    Although the Space Infrared Interferometric Telescope (SPIRIT) was studied as a candidate NASA Origins Probe mission, the real world presents a broader set of options, pressures, and constraints. Fundamentally, SPIRIT is a far-IR observatory for high-resolution imaging and spectroscopy designed to address a variety of compelling scientific questions. How do planetary systems form from protostellar disks, dousing some planets in water while leaving others dry? Where do planets form, and why are some ice giants while others are rocky? How did high-redshift galaxies form and merge to form the present-day population of galaxies? This paper takes a pragmatic look at the mission design solution space for SPIRIT, presents Probe-class and facility-class mission scenarios, and describes optional design changes. The costs and benefits of various mission design alternatives are roughly evaluated, giving a basis for further study and to serve as guidance to policy makers.

  16. A synaptic mechanism for retinal adaptation to luminance and contrast.

    Science.gov (United States)

    Jarsky, Tim; Cembrowski, Mark; Logan, Stephen M; Kath, William L; Riecke, Hermann; Demb, Jonathan B; Singer, Joshua H

    2011-07-27

    The gain of signaling in primary sensory circuits is matched to the stimulus intensity by the process of adaptation. Retinal neural circuits adapt to visual scene statistics, including the mean (background adaptation) and the temporal variance (contrast adaptation) of the light stimulus. The intrinsic properties of retinal bipolar cells and synapses contribute to background and contrast adaptation, but it is unclear whether both forms of adaptation depend on the same cellular mechanisms. Studies of bipolar cell synapses identified synaptic mechanisms of gain control, but the relevance of these mechanisms to visual processing is uncertain because of the historical focus on fast, phasic transmission rather than the tonic transmission evoked by ambient light. Here, we studied use-dependent regulation of bipolar cell synaptic transmission evoked by small, ongoing modulations of membrane potential (V(M)) in the physiological range. We made paired whole-cell recordings from rod bipolar (RB) and AII amacrine cells in a mouse retinal slice preparation. Quasi-white noise voltage commands modulated RB V(M) and evoked EPSCs in the AII. We mimicked changes in background luminance or contrast, respectively, by depolarizing the V(M) or increasing its variance. A linear systems analysis of synaptic transmission showed that increasing either the mean or the variance of the presynaptic V(M) reduced gain. Further electrophysiological and computational analyses demonstrated that adaptation to mean potential resulted from both Ca channel inactivation and vesicle depletion, whereas adaptation to variance resulted from vesicle depletion alone. Thus, background and contrast adaptation apparently depend in part on a common synaptic mechanism.

  17. Extracellular Vesicles in Luminal Fluid of the Ovine Uterus

    Science.gov (United States)

    Burns, Gregory; Brooks, Kelsey; Wildung, Mark; Navakanitworakul, Raphatphorn; Christenson, Lane K.; Spencer, Thomas E.

    2014-01-01

    Microvesicles and exosomes are nanoparticles released from cells and can contain small RNAs, mRNA and proteins that affect cells at distant sites. In sheep, endogenous beta retroviruses (enJSRVs) are expressed in the endometrial epithelia of the uterus and can be transferred to the conceptus trophectoderm. One potential mechanism of enJSRVs transfer from the uterus to the conceptus is via exosomes/microvesicles. Therefore, studies were conducted to evaluate exosomes in the uterine luminal fluid (ULF) of sheep. Exosomes/microvesicles (hereafter referred to as extracellular vesicles) were isolated from the ULF of day 14 cyclic and pregnant ewes using ExoQuick-TC. Transmission electron microscopy and nanoparticle tracking analysis found the isolates contained vesicles that ranged from 50 to 200 nm in diameter. The isolated extracellular vesicles were positive for two common markers of exosomes (CD63 and HSP70) by Western blot analysis. Proteins in the extracellular vesicles were determined by mass spectrometry and Western blot analysis. Extracellular vesicle RNA was analyzed for small RNAs by sequencing and enJSRVs RNA by RT-PCR. The ULF extracellular vesicles contained a large number of small RNAs and miRNAs including 81 conserved mature miRNAs. Cyclic and pregnant ULF extracellular vesicles contained enJSRVs env and gag RNAs that could be delivered to heterologous cells in vitro. These studies support the hypothesis that ULF extracellular vesicles can deliver enJSRVs RNA to the conceptus, which is important as enJSRVs regulate conceptus trophectoderm development. Importantly, these studies support the idea that extracellular vesicles containing select miRNAs, RNAs and proteins are present in the ULF and likely have a biological role in conceptus-endometrial interactions important for the establishment and maintenance of pregnancy. PMID:24614226

  18. Hubble space telescope spectroscopy of four luminous compact blue galaxies at intermediate redshift

    OpenAIRE

    Hoyos, C.; Guzmán, R.; Bershady, M. A.; D. C. Koo; Díaz, Angeles I.

    2004-01-01

    This is an electronic version of an article published in The Astronomical Journal. Hoyos, C. et al. Hubble space telescope spectroscopy of four luminous compact blue galaxies at intermediate redshift. The Astronomical Journal 128 (2004): 1541-1551

  19. Distribution and species composition of planktonic luminous bacteria in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaiah, N.; Chandramohan, D.

    Distribution of the total viable heterotrophic bacteria and the luminous bacteria in the neretic and oceanic waters of the west coast of India was studied. Counts of viable heterotrophs fluctuated widely, generally with a decrease in their number...

  20. Intravascular photoacoustic imaging of exogenously labeled atherosclerotic plaque through luminal blood

    Science.gov (United States)

    Yeager, Doug; Karpiouk, Andrei; Wang, Bo; Amirian, James; Sokolov, Konstantin; Smalling, Richard; Emelianov, Stanislav

    2012-10-01

    Combined intravascular ultrasound and intravascular photoacoustic (IVUS/IVPA) imaging has been previously established as a viable means for assessing atherosclerotic plaque morphological and compositional characteristics using both endogenous and exogenous contrast. In this study, IVUS/IVPA imaging of atherosclerotic rabbit aortas following systemic injection of gold nanorods (AUNRs) with peak absorbance within the tissue optical window is performed. Ex vivo imaging results reveal a high photoacoustic signal from localized AUNRs in regions with atherosclerotic plaques. Corresponding histological staining further confirms the preferential extravasation of AUNRs in atherosclerotic regions with compromised luminal endothelium and acute inflammation. The ability to detect AUNRs using combined IVUS and photoacoustic imaging in the presence of luminal saline and luminal blood is evaluated using both spectroscopic and single wavelength IVPA imaging techniques. Results demonstrate that AUNR detection within the arterial wall can be achieved using both methods, even in the case of imaging through luminal blood.

  1. Luminal fluid of epididymis and vas deferens contributes to sperm chromatin fragmentation.

    Science.gov (United States)

    Gawecka, Joanna E; Boaz, Segal; Kasperson, Kay; Nguyen, Hieu; Evenson, Donald P; Ward, W Steven

    2015-12-01

    Do the luminal fluids of the epididymis and the vas deferens contribute to sperm chromatin fragmentation (SCF) in mice? The luminal fluids of both organs are required for activating SCF in mice, but the vas deferens luminal fluid does this more efficiently than that of the epididymis. Mice sperm have the ability to degrade their DNA in an apoptotic-like fashion when treated with divalent cations in a process termed SCF. SCF has two steps: the induction of reversible double-strand DNA breaks at the nuclear matrix attachment sites, followed by the irreversible degradation of DNA by nuclease. Single stranded DNA breaks accompany SCF. Luminal fluids from two reproductive organs of the mouse (B6D2F1 strain), the epididymis and vas deferens, were extracted and tested for SCF activation with divalent cations using four different combinations of the sperm and the surrounding luminal fluids: (i) in situ--sperm were kept in their luminal fluid and activated directly; (ii) reconstituted--sperm were centrifuged and resuspended in their luminal fluid before SCF activation; (iii) mixed--sperm were centrifuged and resuspended in the luminal fluid of the other organ; (iv) no luminal fluid--sperm were centrifuged and reconstituted in buffer. All four experiments were performed without (controls) and with divalent cations (resulting in SCF). For each experimental condition, two different mice were used and the analyses averaged. DNA damage by SCF was analyzed by three different methods, the sperm chromatin structure assay (SCSA), terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) analysis and field inversion gel electrophoresis. In all three assays that we used, the vas deferens luminal fluid was much more efficient in stimulating SCF in the sperm from either source than that of the epididymis (P sperm were capable of initiating lower levels of SCF in the absence of luminal fluid (P sperm during their transit providing a mechanism to degrade the DNA. We

  2. Luminous Efficiency of Hypervelocity Meteoroid Impacts on the Moon Derived from the 2015 Geminid Meteor Shower

    Science.gov (United States)

    Moser, D. E.; Suggs, R. M.; Ehlert, S. R.

    2017-01-01

    Meteoroids cannot be observed directly because of their small size. In-situ measurements of the meteoroid environment are rare and have very small collecting areas. The Moon, in contrast, has a large collecting area and therefore can be used as a large meteoroid detector for gram-kilogram sized particles. Meteoroids striking the Moon create an impact flash observable by Earth-based telescopes. Their kinetic energy is converted to luminous energy with some unknown luminous efficiency ?(v), which is likely a function of meteoroid velocity (among other factors). This luminous efficiency is imperative to calculating the kinetic energy and mass of the meteoroid, as well as meteoroid fluxes, and it cannot be determined in the laboratory at meteoroid speeds and sizes due to mechanical constraints. Since laboratory simulations fail to resolve the luminous efficiency problem, observations of the impact flash itself must be utilized. Meteoroids associated with specific meteor showers have known speed and direction, which simplifies the determination of the luminous efficiency. NASA has routinely monitored the Moon for impact flashes since early 2006 [1]. During this time, several meteor showers have produced multiple impact flashes on the Moon, yielding a sufficient sample of impact flashes with which to perform a luminous efficiency analysis similar to that outlined in Bellot Rubio et al. [2, 3] and further described by Moser et al. [4], utilizing Earth-based measurements of the shower flux and mass index. The Geminid meteor shower has produced the most impact flashes in the NASA dataset to date with over 80 detections. More than half of these Geminids were recorded in 2015 (locations pictured in Fig. 1), and may represent the largest single-shower impact flash sample known. This work analyzes the 2015 Geminid lunar impacts and calculates their luminous efficiency. The luminous efficiency is then applied to calculate the kinetic energies and mass-es of these shower

  3. Absorption-Free Sub- and Super-Luminal Light Propagation via Quantum Interference

    Science.gov (United States)

    Wu, Jian-Chun; Liu, Zheng-Dong; Zheng, Jun

    2012-10-01

    We investigate the dispersive and absorptive properties of an N-type four-level atomic system in three coherent fields, and consider the susceptibility mathematically. It is shown that the group velocity of the probe field exhibits sub- and super-luminal under some conditions, meanwhile the absorption coefficient keeps zero during the occurrence and transition process of sub- and super-luminal pulses.

  4. Prognostic significance of progesterone receptor-positive tumor cells within immunohistochemically defined luminal A breast cancer.

    Science.gov (United States)

    Prat, Aleix; Cheang, Maggie Chon U; Martín, Miguel; Parker, Joel S; Carrasco, Eva; Caballero, Rosalía; Tyldesley, Scott; Gelmon, Karen; Bernard, Philip S; Nielsen, Torsten O; Perou, Charles M

    2013-01-10

    Current immunohistochemical (IHC)-based definitions of luminal A and B breast cancers are imperfect when compared with multigene expression-based assays. In this study, we sought to improve the IHC subtyping by examining the pathologic and gene expression characteristics of genomically defined luminal A and B subtypes. Gene expression and pathologic features were collected from primary tumors across five independent cohorts: British Columbia Cancer Agency (BCCA) tamoxifen-treated only, Grupo Español de Investigación en Cáncer de Mama 9906 trial, BCCA no systemic treatment cohort, PAM50 microarray training data set, and a combined publicly available microarray data set. Optimal cutoffs of percentage of progesterone receptor (PR) -positive tumor cells to predict survival were derived and independently tested. Multivariable Cox models were used to test the prognostic significance. Clinicopathologic comparisons among luminal A and B subtypes consistently identified higher rates of PR positivity, human epidermal growth factor receptor 2 (HER2) negativity, and histologic grade 1 in luminal A tumors. Quantitative PR gene and protein expression were also found to be significantly higher in luminal A tumors. An empiric cutoff of more than 20% of PR-positive tumor cells was statistically chosen and proved significant for predicting survival differences within IHC-defined luminal A tumors independently of endocrine therapy administration. Finally, no additional prognostic value within hormonal receptor (HR) -positive/HER2-negative disease was observed with the use of the IHC4 score when intrinsic IHC-based subtypes were used that included the more than 20% PR-positive tumor cells and vice versa. Semiquantitative IHC expression of PR adds prognostic value within the current IHC-based luminal A definition by improving the identification of good outcome breast cancers. The new proposed IHC-based definition of luminal A tumors is HR positive/HER2 negative/Ki-67 less than 14

  5. Lightness perception in high dynamic range images: local and remote luminance effects.

    Science.gov (United States)

    Allred, Sarah R; Radonjic, Ana; Gilchrist, Alan L; Brainard, David H

    2012-02-08

    We measured the perceived lightness of target patches embedded in high dynamic range checkerboards. We independently varied the luminance of checks immediately surrounding the test and those remote from it. The data establish context transfer functions (CTFs) that characterize perceptual matches across checkerboard contexts. Several features of the CTFs are broadly consistent with previous research: Matched luminance decreases when overall context luminance decreases; matched luminance increases when overall context luminance increases; manipulating context locations near the target has a greater effect than manipulating locations far from the target patch. The measured CTFs are not well described, however, by changes with context in multiplicative gain alone or by changes in both multiplicative and subtractive adaptation parameters. We were able to fit the data with a three-parameter model of adaptation. This allowed us to characterize the CTFs by specifying the luminances that appeared white, black, and gray (white point, black point, and gray point, respectively). The white and black points depended additively on the local and remote contrasts, but accounting for the gray point required an interaction term. Analysis of this effect suggests that the target patch itself must be included in a description of the visual context.

  6. Mercury-free electrodeless discharge lamp: effect of xenon pressure and plasma parameters on luminance

    Science.gov (United States)

    Ahmad, Nazri Dagang; Kondo, Akira; Motomura, Hideki; Jinno, Masafumi

    2009-05-01

    Since there is much concern about environmental preservation, the authors have paid attention to the uses of mercury in lighting application. They have focused on the application of the xenon low-pressure inductively coupled plasma (ICP) discharge in developing cylindrical type mercury-free light sources. ICP can be operated at low filling gas pressures and demonstrates significant potential in producing high density plasma. Xenon pressure was varied from 0.1 to 100 Torr and the lamp luminance was measured. The gas pressure dependence shows an increase in luminance at pressures below 1 Torr. In order to clarify this behaviour, measurement of plasma parameters was carried out using the double probe method and its relation to lamp luminance is discussed. As the gas pressure is decreased (from 1 to 0.01 Torr), the electron temperature increases while the electron density decreases while at the same time the lamp luminance increases. There are several factors that are believed to contribute to the increase in luminance in the very low pressure region. Increases in luminance are considered to be due to the electron-ion recombination process which brings a strong recombination radiation in continuum in the visible region and also due to the effect of stochastic heating.

  7. Basal cell signaling by p63 controls luminal progenitor function and lactation via NRG1

    Science.gov (United States)

    Forster, Nicole; Saladi, Srinivas Vinod; van Bragt, Maaike; Sfondouris, Mary E.; Jones, Frank E.; Li, Zhe; Ellisen, Leif W.

    2014-01-01

    Summary The mammary epithelium is organized as a bi-layer of luminal and basal/myoepithelial cells. During pregnancy the luminal compartment expands for milk production, while basal cells are thought to provide structural and contractile support. Here we reveal an unanticipated, pregnancy-specific role of basal epithelia as a central coordinator of lactogenesis. We demonstrate that genetic deletion of the transcription factor p63 (Trp63) gene exclusively within basal cells of the adult gland during pregnancy leads to dramatic defects in luminal cell proliferation and differentiation, resulting in lactation failure. This phenotype is explained by direct transcriptional activation of the EGF-family ligand gene Nrg1 by p63 selectively in basal cells, which is required for luminal ERBB4/STAT5A activation and consequent luminal progenitor cell maturation. Thus, paracrine basal-to-luminal cell signaling, controlled by p63 via NRG1, orchestrates the entire lactation program. Collectively, these findings redefine the paradigm for cellular interactions specifying the functional maturation of the mammary gland. PMID:24412575

  8. Competition between color and luminance for target selection in smooth pursuit and saccadic eye movements.

    Science.gov (United States)

    Spering, Miriam; Montagnini, Anna; Gegenfurtner, Karl R

    2008-11-24

    Visual processing of color and luminance for smooth pursuit and saccadic eye movements was investigated using a target selection paradigm. In two experiments, stimuli were varied along the dimensions color and luminance, and selection of the more salient target was compared in pursuit and saccades. Initial pursuit was biased in the direction of the luminance component whereas saccades showed a relative preference for color. An early pursuit response toward luminance was often reversed to color by a later saccade. Observers' perceptual judgments of stimulus salience, obtained in two control experiments, were clearly biased toward luminance. This choice bias in perceptual data implies that the initial short-latency pursuit response agrees with perceptual judgments. In contrast, saccades, which have a longer latency than pursuit, do not seem to follow the perceptual judgment of salience but instead show a stronger relative preference for color. These substantial differences in target selection imply that target selection processes for pursuit and saccadic eye movements use distinctly different weights for color and luminance stimuli.

  9. Increasing luminous efficiency of led by joint dimming mode with adjustable peak current

    Directory of Open Access Journals (Sweden)

    Li Yongtao

    2016-01-01

    Full Text Available Luminous efficiency and color temperature of LED chip are affected by current and temperature. PWM dimming mode only works at two kinds of current levels-rated current and zero current. It has smaller effect on color temperature compared with linear dimming mode, but it will reduce the luminous efficiency of lamps. Linear dimming mode has higher luminous efficiency by comparison. The two dimming modes above cannot keep color temperature stable and Luminous efficiency high. Therefore, the paper designed a joint dimming mode by integrating advantages of the two modes. The dimming method not only adjusts peak current, but also changes the duty cycle of dimming signals. The injected average current is kept stable by reducing peak current and increasing the duty cycle. The decreased luminous efficiency by the raise of temperature was made up for. Then according to the mathematical model of total flux and current, the author calculates the mathematical mode of flux affected by temperature. It proves the fact that adjusting peak current slightly can compensates for the reduced luminous efficiency affected by temperature through theoretical calculation. In addition, the final peak current after calculation can contribute to the adjustment parameter of joint dimming modes.

  10. Distributions of sky luminance and radiance of North Bangkok under standard distributions

    Energy Technology Data Exchange (ETDEWEB)

    Chirarattananon, Surapong; Chaiwiwatworakul, Pipat [Energy Field of Study, Asian Institute of Technology, P.O. Box 4, Klong Luang, Pathum Thani, Thailand 12120 (Thailand)

    2007-07-15

    In the tropics, the sky is luminous and variable. Distribution of luminance over the sky dome is non-uniform and varies widely and dynamically with weather condition. The high luminosity offers good potential for daylighting, but an understanding of the luminance distribution of tropical sky would help advance the movement for daylighting. This paper reports results of a characterization of sky luminance and radiance under the standard sky luminance patterns proposed by Kittler using measurements from a station located north of Bangkok. In accordance to the standard sky luminance classification, the sky patterns of north Bangkok mostly fall into clear and intermediate types. During cooler months, the sky is clear for over 60% of the time. In the midst of the rainy season, the sky falls into the intermediate category for over 40% of the time. The high incidence of clear sky on this classification differs from earlier results that use sky ratio and Perez's clearness indices in the classification of sky condition. (author)

  11. Luminance information decoding on the basis of local field potential signals of pigeon optic tectum neurons.

    Science.gov (United States)

    Wang, Songwei; Liu, Lijun; Wang, Zhizhong; Niu, Xiaoke; Hu, Yuxia; Shi, Li

    2017-11-08

    Important aspects of brain information processing can be understood by examining decoding of visual stimuli from neuronal response signals. In this research, the luminance information is decoded from the local field potential signal in the optic tectum region of the pigeon. We designed a luminance visual stimulus model with transient flicker characteristics, recorded multichannel local field potential (LFP) signals using a microelectrode array, extracted LFP Fourier transform energy and phase features, constructed a multivariate linear inverse filter luminance information decoding algorithm, and evaluated decoding effects using a cross-correlation method. We found that LFP signal phase decoding of luminance information yielded better effects than amplitude decoding of luminance information. In the case of optimal frequency band, channels, delay time, and other parameters, the results of phase and amplitude codecoding could reach 0.94±0.02. Comparing the differences between neuronal spike decoding and LFP decoding, we found that LFP signal phase and amplitude codecoding resulted in luminance closer to that of the actual stimulus and required fewer decoding electrode channels.

  12. Mercury-free electrodeless discharge lamp: effect of xenon pressure and plasma parameters on luminance

    Energy Technology Data Exchange (ETDEWEB)

    Nazri Dagang Ahmad; Kondo, Akira; Motomura, Hideki; Jinno, Masafumi, E-mail: nazri@mayu.ee.ehime-u.ac.j [Department of Electrical and Electronic Engineering, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577 (Japan)

    2009-05-07

    Since there is much concern about environmental preservation, the authors have paid attention to the uses of mercury in lighting application. They have focused on the application of the xenon low-pressure inductively coupled plasma (ICP) discharge in developing cylindrical type mercury-free light sources. ICP can be operated at low filling gas pressures and demonstrates significant potential in producing high density plasma. Xenon pressure was varied from 0.1 to 100 Torr and the lamp luminance was measured. The gas pressure dependence shows an increase in luminance at pressures below 1 Torr. In order to clarify this behaviour, measurement of plasma parameters was carried out using the double probe method and its relation to lamp luminance is discussed. As the gas pressure is decreased (from 1 to 0.01 Torr), the electron temperature increases while the electron density decreases while at the same time the lamp luminance increases. There are several factors that are believed to contribute to the increase in luminance in the very low pressure region. Increases in luminance are considered to be due to the electron-ion recombination process which brings a strong recombination radiation in continuum in the visible region and also due to the effect of stochastic heating.

  13. The most luminous z ∼ 9-10 galaxy candidates yet found: The luminosity function, cosmic star-formation rate, and the first mass density estimate at 500 Myr

    Energy Technology Data Exchange (ETDEWEB)

    Oesch, P. A.; Illingworth, G. D.; Magee, D. [UCO/Lick Observatory, University of California, Santa Cruz, 1156 High St, Santa Cruz, CA 95064 (United States); Bouwens, R. J.; Labbé, I.; Smit, R.; Franx, M. [Leiden Observatory, Leiden University, NL-2300 RA Leiden (Netherlands); Van Dokkum, P. G.; Momcheva, I. [Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06520 (United States); Ashby, M. L. N.; Fazio, G. G.; Huang, J.-S.; Willner, S. P. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Gonzalez, V. [University of California, Riverside, 900 University Ave, Riverside, CA 92507 (United States); Trenti, M. [Institute of Astronomy and Kavli Institute for Cosmology, University of Cambridge, Cambridge CB3 0HA (United Kingdom); Brammer, G. B. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Skelton, R. E. [South African Astronomical Observatory, P.O. Box 9, Observatory 7935 (South Africa); Spitler, L. R., E-mail: pascal.oesch@yale.edu [Department of Physics and Astronomy, Faculty of Sciences, Macquarie University, Sydney, NSW 2109 (Australia)

    2014-05-10

    We present the discovery of four surprisingly bright (H {sub 160} ∼ 26-27 mag AB) galaxy candidates at z ∼ 9-10 in the complete HST CANDELS WFC3/IR GOODS-N imaging data, doubling the number of z ∼ 10 galaxy candidates that are known, just ∼500 Myr after the big bang. Two similarly bright sources are also detected in a reanalysis of the GOODS-S data set. Three of the four galaxies in GOODS-N are significantly detected at 4.5σ-6.2σ in the very deep Spitzer/IRAC 4.5 μm data, as is one of the GOODS-S candidates. Furthermore, the brightest of our candidates (at z = 10.2 ± 0.4) is robustly detected also at 3.6 μm (6.9σ), revealing a flat UV spectral energy distribution with a slope β = –2.0 ± 0.2, consistent with demonstrated trends with luminosity at high redshift. Thorough testing and use of grism data excludes known low-redshift contamination at high significance, including single emission-line sources, but as-yet unknown low redshift sources could provide an alternative solution given the surprising luminosity of these candidates. Finding such bright galaxies at z ∼ 9-10 suggests that the luminosity function for luminous galaxies might evolve in a complex way at z > 8. The cosmic star formation rate density still shows, however, an order-of-magnitude increase from z ∼ 10 to z ∼ 8 since the dominant contribution comes from low-luminosity sources. Based on the IRAC detections, we derive galaxy stellar masses at z ∼ 10, finding that these luminous objects are typically 10{sup 9} M {sub ☉}. This allows for a first estimate of the cosmic stellar mass density at z ∼ 10 resulting in log{sub 10} ρ{sub ∗}=4.7{sub −0.8}{sup +0.5} M {sub ☉} Mpc{sup –3} for galaxies brighter than M {sub UV} ∼ –18. The remarkable brightness, and hence luminosity, of these z ∼ 9-10 candidates will enable deep spectroscopy to determine their redshift and nature, and highlights the opportunity for the James Webb Space Telescope to map the buildup of

  14. Near-Infrared Coloring via a Contrast-Preserving Mapping Model.

    Science.gov (United States)

    Chang-Hwan Son; Xiao-Ping Zhang

    2017-11-01

    Near-infrared gray images captured along with corresponding visible color images have recently proven useful for image restoration and classification. This paper introduces a new coloring method to add colors to near-infrared gray images based on a contrast-preserving mapping model. A naive coloring method directly adds the colors from the visible color image to the near-infrared gray image. However, this method results in an unrealistic image because of the discrepancies in the brightness and image structure between the captured near-infrared gray image and the visible color image. To solve the discrepancy problem, first, we present a new contrast-preserving mapping model to create a new near-infrared gray image with a similar appearance in the luminance plane to the visible color image, while preserving the contrast and details of the captured near-infrared gray image. Then, we develop a method to derive realistic colors that can be added to the newly created near-infrared gray image based on the proposed contrast-preserving mapping model. Experimental results show that the proposed new method not only preserves the local contrast and details of the captured near-infrared gray image, but also transfers the realistic colors from the visible color image to the newly created near-infrared gray image. It is also shown that the proposed near-infrared coloring can be used effectively for noise and haze removal, as well as local contrast enhancement.

  15. Infrared Detectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The end goal of this project is to develop proof-of-concept infrared detectors which can be integrated in future infrared instruments engaged in remote...

  16. Feldspar, Infrared Stimulated Luminescence

    DEFF Research Database (Denmark)

    Jain, Mayank

    2014-01-01

    This entry primarily concerns the characteristics and the origins of infrared-stimulated luminescence in feldspars.......This entry primarily concerns the characteristics and the origins of infrared-stimulated luminescence in feldspars....

  17. Strong magnetic fields in normal galaxies at high redshift

    Science.gov (United States)

    Bernet, Martin L.; Miniati, Francesco; Lilly, Simon J.; Kronberg, Philipp P.; Dessauges-Zavadsky, Miroslava

    2008-07-01

    The origin and growth of magnetic fields in galaxies is still something of an enigma. It is generally assumed that seed fields are amplified over time through the dynamo effect, but there are few constraints on the timescale. It was recently demonstrated that field strengths as traced by rotation measures of distant (and hence ancient) quasars are comparable to those seen today, but it was unclear whether the high fields were in the unusual environments of the quasars themselves or distributed along the lines of sight. Here we report high-resolution spectra that demonstrate that the quasars with strong MgII absorption lines are unambiguously associated with larger rotation measures. Because MgII absorption occurs in the haloes of normal galaxies along the sightlines to the quasars, this association requires that organized fields of surprisingly high strengths are associated with normal galaxies when the Universe was only about one-third of its present age.

  18. Nature of the Background Ultraviolet Radiation Field at High Redshifts

    Indian Academy of Sciences (India)

    tribpo

    thus necessary for the understanding of the early universe. AGNs are believed to be the major ... This ratio is insensitive to the particle density and the abundance of carbon, but is very sensitive to the ..... assuming the rest of the required flux to be of local, galactic origin, very high galactic flux is required. For most of the ...

  19. From Nearby Low Luminosity AGN to High Redshift Radio Galaxies ...

    Indian Academy of Sciences (India)

    Amity Institute of Applied Sciences, Amity University Uttar Pradesh, Sector-125, Noida, India. Astronomy & Astrophysics Division, Physical Research Laboratory, Ahmedabad 380 009, India. Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560 080, India. Centre de Recherche Astrophysique de ...

  20. Predicting the High Redshift Galaxy Population for JWST

    Science.gov (United States)

    Flynn, Zoey; Benson, Andrew

    2017-01-01

    The James Webb Space Telescope will be launched in Oct 2018 with the goal of observing galaxies in the redshift range of z = 10 - 15. As redshift increases, the age of the Universe decreases, allowing us to study objects formed only a few hundred million years after the Big Bang. This will provide a valuable opportunity to test and improve current galaxy formation theory by comparing predictions for mass, luminosity, and number density to the observed data. We have made testable predictions with the semi-analytical galaxy formation model Galacticus. The code uses Markov Chain Monte Carlo methods to determine viable sets of model parameters that match current astronomical data. The resulting constrained model was then set to match the specifications of the JWST Ultra Deep Field Imaging Survey. Predictions utilizing up to 100 viable parameter sets were calculated, allowing us to assess the uncertainty in current theoretical expectations. We predict that the planned UDF will be able to observe a significant number of objects past redshift z > 9 but nothing at redshift z > 11. In order to detect these faint objects at redshifts z = 11-15 we need to increase exposure time by at least a factor of 1.66.

  1. Are high-redshift quasars hidden by dusty galaxies?

    Science.gov (United States)

    Wright, Edward L.

    1990-04-01

    A Monte Carlo technique has been developed to compute the joint probability distribution for the reddening and extinction of quasars by galaxies along the line of sight with a realistic dust extinction curve including the 220 nm feature. Galaxies are treated as disks with random inclinations, having exponential or modified Gaussian radial profiles. This technique is used to find the distribution of the reddened quasars on multicolor diagrams such as the (U-J, J-F) plots used by Koo and Kron (1982) to find faint quasars. The multicolor search technique is not a simple UV excess approach, and the resulting color selection does not add significantly to the flux selection discussed by Wright (1981), Ostriker and Heisler (1984), and Heisler and Ostriker (1988). The quasar reddening trend observed by Wright and Malkan (1987) is about 0.35 + or - 0.50 times the mean reddening of the selected sample predicted by the Heisler and Ostriker model.

  2. On the Number of Galaxies at High Redshift

    Directory of Open Access Journals (Sweden)

    Lorenzo Zaninetti

    2015-09-01

    Full Text Available The number of galaxies at a given flux as a function of the redshift, z, is derived when the z-distance relation is non-standard. In order to compare different models, the same formalism is also applied to the standard cosmology. The observed luminosity function for galaxies of the zCOSMOS catalog at different redshifts is modeled by a new luminosity function for galaxies, which is derived by the truncated beta probability density function. Three astronomical tests, which are the photometric maximum as a function of the redshift for a fixed flux, the mean value of the redshift for a fixed flux, and the luminosity function for galaxies as a function of the redshift, compare the theoretical values of the standard and non-standard model with the observed value. The tests are performed on the FORS Deep Field (FDF catalog up to redshift z = 1.5 and on the zCOSMOS catalog extending beyond z = 4. These three tests show minimal differences between the standard and the non-standard models.

  3. Stellar Population Maps of High-Redshift Galaxies

    Science.gov (United States)

    Fetherolf, Tara; Reddy, Naveen; MOSDEF

    2016-06-01

    A comprehensive study of resolved galaxy structure can shed light on the formation and evolution of galactic properties, such as the distribution of stars and interstellar dust that obscures starlight. This requires high-resolution, multi-waveband photometry and spectroscopy to completely characterize the galaxies. Previous studies lacked key spectroscopic information, were comprised of small samples, or focused on the local universe. We use HST ACS/WFC3 high-resolution, multi-waveband imaging from the CANDELS project in parallel with moderate-resolution Keck I MOSFIRE spectra from the MOSFIRE Deep Evolution Field (MOSDEF) survey to produce resolved stellar population and dust maps of ~500 galaxies at redshifts 1.4 < z < 2.6—covering the key epoch when galaxies accreted most of their mass. For data preparation and analysis we develop an automated Python program to process our large, comprehensive dataset. From the multi-waveband imaging and spectroscopic redshifts, we model the spectral energy distribution for every resolution element within each galaxy and compare these results to the spectroscopically measured global properties. From our stellar population and dust maps we identify resolved structures within these galaxies. We also investigate if spectroscopically measured galaxy properties are biased when compared with that of localized sub-galactic structures.

  4. Stellar populations a guide from low to high redshift

    CERN Document Server

    Renzini, Alvio

    2011-01-01

    This up-to-date reference on stellar populations and development models includes coverage of distant galaxies, chemical evolution and supernovae. Written by highly acclaimed authorities in the field, the book makes use of specific problems to reveal the ""kitchen secrets.""

  5. High-Redshift Radio Galaxies from Deep Fields

    Indian Academy of Sciences (India)

    2016-01-27

    2. National Centre for Radio Astrophysics, Post Bag No. 3, Ganeshkind, Pune 411 007, India. International Centre for Radio Astronomical Research, University of Western Australia, Perth, Western Australia, Australia.

  6. Calan Tololo Survey: Bright Quasars at High Redshifts

    Science.gov (United States)

    Maza, Jose; Ruiz, Maria Teresa; Gonzalez, Luis E.; Wischnjewsky, Marina

    An objective prism survey has been started at Cerro Tololo Inter-American Observatory using the thin UV prism (1,360 Å/mm at Hγ and 1,740 Å/mm at Hβ) on the Curtis Schmidt telescope. Unfiltered baked IIIaJ plates exposed 90 minutes have been obtained for 163 fields. Unwiden spectra taken in good seeing reach B ≅ 19. This survey is an extension of the original Tololo survey (Smith 1975; Smith, Aguirre and Zemelman 1986).

  7. Radio imaging of core-dominated high redshift quasars

    NARCIS (Netherlands)

    Barthel, PD; Vestergaard, M; Lonsdale, CJ

    VLA imaging at kiloparsec-scale resolution of sixteen core-dominated radio-loud QSOs is presented. Many;objects appear to display variable radio emission and their radio morphologies are significantly smaller than those of steep-spectrum quasars, consistent with these objects being observed at sight

  8. Simulating the [CII] emission of high redshift galaxies

    DEFF Research Database (Denmark)

    Olsen, Karen Pardos; Greve, Thomas Rodriguez; Narayanan, Desika

    2016-01-01

    and radiative transfer, the photoionization code CLOUDY isimplemented. I will show results for z=2 star-forming galaxies yet to beobserved, as well as preliminary results for galaxies at z~6-7 whereobservations have presented contradictory detections and non-detectionsof star-forming galaxies.......he fine structure line of [CII] at 158 microns can arise throughout theinterstellar medium (ISM) and has been proposed as a tracer of starformation rate (SFR). But the origin of [CII] and how it depends on e.g.metallicity and radiation field of a galaxy remain uncertain.Simulating[CII] can be done...... by combining the output from galaxy simulations withprescriptions for the subgrid physics, as has now been demonstrated byseveral groups. However, these models are either built on analyticaldiscs or contain other simplifying assumptions. SÍGAME (Simulatorof GAlaxy Millimeter/submillimeter emission) avoids...

  9. Simulating the [CII] emission of high redshift galaxies

    DEFF Research Database (Denmark)

    Pardos Olsen, Karen; Greve, Thomas Rodriguez; Narayanan, Desika

    2016-01-01

    The fine structure line of [CII] at 158 microns can arise throughout the interstellar medium (ISM) and has been proposed as a tracer of star formation rate (SFR). But the origin of [CII] and how it depends on e.g. metallicity and radiation field of a galaxy remain uncertain.Simulating [CII] can...... be done by combining the output from galaxy simulations with prescriptions for the subgrid physics, as has now been demonstrated by several groups. However, these models are either built on analytical discs or contain other simplifying assumptions. SÍGAME (Simulator of GAlaxy Millimeter....../submillimeter emission) avoids these issues by using cosmological simulations and calculates [CII] emission reliably on resolved scales within each galaxy. The local metallicity is that of the simulation, whereas the far-ultraviolet radiation field and cosmic ray intensity are both scaled with local star formation rate...

  10. From Nearby Low Luminosity AGN to High Redshift Radio Galaxies ...

    Indian Academy of Sciences (India)

    'radio-quiet' AGN (Croton et al. 2006; Best & Heckman 2012). There is also evidence to suggest that galaxy mergers influence the radio-loudness of sources (Heckman et al. 1986; Deane et al. 2014). We know that galaxy mergers are an important phase of galaxy evolution (Schweizer 1982; Mihos & Hernquist. 1996; Cox et ...

  11. Kinematics of a high-redshift galaxy: A case study

    Directory of Open Access Journals (Sweden)

    Ćirković M.M.

    2000-01-01

    Full Text Available A kinematics of a z = 2.81 galaxy toward bright QSO 0528-250, as inferred from the absorption spectroscopy is discussed. There are sufficient arguments for a far-reaching conclusion that we are observing an older, uninvolved version of the local Galactic interstellar medium.

  12. A spectroscopic study of the high-redshift Universe

    NARCIS (Netherlands)

    Karman, Wouter

    2016-01-01

    Galaxies are systems in which stars are formed out of gas and dust. In each galaxy, millions to hundreds of billions of stars reside and evolve as time moves on. The first galaxies were probably formed as early as 200 million years after the Big Bang, in other words, 13.6 billion years ago. Young

  13. Was Star-Formation Suppressed in High-Redshift Minihalos?

    OpenAIRE

    Haiman, Zoltan; Bryan, Greg L.

    2006-01-01

    The primordial gas in the earliest dark matter halos, collapsing at redshifts around z=20, with masses M_halo=10^6 M_sun, and virial temperatures T_vir 10^4K). This conclusion is insensitive to assumptions about the efficiency of ionizing photon production in the large halos, as long as reionization ends by z=6, as required by the spectra of bright quasars at z

  14. Pair creation supernovae at low and high redshift

    NARCIS (Netherlands)

    Langer, N.|info:eu-repo/dai/nl/304829498; Norman, C.A.; de Koter, A.; Vink, J.|info:eu-repo/dai/nl/182880559; Cantiello, M.|info:eu-repo/dai/nl/304840866; Yoon, S.C.|info:eu-repo/dai/nl/266576753

    2007-01-01

    Aims:Pair creation supernovae (PCSN) are thought to be produced from very massive low metallicity stars. The spectacularly bright SN 2006gy does show several signatures expected from PCSNe. Here, we investigate the metallicity threshold below which PCSN can form and estimate their occurrence rate.

  15. Pair creation supernovae at low and high redshift

    NARCIS (Netherlands)

    Langer, N.; Norman, C.A.; de Koter, A.; Vink, J.S.; Cantiello, M.; Yoon, S.C.

    2007-01-01

    Aims.Pair creation supernovae (PCSN) are thought to be produced from very massive low metallicity stars. The spectacularly bright SN 2006gy does show several signatures expected from PCSNe. Here, we investigate the metallicity threshold below which PCSN can form and estimate their occurrence rate.

  16. FROM NEARBY LOW LUMINOSITY AGN TO HIGH REDSHIFT ...

    Indian Academy of Sciences (India)

    44

    galaxies exhibited primarily two radio morphologies: the. Fanaroff-Riley (FR) type I galaxies had broad jets that flared into diffuse radio plumes / lobes, while the FR type II galaxies had collimated jets that terminated in regions of high surface brightness called “hot spots” with the back-flowing plasma or the plasma left behind ...

  17. Radio imaging of core-dominated high redshift quasars

    DEFF Research Database (Denmark)

    Barthel, Peter D.; Vestergaard, Marianne; Lonsdale, Colin J.

    1999-01-01

    VLA imaging at kiloparsec-scale resolution of sixteen core-dominated radio-loud QSOs is presented. Many objects appear to display variable radio emission and their radio morphologies are significantly smaller than those of steep-spectrum quasars, consistent with these objects being observed...... at sight lines close to their (relativistic, $\\gamma \\approx$ 4-7) jet axes. The usefulness of the radio source orientation indicator R_V, being defined as ratio of radio core and rest frame optical V-band luminosity, is confirmed....

  18. High-Redshift Compton Thick AGN with EXIST

    Science.gov (United States)

    Treister, Ezequiel; Urry, C.; Coppi, P.; Virani, S.

    2009-01-01

    It has been suspected for many years that a large number of heavily obscured, Compton Thick, Active Galactic Nuclei (AGN) should exist at all redshifts, but the exact number of them is still highly uncertain. Recent all-sky surveys with INTEGRAL and Swift are starting to constrain the number of Compton Thick AGN in the local Universe, zEXIST observations. We expect to find a total of 120 Compton Thick AGN at 0.5

  19. DACH1: its role as a classifier of long term good prognosis in luminal breast cancer.

    Directory of Open Access Journals (Sweden)

    Desmond G Powe

    Full Text Available BACKGROUND: Oestrogen receptor (ER positive (luminal tumours account for the largest proportion of females with breast cancer. Theirs is a heterogeneous disease presenting clinical challenges in managing their treatment. Three main biological luminal groups have been identified but clinically these can be distilled into two prognostic groups in which Luminal A are accorded good prognosis and Luminal B correlate with poor prognosis. Further biomarkers are needed to attain classification consensus. Machine learning approaches like Artificial Neural Networks (ANNs have been used for classification and identification of biomarkers in breast cancer using high throughput data. In this study, we have used an artificial neural network (ANN approach to identify DACH1 as a candidate luminal marker and its role in predicting clinical outcome in breast cancer is assessed. MATERIALS AND METHODS: A reiterative ANN approach incorporating a network inferencing algorithm was used to identify ER-associated biomarkers in a publically available cDNA microarray dataset. DACH1 was identified in having a strong influence on ER associated markers and a positive association with ER. Its clinical relevance in predicting breast cancer specific survival was investigated by statistically assessing protein expression levels after immunohistochemistry in a series of unselected breast cancers, formatted as a tissue microarray. RESULTS: Strong nuclear DACH1 staining is more prevalent in tubular and lobular breast cancer. Its expression correlated with ER-alpha positive tumours expressing PgR, epithelial cytokeratins (CK18/19 and 'luminal-like' markers of good prognosis including FOXA1 and RERG (p<0.05. DACH1 is increased in patients showing longer cancer specific survival and disease free interval and reduced metastasis formation (p<0.001. Nuclear DACH1 showed a negative association with markers of aggressive growth and poor prognosis. CONCLUSION: Nuclear DACH1 expression

  20. MR measurement of luminal water in prostate gland: Quantitative correlation between MRI and histology.

    Science.gov (United States)

    Sabouri, Shirin; Fazli, Ladan; Chang, Silvia D; Savdie, Richard; Jones, Edward C; Goldenberg, S Larry; Black, Peter C; Kozlowski, Piotr

    2017-09-01

    To determine the relationship between parameters measured from luminal water imaging (LWI), a new magnetic resonance imaging (MRI) T2 mapping technique, and the corresponding tissue composition in prostate. In all, 17 patients with prostate cancer were examined with a 3D multiecho spin echo sequence at 3T prior to undergoing radical prostatectomy. Maps of seven MR parameters, called N, T2-short , T2-long , Ashort , Along , geometric mean T2 time (gmT2 ), and luminal water fraction (LWF), were generated using nonnegative least squares (NNLS) analysis of the T2 decay curves. MR parametric maps were correlated to digitized whole-mount histology sections. Percentage area of tissue components, including luminal space, nuclei, and cytoplasm plus stroma, was measured on the histology sections by using color-based image segmentation. Spearman's rank correlation test was used to evaluate the correlation between MR parameters and the corresponding tissue components, with particular attention paid to the correlation between LWF and percentage area of luminal space. N, T2-short , Along , gmT2 , and LWF showed significant correlation (P correlation (P correlation was observed between LWF and luminal space (Spearman's coefficient of rank correlation = 0.75, P correlated with the fractional amount of luminal space in prostatic tissue. This result suggests that LWI can potentially be applied for evaluation of prostatic diseases in which the extent of luminal space differs between normal and abnormal tissues. 1 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:861-869. © 2017 International Society for Magnetic Resonance in Medicine.

  1. The most luminous heavily obscured quasars have a high merger fraction: morphological study of wise -selected hot dust-obscured galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Lulu; Gao, Ying; Zhang, Dandan; Jiang, Xiaoming; Wu, Qiaoqian; Yang, Jun; Li, Zhao [Shandong Provincial Key Lab of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Science, Shandong University, Weihai 264209 (China); Han, Yunkun [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Fang, Guanwen, E-mail: llfan@sdu.edu.cn, E-mail: hanyk@ynao.ac.cn [Institute for Astronomy and History of Science and Technology, Dali University, Dali 671003 (China)

    2016-05-10

    Previous studies have shown that Wide-field Infrared Survey Explorer -selected hyperluminous, hot dust-obscured galaxies (Hot DOGs) are powered by highly dust-obscured, possibly Compton-thick active galactic nuclei (AGNs). High obscuration provides us a good chance to study the host morphology of the most luminous AGNs directly. We analyze the host morphology of 18 Hot DOGs at z ∼ 3 using Hubble Space Telescope /WFC3 imaging. We find that Hot DOGs have a high merger fraction (62 ± 14%). By fitting the surface brightness profiles, we find that the distribution of Sérsic indices in our Hot DOG sample peaks around 2, which suggests that most Hot DOGs have transforming morphologies. We also derive the AGN bolometric luminosity (∼10{sup 14} L {sub ⊙}) of our Hot DOG sample by using IR spectral energy distributions decomposition. The derived merger fraction and AGN bolometric luminosity relation is well consistent with the variability-based model prediction. Both the high merger fraction in an IR-luminous AGN sample and relatively low merger fraction in a UV/optical-selected, unobscured AGN sample can be expected in the merger-driven evolutionary model. Finally, we conclude that Hot DOGs are merger-driven and may represent a transit phase during the evolution of massive galaxies, transforming from the dusty starburst-dominated phase to the unobscured QSO phase.

  2. The effectiveness of a near-infrared vascular imaging device to support intravenous cannulation in children with dark skin color : a cluster randomized clinical trial

    NARCIS (Netherlands)

    van der Woude, Olga C P; Cuper, Natascha J; Getrouw, Chavalleh; Kalkman, Cor J; de Graaff, Jurgen C

    BACKGROUND: Poor vein visibility can make IV cannulation challenging in children with dark skin color. In the operating room, we studied the effectiveness of a near-infrared vascular imaging device (VascuLuminator) to facilitate IV cannulation in children with dark skin color. METHODS: In the

  3. Daylight luminance requirements for full-color, see-through, helmet-mounted display systems

    Science.gov (United States)

    Harding, Thomas H.; Rash, Clarence E.

    2017-05-01

    When color is implemented in helmet-mounted displays (HMDs) that are eyes-out, see-through displays, visual perception issues become an increased concern. A major confound with HMDs is their inherent see-through (transparent) property. The result is color in the displayed image that combines with color from the outside (or in-cockpit) world, producing an image with additive color. As luminance of the HMD imagery is reduced, the color separation between the HMD imagery and the background is also reduced. It is because of this additive effect that luminance contrast is so vitally important in developing HMD standards for color symbology. As a result, this paper identifies luminance requirements for full-color HMDs based upon two lines of investigation. The first is based on a study of white symbology against natural static backgrounds, where the quality of symbology was judged to be a function of not only the background luminance but also of the background complexity as well. The second is based on an evaluation of the complexity inherent in natural backgrounds and from this investigation, a predictive curve was found that describes the complexity of natural backgrounds as a function of ambient luminance.

  4. Intestinal alkaline phosphatase promotes gut bacterial growth by reducing the concentration of luminal nucleotide triphosphates.

    Science.gov (United States)

    Malo, Madhu S; Moaven, Omeed; Muhammad, Nur; Biswas, Brishti; Alam, Sayeda N; Economopoulos, Konstantinos P; Gul, Sarah Shireen; Hamarneh, Sulaiman R; Malo, Nondita S; Teshager, Abeba; Mohamed, Mussa M Rafat; Tao, Qingsong; Narisawa, Sonoko; Millán, José Luis; Hohmann, Elizabeth L; Warren, H Shaw; Robson, Simon C; Hodin, Richard A

    2014-05-15

    The intestinal microbiota plays a pivotal role in maintaining human health and well-being. Previously, we have shown that mice deficient in the brush-border enzyme intestinal alkaline phosphatase (IAP) suffer from dysbiosis and that oral IAP supplementation normalizes the gut flora. Here we aimed to decipher the molecular mechanism by which IAP promotes bacterial growth. We used an isolated mouse intestinal loop model to directly examine the effect of exogenous IAP on the growth of specific intestinal bacterial species. We studied the effects of various IAP targets on the growth of stool aerobic and anaerobic bacteria as well as on a few specific gut organisms. We determined the effects of ATP and other nucleotides on bacterial growth. Furthermore, we examined the effects of IAP on reversing the inhibitory effects of nucleotides on bacterial growth. We have confirmed that local IAP bioactivity creates a luminal environment that promotes the growth of a wide range of commensal organisms. IAP promotes the growth of stool aerobic and anaerobic bacteria and appears to exert its growth promoting effects by inactivating (dephosphorylating) luminal ATP and other luminal nucleotide triphosphates. We observed that compared with wild-type mice, IAP-knockout mice have more ATP in their luminal contents, and exogenous IAP can reverse the ATP-mediated inhibition of bacterial growth in the isolated intestinal loop. In conclusion, IAP appears to promote the growth of intestinal commensal bacteria by inhibiting the concentration of luminal nucleotide triphosphates. Copyright © 2014 the American Physiological Society.

  5. Lineage-Biased Stem Cells Maintain Estrogen-Receptor-Positive and -Negative Mouse Mammary Luminal Lineages

    Directory of Open Access Journals (Sweden)

    Chunhui Wang

    2017-03-01

    Full Text Available Delineating the mammary differentiation hierarchy is important for the study of mammary gland development and tumorigenesis. Mammary luminal cells are considered a major origin of human breast cancers. However, how estrogen-receptor-positive (ER+ and ER− luminal cells are developed and maintained remains poorly understood. The prevailing model suggests that a common stem/progenitor cell generates both cell types. Through genetic lineage tracing in mice, we find that SOX9-expressing cells specifically contribute to the development and maintenance of ER− luminal cells and, to a lesser degree, basal cells. In parallel, PROM1-expressing cells give rise only to ER+ luminal cells. Both SOX9+ and PROM1+ cells specifically sustain their respective lineages even after pregnancy-caused tissue remodeling or serial transplantation, demonstrating characteristic properties of long-term repopulating stem cells. Thus, our data reveal that mouse mammary ER+ and ER− luminal cells are two independent lineages that are maintained by distinct stem cells, providing a revised mammary epithelial cell hierarchy.

  6. 'Normalizing' the malignant phenotype of luminal breast cancer cells via alpha(v)beta(3)-integrin.

    Science.gov (United States)

    Abu-Tayeh, Hanan; Weidenfeld, Keren; Zhilin-Roth, Alisa; Schif-Zuck, Sagi; Thaler, Sonja; Cotarelo, Cristina; Tan, Tuan Z; Thiery, Jean P; Green, Jeffrey E; Klorin, Geula; Sabo, Edmond; Sleeman, Jonathan P; Tzukerman, Maty; Barkan, Dalit

    2016-12-01

    Reestablishing tissue organization of breast cancer cells into acini was previously shown to override their malignant phenotype. In our study, we demonstrate that alpha(v)beta(3) integrin (Int-αvβ3), previously shown to play a role in cancer progression, promoted differentiation and growth arrest of organoids derived from luminal A breast cancer cells grown in their relevant three-dimensional microenvironment. These organoids differentiated into normal-like acini resembling a benign stage of breast tissue. Likewise, we demonstrate that Int-αvβ3 is selectively expressed in the epithelium of the benign stage of breast tissues, and is lost during the early stages of luminal A breast cancer progression. Notably, the organoids' reversion into normal-like acini was mediated by cancer luminal progenitor-like cells expressing both EpCAM(high)CD49f(low)CD24(+) and Int-αvβ3. Furthermore, downregulation of Notch4 expression and downstream signaling was shown to mediate Int-αvβ3-induced reversion. Intriguingly, when luminal A breast cancer cells expressing Int-αvβ3 were injected into a humanized mouse model, differentiated tumors developed when compared with that generated by control cells. Hence, our data suggest that promoting differentiation of luminal A breast cancer cells by signaling emanating from Int-αvβ3 can potentially promote 'normalization' of their malignant phenotype and may prevent the malignant cells from progressing.

  7. Breaking object correspondence across saccades impairs object recognition: The role of color and luminance.

    Science.gov (United States)

    Poth, Christian H; Schneider, Werner X

    2016-09-01

    Rapid saccadic eye movements bring the foveal region of the eye's retina onto objects for high-acuity vision. Saccades change the location and resolution of objects' retinal images. To perceive objects as visually stable across saccades, correspondence between the objects before and after the saccade must be established. We have previously shown that breaking object correspondence across the saccade causes a decrement in object recognition (Poth, Herwig, & Schneider, 2015). Color and luminance can establish object correspondence, but it is unknown how these surface features contribute to transsaccadic visual processing. Here, we investigated whether changing the surface features color-and-luminance and color alone across saccades impairs postsaccadic object recognition. Participants made saccades to peripheral objects, which either maintained or changed their surface features across the saccade. After the saccade, participants briefly viewed a letter within the saccade target object (terminated by a pattern mask). Postsaccadic object recognition was assessed as participants' accuracy in reporting the letter. Experiment A used the colors green and red with different luminances as surface features, Experiment B blue and yellow with approximately the same luminances. Changing the surface features across the saccade deteriorated postsaccadic object recognition in both experiments. These findings reveal a link between object recognition and object correspondence relying on the surface features colors and luminance, which is currently not addressed in theories of transsaccadic perception. We interpret the findings within a recent theory ascribing this link to visual attention (Schneider, 2013).

  8. Detection of between-eye differences in color: Interactions with luminance.

    Science.gov (United States)

    Jennings, Ben J; Kingdom, Frederick A A

    2016-01-01

    Between-eye differences in color or luminance result in the appearance of luster, which provides a cue for detecting between-eye differences. We measured thresholds for detecting between-eye differences in both hue and chromatic contrast (saturation) in dichoptically superimposed color patches. Sensitivity was found to be highest at isoluminance and decreased with the addition of task-irrelevant, spatially coextensive, binocular (i.e., same in both eyes) luminance contrast. However, when the members of each dichoptic pair were presented side by side on the screen and viewed with the same eye, the added luminance contrast had no effect on the detection of their differences. If the effect of the luminance contrast was simply to dilute or desaturate the chromatic signals, we would expect thresholds to increase for the within-eye and not just the between-eye (dichoptic) conditions. We suggest that the presence of binocular luminance contrast reduces the interocular suppression between the dichoptic colors, causing the dichoptic color pairs to blend, thus rendering their differences harder to detect.

  9. Low luminance/eyes closed and monochromatic stimulations reduce variability of flash visual evoked potential latency.

    Science.gov (United States)

    Subramanian, Senthil Kumar; Gaur, Giriwar Singh; Narayan, Sunil K

    2013-10-01

    Visual evoked potentials are useful in investigating the physiology and pathophysiology of the human visual system. Flash visual evoked potential (FVEP), though technically easier, has less clinical utility because it shows great variations in both latency and amplitude for normal subjects. To study the effect of eye closure, low luminance, and monochromatic stimulation on the variability of FVEPs. Subjects in self-reported good health in the age group of 18-30 years were divided into three groups. All participants underwent FVEP recording with eyes open and with white light at 0.6 J luminance (standard technique). Next recording was done in group 1 with closed eyes, group 2 with 1.2 and 20 J luminance, and group 3 with red and blue lights, while keeping all the other parameters constant. Two trials were given for each eye, for each technique. The same procedure was repeated at the same clock time on the following day. Variation in FVEP latencies between the individuals (interindividual variability) and the variations within the same individual for four trials (intraindividual variability) were assessed using coefficient of variance (COV). The technique with lower COV was considered the better method. Recording done with closed eyes, 0.6 J luminance, and monochromatic light (blue > red) showed lower interindividual and intraindividual variability in P2 and N2 as compared to standard techniques. Low luminance flash stimulations and monochromatic light will reduce FVEP latency variability and may be clinically useful modifications of FVEP recording technique.

  10. Research on Methods of Infrared and Color Image Fusion Based on Wavelet Transform

    Directory of Open Access Journals (Sweden)

    Zhao Rentao

    2014-06-01

    Full Text Available There is significant difference in the imaging features of infrared image and color image, but their fusion images also have very good complementary information. In this paper, based on the characteristics of infrared image and color image, first of all, wavelet transform is applied to the luminance component of the infrared image and color image. In multi resolution the relevant regional variance is regarded as the activity measure, relevant regional variance ratio as the matching measure, and the fusion image is enhanced in the process of integration, thus getting the fused images by final synthesis module and multi-resolution inverse transform. The experimental results show that the fusion image obtained by the method proposed in this paper is better than the other methods in keeping the useful information of the original infrared image and the color information of the original color image. In addition, the fusion image has stronger adaptability and better visual effect.

  11. Luminous and Variable Stars in M31 and M33. IV. Luminous Blue Variables, Candidate LBVs, B[e] Supergiants, and the Warm Hypergiants: How to Tell Them Apart

    Science.gov (United States)

    Humphreys, Roberta M.; Gordon, Michael S.; Martin, John C.; Weis, Kerstin; Hahn, David

    2017-02-01

    In this series of papers we have presented the results of a spectroscopic survey of luminous stars in the nearby spirals M31 and M33. Here, we present spectroscopy of 132 additional stars. Most have emission-line spectra, including luminous blue variables (LBVs) and candidate LBVs, Fe II emission line stars, the B[e] supergiants, and the warm hypergiants. Many of these objects are spectroscopically similar and are often confused with each other. We examine their similarities and differences and propose the following guidelines that can be used to help distinguish these stars in future work. (1) The B[e] supergiants have emission lines of [O I] and [Fe II] in their spectra. Most of the spectroscopically confirmed sgB[e] stars also have warm circumstellar dust in their spectral energy distributions (SEDs). (2) Confirmed LBVs do not have the [O I] emission lines in their spectra. Some LBVs have [Fe II] emission lines, but not all. Their SEDs show free-free emission in the near-infrared but no evidence for warm dust. Their most important and defining characteristic is the S Dor-type variability. (3) The warm hypergiants spectroscopically resemble the LBVs in their dense wind state and the B[e] supergiants. However, they are very dusty. Some have [Fe II] and [O I] emission in their spectra like the sgB[e] stars, but are distinguished by their A- and F-type absorption-line spectra. In contrast, the B[e] supergiant spectra have strong continua and few if any apparent absorption lines. Candidate LBVs should share the spectral characteristics of the confirmed LBVs with low outflow velocities and the lack of warm circumstellar dust. Based on observations with the Multiple Mirror Telescope, a joint facility of the Smithsonian Institution and the University of Arizona and on observations obtained with the Large Binocular Telescope (LBT), an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are The University of

  12. Galaxy population properties of the massive X-ray luminous galaxy cluster XDCP J0044.0-2033 at z = 1.58. Red-sequence formation, massive galaxy assembly, and central star formation activity

    National Research Council Canada - National Science Library

    Fassbender, R; Nastasi, A; Santos, J. S; Lidman, C; Verdugo, M; Koyama, Y; Rosati, P; Pierini, D; Padilla, N; Romeo, A. D; Menci, N; Bongiorno, A; Castellano, M; Cerulo, P; Fontana, A; Galametz, A; Grazian, A; Lamastra, A; Pentericci, L; Sommariva, V; Strazzullo, V; Šuhada, R; Tozzi, P

    2014-01-01

    Context. Recent observational progress has enabled the detection of galaxy clusters and groups out to very high redshifts and for the first time allows detailed studies of galaxy population properties...

  13. LEDs on curved ceramic substrate with primary optics for modification of luminous intensity

    Science.gov (United States)

    Wei, An-Chi; Sze, Jyh-Rou; Chern, Jyh-Long

    2011-10-01

    Unlike the conventional LED luminary with a planar substrate and only the forward emission, the proposed LED luminary with a curved ceramic substrate can perform both the forward and the backward emissions. Assembled with the proper primary optics, an illustrated LED bulb has been designed, fabricated and measured. The measured luminous intensity of the LED bulb has shown the backward emission and designed distribution with the beam-angle of 133°. To broaden the application areas, such a LED bulb on a curved substrate has been modularized as a streetlight. The measured results of the proposed streetlight have shown that the beam angle of the luminous intensity and the luminaire efficiency are 132° and 86%, respectively. Meanwhile, its luminous characteristics also fit the standard for lighting design of urban roads.asei.c

  14. Properties of artificial neurons that report lightness based on accumulated experience with luminance

    Directory of Open Access Journals (Sweden)

    Yaniv eMorgenstern

    2014-11-01

    Full Text Available The responses of visual neurons in experimental animals have been extensively characterized. To ask whether these responses are consistent with a wholly empirical concept of visual perception, we optimized simple neural networks that respond according to the cumulative frequency of occurrence of local luminance patterns in retinal images. Based on this estimation of accumulated experience, the neuron responses showed classical center-surround receptive fields, luminance gain control and contrast gain control, the key properties of early level visual neurons determined in animal experiments. These results imply that a major purpose of pre-cortical neuronal circuitry is to contend with the inherently uncertain significance of luminance values in natural stimuli.

  15. Enhancing user experience by using multi-sensor data fusion to predict phone's luminance

    Science.gov (United States)

    Marhoubi, Asmaa H.

    2017-09-01

    The movement of a phone in an environment with different brightness, makes the luminance prediction challenging. The ambient light sensor takes time to modify the brightness of the screen based on the environment it is placed in. This causes an unsatisfactory user experience and delays in adjustment of the screen brightness. In this research, a method is proposed for enhancing the prediction of luminance using accelerometer, gyroscope and speed measurement technique. The speed of the phone is identified using Sum-of-Sine parameters. The lux values are then fused with the accelerometer and gyroscope data to present more accurate luminance values for the ALS based on the movement of the phone. An investigation is made during the movement of the user in a standard lighting environment. This enhances the user experience and improves the screen brightness precision. The accuracy has given an R-Square value of up to 0.97.

  16. Luminous Efficiency of Hypervelocity Meteoroid Impacts on the Moon Derived from the 2015 Geminid Meteor Shower

    Science.gov (United States)

    Moser, D. E.; Suggs, R. M.; Ehlert, S. R.

    2017-01-01

    Since early 2006 the Meteoroid Environment Office (MEO) at NASA's Marshall Space Flight Center has routinely monitored the Moon for impact flashes produced by meteoroids striking the lunar surface. Activity from the Geminid meteor shower (EM) was observed in 2015, resulting in the detection of 45 lunar impact flashes (roughly 10% of the NASA dataset), in about 10 hours of observation with peak R magnitudes ranging from 6.5 to 11. A subset of 30 of these flashes, observed 14-15 December, was analyzed in order to determine the luminous efficiency, the ratio of emitted luminous energy to the meteoroid's kinetic energy. The resulting luminous efficiency, found to range between n = 1.8 x 10(exp -4) and 3.3 x 10(exp -3), depending on the assumed mass index and flux, was than applied to calculate the masses of Geminid meteoroids striking the Moon in 2015.

  17. The histone chaperone HJURP is a new independent prognostic marker for luminal A breast carcinoma.

    Science.gov (United States)

    Montes de Oca, Rocío; Gurard-Levin, Zachary A; Berger, Frédérique; Rehman, Haniya; Martel, Elise; Corpet, Armelle; de Koning, Leanne; Vassias, Isabelle; Wilson, Laurence O W; Meseure, Didier; Reyal, Fabien; Savignoni, Alexia; Asselain, Bernard; Sastre-Garau, Xavier; Almouzni, Geneviève

    2015-03-01

    Breast cancer is a heterogeneous disease with different molecular subtypes that have varying responses to therapy. An ongoing challenge in breast cancer research is to distinguish high-risk patients from good prognosis patients. This is particularly difficult in the low-grade, ER-positive luminal A tumors, where robust diagnostic tools to aid clinical treatment decisions are lacking. Recent data implicating chromatin regulators in cancer initiation and progression offers a promising avenue to develop new tools to help guide clinical decisions. Here we exploit a published transcriptome dataset and an independent validation cohort to correlate the mRNA expression of selected chromatin regulators with respect to the four intrinsic breast cancer molecular subtypes. We then perform univariate and multivariate analyses to compare the prognostic value of a panel of chromatin regulators to Ki67, a currently utilized proliferation marker. Unsupervised hierarchical clustering revealed a gene cluster containing several histone chaperones and histone variants highly-expressed in the proliferative subtypes (basal-like, HER2-positive, luminal B) but not in the luminal A subtype. Several chromatin regulators, including the histone chaperones CAF-1 (subunits p150 and p60), ASF1b, and HJURP, and the centromeric histone variant CENP-A, associated with local and metastatic relapse and poor patient outcome. Importantly, we find that HJURP can discriminate favorable and unfavorable outcome within the luminal A subtype, outperforming the currently utilized proliferation marker Ki67, as an independent prognostic marker for luminal A patients. The integration of chromatin regulators as clinical biomarkers, in particular the histone chaperone HJURP, will help guide patient substratification and treatment options for low-risk luminal A breast carcinoma patients. Copyright © 2014. Published by Elsevier B.V.

  18. Variable luminal sarcoplasmic reticulum Ca(2+) buffer capacity in smooth muscle cells.

    Science.gov (United States)

    Dagnino-Acosta, Adán; Guerrero-Hernández, Agustín

    2009-09-01

    Sarcoplasmic reticulum contains the internal Ca(2+) store in smooth muscle cells and its lumen appears to be a continuum that lacks diffusion barriers. Accordingly, the free luminal Ca(2+) level is the same all throughout the SR; however, whether the Ca(2+) buffer capacity is the same in all the SR is unknown. We have estimated indirectly the luminal Ca(2+) buffer capacity of the SR by comparing the reduction in SR Ca(2+) levels with the corresponding increase in [Ca(2+)](i) during activation of either IP(3)Rs with carbachol or RyRs with caffeine, in smooth muscle cells from guinea pig urinary bladder. We have determined that carbachol-sensitive SR has a 2.4 times larger Ca(2+) buffer capacity than caffeine-sensitive SR. Rapid inhibition of SERCA pumps with thapsigargin revealed that this pump activity accounts for 80% and 60% of the Ca(2+) buffer capacities of carbachol- and caffeine-sensitive SR, respectively. Moreover, the Ca(2+) buffer capacity of carbachol-sensitive SR was similar to caffeine-sensitive SR when SERCA pumps were inhibited. Similar rates of Ca(2+) replenishments suggest similar levels of SERCA pump activities for either carbachol- or caffeine-sensitive SR. Paired pulses of caffeine, in conditions of low Ca(2+) influx, indicate the relevance of luminal SR Ca(2+) buffer capacity in the [Ca(2+)](i) response. To further study the importance of luminal SR Ca(2+) buffer capacity in the release process we used low levels of heparin to partially inhibit IP(3)Rs. This condition revealed carbachol-induced transient increase of luminal SR Ca(2+) levels provided that SERCA pumps were active. It thus appears that SERCA pump activity keeps the luminal SR Ca(2+)-binding proteins in the high-capacity, low-affinity conformation, particularly for IP(3)R-mediated Ca(2+) release.

  19. ["Glare vision". I. Physiological principles of vision change with increased test field luminance].

    Science.gov (United States)

    Hauser, B; Ochsner, H; Zrenner, E

    1992-02-01

    Clinical tests of visual acuity are an important measure of visual function. However visual acuity is usually determined only in narrow range of luminance levels between 160 and 320 cd/m2; therefore losses of visual acuity in other ranges of light intensity can not be detected. In a distance of 80 cm from the patients eyes, Landolt rings of varying sizes were presented on a small test field whose light intensity can be varied between 0.1 and 30,000 cd/m2. Thereby an acuity-luminance-function can be obtained. We studied such functions under different conditions of exposure time both with constant and with increasing luminance of the test field. We found that persons with normal vision can increase their visual acuity with increasing test field luminance up to a range of 5000 cd/m2. The maximum values of visual acuity under optimal lightening conditions lie (varying with age) between 2.2 and 0.9. Under pathological conditions visual acuity falls at high luminances accompanied by sensations of glare. Tests of glare sensitivity as a function of exposure time showed 4 sec to be a critical time of exposure since after 4 sec normal persons just reach their maximum visual acuity at high luminances. The underlying physiological mechanisms lead us to suppose that patients with neuronal light adaptation disturbances display a greater visual loss as a result of decreased time of exposure than those with disturbances in the ocular media. Visual acuity as well as the capacity to increase the patients visual acuity under optimal conditions of lighting were both found to be strongly age-dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. SPECIFIC CHARACTERISTICS OF BRAIN METASTASIZING IN PATIENTS WITH LUMINAL SUBTYPE OF BREAST CANCER

    Directory of Open Access Journals (Sweden)

    A. S. Balkanov

    2016-01-01

    Full Text Available Background: More than half of female patients with breast cancer are diagnosed with a  luminal subtype of the disease; however, specific characteristics of its metastases to the brain have been not well studied, unlike those of HER2 positive and triple negative subtypes. Aim: A  comparative analysis of characteristics of metastatic brain lesions in patients with luminal breast cancer. Materials and methods: The time from surgery for breast cancer to the first recurrence and to metastatic brain lesions (assessed by contrast-enhanced MRI imaging was measured in 41 patients with luminal subtype of breast cancer (median age, 49.5±9.6  years, depending on a  diameter of the primary tumor and numbers of involved axillary lymph nodes. Results: The time interval to occurrence of brain metastases in luminal subtype of breast cancer is not associated with the size of the tumor. If≥4  axillary lymph nodes are involved (N2–3, brain metastases are identified much earlier (p<0.05 than in patients with N0–1 (34.5±23.9 months and 62.7±50 months, respectively. Neither the size nor the involvement of axillary lymph nodes has any impact on the rates of metastatic lesion to the brain during the first recurrence. Conclusion: Brain metastases occur at a much shorter time in those patients of luminal subtype of breast cancer who have metastases in≥4  axillary lymph nodes. Brain metastases develop in 50% of patients with the first recurrence of the luminal subtype of breast cancer.

  1. Improving the luminance and luminous efficacy of miniature fluorescent lamps for liquid crystal display backlighting by using a double frequency drive

    Science.gov (United States)

    Shiga, T.; Mikoshiba, S.; Curzon, F. L.; Shinada, S.

    1998-09-01

    A new method of driving miniature fluorescent tubes for liquid crystal display backlighting, with diameters as small as 2 mm, has been devised with the objective of improving the luminance and luminous efficacies of such lamps. The driver voltage wave form consists of high frequency oscillations at the leading and trailing edges of conventional square-wave form voltage pulses of relatively low frequency. The wave form is produced simply by inserting coils between low frequency square-wave pulse generators and the lamp electrodes. A lamp driven in this way operates in a different discharge mode from the conventional glow discharge obtained in the absence of the coils. The twofold intensity increase of visible emission from the positive column region indicates that the vacuum ultraviolet emission increases, enhancing the excitation of the phosphor in the lamp. There is evidence that the luminous efficacy is also increased by a factor of 2 as a result of more efficient use of the input energy. The minimum voltage needed to maintain a discharge is reduced.

  2. Charge on luminous bodies resembling natural ball lightning produced via electrical arcs through lump silicon

    Science.gov (United States)

    Porter, Christina L.; Miley, Galen P.; Griffiths, David J.; Sánchez, Erik

    2014-12-01

    A phenomenon resembling natural ball lightning can be produced via electrical arcing through silicon. We use lump silicon instead of silicon wafers to achieve higher production rates and larger, longer-lived luminous balls than previously reported. The luminous balls consist of a silicon core surrounded by a porous network of loosely bound silicon dioxide nanoparticles. We find that the balls carry a small net charge on the order of 10-12 C and propose that the nanoparticles are electrostatically bound to the core due to this charge.

  3. Hyperspectral VNIR and photogrammetric data fusion approach for urban luminance map generation

    Directory of Open Access Journals (Sweden)

    L. Pipia

    2016-12-01

    Full Text Available This paper puts forward a methodology for the generation of high resolution luminance maps from simultaneous hyperspectral VNIR and photogrammetric imagery. The integration of hyperspectral radiance at ground level, properly weighted by the photopic-based coefficients, plus a sensor fusion strategy, provides for the first time a quantitative description of the luminous flux at high spatial resolution and with multi-angle geometry. Accordingly, this methodology allows following up any strategic policy aimed to improve urban illumination management and quantifying its effects in terms of energetic efficiency.

  4. Prognostic Significance of Progesterone Receptor–Positive Tumor Cells Within Immunohistochemically Defined Luminal A Breast Cancer

    Science.gov (United States)

    Prat, Aleix; Cheang, Maggie Chon U.; Martín, Miguel; Parker, Joel S.; Carrasco, Eva; Caballero, Rosalía; Tyldesley, Scott; Gelmon, Karen; Bernard, Philip S.; Nielsen, Torsten O.; Perou, Charles M.

    2013-01-01

    Purpose Current immunohistochemical (IHC)-based definitions of luminal A and B breast cancers are imperfect when compared with multigene expression-based assays. In this study, we sought to improve the IHC subtyping by examining the pathologic and gene expression characteristics of genomically defined luminal A and B subtypes. Patients and Methods Gene expression and pathologic features were collected from primary tumors across five independent cohorts: British Columbia Cancer Agency (BCCA) tamoxifen-treated only, Grupo Español de Investigación en Cáncer de Mama 9906 trial, BCCA no systemic treatment cohort, PAM50 microarray training data set, and a combined publicly available microarray data set. Optimal cutoffs of percentage of progesterone receptor (PR) –positive tumor cells to predict survival were derived and independently tested. Multivariable Cox models were used to test the prognostic significance. Results Clinicopathologic comparisons among luminal A and B subtypes consistently identified higher rates of PR positivity, human epidermal growth factor receptor 2 (HER2) negativity, and histologic grade 1 in luminal A tumors. Quantitative PR gene and protein expression were also found to be significantly higher in luminal A tumors. An empiric cutoff of more than 20% of PR-positive tumor cells was statistically chosen and proved significant for predicting survival differences within IHC-defined luminal A tumors independently of endocrine therapy administration. Finally, no additional prognostic value within hormonal receptor (HR) –positive/HER2-negative disease was observed with the use of the IHC4 score when intrinsic IHC-based subtypes were used that included the more than 20% PR-positive tumor cells and vice versa. Conclusion Semiquantitative IHC expression of PR adds prognostic value within the current IHC-based luminal A definition by improving the identification of good outcome breast cancers. The new proposed IHC-based definition of luminal A

  5. Bupropion and its photoreactive analog (±)-SADU-3-72 interact with luminal and non-luminal sites at human α4β2 nicotinic acetylcholine receptors.

    Science.gov (United States)

    Arias, Hugo R; Feuerbach, Dominik; Ortells, Marcelo O

    2016-11-01

    The interaction of (±)-bupropion [(±)-BP] with the human (h) α4β2 nicotinic acetylcholine receptor (AChR) was compared to that for its photoreactive analog (±)-2-(N-tert-butylamino)-3'-iodo-4'-azidopropiophenone [(±)-SADU-3-72]. Ca2+ influx results indicated that (±)-SADU-3-72 and (±)-BP inhibit hα4β2 AChRs with practically the same potency. However, (±)-SADU-3-72 binds to the [3H]imipramine sites at resting and desensitized hα4β2 AChRs with 3-fold higher affinity compared to that for (±)-BP, which is supported by molecular docking results. The docking results also indicate that each isomer of BP and SADU-3-72, in the protonated state, interacts with luminal and non-luminal sites. In the channel lumen, both ligands bind to two overlapping subsites, one that overlaps the imipramine site, and another much closer to the cytoplasmic side. The results suggest, for the first time, three differentiated non-luminal domains, including the transmembrane (TMD), extracellular (ECD), and ECD-TMD junction. In the ECD-TMD junction, BP and SADU-3-72 bind to overlapping sites. Interestingly, only SADU-3-72 binds to intrasubunit and intersubunit sites in the TMD, and to additional sites in the ECD. Our results are consistent with a model where BP and SADU-3-72 bind to overlapping sites in the luminal and ECD-TMD junctional domains of the hα4β2, whereas only SADU-3-72 binds to additional non-luminal sites. The BP junctional site opens the door for additional inhibitory mechanisms. The pharmacological properties of (±)-SADU-3-72 showed in this work support further photolabeling studies to mapping the BP binding sites in the hα4β2 AChR. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. A novel visual saliency detection method for infrared video sequences

    Science.gov (United States)

    Wang, Xin; Zhang, Yuzhen; Ning, Chen

    2017-12-01

    Infrared video applications such as target detection and recognition, moving target tracking, and so forth can benefit a lot from visual saliency detection, which is essentially a method to automatically localize the ;important; content in videos. In this paper, a novel visual saliency detection method for infrared video sequences is proposed. Specifically, for infrared video saliency detection, both the spatial saliency and temporal saliency are considered. For spatial saliency, we adopt a mutual consistency-guided spatial cues combination-based method to capture the regions with obvious luminance contrast and contour features. For temporal saliency, a multi-frame symmetric difference approach is proposed to discriminate salient moving regions of interest from background motions. Then, the spatial saliency and temporal saliency are combined to compute the spatiotemporal saliency using an adaptive fusion strategy. Besides, to highlight the spatiotemporal salient regions uniformly, a multi-scale fusion approach is embedded into the spatiotemporal saliency model. Finally, a Gestalt theory-inspired optimization algorithm is designed to further improve the reliability of the final saliency map. Experimental results demonstrate that our method outperforms many state-of-the-art saliency detection approaches for infrared videos under various backgrounds.

  7. The ER stress sensor PERK luminal domain functions as a molecular chaperone to interact with misfolded proteins

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng; Li, Jingzhi; Sha, Bingdong

    2016-11-29

    PERK is one of the major sensor proteins which can detect the protein-folding imbalance generated by endoplasmic reticulum (ER) stress. It remains unclear how the sensor protein PERK is activated by ER stress. It has been demonstrated that the PERK luminal domain can recognize and selectively interact with misfolded proteins but not native proteins. Moreover, the PERK luminal domain may function as a molecular chaperone to directly bind to and suppress the aggregation of a number of misfolded model proteins. The data strongly support the hypothesis that the PERK luminal domain can interact directly with misfolded proteins to induce ER stress signaling. To illustrate the mechanism by which the PERK luminal domain interacts with misfolded proteins, the crystal structure of the human PERK luminal domain was determined to 3.2 Å resolution. Two dimers of the PERK luminal domain constitute a tetramer in the asymmetric unit. Superimposition of the PERK luminal domain molecules indicated that the β-sandwich domain could adopt multiple conformations. It is hypothesized that the PERK luminal domain may utilize its flexible β-sandwich domain to recognize and interact with a broad range of misfolded proteins.

  8. 10 CFR 32.22 - Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license...

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Self-luminous products containing tritium, krypton-85 or... containing tritium, krypton-85 or promethium-147: Requirements for license to manufacture, process, produce... self-luminous products containing tritium, krypton-85, or promethium-147, or to initially transfer such...

  9. High luminous flux from single crystal phosphor-converted laser-based white lighting system

    KAUST Repository

    Cantore, Michael

    2015-12-14

    The efficiency droop of light emitting diodes (LEDs) with increasing current density limits the amount of light emitted per wafer area. Since low current densities are required for high efficiency operation, many LED die are needed for high power white light illumination systems. In contrast, the carrier density of laser diodes (LDs) clamps at threshold, so the efficiency of LDs does not droop above threshold and high efficiencies can be achieved at very high current densities. The use of a high power blue GaN-based LD coupled with a single crystal Ce-doped yttrium aluminum garnet (YAG:Ce) sample was investigated for white light illumination applications. Under CW operation, a single phosphor-converted LD (pc-LD) die produced a peak luminous efficacy of 86.7 lm/W at 1.4 A and 4.24 V and a peak luminous flux of 1100 lm at 3.0 A and 4.85 V with a luminous efficacy of 75.6 lm/W. Simulations of a pc-LD confirm that the single crystal YAG:Ce sample did not experience thermal quenching at peak LD operating efficiency. These results show that a single pc-LD die is capable of emitting enough luminous flux for use in a high power white light illumination system.

  10. Luminal volume reconstruction from angioscopic video images of casts from human coronary arteries

    NARCIS (Netherlands)

    J.C.H. Schuurbiers (Johan); C.J. Slager (Cornelis); P.W.J.C. Serruys (Patrick)

    1994-01-01

    textabstractIntravascular angioscopy has been hampered by its limitation in quantifying obtained images. To circumvent this problem, a lightwire was used, which projects a ring of light onto the endoluminal wall in front of the angioscope. This investigation was designed to quantify luminal

  11. Luminance gradient configuration determines perceived lightness in a simple geometric illusion

    Directory of Open Access Journals (Sweden)

    Maria ePereverzeva

    2014-12-01

    Full Text Available Accurate perception of surface reflectance poses a significant computational problem for the visual system. The amount of light reflected by a surface is affected by a combination of factors including the surface’s reflectance properties and illumination conditions. The latter are not limited by the strength of the illuminant but also include the relative placement of the light illuminating the surface, the orientation of the surface and its 3d shape, all of which result in a pattern of luminance gradients across the surface. In this study we explore how luminance gradients contribute to lightness perception. We introduce a novel, simple lightness illusion. It consists of six separate checks, organized in rows of two. Each check has a negative luminance gradient across it. The top and the bottom rows are the same: with the darker check on the left, and the lighter check on the right. Two checks in the middle row are identical; however, the check on the right appears darker than the check on the left. As there are no shared borders between the checks, simultaneous contrast cannot explain the effect. However, there are multiple possible explanations including spatial filtering (Blakeslee & McCourt, 2004 or some higher-order mechanism such as perceptual grouping or amodal completion. Here, we explore these possibilities by manipulating the luminance configurations and the gradient slopes of the checks.

  12. Luminance gradient configuration determines perceived lightness in a simple geometric illusion.

    Science.gov (United States)

    Pereverzeva, Maria; Murray, Scott O

    2014-01-01

    Accurate perception of surface reflectance poses a significant computational problem for the visual system. The amount of light reflected by a surface is affected by a combination of factors including the surface's reflectance properties and illumination conditions. The latter are not limited by the strength of the illuminant but also include the relative placement of the light illuminating the surface, the orientation of the surface and its 3d shape, all of which result in a pattern of luminance gradients across the surface. In this study we explore how luminance gradients contribute to lightness perception. We introduce a novel, simple lightness illusion. It consists of six separate checks, organized in rows of two. Each check has a negative luminance gradient across it. The top and the bottom rows are the same: with the darker check on the left, and the lighter check on the right. Two checks in the middle row are identical; however, the check on the right appears darker than the check on the left. As there are no shared borders between the checks, simultaneous contrast cannot explain the effect. However, there are multiple possible explanations including spatial filtering (Blakeslee and McCourt, 2004) or some higher-order mechanism such as perceptual grouping or amodal completion. Here, we explore these possibilities by manipulating the luminance configurations and the gradient slopes of the checks.

  13. Artemisia supplementation differentially affects the mucosal and luminal ileal microbiota of diet-induced obese mice.

    Science.gov (United States)

    Wicks, Shawna; Taylor, Christopher M; Luo, Meng; Blanchard, Eugene; Ribnicky, David M; Cefalu, William T; Mynatt, Randall L; Welsh, David A

    2014-01-01

    The gut microbiome has been implicated in obesity and metabolic syndrome; however, most studies have focused on fecal or colonic samples. Several species of Artemisia have been reported to ameliorate insulin signaling both in vitro and in vivo. The aim of this study was to characterize the mucosal and luminal bacterial populations in the terminal ileum with or without supplementation with Artemisia extracts. Following 4 wk of supplementation with different Artemisia extracts (PMI 5011, Santa or Scopa), diet-induced obese mice were sacrificed and luminal and mucosal samples of terminal ileum were used to evaluate microbial community composition by pyrosequencing of 16 S rDNA hypervariable regions. Significant differences in community structure and membership were observed between luminal and mucosal samples, irrespective of diet group. All Artemisia extracts increased the Bacteroidetes to Firmicutes ratio in mucosal samples. This effect was not observed in the luminal compartment. There was high interindividual variability in the phylogenetic assessments of the ileal microbiota, limiting the statistical power of this pilot investigation. Marked differences in bacterial communities exist depending on the biogeographic compartment in the terminal ileum. Future studies testing the effects of Artemisia or other botanical supplements require larger sample sizes for adequate statistical power. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Cloning and characterization of luciferase from a Fijian luminous click beetle.

    Science.gov (United States)

    Mitani, Yasuo; Futahashi, Ryo; Niwa, Kazuki; Ohba, Nobuyoshi; Ohmiya, Yoshihiro

    2013-01-01

    Luminous click beetle is distributed almost exclusively in Central and South America with a single genus in Melanesia. Among these click beetles, the description of Melanesian species has been fragmentary, and its luciferase gene and phylogenetic relation to other click beetles still remain uncertain. We collected a living luminous click beetle, Photophorus jansonii in Fiji. It emits green-yellow light from two spots on the pronotum and has no ventral luminous organ. Here, we cloned a luciferase gene from this insect by RT-PCR. The deduced amino acid sequence showed high identity of ~85% to the luciferases derived from other click beetle species. The luciferase of the Fijian click beetle was produced as a recombinant protein to characterize its biochemical properties. The Km for D-luciferin and ATP were 173 and 270 μm, respectively. The luciferase was pH-insensitive and the spectrum measured at pH 8.0 showed a peak at 559 nm, which was in the range of green-yellow light as seen in the luminous spot of the living Fijian click beetle. The Fijian click beetle luciferase was assigned to the Elateridae clade by a phylogenetic analysis, but it made a clearly different branch from Pyrophorus group examined in this study. © 2013 The American Society of Photobiology.

  15. Separation of luminance and chromatic information by Hebb-Stent rules

    Science.gov (United States)

    McIlhagga, William; Cole, Graeme

    1994-05-01

    The P cell pathway in primates is involved in both luminance and chromatic perception. This correlates well with P cell receptive fields, which are both spatially and chromatically opponent. Since, however, the luminance and chromatic channels found in psychophysics are independent, the mixed luminance and chromatic information in P cell signals must be demultiplexed in cortex. We have examined the ability of an unsupervised neural network to demultiplex P cell signals, using realistic visual inputs. Digitized images, corrected to be statically similar to retinal images, were sampled by a simulated retinal mosaic, and filtered by difference-of-Gaussians P cell receptive fields. The simulated P cell signals were used as inputs to a network designed to maximize unit responses while minimizing the correlation between units. After a period of training, we evaluated the receptive fields formed in the network. The neurons clearly fell into two categories. The first were those sensitive to changes in intensity in the retinal image; that is, luminance selective units. The second were those sensitive to a color difference in the retinal image; that is, chromatically selective units.

  16. Modulation of visual cortical excitability by working memory: effect of luminance contrast of mental imagery

    Directory of Open Access Journals (Sweden)

    Zaira eCattaneo

    2011-02-01

    Full Text Available Although much is known about the impact of stimulus properties such as luminance contrast, spatial frequency and orientation on visually evoked neural activity, much less is known about how they modulate neural activity when they are properties of a mental image held in working memory (WM. Here we addressed this question by investigating how a parametric manipulation of an imagined stimulus attribute affects neuronal excitability in the early visual cortex. We manipulated luminance contrast, a stimulus property known to strongly affect the magnitude of neuronal responses in early visual areas. Luminance contrast modulated neuronal excitability, as assessed by the frequency of phosphenes induced by transcranial magnetic stimulation (TMS with the exact nature of this modulation depending on TMS intensity. These results point to a strong overlap in the neuronal processes underlying visual perception and mental imagery: not only does WM maintenance selectively engage neurons which are tuned to the maintained attribute (as has previously been shown, but the extent to which those neurons are activated depends on the luminance contrast (as is the case with visually-evoked responses. From a methodological viewpoint, these results suggest that assessment of visual cortical excitability using TMS is affected by the TMS intensity used to probe the neuronal population.

  17. Distribution of luminous bacteria and bacterial luminescence in the equatorial region of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaiah, N.; Chandramohan, D.

    and 500 m, and a free living pattern in the surface samples. Vibrio fischeri contributed to more than 45% of the total luminous bacteria collected for the seawater samples, while, V. harveyi was the dominant species (53%) associated with the zooplankton...

  18. Luminance-color correlation is not used to estimate the color of the illumination

    NARCIS (Netherlands)

    Granzier, JJM; Brenner, E; Cornelissen, FW; Smeets, JBJ

    2005-01-01

    Humans can identify the colors of objects fairly consistently, despite considerable variations in the spectral composition of the illumination. It has been suggested that the correlation between luminance and color within a scene helps to disentangle the influences of illumination and reflectance,

  19. Luminal Cells Are Favored as the Cell of Origin for Prostate Cancer

    Directory of Open Access Journals (Sweden)

    Zhu A. Wang

    2014-09-01

    Full Text Available The identification of cell types of origin for cancer has important implications for tumor stratification and personalized treatment. For prostate cancer, the cell of origin has been intensively studied, but it has remained unclear whether basal or luminal epithelial cells, or both, represent cells of origin under physiological conditions in vivo. Here, we use a novel lineage-tracing strategy to assess the cell of origin in a diverse range of mouse models, including Nkx3.1+/−; Pten+/−, Pten+/−, Hi-Myc, and TRAMP mice, as well as a hormonal carcinogenesis model. Our results show that luminal cells are consistently the observed cell of origin for each model in situ; however, explanted basal cells from these mice can generate tumors in grafts. Consequently, we propose that luminal cells are favored as cells of origin in many contexts, whereas basal cells only give rise to tumors after differentiation into luminal cells.

  20. Spatial disturbances in altered mucosal and luminal gut viromes of diet-induced obese mice.

    Science.gov (United States)

    Kim, Min-Soo; Bae, Jin-Woo

    2016-05-01

    Gut microbial biogeography is a key feature of host-microbe relationships. In gut viral ecology, biogeography and responses to dietary intervention remain poorly understood. Here, we conducted a metagenomic study to determine the composition of the mucosal and luminal viromes of the gut and to evaluate the impact of a Western diet on gut viral ecology. We found that mucosal and luminal viral assemblages comprised predominantly temperate phages. The mucosal virome significantly differed from the luminal virome in low-fat diet-fed lean mice, where spatial variation correlated with bacterial microbiota from the mucosa and lumen. The mucosal and luminal viromes of high-fat, high-sucrose 'Western' diet-fed obese mice were significantly enriched with temperate phages of the Caudovirales order. Interestingly, this community alteration occurred to a greater extent in the mucosa than lumen, leading to loss of spatial differences; however, these changes recovered after switching to a low-fat diet. Temperate phages enriched in the Western diet-induced obese mice were associated with the Bacilli, Negativicutes and Bacteroidia classes and temperate phages from the Bacteroidia class particularly encoded stress and niche-specific functions advantageous to bacterial host adaptation. This study illustrates a biogeographic view of the gut virome and phage-bacterial host connections under the diet-induced microbial dysbiosis. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  1. Illumination Frame of Reference in the Object-Reviewing Paradigm: A Case of Luminance and Lightness

    Science.gov (United States)

    Fiedler, Anja; Moore, Cathleen M.

    2015-01-01

    The present study combines the object-reviewing paradigm (Kahneman, Treisman, & Gibbs, 1990) with the checkershadow illusion (Adelson, 1995) in order to contrast the effects of objects’ luminance versus lightness on the object-specific preview benefit. To this end, we manipulated objects’ luminance and the amount of illumination given by an informative background scene in four experiments. In line with previous studies (Moore, Stephens, & Hein, 2010), there was no object-specific preview benefit when objects were presented on a uniformly colored background and luminance switched between objects. In contrast, when objects were presented on the checkershadow illusion background which provided an explanation for the luminance switch, a reliable object-specific preview benefit was observed. This suggests that object correspondence as measured by the object-reviewing paradigm can be influenced by scene-induced, perceived lightness of objects’ surfaces. We replicated this finding and moreover showed that the scene context only influences the object-specific preview benefit if the objects are perceived as part of the background scene. PMID:26280265

  2. Undetectable changes in image resolution of luminance-contrast gradients affect depth perception.

    Directory of Open Access Journals (Sweden)

    Yoshiaki eTsushima

    2016-02-01

    Full Text Available A great number of studies have suggested a variety of ways to get depth information from two dimensional images such as binocular disparity, shape-from-shading, size gradient/ foreshortening, aerial perspective, and so on. Are there any other new factors affecting depth perception? A recent psychophysical study has investigated the correlation between image resolution and depth sensation of Cylinder images (A rectangle contains gradual luminance-contrast changes.. It was reported that higher resolution images facilitate depth perception. However, it is still not clear whether or not the finding generalizes to other kinds of visual stimuli, because there are more appropriate visual stimuli for exploration of depth perception of luminance-contrast changes, such as Gabor patch. Here, we further examined the relationship between image resolution and depth perception by conducting a series of psychophysical experiments with not only Cylinders but also Gabor patches having smoother luminance-contrast gradients. As a result, higher resolution images produced stronger depth sensation with both images. This finding suggests that image resolution affects depth perception of simple luminance-contrast differences (Gabor patch as well as shape-from-shading (Cylinder. In addition, this phenomenon was found even when the resolution difference was undetectable. This indicates the existence of consciously available and unavailable information in our visual system. These findings further support the view that image resolution is a cue for depth perception that was previously ignored. It partially explains the unparalleled viewing experience of novel high resolution displays.

  3. UVB-activated psoralen reduces luminal narrowing after balloon dilation because of inhibition of constrictive remodeling

    NARCIS (Netherlands)

    Perrée, Jop; van Leeuwen, Ton G.; Velema, Evelyn; Smeets, Mirjam; de Kleijn, Dominique; Borst, Cornelius

    2002-01-01

    In this study we have explored the potential of PUVB (8-MOP + UVB) therapy for the reduction of luminal narrowing after arterial injury. In 15 rabbits, balloon dilation of iliac arteries was performed. In 20 arteries, dilation was combined with the delivery of pulsed ultraviolet light B (UVB)

  4. Adaptive luminance contrast for enhancing reading performance and visual comfort on smartphone displays

    Science.gov (United States)

    Na, Nooree; Suk, Hyeon-Jeong

    2014-11-01

    This study developed a model for setting the adaptive luminance contrast between text and background for enhancing reading performance and visual comfort on smartphone displays. The study was carried out in two experiments. In Experiment I, a user test was conducted to identify the optimal luminance contrast with regard to subjects' reading performance, measured by lines of text reading and visual comfort, assessed by self-report after the reading. Based on the empirical results of the test, an ideal adaptive model which decreases the luminance contrast gradually with passage of time was developed. In Experiment II, a validation test involving reading performance, visual comfort, and physiological stress measured by a brainwave analysis using an electroencephalogram confirmed that the proposed adaptive luminance contrast is adequate for prolonged text reading on smartphone displays. The developed model enhances both reading performance and visual comfort as well as reduces the energy consumption of a smartphone; hence, it is expected that this study will be applied to diverse kinds of visual display terminals.

  5. Visual memory for random block patterns defined by luminance and color contrast

    NARCIS (Netherlands)

    Cornelissen, FW; Greenlee, MW

    2000-01-01

    We studied the ability of human subjects to memorize the visual information in computer-generated random block patterns defined either by luminance contrast, by color contrast, or by both. Memory performance declines rapidly with increasing inter-stimulus interval, showing a half-life of

  6. Luminance- and Texture-Defined Information Processing in School-Aged Children with Autism

    Science.gov (United States)

    Rivest, Jessica B.; Jemel, Boutheina; Bertone, Armando; McKerral, Michelle; Mottron, Laurent

    2013-01-01

    According to the complexity-specific hypothesis, the efficacy with which individuals with autism spectrum disorder (ASD) process visual information varies according to the extensiveness of the neural network required to process stimuli. Specifically, adults with ASD are less sensitive to texture-defined (or second-order) information, which necessitates the implication of several cortical visual areas. Conversely, the sensitivity to simple, luminance-defined (or first-order) information, which mainly relies on primary visual cortex (V1) activity, has been found to be either superior (static material) or intact (dynamic material) in ASD. It is currently unknown if these autistic perceptual alterations are present in childhood. In the present study, behavioural (threshold) and electrophysiological measures were obtained for static luminance- and texture-defined gratings presented to school-aged children with ASD and compared to those of typically developing children. Our behavioural and electrophysiological (P140) results indicate that luminance processing is likely unremarkable in autistic children. With respect to texture processing, there was no significant threshold difference between groups. However, unlike typical children, autistic children did not show reliable enhancements of brain activity (N230 and P340) in response to texture-defined gratings relative to luminance-defined gratings. This suggests reduced efficiency of neuro-integrative mechanisms operating at a perceptual level in autism. These results are in line with the idea that visual atypicalities mediated by intermediate-scale neural networks emerge before or during the school-age period in autism. PMID:24205355

  7. Luminance contrast has little influence on the spread of object-based attention

    NARCIS (Netherlands)

    Watson, P.; Korjoukov, I.; Vartak, D.; Roelfsema, P.R.

    2013-01-01

    We direct our attention to those visual stimuli that are relevant to our behavioral goals. Some of the visual stimuli that surround us are represented more strongly, because they have a higher luminance contrast. However, selective attention also boosts the representation of visual stimuli. It is

  8. Luminance contrast in the background makes flashes harder to detect during saccades.

    Science.gov (United States)

    Maij, Femke; Matziridi, Maria; Smeets, Jeroen B J; Brenner, Eli

    2012-05-01

    To explore a visual scene we make many fast eye movements (saccades) every second. During those saccades the image of the world shifts rapidly across our retina. These shifts are normally not detected, because perception is suppressed during saccades. In this paper we study the origin of this saccadic suppression by examining the influence of luminance borders in the background on the perception of flashes presented near the time of saccades in a normally illuminated room. We used different types of backgrounds: either with isoluminant red and green areas or with black and white areas. We found that the ability to perceive flashes that were presented during saccades was suppressed when there were luminance borders in the background, but not when there were isoluminant color borders in the background. Thus, masking by moving luminance borders plays an important role in saccadic suppression. The perceived positions of detected flashes were only influenced by the borders between the areas in the background when the flashes were presented before or after the saccades. Moreover, the influence did not depend on the kind of contrast forming the border. Thus, the masking effect of moving luminance borders does not appear to play an important role in the mislocalization of flashes that are presented near the time of saccades. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Electrical-thermal-luminous-chromatic model of phosphor-converted white light-emitting diodes

    NARCIS (Netherlands)

    Ye, H.; Koh, S.W.; Yuan, C.; Zeijl, H. van; Gielen, A.W.J.; Lee, S.W.R.; Zhang, G.

    2014-01-01

    The drive of increased electrical currents to achieve high luminous output for phosphor-converted white light-emitting diodes (PW-LED) has led to a series of thermal problems. The light performance of PW-LED is affected by the heat generated by the two major sources in a package/module: chip(s) and