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Sample records for lyman alpha mapping

  1. Lunar Reconnaissance Orbiter (LRO) Lyman Alpha Mapping Project (LAMP) Maps of the Permanently Shaded Regions (PSR) at the Lunar Poles

    Science.gov (United States)

    Rojas, Paul; Retherford, Kurt; Gladstone, Randall; Stern, Alan; Egan, Anthony; Miles, Paul; Parker, Joel; Kaufmann, David; Horvath, David; Greathouse, Thomas; Versteeg, Maartem; Steffl, Andrew; Mukherjee, Joey; Davis, Michael; Slater, David; Bayless, Amanda; Feldmann, Paul; Hurley, Dana; Pryor, Wayne; Hendrix, Amanda

    2013-04-01

    The Lyman Alpha Mapping Project (LAMP) instrument on-board LRO is a UV spectrograph covering the spectral range of 57-196 nm. We present Lyman-alpha and far-UV albedo maps of the north and south poles. These maps indicate that the coldest, permanently shadowed regions (PSR) in deep polar craters have significantly lower Lyman-alpha albedo than the surrounding regions, which is best explained by a high surface porosity there - possibly related to the accumulation of volatile frosts.

  2. Mapping High-Velocity H-alpha and Lyman-alpha Emission from Supernova 1987A

    Science.gov (United States)

    France, Kevin; McCray, Richard; Fransson, Claes; Larsson, Josefin; Frank, Kari A.; Burrows, David N.; Challis, Peter; Kirshner, Robert P.; Chevalier, Roger A.; Garnavich, Peter; Heng, Kevin; Lawrence, Stephen S.; Lundqvist, Peter; Smith, Nathan; Sonneborn, George

    2015-01-01

    We present new Hubble Space Telescope images of high-velocity H-alpha and Lyman-alpha emission in the outer debris of SN 1987A. The H-alpha images are dominated by emission from hydrogen atoms crossing the reverse shock. For the first time we observe emission from the reverse shock surface well above and below the equatorial ring, suggesting a bipolar or conical structure perpendicular to the ring plane. Using the H-alpha imaging, we measure the mass flux of hydrogen atoms crossing the reverse shock front, in the velocity intervals (-7,500 < V(sub obs) < -2,800 km/s) and (1,000 < V(sub obs) < 7,500 km/s), ?M(sub H) = 1.2 × 10(exp -3) M/ y. We also present the first Lyman-alpha imaging of the whole remnant and new Chandra X-ray observations. Comparing the spatial distribution of the Lyman-alpha and X-ray emission, we observe that the majority of the high-velocity Lyman-alpha emission originates interior to the equatorial ring. The observed Lyman-alpha/H-alpha photon ratio, R(L-alpha/H-alpha) approx. = 17, is significantly higher than the theoretically predicted ratio of approx. = 5 for neutral atoms crossing the reverse shock front. We attribute this excess to Lyman-alpha emission produced by X-ray heating of the outer debris. The spatial orientation of the Lyman-alpha and X-ray emission suggests that X-ray heating of the outer debris is the dominant Lyman-alpha production mechanism in SN 1987A at this phase in its evolution.

  3. Large-scale 3D mapping of the intergalactic medium using the Lyman Alpha Forest

    CERN Document Server

    Ozbek, Melih; Khandai, Nishikanta

    2016-01-01

    Maps of the large-scale structure of the Universe at redshifts 2-4 can be made with the Lyman-alpha forest which are complementary to low redshift galaxy surveys. We apply the Wiener interpolation method of Caucci et al. to construct three-dimensional maps from sets of Lyman-alpha forest spectra taken from cosmological hydrodynamic simulations. We mimic some current and future quasar redshift surveys (BOSS, eBOSS and MS-DESI) by choosing similar sightline densities. We use these appropriate subsets of the Lyman-alpha absorption sightlines to reconstruct the full three dimensional Lyman-alpha flux field and perform comparisons between the true and the reconstructed fields. We study global statistical properties of the intergalactic medium (IGM) maps with auto-correlation and cross-correlation analysis, slice plots, local peaks and point by point scatter. We find that both the density field and the statistical proper- ties of the IGM are recovered well enough that the resulting IGM maps can be meaningfully cons...

  4. Lyman Alpha Control

    CERN Document Server

    Nielsen, Daniel Stefaniak

    2015-01-01

    This document gives an overview of how to operate the Lyman Alpha Control application written in LabVIEW along with things to watch out for. Overview of the LabVIEW code itself as well as the physical wiring of and connections from/to the NI PCI-6229 DAQ box is also included. The Lyman Alpha Control application is the interface between the ALPHA sequencer and the HighFinesse Wavelength Meter as well as the Lyman Alpha laser setup. The application measures the wavelength of the output light from the Lyman Alpha cavity through the Wavelength Meter. The application can use the Wavelength Meter’s PID capabilities to stabilize the Lyman Alpha laser output as well as switch between up to three frequencies.

  5. Mapping High-velocity H-alpha and Lyman-alpha Emission from Supernova 1987A

    OpenAIRE

    France, Kevin; McCray, Richard; Fransson, Claes; Larsson, Josefin; Frank, Kari A.; Burrows, David N.; Challis, Peter; Kirshner, Robert P.; Chevalier, Roger A.; Garnavich, Peter; Heng, Kevin; Lawrence, Stephen S.; Lundqvist, Peter; Smith, Nathan; Sonneborn, George

    2015-01-01

    We present new {\\it Hubble Space Telescope} images of high-velocity H-$\\alpha$ and Lyman-$\\alpha$ emission in the outer debris of SN~1987A. The H-$\\alpha$ images are dominated by emission from hydrogen atoms crossing the reverse shock. For the first time we observe emission from the reverse shock surface well above and below the equatorial ring, suggesting a bipolar or conical structure perpendicular to the ring plane. Using the H$\\alpha$ imaging, we measure the mass flux of hydrogen atoms cr...

  6. LRO-Lyman Alpha Mapping Project (LAMP) Observations of the GRAIL Impact Plumes

    Science.gov (United States)

    Retherford, Kurt D.; Greathouse, T. K.; Hurley, D. M.; Gladstone, G. R.; Hayne, P. O.; Paige, D. A.; Greenhagen, B. T.; Sefton-Nash, E.; Zuber, M. T.; Smith, D. E.; Colaprete, A.; Kaufmann, D. E.; Miles, P. F.; Grava, C.; Throop, H.; Feldman, P. D.; Hendrix, A. R.; Pryor, W. R.; Stubbs, T. J.; Glenar, D. A.; Parker, J. W.; Stern, S. A.

    2013-10-01

    The Lyman Alpha Mapping Project (LAMP) UV spectrograph on the Lunar Reconnaissance Orbiter (LRO) was positioned to directly view the expanding gas plumes from the two GRAIL spacecraft impacts on 17 December 2012. LAMP detected resonantly scattered emissions from Hg and H atoms in the sunlit regions of these plumes. The spectral, spatial, and light-curve analyses used in these gas detections are consistent with previous LAMP observations of the LCROSS impact into the permanently shadowed region of Cabeus crater. LAMP's detection of atomic H by Lyman-α emission at the Moon (a first) was facilitated by pointing at the nightside surface to eliminate sky background noise. Volatile transport of Hg and H species is known to concentrate them near the poles, and in the context of LRO-Diviner temperature measurements of these high-latitude (75.6° N) impact sites the LAMP detections address this process.

  7. The Lyman alpha reference sample

    DEFF Research Database (Denmark)

    Hayes, M.; Östlin, G.; Schaerer, D.

    2013-01-01

    We report on new imaging observations of the Lyman alpha emission line (Lyα), performed with the Hubble Space Telescope, that comprise the backbone of the Lyman alpha Reference Sample. We present images of 14 starburst galaxies at redshifts 0.028 Lyman alpha emission line (Lyα), performed with the Hubble Space Telescope, that comprise the backbone of the Lyman alpha Reference Sample. We present images of 14 starburst galaxies at redshifts 0.028

  8. Nonparametric 3D map of the IGM using the Lyman-alpha forest

    CERN Document Server

    Cisewski, Jessi; Freeman, Peter E; Genovese, Christopher R; Khandai, Nishikanta; Ozbek, Melih; Wasserman, Larry

    2014-01-01

    Visualizing the high-redshift Universe is difficult due to the dearth of available data; however, the Lyman-alpha forest provides a means to map the intergalactic medium at redshifts not accessible to large galaxy surveys. Large-scale structure surveys, such as the Baryon Oscillation Spectroscopic Survey (BOSS), have collected quasar (QSO) spectra that enable the reconstruction of HI density fluctuations. The data fall on a collection of lines defined by the lines-of-sight (LOS) of the QSO, and a major issue with producing a 3D reconstruction is determining how to model the regions between the LOS. We present a method that produces a 3D map of this relatively uncharted portion of the Universe by employing local polynomial smoothing, a nonparametric methodology. The performance of the method is analyzed on simulated data that mimics the varying number of LOS expected in real data, and then is applied to a sample region selected from BOSS. Evaluation of the reconstruction is assessed by considering various feat...

  9. Simulating the Lyman Alpha Forest

    CERN Document Server

    Machacek, M E; Anninos, P; Meiksin, A; Norman, M L; Machacek, Marie E.; Bryan, Greg L.; Anninos, Peter; Meiksin, Avery; Norman, Michael L.

    1998-01-01

    In this paper we review the importance of the Lyman alpha forest as a probe of structure formation in the universe. We first discuss the statistics used to describe the Lyman alpha forest and the numerical techniques used to produce simulated spectra of the forest from a given cosmological model. We then discuss the physical picture of the absorbing structures that emerges from these numerical simulations. Finally, we comment on how two of the statistics, the slope of the column density distribution and the b parameter distribution, may be used to constrain competing cosmologies.

  10. What Powers Lyman alpha Blobs?

    CERN Document Server

    Ao, Y; Beelen, A; Henkel, C; Cen, R; De Breuck, C; Francis, P; Kovacs, A; Lagache, G; Lehnert, M; Mao, M; Menten, K M; Norris, R; Omont, A; Tatemastu, K; Weiss, A; Zheng, Z

    2015-01-01

    Lyman alpha blobs (LABs) are spatially extended lyman alpha nebulae seen at high redshift. The origin of Lyman alpha emission in the LABs is still unclear and under debate. To study their heating mechanism(s), we present Australia Telescope Compact Array (ATCA) observations of the 20 cm radio emission and Herschel PACS and SPIRE measurements of the far-infrared (FIR) emission towards the four LABs in the protocluster J2143-4423 at z=2.38. Among the four LABs, B6 and B7 are detected in the radio with fluxes of 67+/-17 microJy and 77+/-16 microJy, respectively, and B5 is marginally detected at 3 sigma (51+/-16 microJy). For all detected sources, their radio positions are consistent with the central positions of the LABs. B6 and B7 are obviously also detected in the FIR. By fitting the data with different templates, we obtained redshifts of 2.20$^{+0.30}_{-0.35}$ for B6 and 2.20$^{+0.45}_{-0.30}$ for B7 which are consistent with the redshift of the lyman alpha emission within uncertainties, indicating that both ...

  11. The cross-correlation between 21cm intensity mapping maps and the Lyman-alpha forest in the post-reionization era

    CERN Document Server

    Carucci, Isabella P; Viel, Matteo

    2016-01-01

    We investigate the cross-correlation signal between 21cm intensity mapping maps and the Lyman-alpha forest in the fully non-linear regime using state-of-the-art hydrodynamic simulations. The cross-correlation signal between these fields can provide a coherent and comprehensive picture of the neutral hydrogen (HI) content of our Universe in the post-reionization era, probing both its mass content and volume distribution. We compute the auto-power spectra of both fields together with their cross-power spectrum at z = 2.4 and find that on large scales the fields are completely anti-correlated. This anti-correlation arises because regions with high (low) 21cm emission, such as those with a large (low) concentration of damped Lyman-alpha systems, will show up as regions with low (high) transmitted flux. We find that on scales smaller than k = 0.2 h/Mpc the cross-correlation coefficient departs from -1, at a scale where non-linearities show up. We use the anisotropy of the power spectra in redshift-space to determi...

  12. Lyman Alpha Spicule Observatory (LASO)

    Science.gov (United States)

    Chamberlin, P. C.; Allred, J. C.; Airapetian, V.; Gong, Q.; Mcintosh, S. W.; De Pontieu, B.; Fontenla, J. M.

    2011-12-01

    The Lyman Alpha Spicule Observatory (LASO) sounding rocket will observe small-scale eruptive events called "Rapid Blue-shifted Events" (RBEs) [Rouppe van der Voort et al., 2009], the on-disk equivalent of Type-II spicules, and extend observations that explore their role in the solar coronal heating problem [De Pontieu et al., 2011]. LASO utilizes a new and novel optical design to simultaneously observe two spatial dimensions at 4.2" spatial resolution (2.1" pixels) over a 2'x2' field of view with high spectral resolution of 66mÅ (33mÅ pixels) across a broad 20Å spectral window. This spectral window contains three strong chromospheric and transition region emissions and is centered on the strong Hydrogen Lyman-α emission at 1216Å. This instrument makes it possible to obtain new data crucial to the physical understanding of these phenomena and their role in the overall energy and momentum balance from the upper chromosphere to lower corona. LASO was submitted March 2011 in response to the ROSES SHP-LCAS call.

  13. Lyman-alpha emission in star-forming galaxies

    Science.gov (United States)

    Hartmann, Lee W.; Huchra, John P.; Geller, Margaret J.; O'Brien, Paul; Wilson, Robert

    1988-01-01

    IUE observations of five blue, low-metallicity, star-forming galaxies sufficiently redshifted to permit detection of Lyman-alpha are reported. The galaxies with metallicities 0.1 time solar or more have weak or absent Lyman-alpha emission. There is evidence for increasing Lyman-alpha emission with decreasing metallicity. The reduction of Lyman-alpha fluxes from recombination values is attributed to absorption of multiply scattered Lyman-alpha by dust.

  14. Relativistic effects in Lyman-alpha forest

    CERN Document Server

    Iršič, Vid; Viel, Matteo

    2015-01-01

    We present the calculation of the Lyman-alpha (Lyman-$\\alpha$) transmitted flux fluctuations with full relativistic corrections to the first order. Even though several studies exist on relativistic effects in galaxy clustering, this is the first study to extend the formalism to a different tracer of underlying matter at unique redshift range ($z = 2 - 5$). Furthermore, we show a comprehensive application of our calculations to the Quasar- Lyman-$\\alpha$ cross-correlation function. Our results indicate that the signal of relativistic effects can be as large as 30% at Baryonic Acoustic Oscillation (BAO) scale, which is much larger than anticipated and mainly due to the large differences in density bias factors of our tracers. We construct an observable, the anti-symmetric part of the cross- correlation function, that is dominated by the relativistic signal and offers a new way to measure the relativistic terms at relatively small scales. The analysis shows that relativistic effects are important when considerin...

  15. First stars in Damped Lyman Alpha systems

    NARCIS (Netherlands)

    Salvadori, Stefania; Ferrara, Andrea

    2011-01-01

    In order to characterize Damped Lyman Alpha systems (DLAs) potentially host- ing first stars, we present a novel approach to investigate DLAs in the context of Milky Way (MW) formation, along with their connection with the most metal-poor stars and local dwarf galaxies. The merger tree method previo

  16. First stars in Damped Lyman Alpha systems

    NARCIS (Netherlands)

    Salvadori, Stefania; Ferrara, Andrea

    In order to characterize Damped Lyman Alpha systems (DLAs) potentially host- ing first stars, we present a novel approach to investigate DLAs in the context of Milky Way (MW) formation, along with their connection with the most metal-poor stars and local dwarf galaxies. The merger tree method

  17. Lyman-alpha Forest Tomography from Background Galaxies: The First Megaparsec-Resolution Large-Scale Structure Map at z>2

    CERN Document Server

    Lee, Khee-Gan; Stark, Casey; Prochaska, J Xavier; White, Martin; Schlegel, David J; Eilers, Anna-Christina; Arinyo-i-Prats, Andreu; Suzuki, Nao; Croft, Rupert A C; Caputi, Karina I; Cassata, Paolo; Ilbert, Olivier; Garilli, Bianca; Koekemoer, Anton M; Brun, Vincent Le; Fèvre, Olivier Le; Maccagni, Dario; Nugent, Peter; Taniguchi, Yoshiaki; Tasca, Lidia A M; Tresse, Laurence; Zamorani, Gianni; Zucca, Elena

    2014-01-01

    We present the first observations of foreground Lyman-$\\alpha$ forest absorption from high-redshift galaxies, targeting 24 star-forming galaxies (SFGs) with $z\\sim 2.3-2.8$ within a $5' \\times 15'$ region of the COSMOS field. The transverse sightline separation is $\\sim 2\\,h^{-1}\\mathrm{Mpc}$ comoving, allowing us to create a tomographic reconstruction of the 3D Ly$\\alpha$ forest absorption field over the redshift range $2.20\\leq z\\leq 2.45$. The resulting map covers $6\\,h^{-1}\\mathrm{Mpc} \\times 14\\,h^{-1}\\mathrm{Mpc}$ in the transverse plane and $230\\,h^{-1}\\mathrm{Mpc}$ along the line-of-sight with a spatial resolution of $\\approx 3.5\\,h^{-1}\\mathrm{Mpc}$, and is the first high-fidelity map of large-scale structure on $\\sim\\mathrm{Mpc}$ scales at $z>2$. Our map reveals significant structures with $\\gtrsim 10\\,h^{-1}\\mathrm{Mpc}$ extent, including several spanning the entire transverse breadth, providing qualitative evidence for the filamentary structures predicted to exist in the high-redshift cosmic web. ...

  18. Modeling the Lyman-alpha Forest in Collisionless Simulations

    CERN Document Server

    Sorini, Daniele; Lukić, Zarija; Hennawi, Joseph F

    2016-01-01

    Cosmological hydrodynamic simulations can accurately predict the properties of the intergalactic medium (IGM), but only under the condition of retaining high spatial resolution necessary to resolve density fluctuations in the IGM. This resolution constraint prohibits simulating large volumes, such as those probed by BOSS and future surveys, like DESI and 4MOST. To overcome this limitation, we present Iteratively Matched Statistics (IMS), a novel method to accurately model the Lyman-alpha forest with collisionless N-body simulations, where the relevant density fluctuations are unresolved. We use a small-box, high-resolution hydrodynamic simulation to obtain the probability distribution function (PDF) and the power spectrum of the real-space Lyman-alpha forest flux. These two statistics are iteratively mapped onto a pseudo-flux field of an N-body simulation, which we construct from the matter density. We demonstrate that our method can perfectly reproduce line-of-sight observables, such as the PDF and power spe...

  19. Lyman-alpha observations of astrospheres

    CERN Document Server

    Linsky, Jeffrey L

    2014-01-01

    Charge-exchange reactions between outflowing stellar wind protons and interstellar neutral hydrogen atoms entering a stellar astrosphere produce a region of piled-up-decelerated neutral hydrogen called the hydrogen wall. Absorption by this gas, which is observed in stellar Lyman-alpha emission lines, provides the only viable technique at this time for measuring the mass-loss rates of F-M dwarf stars. We describe this technique, present an alternative way for understanding the relation of mass-loss rate with X-ray emission, and identify several critical issues.

  20. The visibility of Lyman Alpha Emitters during reionization

    CERN Document Server

    Dayal, Pratika; Ferrara, Andrea

    2010-01-01

    We present the first Lyman Alpha Emitter (LAE) study that combines: (i) cosmological SPH simulations run using GADGET-2, (ii) radiative transfer simulations (CRASH), and (iii) a previously developed LAE model. This complete LAE model accounts for the intrinsic LAE Lyman Alpha/continuum luminosity, dust enrichment and Lyman Alpha transmission through the intergalactic medium (IGM), to quantify the effects of reionization, dust and velocity fields on the Lyman Alpha and UV Luminosity Functions (LF). We find that a model neglecting dust sorely fails to reproduce either the slope or the magnitude of the observed Lyman Alpha and UV LFs. Clumped dust is required to simultaneously fit the observed UV and Lyman Alpha LFs, such that the intrinsic Lyman Alpha-to-continuum luminosity is enhanced by a factor f_alpha/f_c ~ 1.5 (3.7) excluding (including) peculiar velocities. The higher value including velocity fields arises since LAEs reside in large potential wells and inflows decrease their Lyman Alpha transmission. For...

  1. Lyman alpha SMM/UVSP absolute calibration and geocoronal correction

    Science.gov (United States)

    Fontenla, Juan M.; Reichmann, Edwin J.

    1987-01-01

    Lyman alpha observations from the Ultraviolet Spectrometer Polarimeter (UVSP) instrument of the Solar Maximum Mission (SMM) spacecraft were analyzed and provide instrumental calibration details. Specific values of the instrument quantum efficiency, Lyman alpha absolute intensity, and correction for geocoronal absorption are presented.

  2. GHRS Observations of the Lyman $\\alpha$ Forest

    CERN Document Server

    Morris, S L

    1996-01-01

    I review the results obtained using the GHRS on low redshift Lyman alpha absorbers. Until the advent of HST and the GHRS, the existence of such absorbers was doubted. The confirmation of their existence, in one of the first GHRS GTO team results to be published, must rank as one of the HSTs most interesting results. The GHRS resolution allows us to probe equivalent widths well below those detectable with the FOS, and has led to a number of interesting new questions. One example is the apparent disagreement between the GHRS result that there are many Lyman alpha absorbers which are not associated with luminous galaxies, and FOS studies which suggest that all such absorbers have a nearby galaxy causing them. This almost certainly shows that the equivalent width (or column density) range reachable by the GHRS includes gas from a wide range of causes, and not only the halos of luminous galaxies. With these data, we are seeing the debris left over from Galaxy formation, material flung out from galaxy interactions ...

  3. Characterizing Lyman Alpha Scattering in Nearby Galaxies

    Science.gov (United States)

    Bridge, Joanna; Hayes, Matthew; Melinder, Jens; Östlin, Göran; Gronwall, Caryl

    2017-01-01

    The hydrogen emission line of Lyman alpha (Lyα) has long been recognized as key to studying high redshift star-forming galaxies. However, due to the resonance of the emission line, the path that a Lyα photon takes from emission to eventual escape from the galaxy is essentially a mystery. This scattering poses a problem for using Lyα as a key emission feature of galaxies because it results in Lyα not being observed in all star-forming galaxies, and, in galaxies where it is observed, the place where the photon is originally emitted and where it is observed are two very different things. We discuss here how the Lyman-Alpha Reference Sample (LARS) provides a unique sample of 14 nearby (0.02 Space Telescope imaging. We compare the Lyα/Hα ratios with those expected from pure dust attenuation models, finding that in some cases significant positive departures are found on small scales, consistent with geometrical effects being important on sizes comparable to the HII regions. We then develop a simple scattering model in which we are able to estimate the average path length a Lyα photon travels with respect to non-resonant radiation, and quantifiy the excess dust optical depth to which Lyα radiation may be susceptible.

  4. Molecular hydrogen in Lyman Alpha Emitters

    CERN Document Server

    Vallini, Livia; Ferrara, Andrea

    2012-01-01

    We present a physically motivated model to estimate the molecular hydrogen (H2) content of high-redshift (z~5.7,6.6) Lyman Alpha Emitters (LAEs) extracted from a suite of cosmological simulations. We find that the H2 mass fraction, (f_H2), depends on three main LAE physical properties: (a) star formation rate, (b) dust mass, and (c) cold neutral gas mass. At z~5.7, the value of f_H2 peaks and ranges between 0.5-0.9 for intermediate mass LAEs with stellar mass M_* ~ 10^{9-10} solar mass, decreasing for both smaller and larger galaxies. However, the largest value of the H2 mass is found in the most luminous LAEs. These trends also hold at z\\sim6.6, although, due to a lower dust content, f_H2(z=6.6)\\sim0.5 f_H2(z=5.7) when averaged over all LAEs; they arise due to the interplay between the H2 formation/shielding controlled by dust and the intensity of the ultraviolet (UV) Lyman-Werner photo-dissociating radiation produced by stars. We then predict the carbon monoxide (CO) luminosities for such LAEs and check tha...

  5. Giant Lyman-Alpha Nebulae in the Illustris Simulation

    CERN Document Server

    Gronke, Max

    2016-01-01

    Several `giant' Lyman-$\\alpha$ (Ly$\\alpha$) nebulae with extent $\\gtrsim 300\\,$kpc and observed Ly$\\alpha$ luminosity of $\\gtrsim 10^{44}\\,{\\rm erg}\\,{\\rm s}^{-1}\\,{\\rm cm}^{-2}\\,{\\rm arcsec}^{-2}$ have recently been detected, and it has been speculated that their presence hints at a substantial cold gas reservoir in small cool clumps not resolved in modern hydro-dynamical simulations. We use the Illustris simulation to predict the Ly$\\alpha$ emission emerging from large halos ($M > 10^{11.5}M_{\\odot}$) at $z\\sim 2$ and thus test this model. We consider both AGN and star driven ionization, and compared the simulated surface brightness maps, profiles and Ly$\\alpha$ spectra to a model where most gas is clumped below the simulation resolution scale. We find that while the cold clumps boost the Ly$\\alpha$ luminosity especially in the outer regions of the halo -- as expected by previous work -- with Illustris no additional clumping is necessary to explain the extents and luminosities of the `giant Ly$\\alpha$ nebul...

  6. On the Diffuse Lyman-alpha Halo Around Lyman-alpha Emitting Galaxies

    CERN Document Server

    Lake, Ethan; Cen, Renyue; Sadoun, Raphael; Momose, Rieko; Ouchi, Masami

    2015-01-01

    Ly$\\alpha$ photons scattered by neutral hydrogen atoms in the circumgalactic media or produced in the halos of star-forming galaxies are expected to lead to extended Ly$\\alpha$ emission around galaxies. Such low surface brightness Ly$\\alpha$ halos (LAHs) have been detected by stacking Ly$\\alpha$ images of high-redshift star-forming galaxies. We study the origin of LAHs by performing radiative transfer modeling of nine $z=3.1$ Lyman-Alpha Emitters (LAEs) in a high resolution hydrodynamic galaxy formation simulation. We develop a method of computing the mean Ly$\\alpha$ surface brightness profile of each LAE by effectively integrating over many different observing directions. Without adjusting any parameters, our model yields an average Ly$\\alpha$ surface brightness profile in remarkable agreement with observations. We find that observed LAHs can not be accounted for solely by photons originating from the central LAE and scattered to large radii by hydrogen atoms in the circumgalactic gas. Instead, Ly$\\alpha$ em...

  7. Geocoronal Lyman Alpha Observations with COS

    Science.gov (United States)

    Ake, Thomas B.

    2012-01-01

    The time-tagged mode of the Cosmic Origins Spectrograph (COS) provides a convenient method of studying the orbital variation of geocoronal Lyman-alpha emission at the altitude of HST. We have analyzed G130M blank sky exposures from scheduled STIS parallels and observations for which the target acquisition failed. We supplement these with observations of WD standard stars from flat field and sensitivity monitoring programs where the stellar Lyα profile can be modeled and its contribution to the geocoronal emission removed. Data were corrected for time-dependent sensitivity changes and gain sag. The measurements have been fit by an analytical model based on the orbital position of HST and the angle between the target and the Earth as seen from HST. The Lyα emission varies from less than 2 kR for a target observed at orbit midnight to 37 kR for one observed at the bright Earth limb at orbit noon. A long-term trend of increasing flux is evident, consistent with solar Lyα measurements by SOLSTICE on SORCE as the next solar maximum is approached. We expect the irradiance at solar maximum to be at least 50-55 kR. This level still should not trigger local count rate violations for the FUV detector, but will accelerate gain sag of the microchannel plates in the regions where Lyα falls.

  8. Isolating the Lyman Alpha Forest BAO Anomaly

    CERN Document Server

    Evslin, Jarah

    2016-01-01

    A 2.5-3 sigma discrepancy has been reported between the baryonic acoustic oscillation peak (BAO) in the Lyman alpha forest at z=2.34 and the best fit Planck LCDM cosmology. To isolate the origin of the tension, we consider unanchored BAO, in which the standard BAO ruler is not calibrated, eliminating any dependence on cosmology before redshift z=2.34. We consider BOSS BAO measurements at z=0.32, 0.57 and 2.34, using the full 2-dimensional constraints on the best and worst determined combinations of the angular and line of sight BAO scale, as well as isotropic BAO measurements by 6dF and SDSS at z=0.106 and z=0.15. We find that the z>0.43 data alone is in 2.8 sigma of tension with LCDM with or without the Planck best fit values of the mass fraction and the BAO scale, indicating that the tension arises not from the LCDM parameters but from the dark energy evolution itself at 0.57

  9. The Lyman alpha reference sample. VII. Spatially resolved Hα kinematics

    Science.gov (United States)

    Herenz, Edmund Christian; Gruyters, Pieter; Orlitova, Ivana; Hayes, Matthew; Östlin, Göran; Cannon, John M.; Roth, Martin M.; Bik, Arjan; Pardy, Stephen; Otí-Floranes, Héctor; Mas-Hesse, J. Miguel; Adamo, Angela; Atek, Hakim; Duval, Florent; Guaita, Lucia; Kunth, Daniel; Laursen, Peter; Melinder, Jens; Puschnig, Johannes; Rivera-Thorsen, Thøger E.; Schaerer, Daniel; Verhamme, Anne

    2016-03-01

    We present integral field spectroscopic observations with the Potsdam Multi-Aperture Spectrophotometer of all 14 galaxies in the z ~ 0.1 Lyman Alpha Reference Sample (LARS). We produce 2D line-of-sight velocity maps and velocity dispersion maps from the Balmer α (Hα) emission in our data cubes. These maps trace the spectral and spatial properties of the LARS galaxies' intrinsic Lyα radiation field. We show our kinematic maps that are spatially registered onto the Hubble Space Telescope Hα and Lyman α (Lyα) images. We can conjecture a causal connection between spatially resolved Hα kinematics and Lyα photometry for individual galaxies, however, no general trend can be established for the whole sample. Furthermore, we compute the intrinsic velocity dispersion σ0, the shearing velocity vshear, and the vshear/σ0 ratio from our kinematic maps. In general LARS galaxies are characterised by high intrinsic velocity dispersions (54 km s-1 median) and low shearing velocities (65 km s-1 median). The vshear/σ0 values range from 0.5 to 3.2 with an average of 1.5. It is noteworthy that five galaxies of the sample are dispersion-dominated systems with vshear/σ0 1. Our result indicates that turbulence in actively star-forming systems is causally connected to interstellar medium conditions that favour an escape of Lyα radiation. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).The reduced data cubes (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A78

  10. Lyman-alpha Emission From Cosmic Structure I: Fluorescence

    CERN Document Server

    Kollmeier, Juna A; Davé, Romeel; Gould, Andrew; Katz, Neal; Miralda-Escudé, Jordi; Weinberg, David H

    2009-01-01

    We present predictions for the fluorescent Lyman-alpha emission signature arising from photoionized, optically thick structures in Smoothed Particle Hydrodynamic (SPH) cosmological simulations of a Lambda-CDM universe using a Monte Carlo Lyman-alpha radiative transfer code. We calculate the expected Lyman-alpha image and 2-dimensional spectra for gas exposed to a uniform ultraviolet ionizing background as well as gas exposed additionally to the photoionizing radiation from a local quasar, after correcting for the self-shielding of hydrogen. As a test of our numerical methods and for application to current observations, we examine simplified analytic structures that are uniformly or anisotropically illuminated. We compare these results with recent observations. We discuss future observing campaigns on large telescopes and realistic strategies for detecting fluorescence owing to the ambient metagalactic ionization and in regions close to bright quasars. While it will take hundreds of hours on the current genera...

  11. Low-redshift evolution of the Lyman $\\alpha$ Forest

    CERN Document Server

    Theuns, T; Efstathiou, G P

    1998-01-01

    The low-redshift evolution of the intergalactic medium is investigated using hydrodynamic cosmological simulations. The assumed cosmological model is a critical density cold dark matter universe. The imposed uniform background of ionizing radiation has the amplitude, shape and redshift evolution as computed from the observed quasar luminosity function by Haardt & Madau. We have analysed simulated Lyman-alpha spectra using Voigt-profile fitting, mimicking the procedure with which quasar spectra are analysed. Our simulations reproduce the observed evolution of the number of Lyman-alpha absorption lines over the whole observed interval of z=0.5 to z=4. In particular, our simulations show that the decrease in the rate of evolution of Lyman-alpha absorption lines at z< 2, as observed by Hubble Space Telescope, can be explained by the steep decline in the photo-ionizing background resulting from the rapid decline in quasar numbers at low redshift.

  12. Fluctuations in the High-Redshift Lyman-Werner and Lyman-alpha Radiation Backgrounds

    CERN Document Server

    Holzbauer, Lauren N

    2011-01-01

    We use a new method to model fluctuations of the Lyman-Werner (LW) and Lyman-alpha radiation backgrounds at high redshift. At these early epochs the backgrounds are symptoms of a universe newly lit with its first stars. LW photons (11.5-13.6 eV) are of particular interest because they dissociate molecular hydrogen, the primary coolant in the first minihalos. By using a variation of the halo model, we efficiently generate power spectra for any choice of radiation background. We find that the LW power spectrum typically traces the matter power spectrum at large scales but turns over at the scale corresponding to the effective `horizon' of LW photons (~100 comoving Mpc), unless the sources are extremely rare. The series of horizons that characterize the Lyman-alpha flux profile shape the fluctuations of that background in a similar fashion, though those imprints are washed out once one considers fluctuations in the brightness temperature of the 21-cm signal. The Lyman-alpha background strongly affects the redshi...

  13. Enhanced direct collapse due to Lyman {\\alpha} feedback

    CERN Document Server

    Johnson, Jarrett L

    2016-01-01

    We assess the impact of trapped Lyman {\\alpha} cooling radiation on the formation of direct collapse black holes (DCBHs). We apply a one-zone chemical and thermal evolution model, accounting for the photodetachment of H$^-$ ions, precursors to the key coolant H$_{\\rm 2}$, by Lyman {\\alpha} photons produced during the collapse of a cloud of primordial gas in an atomic cooling halo at high redshift. We find that photodetachment of H$^-$ by trapped Lyman {\\alpha} photons can lower the level of the H$_{\\rm 2}$-dissociating background radiation field required for DCBH formation substantially, dropping the critical flux by up to an order of magnitude. This translates into a large increase in the expected number density of DCBHs in the early Universe, and implies that DCBHs may be the seeds for the BHs residing in the centers of a significant fraction of galaxies today. We find that detachment of H$^-$ by Lyman {\\alpha} has the strongest impact on the critical flux for the relatively high background radiation temper...

  14. Broadband distortion modeling in Lyman-$\\alpha$ forest BAO fitting

    CERN Document Server

    Blomqvist, Michael; Bautista, Julian E; Ariño, Andreu; Busca, Nicolás G; Miralda-Escudé, Jordi; Slosar, Anže; Font-Ribera, Andreu; Margala, Daniel; Schneider, Donald P; Vazquez, Jose A

    2015-01-01

    In recent years, the Lyman-$\\alpha$ absorption observed in the spectra of high-redshift quasars has been used as a tracer of large-scale structure by means of the three-dimensional Lyman-$\\alpha$ forest auto-correlation function at redshift $z\\simeq 2.3$, but the need to fit the quasar continuum in every absorption spectrum introduces a broadband distortion that is difficult to correct and causes a systematic error for measuring any broadband properties. We describe a $k$-space model for this broadband distortion based on a multiplicative correction to the power spectrum of the transmitted flux fraction that suppresses power on scales corresponding to the typical length of a Lyman-$\\alpha$ forest spectrum. Implementing the distortion model in fits for the baryon acoustic oscillation (BAO) peak position in the Lyman-$\\alpha$ forest auto-correlation, we find that the fitting method recovers the input values of the linear bias parameter $b_{F}$ and the redshift-space distortion parameter $\\beta_{F}$ for mock dat...

  15. Exploring 21CM - Lyman Alpha Emitter Synergies for SKA

    NARCIS (Netherlands)

    Dayal, Pratika; Hutter, Anne; Müller, Volker; Trott, C. M.

    2017-01-01

    We study the signatures of reionization and ionizing properties of the early galaxies in the cross-correlations between the 21cm emission from the spin-flip transition of neutral hydrogen (H I ) and the underlying galaxy population, in particular a sub-population of galaxies visible as Lyman Alpha E

  16. Lyman-alpha spectral properties of five newly discovered Lyman continuum emitters

    CERN Document Server

    Verhamme, A; Schaerer, D; Izotov, Y; Worseck, G; Thuan, T X; Guseva, N

    2016-01-01

    We have recently reported the discovery of five low redshift Lyman continuum (LyC) emitters (LCEs, hereafter) with absolute escape fractions fesc(LyC) ranging from 6 to 13%, higher than previously found, and which more than doubles the number of low redshift LCEs.We use these observations to test theoretical predictions about a link between the characteristics of the Lyman-alpha (Lya) line from galaxies and the escape of ionising photons. We analyse the Lya spectra of eight LCEs of the local Universe observed with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope (our five leakers and three galaxies from the litterature), and compare their strengths and shapes to the theoretical criteria and comparison samples of local galaxies: the Lyman Alpha Reference Survey, Lyman Break Analogs, Green Peas, and the high-redshift strong LyC leaker Ion2. Our LCEs are found to be strong Lya emitters, with high equivalent widths, EW(Lya)> 70 {\\AA}, and large Lya escape fractions, fesc(Lya) > 20%. The Lya prof...

  17. Lyman alpha emission in starbursts: implications for galaxies at high redshift

    CERN Document Server

    Mas-Hesse, J M; Tenorio-Tagle, G; Leitherer, C; Terlevich, R J; Terlevich, E

    2003-01-01

    We present the results of a high resolution UV 2-D spectroscopic survey of star forming galaxies observed with HST-STIS. Our main aim was to map the Lyman alpha profiles to learn about the gas kinematics and its relation with the escape of Lyman alpha photons and to detect extended Lyman alpha emission due to scattering in gaseous halos. We have combined our data with previously obtained UV spectroscopy on other three star-forming galaxies. We find that the P-Cygni profile is spatially extended, smooth and spans several kiloparsecs covering a region much larger than the starburst itself. We propose a scenario whereby an expanding super-shell is generated by the interaction of the combined stellar winds and supernova ejecta from the young starbursts, with an extended low density halo. The variety of observed Lyman alpha profiles both in our sample and in high redshift starbursts is explained as phases in the time evolution of the super-shell expanding into the disk and halo of the host galaxy. The observed sha...

  18. New interpretations of extraterrestrial Lyman-alpha observations.

    Science.gov (United States)

    Blum, P. W.; Fahr, H. J.

    1972-01-01

    The solar Lyman-alpha radiation pressure affects the orbits and the velocities of the interstellar particles entering the solar system. This leads to enhanced particle losses in the heliosphere, since particles spend a longer time crossing it. This causes a stronger decrease of the density with decreasing distances from the sun than had been calculated without accounting for the radiation pressure. Furthermore, the emission pattern of the solar Lyman-alpha radiation is anisotropic and rotates with the sun in a 27-day period. This causes a temporal change in the location of the intensity extrema. At the same time it produces hydrogen density anisotropies with extrema deviating in their directions from those which had been calculated without consideration of the radiation pressure.

  19. The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

    Science.gov (United States)

    Ishikawa, Shin-nosuke; Kano, R.; Kobayashi, K.; Bando, T.; Narukage, N..; Ishikawa, R.; Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Hara, H.; hide

    2014-01-01

    To Understand energy release process in the Sun including solar flares, it is essentially important to measure the magnetic field of the atmosphere of the Sun. Magnetic field measurement of the upper layers (upper chromosphere and above) was technically difficult and not well investigated yet. Upper chromosphere and transition region magnetic field measurement by Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) sounding rocket to be launched in 2015. The proposal is already selected and developments of the flight components are going.

  20. Lyman alpha emission in starburst galaxies

    Science.gov (United States)

    Kunth, Daniel

    1999-07-01

    We propose to perform a deep study of Ly-alpha emission and destruction in 3 star-forming galaxies. These objects have been already observed with the GHRS and exhibit a variety of situations, with Ly-alpha showing P Cyg profiles, secondary emissions or even a deep damped absorption line with no emission. They also span a range of intrinsic properties: IZW18 is a gas-rich, metal deficient dust free dwarf galaxy, Haro 2 has a simple morphology while IRAS 08339+6517 is a luminous IRAS starburst galaxy with more dust and complex Ly- alpha profile. The use of STIS will allow for the first time to study the geometrical/kinematical configuration of the ionized and neutral gas across the galaxies nuclear regions and pin point the effects of porosity and the kinematical structure of the ISM, that may play the key roles {in addition to dust} in the detectability of the line. This study will have important impact for cosmology since Ly-alpha emitters are nowaday found at high-re dshift. We strongly emphasize that since Ly-alpha is primarely a diagnostic of the ISM, a full understanding of how the ISM and Ly-alpha are related is a necessary step before we can hope to correlate Ly-alpha to the cosmic star-formation rate. Our results will be interpreted against the model of superbubble evolution developed with G. Tenorio Tagle.

  1. A connection between extremely strong Damped Lyman-alpha Systems and Lyman-alpha Emitting Galaxies at small impact parameters

    CERN Document Server

    Noterdaeme, P; Paris, I; Cai, Z; Finley, H; Ge, J; Pieri, M M; York, D G

    2014-01-01

    We present a study of ~100 high redshift (z~2-4) extremely strong damped Lyman-alpha systems (ESDLA, with N(HI)>0.5x10^22 cm^-2) detected in quasar spectra from the Baryon Oscillation Spectroscopic Survey SDSS-III DR11. We study the neutral hydrogen, metal, and dust content of this elusive population of absorbers and confirm our previous finding that the high column density end of the N(HI) frequency distribution has a relatively shallow slope with power-law index -3.6, similar to what is seen from 21-cm maps in nearby galaxies. The stacked absorption spectrum indicates a typical metallicity ~1/20th solar, similar to the mean metallicity of the overall DLA population. The relatively small velocity extent of the low-ionisation lines suggests that ESDLAs do not arise from large-scale flows of neutral gas. The high column densities involved are in turn more similar to what is seen in DLAs associated with gamma-ray burst afterglows (GRB-DLAs), which are known to occur close to star forming regions. This indicates...

  2. Hydrogen Lyman-alpha and Lyman-beta radiances and profiles in polar coronal holes

    CERN Document Server

    Tian, Hui; Curdt, Werner; Vial, Jean-Claude

    2009-01-01

    The hydrogen Lyman-alpha plays a dominant role in the radiative energy transport in the lower transition region, and is important for the stud- ies of transition-region structure as well as solar wind origin. We investigate the Ly-alpha profiles obtained by SUMER in coronal holes and quiet Sun. In a subset of these observations, also the Hi Lyman-beta, Si iii, and O vi lines were (quasi-) simultaneously recorded. We find that the distances between the two peaks of Ly-alpha profiles are larger in coronal holes than in the quiet Sun, indicating a larger opacity in coronal holes. This difference might result from the different magnetic structures or the different radiation fields in the two regions. Most of the Ly-beta profiles in the coronal hole have a stronger blue peak, in contrast to those in quiet-Sun regions. Whilst in both regions the Ly-alpha profiles are stronger in the blue peak. Although the asymmetries are likely to be produced by differential flows in the solar atmosphere, their detailed formation ...

  3. The Lyman-$\\alpha$ signature of the first galaxies

    CERN Document Server

    Smith, Aaron; Bromm, Volker; Milosavljević, Miloš

    2014-01-01

    We present the Cosmic Lyman-$\\alpha$ Transfer code (COLT), a new massively parallel Monte-Carlo radiative transfer code, to simulate Lyman-$\\alpha$ (Ly$\\alpha$) resonant scattering through neutral hydrogen as a probe of the first galaxies. We explore the interaction of centrally produced Ly$\\alpha$ radiation with the host galactic environment. The Ly$\\alpha$ photons emitted from the luminous starburst region escape with characteristic features in the line profile depending on the density distribution, ionization structure, and bulk velocity fields. For example, the presence of anisotropic ionization exhibits a tall peak close to line centre with a skewed tail that drops off gradually. Furthermore, moderate (~10 km/s) outflow produces an amplified peak redward of line centre. Idealized models of first galaxies explore the effect of mass, anisotropic H II regions, and radiation pressure driven winds on Ly$\\alpha$ observables. We employ mesh refinement to resolve critical structures. We also post-process an ab i...

  4. Lyman-alpha Absorption from Heliosheath Neutrals

    CERN Document Server

    Wood, B E; Linsky, J L; Malama, Y G; Wood, Brian E.; Izmodenov, Vladislav V.; Linsky, Jeffrey L.; Malama, Yury G.

    2006-01-01

    We assess what information HST observations of stellar Ly-alpha lines can provide on the heliosheath, the region of the heliosphere between the termination shock and heliopause. To search for evidence of heliosheath absorption, we conduct a systematic inspection of stellar Ly-alpha lines reconstructed after correcting for ISM absorption (and heliospheric/astrospheric absorption, if present). Most of the stellar lines are well centered on the stellar radial velocity, as expected, but the three lines of sight with the most downwind orientations relative to the ISM flow (Chi1 Ori, HD 28205, and HD 28568) have significantly blueshifted Ly-alpha lines. Since it is in downwind directions where heliosheath absorption should be strongest, the blueshifts are almost certainly caused by previously undetected heliosheath absorption. We make an initial comparison between the heliosheath absorption and the predictions of a pair of heliospheric models. A model with a complex multi-component treatment of plasma within the he...

  5. NICMOS Snapshot Survey of Damped Lyman Alpha Quasars

    CERN Document Server

    Colbert, J W; Colbert, James W.; Malkan, Matthew A.

    2001-01-01

    We image 19 quasars with 22 damped Lyman alpha (DLA) systems using the F160W filter and the Near-Infrared Camera and Multiobject Spectrograph aboard the Hubble Space Telescope, in both direct and coronagraphic modes. We reach 5 sigma detection limits of ~H=22 in the majority of our images. We compare our observations to the observed Lyman-break population of high-redshift galaxies, as well as Bruzual & Charlot evolutionary models of present-day galaxies redshifted to the distances of the absorption systems. We predict H magnitudes for our DLAs, assuming they are producing stars like an L* Lyman-break galaxy (LBG) at their redshift. Comparing these predictions to our sensitivity, we find that we should be able to detect a galaxy around 0.5-1.0 L* (LBG) for most of our observations. We find only one new possible candidate, that near LBQS0010-0012. This scarcity of candidates leads us to the conclusion that most DLA systems are not drawn from a normal LBG luminosity function nor a local galaxy luminosity fun...

  6. Search for a direction in the forest of Lyman-$\\alpha$

    CERN Document Server

    Hazra, Dhiraj Kumar

    2015-01-01

    We report the first test of isotropy of the Universe in the matter dominated epoch using the Lyman-$\\alpha$ forest data from the high redshift quasars ($z>2$) from SDSS-III BOSS-DR9 datasets. Using some specified data cuts, we obtain the probability distribution function (PDF) of the Lyman-$\\alpha$ forest transmitted flux and use the statistical moments of the PDF to address the isotropy of the Universe. In an isotropic Universe one would expect the transmitted flux to have consistent statistical characteristics in different parts of the sky. We trisect the total survey area of 3275 ${\\rm deg}^2$ along the galactic latitude and using quadrant convention. We also make three subdivisions in the data for three different signal-to-noise-ratios (SNR). Finally we obtain and compare the statistical moments in the mean redshifts of 2.3, 2.6 and 2.9. We find, that the moments from all patches agree at all redshifts and at all SNRs, within 3$\\sigma$ uncertainties. Since Lyman-$\\alpha$ transmitted flux directly maps the...

  7. The Lyman Alpha Reference Sample: V. The impact of neutral ISM kinematics and geometry on Lyman Alpha escape

    CERN Document Server

    Rivera-Thorsen, Thøger E; Östlin, Göran; Duval, Florent; Orlitová, Ivana; Verhamme, Anne; Mas-Hesse, J Miguel; Schaerer, Daniel; Cannon, John M; Otí-Floranes, Héctor; Sandberg, Andreas; Guaita, Lucia; Adamo, Angela; Atek, Hakim; Herentz, E Christian; Kunth, Daniel; Laursen, Peter; Melinder, Jens

    2015-01-01

    We present high-resolution far-UV spectroscopy of the 14 galaxies of the Lyman Alpha Reference Sample; a sample of strongly star-forming galaxies at low redshifts ($0.028 < z < 0.18$). We compare the derived properties to global properties derived from multi band imaging and 21 cm HI interferometry and single dish observations, as well as archival optical SDSS spectra. Besides the Lyman $\\alpha$ line, the spectra contain a number of metal absorption features allowing us to probe the kinematics of the neutral ISM and evaluate the optical depth and and covering fraction of the neutral medium as a function of line-of-sight velocity. Furthermore, we show how this, in combination with precise determination of systemic velocity and good Ly$\\alpha$ spectra, can be used to distinguish a model in which separate clumps together fully cover the background source, from the "picket fence" model named by Heckman et al. (2011). We find that no one single effect dominates in governing Ly$\\alpha$ radiative transfer and ...

  8. Statistical Properties of Diffuse Lyman-alpha Halos around Star-forming Galaxies at z~2

    CERN Document Server

    Momose, Rieko; Nakajima, Kimihiko; Ono, Yoshiaki; Shibuya, Takatoshi; Shimasaku, Kazuhiro; Yuma, Suraphong; Mori, Masao; Umemura, Masayuki

    2015-01-01

    We present statistical properties of diffuse Lyman-alpha halos (LAHs) around high-$z$ star-forming galaxies with large Subaru samples of Lyman-alpha emitters (LAEs) at $z=2.2$. We make subsamples defined by the physical quantities of LAEs' central Lyman-alpha luminosities, UV magnitudes, Lyman-alpha equivalent widths, and UV slopes, and investigate LAHs' radial surface brightness (SB) profiles and scale lengths $r_n$ as a function of these physical quantities. We find that there exist prominent LAHs around LAEs with faint Lyman-alpha luminosities, bright UV luminosities, and small Lyman-alpha equivalent widths in cumulative radial Lyman-alpha SB profiles. We confirm this trend with the anti-correlation between $r_n$ and Lyman-alpha luminosities (equivalent widths) based on the Spearman's rank correlation coefficient that is $\\rho=-0.9$ ($-0.7$) corresponding to the $96\\%$ ($93\\%$) confidence level, although the correlation between $r_n$ and UV magnitudes is not clearly found in the rank correlation coefficien...

  9. Lyman alpha emission from the first galaxies : Implications of UV backgrounds and the formation of molecules

    NARCIS (Netherlands)

    Latif, M. A.; Schleicher, D. R. G.; Spaans, Maarten; Zaroubi, S.

    2011-01-01

    The Lyman alpha line is a robust tracer of high redshift galaxies. We present estimates of Lyman alpha emission from a protogalactic halo illuminated by UV background radiation fields with various intensities. For this purpose, we performed cosmological hydrodynamics simulations with the adaptive me

  10. Lyman alpha emission from the first galaxies : Implications of UV backgrounds and the formation of molecules

    NARCIS (Netherlands)

    Latif, M. A.; Schleicher, D. R. G.; Spaans, Maarten; Zaroubi, S.

    The Lyman alpha line is a robust tracer of high redshift galaxies. We present estimates of Lyman alpha emission from a protogalactic halo illuminated by UV background radiation fields with various intensities. For this purpose, we performed cosmological hydrodynamics simulations with the adaptive

  11. Lyman-alpha Forests cool Warm Dark Matter

    CERN Document Server

    Baur, Julien; Yèche, Christophe; Magneville, Christophe; Viel, Matteo

    2015-01-01

    The free-streaming of keV-scale particles impacts structure growth on scales that are probed by the Lyman-alpha forest of distant quasars. Using an unprecedentedly large sample of medium-resolution QSO spectra from the ninth data release of SDSS, along with a state-of-the-art set of hydrodynamical simulations to model the Lyman-alpha forest in the non-linear regime, we issue the tightest bounds to date on pure dark matter particles: $m_X \\gtrsim 4.35 \\: \\rm{keV}$ (95% CL) for early decoupled thermal relics such as a hypothetical gravitino, and its corresponding bound for a non-resonantly produced right-handed neutrino $m_s \\gtrsim 31.7 \\: \\rm{keV}$ (95% CL). Thanks to SDSS-III data featuring smaller uncertainties and covering a larger redshift range than SDSS-I data, our bounds improve upon those established by previous works and are further at odds with a purely non-resonantly produced sterile neutrino as dark matter.

  12. Lyman-alpha Forest Constraints on Decaying Dark Matter

    CERN Document Server

    Wang, Mei-Yu; Peter, Annika H G; Zentner, Andrew R; Purcell, Chris W

    2013-01-01

    We present an analysis of high-resolution N-body simulations of decaying dark matter cosmologies focusing on the statistical properties of the transmitted Lyman-alpha forest flux in the high-redshift intergalactic medium. In this type of model a dark matter particle decays into a slightly less massive stable dark matter daughter particle and a comparably light particle. The small mass splitting provides a non-relativistic kick velocity V_k to the daughter particle resulting in free-streaming and subsequent damping of small-scale density fluctuations. Current Lyman-alpha forest power spectrum measurements probe comoving scales up to ~ 2-3 h^-1 Mpc at redshifts z ~ 2-4, providing one of the most robust ways to probe cosmological density fluctuations on relatively small scales. The suppression of structure growth due to the free-streaming of dark matter daughter particles also has a significant impact on the neutral hydrogen cloud distribution, which traces the underlying dark matter distribution well at high re...

  13. Lyman-alpha radiation hydrodynamics of galactic winds before cosmic reionization

    Science.gov (United States)

    Smith, Aaron; Bromm, Volker; Loeb, Abraham

    2017-01-01

    Radiation from the first stars and galaxies initiated the dramatic phase transition marking an end to the cosmic dark ages. The emission and absorption signatures from the Lyman-alpha transition of neutral hydrogen have been indispensable in extending the observational frontier for high-redshift galaxies into the epoch of reionization. Lyman-alpha radiative transfer provides clues about the processes leading to Lyman-alpha escape from individual galaxies and the subsequent transmission through the intergalactic medium. Cosmological simulations incorporating Lyman-alpha radiative transfer enhance our understanding of fundamental physics by supplying the inferred spectra and feedback on the gas. We discuss the dynamical impact of Lyman-alpha radiation pressure on galaxy formation throughout cosmic reionization with the first fully coupled Lyman-alpha radiation-hydrodynamics simulations. We self-consistently follow the chemistry, cooling, self-gravity, and ionizing radiation in protogalaxies and find that Lyman-alpha radiation pressure turns out to be dynamically important in several spherically symmetric simulations. As a case in point we apply our model to the COSMOS redshift 7 (CR7) galaxy at z = 6.6, which exhibits a +160 km/s velocity offset between the Lyman-alpha and HeII line peaks. We find that a massive black hole with a nonthermal Compton-thick spectrum is able to reproduce the observed Lyman-alpha signatures as a result of higher photon trapping and longer potential lifetime. We conclude with a general discussion of Lyman-alpha radiation in the first galaxies by considering simulations that cover the expected range of halo and source properties.

  14. The Dynamical Masses, Densities, and Star Formation Scaling Relations of Lyman Alpha Galaxies

    CERN Document Server

    Rhoads, James E; Finkelstein, Steven L; Fynbo, Johan P U; McLinden, Emily M; Richardson, Mark L A; Tilvi, Vithal S

    2013-01-01

    We present the first dynamical mass measurements for Lyman alpha galaxies at high redshift, based on velocity dispersion measurements from rest-frame optical emission lines and size measurements from HST imaging, for a sample of nine galaxies drawn from four surveys. These measurements enable us to study the nature of Lyman alpha galaxies in the context of galaxy scaling relations. The resulting dynamical masses range from 1e9 to 1e10 solar masses. We also fit stellar population models to our sample, and use them to plot the Lyman alpha sample on a stellar mass vs. line width relation. Overall, the Lyman alpha galaxies follow well the scaling relation established by observing star forming galaxies at lower redshift (and without regard for Lyman alpha emission), though in 1/3 of the Lyman alpha galaxies, lower-mass fits are also acceptable. In all cases, the dynamical masses agree with established stellarmass-linewidth relation. Using the dynamical masses as an upper limit on gas mass, we show that Lyman alpha...

  15. Hubble Space Telescope Imaging of Lyman Alpha Emission at z=4.4

    CERN Document Server

    Finkelstein, Steven L; Windhorst, Rogier A; Ryan, Russell E; Hathi, Nimish P; Finkelstein, Keely D; Anderson, Jay; Grogin, Norman A; Koekemoer, Anton M; Malhotra, Sangeeta; Mutchler, Max; Rhoads, James E; McCarthy, Patrick J; O'Connell, Robert W; Balick, Bruce; Bond, Howard E; Calzetti, Daniela; Disney, Michael J; Dopita, Michael A; Frogel, Jay A; Hall, Donald N B; Holtzman, Jon A; Kimble, Randy A; Luppino, Gerard; Paresce, Francesco; Saha, Abhijit; Silk, Joseph I; Trauger, John T; Walker, Alistair R; Whitmore, Bradley C; Young, Erick T

    2010-01-01

    We present the highest redshift detections of resolved Lyman alpha emission, using Hubble Space Telescope/ACS F658N narrowband-imaging data taken in parallel with the Wide Field Camera 3 Early Release Science program in the GOODS CDF-S. We detect Lyman alpha emission from three spectroscopically confirmed z = 4.4 Lyman alpha emitting galaxies (LAEs), more than doubling the sample of LAEs with resolved Lyman alpha emission. Comparing the light distribution between the rest-frame ultraviolet continuum and narrowband images, we investigate the escape of Lyman alpha photons at high redshift. While our data do not support a positional offset between the Lyman alpha and rest-frame ultraviolet (UV) continuum emission, the half-light radii in two out of the three galaxies are significantly larger in Lyman alpha than in the rest-frame UV continuum. This result is confirmed when comparing object sizes in a stack of all objects in both bands. Additionally, the narrowband flux detected with HST is significantly less than...

  16. Hydrodynamical Simulations of the Lyman $\\alpha$ Forest Model Comparisons

    CERN Document Server

    Machacek, M E; Meiksin, A; Anninos, P; Thayer, D; Norman, M L; Zhang, Y

    1999-01-01

    We investigate the properties of the Lyman alpha forest as predicted by numerical simulations for a range of currently viable cosmological models. This is done in order to understand the dependencies of the forest on cosmological parameters. Focusing on the redshift range from two to four, we show that: (1) most of the evolution in the distributions of optical depth, flux and column density can be understood by simple scaling relations, (2) the shape of optical depth distribution is a sensitive probe of the amplitude of density fluctuations on scales of a few hundred kpc, (3) the mean of the b distribution (a measure of the width of the absorption lines) is also very sensitive to fluctuations on these scales, and decreases as they increase. We perform a preliminary comparison to observations, where available. A number of other properties are also examined, including the evolution in the number of lines, the two-point flux distribution and the HeII opacity.

  17. Reproducing the Kinematics of Damped Lyman-alpha Systems

    CERN Document Server

    Bird, Simeon; Neeleman, Marcel; Genel, Shy; Vogelsberger, Mark; Hernquist, Lars

    2014-01-01

    We examine the kinematic structure of Damped Lyman-alpha Systems (DLAs) in a series of cosmological hydrodynamic simulations using the AREPO code. We are able to match the distribution of velocity widths of associated low ionisation metal absorbers substantially better than earlier work. Our simulations produce a population of DLAs dominated by halos with virial velocities around 70 km/s, consistent with a picture of relatively small, faint objects. In addition, we reproduce the observed correlation between velocity width and metallicity and the equivalent width distribution of SiII. Some discrepancies of moderate statistical significance remain; too many of our spectra show absorption concentrated at the edge of the profile and there are slight differences in the exact shape of the velocity width distribution. We show that the improvement over previous work is mostly due to our strong feedback from star formation and our detailed modelling of the metal ionisation state.

  18. Detecting Damped Lyman-$\\alpha$ Absorbers with Gaussian Processes

    CERN Document Server

    Garnett, Roman; Bird, Simeon; Schneider, Jeff

    2016-01-01

    We develop an automated technique for detecting damped Lyman-$\\alpha$ absorbers (DLAs) along spectroscopic sightlines to quasi-stellar objects (QSOs or quasars). The detection of DLAs in large-scale spectroscopic surveys such as SDSS-III sheds light on galaxy formation at high redshift, showing the nucleation of galaxies from diffuse gas. We use nearly 50 000 QSO spectra to learn a novel tailored Gaussian process model for quasar emission spectra, which we apply to the DLA detection problem via Bayesian model selection. We propose models for identifying an arbitrary number of DLAs along a given line of sight. We demonstrate our method's effectiveness using a large-scale validation experiment, with excellent performance. We also provide a catalog of our results applied to 162 861 spectra from SDSS-III data release 12.

  19. Sample variance and Lyman-alpha forest transmission statistics

    CERN Document Server

    Rollinde, Emmanuel; Schaye, Joop; Pâris, Isabelle; Petitjean, Patrick

    2012-01-01

    We compare the observed probability distribution function of the transmission in the \\HI\\ Lyman-alpha forest, measured from the UVES 'Large Programme' sample at redshifts z=[2,2.5,3], to results from the GIMIC cosmological simulations. Our measured values for the mean transmission and its PDF are in good agreement with published results. Errors on statistics measured from high-resolution data are typically estimated using bootstrap or jack-knife resampling techniques after splitting the spectra into chunks. We demonstrate that these methods tend to underestimate the sample variance unless the chunk size is much larger than is commonly the case. We therefore estimate the sample variance from the simulations. We conclude that observed and simulated transmission statistics are in good agreement, in particular, we do not require the temperature-density relation to be 'inverted'.

  20. An excess of damped Lyman alpha galaxies near QSOs

    CERN Document Server

    Russell, D M; Ellison, S L; Benn, Chris R.; Ellison, Sara L.; Russell, David M.

    2006-01-01

    We present a sample of 33 damped Lyman alpha systems (DLAs) discovered in the Sloan Digital Sky Survey (SDSS) whose absorption redshifts (z_abs) are within 6000 km/s of the QSO's systemic redshift (z_sys). Our sample is based on 731 2.5 = 2e20 cm^-2. The derived number density of DLAs per unit redshift, n(z), within v < 6000 km/s is higher (3.5 sigma significance) by almost a factor of 2 than that of intervening absorbers observed in the SDSS DR3, i.e. there is evidence for an overdensity of galaxies near the QSOs. This provides a physical motivation for excluding DLAs at small velocity separations in surveys of intervening 'field' DLAs. In addition, we find that the overdensity of proximate DLAs is independent of the radio-loudness of the QSO, consistent with the environments of radio-loud and radio-quiet QSOs being similar.

  1. Baryon Acoustic Oscillations in the Lyman Alpha Forest

    CERN Document Server

    Norman, Michael L; Harkness, Robert

    2009-01-01

    We use hydrodynamic cosmological simulations in a (600 Mpc)^3 volume to study the observability of baryon acoustic oscillations (BAO) in the intergalactic medium as probed by Lyman alpha forest (LAF) absorption. The large scale separation between the wavelength of the BAO mode (~150 Mpc) and the size of LAF absorbers (~100 kpc) makes this a numerically challenging problem. We report on several 2048^3 simulations of the LAF using the ENZO code. We adopt WMAP5 concordance cosmological parameters and power spectrum including BAO perturbations. 5000 synthetic HI absorption line spectra are generated randomly piercing the box face. We calculate the cross-correlation function between widely separated pairs. We detect the BAO signal at z=3 where theory predicts to moderate statistical significance.

  2. Minimally Parametric Constraints on the Primordial Power Spectrum from Lyman-alpha

    CERN Document Server

    Bird, Simeon

    2010-01-01

    Current analyses of the Lyman-alpha forest assume that the primordial power spectrum of density perturbations obeys a simple power law, a strong theoretical assumption which should be tested. Employing a large suite of numerical simulations which drop this assumption, we reconstruct the shape of the primordial power spectrum using Lyman-alpha data from the Sloan Digital Sky Survey (SDSS). Our method combines a minimally parametric framework with cross-validation, a technique used to avoid over-fitting the data. Future work will involve predictions for the upcoming Baryon Oscillation Sky Survey (BOSS), which will provide new Lyman-alpha data with vastly decreased statistical errors.

  3. Copernicus measurement of the Jovian Lyman-alpha emission and its aeronomical significance

    Science.gov (United States)

    Atreya, S. K.; Kerr, R. B.; Upson, W. L., II; Festou, M. C.; Donahue, T. M.; Barker, E. S.; Cochran, W. D.; Bertaux, J. L.

    1982-01-01

    It is pointed out that the intensity of the Lyman-alpha emission is a good indicator of the principal aeronomical processes on the major planets. The high-resolution ultraviolet spectrometer aboard the Orbiting Astronomical Observatory Copernicus was used in 1980 April and May to detect the Jovian Lyman-alpha emission by spectroscopically discriminating it from other Doppler shifted Lyman-alpha emissions such as those of the geocorona, and the interplanetary medium. Taking into consideration the reported emission data, it appears that an unusually large energy input due to the particle precipitation in the auroral region must have been responsible for the large observed Lyman-alpha intensity during the Voyager encounter. At most other times, the observed Jovian Lyman-alpha intensity can be explained, within the range of statistical uncertainty, by a model that takes into consideration the solar EUV flux, the solar Lyman-alpha flux, the high exospheric temperature, and the eddy diffusion coefficient without energy input from the auroral sources.

  4. Spatially Resolved Emission of a z~3 Damped Lyman Alpha Galaxy with Keck/OSIRIS IFU

    Science.gov (United States)

    Christenson, Holly; Jorgenson, Regina

    2017-01-01

    The damped Lyman alpha (DLA) class of galaxies contains most of the neutral hydrogen gas over cosmic time. Few DLAs have been detected directly, which limits our knowledge of fundamental properties like size and mass. We present Keck/OSIRIS infrared integral field spectroscopy (IFU) observations of a DLA that was first detected in absorption toward a background quasar. Our observations use the Keck Laser Guide Star Adaptive Optics system to reduce the point-spread function of the quasar, making it possible to spatially resolve the DLA emission. We map this emission in O[III] 5007 Å. At redshift z~3, this DLA represents one of the highest redshift DLAs mapped with IFU spectroscopy. We present measurements of the star formation rate, metallicity, and gas mass of the galaxy.This project was supported in part by the NSF REU grant AST-1358980 and by the Nantucket Maria Mitchell Association.

  5. Extended Lyman-alpha emission from cold accretion streams

    CERN Document Server

    Rosdahl, J

    2011-01-01

    {Abridged} We investigate the observability of cold accretion streams at redshift 3 via Lyman-alpha radiation and the feasibility of cold accretion as the main driver behind giant Lya blobs (LABs). We run cosmological zoom simulations focusing on 3 halos spanning two orders of magnitude in mass, from 10^11 to 10^13 solar masses. We use a version of the AMR code Ramses that includes radiative transfer of UV photons, and we employ a refinement strategy that allows us to resolve accretion streams in their natural environment to an unprecedented level. For the first time, we self-consistently model self-shielding in the cold streams from the cosmological UV background, which enables us to accurately predict their temperatures, ionization states and Lya luminosities. We find the efficiency of gravitational heating in cold streams in a ~10^11 solar mass halo is around 10-20% throughout most of the halo but reaching much higher values close to the center. As a result most of the Lya luminosity comes from the circumg...

  6. Chemical evolution and nature of Damped Lyman-Alpha systems

    CERN Document Server

    Calura, F; Vladilo, G

    2003-01-01

    We study the nature of Damped Lyman -Alpha systems (DLAs) by means of a comparison between observed abundances and models of chemical evolution of galaxies of different morphological type. In particular, we compare for the first time the abundance ratios as functions of metallicity and redshift with dust-corrected data. We have developed detailed models following the evolution of several chemical elements (H, D, He, C, N, O, Ne, Mg, Si, S, Fe, Ni and Zn) for elliptical, spiral and irregular galaxies. Each of the models is calibrated to reproduce the main features of a massive elliptical, the Milky Way and the LMC, respectively. In addition, we run some models also for dwarf irregular starburst galaxies. All the models share the same uptodate nucleosynthesis prescriptions but differ in their star formation histories. The role of SNe of different type (II, Ia) is studied in each galaxy model together with detailed and up to date nucleosynthesis prescriptions. Our main conclusions are: 1) when dust depletion is ...

  7. Damped Lyman Alpha Systems in Galaxy Formation Simulations

    CERN Document Server

    Pontzen, Andrew; Pettini, Max; Booth, C M; Stinson, Greg; Wadsley, James; Brooks, Alyson; Quinn, Thomas; Haehnelt, Martin

    2008-01-01

    We investigate the population of z=3 damped Lyman alpha absorbers (DLAs) in a recent series of high resolution galaxy formation simulations. The simulations are of interest because they form at z=0 some of the most realistic disk galaxies to date. No free parameters are available in the simulations: these have been fixed by physical and z=0 observational constraints, and thus our study provides a genuine consistency test. The precise role of DLAs in galaxy formation remains in debate, but they provide a number of strong constraints on the nature of our simulated bound systems at z=3 because of their coupled information on neutral H I densities, kinematics, metallicity and estimates of star formation activity. Our results, without any parameter-tuning, closely match the observed incidence rate and column density distributions of DLAs. Our simulations are the first to reproduce the distribution of metallicities (with a median of Z_{DLA} = Z_{solar}/20) without invoking observationally unsupported mechanisms suc...

  8. The Lyman-alpha Forest as a Cosmological Tool

    CERN Document Server

    Weinberg, D H; Katz, N; Kollmeier, J A; Weinberg, David H.; Dav'e, Romeel; Katz, Neal; Kollmeier, Juna A.

    2003-01-01

    We review recent developments in the theory of the Lyman-alpha forest and their implications for the role of the forest as a test of cosmological models. Simulations predict a relatively tight correlation between the local Lya optical depth and the local gas or dark matter density. Statistical properties of the transmitted flux can constrain the amplitude and shape of the matter power spectrum at high redshift, test the assumption of Gaussian initial conditions, and probe the evolution of dark energy by measuring the Hubble parameter H(z). Simulations predict increased Lya absorption in the vicinity of galaxies, but observations show a Lya deficit within Delta_r ~ 0.5 Mpc/h (comoving). We investigate idealized models of "winds" and find that they must eliminate neutral hydrogen out to comoving radii ~1.5 Mpc/h to marginally explain the data. Winds of this magnitude suppress the flux power spectrum by \\~0.1 dex but have little effect on the distribution function or threshold crossing frequency. In light of the...

  9. The redshift evolution of Lyman-$\\alpha$ absorbers

    CERN Document Server

    Valageas, P; Silk, J

    1999-01-01

    We present a model for the Lyman-alpha absorbers that treats all objects (from the low-density forest clouds to the dense damped systems) in a unified description. This approach is consistent with an earlier model of galaxies (luminosity function, metallicity) but also with the known description of the density field in the small-scale non-linear regime. We consider two cosmological models: a critical universe $\\Omega=1$ with a CDM power-spectrum, and an open CDM universe with $\\Omega_0=0.3$, $\\Lambda=0$. We reproduce the available data on column density distribution as a function of redshift, the value of the main new parameter, the background ionizing UV flux, being consistent with the observed limits. This allows a quantitatively trustable analytical description of the opacity, mass, size, velocity dispersion and metallicity of these absorbers, over a range of column densities spanning 10 orders of magnitude. Moreover, together with an earlier model of galaxy formation this draws a unified picture of the re...

  10. Interplanetary Lyman $\\alpha$ line profiles: variations with solar activity cycle

    CERN Document Server

    Quemerais, E; Bertaux, J L; Koutroumpa, D; Clarke, J; Kyrola, E; Schmidt, W; Qu\\'emerais, Eric; Lallement, Rosine; Bertaux, Jean-Loup; Koutroumpa, Dimitra; Clarke, John; Kyrola, Erkki; Schmidt, Walter

    2006-01-01

    Interplanetary Lyman alpha line profiles are derived from the SWAN H cell data measurements. The measurements cover a 6-year period from solar minimum (1996) to after the solar maximum of 2001. This allows us to study the variations of the line profiles with solar activity. These line profiles were used to derive line shifts and line widths in the interplanetary medium for various angles of the LOS with the interstellar flow direction. The SWAN data results were then compared to an interplanetary background upwind spectrum obtained by STIS/HST in March 2001. We find that the LOS upwind velocity associated with the mean line shift of the IP \\lya line varies from 25.7 km/s to 21.4 km/s from solar minimum to solar maximum. Most of this change is linked with variations in the radiation pressure. LOS kinetic temperatures derived from IP line widths do not vary monotonically with the upwind angle of the LOS. This is not compatible with calculations of IP line profiles based on hot model distributions of interplanet...

  11. Lyman Alpha Signatures from Direct Collapse Black Holes

    CERN Document Server

    Dijkstra, Mark; Sobral, David

    2016-01-01

    `Direct collapse black holes' (DCBHs) provide possible seeds for supermassive black holes that exist at redshifts as high as z~7. We study Lyman Alpha (Lya) radiative transfer through simplified representations of the DCBH-scenario. We find that gravitational heating of the collapsing cloud gives rise to a Lya cooling luminosity of up to ~ 1e38(M_gas/1e6 Msun)^2 erg/s. The Lya production rate can be significantly larger during the final stages of collapse, but collisional deexcitation efficiently suppresses the emerging Lya flux. Photoionization by a central source boosts the Lya luminosity to L~1e43(M_BH/1e6 M_sun) erg/s during specific evolutionary stages of the cloud, where M_BH denotes the mass of the black hole powering this source. We predict that the width and velocity off-set of the Lya spectral line range from a few tens to few thousands km/s, depending sensitively on the evolutionary state of the cloud. We also compare our predictions to observations of CR7 (Sobral et al. 2015), a luminous Lya emitt...

  12. Lyman Alpha Emitters in the Hierarchically Clustering Galaxy Formation

    CERN Document Server

    Kobayashi, Masakazu A R; Nagashima, Masahiro

    2007-01-01

    We present a new theoretical model for the luminosity functions (LFs) of Lyman alpha (Lya) emitting galaxies in the framework of hierarchical galaxy formation. We extend a semi-analytic model of galaxy formation that reproduces a number of observations for local galaxies, without changing the original model parameters but introducing a physically-motivated modelling to describe the escape fraction of Lya photons from host galaxies (f_esc). Though a previous study using a hierarchical clustering model simply assumed a constant and universal value of f_esc, we incorporate two new effects on f_esc: extinction by interstellar dust and galaxy-scale outflow induced as a star formation feedback. It is found that the new model nicely reproduces all the observed Lya LFs of the Lya emitters (LAEs) at different redshifts in z ~ 3--6. Our model predicts that galaxies with strong outflows and f_esc ~ 1 are dominant in the observed LFs, which is consistent with available observations while the simple universal f_esc model ...

  13. The Metallicity evolution of Damped Lyman-$\\alpha$ systems

    CERN Document Server

    Savaglio, S; Stiavelli, M

    1999-01-01

    We have collected absorption line measurements of 70 Damped Lyman-alpha (DLA) systems, mostly coming from high resolution data, to investigate the chemical evolution of galaxies in the redshift interval 0.0 < z < 4.4. In doing that, we have adopted the most general approach used so far, i.e. the dust depletion corrections are obtained by comparing the element abundances with four depletion patterns observed in the Milky Way. The best solution, obtained through chi^2 minimization, gives as output parameters the global DLA metallicity and the dust-to-metals ratio. Clear evolution of the metallicity vs. redshift is found, with average values going from ~1/30 solar at z~4.1 to dispersion around the average regression is significantly larger than the errors (i.e. ~0.45 dex average dispersion relative to ~0.14 dex error), indicating that the class of DLAs include objects with a range of evolutionary histories and/or initial conditions, such as total mass, formation time, matter spatial distribution, etc. We a...

  14. Constraining the End of Reionization with Deep Lyman-alpha Spectroscopy

    Science.gov (United States)

    Jung, Intae; Finkelstein, Steven L.; Livermore, Rachael C.; Wold, Isak; Larson, Rebecca L.

    2017-06-01

    An immediately accessible method for studying the intergalactic medium in the reionization era is to measure the equivalent width distribution of Lyman-alpha emission from continuum-selected galaxies with follow-up spectroscopy. To search for Lyman-alpha emission from galaxies at z = 5.5-8.2, we are performing ultra-deep spectroscopic observations of candidate galaxies from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. We utilize data from the DEIMOS (optical) and MOSFIRE (near-infrared) spectrographs on the Keck 10-meter telescopes, ensuring the comprehensive wavelength coverage of Lyman-alpha emission at z ~ 6-8. We have a total of 1169 hours of spectroscopic integration of galaxies at z > 6: 738 hours for 123 galaxies with DEIMOS and 432 hours for 69 galaxies with MOSFIRE with the additional optical spectroscopic data of our sample galaxies in the GOODS-S field from VLT VANDELS survey. The Lyman-alpha fraction, the ratio of galaxies with detected Lyman-alpha emission to the number of all candidate galaxies observed, is directly measured with the completeness test of our data set by constructing detailed simulations of mock emission lines, which consider observational conditions (e.g., observational depth, wavelength coverage, and sky emission) and the probability distribution function of galaxy photometric redshifts. We present the early result on the Lyman-alpha emission equivalent width distribution of galaxies at z ~ 6 from our analysis of the DEIMOS spectroscopic dataset, determining robust upper limits on the Lyman-alpha emission.

  15. The Lyman alpha Reference Sample VI: Lyman alpha escape from the edge-on disk galaxy Mrk1486

    CERN Document Server

    Duval, Florent; Hayes, Matthew; Zackrisson, Erik; Verhamme, Anne; Orlitova, Ivana; Adamo, Angela; Guaita, Lucia; Melinder, Jens; Cannon, John M; Laursen, Peter; Rivera-Thorsen, Thoger; Herenz, E Christian; Gruyters, Pieter; Mas-Hesse, J Miguel; Kunth, Daniel; Sandberg, Andreas; Schaerer, Daniel; Mansson, Tore

    2015-01-01

    While numerical simulations suggest that the strength of the Lyman alpha (Lya) line of star-forming disk galaxies strongly depends on the inclination at which they are observed (i.e. from edge-on to face-on, we expect to see a change from an attenuated Lya line to a strong Lya emission line), recent observations with the Hubble space telescope (HST) have highlighted few low-redshift highly inclined (edge-on) disk galaxies that breaks this trend. We aim to understand how a strong Lya emission line is able to escape from one of those inclined disk galaxies, named Mrk1486 (z=0.0338). For that purpose we used a large set of HST imaging and spectroscopic data to investigate both the ISM structure and the dominant source of Lya radiation inside Mrk1486. Moreover, we used a 3D Monte Carlo Lya radiation transfer code to study the radiative transfer of Lya and UV continuum photons inside a 3D geometry of neutral hydrogen (HI) and dust that models the ISM structure at the galaxy center. The analysis of IFU Halpha spect...

  16. First Detection of Cosmic Microwave Background Lensing and Lyman-{\\alpha} Forest Bispectrum

    CERN Document Server

    Doux, Cyrille; Aubourg, Eric; Ganga, Ken; Lee, Khee-Gan; Spergel, David N; Tréguer, Julien

    2016-01-01

    We present the first detection of a correlation between the Lyman-$\\alpha$ forest and cosmic microwave background (CMB) lensing. For each Lyman-$\\alpha$ forest in SDSS-III/BOSS DR12, we correlate the one-dimensional power spectrum with the CMB lensing convergence on the same line of sight from Planck. This measurement constitutes a position-dependent power spectrum, or a squeezed bispectrum, and quantifies the non-linear response of the Lyman-$\\alpha$ forest power spectrum to a large-scale overdensity. The signal is measured at 5~$\\sigma$ and is consistent with the $\\Lambda$CDM expectation. We measure the linear and non-linear biases of the Lyman-$\\alpha$ forest with respect to the dark matter distribution. This new observable provides a consistency check for the Lyman-$\\alpha$ forest as a large-scale structure probe and tests our understanding of the relation between intergalactic gas and dark matter. In the future, it could be used to test hydrodynamical simulations and calibrate the relation between the Ly...

  17. Two-phase equilibrium and molecular hydrogen formation in damped Lyman-alpha systems

    CERN Document Server

    Liszt, H S

    2002-01-01

    Molecular hydrogen is quite underabundant in damped Lyman-alpha systems at high redshift, when compared to the interstellar medium near the Sun. This has been interpreted as implying that the gas in damped Lyman-alpha systems is warm. like the nearby neutral intercloud medium, rather than cool, as in the clouds which give rise to most H I absorption in the Milky Way. Other lines of evidence suggest that the gas in damped Lyman-alpha systems -- in whole or part -- is actually cool; spectroscopy of neutral and ionized carbon, discussed here, shows that the damped Lyman-alpha systems observed at lower redshift z $$ 2.8 are warm (though not devoid of H2). To interpret the observations of carbon and hydrogen we constructed detailed numerical models of H2 formation under the conditions of two-phase thermal equilibrium, like those which account for conditions near the Sun, but with varying metallicity, dust-gas ratio, $etc$. We find that the low metallicity of damped Lyman-alpha systems is enough to suppress H2 form...

  18. Computing Intrinsic Lyman-alpha Fluxes of F5 V to M5 V Stars

    CERN Document Server

    Linsky, Jeffrey L; Ayres, Tom

    2013-01-01

    The Lyman-alpha emission line dominates the far-ultraviolet spectra of late-type stars and is a major source for photodissociation of important molecules including H2O, CH4, and CO2 in exoplanet atmospheres. The incident flux in this line illuminating an exoplanet's atmosphere cannot be measured directly as neutral hydrogen in the interstellar medium (ISM) attenuates most of the flux reaching the Earth. Reconstruction of the intrinsic Lyman-alpha line has been accomplished for a limited number of nearby stars, but is not feasible for distant or faint host stars. We identify correlations connecting the intrinsic Lyman-alpha flux with the flux in other emission lines formed in the stellar chromosphere, and find that these correlations depend only gradually on the flux in the other lines. These correlations, which are based on HST spectra, reconstructed Lyman-alpha line fluxes, and irradiance spectra of the quiet and active Sun, are required for photochemical models of exoplanet atmospheres when intrinsic Lyman-...

  19. Minimally Parametric Power Spectrum Reconstruction from the Lyman-alpha Forest

    CERN Document Server

    Bird, Simeon; Viel, Matteo; Verde, Licia

    2010-01-01

    Current results from the Lyman alpha forest assume that the primordial power spectrum of density perturbations follows a simple power law form. We present the first analysis of Lyman alpha data to study the effect of relaxing this strong assumption on primordial and astrophysical constraints. We perform a large suite of numerical simulations, using them to calibrate a minimally parametric framework for describing the power spectrum. Combined with cross-validation, a statistical technique which prevents over-fitting of the data, this framework allows us to reconstruct the power spectrum shape without strong prior assumptions. We find no evidence for deviation from scale-invariance; our analysis also shows that current Lyman alpha data do not have sufficient statistical power to robustly probe the shape of the power spectrum at these scales. In contrast, the ongoing Baryon Oscillation Sky Survey (BOSS) will be able to do so with high precision. Furthermore, this near-future data will be able to break degeneraci...

  20. Lyman alpha emission from the first galaxies : signatures of accretion and infall in the presence of line trapping

    NARCIS (Netherlands)

    Latif, M. A.; Schleicher, Dominik R. G.; Spaans, M.; Zaroubi, S.

    2011-01-01

    The formation of the first galaxies is accompanied by large accretion flows and virialization shocks, during which the gas is shock heated to temperatures of similar to 10(4) K, leading to potentially strong fluxes in the Lyman alpha line. Indeed, a number of Lyman alpha blobs have been detected at

  1. Oxygen sensitivity of krypton and Lyman-alpha hygrometers

    NARCIS (Netherlands)

    Dijk, van A.; Kohsiek, W.; Bruin, de H.A.R.

    2003-01-01

    The oxygen sensitivity of krypton and Lyman-¿ hygrometers is studied. Using a dewpoint generator and a controlled nitrogen/oxygen flow the extinction coefficients of five hygrometers associated with the third-order Taylor expansion of the Lambert¿Beer law around reference conditions for oxygen and f

  2. Lyman-alpha and CIII] Emission in z=7-9 Galaxies: Accelerated Reionization Around Luminous Star Forming Systems?

    CERN Document Server

    Stark, Daniel P; Charlot, Stephane; Chevallard, Jacopo; Tang, Mengtao; Belli, Sirio; Zitrin, Adi; Mainali, Ramesh; Gutkin, Julia; Vidal-Garcia, Alba; Bouwens, Rychard; Oesch, Pascal

    2016-01-01

    We discuss new Keck/MOSFIRE spectroscopic observations of four luminous galaxies at z~7-9 selected to have intense optical line emission by Roberts-Borsani et al. (2016). Previous follow-up has revealed Lyman-alpha in two of the four galaxies. Our new MOSFIRE observations confirm that Lyman-alpha is present in the entire sample. We detect Lyman-alpha emission in COS-zs7-1, confirming its redshift as z=7.154, and we detect Lyman-alpha in EGS-zs8-2 at z=7.477, verifying a tentative detection presented in an earlier study. The ubiquity of Lyman-alpha in this sample is puzzling given that the IGM is likely significantly neutral over 77 is expected to be strongly luminosity-dependent, with the most effective transmission occurring in systems with intense star formation.

  3. The most metal-rich damped Lyman alpha systems at z>1.5 I: The Data

    CERN Document Server

    Berg, Trystyn A M; Prochaska, J Xavier; Ellison, Sara L; Wolfe, Arthur M

    2014-01-01

    We present HIRES observations for 30 damped Lyman alpha systems, selected on the basis of their large metal column densities from previous, lower resolution data. The measured metal column densities for Fe, Zn, S, Si, Cr, Mn, and Ni are provided for these 30 systems. Combined with previously observed large metal column density damped Lyman alpha systems, we present a sample of 44 damped Lyman alpha systems observed with high resolution spectrographs (R~30000). These damped Lyman alpha systems probe the most chemically evolved systems at redshifts greater than 1.5. We discuss the context of our sample with the general damped Lyman alpha population, demonstrating that we are probing the top 10% of metal column densities with our sample. In a companion paper, we will present an analysis of the sample's elemental abundances in the context of galactic chemical enrichment.

  4. Predicting Lyman-alpha and Mg II Fluxes from K and M Dwarfs Using GALEX Ultraviolet Photometry

    CERN Document Server

    Shkolnik, Evgenya L; Peacock, Sarah; Barman, Travis S

    2014-01-01

    A star's UV emission can greatly affect the atmospheric chemistry and physical properties of closely orbiting planets with the potential for severe mass loss. In particular, the Lyman-alpha emission line at 1216 Angstroms, which dominates the far-ultraviolet spectrum, is a major source of photodissociation of important atmospheric molecules such as water and methane. The intrinsic flux of Lyman-alpha, however, cannot be directly measured due to the absorption of neutral hydrogen in the interstellar medium and contamination by geocoronal emission. To date, reconstruction of the intrinsic Lyman-alpha line based on Hubble Space Telescope spectra has been accomplished for 46 FGKM nearby stars, 28 of which have also been observed by the Galaxy Evolution Explorer (GALEX). Our investigation provides a correlation between published intrinsic Lyman-alpha and GALEX far- and near-ultraviolet chromospheric fluxes for K and M stars. The negative correlations between the ratio of the Lyman-alpha to the GALEX fluxes reveal ...

  5. An Ultraluminous Lyman Alpha Emitter with a Blue Wing at z=6.6

    CERN Document Server

    Hu, E M; Songaila, A; Barger, A J; Rosenwasser, B; Wold, I

    2016-01-01

    We report the detection of the most luminous high-redshift Lyman Alpha Emitting galaxy (LAE) yet seen, with log L(Ly alpha) = 43.9 ergs/s. The galaxy -- COSMOS Lyman alpha 1, or COLA1 -- was detected in a search for ultra-luminous LAEs with Hyper Suprime-Cam on the Subaru telescope. It was confirmed to lie at z = 6.593 based on a Lyman alpha line detection obtained from followup spectroscopy with the DEIMOS spectrograph on Keck2. COLA1 is the first very high-redshift LAE to show a multi-component Lyman alpha line profile with a blue wing, which suggests that it could lie in a highly ionized region of the intergalactic medium and could have significant infall. If this interpretation is correct, then ultra-luminous LAEs like COLA1 offer a unique opportunity to determine the properties of the HII regions around these galaxies which will help in understanding the ionization of the z ~ 7 intergalactic medium.

  6. Variability of Lyman-alpha and the ultraviolet continuum of 3C 446

    Science.gov (United States)

    Bregman, J. N.; Glassgold, A. E.; Huggins, P. J.; Kinney, A. L.

    1986-01-01

    IUE observations have been conducted over the 1230-3175 A range for the violently variable quasar 3C 446, beginning in June 1980, at intervals of 1.2, 2.2, 0.5, and 0.4 yr. Strong absorption of the continuum was found below 1830 A, probably corresponding to a Lyman edge at z of 1.00 + or - 0.01. The absence of Mg II 2798 A absorption implies that the column density is in the lower end of the range, unless the gas is metal-poor. The Lyman-alpha emission line was detected in five spectra; relative to the number of ionizing protons, the line strengths are the same as in normal quasars, and line equivalent widths are small due to the continuum's rise redward of 912 A, which is much steeper than in normal quasars. The Lyman-alpha line and the nearby continuum vary so as to maintain constant equivalent width.

  7. Bias, redshift space distortions and primordial nongaussianity of nonlinear transformations: application to Lyman alpha forest

    CERN Document Server

    Seljak, Uros

    2012-01-01

    On large scales a nonlinear transformation of matter density field can be viewed as a biased tracer of the density field itself. A nonlinear transformation also modifies the redshift space distortions in the same limit, giving rise to a velocity bias. In models with primordial nongaussianity a nonlinear transformation generates a scale dependent bias on large scales. We derive analytic expressions for these for a general nonlinear transformation. These biases can be expressed entirely in terms of the one point distribution function (PDF) of the final field and the parameters of the transformation. Our analysis allows one to devise nonlinear transformations with nearly arbitrary bias properties, which can be used to increase the signal in the large scale clustering limit. We apply the results to the ionizing equilibrium model of Lyman-alpha forest, in which Lyman-alpha flux F is related to the density perturbation delta via a nonlinear transformation. Velocity bias can be expressed as an average over the Lyman...

  8. Cross-correlation of the cosmic 21-cm signal and Lyman Alpha Emitters during reionization

    CERN Document Server

    Sobacchi, Emanuele; Greig, Bradley

    2016-01-01

    Interferometry of the cosmic 21-cm signal is set to revolutionize our understanding of the Epoch of Reionization (EoR), eventually providing 3D maps of the early Universe. Initial detections however will be low signal-to-noise, limited by systematics. To confirm a putative 21-cm detection, and check the accuracy of 21-cm data analysis pipelines, it would be very useful to cross-correlate against a genuine cosmological signal. The most promising cosmological signals are wide-field maps of Lyman alpha emitting galaxies (LAEs), expected from the Subaru Hyper-Suprime Cam (HSC) Ultra-Deep field. Here we present estimates of the correlation between LAE maps at z~7 and the 21-cm signal observed by both the Low Frequency Array (LOFAR) and the planned Square Kilometer Array Phase 1 (SKA1). We adopt a systematic approach, varying both: (i) the prescription of assigning LAEs to host halos; and (ii) the large-scale structure of neutral and ionized regions (i.e. EoR morphology). We find that the LAE-21cm cross-correlation...

  9. The LyAlpha Line Profiles of Ultraluminous Infrared Galaxies: Fast Winds and Lyman Continuum Leakage

    CERN Document Server

    Martin, Crystal L; Henry, Alaina; Soto, Kurt T; Danforth, Charles W; Wong, Joseph

    2015-01-01

    We present new Hubble Space Telescope Cosmic Origins Spectrograph far-ultraviolet (far-UV) spectroscopy and Keck Echellete optical spectroscopy of 11 ultraluminous infrared galaxies (ULIRGs), a rare population of local galaxies experiencing massive gas inflows, extreme starbursts, and prominent outflows. We detect H Lyman alpha emission from 8 ULIRGs and the companion to IRAS09583+4714. In contrast to the P Cygni profiles often seen in galaxy spectra, the H Lyman alpha profiles exhibit prominent, blueshifted emission out to Doppler shifts exceeding -1000 km/s in three HII-dominated and two AGN-dominated ULIRGs. To better understand the role of resonance scattering in shaping the H Lyman alpha line profiles, we directly compare them to non-resonant emission lines in optical spectra. We find that the line wings are already present in the intrinsic nebular spectra, and scattering merely enhances the wings relative to the line core. The H Lyman alpha attenuation (as measured in the COS aperture) ranges from that ...

  10. Diagnosing galactic feedback with the line broadening in the low redshift Lyman-alpha forest

    CERN Document Server

    Viel, M; Bolton, J S; Kim, T -S; Puchwein, E; Nasir, F; Wakker, B P

    2016-01-01

    We compare the low redshift (z ~ 0.1) Lyman-alpha forest from hydrodynamical simulations with data from the Cosmic Origin Spectrograph (COS). We find tension between the observed number of lines with b-parameters in the range 25-45 km/s and the predictions from simulations that incorporate either vigorous feedback from active galactic nuclei or that exclude feedback altogether. The gas in these simulations is, respectively, either too hot to contribute to the Lyman-alpha absorption or too cold to produce the required line widths. Matching the observed b-parameter distribution therefore requires feedback processes that thermally or turbulently broaden the absorption features without collisionally (over-)ionising hydrogen. This suggests the Lyman-alpha forest b-parameter distribution is a valulable diagnostic of galactic feedback in the low redshift Universe. We furthermore confirm the low redshift Lyman-alpha forest column density distribution is better reproduced by an ultraviolet background with an HI photo-...

  11. A deep search for 21-cm absorption in high redshift damped Lyman-alpha systems

    NARCIS (Netherlands)

    Kanekar, N; Chengalur, JN

    2003-01-01

    We present deep GMRT 21-cm absorption spectra of 10 damped Lyman-alpha systems (DLAs), of which 8 are at redshifts zgreater than or similar to1.3. HI absorption was detected in only one DLA, the z=0.5318 absorber toward PKS 1629+12. This absorber has been identified with a luminous spiral galaxy; th

  12. Lyman alpha emission from the first galaxies: Implications of UV backgrounds and the formation of molecules

    CERN Document Server

    Latif, M A; Spaans, M; Zaroubi, S

    2011-01-01

    The Lyman alpha line is a robust tracer of high redshift galaxies. We present estimates of Lyman alpha emission from a protogalactic halo illuminated by UV background radiation fields with various intensities. For this purpose, we performed cosmological hydrodynamics simulations with the adaptive mesh refinement code FLASH, including a detailed network for primordial chemistry,comprising the formation of primordial molecules, a multi-level model for the hydrogen atom as well as the photo-ionization and photo-dissociation processes in a UV background. We find that the presence of a background radiation field J_21 excites the emission of Lyman alpha photons, increasing the Lyman alpha luminosity up to two orders of magnitude. For a halo of \\sim 10^10 M_sun, we find that a maximum flux of 5 \\times 10^-15 erg cm^-2 s^-1 is obtained for J21 \\times f_esc = 0.1, where f_esc is the escape fraction of the ionizing radiation. Depending on the environmental conditions, the flux may vary by three orders of magnitude. For...

  13. A Lyman-alpha tunable acousto-optic filter for detecting superthermal flare protons

    Science.gov (United States)

    Mickey, Donald L.

    1994-01-01

    The goal of this project was to develop and characterize a narrow-band, tunable filter for use near the Lyman-alpha line of hydrogen at 121.6 nm. Such a filter could form the critical component of an instrument to observe asymmetries in the solar Lyman-alpha line, caused by energetic protons accelerated during the impulsive phase of solar flares. Characteristic charge-exchange nonthermal emission at Lyman alpha should be produced when sub-MeV protons are injected into the chromosphere, but no instrument suitable for their detection has been developed. Such an instrument would require a narrow-band (less than 0.01 nm) tunable filter with aperture and throughput consistent with imaging a solar active region at 0.1 second intervals. The development of acousto-optic tunable filters (AOTF) suitable for use as compact, simple tunable filters for astronomical work suggested an investigation into the use of an AOTF at Lyman-alpha.

  14. Lyman alpha line formation in starbursting galaxies I. Moderately thick, dustless, and static HI media

    CERN Document Server

    Ahn, S H; Lee, H M; Ahn, Sang-Hyeon; Lee, Hee-Won; Lee, Hyung Mok

    2000-01-01

    We investigate the Lyman alpha line transfer in nearby and high redshift starbursting galaxies, where the effect of high optical depths and the role of dust in the scattering medium are expected to be conspicuous and should be treated in a very careful manner. We present our first results in dustless, static, and uniform HI media with moderate optical depths \\tau_0=10^{3-7}, where \\tau_0 is the line center optical depth of Lyman alpha and temperatures T=10^{1-4}K using a Monte Carlo code. We investigate the basic physics of the line transfer and confirm the criterion of a\\tau_0>10^3 for the validity of diffusion approximation suggested by Neufeld in 1990, where $a$ is the Voigt parameter. Adopting the model suggested by Tenorio-Tagle et al. in 1999, we performed a detailed calculation on the Lyman alpha line formation for each evolutionary stage of an expanding supershell. The emergent Lyman alpha profiles are characterized by the double peaks and the absorption trough at the line center. It is found that the...

  15. A Search for z>6.5 Lyman-alpha Emitting Galaxies with WISP

    Science.gov (United States)

    Bagley, Micaela B.; Scarlata, Claudia; Dai, Yu Sophia; Rafelski, Marc; Baronchelli, Ivano; Colbert, James W.; Dominguez, Alberto; Hathi, Nimish P.; Henry, Alaina L.; Malkan, Matthew Arnold; Martin, Crystal L.; Mehta, Vihang; Pahl, Anthony; Ross, Nathaniel; Rutkowski, Michael J.; Teplitz, Harry I.; WISP Team

    2016-01-01

    The observed number density of Lyman-alpha emitting galaxies at z>6 provides an important probe of the reionization history of the universe. Because Lyman-alpha photons are very sensitive to the presence of neutral hydrogen, the evolution of the galaxy number density above redshift 6 can be used as a measurement on the progress of reionization. However, the Lyman-alpha luminosity function is currently poorly constrained at high-z. We present the results of a systematic search for Lyman-alpha emitters (LAEs) at redshifts of ~6.5 to 7.5 using the HST WFC3 Infrared Spectroscopic Parallels (WISP) survey. WISP's uncorrelated fields are well-suited to the study of bright LAEs, minimizing the effects of clustering introduced by a patchy reionization. From the 30 deepest WISP fields, we compile a sample of single-line emitters, confirm redshifts with broadband colors, and identify LAE candidates that have "dropped out" (are undetected at the 1 sigma level) of the WFC3 UVIS filters. By combining our results with other z~7 studies, we determine whether the number density of LAEs evolves past z~6.5.

  16. The Lyman-alpha forest in f(R) modified gravity

    CERN Document Server

    Arnold, Christian; Springel, Volker

    2014-01-01

    In this work, we analyze the Lyman-$\\alpha$ forest in cosmological hydrodynamical simulations of chameleon-type f(R) gravity with the goal to assess whether the impact of such models is detectable in absorption line statistics. We carry out a set of hydrodynamical simulations with the cosmological simulation code MG-GADGET, including star formation and cooling effects, and create synthetic Lyman-$\\alpha$ absorption spectra from the simulation outputs. We statistically compare simulations with f(R) and ordinary general relativity, focusing on flux probability distribution functions (PDFs) and flux power-spectra, an analysis of the column density and line width distributions, as well as the matter power spectrum. We find that the influence of f(R) gravity on the Lyman-$\\alpha$ forest is rather small. Even models with strong modifications of gravity, like $|\\bar{f}_{R0}| = 10^{-4}$, do not change the statistical Lyman-$\\alpha$ properties by more than 10%. The column density and line width distributions are hardl...

  17. Clustering and lifetime of Lyman Alpha Emitters in the Epoch of Reionization

    CERN Document Server

    Hutter, Anne; Müller, Volker

    2015-01-01

    We calculate Lyman Alpha Emitter (LAE) angular correlation functions (ACFs) at $z\\simeq6.6$ and the fraction of lifetime (for the 100 Myrs preceding $z\\simeq6.6$) galaxies spend as Lyman Break Galaxies (LBGs) with/without Lyman Alpha (Ly\\alpha) emission using a model that combines SPH cosmological simulations (GADGET-2), dust attenuation and a radiative transfer code (pCRASH). The ACFs are a powerful tool that significantly narrows the 3D parameter space allowed by LAE Ly$\\alpha$ and UV luminosity functions (LFs) alone. With this work, we simultaneously constrain the escape fraction of ionizing photons $f_{esc}=0.05-0.5$, the mean fraction of neutral hydrogen in the intergalactic medium (IGM) $\\leq 0.01$ and the dust-dependent ratio of the escape fractions of Ly$\\alpha$ and UV continuum photons $f_\\alpha/f_c=0.6-1.2$. Our results show that reionization has the largest impact on the amplitude of the ACFs, and its imprints are clearly distinguishable from those of $f_{esc}$ and $f_\\alpha/f_c$. We also show that...

  18. The Impact of Different Physical Processes on the Statistics of Lyman-limit and Damped Lyman-alpha Absorbers

    CERN Document Server

    Altay, Gabriel; Schaye, Joop; Booth, C M; Vecchia, Claudio Dalla

    2013-01-01

    We compute the z = 3 neutral hydrogen column density distribution function f(NHI) for 19 simulations drawn from the OWLS project using a post-processing correction for self-shielding calculated with full radiative transfer of the ionising background radiation. We investigate how different physical processes and parameters affect the abundance of Lyman-limit systems (LLSs) and damped Lyman-alpha absorbers (DLAs) including: i) metal-line cooling; ii) the efficiency of feedback from SNe and AGN; iii) the effective equation of state for the ISM; iv) cosmological parameters; v) the assumed star formation law and; vi) the timing of hydrogen reionization . We find that the normalisation and slope, D = d log10 f /d log10 NHI, of f(NHI) in the LLS regime are robust to changes in these physical processes. Among physically plausible models, f(NHI) varies by less than 0.2 dex and D varies by less than 0.18 for LLSs. This is primarily due to the fact that these uncertain physical processes mostly affect star-forming gas w...

  19. Studying Lyman-alpha escape and reionization in Green Pea galaxies

    Science.gov (United States)

    Yang, Huan; Malhotra, Sangeeta; Rhoads, James E.; Gronke, Max; Leitherer, Claus; Wofford, Aida; Dijkstra, Mark

    2017-01-01

    Green Pea galaxies are low-redshift galaxies with extreme [OIII]5007 emission line. We built the first statistical sample of Green Peas observed by HST/COS and used them as analogs of high-z Lyman-alpha emitters to study Ly-alpha escape and Ly-alpha sizes. Using the HST/COS 2D spectra, we found that Ly-alpha sizes of Green Peas are larger than the UV continuum sizes. We found many correlations between Ly-alpha escape fraction and galactic properties -- dust extinction, Ly-alpha kinematic features, [OIII]/[OII] ratio, and gas outflow velocities. We fit an empirical relation to predict Ly-alpha escape fraction from dust extinction and Ly-alpha red-peak velocity. In the JWST era, we can use this relation to derive the IGM HI column density along the line of sight of each high-z Ly-alpha emitter and probe the reionization process.

  20. Lyman-alpha radiation hydrodynamics of galactic winds before cosmic reionization

    CERN Document Server

    Smith, Aaron; Loeb, Abraham

    2016-01-01

    The dynamical impact of Lyman-alpha (Ly{\\alpha}) radiation pressure on galaxy formation depends on the rate and duration of momentum transfer between Ly{\\alpha} photons and neutral hydrogen gas. Although photon trapping has the potential to multiply the effective force, ionizing radiation from stellar sources may relieve the Ly{\\alpha} pressure before appreciably affecting the kinematics of the host galaxy or efficiently coupling Ly{\\alpha} photons to the outflow. We present self-consistent Ly{\\alpha} radiation-hydrodynamics simulations of high-$z$ galaxy environments by coupling the Cosmic Ly{\\alpha} Transfer code (COLT) with spherically symmetric Lagrangian frame hydrodynamics. The accurate but computationally expensive Monte-Carlo radiative transfer calculations are feasible under the one-dimensional approximation. In certain cases Ly{\\alpha} feedback significantly enhances the velocity of the shell of gas expanding around a central source. Radiative feedback alone is capable of ejecting baryons into the i...

  1. ALMA observations of Lyman-alpha Blob 1: halo sub-structure illuminated from within

    CERN Document Server

    Geach, J E; Matsuda, Y; Hayes, M; Mas-Ribas, Ll; Dijkstra, M; Steidel, C C; Chapman, S C; Feldmann, R; Avison, A; Agertz, O; Ao, Y; Birkinshaw, M; Bremer, M N; Clements, D L; Dannerbauer, H; Farrah, D; Harrison, C M; Hine, N K; Kubo, M; Michalowski, M J; Scott, Douglas; Smith, D J B; Spaans, M; Simpson, J M; Swinbank, A M; Taniguchi, Y; van Kampen, E; van der Werf, P; Verma, A; Yamada, T

    2016-01-01

    We present new Atacama Large Millimeter/Submillimeter Array (ALMA) 850um continuum observations of the original Lyman-alpha Blob (LAB) in the SSA22 field at z=3.1 (SSA22-LAB01). The ALMA map resolves the previously identified submillimeter source into three components with total flux density S_850 = 1.68+/-0.06 mJy, corresponding to a star formation rate of ~150 M_sun/yr. The submillimeter sources are associated with several faint (m~27 mag) rest-frame ultraviolet sources identified in Hubble Space Telescope Imaging Spectrograph (STIS) clear filter imaging (~5850A). One of these companions is spectroscopically confirmed with Keck MOSFIRE to lie within 20 projected kpc and 250 km/s of one of the ALMA components. We postulate that some of these STIS sources represent a population of low-mass star-forming satellites surrounding the central submillimeter sources, potentially contributing to their growth and activity through accretion. Using a high resolution cosmological zoom simulation of a 10^13 M_sun halo at z...

  2. Polar solar wind and interstellar wind properties from interplanetary Lyman-alpha radiation measurements

    Science.gov (United States)

    Witt, N.; Blum, P. W.; Ajello, J. M.

    1981-01-01

    The analysis of Mariner 10 observations of Lyman-alpha resonance radiation shows an increase of interplanetary neutral hydrogen densities above the solar poles. This increase is caused by a latitudinal variation of the solar wind velocity and/or flux. Using both the Mariner 10 results and other solar wind observations, the values of the solar wind flux and velocity with latitude are determined for several cases of interest. The latitudinal variation of interplanetary hydrogen gas, arising from the solar wind latitudinal variation, is shown to be most pronounced in the inner solar system. From this result it is shown that spacecraft Lyman-alpha observations are more sensitive to the latitudinal anisotropy for a spacecraft location in the inner solar system near the downwind axis.

  3. Lyman alpha emission from the first galaxies: Signatures of accretion and infall in the presence of line trapping

    CERN Document Server

    Latif, M A; Spaans, M; Zaroubi, S

    2011-01-01

    The formation of the first galaxies is accompanied by large accretion flows and virialization shocks, during which the gas is shock-heated to temperatures of $\\sim10^4$ K, leading to potentially strong fluxes in the Lyman alpha line. Indeed, a number of Lyman alpha blobs has been detected at high redshift. In this letter, we explore the origin of such Lyman alpha emission using cosmological hydrodynamical simulations that include a detailed model of atomic hydrogen as a multi-level atom and the effects of line trapping with the adaptive mesh refinement code FLASH. We see that baryons fall into the center of a halo through cold streams of gas, giving rise to a Lyman alpha luminosity of at least $\\rm 10^{44} erg s^{-1}$ at $\\rm z=4.7$, similar to observed Lyman alpha blobs. We find that a Lyman alpha flux of $\\rm 5.0\\times 10^{-17} erg cm^{-2} s^{-1}$ emerges from the envelope of the halo rather than its center, where the photons are efficiently trapped. Such emission can be probed in detail with the upcoming J...

  4. Performance Characterization of UV Science Cameras Developed for the Chromospheric Lyman-Alpha Spectro-Polarimeter

    Science.gov (United States)

    Champey, P.; Kobayashi, K.; Winebarger, A.; Cirtain, J.; Hyde, D.; Robertson, B.; Beabout, D.; Beabout, B.; Stewart, M.

    2014-01-01

    The NASA Marshall Space Flight Center (MSFC) has developed a science camera suitable for sub-orbital missions for observations in the UV, EUV and soft X-ray. Six cameras will be built and tested for flight with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), a joint National Astronomical Observatory of Japan (NAOJ) and MSFC sounding rocket mission. The goal of the CLASP mission is to observe the scattering polarization in Lyman-alpha and to detect the Hanle effect in the line core. Due to the nature of Lyman-alpha polarization in the chromosphere, strict measurement sensitivity requirements are imposed on the CLASP polarimeter and spectrograph systems; science requirements for polarization measurements of Q/I and U/I are 0.1 percent in the line core. CLASP is a dual-beam spectro-polarimeter, which uses a continuously rotating waveplate as a polarization modulator, while the waveplate motor driver outputs trigger pulses to synchronize the exposures. The CCDs are operated in frame-transfer mode; the trigger pulse initiates the frame transfer, effectively ending the ongoing exposure and starting the next. The strict requirement of 0.1 percent polarization accuracy is met by using frame-transfer cameras to maximize the duty cycle in order to minimize photon noise. Coating the e2v CCD57-10 512x512 detectors with Lumogen-E coating allows for a relatively high (30 percent) quantum efficiency at the Lyman-alpha line. The CLASP cameras were designed to operate with 10 e-/pixel/second dark current, 25 e- read noise, a gain of 2.0 +/- 0.5 and 1.0 percent residual non-linearity. We present the results of the performance characterization study performed on the CLASP prototype camera; dark current, read noise, camera gain and residual non-linearity.

  5. A study of the Lyman-$\\alpha$ line profile in DBA white dwarfs

    CERN Document Server

    Genest-Beaulieu, C

    2016-01-01

    The hydrogen abundances in DBA white dwarfs determined from optical or UV spectra have been reported to differ significantly in some studies. We revisit this problem using our own model atmospheres and synthetic spectra, and present a theoretical investigation of the Lyman-$\\alpha$ line profile as a function of effective temperature and hydrogen abundance. We identify one possible solution to this discrepancy and show considerable improvement from a detailed analysis of optical and UV spectra of DBA stars.

  6. Coupling the emission of ionizing radiation and Lyman alpha

    Science.gov (United States)

    Hayes, Matthew

    2013-10-01

    The class of objects that reionized intergalactic hydrogen remains an observational and theoretical problem that is in contention for being the most prominent puzzle piece in contemporary astrophysics. The current consensus - determined almost entirely by ruling out bright active galaxies - is that the process was possibly begun and almost certainly finished by faint, lower-mass galaxies forming their early generations of stars. Recent observations of z 3 galaxies may even have identified the analog populations.However understanding how the emitted ionizing power of galaxies is causally related to their {robustly determined} physical properties is not a study that can be performed at high-z: neither the spatial information nor the standard multi-wavelength diagnostics are available. Moreover, on a case-by-case basis, the intervening IGM absorption is impossible to determine. These considerations have spawned a number of detailed studies with UV space telescopes, the synthesis of which however is that a characteristic population of Lyman continuum {LyC} emitting objects has not yet been identified. We show in this proposal that we have identified a characteristic trait in galaxy spectra that is highly indicative of LyC emission, by combining {a} high-z phenomenological studies, {b} new high-resolution UV spectra of local galaxies, and {c} sophisticated models of radiation transport. Believing that we have determined the signature, we propose to test the new hypothesis with deep spectroscopic observations with HST/COS under the Cycle 21 UV initiative.

  7. The Lyman Alpha Imaging-Monitor Experiment (LAIME) for TESIS/CORONAS-PHOTON

    Science.gov (United States)

    Damé, L.; Koutchmy, S.; Kuzin, S.; Lamy, P.; Malherbe, J.-M.; Noëns, J.-C.

    LAIME the Lyman Alpha Imaging-Monitor Experiment is a remarkably simple no mechanisms and compact 100x100x400 mm full Sun imager to be flown with TESIS on the CORONAS-PHOTON mission launch expected before mid-2008 As such it will be the only true chromospheric imager to be flown in the next years supporting TESIS EUV-XUV imaging SDO and the Belgian LYRA Lyman Alpha flux monitor on the ESA PROBA-2 microsatellite launch expected in September 2007 We will give a short description of this unique O60 mm aperture imaging telescope dedicated to the investigating of the magnetic sources of solar variability in the UV and chromospheric and coronal disruptive events rapid waves Moreton waves disparitions brusques of prominences filaments eruptions and CMEs onset The resolution pixel is 2 7 arcsec the field of view 1 4 solar radius and the acquisition cadence could be as high as 1 image minute The back thinned E2V CCD in the focal plane is using frame transfer to avoid shutter and mechanisms Further more the double Lyman Alpha filtering allows a 40 AA FWHM bandwidth and excellent rejection yet providing a vacuum seal design of the telescope MgF2 entrance window Structural stability of the telescope focal length 1 m is preserved by a 4-INVAR bars design with Aluminium compensation in a large pm 10 o around 20 o

  8. No Evidence for Lyman-alpha Emission in Spectroscopy of z > 7 Candidate Galaxies

    CERN Document Server

    Caruana, Joseph; Wilkins, Stephen M; Stanway, Elizabeth R; Lacy, Mark; Jarvis, Matt J; Lorenzoni, Silvio; Hickey, Samantha

    2012-01-01

    We present Gemini/GNIRS spectroscopic observations of 4 z-band (z~7) dropout galaxies and VLT/XSHOOTER observations of one z-band dropout and 3 Y-band (z~8-9) dropout galaxies in the Hubble Ultra Deep Field, which were selected with Wide Field Camera 3 imaging on the Hubble Space Telescope. We find no evidence of Lyman-alpha emission with a typical 5-sigma sensitivity of 5X10^-18erg/cm^2/s, and we use the upper limits on Lyman-alpha flux and the broad-band magnitudes to constrain the rest-frame equivalent widths for this line emission. Accounting for incomplete spectral coverage, we survey 3.0 z-band dropouts and 2.9 Y-band dropouts to a Lyman-alpha rest-frame equivalent width limit > 120Ang (for an unresolved emission line); for an equivalent width limit of 50Ang the effective numbers of drop-outs surveyed fall to 1.2 z-band drop-outs and 1.5 Y-band drop-outs. A simple model where the fraction of high rest-frame equivalent width emitters follows the trend seen at z=3-6.5 is inconsistent with our non-detectio...

  9. The Impact of Lyman alpha Trapping on the Formation of Primordial Objects

    CERN Document Server

    Latif, M A; Spaans, M

    2010-01-01

    Numerous cosmological simulations have been performed to study the formation of the first objects. We present the results of high resolution 3-D cosmological simulations of primordial objects formation using the adaptive mesh refinement code FLASH by including in an approximate manner the radiative transfer effects of Lyman alpha photons. We compare the results of a Lyman alpha trapping case inside gas clouds with atomic and molecular hydrogen cooling cases.The principal objective of this research is to follow the collapse of a zero metallicity halo with an effective equation of state (that accounts for the trapping) and to explore the fate of a halo in each of the three cases, specifically, the impact of thermodynamics on fragmentation of halos.Our results show that in the case of Lyman alpha trapping, fragmentation is halted and a massive object is formed at the center of a halo. The temperature of the gas remains well above $10^{4}$ K and the halo is not able to fragment to stellar masses. In the atomic co...

  10. Chemistry of a protoplanetary disk with grain settling and Lyman alpha radiation

    CERN Document Server

    Fogel, Jeffrey K J; Bergin, Edwin A; Calvet, Nuria; Semenov, Dmitry

    2010-01-01

    We present results from a model of the chemical evolution of protoplanetary disks. In our models we directly calculate the changing propagation and penetration of a high energy radiation field with Lyman alpha radiation included. We also explore the effect on our models of including dust grain settling. We find that, in agreement with earlier studies, the evolution of dust grains plays a large role in determining how deep the UV radiation penetrates into the disk. Significant grain settling at the midplane leads to much smaller freeze-out regions and a correspondingly larger molecular layer, which leads to an increase in column density for molecular species such as CO, CN and SO. The inclusion of Lyman alpha radiation impacts the disk chemistry through specific species that have large photodissociation cross sections at 1216 A. These include HCN, NH3 and CH4, for which the column densities are decreased by an order of magnitude or more due to the presence of Lyman alpha radiation in the UV spectrum. A few spe...

  11. The Non-Linear Power Spectrum of the Lyman Alpha Forest

    CERN Document Server

    Arinyo-i-Prats, Andreu; Viel, Matteo; Cen, Renyue

    2015-01-01

    The Lyman alpha forest power spectrum has been measured on large scales by the BOSS survey in SDSS-III at $z\\sim 2.3$, has been shown to agree well with linear theory predictions, and has provided the first measurement of Baryon Acoustic Oscillations at this redshift. However, the power at small scales, affected by non-linearities, has not been well examined so far. We present results from a variety of hydrodynamic simulations to predict the redshift space non-linear power spectrum of the Lyman Alpha transmission for several models, testing the dependence on resolution and box size. A new fitting formula is introduced to facilitate the comparison of our simulation results with observations and other simulations. The non-linear power spectrum has a generic shape determined by a transition scale from linear to non-linear anisotropy, and a Jeans scale below which the power drops rapidly. In addition, we predict the two linear bias factors of the Lyman Alpha forest and provide a better physical interpretation of ...

  12. Numerical Simulations of the Lyman-alpha forest - A comparison of Gadget-2 and Enzo

    CERN Document Server

    Regan, J A; Viel, M; Regan, John A.; Haehnelt, Martin G.

    2006-01-01

    We compare simulations of the Lyman-alpha forest performed with two different hydrodynamical codes, Gadget-2 and Enzo. A comparison of the dark matter power spectrum for simulations run with identical initial conditions show differences of 1-3% at the scales relevant for quantitative studies of the Lyman-alpha forest. This allows a meaningful comparison of the effect of the different implementations of the hydrodynamic part of the two codes. Using the same cooling and heating algorithm in both codes the differences in the temperature and the density probability distribution function are of the order of 10%. These differences can be mainly attributed to a slight mismatch in the resolution. The differences are smaller than or equal to the effects of boxsize and resolution on these statistics. Once resolution effects are taken into account the differences in the flux power spectrum - the statistics most widely used for estimating the matter power spectrum and cosmological parameters from Lyman-alpha forest data ...

  13. Spatial correlation between submillimetre and Lyman-alpha galaxies in the SSA 22 protocluster

    CERN Document Server

    Tamura, Yoichi; Nakanishi, Kouichiro; Hatsukade, Bunyo; Iono, Daisuke; Wilson, Grant W; Yun, Min S; Takata, Tadafumi; Matsuda, Yuichi; Tosaki, Tomoka; Ezawa, Hajime; Perera, Thushara A; Scott, Kimberly S; Austermann, Jason E; Hughes, David H; Aretxaga, Itziar; Chung, Aeree; Oshima, Tai; Yamaguchi, Nobuyuki; Tanaka, Kunihiko; Kawabe, Ryohei; 10.1038/nature07947

    2009-01-01

    Lyman-alpha emitters are thought to be young, low-mass galaxies with ages of ~10^8 yr. An overdensity of them in one region of the sky (the SSA 22 field) traces out a filamentary structure in the early Universe at a redshift of z = 3.1 (equivalent to 15 per cent of the age of the Universe) and is believed to mark a forming protocluster. Galaxies that are bright at (sub)millimetre wavelengths are undergoing violent episodes of star formation, and there is evidence that they are preferentially associated with high-redshift radio galaxies, so the question of whether they are also associated with the most significant large-scale structure growing at high redshift (as outlined by Lyman-alpha emitters) naturally arises. Here we report an imaging survey of 1,100-um emission in the SSA 22 region. We find an enhancement of submillimetre galaxies near the core of the protocluster, and a large-scale correlation between the submillimetre galaxies and the low-mass Lyman-alpha emitters, suggesting synchronous formation of ...

  14. Spatial correlation between submillimetre and Lyman-alpha galaxies in the SSA 22 protocluster.

    Science.gov (United States)

    Tamura, Yoichi; Kohno, Kotaro; Nakanishi, Kouichiro; Hatsukade, Bunyo; Iono, Daisuke; Wilson, Grant W; Yun, Min S; Takata, Tadafumi; Matsuda, Yuichi; Tosaki, Tomoka; Ezawa, Hajime; Perera, Thushara A; Scott, Kimberly S; Austermann, Jason E; Hughes, David H; Aretxaga, Itziar; Chung, Aeree; Oshima, Tai; Yamaguchi, Nobuyuki; Tanaka, Kunihiko; Kawabe, Ryohei

    2009-05-07

    Lyman-alpha emitters are thought to be young, low-mass galaxies with ages of approximately 10(8) yr (refs 1, 2). An overdensity of them in one region of the sky (the SSA 22 field) traces out a filamentary structure in the early Universe at a redshift of z approximately 3.1 (equivalent to 15 per cent of the age of the Universe) and is believed to mark a forming protocluster. Galaxies that are bright at (sub)millimetre wavelengths are undergoing violent episodes of star formation, and there is evidence that they are preferentially associated with high-redshift radio galaxies, so the question of whether they are also associated with the most significant large-scale structure growing at high redshift (as outlined by Lyman-alpha emitters) naturally arises. Here we report an imaging survey of 1,100-microm emission in the SSA 22 region. We find an enhancement of submillimetre galaxies near the core of the protocluster, and a large-scale correlation between the submillimetre galaxies and the low-mass Lyman-alpha emitters, suggesting synchronous formation of the two very different types of star-forming galaxy within the same structure at high redshift. These results are in general agreement with our understanding of the formation of cosmic structure.

  15. A systematic study of Lyman-Alpha transfer through outflowing shells: Model parameter estimation

    CERN Document Server

    Gronke, Max; Dijkstra, Mark

    2015-01-01

    Outflows promote the escape of Lyman-$\\alpha$ (Ly$\\alpha$) photons from dusty interstellar media. The process of radiative transfer through interstellar outflows is often modelled by a spherically symmetric, geometrically thin shell of gas that scatters photons emitted by a central Ly$\\alpha$ source. Despite its simplified geometry, this `shell model' has been surprisingly successful at reproducing observed Ly$\\alpha$ line shapes. In this paper we perform automated line fitting on a set of noisy simulated shell model spectra, in order to determine whether degeneracies exist between the different shell model parameters. While there are some significant degeneracies, we find that most parameters are accurately recovered, especially the HI column density ($N_{\\rm HI}$) and outflow velocity ($v_{\\rm exp}$). This work represents an important first step in determining how the shell model parameters relate to the actual physical properties of Ly$\\alpha$ sources. To aid further exploration of the parameter space, we ...

  16. How Lyman Alpha Emission Depends On Galaxy Stellar Mass

    CERN Document Server

    Oyarzún, Grecco A; González, Valentino; Mateo, Mario; Bailey, John I; Finkelstein, Steven L; Lira, Paulina; Crane, Jeffrey D; Olszewski, Edward W

    2016-01-01

    In this work, we show how the stellar mass (M) of galaxies affects the 3alpha equivalent width (EW) distribution. To this end, we design a sample of 629 galaxies in the M range 7.6 < logM/Msun < 10.6 from the 3D-HST/CANDELS survey. We perform spectroscopic observations of this sample using the Michigan/Magellan Fiber System, allowing us to measure Ly-alpha fluxes and use 3D-HST/CANDELS ancillary data. In order to study the Ly-alpha EW distribution dependence on M, we split the whole sample in three stellar mass bins. We find that, in all bins, the distribution is best represented by an exponential profile of the form dN(M)/dEW= A(M)exp(-EW/W0(M))/W0(M). Through a Bayesian analysis, we confirm that lower M galaxies have higher Ly-alpha EWs. We also find that the fraction A of galaxies featuring emission and the e-folding scale W0 of the distribution anti- correlate with M, recovering expressions of the forms A(M)= -0.26(.13) logM/Msun+3.01(1.2) and W0(M)= -15.6(3.5) logM/Msun +166(34). Th...

  17. The Reionization and Galaxy Evolution Probed by z=7 Lyman Alpha Emitters

    CERN Document Server

    Ota, Kazuaki; Kashikawa, Nobunari; Shimasaku, Kazuhiro; Kobayashi, Masakazu A R; Totani, Tomonori; Nagashima, Masahiro; Morokuma, Tomoki; Furusawa, Hisanori; Hattori, Takashi; Matsuda, Yuichi; Hashimoto, Tetsuya; Ouchi, Masami

    2007-01-01

    We made a narrowband NB973 (bandwidth of 200A at 9755A) imaging of the Subaru Deep Field (SDF) and found two z=7 Lyman alpha emitter (LAE) candidates down to NB973=24.9. Carrying out deep follow-up spectroscopy, we identified one of them as a real z=6.96 LAE. This has shown that galaxy formation was in progress just 750 Myr after the Big Bang. Meanwhile, the Lyman alpha line luminosity function of LAE is known to decline from z=5.7 to 6.6 in the SDF. L* at z=6.6 is 40-60% of that at z=5.7. We also confirm that the number density of z=7 LAE is only 17% of the density at z=6.6 comparing the latest SDF LAE samples. This series of significant decreases in LAE density with increasing redshift can be the result of galaxy evolution during these epochs. However, using the UV continuum luminosity functions of LAEs, those of Lyman break galaxies, and a LAE evolution model based on the hierarchical clustering, we find that galaxy evolution alone cannot explain all the decrease in density. This extra density deficit can ...

  18. The Lyman-alpha Reference Sample: I. Survey outline and first results for Markarian 259

    CERN Document Server

    Östlin, Göran; Duval, Florent; Sandberg, Andreas; Rivera-Thorsen, Thoger; Marquart, Thomas; Orlitova, Ivana; Adamo, Angela; Melinder, Jens; Guaita, Lucia; Atek, Hakim; Cannon, John M; Gruyters, Pieter; Herenz, Edmund Christian; Kunth, Daniel; Laursen, Peter; Mas-Hesse, J Miguel; Micheva, Genoveva; Pardy, Hector Oti-Floranes Stephen A; Roth, Martin M; Schaerer, Daniel; Verhamme, Anne

    2014-01-01

    The Lyman-alpha reference sample (LARS) is a program with the Hubble Space Telescope (HST) that provides a sample of local universe laboratory galaxies in which to study the astrophysics of the visibility and strength of the Lyman-alpha (Lya) line of hydrogen. This article presents an overview of the survey, its selection function and HST imaging observations. The sample was selected from the GALEX+SDSS catalogue at z=0.028-0.19, in order to allow Lya to be captured with combinations of long pass filters in the Solar Blind Channel (SBC) of HST/ACS. In addition, LARS utilises Halpha and Hbeta narrow, and U, B, i broad-band imaging with ACS and WFC3. In order to study galaxies in which large numbers of Lya photons are produced we demanded an Halpha equivalent width > 100{\\AA}. The sample of 14 galaxies covers far UV (FUV) luminosities that overlaps with those of high-z Lya emitters and Lyman Break Galaxies (LBGs). We present the reduction steps used to obtain the Lya images, including our LARS eXtraction softwa...

  19. Exploring the nature of the Lyman-$\\alpha$ emitter CR7

    CERN Document Server

    Hartwig, Tilman; Magg, Mattis; Bromm, Volker; Klessen, Ralf S; Glover, Simon C O; Whalen, Daniel J; Pellegrini, Eric W; Volonteri, Marta

    2015-01-01

    CR7 is the brightest Lyman-$\\alpha$ emitter observed at $z>6$, which shows very strong Lyman-$\\alpha$ and HeII 1640 \\AA\\ line luminosities, but no metal line emission. Previous studies suggest that CR7 hosts either young primordial stars with a total stellar mass of $\\sim 10^7\\,\\mathrm{M}_\\odot$ or a black hole of $\\sim 10^6\\,\\mathrm{M}_\\odot$. Here, we explore different formation scenarios for CR7 with a semianalytical model, based on the random sampling of dark matter merger trees. We find that primordial stars cannot account for the observed line luminosities because of their short lifetimes and because of early metal enrichment. Black holes that are the remnants of the first stars are either not massive enough, or reside in metal-polluted haloes, ruling out this possible explanation of CR7. Our models instead suggest that direct collapse black holes, which form in metal-free haloes exposed to large Lyman-Werner fluxes, are more likely the origin of CR7. However, this result is derived under optimistic ass...

  20. Limits on Lyman Continuum escape from z=2.2 H-alpha emitting galaxies

    CERN Document Server

    Sandberg, A; Melinder, J; Bik, A; Guaita, L

    2015-01-01

    The leakage of Lyman continuum photons from star forming galaxies is an elusive parameter. When observed, it provides a wealth of information on star formation in galaxies and the geometry of the interstellar medium, and puts constraints on the role of star forming galaxies in the reionization of the universe. H-alpha-selected galaxies at z~2 trace the highest star formation population at the peak of cosmic star formation history, providing a base for directly measuring Lyman continuum escape. Here we present this method, and highlight its benefits as well as caveats. We also use the method on 10 H-alpha emitters in the Chandra Deep Field South at z=2.2, also imaged with the Hubble Space Telescope in the ultraviolet. We find no individual Lyman continuum detections, and our stack puts a 5 sigma upper limit on the average absolute escape fraction of <24%, consistent with similar studies. With future planned observations, the sample sizes would rapidly increase and the method presented here would provide ver...

  1. The visibility of Lyman Alpha Emitters: constraining reionization, ionizing photons and dust

    CERN Document Server

    Hutter, A; Partl, A M; Müller, V

    2014-01-01

    We couple state of the art cosmological simulations (GADGET-2) with a dust model and a radiative transfer code (pCRASH) to build a complete model for high-redshift Lyman Alpha emitters (LAEs). Due to poor constraints available on the escape fraction of HI ionizing photons (f_esc) from galaxies, we use five different values f_esc=0.05,0.25,0.5,0.75,0.95 to post-process the cosmological simulation with pCRASH. Starting from a completely neutral Universe, we run pCRASH until reionization is complete, i.e. the average neutral hydrogen (HI) fraction drops to ~ 10^-4. For a given f_esc and combination, the only free-parameter left to match model results to observations is the relative escape of Lyman Alpha (Lya) and continuum photons from the galactic environment (f_\\alpha/f_c). Starting from a scenario wherein dust is homogeneously distributed (f_\\alpha/f_c ~ 0.68), we find that the observed LAE UV and Lya luminosity functions (LFs) jointly constrain f_esc ~ 0.05 and and f_\\alpha/f_c such that a decrease in th...

  2. Large Area Lyman Alpha Survey: Finding Young Galaxies at z=4.5

    Science.gov (United States)

    Malhotra, S.; Rhoads, J.; Dey, A.; Stern, D.; Spinrad, H.

    Strong Lyα emission is a signpost of young stars and the absence of dust and thus indicates young galaxies. To find such a population of young galaxies at z=4.5 we started the Large Area Lyman Alpha survey (LALA). This survey achieves an unprecedented combination of volume and sensitivity by using narrow-band filters on a large format (36' × 36') camera on the 4 meter telescope at KPNO. The volume density and star-formation contribution of the Lyα emitters at z=4.5 is comparable to that of Lyman break galaxies. With many candidates and a few spectroscopic confirmations in hand we discuss what the properties of Lyα emitters imply for galaxy and star formation in the early universe.

  3. Jovian Equatorial H Lyman-alpha and the Ionosphere

    Science.gov (United States)

    Ballester, Gilda E.

    An excess of H Ly alpha emission has been a persistent feature in Jupiter's equatorial upper atmosphere since its discovery in 1978. This Ly alpha 'bulge' was found by high-resolution IUE observations to be due to broadening of the Jovian line increasing the resonant scattering of the solar Ly alpha, rather than from a local enhancement in the H density. The line broadening implies that the H column at the bulge is disturbed by a localized, non-thermal process, and two mechanisms have been proposed to explain this: one by the generation of turbulence from strong thermospheric winds or jets meeting at the bulge region and originating in the active Jovian auroral zones, the other involving a superthermal population of H atoms produced by a process analogous to the equatorial anomaly and tropical arcs on the Earth. Some line broadening was also observed in the off-bulge region while modelling of the usual bulge profile does not predict this behavior, but these observations may have been performed at a time of an unusually large extension of the bulge. We propose to make a series of high-dispersion observations (of improved S/N) for a detailed longitudinal study of the line profile which would be of benefit independently of the particular bulge conditions (to be determined with low-dispersion exposures). In addition, new insight will be gained with simultaneous ground-based observations of the newly discovered global ionospheric H3+ emissions. These emissions are diagnostic of the ionospheric temperature and ion density, and have already shown very particular characteristics in the H Ly alpha bulge region. Coordinated observations of the whole longitudinal range should therefore set new constraints on the mechanisms operating in the Jovian equatorial upper atmosphere.

  4. The Lyman alpha reference sample. II. Hubble space telescope imaging results, integrated properties, and trends

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, Matthew; Östlin, Göran; Duval, Florent; Sandberg, Andreas; Guaita, Lucia; Melinder, Jens; Rivera-Thorsen, Thøger [Department of Astronomy, Oskar Klein Centre, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden); Adamo, Angela [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Schaerer, Daniel [Université de Toulouse, UPS-OMP, IRAP, F-31000 Toulouse (France); Verhamme, Anne; Orlitová, Ivana [Geneva Observatory, University of Geneva, 51 Chemin des Maillettes, CH-1290 Versoix (Switzerland); Mas-Hesse, J. Miguel; Otí-Floranes, Héctor [Centro de Astrobiología (CSIC-INTA), Departamento de Astrofísica, P.O. Box 78, E-28691 Villanueva de la Cañada (Spain); Cannon, John M.; Pardy, Stephen [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Atek, Hakim [Laboratoire dAstrophysique, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire, CH-1290 Sauverny (Switzerland); Kunth, Daniel [Institut d' Astrophysique de Paris, UMR 7095, CNRS and UPMC, 98 bis Bd Arago, F-75014 Paris (France); Laursen, Peter [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Herenz, E. Christian, E-mail: matthew@astro.su.se [Leibniz-Institut für Astrophysik (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)

    2014-02-10

    We report new results regarding the Lyα output of galaxies, derived from the Lyman Alpha Reference Sample, and focused on Hubble Space Telescope imaging. For 14 galaxies we present intensity images in Lyα, Hα, and UV, and maps of Hα/Hβ, Lyα equivalent width (EW), and Lyα/Hα. We present Lyα and UV radial light profiles and show they are well-fitted by Sérsic profiles, but Lyα profiles show indices systematically lower than those of the UV (n ≈ 1-2 instead of ≳ 4). This reveals a general lack of the central concentration in Lyα that is ubiquitous in the UV. Photometric growth curves increase more slowly for Lyα than the far ultraviolet, showing that small apertures may underestimate the EW. For most galaxies, however, flux and EW curves flatten by radii ≈10 kpc, suggesting that if placed at high-z only a few of our galaxies would suffer from large flux losses. We compute global properties of the sample in large apertures, and show total Lyα luminosities to be independent of all other quantities. Normalized Lyα throughput, however, shows significant correlations: escape is found to be higher in galaxies of lower star formation rate, dust content, mass, and nebular quantities that suggest harder ionizing continuum and lower metallicity. Six galaxies would be selected as high-z Lyα emitters, based upon their luminosity and EW. We discuss the results in the context of high-z Lyα and UV samples. A few galaxies have EWs above 50 Å, and one shows f{sub esc}{sup Lyα} of 80%; such objects have not previously been reported at low-z.

  5. The Lyman-$\\alpha$ emission in local Star-Forming Galaxies Scenario and Connection with Primeval Galaxies

    CERN Document Server

    Kunth, D; Terlevich, R J; Tenorio-Tagle, G

    1998-01-01

    We review the Lyan alpha emission in local star-forming galaxies. In most cases as already shown by the IUE, the emission is absent or much weaker than expected. This occurs because Lyman alpha photons can be resonantly scattered by the neutral gas and destroyed by even very low amounts of dust. However new Hubble Space Telescope observations (HST) indicate that other factors such as the velocity structure of the gas play a crucial role. Gas flows are likely to occur as powered by the kinetic energy released via stellar winds and supernova. We propose a scenario based on the hydrodynamics of superbubbles powered by massive bursts of star formation that naturally accounts for the variety of Lyman alpha line detections in star-forming galaxies. We caution with the attempts to derive the co-moving star formation rate at high redshift from Lyman alpha emission searches.

  6. The Gunn-Peterson effect and the Lyman $\\alpha$ forest

    CERN Document Server

    Levshakov, S A

    1997-01-01

    We show that spatial correlations in a stochastic large scale velocity field in an otherwise smooth intergalactic medium (homogeneous comoving density) superposed on the general Hubble flow, may cause a `line-like' structure in QSO spectra similar to the population of unsaturated Ly-alpha forest lines which usually are attributed to individual clouds with 10^{11} <= N(HI) <= 5*10^{13} cm^{-2}. Therefore there is no clear observational distinction between a diffuse intergalactic medium and discrete intergalactic clouds. It follows that the HI-density in the diffuse intergalactic medium might be substantially underestimated if it is determined from the observed intensity distribution near the apparent continuum in high resolution spectra of QSOs. Our tentative estimate implies a diffuse neutral hydrogen opacity tau_{GP} = 0.3 at z = 3 and a current baryon density Omega_{IGM} = 0.08$, assuming a Hubble constant H = 70 km s^{-1} Mpc^{-1}.

  7. Spectroscopy of 7 Radio-Loud QSOs at 2Lyman-alpha Nebulae Accreting onto Host Galaxies

    CERN Document Server

    Roche, Nathan; Binette, Luc

    2014-01-01

    We performed long-slit optical spectroscopy (GTC-OSIRIS) of 6 radio-loud QSOs at redshifts $2Lyman-$\\alpha$ emitting nebulae, and detect extended Lyman-$\\alpha$ emission for 4, with surface brightness $\\sim10^{-16}$ ergs $\\rm cm^{-2}s^{-1}arcsec^{-2}$ and line width FWHM 400-1100 (mean 863) km $\\rm s^{-1}$. We also observed the $z\\simeq 5.9$ radio-loud QSO, SDSS J2228+0110, and find evidence of a $\\geq 10$ kpc extended Lyman-$\\alpha$ emission nebula, a new discovery for this high-redshift object. Spatially-resolved kinematics of the 5 nebulae are examined by fitting the Lyman-$\\alpha$ wavelength at a series of positions along the slit. We found the line-of-sight velocity $\\Delta(v)$ profiles to be relatively flat. However, 3 of the nebulae appear systematically redshifted by 250-460 km $\\rm s^{-1}$ relative to the Lyman-$\\alpha$ line of the QSO (with no offset for the other two), which we argue is evidence for infall. One of these (Q0805+046) had a small ($...

  8. Revealing the z~2.5 Cosmic Web With 3D Lyman-Alpha Forest Tomography: A Deformation Tensor Approach

    CERN Document Server

    Lee, Khee-Gan

    2016-01-01

    Studies of cosmological objects should take into account their positions within the cosmic web of large-scale structure. Unfortunately, the cosmic web has only been extensively mapped at low-redshifts ($z1$, the required galaxy densities are inaccessible for the foreseeable future, but 3D reconstructions of Lyman-$\\alpha$ forest absorption in closely-separated background QSOs and star-forming galaxies already offer a detailed window into $z\\sim2-3$ large-scale structure. We quantify the utility of such maps for studying the cosmic web by using realistic $z=2.5$ Ly$\\alpha$ forest simulations matched to observational properties of upcoming surveys. A deformation tensor-based analysis is used to classify voids, sheets, filaments and nodes in the flux, which is compared to those determined from the underlying dark matter field. We find an extremely good correspondence, with $70\\%$ of the volume in the flux maps correctly classified relative to the dark matter web, and $99\\%$ classified to within 1 eigenvalue. Thi...

  9. A New Population of High Redshift, Dusty Lyman-Alpha Emitters and Blobs Discovered by WISE

    CERN Document Server

    Bridge, Carrie R; Borys, Colin J K; Petty, Sara; Benford, Dominic; Eisenhardt, Peter; Farrah, Duncan; Griffith, Roger L; Jarrett, Tom; Stanford, S Adam; Stern, Daniel; Tsai, Chao-Wei; Wright, Edward L; Wu, Jingwen

    2012-01-01

    We report a new technique to select 1.610^{13-14}L_sun) and warm colors, typically larger than submillimeter-selected galaxies (SMGs) and dust-obscured galaxies (DOGs). These traits are commonly associated with the dust being energized by intense AGN activity. We hypothesize that the combination of spatially extended Lyman-alpha, large amounts of warm IR-luminous dust, and rarity (implying a short-lived phase) can be explained if the galaxies are undergoing strong `feedback' transforming them from an extreme dusty starburst to a QSO.

  10. Abundances in Damped Lyman-$\\alpha$ Systems and Chemical Evolution of High Redshift Galaxies

    CERN Document Server

    Lü, L; Barlow, T A; Lu, Limin; Sargent, Wallace L.W.; Barlow, Thomas A.

    1997-01-01

    Recent abundance measurements in damped Lyman-alpha galaxies, supplemented with unpublished Keck observations, are discussed. The metallicity distribution with cosmic time is examined for clues about the degree of enrichment, the onset of initial star formation, and the nature of the galxies. The relative abundances of the elements are compared with the abundnce pattern in Galactic halo stars and in the Sun, taking into account of the effects of dust depletion, in order to gain insight into the stellar processes and the time scales by which the enrichment occurred.

  11. Three Lyman-alpha Emitters at z approx 6: Early GMOS/Gemini Data from the GLARE Project

    CERN Document Server

    Stanway, E R; Bunker, A J; Abraham, R G; Hook, I; Rhoads, J; McCarthy, P J; Boyle, B; Colless, M; Crampton, D; Couch, W; Jorgensen, I; Malhotra, S; Murowinski, R; Roth, K; Savaglio, S; Tsvetanov, Z I; Stanway, Elizabeth R.; Glazebrook, Karl; Bunker, Andrew J.; Abraham, Roberto G.; Hook, Isobel; Rhoads, James; Carthy, Patrick J. Mc; Boyle, Brian; Colless, Matthew; Crampton, David; Couch, Warrick; J{\\o}rgensen, Inger; Malhotra, Sangeeta; Murowinski, Rick; Roth, Kathy; Savaglio, Sandra; Tsvetanov., Zlatan

    2004-01-01

    We report spectroscopic detection of three z \\sim 6 Lyman-alpha emitting galaxies, in the vicinity of the Hubble Ultra Deep Field, from the early data of the Gemini Lyman-alpha at Reionisation Era (GLARE) project. Two objects, GLARE#3001 (z =5.79) and GLARE#3011 (z =5.94), are new detections and are fainter in z' (z'_AB = 26.37 and 27.15) than any continuum-selected objects previously detected in Lyman-alpha. A third object, GLARE#1042 (z =5.83) has previously been detected in line emission from the ground; we report here a new spectroscopic continuum detection. Gemini/GMOS-S spectra of these objects, obtained using nod & shuffle, are presented together with a discussion of their photometric properties. All three objects were selected for spectroscopy via the i-drop Lyman Break technique, the two new detections from the GOODS v1.0 imaging data. The red i'-z' colors and high equivalent widths of these objects suggest a high-confidence z>5 Lyman-alpha identification of the emission lines. This brings the to...

  12. The Contribution of HI-rich Galaxies to the Damped Lyman-alpha Absorber Population at z=0

    CERN Document Server

    Schneider, S E; Schneider, Jessica L. Rosenberg & Stephen E.

    2003-01-01

    We present a study of the expected properties of the low redshift damped Lyman-alpha absorber population determined from a sample of HI-selected galaxies in the local universe. We use measurements of the number density and HI cross-section of galaxies to show that the total HI cross-section at column densities sufficient to produce damped Lyman-alpha absorption is consistent with no evolution of the absorber population. We also find that the dN/dz distribution is dominated by galaxies with HI masses near 10^9 M_solar. However, because of the large dispersion in the correlation between HI mass and stellar luminosity, we find that the distribution of dN/dz as a function of L_J is nearly flat. Additionally, we demonstrate that the linewidths of the HI-selected galaxies are roughly consistent with the kinematics of damped Lyman-alpha absorbers.

  13. Lyman-alpha Blobs Like Company : The Discovery of A Candidate 100 kpc Lyman-alpha Blob Near to A Radio Galaxy with A Giant Lyman-alpha halo, B3 J2330+3927 at z=3.1

    CERN Document Server

    Matsuda, Y; Morimoto, N; Smail, Ian; De Breuck, C; Ohta, K; Kodama, T; Inoue, A K; Hayashino, T; Kousai, K; Nakamura, E; Horie, M; Yamada, T; Kitamura, M; Saitô, T; Taniguchi, Y; Tanaka, I; Hibon, P

    2009-01-01

    We present the discovery of a candidate of giant radio-quiet Lyman-alpha (Lya) blob (RQLAB) in a large-scale structure around a high-redshift radio galaxy (HzRG) lying in a giant Lya halo, B3 J2330+3927 at redshift z=3.087. We obtained Lya imaging around B3 J2330+3927 with Subaru/Suprime-Cam to search for Lya emitters (LAEs) and absorbers (LAAs) at redshift z=3.09+-0.03. We detected candidate 127 LAEs and 26 LAAs in the field of view of 31' x 24'. We found that B3 J2330+3927 is surrounded by a 130 kpc Lya halo and a large-scale (60 x 20 comoving Mpc) filamentary structure. The large-scale structure contains one prominent local density peak with an overdensity of greater than 5, which is 8' (15 comoving Mpc) away from B3 J2330+3927. In this peak, we discovered a candidate 100 kpc RQLAB. The existence of both types of Lya nebulae in the same large-scale structure suggests that giant Lya nebulae need special large-scale environments to form. On smaller scales, however, the location of B3 J2330+3927 is not a sign...

  14. Lyman alpha emission from the first galaxies: implications of UV backgrounds and the formation of molecules : implications of UV backgrounds and the formation of molecules

    NARCIS (Netherlands)

    Latif, M. A.; Schleicher, D. R. G.; Spaans, M.; Zaroubi, S.

    The Lyman alpha line is a robust tracer of high redshift galaxies. We present estimates of Lyman alpha emission from a protogalactic halo illuminated by UV background radiation fields with various intensities. For this purpose, we performed cosmological hydrodynamics simulations with the adaptive

  15. Lyman-alpha observations of comets West 1976 VI and P d'Arrest 1976 XI with Copernicus

    Science.gov (United States)

    Festou, M. C.; Keller, H. U.; Bertaux, J. L.; Barker, E. S.

    1983-02-01

    Lyman-alpha observations by the Copernicus satellite have been used to determine the production rates of hydrogen atoms of comets West 1976 VI and P/d'Arrest 1976 XI at a time when they were dynamically active (splitting or outburst of the nucleus). The observed Lyman-alpha line widths are in agreement with those observed in comet Kobayashi-Berger-Milon 1975 IX and, consequently, do not contradict the assumption that the H atoms are produced by the photodissociation of water vapor, even in CO(plus) rich comets..

  16. Lenses in the forest: cross--correlation of the Lyman-alpha flux with CMB lensing

    Energy Technology Data Exchange (ETDEWEB)

    Vallinotto, Alberto; /Paris, Inst. Astrophys. /Fermilab; Das, Sudeep; /Princeton U. Observ. /Princeton U.; Spergel, David N.; /Princeton U. Observ. /APC, Paris; Viel, Matteo; /Trieste Observ. /INFN, Trieste

    2009-03-01

    We present a theoretical estimate for a new observable: the cross-correlation between the Lyman-{alpha}-flux fluctuations in quasar (QSO) spectra and the convergence of the cosmic microwave background (CMB) as measured along the same line-of-sight. As a first step toward the assessment of its detectability, we estimate the signal-to-noise ratio using linear theory. Although the signal-to-noise is small for a single line-of-sight and peaks at somewhat smaller redshifts than those probed by the Lyman-{alpha} forest, we estimate a total signal-to-noise of 9 for cross-correlating QSO spectra of SDSSIII with Planck and 20 for cross-correlating with a future polarization based CMB experiment. The detection of this effect would be a direct measure of the neutral hydrogen-matter cross-correlation and could provide important information on the growth of structures at large scales in a redshift range which is still poorly probed by observations.

  17. Probing the Physical Properties of z=4.5 Lyman Alpha Emitters with Spitzer

    CERN Document Server

    Finkelstein, Keely D; Tilvi, Vithal; Malhotra, Sangeeta; Rhoads, James E; Grogin, Norman A; Pirzkal, Norbert; Dey, Arjun; Jannuzi, Buell T; Mobasher, Bahram; Pakzad, Sabrina; Salmon, Brett; Wang, Junzian

    2015-01-01

    We present the results from a stellar population modeling analysis of a sample of 162 z=4.5, and 14 z=5.7 Lyman alpha emitting galaxies (LAEs) in the Bootes field, using deep Spitzer/IRAC data at 3.6 and 4.5 um from the Spitzer Lyman Alpha Survey, along with Hubble Space Telescope NICMOS and WFC3 imaging at 1.1 and 1.6 um for a subset of the LAEs. This represents one of the largest samples of high-redshift LAEs imaged with Spitzer IRAC. We find that 30/162 (19%) of the z=4.5 LAEs and 9/14 (64%) of the z=5.7 LAEs are detected at >3-sigma in at least one IRAC band. Individual z=4.5 IRAC-detected LAEs have a large range of stellar mass, from 5x10^8 to 10^11 Msol. One-third of the IRAC-detected LAEs have older stellar population ages of 100 Myr - 1 Gyr, while the remainder have ages < 100 Myr. A stacking analysis of IRAC-undetected LAEs shows this population to be primarily low mass (8 -- 20 x 10^8 Msol) and young (64 - 570 Myr). We find a correlation between stellar mass and the dust-corrected ultraviolet-bas...

  18. The impact of feedback from galaxy formation on the Lyman-alpha transmitted flux

    CERN Document Server

    Viel, Matteo; Booth, Craig M

    2012-01-01

    The forest of Lyman-alpha absorption lines seen in the spectra of distant quasars has become an important probe of the distribution of matter in the Universe. We use large, hydrodynamical simulations from the OWLS project to investigate the effect of feedback from galaxy formation on the probability distribution function and the power spectrum of the Lyman-alpha transmitted flux. While metal-line cooling is unimportant, both galactic outflows from massive galaxies driven by active galactic nuclei and winds from low-mass galaxies driven by supernovae have a substantial impact on the flux statistics. At redshift z=2.25, the effects on the flux statistics are of a similar magnitude as the statistical uncertainties of published data sets. The changes in the flux statistics are not due to differences in the temperature-density relation of the photo-ionised gas. Instead, they are caused by changes in the density distribution and in the fraction of hot, collisionally ionised gas. It may be possible to disentangle as...

  19. Absorption signatures of warm-hot gas at low redshift: Broad Lyman-Alpha Absorbers

    CERN Document Server

    Tepper-García, Thorsten; Schaye, Joop; Booth, Craig M; Vecchia, Claudio Dalla; Theuns, Tom

    2012-01-01

    We investigate the physical state of HI absorbing gas at low redshift (z=0.25) using a subset of cosmological, hydrodynamic simulations from the OWLS project, focusing in particular on broad (b_HI > 40 km/s) Lyman-Alpha absorbers (BLAs), which are believed to originate in shock-heated gas in the Warm-Hot Intergalactic Medium (WHIM). Our fiducial model, which includes radiative cooling by heavy elements and feedback by supernovae and active galactic nuclei, predicts that by z=0.25 nearly 60 per cent of the gas mass ends up at densities and temperatures characteristic of the WHIM and we find that half of this fraction is due to outflows. The standard HI observables (distribution of HI column densities N_HI, distribution of Doppler parameters b_HI, b_HI - N_HI correlation) and the BLA line number density predicted by our simulations are in remarkably good agreement with observations. BLAs arise in gas that is hotter, more highly ionised and more enriched than the gas giving rise to typical Lyman-Alpha forest abs...

  20. Performance Characterization of the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) CCD Cameras

    Science.gov (United States)

    Joiner, Reyann; Kobayashi, Ken; Winebarger, Amy; Champey, Patrick

    2014-01-01

    The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding rocket instrument currently being developed by NASA's Marshall Space Flight Center (MSFC), the National Astronomical Observatory of Japan (NAOJ), and other partners. The goal of this instrument is to observe and detect the Hanle effect in the scattered Lyman-Alpha UV (121.6nm) light emitted by the Sun's chromosphere. The polarized spectrum imaged by the CCD cameras will capture information about the local magnetic field, allowing for measurements of magnetic strength and structure. In order to make accurate measurements of this effect, the performance characteristics of the three on- board charge-coupled devices (CCDs) must meet certain requirements. These characteristics include: quantum efficiency, gain, dark current, read noise, and linearity. Each of these must meet predetermined requirements in order to achieve satisfactory performance for the mission. The cameras must be able to operate with a gain of 2.0+/- 0.5 e--/DN, a read noise level less than 25e-, a dark current level which is less than 10e-/pixel/s, and a residual non- linearity of less than 1%. Determining these characteristics involves performing a series of tests with each of the cameras in a high vacuum environment. Here we present the methods and results of each of these performance tests for the CLASP flight cameras.

  1. Lyman-alpha constraints on warm and on warm-plus-cold dark matter models

    CERN Document Server

    Boyarsky, Alexey; Ruchayskiy, Oleg; Viel, Matteo

    2009-01-01

    We revisit Lyman-alpha bounds on the dark matter mass in Lambda Warm Dark Matter (Lambda-WDM) models, and derive new bounds in the case of mixed Cold plus Warm models (Lambda-CWDM), using a set up which is a good approximation for several theoretically well-motivated dark matter models. We combine WMAP5 results with two different Lyman-alpha data sets, including observations from the Sloan Digital Sky Survey. We pay a special attention to systematics, test various possible sources of error, and compare the results of different statistical approaches. Expressed in terms of the mass of a non-resonantly produced sterile neutrino, our bounds read m_NRP > 8 keV (frequentist 99.7% confidence limit) or m_NRP > 12.1 keV (Bayesian 95% credible interval) in the pure Lambda-WDM limit. For the mixed model, we obtain limits on the mass as a function of the warm dark matter fraction F_WDM. Within the mass range studied here (5 keV < m_NRP < infinity), we find that any mass value is allowed when F_WDM < 0.6 (freque...

  2. A Multiply-Imaged z $\\sim$ 6.3 Lyman Alpha Emitter candidate behind Abell 2261

    CERN Document Server

    Rydberg, Claes-Erik; Zackrisson, Erik; Melinder, Jens; Whalen, Daniel J; Klessen, Ralf S; Gonzalez, Juan; Östlin, Göran; Carollo, Daniela

    2016-01-01

    While the Lyman-$\\alpha$ ($\\mathrm{Ly}\\alpha$) emission line serves as an important tool in the study of galaxies at $z\\lesssim 6$, finding Ly$\\alpha$ emitters (LAE) at significantly higher redshifts has been more challenging, probably because of the increasing neutrality of the intergalactic medium above $z\\sim6$. Galaxies with extremely high rest-frame Ly$\\alpha$ equivalent widths, EW(Ly$\\alpha$) $\\gtrsim 150$ \\AA{}, at $z>6$ are good candidates for Ly$\\alpha$ follow-up observations, and can stand out in multiband imaging surveys because of their unusual colors. We have conducted a photometric search for such objects in the Cluster Lensing And Supernova survey with Hubble (CLASH), and report here the identification of three likely gravitationally-lensed images of a single LAE candidate at $z\\sim6.3$, behind the galaxy cluster Abell 2261($z = 0.225$). In the process, we also measured with Keck/MOSFIRE the first spectroscopic redshift of a multiply-imaged galaxy behind Abell 2261, at $z = 3.337$. This allows ...

  3. The Temporal Behaviour of Lyman-alpha Emission During Solar Flares From SDO/EVE

    CERN Document Server

    Milligan, Ryan O

    2015-01-01

    Despite being the most prominent emission line in the solar spectrum, there has been a notable lack of studies devoted to variations in Lyman-alpha (Ly$\\alpha$) emission during solar flares in recent years. The few examples that do exist, however, have shown Ly$\\alpha$ emission to be a substantial radiator of the total energy budget of solar flares (on the order of 10%). It is also a known driver of fluctuations in earth's ionosphere. The EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory now provides broadband, photometric Ly$\\alpha$ data at 10 s cadence, and has observed scores of solar flares in the 5 years since it was launched. However, the time profiles appear to display a rise time of tens of minutes around the time of the flare onset. This is in stark contrast to the rapid, impulsive increase observed in other intrinsically chromospheric features (H$\\alpha$, Ly$\\beta$, LyC, C III, etc.). Furthermore, the Ly$\\alpha$ emission peaks around the time of the peak of thermal soft X-ray e...

  4. About AGN ionization echoes, thermal echoes, and ionization deficits in low redshift Lyman-alpha blobs

    CERN Document Server

    Schirmer, Mischa; Levenson, Nancy A; Fu, Hai; Davies, Rebecca L; Keel, William C; Torrey, Paul; Bennert, Vardha N; Pancoast, Anna; Turner, James E H

    2016-01-01

    We report the discovery of 14 Lyman-alpha blobs (LABs) at z~0.3, existing at least 4-7 billion years later in the Universe than all other LABs known. Their optical diameters are 20-70 kpc, and GALEX data imply Ly-alpha luminosities of (0.4-6.3)x10^43 erg/s. Contrary to high-z LABs, they live in low-density areas. They are ionized by AGN, suggesting that cold accretion streams as a power source must deplete between z=2 and z=0.3. We also show that transient AGN naturally explain the ionization deficits observed in many LABs: Their Ly-alpha and X-ray fluxes decorrelate below 10^6 years because of the delayed escape of resonantly scattering Ly-alpha photons. High Ly-alpha luminosities do not require currently powerful AGN, independent of obscuration. Chandra X-ray data reveal intrinsically weak AGN, confirming the luminous optical nebulae as impressive ionization echoes. For the first time, we also report mid-infrared thermal echoes from the dusty tori. We conclude that the AGN have faded by 3-4 orders of magnit...

  5. From Mirrors to Windows: Lyman-Alpha Radiative Transfer in a Very Clumpy Medium

    CERN Document Server

    Gronke, Max; McCourt, Michael; Oh, S Peng

    2016-01-01

    Lyman-Alpha (Ly$\\alpha$) is the strongest emission line in the Universe and is frequently used to detect and study the most distant galaxies. Because Lya is a resonant line, photons typically scatter prior to escaping; this scattering process complicates the interpretation of Ly$\\alpha$ spectra, but also encodes a wealth of information about the structure and kinematics of neutral gas in the galaxy. Modeling the Ly$\\alpha$ line therefore allows us to study tiny-scale features of the gas, even in the most distant galaxies. Curiously, observed Ly$\\alpha$ spectra can be modeled successfully with very simple, homogeneous geometries (such as an expanding, spherical shell), whereas more realistic, multiphase geometries often fail to reproduce the observed spectra. This seems paradoxical since the gas in galaxies is known to be multiphase. In this Letter, we show that spectra emerging from extremely clumpy geometries with many clouds along the line of sight converge to the predictions from simplified, homogeneous mo...

  6. Trident: A three-pronged galaxy survey. I. Lyman alpha emitting galaxies at z~2 in GOODS North

    CERN Document Server

    Sandberg, A; Östlin, G; Hayes, M; Kiaeerad, F

    2015-01-01

    Context. Lyman alpha emitting galaxies (LAEs) are used to probe the distant universe and are therefore important for galaxy evolution studies and for providing clues to the nature of the epoch of reionization, but the exact circumstances under which Lyman alpha escapes a galaxy are still not fully understood. Aims. The Trident project is designed to simultaneously examine Lyman alpha, H-alpha and Lyman Continuum emission from galaxies at redshift z~2, thus linking together these three aspects of ionising radiation in galaxies. In this paper, we outline the strategy of this project and examine the properties of LAEs in the GOODS North field. Methods. We performed a narrowband LAE survey in GOODS North using existing and two custom made filters at the Nordic Optical Telescope with MOSCA. We use complementary broad band archival data in the field to make a careful candidate selection and perform optical to near-IR SED fitting. We also estimate far-infrared luminosities by matching our candidates to detections in...

  7. Adaptive Optics Imaging of Low-redshift Damped Lyman-alpha Quasar Absorbers

    CERN Document Server

    Chun, M R; Kulkarni, V P; Takamiya, M; Chun, Mark R.; Gharanfoli, Soheila; Kulkarni, Varsha P.; Takamiya, Marianne

    2005-01-01

    We have carried out a high angular resolution near-infrared imaging study of the fields of 6 quasars with 7 strong absorption line systems at z < 0.5, using the Hokupa'a adaptive optics system and the QUIRC near-infrared camera on the Gemini-North telescope. These absorption systems include 4 classical damped Lyman-alpha absorbers (DLAs), 2 sub-DLAs, and one Lyman-limit system. Images were obtained in the H or K' filters with FWHM between 0.2"-0.5" with the goal of detecting the absorbing galaxies and identifying their morphologies. Features are seen at projected separations of 0.5"-16.0" from the quasars and all of the fields show features at less than 2" separation. We find candidate absorbers in all of the seven systems. With the assumption that some of these are associated with the absorbers, the absorbers are low luminosity < 0.1 L*_H or L*_K; we do not find any large bright candidate absorbers in any of our fields. Some fields show compact features that are too faint for quantitative morphology, b...

  8. The primordial deuterium abundance of the most metal-poor damped Lyman-alpha system

    CERN Document Server

    Cooke, Ryan; Nollett, Kenneth M; Jorgenson, Regina

    2016-01-01

    We report the discovery and analysis of the most metal-poor damped Lyman-alpha (DLA) system currently known, which also displays the Lyman series absorption lines of neutral deuterium. The average [O/H] abundance of this system is [O/H] = -2.804 +/- 0.015, which includes an absorption component with [O/H] = -3.07 +/- 0.03. Despite the unfortunate blending of many weak D I absorption lines, we report a precise measurement of the deuterium abundance of this system. Using the six highest quality and self-consistently analyzed measures of D/H in DLAs, we report tentative evidence for a subtle decrease of D/H with increasing metallicity. This trend must be confirmed with future high precision D/H measurements spanning a range of metallicity. A weighted mean of these six independent measures provides our best estimate of the primordial abundance of deuterium, 10^5 (D/H)_P = 2.547 +/- 0.033 (log_10 (D/H)_P = -4.5940 +/- 0.0056). We perform a series of detailed Monte Carlo calculations of Big Bang nucleosynthesis (BB...

  9. No overdensity of Lyman Alpha Emitting Galaxies around a quasar at z~5.7

    CERN Document Server

    Mazzucchelli, C; Decarli, R; Farina, E P; Venemans, B P; Walter, F; Overzier, R

    2016-01-01

    Bright quasars, observed when the Universe was less than one billion years old (z>5.5), are known to host massive black holes (~10$^{9}$ M$_{\\odot}$), and are thought to reside in the center of massive dark matter overdensities. In this picture, overdensities of galaxies are expected around high redshift quasars. However, observations based on the detection of Lyman Break Galaxies (LBGs) around these quasars do not offer a clear picture: this may be due to the uncertain redshift constraints of LBGs, which are selected through broad-band filters only. To circumvent such uncertainties, we here perform a search for Lyman Alpha Emitting galaxies (LAEs) in the field of the quasar PSO J215.1512-16.0417 at z~5.73, through narrow band, deep imaging with FORS2 at the VLT. We study an area of 37 arcmin$^{2}$, i.e. ~206 comoving Mpc$^{2}$ at the redshift of the quasar. We find no evidence for an overdensity of LAEs in the quasar field with respect to blank field studies. Possible explanations for these findings include ...

  10. Detection of HI in Emission in the Lyman Alpha Emitting Galaxy Haro 11

    CERN Document Server

    Pardy, Stephen A; Östlin, Göran; Hayes, Matthew; Bergvall, Nils

    2016-01-01

    We present the first robust detection of HI 21 cm emission in the blue compact galaxy Haro 11 using the 100m Robert C. Byrd Green Bank Telescope (GBT). Haro 11 is a luminous blue compact galaxy with emission in both Lyman Alpha and the Lyman continuum. We detect (5.1 $\\pm$ 0.7 $\\times$10$^8$) M$_{\\odot}$ of HI gas at an assumed distance of 88 Mpc, making this galaxy HI deficient compared to other local galaxies with similar optical properties. Given this small HI mass, Haro 11 has an elevated M$_{H2}$/M$_{HI}$ ratio and a very low gas fraction compared to most local galaxies, and contains twice as much mass in ionized hydrogen as in neutral hydrogen. The HI emission has a linewidth of 71 kms$^{-1}$ and is offset 60 kms$^{-1}$ redward of the optical line center. It is undergoing a starburst after a recent merger which has elevated the star formation rate, and will deplete the gas supply in $<$ 0.2 Gyr. Although this starburst has elevated the SFR compared to galaxies with similar HI masses and linewidths, H...

  11. Resolution of the discrepancy between Balmer alpha emission rates, the solar Lyman beta flux, and models of geocoronal hydrogen concentration

    Science.gov (United States)

    Levasseur, A.-C.; Meier, R. R.; Tinsley, B. A.

    1976-01-01

    New satellite Balmer alpha measurements and solar Lyman beta flux and line profile measurements, together with new measurements of the zodiacal light intensity used in correcting both ground and satellite Balmer alpha measurements for the effects of the Fraunhofer line in the zodiacal light, have been used in a reevaluation of the long-standing discrepancy between ground-based Balmer alpha emission rates and other geocoronal hydrogen parameters. The solar Lyman beta line center flux is found to be (4.1 plus or minus 1.3) billion photons per sq cm per sec per angstrom at S(10.7) equals 110 and, together with a current hydrogen model which has 92,000 atoms per cu cm at 650 km for T(inf) equals 950 K, gives good agreement between calculated Balmer alpha emission rates and the ground-based and satellite measurements.

  12. High redshift galaxies and the Lyman-alpha forest in a CDM universe

    CERN Document Server

    Croft, R A C; Springel, V; Westover, M; White, M; Croft, Rupert A.C.; Hernquist, Lars; Springel, Volker; Westover, Michael; White, Martin

    2002-01-01

    We use a cosmological hydrodynamic simulation of a cold dark matter universe to investigate theoretically the relationship between high redshift galaxies and the Lyman=alpha forest at redshift z=3. Galaxies in the simulation are surrounded by halos of hot gas, which nevertheless contain enough neutral hydrogen to cause a Ly-alpha flux decrement, its strength increasing with galaxy mass. A comparison with recent observational data by Adelberger et. al on the Ly-alpha forest around galaxies reveals that actual galaxies may have systematically less Ly-alpha absorption within 1 Mpc of them than our simulated galaxies. In order to investigate this possibility, we add several simple prescriptions for galaxy feedback on the IGM to the evolved simulation. These include the effect of photoionizing background radiation coming from galactic sources, galactic winds whose only effect is to deposit thermal energy into the IGM, and another, kinetic model for winds, which are assumed to evacuate cavities in the IGM around ga...

  13. First results from Faint Infrared Grism Survey (FIGS): first simultaneous detection of Lyman-{\\alpha} emission and Lyman break from a galaxy at z=7.51

    CERN Document Server

    Tilvi, V; Malhotra, S; Finkelstein, S L; Rhoads, J E; Windhorst, R; Grogin, N A; Koekemoer, A; Zakamska, N; Ryan, R; Christensen, L; Hathi, N; Pharo, J; Joshi, B; Yang, H; Gronwall, C; Cimatti, A; Walsh, J; OConnell, R; Straughn, A; Ostlin, G; Rothberg, B; Livermore, R C; Hibon, P; Gardner, Jonathan P

    2016-01-01

    Galaxies at high redshifts provide a valuable tool to study cosmic dawn, and therefore it is crucial to reliably identify these galaxies. Here, we present an unambiguous and first simultaneous detection of both the Lyman-\\alpha emission and the Lyman break from a z = 7.512+/- 0.004 galaxy, observed in the Faint Infrared Grism Survey (FIGS). These spectra, taken with G102 grism on Hubble Space Telescope (HST), show a significant emission line detection (6{\\sigma}) in multiple observational position angles (PA), with total integrated Ly{\\alpha} line flux of 1.06+/- 0.12 e10-17erg s-1cm-2. The line flux is nearly a factor of four higher than the previous MOSFIRE spectroscopic observations of faint Ly{\\alpha} emission at {\\lambda} = 1.0347{\\mu}m, yielding z = 7.5078+/- 0.0004. This is consistent with other recent observations implying that ground-based near-infrared spectroscopy underestimates total emission line fluxes, and if confirmed, can have strong implications for reionization studies that are based on gro...

  14. Constraints on ionising photon production from the large-scale Lyman-alpha forest

    CERN Document Server

    Pontzen, Andrew; Peiris, Hiranya; Verde, Licia

    2014-01-01

    Recent work has shown that the z~2.5 Lyman-alpha forest on large scales encodes information about the galaxy and quasar populations that keep the intergalactic medium photoionized. We present the first forecasts for constraining the populations with data from current and next-generation surveys. At a minimum the forest should tell us whether galaxies or, conversely, quasars dominate the photon production. The number density and clustering strength of the ionising sources might be estimated to sub-10% precision with a DESI-like survey if degeneracies (e.g., with the photon mean-free-path, small-scale clustering power normalization and potentially other astrophysical effects) can be broken by prior information. We demonstrate that, when inhomogeneous ionisation is correctly handled, constraints on dark energy do not degrade.

  15. Investigating the Metallicity Evolution of Sub-damped Lyman alpha Systems

    Science.gov (United States)

    Konchady, Tarini; Jorgenson, Regina

    2017-01-01

    A clear understanding of the production and build up of metals across cosmic time is a key ingredient to any theory of galaxy formation and evolution. We present chemical abundance measurements for a sample of ~20 sub-damped Lyman alpha systems (subDLAs) detected in the absorption spectra of high redshift quasars taken by the Echellette Spectrograph and Imager (ESI) on the Keck II telescope. The sample contains absorbers with neutral hydrogen column densities of 1019.0 Metal line column densities were measured using the apparent optical depth method while neutral hydrogen column densities were measured via Voigt profile fitting. We compare our measurements to those of DLAs and subDLAs from the literature to investigate the potential differences in metallicity evolution between these types of galaxies.

  16. Diagnostics of MCF plasmas using Lyman-{alpha} fluorescence excited by one or two photons

    Energy Technology Data Exchange (ETDEWEB)

    Voslamber, D

    1998-11-01

    Laser-induced Lyman-{alpha} fluorescence of the hydrogen isotopes is investigated with regard to diagnostic applications in magnetically confined fusion plasmas. A formal analysis is presented for two excitation schemes: one-photon and Doppler-free two-photon excitation. The analysis includes estimates of the expected experimental errors arising from the photon noise and from the sensitivity of the observed fluorescence signals to variations of the plasma and laser parameters. Both excitation schemes are suitable primarily for application in the plasma edge, but even in the plasma bulk of large machines they can still be applied in combination with a diagnostic neutral beam. The two-photon excitation scheme is particularly attractive because it involves absorption spectra that are resolved within the Doppler width. This implies a large diagnostic potential and in particular offers a way to measure the deuterium-tritium fuel mix in fusion reactors. (author) 37 refs.

  17. Statistical properties of damped Lyman-alpha systems from Sloan Digital Sky Survey DR12

    CERN Document Server

    Bird, Simeon; Ho, Shirley

    2016-01-01

    We present new estimates for the statistical properties of damped Lyman-$\\alpha$ absorbers (DLAs). We compute the column density distribution function at $z>2$, the line density, $\\mathrm{d}N/\\mathrm{d}X$, and the neutral hydrogen density, $\\Omega_\\mathrm{DLA}$. Our estimates are derived from the DLA catalogue of \\cite{Garnett:2016}, which uses the SDSS--III DR12 quasar spectroscopic survey. This catalogue provides a probability that a given spectrum contains a DLA, allowing us to use even the noisiest data without biasing our results and thus substantially increase our sample size. We measure a non-zero column density distribution function at $95\\%$ confidence for all column densities $N_\\mathrm{HI} 4$. We show that our results are insensitive to the signal-to-noise ratio of the spectra, but that there is a residual dependence on quasar redshift for $z<2.5$, which may be due to remaining systematics in our analysis.

  18. A metallicity-spin temperature relation in damped Lyman-$\\alpha$ systems

    CERN Document Server

    Kanekar, Nissim; Briggs, Frank H; Chengalur, Jayaram N

    2009-01-01

    We report evidence for an anti-correlation between spin temperature $T_s$ and metallicity [Z/H], detected at $3.6 \\sigma$ significance in a sample of 26 damped Lyman-$\\alpha$ absorbers (DLAs) at redshifts $0.09 1.7$ have low metallicities, [Z/H] $< -1$, implying that the HI in high-$z$ DLAs is predominantly warm. The anti-correlation between $T_s$ and [Z/H] is consistent with the presence of a mass-metallicity relation in DLAs, suggested by the tight correlation between DLA metallicity and the kinematic widths of metal lines. Most high-$z$ DLAs are likely to arise in galaxies with low masses ($M_{\\rm vir} < 10^{10.5} M_\\odot$), low metallicities ([Z/H]$< -1$, and low cold gas fractions.

  19. The spin temperature of high-redshift damped Lyman-$\\alpha$ systems

    CERN Document Server

    Kanekar, N; Smette, A; Ellison, S L; Ryan-Weber, E V; Momjian, E; Briggs, F H; Lane, W M; Chengalur, J N; Delafosse, T; Grave, J; Jacobsen, D; de Bruyn, A G

    2013-01-01

    We report results from a programme aimed at investigating the temperature of neutral gas in high-redshift damped Lyman-$\\alpha$ absorbers (DLAs). This involved (1) HI 21cm absorption studies of a large DLA sample, (2) VLBI studies to measure the low-frequency quasar core fractions, and (3) optical/ultraviolet spectroscopy to determine DLA metallicities and velocity widths. Including literature data, our sample consists of 37 DLAs with estimates of the spin temperature $T_s$ and the covering factor. We find a strong $4\\sigma$) difference between the $T_s$ distributions in high-z (z>2.4) and low-z (z1 sub-sample. Since z>1 DLAs have angular diameter distances comparable to or larger than those of the background quasars, they have similar efficiency in covering the quasars. Low covering factors in high-z DLAs thus cannot account for the observed redshift evolution in spin temperatures. (Abstract abridged.)

  20. Cosmochemistry, cosmology and fundamental constants: High-resolution spectroscopy of damped Lyman-alpha systems

    CERN Document Server

    Quast, R; Smette, A; Garcet, O; Ledoux, C; López, S; Wisotzki, L

    2004-01-01

    Spectroscopy of QSO absorption lines provides essential observational input for the study of nucleosynthesis and chemical evolution of galaxies at high redshift. But new observations may indicate that present chemical abundance data are biased due to deficient spectral resolution and unknown selection effects: Recent high-resolution spectra reveal the hitherto unperceived chemical nonuniformity of molecular hydrogen-bearing damped Lyman-alpha (DLA) systems, and the novel H/ESO DLA survey produces compelling evidence for faint QSOs being attenuated by dust. We present a revised analysis of the molecular hydrogen-bearing DLA complex toward HE 0515-4414 showing nonuniform differential depletion of chemical elements onto dust grains, and introduce to the H/ESO DLA survey and its implications. Conclusively, we aim at starting an unbiased chemical abundance database established on high-resolution spectroscopic observations. New data to probe the temperature-redshift relation predicted by standard cosmology and to t...

  1. The Lyman-alpha forest in a blazar-heated Universe

    CERN Document Server

    Puchwein, Ewald; Springel, Volker; Broderick, Avery E; Chang, Philip

    2011-01-01

    It has been realised only recently that TeV emission from blazars can significantly heat the intergalactic medium (IGM) by pair-producing high-energy electrons and positrons, which in turn excite vigorous plasma instabilities, leading to a local dissipation of the pairs' kinetic energy. In this work, we use cosmological hydrodynamical simulations to model the impact of this induced blazar heating on the Lyman-alpha forest at intermediate redshifts (z~2-3). We find that blazar heating produces an inverted equation-of-state in the IGM and naturally resolves many of the problems present in previous simulations of the forest that included photoionisation heating alone. In particular, our simulation results simultaneously reproduce the observed effective optical depth and temperature as a function of redshift, the observed probability distribution functions (PDFs) of the transmitted flux, and the observed flux power spectra, over the full redshift range 2

  2. The BOSS Lyman-alpha Forest Sample from SDSS Data Release 9

    CERN Document Server

    Lee, Khee-Gan; Bartsch, Leslie E; Carithers, William; Dawson, Kyle S; Kirkby, David; Lundgren, Britt; Margala, Daniel; Palanque-Delabrouille, Nathalie; Pieri, Matthew M; Schlegel, David J; Weinberg, David H; Yeche, Christophe; Aubourg, Eric; Bautista, Julian; Bizyaev, Dmitry; Blomquist, Michael; Bolton, Adam S; Borde, Arnaud; Brewington, Howard; Busca, Nicolas G; Croft, Rupert A C; Delubac, Timothee; Ebelke, Garrett; Eisenstein, Daniel J; Font-Ribera, Andreu; Ge, Jian; Hamilton, Jean-Christophe; Hennawi, Joseph F; Ho, Shirley; Honscheid, Klaus; Goff, Jean-Marc Le; Malanushenko, Elena; Malanushenko, Viktor; Miralda-Escude, Jordi; Myers, Adam D; Noterdaeme, Pasquier; Oravetz, Daniel; Pan, Kaike; Paris, Isabelle; Petitjean, Patrick; Rich, James; Rollinde, Emmanuel; Ross, Nicholas P; Rossi, Graziano; Schneider, Donald P; Simmons, Audrey; Snedden, Stephanie; Slosar, Anze; Spergel, David N; Suzuki, Nao; Viel, Matteo; Weaver, Benjamin A

    2012-01-01

    We present the BOSS Lyman-alpha (Lya) Forest Sample from SDSS Data Release 9, comprising 54,468 quasar spectra with zqso > 2.15 suitable for Lya forest analysis. This data set probes the intergalactic medium with absorption redshifts 2.0 1216 Ang), extrapolated into the forest region and normalized by a linear function to fit the expected evolution of the Lya forest mean-flux. The estimated continuum errors are ~5% rms. We also discuss possible systematics arising from uncertain spectrophotometry and artifacts in the flux calibration; global corrections for the latter are provided. Our sample provides a convenient starting point for users to analyze clustering in BOSS Lya forest data, and it provides a fiducial data set that can be used to compare results from different analyses of baryon acoustic oscillations in the Lya forest. The full data set is available from the SDSS-III DR9 web site.

  3. Wandering in the Lyman-alpha forest: a study of dark matter-dark radiation interactions

    Science.gov (United States)

    Krall, Rebecca; Cyr-Racine, Francis-Yan; Dvorkin, Cora

    2017-09-01

    The amplitude of large-scale matter fluctuations inferred from the observed Sunyaev-Zeldovich (SZ) cluster mass function and from weak gravitational lensing studies, when taken at face value, is in tension with measurements of the cosmic microwave background (CMB) and baryon acoustic oscillation (BAO). In this work, we revisit whether this possible discrepancy can be attributed to new interactions in the dark matter sector. Focusing on a cosmological model where dark matter interacts with a dark radiation species until the epoch of matter-radiation equality, we find that measurements of the Lyman-alpha flux power spectrum from the Sloan Digital Sky Survey provide no support to the hypothesis that new dark matter interactions can resolve the possible tension between CMB and large-scale structure (LSS). Indeed, while the addition of dark matter-dark radiation interactions leads to an improvement of 2Δ&ln;Script L=12 with respect to the standard Λ cold dark matter (ΛCDM) model when only CMB, BAO, and LSS data are considered, the inclusion of Lyman-alpha data reduces the improvement of the fit to 2Δ&ln;Script L=6 relative to ΛCDM . We thus conclude that the statistical evidence for new dark matter interactions (largely driven by the Planck SZ dataset) is marginal at best, and likely caused by systematics in the data. We also perform a Fisher forecast analysis for the reach of a future dataset composed of a CMB-S4 experiment combined with the Large Synoptic Survey Telescope galaxy survey. We find that the constraint on the effective number of fluid-like dark radiation species, Δ Nfluid, will be improved by an order of magnitude compared to current bounds.

  4. Transiting the Sun II: The impact of stellar activity on Lyman-$\\alpha$ transits

    CERN Document Server

    Llama, J

    2015-01-01

    High-energy observations of the Sun provide an opportunity to test the limits of our ability to accurately measure properties of transiting exoplanets in the presence of stellar activity. Here we insert transits of a hot Jupiter into continuous disk integrated data of the Sun in Lyman-alpha (Ly$\\alpha$) from NASA's SDO/EVE instrument to assess the impact of stellar activity on the measured planet-to-star radius ratio $(\\textrm{R}_\\textrm{p}/\\textrm{R}_\\star)$. In 75% of our simulated light curves we measure the correct radius ratio; however, incorrect values can be measured if there is significant short term variability in the light curve. The maximum measured value of $(\\textrm{R}_\\textrm{p}/\\textrm{R}_\\star)$ is $50\\%$ larger than the input value, which is much smaller than the large Ly$\\alpha$ transit depths that have been reported in the literature, suggesting that for stars with activity levels comparable to the Sun, stellar activity alone cannot account for these deep transits. We ran simulations withou...

  5. H-alpha features with hot onsets III. Fibrils in Lyman-alpha and with ALMA

    CERN Document Server

    Rutten, Robert J

    2016-01-01

    In H-alpha most of the solar surface is covered by a dense canopy of long opaque fibrils, but predictions for quiet-Sun observations with ALMA have ignored this fact. Comparison with Ly-alpha suggests that the large opacity of H-alpha fibrils is caused by hot precursor events. Application of a recipe that assumes momentary Saha-Boltzmann extinction during their hot onset to millimeter wavelengths suggests that ALMA will observe the H-alpha fibril canopy, not acoustic shocks underneath, and will yield data more interesting than if this canopy were transparent.

  6. Elemental Abundances in Two High Column Density Damped Lyman Alpha Systems at z < 1.5

    CERN Document Server

    Rao, S M; Howk, J C; Wolfe, A M; Rao, Sandhya M.; Prochaska, Jason X.; Wolfe, Arthur M.

    2004-01-01

    We present Keck/HIRES abundance measurements and metal-line kinematic profiles of the damped Lyman alpha systems (DLAs) towards the quasars Q0933+733 (z_abs=1.479) and Q0948+433 (z_abs=1.233). These two DLAs have among the five highest HI column densities at any redshift: N(HI)=4.2E21 cm^{-2}. The metal-line data, presented here for the first time, reveal that these DLAs are noteworthy for several other reasons as well. 1) The Q0933+733 DLA exhibits simple kinematic structure with unusually narrow velocity widths as measured from its unsaturated metal lines (delta v=16 km/s). At 2.6% solar, it has the second lowest metallicity at z -1) and a significant alpha-enhancement. The strong metal lines of this DLA have made possible the detection of TiII1910, CoII2012, and MgI2026. 3) We find that the relative gas-phase abundances of both DLAs follow the general trend seen at high redshift, e.g., enhanced Zn/Fe and Si/Fe, and sub-solar Mn/Fe, indicating that there is little evolution in the nucleosynthetic patterns o...

  7. The Lyman Alpha Reference Sample: III. Properties of the Neutral ISM from GBT and VLA Observations

    CERN Document Server

    Pardy, Stephen A; Östlin, Göran; Hayes, Matthew; Rivera-Thorsen, Thøger; Sandberg, Andreas; Adamo, Angela; Freeland, Emily; Heren, E Christian; Guaita, Lucia; Kunth, Daniel; Laursen, Peter; Mas-Hesse, J M; Melinder, Jens; Orlitová, Ivana; Otí-Floranes, Héctor; Puschnig, Johannes; Schaerer, Daniel; Verhamme, Anne

    2014-01-01

    We present new H I imaging and spectroscopy of the 14 UV-selected star-forming galaxies in the Lyman Alpha Reference Sample (LARS), aimed for a detailed study of the processes governing the production, propagation, and escape of Ly$\\alpha$ photons. New H I spectroscopy, obtained with the 100m Green Bank Telescope (GBT), robustly detects the H I spectral line in 11 of the 14 observed LARS galaxies (although the profiles of two of the galaxies are likely confused by other sources within the GBT beam); the three highest redshift galaxies are not detected at our current sensitivity limits. The GBT profiles are used to derive fundamental H I line properties of the LARS galaxies. We also present new pilot H I spectral line imaging of 5 of the LARS galaxies obtained with the Karl G. Jansky Very Large Array (VLA). This imaging localizes the H I gas and provides a measurement of the total H I mass in each galaxy. In one system, LARS 03 (UGC 8335 or Arp 238), VLA observations reveal an enormous tidal structure that ext...

  8. Discovery of Ubiquitous Fast Propagating Intensity Disturbances by the Chromospheric Lyman Alpha Spectropolarimeter (CLASP)

    Science.gov (United States)

    Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Kano, R.; Bando, T.; Narukage, N.; Ishikawa, R.; Hara, H.; Giono, G.; Tsuneta, S.; Ishikawa, S.; Shimizu, T.; Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.; Auchere, F.; Bueno, J. Trujillo; Ramos, A. Asensio; Stepan, J.; Belluzzi, L.; Sainz, R. Manso; De Pontieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.; Goto, M.

    2016-01-01

    High cadence observations by the slit-jaw (SJ) optics system of the sounding rocket experiment known as the Chromospheric Lyman Alpha SpectroPolarimeter (CLASP) reveal ubiquitous intensity disturbances that recurrently propagate in one or both of the chromosphere or transition region at a speed much higher than the sound speed. The CLASP/SJ instrument provides a time series of 2D images taken with broadband filters centered on the Ly(alpha) line at a 0.6 s cadence. The fast propagating intensity disturbances are detected in the quiet Sun and in an active region, and at least 20 events are clearly detected in the field of view of 527'' x 527'' during the 5-minute observing time. The apparent speeds of the intensity disturbances range from 150 to 350 km/s, and they are comparable to the local Alfven speed in the transition region. The intensity disturbances tend to propagate along bright elongated structures away from areas with strong photospheric magnetic fields. This suggests that the observed propagating intensity disturbances are related to the magnetic canopy structures. The maximum distance traveled by the intensity disturbances is of about 10'', and the widths are a few arcseconds, which is almost determined by the pixel size of 1.''03. The timescale of each intensity pulse is shorter than 30 s. One possible explanation of the fast propagating intensity disturbances observed by CLASP is magneto-hydrodynamic fast mode waves.

  9. Chemical abundances of damped Lyman alpha systems in the XQ-100 survey

    CERN Document Server

    Berg, T A M; Sanchez-Ramirez, R; Prochaska, J X; Lopez, S; D'Odorico, V; Becker, G; Christensen, L; Cupani, G; Denney, K; Worsek, G

    2016-01-01

    The XQ-100 survey has provided high signal-noise spectra of 100 redshift 3-4.5 quasars with the X-Shooter spectrograph. The metal abundances for 13 elements in the 41 damped Lyman alpha systems (DLAs) identified in the XQ-100 sample are presented, and an investigation into abundances of a variety of DLA classes is conducted. The XQ-100 DLA sample contains five DLAs within 5000 km/s of their host quasar (proximate DLAs; PDLAs) as well as three sightlines which contain two DLAs within 10,000 km/s of each other along the same line-of-sight (multiple DLAs; MDLAs). Combined with previous observations in the literature, we demonstrate that PDLAs with logN(HI)21.0. These abundance discrepancies are independent of their line-of-sight velocity separation from the host quasar, and the velocity width of the metal lines (v90). Contrary to previous studies, MDLAs show no difference in [alpha/Fe] relative to single DLAs matched in metallicity and redshift. In addition, we present follow-up UVES data of J0034+1639, a sightl...

  10. Optimizing BAO measurements with non-linear transformations of Lyman-alpha forest

    CERN Document Server

    Wang, Xinkang; Seljak, Uros

    2014-01-01

    We explore the effect of applying a non-linear transformation to the Lyman-$\\alpha$ forest transmitted flux $F=e^{-\\tau}$ and the ability of analytic models to predict the resulting clustering amplitude. Both the large-scale bias of the transformed field (signal) and the amplitude of small scale fluctuations (noise) can be arbitrarily modified, but we were unable to find a transformation that increases significantly the signal-to-noise ratio on large scales using Taylor expansion up to third order. We achieve a 33% improvement in signal to noise for Gaussianized field in transverse direction. On the other hand, we explore analytic model for the large-scale biasing of the Ly$\\alpha$ forest, and present an extension of this model to describe the biasing of the transformed fields. Using hydrodynamic simulations we show that the model works best to describe the biasing with respect to velocity gradients, but is less successful in predicting the biasing with respect to large-scale density fluctuations, especially ...

  11. The Evolution of Damped Lyman-alpha Absorbers: Metallicities and Star Formation Rates

    CERN Document Server

    Kulkarni, V P; Lauroesch, J T; Fall, S M; Khare, P; Woodgate, B E; Palunas, P; Meiring, J; Thatte, D G; Welty, D E; Truran, J W; Kulkarni, Varsha P.; York, Donald G.; Lauroesch, James T.; Khare, Pushpa; Woodgate, Bruce E.; Palunas, Povilas; Meiring, Joseph; Thatte, Deepashri G.; Welty, Daniel E.; Truran, James W.

    2005-01-01

    The damped Lyman-alpha (DLA) and sub-DLA quasar absorption lines provide powerful probes of the evolution of metals, gas, and stars in galaxies. One major obstacle in trying to understand the evolution of DLAs and sub-DLAs has been the small number of metallicity measurements at z < 1.5, an epoch spanning \\~70 % of the cosmic history. In recent surveys with the Hubble Space Telescope and Multiple Mirror Telescope, we have doubled the DLA Zn sample at z < 1.5. Combining our results with those at higher redshifts from the literature, we find that the global mean metallicity of DLAs does not rise to the solar value at low redshifts. These surprising results appear to contradict the near-solar mean metallicity observed for nearby (z ~ 0) galaxies and the predictions of cosmic chemical evolution models based on the global star formation history. Finally, we discuss direct constraints on the star formation rates (SFRs) in the absorber galaxies from our deep Fabry-Perot Ly-alpha imaging study and other emissio...

  12. Lyman-alpha forest-CMB cross-correlation and the search for the ionized baryons at high redshift

    CERN Document Server

    Croft, R A C; Hernquist, L; Croft, Rupert A.C.; Hernquist, Lars

    2005-01-01

    The intergalactic neutral hydrogen which is responsible for the Lyman alpha forest of quasar absorption is a tracer of much larger amounts of ionised hydrogen. The ionised component has yet to be detected directly, but is expected to scatter CMB photons via the Sunyaev-Zel'dovich (SZ) effect. We use hydrodynamic simulations of a LambdaCDM universe to create mock quasar spectra and CMB sky maps. We find that the high-z Lya forest gas causes temperature fluctuations of the order of 1 muK rms in the CMB on arcmin scales. The kinetic and thermal SZ effects have a similar magnitude at z=3, with the thermal effect becoming relatively weaker as expected at higher z. The CMB signal associated with lines of sight having HI column densities > 10^18 cm^-2 is only marginally stronger than that for lower column densities. The strong dependence of rms temperature fluctuation on mean Lya absorbed flux, however, suggests that the CMB signal effectively arises in lower density material. We investigate the use of the cross-cor...

  13. Observed Faraday Effects in Damped Lyman-Alpha Absorbers and Lyman Limit Systems: The Magnetised Environment of Galactic Building Blocks at Redshift=2

    CERN Document Server

    Farnes, J S; Gaensler, B M; Haverkorn, M; O'Sullivan, S P; Curran, S J

    2016-01-01

    Protogalactic environments are typically identified using quasar absorption lines, and these galactic building blocks can manifest as Damped Lyman-Alpha Absorbers (DLAs) and Lyman Limit Systems (LLSs). We use radio observations of Faraday effects to test whether DLAs and LLSs host a magnetised medium, by combining DLA and LLS detections throughout the literature with 1.4 GHz polarization data from the NRAO VLA Sky Survey (NVSS). We obtain a control, a DLA, and a LLS sample consisting of 114, 19, and 27 lines-of-sight respectively - all of which are polarized at $\\ge8\\sigma$ to ensure Rician bias is negligible. Using a Bayesian framework, we are unable to detect either coherent or random magnetic fields in DLAs: the regular coherent magnetic fields within the DLAs must be $\\le2.8$ $\\mu$G, and the lack of depolarization is consistent with the weakly magnetised gas in DLAs being non-turbulent and quiescent. However, we find mild suggestive evidence that LLSs have coherent magnetic fields: after controlling for t...

  14. Diagnosing the reionization of the universe - The absorption spectrum of the intergalactic medium and Lyman alpha clouds

    Science.gov (United States)

    Giroux, Mark L.; Shapiro, Paul R.

    1991-01-01

    The thermal and ionization evolution of a uniform intergalactic medium composed of H and He and undergoing reionization is studied. The diagnosis of the metagalactic ionizing radiation background at z of about three using metal line ratios for Lyman limit quasar absorption line systems is addressed. The use of the He II Gunn-Peterson effect to diagnose the reionization source and/or nature of the Hy-alpha forest clouds is considered.

  15. Performance Characterization of UV Science Cameras Developed for the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

    Science.gov (United States)

    Champey, Patrick; Kobayashi, Ken; Winebarger, Amy; Cirtin, Jonathan; Hyde, David; Robertson, Bryan; Beabout, Brent; Beabout, Dyana; Stewart, Mike

    2014-01-01

    The NASA Marshall Space Flight Center (MSFC) has developed a science camera suitable for sub-orbital missions for observations in the UV, EUV and soft X-ray. Six cameras will be built and tested for flight with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), a joint National Astronomical Observatory of Japan (NAOJ) and MSFC sounding rocket mission. The goal of the CLASP mission is to observe the scattering polarization in Lyman-alpha and to detect the Hanle effect in the line core. Due to the nature of Lyman-alpha polarization in the chromosphere, strict measurement sensitivity requirements are imposed on the CLASP polarimeter and spectrograph systems; science requirements for polarization measurements of Q/I and U/I are 0.1% in the line core. CLASP is a dual-beam spectro-polarimeter, which uses a continuously rotating waveplate as a polarization modulator, while the waveplate motor driver outputs trigger pulses to synchronize the exposures. The CCDs are operated in frame-transfer mode; the trigger pulse initiates the frame transfer, effectively ending the ongoing exposure and starting the next. The strict requirement of 0.1% polarization accuracy is met by using frame-transfer cameras to maximize the duty cycle in order to minimize photon noise. Coating the e2v CCD57-10 512x512 detectors with Lumogen-E coating allows for a relatively high (30%) quantum efficiency at the Lyman-$\\alpha$ line. The CLASP cameras were designed to operate with =10 e- /pixel/second dark current, = 25 e- read noise, a gain of 2.0 and =0.1% residual non-linearity. We present the results of the performance characterization study performed on the CLASP prototype camera; dark current, read noise, camera gain and residual non-linearity.

  16. The MUSCLES Treasury Survey II: Intrinsic Lyman Alpha and Extreme Ultraviolet Spectra of K and M Dwarfs with Exoplanets

    CERN Document Server

    Youngblood, Allison; Loyd, R O Parke; Linsky, Jeffrey L; Redfield, Seth; Schneider, P Christian; Wood, Brian E; Brown, Alexander; Froning, Cynthia; Miguel, Yamila; Rugheimer, Sarah; Walkowicz, Lucianne

    2016-01-01

    The ultraviolet (UV) spectral energy distributions of low-mass (K- and M-type) stars play a critical role in the heating and chemistry of exoplanet atmospheres, but are not observationally well-constrained. Direct observations of the intrinsic flux of the Lyman alpha line (the dominant source of UV photons from low-mass stars) are challenging, as interstellar HI absorbs the entire line core for even the closest stars. To address the existing gap in empirical constraints on the UV flux of K and M dwarfs, the MUSCLES HST Treasury Survey has obtained UV observations of 11 nearby M and K dwarfs hosting exoplanets. This paper presents the Lyman alpha and extreme-UV spectral reconstructions for the MUSCLES targets. Most targets are optically inactive, but all exhibit significant UV activity. We use a Markov Chain Monte Carlo technique to correct the observed Lyman alpha profiles for interstellar absorption, and we employ empirical relations to compute the extreme-UV spectral energy distribution from the intrinsic L...

  17. On the inversion of the scattering polarization and the Hanle effect signals in the hydrogen Lyman-$\\alpha$ line

    CERN Document Server

    Ishikawa, R; Belluzzi, L; Sainz, R Manso; Stepan, J; Bueno, J Trujillo; Goto, M; Tsuneta, S

    2014-01-01

    Magnetic field measurements in the upper chromosphere and above, where the gas-to-magnetic pressure ratio $\\beta$ is lower than unity, are essential for understanding the thermal structure and dynamical activity of the solar atmosphere. Recent developments in the theory and numerical modeling of polarization in spectral lines have suggested that information on the magnetic field of the chromosphere-corona transition region could be obtained by measuring the linear polarization of the solar disk radiation at the core of the hydrogen Lyman-$\\alpha$ line at 121.6~nm, which is produced by scattering processes and the Hanle effect. The Chromospheric Lyman-$\\alpha$ Spectropolarimeter (CLASP) sounding rocket experiment aims to measure the intensity (Stokes $I$) and the linear polarization profiles ($Q/I$ and $U/I$) of the hydrogen Lyman-$\\alpha$ line. In this paper we clarify the information that the Hanle effect can provide by applying a Stokes inversion technique based on a database search. The database contains a...

  18. COMPARISON OF PIONEER 10, VOYAGER 1, AND VOYAGER 2 ULTRAVIOLET OBSERVATIONS WITH ANTI-SOLAR LYMAN-ALPHA BACKSCATTER SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Fayock, B.; Zank, G. P.; Heerikhuisen, J., E-mail: brian.fayock@gmail.com, E-mail: garyp.zank@gmail.com, E-mail: jacob.heerikhuisen@uah.edu [Department of Physics and Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2013-09-20

    Observations made by ultraviolet (UV) detectors on board Pioneer 10, Voyager 1, and Voyager 2 can be used to analyze the distribution of neutral hydrogen throughout the heliosphere, including the interaction regions of the solar wind and local interstellar medium. Previous studies of the long-term trend of decreasing intensity with increasing heliocentric distance established the need for more sophisticated heliospheric models. Here we use state-of-the-art three-dimensional (3D) magnetohydrodynamic (MHD) neutral models to simulate Lyman-alpha backscatter as would be seen by the three spacecrafts, exploiting a new 3D Monte Carlo radiative transfer code under solar minimum conditions. Both observations and simulations of the UV backscatter intensity are normalized for each spacecraft flight path at {approx}15 AU, and we focus on the slope of decreasing intensity over an increasing heliocentric distance. Comparisons of simulations with Voyager 1 Lyman-alpha data results in a very close match, while the Pioneer 10 comparison is similar due to normalization, but not considered to be in agreement. The deviations may be influenced by a low resolution of photoionization in the 3D MHD-neutral model, a lack of solar cycle activity in our simulations, and possibly issues with instrumental sensitivity. Comparing the slope of Voyager 2 and the simulated intensities yields an almost identical match. Our results predict a large increase in the Lyman-alpha intensity as the hydrogen wall is approached, which would signal an imminent crossing of the heliopause.

  19. Ionized Gas in Damped Lyman Alpha Protogalaxies II. Comparison Between Models and the Kinematic Data

    CERN Document Server

    Wolfe, A M; Wolfe, Arthur M.

    2000-01-01

    We test semi-analytic models for galaxy formation with accurate kinematic data of damped Lyman alpha protogalaxies (DLAs) presented in the companion paper I. The models envisage centrifugally supported exponential disks at the centers of dark matter halos which are filled with ionized gas undergoing radial infall to the disks. The halo masses are drawn from cross-section weighted mass distributions predicted by CDM cosmogonies, or by the null hypothesis (TF model) that the dark matter mass distribution has not evolved since z ~ 3. In our models, C IV absorption lines detected in DLAs arise in infalling ionized clouds while the low-ion absorption lines arise from neutral gas in the disks. Using Monte Carlo methods we find: (a) The CDM models are incompatible with the low-ion statistics at more than 99% confidence whereas some TF models cannot be excluded at more than 88% confidence. (b) Both CDM and TF models agree with the observed distribution of C IV velocity widths. (c) The CDM models generate differences ...

  20. C, N, O Abundances in the Most Metal-Poor Damped Lyman alpha Systems

    CERN Document Server

    Pettini, Max; Steidel, Charles C; Chaffee, Fred H

    2007-01-01

    This study focuses on some of the most metal-poor damped Lyman alpha absorbers known in the spectra of high redshift QSOs, using new and archival observations obtained with UV-sensitive echelle spectrographs on the Keck and VLT telescopes. The weakness and simple velocity structure of the absorption lines in these systems allows us to measure the abundances of several elements, and in particular those of C, N, and O, a group that is difficult to study in DLAs of more typical metallicities. We find that when the oxygen abundance is less than about 1/100 of solar, the C/O ratio in high redshift DLAs and sub-DLAs matches that of halo stars of similar metallicity and shows higher values than expected from galactic chemical evolution models based on conventional stellar yields. Furthermore, there are indications that at these low metallicities the N/O ratio may also be above simple expectations and may exhibit a minimum value, as proposed by Centurion and her collaborators in 2003. Both results can be interpreted ...

  1. The effect of dust geometry on the Lyman-alpha output of galaxies

    CERN Document Server

    Scarlata, C; Teplitz, H I; Panagia, N; Hayes, M; Siana, B; Rau, A; Francis, P; Caon, A; Pizzella, A; Bridge, C

    2009-01-01

    We present the optical spectroscopic follow-up of 31 z=0.3 Lyman-alpha (Lya) emitters, previously identified by Deharveng et al. (2008). We find that 17% of the Lya emitters have line ratios that require the hard ionizing continuum produced by an AGN. The uniform dust screen geometry traditionally used in studies similar to ours is not able to simultaneously reproduce the observed high Lya/Halpha and Halpha/Hbeta line ratios. We consider different possibilities for the geometry of the dust around the emitting sources. We find that also a uniform mixture of sources and dust does not reproduce the observed line ratios. Instead, these are well reproduced by a clumpy dust screen. This more realistic treatment of the geometry results in extinction corrected (Lya/Halpha)_C values consistent with Case B recombination theory, whereas a uniform dust screen model would imply values (Lya/Halpha)_C higher than 8.7. Our analysis shows that there is no need to invoke "ad-hoc" multi phase media in which the Lya photons only...

  2. HeII emission in Lyman-alpha nebulae: AGN or cooling radiation?

    CERN Document Server

    Scarlata, C; Teplitz, H I; Bridge, C; Francis, P; Palunas, P; Siana, B; Williger, G M; Woodgate, B

    2009-01-01

    We present a study of an extended Lyman-alpha (Lya) nebula located in a known overdensity at z~2.38. The data include multiwavelength photometry covering the rest-frame spectral range from 0.1 to 250um, and deep optical spectra of the sources associated with the extended emission. Two galaxies are associated with the Lya nebula. One of them is a dust enshrouded AGN, while the other is a powerful starburst, forming stars at >~600 Msol/yr. We detect the HeII emission line at 1640A in the spectrum of the obscured AGN, but detect no emission from other highly ionized metals (CIV or NV) as is expected from an AGN. One scenario that simultaneously reproduces the width of the detected emission lines, the lack of CIV emission, and the geometry of the emitting gas, is that the HeII and the Lya emission are the result of cooling gas that is being accreted on the dark matter halo of the two galaxies, Ly1 and Ly2. Given the complexity of the environment associated with our Lya nebula it is possible that various mechanism...

  3. The Column Density Distribution of the Low-Redshift Lyman-Alpha Forest in Illustris

    CERN Document Server

    Gurvich, Alex; Bird, Simeon

    2016-01-01

    We investigate the low-redshift Lyman-alpha forest column density distribution in the Illustris simulation. We show that Illustris reproduces observations extremely well in the column density range 10^12.5-10^14.5 cm^-2, relevant for the "photon underproduction crisis." We attribute this to the inclusion of AGN feedback, which changes the gas distribution so as to mimic the effect of extra photons, as well as the use of the Faucher-Giguere (2009) ultra-violet background, which is more ionizing at z=0.1 than the Haardt & Madau (2012) background previously considered. We show that the difference between simulations run with smoothed particle hydrodynamics and simulations using a moving mesh is small in this column density range. We further consider the effect of supernova feedback, Voigt profile fitting and finite resolution, all of which we show to be small. Finally, we identify a discrepancy between our simulations and observations at column densities 10^14-10^16 cm^-2, where Illustris produces too few ab...

  4. From Exoplanets to Quasars: Detection of Potential Damped Lyman Alpha Absorbing Galaxies Using Angular Differential Imaging

    CERN Document Server

    Johnson-Groh, Mara; Ellison, Sara L

    2016-01-01

    The advantages of angular differential imaging (ADI) has been previously untested in imaging the host galaxies of damped Lyman alpha (DLA) systems. In this pilot study, we present the first application of ADI to directly imaging the host galaxy of the DLA seen towards the quasar J1431+3952. K-band imaging of the field surrounding J1431+3952 was obtained on the Gemini North telescope with the adaptive optics system and a laser guide star. We computed a sensitivity curve that demonstrates the sensitivity of our observations as a function of K-band magnitude, impact parameter and DLA angular size. For an impact parameter of 0.5" (3.4 kpc at the redshift of the absorber) our mass sensitivity is log (M_star/M_sun) ~ 9.2 and drops to ~ 9.0 at separations beyond ~ 6 kpc for the smallest size model galaxy. Three candidate galaxies are identified within 5". Stellar masses were computed from the K-band photometry yielding values of log (M_star/M_sun) ~ 9.9, 9.7 and 11.1 respectively. The likely identification of the ab...

  5. The Mean Metal-line Absorption Spectrum of Damped Lyman Alpha Systems in BOSS

    CERN Document Server

    Mas-Ribas, Lluís; Pérez-Ràfols, Ignasi; Arinyo-i-Prats, Andreu; Noterdaeme, Pasquier; Petitjean, Patrick; Schneider, Donald P; York, Donald G; Ge, Jian

    2016-01-01

    We study the average absorption spectrum of the Damped Lyman Alpha system (DLA) population at $z ~ 2.5$ by stacking normalized, rest-frame shifted spectra of $\\sim 27\\,000$ DLAs from the Data Release 12 of the BOSS survey of SDSS-III. We list measurements of the mean equivalent width of 50 individual metal absorption lines in 5 intervals of DLA hydrogen column density $N_{\\rm HI}$, and overall mean equivalent widths for an additional 13 absorption features from groups of strongly blended lines. We show that the mean equivalent width of low-ionization lines increases with $N_{\\rm HI}$ as expected, but this increase is much weaker or non-existent for high-ionization lines. We develop a theoretical model to infer mean column densities from the equivalent widths of partially saturated lines, based on the presence of multiple absorption components observed in high-resolution spectra. We use this model to infer mean column densities in DLAs of 14 low-ionization species, as well as for AlIII, SIII, SiIII, CIV, SiIV,...

  6. The Chemical Evolution of Very Metal-Poor Damped Lyman-$\\alpha$ Systems

    CERN Document Server

    Webster, David; Sutherland, Ralph S

    2015-01-01

    In earlier work we showed that a dark matter halo with a virial mass of $10^7$ M$_\\odot$ can survive feedback from its own massive stars and form stars for $\\gtrsim100$ Myr. We also found that our modelled systems were consistent with observations of ultrafaint dwarfs (UFDs), the least massive known galaxies. Very metal-poor damped Lyman-$\\alpha$ systems (DLAs) recently identified at $z\\sim2$ may represent the gas that formed at least some of the observed stars in UFDs. We compare projected sightlines from our simulations to the observed metal-poor DLAs and find that our models can reach the densities of the observed sightlines; however the metallicities are inconsistent with the single supernova simulations, suggesting enrichment by multiple supernovae. We model two scenarios for the history of these systems. The first explains the gas abundances in DLAs by a single burst of star formation. This model can produce the observed DLA abundances, but does not provide an explanation as to why the DLAs show suppres...

  7. Damped Lyman-alpha absorbers as a probe of stellar feedback

    CERN Document Server

    Bird, Simeon; Haehnelt, Martin; Sijacki, Debora; Genel, Shy; Torrey, Paul; Springel, Volker; Hernquist, Lars

    2014-01-01

    We examine the abundance, clustering and metallicity of Damped Lyman-$\\alpha$ Absorbers (DLAs) in hydrodynamic cosmological simulations using the moving mesh code AREPO. We incorporate models of supernova and AGN feedback, and molecular hydrogen formation. We compare our simulations to the column density distribution function at $z=3$, the total DLA abundance at $z=2-4$, the measured DLA bias at $z=2$ and DLA metallicities at $z=2-4$. Our preferred models produce populations of DLAs in good agreement with most of these observations, except the DLA abundance at $z < 3$, which we show requires stronger feedback in $10^{11-12} h^{-1} M_\\odot$ mass halos. While the DLA population probes a range of halo masses, we find the cross-section is dominated by halos of mass $10^{10.5} h^{-1} M_\\odot$ at $z=3$ and $10^{11} h^{-1} M_\\odot$ at $z=2$. Simulations without feedback are in strong tension with all these observables, indicating a need for strong stellar feedback at $z=2-4$ independently of the star formation th...

  8. The Curious Case of Lyman Alpha Emitters: Growing Younger from z ~ 3 to z ~ 2?

    CERN Document Server

    Acquaviva, Viviana; Gawiser, Eric; Guaita, Lucia

    2011-01-01

    Lyman Alpha Emitting (LAE) galaxies are thought to be progenitors of present-day L* galaxies. Clustering analyses have suggested that LAEs at z ~ 3 might evolve into LAEs at z ~ 2, but it is unclear whether the physical nature of these galaxies is compatible with this hypothesis. Several groups have investigated the properties of LAEs using spectral energy distribution (SED) fitting, but direct comparison of their results is complicated by inconsistencies in the treatment of the data and in the assumptions made in modeling the stellar populations, which are degenerate with the effects of galaxy evolution. By using the same data analysis pipeline and SED fitting software on two stacked samples of LAEs at z = 3.1 and z = 2.1, and by eliminating several systematic uncertainties that might cause a discrepancy, we determine that the physical properties of these two samples of galaxies are dramatically different. LAEs at z = 3.1 are found to be old (age ~ 1 Gyr) and metal-poor (Z Z_Sun). The difference in the obse...

  9. HST/ACS Lyman alpha imaging of the nearby starburst ESO338-IG04

    CERN Document Server

    Hayes, M; Mas-Hesse, J M; Kunth, D; Leitherer, C; Petrosian, A

    2005-01-01

    ESO338-IG04 is a well known, local, luminous Blue Compact Galaxy. It has a complex morphology and contains a central young starburst with compact young star clusters. The galaxy was imaged using HST/ACS in the Lyman alpha line and continuum. Using the Starburst99 synthetic spectra and other imaging data from HST/WFPC2 we developed a technique that allows us to make the first photometrically valid continuum subtraction for the LYa line. Our results are in qualitative agreement with the models of LYa escape being regulated by kinematical properties of the interstellar medium. The line-only image shows LYa in both emission and absorption. Notably, emission is seen from central bright young clusters and is in spatial agreement with the features present in a longslit spectrum taken with HST/STIS. Diffuse LYa emission regions are seen surrounding the central starburst where photons escape after one or more resonant scatterings in HI. These regions dominate the total LYa output. Photometry reveals a total LYa flux o...

  10. The Luminosity Function of Lyman Alpha Emitting Galaxies and Cosmic Reionisation of Hydrogen

    CERN Document Server

    Dijkstra, M; Haiman, Z; Dijkstra, Mark; Wyithe, Stuart; Haiman, Zoltan

    2006-01-01

    Recent observations imply that the observed number counts of Lyman Alpha (Lya) emitters evolved significantly between z=5.7 and z=6.5. It has been suggested that this evolution was due to a rapid evolution in the ionisation state, and hence transmission of the IGM which caused Lya flux from z=6.5 galaxies to be more strongly suppressed. In this paper we show that the observed evolution can be attributed entirely to the evolution in the mass function of dark matter halos housing the Lya emitters. We place constraints on the evolution of transmission in the IGM between z=6.5 and z=5.7, finding a ratio of ~1.2, which may be accounted for by the evolution of the mean IGM density through cosmic expansion. Using a model for IGM transmission, we demonstrate that Lya emitting galaxies at z=6.5 must be embedded in HII bubbles greater than 35x_HI comoving Mpc in size, where x_HI is the neutral fraction of hydrogen outside the ionised bubbles. The model of Furlanetto et al (2006) may be used to translate this into a low...

  11. Constraining quasar host halo masses with the strength of nearby Lyman-alpha forest absorption

    CERN Document Server

    Kim, Y R; Kim, Young-Rae; Croft, Rupert

    2006-01-01

    Using cosmological hydrodynamic simulations we measure the mean transmitted flux in the Lyman alpha forest for quasar sightlines that pass near a foreground quasar. We find that the trend of absorption with pixel-quasar separation distance can be fitted using a simple power law form including the usual correlation function parameters r_{0} and \\gamma so that ( = \\sum exp(-tau_eff*(1+(r/r_{0})^(-\\gamma)))). From the simulations we find the relation between r_{0} and quasar mass and formulate this as a way to estimate quasar host dark matter halo masses, quantifying uncertainties due to cosmological and IGM parameters, and redshift errors. With this method, we examine data for ~3000 quasars from the Sloan Digital Sky Survey (SDSS) Data Release 3, assuming that the effect of ionizing radiation from quasars (the so-called transverse proximity effect) is unimportant (no evidence for it is seen in the data.) We find that the best fit host halo mass for SDSS quasars with mean redshift z=3 and absolute G band magnitu...

  12. The evolution of neutral gas in damped Lyman $\\alpha$ systems from the XQ-100 survey

    CERN Document Server

    Sánchez-Ramírez, R; Prochaska, J X; Berg, T A M; López, S; D'Odorico, V; Becker, G D; Christensen, L; Cupani, G; Denney, K D; Pâris, I; Worseck, G; Gorosabel, J

    2015-01-01

    We present a sample of 38 intervening Damped Lyman $\\alpha$ (DLA) systems identified towards 100 $z>3.5$ quasars, observed during the XQ-100 survey. The XQ-100 DLA sample is combined with major DLA surveys in the literature. The final combined sample consists of 742 DLAs over a redshift range approximately $1.6 < z_{\\rm abs} < 5.0$. We develop a novel technique for computing $\\Omega_{\\rm HI}^{\\rm DLA}$ as a continuous function of redshift, and we thoroughly assess and quantify the sources of error therein, including fitting errors and incomplete sampling of the high column density end of the column density distribution function. There is a statistically significant redshift evolution in $\\Omega_{\\rm HI}^{\\rm DLA}$ ($\\geq 3 \\sigma$) from $z \\sim 2$ to $z \\sim$ 5. In order to make a complete assessment of the redshift evolution of $\\Omega_{\\rm HI}$, we combine our high redshift DLA sample with absorption surveys at intermediate redshift and 21cm emission line surveys of the local universe. Although $\\Omeg...

  13. Constraints on the gas masses of low-z damped Lyman-$\\alpha$ systems

    CERN Document Server

    Mazumdar, Parichay; Prochaska, J Xavier

    2014-01-01

    We report a deep search for redshifted HI 21 cm emission from three damped and sub-damped Lyman-$\\alpha$ absorbers (DLAs) at $z \\approx 0.1$ with the Green Bank Telescope (GBT). No evidence for a redshifted HI 21 cm emission signal was obtained in the GBT spectra of two absorbers, with the data on the third rendered unusable by terrestrial interference. The non-detections of HI 21 cm emission yield strong constraints on the HI masses of the associated galaxies, M$_{\\rm HI} < 2.3 \\times 10^9 \\times (\\Delta V/100)^{1/2}$ M$_\\odot$ for the sub-DLA at $z = 0.0830$ towards J1553+3548, and M$_{\\rm HI} < 2.7 \\times 10^9 \\times (\\Delta V/100)^{1/2}$ M$_\\odot$ for the DLA at $z = 0.0963$ towards J1619+3342, where $\\Delta V$ is the HI 21 cm line width, in km s$^{-1}$. This continues the trend of low HI masses found in all low-$z$ DLAs and sub-DLAs that have been searched for redshifted HI 21 cm emission. Low-redshift absorbers with relatively low HI column densities, $\\lesssim few \\times 10^{20}$ cm$^{-2}$, thus ...

  14. The First Observations of Low Redshift Damped Lyman-alpha Systems with the Cosmic Origins Spectrograph

    CERN Document Server

    Meiring, Joseph D; Prochaska, Jason X; Tumlinson, Jason; Werk, Jessica; Jenkins, Edward B; Thom, Chris; O'Meara, John M; Sembach, Kenneth R

    2011-01-01

    We report on the first Cosmic Origins Spectrograph (COS) observations of damped and sub-damped Lyman-alpha (DLA) systems discovered in a new survey of the gaseous halos of low-redshift galaxies. From observations of 37 sightlines, we have discovered three DLAs and four sub-DLAs. We measure the neutral gas density Omega(HI), and redshift density dN/dz, of DLA and sub-DLA systems at z<0.35. We find dN/dz=0.25 and Omega(HI)=1.4x10^-3 for DLAs, and dN/dz=0.08 with Omega(HI)=4.2x10^-5 for sub-DLAs over a redshift path delta z=11.9. To demonstrate the scientific potential of such systems, we present a detailed analysis of the DLA at z=0.1140 in the spectrum of SDSS J1009+0713. Profile fits to the absorption lines determine log N(H I)=20.68pm0.10 with a metallicity determined from the undepleted element Sulfur of [S/H]=-0.62pm0.18. The abundance pattern of this DLA is similar to that of higher z DLAs, showing mild depletion of the refractory elements Fe and Ti with [S/Fe]=+0.24pm0.22 and [S/Ti]=+0.28pm0.15. Nitro...

  15. The Low Redshift Lyman $\\alpha$ Forest in Cold Dark Matter Cosmologies

    CERN Document Server

    Davé, R; Katz, N; Weinberg, D H; Davé, Romeel; Hernquist, Lars; Katz, Neal; Weinberg, David

    1999-01-01

    We study the physical origin of the low-redshift Lyman alpha forest in hydrodynamic simulations of four CDM cosmologies. Our main conclusions are insensitive to the cosmological model but depend on our assumption that the UV background declines at low redshift. We find that the expansion of the universe drives rapid evolution of dN/dz (the number of absorbers per unit z) at z > 1.7, but that at lower redshift the fading of the UV background counters the influence of expansion, leading to slow evolution. At every redshift, weaker lines come primarily from moderate fluctuations of the diffuse, unshocked IGM, and stronger lines originate in shocked or radiatively cooled gas of higher overdensity. However, the neutral hydrogen column density associated with structures of fixed overdensity drops as the universe expands, so an absorber at z = 0 is dynamically analogous to an absorber with neutral hydrogen column density 10 to 50 times higher at z = 2-3. We find no clear distinction between lines arising in "galaxy ...

  16. Quasar-Lyman $\\alpha$ Forest Cross-Correlation from BOSS DR11 : Baryon Acoustic Oscillations

    CERN Document Server

    Font-Ribera, Andreu; Busca, Nicolas; Miralda-Escudé, Jordi; Ross, Nicholas P; Slosar, Anže; Aubourg, Éric; Bailey, Stephen; Bhardwaj, Vaishali; Bautista, Julian; Beutler, Florian; Bizyaev, Dmitry; Blomqvist, Michael; Brewington, Howard; Brinkmann, Jon; Brownstein, Joel R; Carithers, Bill; Dawson, Kyle S; Delubac, Timothée; Ebelke, Garrett; Eisenstein, Daniel J; Ge, Jian; Kinemuchi, Karen; Lee, Khee-Gan; Malanushenko, Viktor; Malanushenko, Elena; Marchante, Moses; Margala, Daniel; Muna, Demitri; Myers, Adam D; Noterdaeme, Pasquier; Oravetz, Daniel; Palanque-Delabrouille, Nathalie; Pâris, Isabelle; Petitjean, Patrick; Pieri, Matthew M; Rossi, Graziano; Schneider, Donald P; Simmons, Audrey; Viel, Matteo; Yeche, Christophe; York, Donald G

    2013-01-01

    We measure the large-scale cross-correlation of quasars with the Lyman alpha forest absorption, using over 164,000 quasars from Data Release 11 of the SDSS-III Baryon Oscillation Spectroscopic Survey. We extend the previous study of roughly 60,000 quasars from Data Release 9 to larger separations, allowing a measurement of the Baryonic Acoustic Oscillation (BAO) scale along the line of sight $c/(H(z=2.36) ~ r_s) = 9.0 \\pm 0.3$ and across the line of sight $D_A(z=2.36)~ / ~ r_s = 10.8 \\pm 0.4$, consistent with CMB and other BAO data. Using the best fit value of the sound horizon from Planck data ($r_s=147.49 Mpc$), we can translate these results to a measurement of the Hubble parameter of $H(z=2.36) = 226 \\pm 8 km/s$ and of the angular diameter distance of $D_A(z=2.36) = 1590 \\pm 60 Mpc$. The measured cross-correlation function and an update of the code to fit the BAO scale (baofit) are made publicly available.

  17. An 80-kpc Lyman-alpha halo around a high redshift type-2 QSO

    CERN Document Server

    Smith, Daniel J B; Simpson, Chris; Martinez-Sansigre, Alejo

    2008-01-01

    We announce the discovery of an extended emission line region associated with a high redshift type-2 QSO. The halo, which was discovered in our new wide-field narrow-band survey, resides at z = 2.85 in the Spitzer First Look Survey region and is extended over ~80 kpc. Deep VLBI observations imply that approximately 50 per cent of the radio emission is extended on scales > 200pc. The inferred AGN luminosity is sufficient to ionize the extended halo, and the optical emission is consistent with being triggered coevally with the radio source. The Lyman-alpha halo is as luminous as those found around high redshift radio galaxies, however the active nucleus is several orders of magnitude less luminous at radio wavelengths than those FRIIs more commonly associated with extended emission line regions. AMS05 appears to be a high-redshift analogue to the radio-quiet quasar E1821+643 which is core dominated but which also exhibits extended FRI-like structure and contains an optically powerful AGN. We also find evidence ...

  18. On Detecting the X-ray Silhouette of a Damped Lyman alpha System

    CERN Document Server

    Dijkstra, M; Schärf, C; Dijkstra, Mark; Haiman, Zoltan; Scharf, Caleb

    2004-01-01

    We explore the possibility of resolving an image of a damped Lyman alpha (DLA) system in absorption against an extended, diffuse background X-ray source. Typical columns of neutral hydrogen in DLAs are high enough to block out up to ~30% of the soft X-ray flux at an observed photon energy of 0.5 keV, and we find that ~ 1% of the area of extended X-ray sources at z > 1 have their 0.5 keV flux reduced by at least 20%. We discuss the observability of such absorption and find that 300 photons per angular resolution element are required in the 0.3-8 keV band for its detection, and in order to distinguish it from intrinsic surface brightness fluctuations. For the surface brightness of the currently known high-redshift extended X-ray sources, this requires an integration time of a few Msec on Chandra. The detection will be within the reach of a routine observation with a next generation X-ray telescope such as XEUS or Generation X.

  19. The Luminosity Function of Lyman alpha Emitters at Redshift z=7.7

    CERN Document Server

    Tilvi, Vithal; Hibon, Pascale; Malhotra, Sangeeta; Wang, Junxian; Veilleux, Sylvain; Swaters, Rob; Probst, Ron; Krug, Hannah; Finkelstein, Steven L; Dickinson, Mark

    2010-01-01

    Lyman alpha (Lya) emission lines should be attenuated in a neutral intergalactic medium (IGM). Therefore the visibility of Lya emitters at high redshifts can serve as a valuable probe of reionization at about the 50% level. We present an imaging search for z=7.7 Lya emitting galaxies using an ultra-narrowband filter (filter width= 9A) on the NEWFIRM imager at the Kitt Peak National Observatory. We found four candidate Lya emitters in a survey volume of 1.4 x 10^4 Mpc^3, with a line flux brighter than 6x10^-18 erg/cm^2/s (5 sigma in 2" aperture). We also performed a detailed Monte-Carlo simulation incorporating the instrumental effects to estimate the expected number of Lya emitters in our survey, and found that we should expect to detect one Lya emitter, assuming a non-evolving Lya luminosity function (LF) between z=6.5 and z=7.7. Even if one of the present candidates is spectroscopically confirmed as a z~8 Lya emitter, it would indicate that there is no significant evolution of the Lya LF from z=3.1 to z~8. ...

  20. Lyman alpha emitting galaxies at high redshift: Direct detection of young galaxies in a young universe

    Science.gov (United States)

    Dawson, Steven Arthur

    Alpha (LALA) survey. We conclude that if there is evolution in the Lya luminosity function over these epochs, its significance is below the statistical uncertainty of these data. This result supports the conclusion from several smaller samples of high-redshift Lya---emitters that the intergalactic medium remains largely reionized from the local universe out to z [approximate] 6.5. However, it is somewhat at odds with the pronounced drop in the cosmic star formation rate density recently measured between z ~ 3 and z ~ 6 in Lyman-break galaxies, and therefore potentially sheds light on the relationship between the two populations. (Abstract shortened by UMI.)

  1. The Lyman-alpha forest of a Lyman Break Galaxy VLT Spectra of MS1512-cB58 at z=2.724

    CERN Document Server

    Savaglio, S; Padovani, P

    2001-01-01

    The high redshift galaxy MS1512-cB58 (z=2.724, m_V=20.64) has been observed with the very efficient high resolution echelle spectrograph VLT/UVES. Although this is a very challenging observational program for a Southern hemisphere telescope (the galaxy is located at +36 deg declination), high resolution spectra (FWHM ~ 26 km/s) have revealed, with unprecedented detail along a galaxy sight line, the Lyman-alpha forest due to intervening clouds in the intergalactic medium (IGM). The mean depression D_A due to IGM absorption blueward of the galaxy Ly-alpha wavelength and the number density dn/dz of Ly-alpha clouds have been compared with equivalent results obtained for QSO sight lines at similar redshifts. Our results indicate a possible excess of absorption close to the galaxy. The mean depression at ~ 150 h_65^-1 Mpc comoving (Omega_m=0.3, Omega_Lambda=0.7) from the galaxy is D_A=0.36+/-0.03, to be compared with 0.22+/-0.04, expected from a best fit to QSO sight lines. In the same region (z=2.610), the number ...

  2. Radiation Transport of Heliospheric Lyman-alpha from Combined Cassini and Voyager Data Sets

    Science.gov (United States)

    Pryor, W.; Gangopadhyay, P.; Sandel, B.; Forrester, T.; Quemerais, E.; Moebius, E.; Esposito, L.; Stewart, I.; McClintock, W.; Jouchoux, A.; hide

    2008-01-01

    Heliospheric neutral hydrogen scatters solar Lyman-alpha radiation from the Sun with '27-day' intensity modulations observed near Earth due to the Sun's rotation combined with Earth's orbital motion. These modulations are increasingly damped in amplitude at larger distances from the Sun due to multiple scattering in the heliosphere, providing a diagnostic of the interplanetary neutral hydrogen density independent of instrument calibration. This paper presents Cassini data from 2003-2004 obtained downwind near Saturn at approximately 10 AU that at times show undamped '27-day' waves in good agreement with the single-scattering models of Pryor et al., 1992. Simultaneous Voyager 1 data from 2003- 2004 obtained upwind at a distance of 88.8-92.6 AU from the Sun show waves damped by a factor of -0.21. The observed degree of damping is interpreted in terms of Monte Carlo multiple-scattering calculations (e.g., Keller et al., 1981) applied to two heliospheric hydrogen two-shock density distributions (discussed in Gangopadhyay et al., 2006) calculated in the frame of the Baranov-Malama model of the solar wind interaction with the two-component (neutral hydrogen and plasma) interstellar wind (Baranov and Malama 1993, Izmodenov et al., 2001, Baranov and Izmodenov, 2006). We conclude that multiple scattering is definitely occurring in the outer heliosphere. Both models compare favorably to the data, using heliospheric neutral H densities at the termination shock of 0.085 cm(exp -3) and 0.095 cm(exp -3). This work generally agrees with earlier discussions of Voyager data in Quemerais et al., 1996 showing the importance of multiple scattering but is based on Voyager data obtained at larger distances from the Sun (with larger damping) simultaneously with Cassini data obtained closer to the Sun.

  3. The Lyman-alpha Forest Flux Distribution at z\\sim 5.2 and the Evolution of the Ionizing Background

    CERN Document Server

    McDonald, P; Donald, Patrick Mc; Miralda-Escude, Jordi

    2000-01-01

    We use the redshift evolution of the lyman-alpha forest mean transmitted flux at z>2.5 to infer the evolution of the intensity of the ionizing background, using theoretical predictions for the density distribution of the intergalactic gas giving rise to the lyman-alpha forest. The proper background intensity declines gradually with redshift, decreasing by a factor \\sim 3 between z=3 and z=5. The gravitational structure formation theory of the lyman-alpha forest implies that, given the observed mean transmitted flux of \\bar{F}=0.1 in the highest redshift quasar (with a mean lyman-alpha forest redshift z=5.2), only about 3% of the lyman-alpha spectrum should have a flux higher than 50% of the continuum, and less than 0.5% of pixels should have flux above 75% of the continuum, assuming a uniform ionizing background intensity. We show that this is consistent with the spectrum shown in Fan et al.

  4. On the Lack of Correlation Between Mg II 2796, 2803 Angstrom and Lyman alpha Emission in Lensed Star-Forming Galaxies

    Science.gov (United States)

    Rigby, Jane Rebecca; Bayliss, M. B.; Gladders, M. D.; Sharon, K.; Wuyts, E.; Dahle, H.

    2014-01-01

    We examine the Mg II 2796, 2803 Angstrom, Lyman alpha, and nebular line emission in five bright star-forming galaxies at 1.66 less than z less than 1.91 that have been gravitationally lensed by foreground galaxy clusters. All five galaxies show prominent Mg II emission and absorption in a P Cygni profile. We find no correlation between the equivalent widths of Mg II and Lyman alpha emission. The Mg II emission has a broader range of velocities than do the nebular emission line profiles; the Mg II emission is redshifted with respect to systemic by 100 to 200 km s(exp-1). When present, Lyman alpha is even more redshifted. The reddest components of Mg II and Lyman alpha emission have tails to 500-600 km s(exp-1), implying a strong outflow. The lack of correlation in the Mg II and Lyman alpha equivalent widths, the differing velocity profiles, and the high ratios of Mg II to nebular line fluxes together suggest that the bulk of Mg II emission does not ultimately arise as nebular line emission, but may instead be reprocessed stellar continuum emission.

  5. Lyman Alpha Camera for Io's SO2 atmosphere and Europa's water plumes

    Science.gov (United States)

    McEwen, Alfred S.; Sandel, Bill; Schneider, Nick

    2014-05-01

    The Student Lyman-Alpha Mapper (SLAM) was conceived for the Io Volcano Observer (IVO) mission proposal (McEwen et al., 2014) to determine the spatial and temporal variations in Io's SO2 atmosphere by recording the H Ly-α reflection over the disk (Feldman et al., 2000; Feaga et al., 2009). SO2 absorbs at H Ly-α, thereby modulating the brightness of sunlight reflected by the surface, and measures the density of the SO2 atmosphere and its variability with volcanic activity and time of day. Recently, enhancements at the Ly-α wavelength (121.57 nm) were seen near the limb of Europa and interpreted as active water plumes ~200 km high (Roth et al., 2014). We have a preliminary design for a very simple camera to image in a single bandpass at Ly-α, analogous to a simplified version of IMAGE EUV (Sandel et al. 2000). Our goal is at least 50 resolution elements across Io and/or Europa (~75 km/pixel), ~3x better than HST STIS, to be acquired at a range where the radiation noise is below 1E-4 hits/pixel/s. This goal is achieved with a Cassegrain-like telescope with a 10-cm aperture. The wavelength selection is achieved using a simple self-filtering mirror in combination with a solar-blind photocathode. A photon-counting detector based on a sealed image intensifier preserves the poisson statistics of the incoming photon flux. The intensifier window is coated with a solar-blind photocathode material (CsI). The location of each photon event is recorded by a position-sensitive anode based on crossed delay-line or wedge-and-strip technology. The sensitivity is 0.01 counts/pixel/sec/R, sufficient to estimate SO2 column abundances ranging from 1E15 to 1E17 per cm2 in a 5 min (300 sec) exposure. Sensitivity requirements to search for and image Europa plumes may be similar. Io's Ly-α brightness of ~3 kR exceeds the 0.8 kR brightness of Europa's plume reported by Roth et al. (2014), but the plume brightness is a direct measurement rather than inferring column abundance from

  6. Optical Alignment of the Chromospheric Lyman-Alpha SpectroPolarimeter using Sophisticated Methods to Minimize Activities under Vacuum

    Science.gov (United States)

    Giono, G.; Katsukawa, Y.; Ishikawa, R.; Narukage, N.; Kano, R.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.; Winebarger, A.; Kobayashi, K.

    2016-01-01

    The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding-rocket instrument developed at the National Astronomical Observatory of Japan (NAOJ) as a part of an international collaboration. The in- strument main scientific goal is to achieve polarization measurement of the Lyman-alpha line at 121.56 nm emitted from the solar upper-chromosphere and transition region with an unprecedented 0.1% accuracy. For this purpose, the optics are composed of a Cassegrain telescope coated with a "cold mirror" coating optimized for UV reflection and a dual-channel spectrograph allowing for simultaneous observation of the two orthogonal states of polarization. Although the polarization sensitivity is the most important aspect of the instrument, the spatial and spectral resolutions of the instrument are also crucial to observe the chromospheric features and resolve the Ly- pro les. A precise alignment of the optics is required to ensure the resolutions, but experiments under vacuum conditions are needed since Ly-alpha is absorbed by air, making the alignment experiments difficult. To bypass this issue, we developed methods to align the telescope and the spectrograph separately in visible light. We will explain these methods and present the results for the optical alignment of the CLASP telescope and spectrograph. We will then discuss the combined performances of both parts to derive the expected resolutions of the instrument, and compare them with the flight observations performed on September 3rd 2015.

  7. Influence of the 6^1S_0-6^3P_1 Resonance on Continuous Lyman-alpha Generation in Mercury

    CERN Document Server

    Kolbe, Daniel; Walz, Jochen

    2012-01-01

    Continuous coherent radiation in the vacuum-ultraviolet at 122 nm (Lyman-alpha) can be generated using sum-frequency mixing of three fundamental laser beams in mercury vapour. One of the fundamental beams is at 254 nm wavelength, which is close to the 6^1S_0-6^3P_1 resonance in mercury. Experiments have been performed to investigate the effect of this one-photon resonance on phasematching, absorption and the nonlinear yield. The efficiency of continuous Lyman-alpha generation has been improved by a factor of 4.5.

  8. The VIMOS Ultra Deep Survey: Lyman Alpha Emission and Stellar Populations of Star-Forming Galaxies at 2

    CERN Document Server

    Hathi, Nimish P

    2016-01-01

    The extensive ground-based spectroscopy campaign from the VIMOS Ultra-Deep Survey (VUDS), and the deep multi-wavelength photometry in three very well observed extragalactic fields (ECDFS, COSMOS, VVDS), allow us to investigate physical properties of a large sample (~4000 galaxies) of spectroscopically confirmed faint (i_{AB}20A) increases from ~10% at z~2 to ~40% at z~5-6, which is consistent with previous studies that employ higher Lyman alpha EW cut. This increase in the LAE fraction could be, in part, due to a decrease in the dust content of galaxies as redshift increases. When we compare best-fit SED estimated stellar parameters for LAEs and non-LAEs, we find that E(B-V) is smaller for LAEs at all redshifts and the difference in the median E(B-V) between LAEs and non-LAEs increases as redshift increases, from 0.05 at z~2 to 0.1 at z~3.5 to 0.2 at z~5-6. For the luminosities probed here (~L*), we find that star formation rates (SFRs) and stellar masses of galaxies, with and without Lyman alpha in emission,...

  9. Hot Gas, Cold Gas and Sub-Halos in a Lyman-alpha Blob at Redshift 2.38

    CERN Document Server

    Francis, Paul J; Colbert, James W; Palunas, Povilas; Scarlata, Claudia; Teplitz, Harry; Williger, Gerard M; Woodgate, Bruce E

    2012-01-01

    We present integral field spectroscopy of a Lyman-alpha blob at redshift 2.38, with a spectral resolution three times better than previous published work. As with previous observations, the blob has a chaotic velocity structure, much of which breaks up into multiple components. Our spectroscopy shows, however, that some of these multiple components are extremely narrow: they have velocity widths of less than 100 km/s. Combining these new data with previous observations, we argue that this Lyman-alpha blob resides in a dark-matter halo of around 10^13 solar masses. At the centre of this halo are two compact red massive galaxies. They are surrounded by hot gas, probably a super-wind from merger-induced nuclear starbursts. This hot gas has shut down star formation in the non-nuclear region of these galaxies, leading to their red-and-dead colours. A filament or lump of infalling cold gas is colliding with the hot gas phase and being shocked to high temperatures, while still around 30kpc from the red galaxies. The...

  10. A cosmic web filament revealed in Lyman-alpha emission around a luminous high-redshift quasar

    CERN Document Server

    Cantalupo, Sebastiano; Prochaska, J Xavier; Hennawi, Joseph F; Madau, Piero

    2014-01-01

    Simulations of structure formation in the Universe predict that galaxies are embedded in a "cosmic web", where the majority of baryons reside as rarefied and highly ionized gas. This material has been studied for decades in absorption against background sources, but the sparseness of these inherently one-dimensional probes preclude direct constraints on the three-dimensional morphology of the underlying web. Here we report observations of a cosmic web filament in Lyman-alpha emission, discovered during a survey for cosmic gas fluorescently "illuminated" by bright quasars at z=2.3. With a projected size of approximately 460 physical kpc, the Lyman-alpha emission surrounding the radio-quiet quasar UM287 extends well beyond the virial radius of any plausible associated dark matter halo. The estimated cold gas mass of the nebula from the observed emission is at least ten times larger than what is typically found by cosmological simulations, suggesting that a population of intergalactic gas clumps with sub-kpc siz...

  11. Lyman-$\\alpha$ Transit Spectroscopy and the Neutral Hydrogen Tail of the Hot Neptune GJ436b

    CERN Document Server

    Kulow, Jennifer R; Linsky, Jeffery; Loyd, R O Parke

    2014-01-01

    To date, more than 750 planets have been discovered orbiting stars other than the Sun. Two sub-classes of these exoplanets, "hot Jupiters" and their less massive counterparts "hot Neptunes," provide a unique opportunity to study the extended atmospheres of planets outside of our solar system. We describe here the first far-ultraviolet transit study of a hot Neptune, specifically GJ436b, for which we use HST/STIS Lyman-$\\alpha$ spectra to measure stellar flux as a function of time, observing variations due to absorption from the planetary atmosphere during transit. This analysis permits us to derive information about atmospheric extent, mass-loss rate from the planet, and interactions between the star and planet. We observe an evolution of the Lyman-$\\alpha$ lightcurve with a transit depth of GJ436b from $8.8\\pm4.5\\%$ near mid-transit, to $22.9\\pm3.9\\%$ $\\sim2$ hours after the nominal geometric egress of the planet. Using data from the time-tag mode and considering astrophysical noise from stellar variability,...

  12. Models of the Cosmological 21 cm Signal from the Epoch of Reionization Calibrated with Lyman-alpha and CMB Data

    CERN Document Server

    Kulkarni, Girish; Puchwein, Ewald; Haehnelt, Martin G

    2016-01-01

    We present here 21 cm predictions from high dynamic range simulations for a range of reionization histories that have been tested against available Lyman-alpha and CMB data. We assess the observability of the predicted spatial 21 cm fluctuations by ongoing and upcoming experiments in the late stages of reionization in the limit in which the hydrogen spin temperature is significantly larger than the CMB temperature. Models consistent with the available Lyman-alpha data and CMB measurement of the Thomson optical depth predict typical values of 10--20 mK^2 for the variance of the 21 cm brightness temperature at redshifts z=7--10 at scales accessible to ongoing and upcoming experiments (k < 1 h/cMpc). This is only a factor of a few below the sensitivity claimed to have been already reached by ongoing experiments. Our different models for the reionization history make markedly different predictions for the redshift evolution and thus frequency dependence of the 21 cm power spectrum and should be easily discerni...

  13. Probing the Rest-Frame Optical Continuum of z=4.5 Lyman Alpha Emitters with Spitzer

    Science.gov (United States)

    Finkelstein, Keely D.; Malhotra, S.; Rhoads, J. E.; Finkelstein, S. L.; Tilvi, V.; Grogin, N. A.; Pirzkal, N.; Dey, A.; Jannuzi, B. T.; Mobasher, B.; Pakzad, S.; Wang, J.

    2012-01-01

    We present the results from a deep Spitzer Space Telescope survey of more than 100 Lyman alpha emitters (LAEs) at z 4.5, first discovered in the Bootes field of the Large Area Lyman Alpha (LALA) survey. These Spitzer/IRAC observations probe the rest-frame optical continuum emission of these galaxies. We also have in hand NICMOS and WFC3 near-infrared (NIR) data from the Hubble Space Telescope (HST) of a sub-sample of these same galaxies. Of the more than 100 sources targeted with Spitzer, 15 sources are detected in at least two out of the four NICMOS/WFC3 and IRAC bands (1.1, 1.6, 3.6 and 4.5 microns), while another 40 sources are detected in one band. We will present the results from a SED-fitting analysis, using the suite of data in the observed NIR/mid-IR, coupled with deep ground based optical data. LAEs form the faint end of the galaxy luminosity function, thus most studies rely on stacking to constrain the rest-frame optical light, which can wash out variations in the physical properties in individual LAEs. This is the largest sample to date of high-redshift LAEs with measured NIR/IR fluxes, allowing us to place the most robust constraints yet on the spread of physical properties in the LAE population.

  14. Deep optical spectroscopy of extended Lyman alpha emission around three radio-quiet z=4.5 quasars

    CERN Document Server

    Courbin, F; Eigenbrod, A; Chelouche, D

    2008-01-01

    We report the first results of a spectroscopic search for Lyman alpha, envelopes around three z=4.5 radio-quiet quasars. Our observational strategy uses the FORS2 spectrograph attached to the UT1 of the Very Large Telescope (VLT) in the multi-slit mode. This allows us to observe simultaneously the quasars and several PSF stars. The spectra of the latter are used to remove the point-like quasar from the data, and to unveil the faint underlying Lyman alpha, envelopes associated with the quasars with unprecedented depth. We clearly detect an envelope around two of the three quasars. These envelopes measure respectively 10" and 13" in extent (i.e. 67 kpc and 87 kpc). This is 5 to 10 times larger than predicted by the models of Haiman & Rees (2001) and up to 100 times fainter. Our observations better agree with models involing a clumpy envelope as in Alam & Miralda-Escude (2002) or Chelouche et al. (2008). We find that the brighter quasars also have the brighter envelopes but that the extend of the envelop...

  15. Clasp/SJ Observation of Time Variations of Lyman-Alpha Emissions in a Solar Active Region

    Science.gov (United States)

    Ishikawa, S.; Kubo, M.; Katsukawa, Y.; Kano, R.; Narukage, N.; Ishikawa, R.; Bando, T.; Winebarger, A.; Kobayashi, K.; Trujillo Bueno, J.; Auchere, F.

    2016-01-01

    The Chromospheric Lyman-alpha SpectroPolarimeter (CLASP) is a sounding rocket experiment launched on September 3, 2015 to investigate the solar chromosphere, and the slit-jaw (SJ) optical system took Lya images with the high time cadence of 0.6 s. By the CLASP/SJ observation, many time variations in the solar chromosphere with the time scale of time variations and relation to the coronal structure observed by SDO/AIA. We compared the Ly(alpha) time variations at footpoints of coronal magnetic fields observed by AIA 211 Å (approx.2 MK) and AIA 171 Å (0.6 MK), and non-loop regions. As the result, we found the time variations had more in the footpoint regions. On the other hand, the time variations had no dependency on the temperature of the loop.

  16. Lyman-Alpha Emitter Galaxies at z ~ 2.8 in the Extended Chandra Deep Field-South: I. Tracing the Large-Scale Structure via Lyman-Alpha Imaging

    CERN Document Server

    Zheng, Zhen-Ya; Rhoads, James E; Finkelstein, Steven L; Wang, Jun-Xian; Jiang, Chun-Yan; Cai, Zheng

    2016-01-01

    We present a narrowband survey with three adjacent filters for z=2.8--2.9 Lyman Alpha Emitter (LAE) galaxies in the Extended Chandra Deep Field South (ECDFS), along with spectroscopic followup. With a complete sample of 96 LAEs in the narrowband NB466, we confirm a large-scale structure at z~ 2.8. Compared to the blank field in NB470 and NB475, the LAE density excess in the NB466 field is ~6.0+/-0.8 times the standard deviation expected at z~2.8, assuming a linear bias of 2. The overdense large scale structure in NB466 can be decomposed into 4 protoclusters, whose overdensities are 4.6 - 6.6. These 4 protoclusters are expected to evolve into a Coma-like cluster at z~ 0. In the meanwhile, we investigate the average star-formation rates derived from Ly{\\alpha}, rest-frame UV and X-ray, the Ly{\\alpha} luminosity functions, the Ly{\\alpha} photon densities and their dependence on the environment. We find that the Ly{\\alpha} photon density in the overdense field (NB466) is ~50\\% higher than that in the blank field ...

  17. The HETDEX Pilot Survey V: The Physical Origin of Lyman-alpha Emitters Probed by Near-infrared Spectroscopy

    CERN Document Server

    Song, Mimi; Gebhardt, Karl; Hill, Gary J; Drory, Niv; Ashby, Matthew L N; Blanc, Guillermo A; Bridge, Joanna; Chonis, Taylor; Ciardullo, Robin; Fabricius, Maximilian; Fazio, Giovanni G; Gawiser, Eric; Gronwall, Caryl; Hagen, Alex; Huang, Jia-Sheng; Jogee, Shardha; Livermore, Rachael; Salmon, Brett; Schneider, Donald P; Willner, S P; Zeimann, Gregory R

    2014-01-01

    We present the results from a VLT/SINFONI and Keck/NIRSPEC near-infrared spectroscopic survey of 16 Lyman-alpha emitters (LAEs) at $z$ = 2.1 - 2.5 in the COSMOS and GOODS-N fields discovered from the HETDEX Pilot Survey. We detect rest-frame optical nebular lines (H$\\alpha$ and/or [OIII]$\\lambda$5007) for 10 of the LAEs and measure physical properties, including the star formation rate (SFR), gas-phase metallicity, gas-mass fraction, and Ly$\\alpha$ velocity offset. We find that LAEs may lie below the mass-metallicity relation for continuum-selected star-forming galaxies at the same redshift. The LAEs all show velocity shifts of Ly$\\alpha$ relative to the systemic redshift ranging between +85 and +296 km s$^{-1}$ with a mean of +180 km s$^{-1}$. This value is smaller than measured for continuum-selected star-forming galaxies at similar redshifts. The Ly$\\alpha$ velocity offsets show a moderate correlation with the measured star formation rate (2.5$\\sigma$), but no significant correlations are seen with the SFR...

  18. Verifying the mass-metallicity relation in damped Lyman-alpha selected galaxies at 0.1

    DEFF Research Database (Denmark)

    Christensen, Lise Bech; Møller, P.; Fynbo, J. P. U.

    2014-01-01

    A scaling relation has recently been suggested to combine the galaxy mass-metallicity (MZ) relation with metallicities of damped Lyman-alpha systems (DLAs) in quasar spectra. Based on this relation the stellar masses of the absorbing galaxies can be predicted. We test this prediction by measuring...

  19. The bispectrum of the Lyman-alpha forest at z~2-2.4 from a Large sample of UVES QSO Absorption Spectra (LUQAS)

    CERN Document Server

    Viel, M; Heavens, A; Hähnelt, M G; Kim, T S; Springel, V; Hernquist, L

    2004-01-01

    We present a determination of the bispectrum of the flux in the Lyman-alpha forest of QSO absorption spectra obtained from LUQAS which consists of spectra observed with the high resolution Echelle spectrograph UVES. Typical errors on the observed bispectrum as obtained from a jack-knife estimator are ~ 50%. For wavenumbers in the range 0.03 s/km 2.

  20. Optical alignment of the Chromospheric Lyman-Alpha Spectro-Polarimeter using sophisticated methods to minimize activities under vacuum

    Science.gov (United States)

    Giono, G.; Katsukawa, Y.; Ishikawa, R.; Narukage, N.; Kano, R.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.; Winebarger, A.; Kobayashi, K.; Auchère, F.; Trujillo Bueno, J.

    2016-07-01

    The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding-rocket instrument developed at the National Astronomical Observatory of Japan (NAOJ) as a part of an international collaboration. The instrument main scientific goal is to achieve polarization measurement of the Lyman-α line at 121.56 nm emitted from the solar upper-chromosphere and transition region with an unprecedented 0.1% accuracy. The optics are composed of a Cassegrain telescope coated with a "cold mirror" coating optimized for UV reflection and a dual-channel spectrograph allowing for simultaneous observation of the two orthogonal states of polarization. Although the polarization sensitivity is the most important aspect of the instrument, the spatial and spectral resolutions of the instrument are also crucial to observe the chromospheric features and resolve the Ly-α profiles. A precise alignment of the optics is required to ensure the resolutions, but experiments under vacuum conditions are needed since Ly-α is absorbed by air, making the alignment experiments difficult. To bypass this issue, we developed methods to align the telescope and the spectrograph separately in visible light. We explain these methods and present the results for the optical alignment of the CLASP telescope and spectrograph. We then discuss the combined performances of both parts to derive the expected resolutions of the instrument, and compare them with the flight observations performed on September 3rd 2015.

  1. The effect of Lyman $\\alpha$ radiation on mini-Neptune atmospheres around M stars: application to GJ 436b

    CERN Document Server

    Miguel, Yamila; Linsky, Jeffrey L; Rugheimer, Sarah

    2014-01-01

    Mini-Neptunes orbiting M stars are a growing population of known exoplanets. Some of them are located very close to their host star, receiving large amounts of UV radiation. Many M stars emit strong chromospheric emission in the H I Lyman $\\alpha$ line (Ly$\\alpha$) at 1215.67 \\AA, the brightest far-UV emission line. We show that the effect of incoming Ly$\\alpha$ flux can significantly change the photochemistry of mini-Neptunes' atmospheres. We use GJ 436b as an example, considering different metallicities for its atmospheric composition. For solar composition, H$_2$O-mixing ratios show the largest change because of Ly$\\alpha$ radiation. H$_2$O absorbs most of this radiation, thereby shielding CH$_4$, whose dissociation is driven mainly by radiation at other far-UV wavelengths ($\\sim1300$ \\AA). H$_2$O photolysis also affects other species in the atmosphere, including H, H$_2$, CO$_2$, CO, OH and O. For an atmosphere with high metallicity, H$_2$O- and CO$_2$-mixing ratios show the biggest change, thereby shield...

  2. Deep SAURON Spectral-Imaging of the diffuse Lyman-alpha halo LAB1 in SSA22

    CERN Document Server

    Bower, R; Bacon, R; Wilman, R J; Sullivan, M; Chapman, S C; Davies, R L; De Zeeuw, P T; Emsellem, E; Bower, Richard

    2004-01-01

    We have used the SAURON panoramic integral field spectrograph to study the structure of the Ly-alpha emission-line halo, LAB1, surrounding the sub-millimeter galaxy SMM J221726+0013. This emission-line halo was discovered during a narrow-band imaging survey of the z=3.1 large-scale structure in the SSA22 region. Our observations trace the emission halo out to almost 100 kpc from the sub-millimeter source and identify two distinct Ly-alpha `mini-haloes' around the nearby Lyman-break galaxies. The main emission region has a broad line profile, with variations in the line profile seeming chaotic and lacking evidence for a coherent velocity structure. The data also suggests that Ly-alpha emission is suppressed around the sub-mm source. Interpretation of the line structure needs care because Ly-alpha may be resonantly scattered, leading to complex radiative transfer effects, and we suggest that the suppression in this region arises because of such effects. We compare the structure of the central emission-line halo...

  3. The Sherwood simulation suite: overview and data comparisons with the Lyman-alpha forest at redshifts 2 < z < 5

    CERN Document Server

    Bolton, James S; Sijacki, Debora; Haehnelt, Martin G; Kim, Tae-Sun; Meiksin, Avery; Regan, John A; Viel, Matteo

    2016-01-01

    We introduce a new set of large scale, high resolution hydrodynamical simulations of the intergalactic medium: the Sherwood simulation suite. These are performed in volumes 10^3-160^3 h^-3 comoving Mpc^{3}, span almost four orders of magnitude in mass resolution with up to 17.2 billion particles, and employ a variety of physics variations including warm dark matter and galactic outflows. We undertake a detailed comparison of the simulations to high resolution, high signal-to-noise observations of the Lyman-alpha forest over the redshift range 2 10^14.5 cm^-2 at 2 4. Finally, the temperature of intergalactic gas in the simulations may be slightly too low at z=2.7 and a flatter temperature-density relation is required at z=2.4, consistent with the expected effects of non-equilibrium ionisation during He-II reionisation.

  4. A coronagraphic absorbing cloud reveals the narrow-line region and extended Lyman-$\\alpha$ emission of QSO J0823+0529

    CERN Document Server

    Fathivavsari, Hassan; Noterdaeme, Pasquier; Pâris, Isabelle; Finley, Hayley; López, Sebastian; Srianand, Raghunathan; Sánchez, Paula

    2015-01-01

    We report long-slit spectroscopic observations of the quasar SDSS J082303.22+052907.6 ($z_{\\rm CIV}$$\\sim$3.1875), whose Broad Line Region (BLR) is partly eclipsed by a strong damped Lyman-$\\alpha$ (DLA; log$N$(HI)=21.7) cloud. This allows us to study the Narrow Line Region (NLR) of the quasar and the Lyman-$\\alpha$ emission from the host galaxy. Using CLOUDY models that explain the presence of strong NV and PV absorption together with the detection of SiII$^*$ and OI$^{**}$ absorption in the DLA, we show that the density and the distance of the cloud to the quasar are in the ranges 180 $$ $r_0$ $>$230 pc, respectively. Sizes of the neutral($\\sim$2-9pc) and highly ionized phases ($\\sim$3-80pc) are consistent with the partial coverage of the CIV broad line region by the CIV absorption from the DLA (covering factor of $\\sim$0.85). We show that the residuals are consistent with emission from the NLR with CIV/Lyman-$\\alpha$ ratios varying from 0 to 0.29 through the profile. Remarkably, we detect extended Lyman-$\\...

  5. Damped and sub-damped Lyman-alpha absorbers in z > 4 QSOs

    CERN Document Server

    Guimaraes, Rodney; De Carvalho, Reinaldo Ramos; Djorgovski, George; Noterdaeme, Pasquier; Castro, Sandra; Poppe, Paulo Da Rocha; Aghaee, Ali

    2009-01-01

    We present the results of a survey for damped (DLA, log N(H I) > 20.3) and sub-damped Lyman-? systems (19.5 2.55 along the lines-of-sight to 77 quasars with emission redshifts in the range 4 19.5 are detected of which 40 systems are damped Lyman-? systems for an absorption length of ?X = 378. About half of the lines of sight of this homogeneous survey have never been investigated for DLAs. We study the evolution with redshift of the cosmological density of the neutral gas and ?nd, consis- tently with previous studies at similar resolution, that ?DLA,H I decreases at z > 3.5. The overall cosmological evolution of ?HI shows a peak around this redshift. The H I column density distribution for log N(H I) ? 20.3 is ?tted, consistently with previous surveys, with a single power-law of index ? ? -1.8$\\pm$0.25. This power-law overpredicts data at the high-end and a second, much steeper, power-law (or a gamma function) is needed. There is a ?attening of the function at lower H I column densities with an index of ? ?...

  6. A Direct Precision Measurement of the Intergalactic Lyman-alpha Opacity at 2

    CERN Document Server

    Faucher-Giguere, C -A; Lidz, A; Hernquist, L; Zaldarriaga, M

    2007-01-01

    We directly measure the evolution of the intergalactic Lyman-alpha effective optical depth, tau_eff, over the redshift range 2 is <1% at z=2, 4% at z=3, and 12% at z=4. Previous measurements of tau_eff at 3alpha forest have generally neglected this effect and are therefore likely biased low. We provide estimates of the level of absorption arising from metals in the Ly-alpha forest based on both direct and statistical metal removal results in the literature, finding that this contribution is ~6-9% at z=3 and decreases monotonically with redshift. The high precision of our measurement, attaining 3% in redshift bins of width Delta z=0.2 aro und z=3, indicates significant departures from the best-fit power-law redshift evolution (tau_eff=0.0018(1+z)^3.92, when metals are left in), particularly near z=3.2. The observed downward departure is statistically consistent with a similar feature detected in a precision statistical measurement using Sl...

  7. Lyman-alpha Emission from a Luminous z=8.68 Galaxy: Implications for Galaxies as Tracers of Cosmic Reionization

    CERN Document Server

    Zitrin, Adi; Belli, Sirio; Bouwens, Rychard; Ellis, Richard S; Roberts-Borsani, Guido; Stark, Daniel P; Oesch, Pascal A; Smit, Renske

    2015-01-01

    We report the discovery of Lyman-alpha emission (Ly$\\alpha$) in the bright galaxy EGSY-2008532660 (hereafter EGSY8p7) using the MOSFIRE spectrograph at the Keck Observatory. First reported by Roberts-Borsani et al. (2015), it was selected for spectroscopic observations because of its photometric redshift ($z_{phot}=8.57^{+0.22}_{-0.43}$), apparent brightness (H$_{160}=25.26\\pm0.09$) and red Spitzer/IRAC [3.6]-[4.5] color indicative of contamination by strong oxygen emission in the [4.5] band. With a total integration of $\\sim4.3$ hours, our data reveal an emission line at $\\simeq11776$ {\\AA} which we argue is likely Ly$\\alpha$ at a redshift $z_{spec}=8.68$, in good agreement with the photometric estimate. The line was detected independently on two nights using different slit orientations and its detection significance is $\\sim7.5\\sigma$. An overlapping sky line contributes significantly to the uncertainty on the total line flux but not the overall significance. By direct addition and a Gaussian fit, we estima...

  8. A resolved map of the infrared excess in a Lyman Break Galaxy at z=3

    CERN Document Server

    Koprowski, M P; Geach, J E; Hine, N K; Bremer, M; Chapman, S C; Davies, L J M; Hayashino, T; Knudsen, K K; Kubo, M; Lehmer, B D; Matsuda, Y; Smith, D J B; van der Werf, P P; Violino, G; Yamada, T

    2016-01-01

    We have observed the dust continuum of ten z=3.1 Lyman Break Galaxies with the Atacama Large Millimeter/Submillimeter Array at ~450 mas resolution in Band 7. We detect and resolve the 870um emission in one of the targets with an integrated flux density of S(870)=(192+/-57) uJy, and measure a stacked 3-sigma signal of S(870)=(67+/-23) uJy for the remaining nine. The total infrared luminosities estimated from full spectral energy distribution fits are L(8-1000um)=(8.4+/-2.3)x10^10 Lsun for the detection and L(8-1000um)=(2.9+/-0.9)x10^10 Lsun for the stack. With HST ACS I-band imaging we map the rest-frame UV emission on the same scale as the dust, effectively resolving the 'infrared excess' (IRX=L_FIR/L_UV) in a normal galaxy at z=3. Integrated over the galaxy we measure IRX=0.56+/-0.15, and the galaxy-averaged UV slope is beta=-1.25+/-0.03. This puts the galaxy a factor of ~10 below the IRX-beta relation for local starburst nuclei of Meurer et al. (1999). However, IRX varies by more than a factor of 3 across t...

  9. Kinetic-Energy Distribution of D(2p) Atoms from Analysis of the D Lyman-Alpha Line Profile

    Science.gov (United States)

    Ciocca, M.; Ajello, Joseph M.; Liu, Xianming; Maki, Justin

    1997-01-01

    The kinetic-energy distribution of D(2p) atoms resulting from electron-impact dissociation of D2 has been measured. A high-resolution vacuum ultraviolet spectrometer was employed for the first measurement of the D Lyman-alpha (D L(alpha)) emission line profiles at 20- and 100-eV excitation energies. Analysis of the deconvoluted line profile of D L(alpha) at 100 eV reveals the existence of a narrow line central peak of 29+/-2 mA full width at half maximum and a broad pedestal wing structure about 190 mA wide. The wings of the line can be used to determine the fast atom distribution. The wings of D L(alpha) arise from dissociative excitation of a series of doubly excited states that cross the Franck-Condon region between 23 and 40 eV. The fast atom distribution at 100-eV electron impact energy spans the energy range from 1 to 10 eV with a peak value near 6 eV. Slow D(2p) atoms characterized by a distribution function with peak energy near 100 meV produce the central peak profile, which is nearly independent of the impact energy. The deconvoluted line profiles of the central peak at 20 eV for dissociative excitation of D2 and H2 are fitted with an analytical function for use in calibration of space flight instrumentation equipped with a D/H absorption cell. The kinetic-energy and line profile results are compared to similar measurements for H2. The absolute cross sections for the line center (slow atoms) and wings (fast atoms) and total emission line profile were measured from threshold to 400 eV. Analytical model coefficients are given for the energy dependence of the measured slow atom cross section.

  10. Continuum subtracting Lyman-alpha images: Low redshift studies using the Solar Blind Channel of HST/ACS

    CERN Document Server

    Hayes, Matthew; Mas-Hesse, J Miguel; Kunth, Daniel

    2008-01-01

    (Abridged) We are undertaking an imaging study of local star-forming galaxies in the Lyman-alpha (Lya) emission line using the Solar Blind Channel (SBC) of the ACS onboard HST. Observations have been obtained in Lya and H-alpha and six line-free continuum filters between ~1500 AA and the I-band. In a previous article Hayes et al. (2005) we demonstrated that the production of Lya line-only images (i.e. continuum subtraction) in the SBC-only data-set is non-trivial and that supporting data is a requirement. We here develop various methods of continuum subtraction and assess their relative performance for given input spectral energy distributions (SED). We show that simple assumptions about the behavior of the UV continuum consistently lead to results that are significantly in error, and determine that a spectral fitting approach is essential. Furthermore, fitting of a single component stellar or stellar+nebular spectrum is not always sufficient for realistic template SEDs and, in order to successfully recover t...

  11. On the selection of damped Lyman alpha systems using MgII absorption at 2

    CERN Document Server

    Berg, T A M; Prochaska, J X; Sanchez-Ramirez, R; Lopez, S; D'Odorico, V; Becker, G; Christensen, L; Cupani, G; Denney, K; Worseck, G

    2016-01-01

    The XQ-100 survey provides optical and near infrared coverage of 36 blindly selected, intervening damped Lyman alpha systems (DLAs) at 2 < z < 4, simultaneously covering the MgII doublet at 2796A, 2803A, and the Ly-alpha transition. Using the XQ-100 DLA sample, we investigate the completeness of selecting DLA absorbers based on their MgII rest-frame equivalent width (W2796) at these redshifts. Of the 29 DLAs with clean MgII profiles, we find that six (20% of DLAs) have W2796 < 0.6A. The DLA incidence rate of W2796 < 0.6A absorbers is a factor of ~5 higher than what is seen in z~1 samples, indicating a potential evolution in the MgII properties of DLAs with redshift. All of the W2796 < 0.6A DLAs have low metallicities (-2.5 < [M/H] < -1.7), small velocity widths (v90 < 50 km/s), and tend to have relatively low N(HI). We demonstrate that the exclusion of these low W2796 DLAs results in a higher mean N(HI) which in turn leads to a ~7% increase in the cosmological gas density of HI of DLAs...

  12. HST Emission Line Galaxies at z ~ 2: Comparing Physical Properties of Lyman Alpha and Optical Emission Line Selected Galaxies

    CERN Document Server

    Hagen, Alex; Behrens, Christoph; Ciardullo, Robin; Gebhardt, Henry S Grasshorn; Gronwall, Caryl; Bridge, Joanna S; Fox, Derek B; Schneider, Donald P; Trump, Jonathan R; Blanc, Guillermo A; Chiang, Yi-Kuan; Chonis, Taylor S; Finkelstein, Steven L; Hill, Gary J; Jogee, Shardha; Gawiser, Eric

    2015-01-01

    We compare the physical and morphological properties of z ~ 2 Lyman-alpha emitting galaxies (LAEs) identified in the HETDEX Pilot Survey and narrow band studies with those of z ~ 2 optical emission line galaxies (oELGs) identified via HST WFC3 infrared grism spectroscopy. Both sets of galaxies extend over the same range in stellar mass (7.5 < logM < 10.5), size (0.5 < R < 3.0 kpc), and star-formation rate (~1 < SFR < 100). Remarkably, a comparison of the most commonly used physical and morphological parameters -- stellar mass, half-light radius, UV slope, star formation rate, ellipticity, nearest neighbor distance, star formation surface density, specific star formation rate, [O III] luminosity, and [O III] equivalent width -- reveals no statistically significant differences between the populations. This suggests that the processes and conditions which regulate the escape of Ly-alpha from a z ~ 2 star-forming galaxy do not depend on these quantities. In particular, the lack of dependence on ...

  13. The most metal-poor damped Lyman alpha systems: An insight into dwarf galaxies at high redshift

    CERN Document Server

    Cooke, Ryan; Jorgenson, Regina A

    2014-01-01

    In this paper, we analyze the kinematics, chemistry, and physical properties of a sample of the most metal-poor damped Lyman alpha systems (DLAs), to uncover their links to modern-day galaxies. We present evidence that the DLA population as a whole exhibits a `knee' in the relative abundances of the alpha-capture and Fe-peak elements when the metallicity is [Fe/H] ~ -2.0. In this respect, the chemical evolution of DLAs is clearly different from that experienced by Milky Way halo stars, but resembles that of dwarf spheroidal galaxies in the Local Group. We also find a close correspondence between the kinematics of Local Group dwarf galaxies and of high redshift metal-poor DLAs, which further strengthens this connection. On the basis of such similarities, we propose that the most metal-poor DLAs provide us with a unique opportunity to directly study the dwarf galaxy population more than ten billion years in the past, at a time when many dwarf galaxies were forming the bulk of their stars. To this end, we have m...

  14. Polarimetry of the HI Lyman-alpha for coronal magnetic field diagnostics

    Science.gov (United States)

    Fineschi, Silvano; Hoover, Richard B.; Zukic, Muamer; Kim, Jongmin; Walker, Arthur B. C., Jr.; Baker, Phillip, C.

    1993-01-01

    We discuss and analyze the possible sources of observational and instrumental uncertainty that can be encountered in measuring magnetic fields of the solar corona through polarimetric observations of the Hanle effect of the coronal Ly-alpha line. The Hanle effect is the modification of the linear polarization of a resonantly scattered line, due to the presence of a magnetic field. Simulated observations are used to examine how polarimetric measurements of this effect are affected by the line-of-sight integration, the electron collisions, and the Ly-alpha geocorona. We plan to implement the coronal magnetic field diagnostics via the Ly-alpha Hanle effect using an all-reflecting Ly-alpha coronagraph/polarimeter (Ly-alphaCoPo) which employs reflecting multilayer mirrors, polarizers, and filters. We discuss here the requirements for such an instrument, and analyze the sources of instrumental uncertainty for polarimetric observations of the coronal Ly-alpha Hanle effect. We conclude that the anticipated polarization signal from the corona and the expected performance of the Ly-alphaCoPo instrument are such that the Ly-alpha Hanle effect method for coronal field diagnostics is feasible.

  15. Clustering of galaxies near damped Lyman-alpha systems with (z) = 2.6

    Science.gov (United States)

    Wolfe, A. M

    1993-01-01

    The galaxy two-point correlation function, xi, at (z) = 2.6 is determined by comparing the number of Ly-alpha-emitting galaxies in narrowband CCD fields selected for the presence of damped L-alpha absorption to their number in randomly selected control fields. Comparisons between the presented determination of (xi), a density-weighted volume average of xi, and model predictions for (xi) at large redshifts show that models in which the clustering pattern is fixed in proper coordinates are highly unlikely, while better agreement is obtained if the clustering pattern is fixed in comoving coordinates. Therefore, clustering of Ly-alpha-emitting galaxies around damped Ly-alpha systems at large redshifts is strong. It is concluded that the faint blue galaxies are drawn from a parent population different from normal galaxies, the presumed offspring of damped Ly-alpha systems.

  16. The intergalactic medium thermal history at redshift z=1.7--3.2 from the Lyman alpha forest: a comparison of measurements using wavelets and the flux distribution

    CERN Document Server

    Garzilli, A; Kim, T -S; Leach, S; Viel, M

    2012-01-01

    We investigate the thermal history of the intergalactic medium (IGM) in the redshift interval z=1.7--3.2 by studying the small-scale fluctuations in the Lyman alpha forest transmitted flux. We apply a wavelet filtering technique to eighteen high resolution quasar spectra obtained with the Ultraviolet and Visual Echelle Spectrograph (UVES), and compare these data to synthetic spectra drawn from a suite of hydrodynamical simulations in which the IGM thermal state and cosmological parameters are varied. From the wavelet analysis we obtain estimates of the IGM thermal state that are in good agreement with other recent, independent wavelet-based measurements. We also perform a reanalysis of the same data set using the Lyman alpha forest flux probability distribution function (PDF), which has previously been used to measure the IGM temperature-density relation. This provides an important consistency test for measurements of the IGM thermal state, as it enables a direct comparison of the constraints obtained using t...

  17. Statistical properties of damped Lyman-alpha systems from Sloan Digital Sky Survey DR12

    Science.gov (United States)

    Bird, Simeon; Garnett, Roman; Ho, Shirley

    2017-04-01

    We present new estimates for the statistical properties of damped Lyman-α absorbers (DLAs). We compute the column density distribution function at z > 2, the line density, dN/dX, and the neutral hydrogen density, ΩDLA. Our estimates are derived from the DLA catalogue of Garnett et al. (2016), which uses the Sloan Digital Sky Survey III Data Release 12 (SDSS-III DR12) quasar spectroscopic survey. This catalogue provides a probability that a given spectrum contains a DLA. It allows us to use even the noisiest data without biasing our results and thus substantially increases our sample size. We measure a non-zero column density distribution function at 95 per cent confidence for all column densities N_H I 4. We show that our results are insensitive to the signal-to-noise ratio of the spectra, but that there is a residual dependence on quasar redshift for z < 2.5, which may be due to remaining systematics in our analysis.

  18. Properties of High-Redshift Lyman Alpha Clouds II. Statistical Properties of the Clouds

    CERN Document Server

    Press, W H; Press, William H.; Rybicki, George B.

    1993-01-01

    Curve of growth analysis, applied to the Lyman series absorption ratios deduced in our previous paper, yields a measurement of the logarithmic slope of distribution of \\Lya\\ clouds in column density $N$. The observed exponential distribution of the clouds' equivalent widths $W$ is then shown to require a broad distribution of velocity parameters $b$, extending up to 80 km s$^{-1}$. We show how the exponential itself emerges in a natural way. An absolute normalization for the differential distribution of cloud numbers in $z$, $N$, and $b$ is obtained. By detailed analysis of absorption fluctuations along the line of sight we are able to put upper limits on the cloud-cloud correlation function $\\xi$ on several megaparsec length scales. We show that observed $b$ values, if thermal, are incompatible, in several different ways, with the hypothesis of equilibrium heating and ionization by a background UV flux. Either a significant component of $b$ is due to bulk motion (which we argue against on several grounds), o...

  19. Spectroscopy of z ~ 7 candidate galaxies: Using Lyman-alpha to constrain the neutral fraction of hydrogen in the high-redshift universe

    CERN Document Server

    Caruana, Joseph; Wilkins, Stephen M; Stanway, Elizabeth R; Lorenzoni, Silvio; Jarvis, Matt J; Elbert, Holly

    2013-01-01

    Following our previous spectroscopic observations of $z>7$ galaxies with Gemini/GNIRS and VLT/XSHOOTER, which targeted a total of 8 objects, we present here our results from a deeper and larger VLT/FORS2 spectroscopic sample of Wide Field Camera 3 selected $z>7$ candidate galaxies. With our FORS2 setup we cover the 737-1070nm wavelength range, enabling a search for Lyman-$\\alpha$ in the redshift range spanning 5.06 - 7.80. We target 22 $z$-band dropouts and find no evidence of Lyman-$\\alpha$ emission. The upper limits on Lyman-$\\alpha$ flux and the broad-band magnitudes are used to constrain the rest-frame Equivalent Widths for this line emission. We analyse our FORS2 observations in combination with our previous GNIRS and XSHOOTER observations, and suggest that a simple model where the fraction of high rest-frame Equivalent Width emitters follows the trend seen at $z=3-6.5$ is inconsistent with our non-detections at $z\\sim7.8$ at the 96\\% confidence level. This may indicate that a significant neutral HI frac...

  20. Lyman Alpha and MgII as Probes of Galaxies and their Environments

    CERN Document Server

    Barnes, Luke A; Kacprzak, Glenn G

    2014-01-01

    Ly{\\alpha} emission, Ly{\\alpha} absorption and MgII absorption are powerful tracers of neutral hydrogen. Hydrogen is the most abundant element in the universe and plays a central role in galaxy formation via gas accretion and outflows, as well as being the precursor to molecular clouds, the sites of star formation. Since 21cm emission from neutral hydrogen can only be directly observed in the local universe, we rely on Ly{\\alpha} emission, and Ly{\\alpha} and MgII absorption to probe the physics that drives galaxy evolution at higher redshifts. Furthermore, these tracers are sensitive to a range of hydrogen densities that cover the interstellar medium, the circumgalactic medium and the intergalactic medium, providing an invaluable means of studying gas physics in regimes where it is poorly understood. At high redshift, Ly{\\alpha} emission line searches have discovered thousands of star-forming galaxies out to z = 7. The large Ly{\\alpha} scattering cross-section makes observations of this line sensitive to even...

  1. Extended Lyman alpha haloes around individual high-redshift galaxies revealed by MUSE

    CERN Document Server

    Wisotzki, L; Blaizot, J; Brinchmann, J; Herenz, E C; Schaye, J; Bouché, N; Cantalupo, S; Contini, T; Carollo, C M; Caruana, J; Courbot, J -B; Emsellem, E; Kamann, S; Kerutt, J; Leclercq, F; Lilly, S J; Patrício, V; Sandin, C; Steinmetz, M; Straka, L A; Urrutia, T; Verhamme, A; Weilbacher, P M; Wendt, M

    2015-01-01

    We report the detection of extended Ly alpha emission around individual star-forming galaxies at redshifts z = 3-6 in an ultradeep exposure of the Hubble Deep Field South obtained with MUSE on the ESO-VLT. The data reach a limiting surface brightness (1sigma) of ~1 x 10^-19 erg s^-1 cm^-2 arcsec^-2 in azimuthally averaged radial profiles, an order of magnitude improvement over previous narrowband imaging. Our sample consists of 26 spectroscopically confirmed Ly alpha-emitting, but mostly continuum-faint (m_AB >~ 27) galaxies. In most objects the Ly alpha emission is considerably more extended than the UV continuum light. While 5 of the faintest galaxies in the sample show no significantly detected Ly alpha haloes, the derived upper limits suggest that this is just due to insufficient S/N. Ly alpha haloes therefore appear to be (nearly) ubiquitous even for low-mass (~10^8-10^9 M_sun) star-forming galaxies at z>3. We decompose the Ly alpha emission of each object into a compact `continuum-like' and an extended ...

  2. Solar H-alpha features with hot onsets. III. Long fibrils in Lyman-alpha and with ALMA

    Science.gov (United States)

    Rutten, R. J.

    2017-02-01

    In H-alpha most of the solar surface is covered by dense canopies of long opaque fibrils, but predictions for quiet-Sun observations with ALMA have ignored this fact. Comparison with Ly-alpha suggests that the extraordinary opacity of H-alpha fibrils is caused by hot precursor events. Application of a recipe that assumes momentary Saha-Boltzmann extinction during their hot onset to millimeter wavelengths suggests that ALMA will observe H-alpha-like fibril canopies, not acoustic shocks underneath, and will yield data more interesting than if these canopies were transparent. An additional file is available at the end of the PDF file of this article.This study is offered as compliment to M.W.M. de Graauw. Our ways, objects, instruments and spectral domains parted after the 1970 eclipse but converge here.

  3. Ubiquitous giant Lyman $\\alpha$ nebulae around the brightest quasars at $z\\sim3.5$ revealed with MUSE

    CERN Document Server

    Borisova, Elena; Lilly, Simon J; Marino, Raffaella A; Gallego, Sofia G; Bacon, Roland; Blaizot, Jeremy; Bouché, Nicolas; Brinchmann, Jarle; Carollo, C Marcella; Caruana, Joseph; Finley, Hayley; Herenz, Edmund C; Richard, Johan; Schaye, Joop; Straka, Lorrie A; Turner, Monica L; Urrutia, Tanya; Verhamme, Anne; Wisotzki, Lutz

    2016-01-01

    Direct Lyman a imaging of fluorescent emission from intergalactic gas at z~2 has recently revealed giant cosmological structures around luminous quasars with unexpected physical properties, e.g. the Slug Nebula (Cantalupo et al. 2014). Despite their high luminosity, the detection rate of such systems in narrow-band and spectroscopic surveys is very low, i.e. less than 10%. If intrinsic and not due to observational limitations, such a low detection frequency would encode crucial information on the distribution and properties of cold gas around quasars, their emission opening angle and duty cycle. In this study, we exploit the unique capabilities of the MUSE ESO/VLT to perform a blind survey for giant Ly $\\alpha$ nebulae around 17 of the brightest radio-quiet quasars at 3

  4. HST/ACS Morphology of Lyman Alpha Emitters at Redshift 5.7 in the COSMOS Field

    CERN Document Server

    Taniguchi, Y; Scoville, N Z; Sasaki, S S; Nagao, T; Shioya, Y; Saitô, T; Ideue, Y; Nakajima, A; Matsuoka, K; Sanders, D B; Mobasher, B; Aussel, H; Capak, P; Salvato, M; Koekemoer, A; Carilli, C; Cimatti, A; Ellis, Richard S; Garilli, B; Giavalisco, M; Ilbert, O; Impey, C D; Kitzbichler, M G; Le Fèvre, O; McCracken, H J; Scarlata, C; Schinnerer, E; Smolcic, V; Tribiano, S; Trump, J R

    2009-01-01

    We present detailed morphological properties of Lyman alpha emitters (LAEs) at z~ 5.7 in the COSMOS field, based on {\\it Hubble Space Telescope} Advanced Camera for Surveys (ACS) data. The ACS imaging in the F814W filter covered 85 LAEs of the 119 LAEs identified in the full two square degree field, and 47 LAEs of them are detected in the ACS images. Nearly half of them are spatially extended with a size larger than 0.15 arcsec (~0.88 kpc at z=5.7) up to 0.4 arcsec (~2.5 kpc at z=5.7). The others are nearly unresolved compact objects. Two LAEs show double-component structures, indicating interaction or merging of building components to form more massive galaxies. By stacking the ACS images of all the detected sources, we obtain a Sersic parameter of n~0.7 with a half-light radius of 0.13 arcsec (0.76 kpc), suggesting that the majority of ACS detected LAEs have not spheroidal-like but disk-like or irregular light profiles. Comparing ACS F814W magnitudes (I_814) with Subaru/Suprime-Cam magnitudes in the NB816, ...

  5. The transverse proximity effect in the z ~ 2 Lyman-alpha forest suggests QSO episodic lifetimes of ~1 Myr

    CERN Document Server

    Kirkman, David

    2008-01-01

    We look for signs of the H~I transverse proximity effect in the spectra of 130 QSO pairs, most with transverse separations in the plane of the sky of 0.1 -- 3 Mpc at z ~ 2.2. We expected to see a decrease in Lyman-alpha forest HI absorption in the spectrum of background QSOs near the position of foreground QSOs. Instead we see no change in the absorption in front of the foreground QSOs, and we see evidence for a 50% increase in the absorption out to 6 Mpc behind the foreground QSOs. Further, we see no change in the H I absorption along the line-of-sight to the foreground QSOs, the normal line-of-sight proximity effect. We may account for the lack of change in the H I absorption if the effect of extra UV photons is canceled by higher gas density around QSOs. If so, the increase in absorption behind the QSOs then suggests that the higher gas density there is not canceled by the UV radiation from the QSOs. We can explain our observations if QSOs have had their current UV luminosities for less than approximately ...

  6. High-ion absorption in the proximate damped Lyman-alpha system toward Q0841+129

    CERN Document Server

    Fox, Andrew J; Petitjean, Patrick; Srianand, Raghunathan; Guimarães, Rodney

    2011-01-01

    We present VLT/UVES spectroscopy of the quasar Q0841+129, whose spectrum shows a proximate damped Lyman-alpha (PDLA) absorber at z=2.47621 and a proximate sub-DLA at z=2.50620, both lying close in redshift to the QSO itself at z_em=2.49510+/-0.00003. This fortuitous arrangement, with the sub-DLA acting as a filter that hardens the QSO's ionizing radiation field, allows us to model the ionization level in the foreground PDLA, and provides an interesting case-study on the origin of the high-ion absorption lines Si IV, C IV, and O VI in DLAs. The high ions in the PDLA show at least five components spanning a total velocity extent of ~160 km/s, whereas the low ions exist predominantly in a single component spanning just 30 km/s. We examine various models for the origin of the high ions. Both photoionization and turbulent mixing layer models are fairly successful at reproducing the observed ionic ratios after correcting for the non-solar relative abundance pattern, though neither model can explain all five compone...

  7. Detection of Diffuse Interstellar Bands in the z=0.5 Damped Lyman alpha system towards AO 0235+164

    CERN Document Server

    York, B A; Lawton, B; Churchill, C W; Snow, T P; Johnson, R A; Ryan, S G; York, Brian A.; Ellison, Sara L.; Lawton, Brandon; Churchill, Christopher W.; Snow, Theodore P.; Johnson, Rachel A.; Ryan, Sean G.

    2006-01-01

    We report the first detection of the 5705 and 5780 A Diffuse Interstellar Bands (DIBs) in a moderate redshift Damped Lyman alpha (DLA) system. We measure a rest frame equivalent width of 63.2 +- 8.7 mA for the 5705 and 216+-9 mA for the 5780 A feature in the z_abs 0.524 DLA towards AO 0235+164 and derive limits for the equivalent widths of the bands at 5797, 6284, and 6613 A. The equivalent width of the 5780 band is lower than would be expected based on the Galactic correlation of DIB strength with N(HI), but is in good agreement with the correlation with E(B-V). The relative strengths of the 5780 and 6284 A DIBs are inconsistent with all Galactic and extragalactic sightlines, except one Small Magellanic Cloud wing sightline towards Sk 143. However, the relative strengths of the 5705 and 5780 A DIBs are consistent with the Galactic relation, indicating that the relative strengths of these bands may be less sensitive to environment or that they may be associated with a similar carrier. The detection of DIBs at...

  8. Probing the Circumgalactic Medium at High-Redshift Using Composite BOSS Spectra of Strong Lyman-alpha Forest Absorbers

    CERN Document Server

    Pieri, Matthew M; Frank, Stephan; Crighton, Neil; Weinberg, David H; Lee, Khee-Gan; Noterdaeme, Pasquier; Bailey, Stephen J; Busca, Nicolas; Ge, Jian; Kirkby, David; Lundgren, Britt; Mathur, Smita; Paris, Isabelle; Palanque-Delabrouille, Nathalie; Petitjean, Patrick; Rich, James; Ross, Nicholas P; Schneider, Donald P; York, Donald G

    2013-01-01

    We present composite spectra constructed from a sample of 242,150 Lyman-alpha (Lya) forest absorbers at redshifts 2.4

  9. Determination of Coronal Mass Ejection physical parameters from combination of polarized visible light and UV Lyman-$\\alpha$ observations

    CERN Document Server

    Susino, R

    2016-01-01

    Visible-light observations of Coronal Mass Ejections (CMEs) performed with coronagraphs and heliospheric imagers (in primis on board the SOHO and STEREO missions) have offered so far the best way to study the kinematics and geometrical structure of these fundamental events. Nevertheless, it has been widely demonstrated that only combination of multi-wavelength data (including X-ray spectra, EUV images, EUV-UV spectra, and radio dynamic spectra) can provide complete information on the plasma temperature and density distributions, non-thermal motions, magnetic fields, and other physical parameters, for both CMEs and CME-related phenomena. In this work, we analyze three CMEs by combining simultaneous data acquired in the polarized visible light by the LASCO-C2 coronagraph and in the UV H I Lyman-$\\alpha$ line (1216 \\AA) by the UVCS spectrometer, in order to estimate the CME plasma electron density (using the polarization-ratio technique to infer the 3D structure of the CME) and temperature (from the comparison b...

  10. Cosmological and astrophysical parameters from the SDSS flux power spectrum and hydrodynamical simulations of the Lyman-alpha forest

    CERN Document Server

    Viel, M; Viel, Matteo; Haehnelt, Martin G.

    2006-01-01

    (abridged) The flux power spectrum of the Lyman-alpha forest in quasar (QSO) absorption spectra is sensitive to a wide range of cosmological and astrophysical parameters and instrumental effects. Modelling the flux power spectrum in this large parameter space to an accuracy comparable to the statistical uncertainty of large samples of QSO spectra is very challenging. We use here a coarse grid of hydrodynamical simulations run with GADGET-2 to obtain a ``best guess'' model around which we calculate a finer grid of flux power spectra using a Taylor expansion of the flux power spectrum to first order. We find that the SDSS flux power spectrum alone is able to constrain a wide range of parameters including the amplitude of the matter power spectrum sigma_8, the matter density Omega_m, the spectral index of primordial density fluctuations n, the effective optical depth tau_eff and its evolution. The thermal history of the Intergalactic Medium (IGM) is, however, poorly constrained and the SDSS data favour either an...

  11. Escape of about five per cent of Lyman-alpha photons from high-redshift star-forming galaxies.

    Science.gov (United States)

    Hayes, Matthew; Ostlin, Göran; Schaerer, Daniel; Mas-Hesse, J Miguel; Leitherer, Claus; Atek, Hakim; Kunth, Daniel; Verhamme, Anne; de Barros, Stéphane; Melinder, Jens

    2010-03-25

    The Lyman-alpha (Lyalpha) emission line is the primary observational signature of star-forming galaxies at the highest redshifts, and has enabled the compilation of large samples of galaxies with which to study cosmic evolution. The resonant nature of the line, however, means that Lyalpha photons scatter in the neutral interstellar medium of their host galaxies, and their sensitivity to absorption by interstellar dust may therefore be greatly enhanced. This implies that the Lyalpha luminosity may be significantly reduced, or even completely suppressed. Hitherto, no unbiased empirical test of the escaping fraction (f(esc)) of Lyalpha photons has been performed at high redshifts. Here we report that the average f(esc) from star-forming galaxies at redshift z = 2.2 is just 5 per cent by performing a blind narrowband survey in Lyalpha and Halpha. This implies that numerous conclusions based on Lyalpha-selected samples will require upwards revision by an order of magnitude and we provide a benchmark for this revision. We demonstrate that almost 90 per cent of star-forming galaxies emit insufficient Lyalpha to be detected by standard selection criteria. Both samples show an anti-correlation of f(esc) with dust content, and we show that Lyalpha- and Halpha-selection recovers populations that differ substantially in dust content and f(esc).

  12. 9.7 micrometer Silicate Absorption in a Damped Lyman-alpha Absorber at z=0.52

    CERN Document Server

    Kulkarni, Varsha P; Vladilo, Giovanni; Welty, Daniel E

    2007-01-01

    We report a detection of the 9.7 micrometer silicate absorption feature in a damped Lyman-alpha (DLA) system at z_{abs} = 0.524 toward AO0235+164, using the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope. The feature shows a broad shallow profile over about 8-12 micrometers in the absorber rest frame and appears to be > 15 sigma significant in equivalent width. The feature is fit reasonably well by the silicate absorption profiles for laboratory amorphous olivine or diffuse Galactic interstellar clouds. To our knowledge, this is the first indication of 9.7 micrometer silicate absorption in a DLA. We discuss potential implications of this finding for the nature of the dust in quasar absorbers. Although the feature is relatively shallow (tau_{9.7} = 0.08-0.09), it is about 2 times deeper than expected from extrapolation of the tau_{9.7} vs. E(B-V) relation known for diffuse Galactic interstellar clouds. Further studies of the 9.7 micrometer silicate feature in quasar absorbers will open a new w...

  13. Low redshift Lyman alpha absorption lines and the dark matter halos of disk galaxies

    Science.gov (United States)

    Maloney, Philip

    1993-01-01

    Recent observations using the Hubble Space Telescope of the z = 0.156 QSO 3C 273 have discovered a surprisingly large number of Ly-alpha absorption lines. In particular, Morris et al. found 9 certain and 7 possible Ly-alpha lines with equivalent widths above 25 mA. This is much larger (by a factor of 5-10) than the number expected from extrapolation of the high-redshift behavior of the Ly-alpha forest. Within the context of pressure-confined models for the Ly-alpha clouds, this behavior can be understood if the ionizing background declines sharply between z is approximately 2 and z is approximately 0. However, this requires that the ionizing photon flux drop as rapidly as the QSO volume emissivity; moreover, the absorbers must have a space density n(sub O) is approximately 2.6(N/10)h/((D/100 kpc)(sup 2)) Mpc(sup -3) where D is the present-day diameter of the absorbers. It is somewhat surprising that such necessarily fragile objects could have survived in such numbers to the present day. It is shown that it is plausible that the atomic hydrogen extents of spiral and irregular galaxies are large enough to produce the observed number of Ly-alpha absorption lines toward 3C 273, and that the neutral column densities and doppler b-values expected under these conditions fall in the range found by Morris et al. (1991).

  14. The nature of z ~ 2.3 Lyman-alpha emitters

    CERN Document Server

    Nilsson, Kim K; Møller, Palle; Möller-Nilsson, Ole; Tapken, Christian; Freudling, Wolfram; Fynbo, Johan P U

    2010-01-01

    We study the multi-wavelength properties of a set of 171 Ly-alpha emitting candidates at redshift z = 2.25 found in the COSMOS field. The candidates are shown to have different properties from those of Ly-alpha emitters found at higher redshift, by fitting the spectral energy distributions (SEDs) using a Monte-Carlo Markov-Chain technique and including nebular emission in the spectra. The dust contents and stellar masses are both higher, with A_V = 0.0 - 2.0 mag and stellar masses in the range log M_* = 9.0 - 11.0 M_sun. Young population ages are well constrained, but older population ages are typically unconstrained. In 40 % of the galaxies only a single, young population of stars is observed. We show that the ages and Ly-alpha fluxes of the best fit galaxies are correlated with their dust properties, with higher dust extinction in younger galaxies. We conclude that the stellar properties of Ly-alpha emitters at z = 2.25 are different from those at higher redshift and that they are very diverse. Ly-alpha sel...

  15. Lyman {\\alpha} radiative transfer in the high-redshift, dusty Universe

    CERN Document Server

    Laursen, Peter

    2010-01-01

    The significance of the Ly{\\alpha} emission line as a probe of the high-redshift Universe has long been established. Originating mainly in the vicinity of young, massive stars and in association with accretion of large bulks of matter, it is ideal for detecting young galaxies, the fundamental building blocks of our Universe. Since many different processes shape the spectrum and the spatial distribution of the Ly{\\alpha} photons in various ways, a multitude of physical properties of galaxies can be unveiled. However, this also makes the interpretation of Ly{\\alpha} observations notoriously difficult. Because Ly{\\alpha} is a resonant line, it scatters on neutral hydrogen, having its path length from the source to our telescopes vastly increased, and taking it through regions of unknown physical conditions. In this work, a numerical code capable of calculating realistically the radiative transfer of Ly{\\alpha} is presented. The code is capable of performing the radiative transfer in an arbitrary and adaptively r...

  16. Evidence for a direct collapse black hole in the Lyman-alpha source CR7

    CERN Document Server

    Smith, Aaron; Loeb, Abraham

    2016-01-01

    Throughout the epoch of reionization the most luminous Ly{\\alpha} emitters are capable of ionizing their own local bubbles. The CR7 galaxy at $z \\approx 6.6$ stands out for its combination of exceptionally bright Ly{\\alpha} and HeII 1640 Angstrom line emission but absence of metal lines. As a result CR7 may be the first viable candidate host of a young primordial starburst or direct collapse black hole. High-resolution spectroscopy reveals a +160 km s$^{-1}$ velocity offset between the Ly{\\alpha} and HeII line peaks while the spatial extent of the Ly{\\alpha} emitting region is $\\sim 16$ kpc. The observables are indicative of an outflow signature produced by a strong central source. We present one-dimensional radiation-hydrodynamics simulations incorporating accurate Ly{\\alpha} feedback and ionizing radiation to investigate the nature of the CR7 source. We find that a Population III star cluster with $10^5$ K blackbody emission ionizes its environment too efficiently to generate a significant velocity offset. ...

  17. The evolution of superbubbles and the detection of Lyman $\\alpha$ in star-forming galaxies

    CERN Document Server

    Tenorio-Tagle, G; Kunth, D; Terlevich, E; Terlevich, R J; Tenorio-Tagle, Guillermo; Silich, Sergey A.; Kunth, Daniel; Terlevich, Elena; Terlevich, Roberto

    1999-01-01

    The detection of Ly alpha emission in star-forming galaxies in different shapes and intensities (always smaller than predicted for case B recombination) has puzzled the astronomical community for more than a decade. Here we use two dimensional calculations to follow the evolution of superbubbles and of the H II regions generated by the output of UV photons from massive stars. We show the impact caused by massive star formation in the ISM of different galaxies and we look at the conditions required to detect Ly alpha emission from a nuclear H II region, and the variety of profiles that may be expected as a function of time.

  18. Large-scale clustering of Lyman-alpha emission intensity from SDSS/BOSS

    CERN Document Server

    Croft, Rupert A C; Zheng, Zheng; Bolton, Adam; Dawson, Kyle S; Peterson, Jeffrey B; York, Donald G; Eisenstein, Daniel; Brinkmann, Jon; Brownstein, Joel; Delubac, Timothée; Font-Ribera, Andreu; Hamilton, Jean-Christophe; Lee, Khee-Gan; Myers, Adam; Palanque-Delabrouille, Nathalie; Pâris, Isabelle; Petitjean, Patrick; Pieri, Matthew M; Ross, Nicholas P; Rossi, Graziano; Schlegel, David J; Schneider, Donald P; Slosar, Anže; Vazquez, José; Viel, Matteo; Weinberg, David H; Yèche, Christophe

    2015-01-01

    (Abridged) We detect the large-scale structure of Lya emission in the Universe at redshifts z=2-3.5 by measuring the cross-correlation of Lya surface brightness with quasars in SDSS/BOSS. We use a million spectra targeting Luminous Red Galaxies at z, the amplitude of mass fluctuations, and the quasar and Lya emission bias factors. Using known values, we infer (b_alpha/3) = (3.9 +/- 0.9) x 10^-21 erg/s cm^-2 A^-1 arcsec^-2, where b_alpha is the Lya emission bias factor. If the dominant sources of Lya emission are star forming galaxies, we infer rho_SFR = (0.28 +/- 0.07) (3/b_alpha) /yr/Mpc^3 at z=2-3.5. For b_alpha=3, this value is a factor of 21-35 above previous estimates from individually detected Lya emitters, although consistent with the total rho_SFR derived from dust-corrected, continuum UV surveys. 97% of the Lya emission in the Universe at these redshifts is therefore undetected in previous surveys of Lya emitters. Our measurement is much greater than seen from stacking analyses of faint halos surroun...

  19. C IV and He II Line Emission of Lyman Alpha Blobs: Powered by Shock Heated Gas

    CERN Document Server

    Cabot, Samuel H C; Zheng, Zheng

    2016-01-01

    Utilizing {\\it ab initio} ultra-high resolution hydrodynamical simulations, we investigate the properties of the interstellar and circum-galactic medium of Ly$\\alpha$ Blobs (LABs) at $z=3$, focusing on three important emission lines: Ly$\\alpha$ 1216\\AA, \\heii 1640\\AA\\ and \\civ 1449\\AA. Their relative strengths provide a powerful probe of the thermodynamic properties of the gas when confronted with observations. By adjusting the dust attenuation effect using one parameter and matching the observed size-luminosity relation of LABs using another parameter, we show that our simulations can reproduce the observed \\civ/\\lya\\ and \\heii/\\lya\\ ratios adequately. This analysis provides the first successful physical model to account for simultaneously the LAB luminosity function, luminosity-size relation, and the \\civ/Ly$\\alpha$ and \\heii/Ly$\\alpha$ ratios, with only two parameters. The physical underpinning for this model is that, in addition to the stellar component for the \\lya\\ emission, the \\lya\\ and \\civ\\ emission...

  20. arXiv Neutrino masses and cosmology with Lyman-alpha forest power spectrum

    CERN Document Server

    Palanque-Delabrouille, Nathalie; Baur, Julien; Magneville, Christophe; Rossi, Graziano; Lesgourgues, Julien; Borde, Arnaud; Burtin, Etienne; LeGoff, Jean-Marc; Rich, James; Viel, Matteo; Weinberg, David

    2015-01-01

    We present constraints on neutrino masses, the primordial fluctuation spectrum from inflation, and other parameters of the $\\Lambda$CDM model, using the one-dimensional Ly$\\alpha$-forest power spectrum measured by Palanque-Delabrouille et al. (2013) from SDSS-III/BOSS, complemented by Planck 2015 cosmic microwave background (CMB) data and other cosmological probes. This paper improves on the previous analysis by Palanque-Delabrouille et al. (2015) by using a more powerful set of calibrating hydrodynamical simulations that reduces uncertainties associated with resolution and box size, by adopting a more flexible set of nuisance parameters for describing the evolution of the intergalactic medium, by including additional freedom to account for systematic uncertainties, and by using Planck 2015 constraints in place of Planck 2013. Fitting Ly$\\alpha$ data alone leads to cosmological parameters in excellent agreement with the values derived independently from CMB data, except for a weak tension on the scalar index ...

  1. The Signatures of Large-scale Temperature Fluctuations in the Lyman-alpha Forest

    CERN Document Server

    McQuinn, Matthew; Lidz, Adam; Zaldarriaga, Matias

    2010-01-01

    It appears inevitable that reionization processes would have produced large-scale temperature fluctuations in the intergalactic medium. Using toy temperature models and detailed heating histories in cosmological simulations of HeII reionization, we study the consequences of inhomogeneous heating for the Ly-alpha forest. The impact of temperature fluctuations in physically well-motivated models can be surprisingly subtle. In fact, we show that temperature fluctuations at the level predicted by our reionization simulations do not give rise to detectable signatures in the types of statistics that have been employed previously. However, because of the aliasing of small-scale density power to larger scale modes in the line-of-sight Ly-alpha forest power spectrum, earlier analyses were not sensitive to 3D modes with >~ 30 comoving Mpc wavelengths -- scales where temperature fluctuations are likely to be relatively largest. The ongoing Baryon Oscillation Spectroscopic Survey (BOSS) aims to measure the 3D power spect...

  2. The lack of intense Lyman~alpha in ultradeep spectra of z=7 candidates in GOODS-S: imprint of reionization?

    CERN Document Server

    Fontana, A; Pentericci, L; Castellano, M; Giavalisco, M; Grazian, A; Boutsia, K; Cristiani, S; Dickinson, M; Giallongo, E; Maiolino, M; Moorwood, A; Santini, P

    2010-01-01

    We present ultradeep optical spectroscopy obtained with FORS2 on VLT of seven Lyman-break galaxy (LBG) candidates at z>6.5 selected in the GOODS-S field from Hawk-I/VLT and WFC3/HST imaging. For one galaxy we detect a low significance emission line (S/N10 is ~ 2%, and that of observing only one galaxy out of seven with S/N=5 is ~4%, but these can be as small as ~1E-3, depending on the details of the EW distribution. We conclude that either a significant fraction of the candidates is not at high redshift or that some physical mechanism quenches the Lyman alpha emission emerging from the galaxies at z>6.5, abruptly reversing the trend of the increasing fraction of strong emitters with increasing redshift observed up to z~ 6.5. We discuss the possibility that an increasingly neutral intergalactic medium is responsible for such quenching.

  3. The VLT LBG Redshift Survey - V. Characterising the z = 3.1 Lyman Alpha Emitter Population

    CERN Document Server

    Bielby, R M; Shanks, T; Francke, H; Crighton, N H M; Bañados, E; González-López, Jorge; Infante, L; Orsi, A

    2016-01-01

    We present a survey of Ly$\\alpha$ emitting galaxies in the fields of the VLT LBG Redshift Survey, incorporating the analysis of narrow band number counts, the rest frame UV luminosity function and the two-point correlation function of Ly$\\alpha$ emitters at $z\\approx3.1$. Our photometric sample consists of 750 LAE candidates, over an area of 1.07 deg$^2$, with estimated equivalent widths of $\\gtrsim65$ \\AA, from 5 fields based on deep Subaru Suprime-Cam imaging data. Added to this we have obtained spectroscopic follow-up observations, which successfully detected Ly$\\alpha$ emission in 35 galaxies. Based on the spectroscopic results, we refined our photometric selection constraints, with the resulting sample having a success rate of $78\\pm18\\%$. We calculate the narrow band number counts for our photometric sample and find these to be consistent with previous studies of LAEs at this redshift. We find the $R$-band continuum luminosity function to be $\\sim10\\times$ lower than the equivalent luminosity function o...

  4. Modeling Lyman-\\alpha\\ Forest Cross-Correlations with LyMAS

    CERN Document Server

    Lochhaas, Cassandra; Peirani, Sébastien; Dubois, Yohan; Colombi, Stéphane; Blaizot, Jérémy; Font-Ribera, Andreu; Pichon, Christophe; Devriendt, Julien

    2015-01-01

    We use the Ly-$\\alpha$ Mass Association Scheme (LyMAS; Peirani et al. 2014) to predict cross-correlations at z = 2.5 between dark matter halos and transmitted flux in the Ly-$\\alpha$ forest, and we compare these predictions to cross-correlations measured for quasars and damped Ly-$\\alpha$ systems (DLAs) from the Baryon Oscillation Spectroscopic Survey (BOSS) by Font-Ribera et al. (2012, 2013). We calibrate and test LyMAS using Horizon-AGN hydrodynamical cosmological simulations of a $(100\\ h^{-1}\\ \\rm{Mpc})^3$ comoving volume with and without AGN feedback. We apply this calibration to a $(1\\ h^{-1}\\ \\rm{Gpc})^3$ simulation realized with $2048^3$ dark matter particles for our primary predictions. In the $100\\ h^{-1}\\ \\rm{Mpc}$ box, LyMAS reproduces the halo-flux correlations computed from the full hydrodynamic gas distribution essentially perfectly. In the $1\\ h^{-1}\\ \\rm{Gpc}$ box, the amplitude of the cross-correlation tracks the halo bias as expected, and the correlation for a halo sample with a distributio...

  5. Strong Field-to-Field Variation of Lyman alpha Nebulae Populations at z~2.3

    CERN Document Server

    Yang, Yujin; Eisenstein, Daniel; Davé, Romeel

    2010-01-01

    Understanding the nature of distant Ly-alpha nebulae ("blobs") and connecting them to their present-day descendants requires constraining their number density, clustering, and large-scale environment. To measure these basic quantities, we conduct a deep narrowband imaging survey in four different fields, Chandra Deep Field South (CDFS), Chandra Deep Field North, and two COSMOS subfields, for a total survey area of 1.2deg^2. We discover 25 blobs at z=2.3 with Ly-alpha luminosities of 0.7-8x10^43 erg/s and isophotal areas of Aiso = 10-60 arcsec^2. The transition from compact Ly-alpha emitters (Aiso ~ a few arcsec^2) to extended blobs (Aiso > 10 arcsec^2) is continuous, suggesting a single family perhaps governed by similar emission mechanisms. Surprisingly, most blobs (16/25) are in one survey field, the CDFS. The six brightest, largest blobs with L > 1.5x10^43 erg/s and Aiso > 16 arcsec^2 lie only in the CDFS. These large, bright blobs have a field-to-field variance of sigma_v >~ 1.5 (150%) about their number ...

  6. Minihalo Model for the Low-Redshift Lyman alpha Absorbers Revisited

    Directory of Open Access Journals (Sweden)

    Lalović, A.

    2008-06-01

    Full Text Available We reconsider the basic properties of the classical minihalo model of Rees and Milgrom in light of the new work, both observational (on "dark galaxies" and masses of baryonic haloes and theoretical (on the cosmological mass function and the history of star formation. In particular, we show that more detailed models of ionized gas in haloes of dark matter following isothermal and Navarro-Frenk-White density profile can effectively reproduce particular aspects of the observed column density distribution function in a heterogeneous sample of low-and intermediate-redshift Ly$alpha$ forest absorption lines.

  7. Chemical enrichment of Damped Lyman Alpha systems as a direct constraint on Population III star formation

    CERN Document Server

    Kulkarni, Girish; Hennawi, Joseph F; Vangioni, Elisabeth

    2013-01-01

    Damped Ly-alpha absorbers (DLAs) can be used to measure gas-phase metallicities at large cosmological lookback times with high precision. Relative abundances can still be measured accurately deep into the reionization epoch (z > 6) using transitions redward of Ly-alpha. Here we study chemical evolution of DLAs using a constrained model for evolution of galaxies and IGM to determine the degree to which DLA abundance measurements can probe Population III enrichment. We find that if the critical metallicity of Population III to II transition is 5. Thus, a sample of DLA abundance measurements at high redshift holds the promise to constrain Population III IMF. A sample of just 10 DLAs with relative abundances measured to an accuracy of 0.1 dex is sufficient to constrain the Population III IMF at 4-sigma. These constraints may prove stronger than other probes such as metal-poor stars and individual DLAs. Our results provide a global picture of the cosmic thermal, ionization, and chemical evolution, and can rule ou...

  8. The average submillimetre properties of Lyman-alpha Blobs at z=3

    CERN Document Server

    Hine, N K; Matsuda, Y; Lehmer, B D; Michalowski, M J; Farrah, D; Spaans, M; Oliver, S J; Smith, D J B; Chapman, S C; Jenness, T; Alexander, D M; Robson, I; van der Werf, P

    2016-01-01

    Ly-alpha blobs (LABs) offer insight into the complex interface between galaxies and their circumgalactic medium. Whilst some LABs have been found to contain luminous star-forming galaxies and active galactic nuclei that could potentially power the Ly-alpha emission, others appear not to be associated with obvious luminous galaxy counterparts. It has been speculated that LABs may be powered by cold gas streaming on to a central galaxy, providing an opportunity to directly observe the `cold accretion' mode of galaxy growth. Star-forming galaxies in LABs could be dust obscured and therefore detectable only at longer wavelengths. We stack deep SCUBA-2 observations of the SSA22 field to determine the average 850um flux density of 34 LABs. We measure S_850 = 0.6 +/- 0.2mJy for all LABs, but stacking the LABs by size indicates that only the largest third (area > 1794 kpc^2) have a mean detection, at 4.5 sigma, with S_850 = 1.4 +/- 0.3mJy. Only two LABs (1 and 18) have individual SCUBA-2 > 3.5 sigma detections at a d...

  9. The Properties of Lyman Alpha Nebulae: Gas Kinematics from Non-resonant Lines

    CERN Document Server

    Yang, Yujin; Jahnke, Knud; Davé, Romeel

    2014-01-01

    [Abridged] With VLT/X-shooter, we obtain optical and NIR spectra of six Ly-alpha blobs at z~2.3. Using three measures --- the velocity offset between the Lya line and the non-resonant [OIII] or H-alpha line (Dv_Lya), the offset of stacked interstellar metal absorption lines, and the spectrally-resolved [OIII] line profile --- we study the kinematics of gas along the line of sight to galaxies within each blob center. These three indicators generally agree in velocity and direction, and are consistent with a simple picture in which the gas is stationary or slowly outflowing at a few hundred km/s from the embedded galaxies. The absence of stronger outflows is not a projection effect: the covering fraction for our sample is limited to <1/8 (13%). The outflow velocities exclude models in which star formation or AGN produce "super" or "hyper" winds of up to ~1000km/s. The Dv_Lya offsets here are smaller than typical of LBGs, but similar to those of compact LAEs. The latter suggests that outflow speed cannot be a...

  10. The clustering of Lyman alpha emitters at z=7: implications for reionization and host halo masses

    CERN Document Server

    Sobacchi, Emanuele

    2015-01-01

    The Ly$\\alpha$ line of high-redshift galaxies has emerged as a powerful probe of both early galaxy evolution and the epoch of reionization (EoR). Motivated by the upcoming wide-field survey with the Subaru Hyper Supreme-Cam (HSC), we study the angular correlation function (ACF) of narrow-band selected, $z\\approx7$ LAEs. The clustering of LAEs is determined by both: (i) their typical host halo masses, $\\bar{M}_{\\rm h}$; (ii) the absorption due to a patchy EoR, characterized by an average neutral fraction of the IGM, $\\bar{x}_{\\rm HI}$. We bracket the allowed LAE ACF by exploring extreme scenarios for both the intrinsic Ly$\\alpha$ emission and the morphology of cosmic ionized patches in physical EoR models. Current LAE ACF measurements imply that the Universe is mostly ionized at $z\\approx7$, with $\\bar{x}_{\\rm HI}\\lesssim0.5$ (1-$\\sigma$) even for an extremely conservative model of intrinsic emission. The upcoming Ultra Deep campaign with the HSC could improve on these constraints by tens of percent, or $\\bar{...

  11. A Reverse Monte Carlo study of H+D Lyman alpha absorption from QSO spectra

    CERN Document Server

    Levshakov, S A; Takahara, F

    1997-01-01

    A new method based on a Reverse Monte Carlo [RMC] technique and aimed at the inverse problem in the analysis of interstellar (intergalactic) absorption lines is presented. The line formation process in chaotic media with a finite correlation length $(l > 0)$ of the stochastic velocity field (mesoturbulence) is considered. This generalizes the standard assumption of completely uncorrelated bulk motions $(l \\equiv 0)$ in the microturbulent approximation which is used for the data analysis up-to-now. It is shown that the RMC method allows to estimate from an observed spectrum the proper physical parameters of the absorbing gas and simultaneously an appropriate structure of the velocity field parallel to the line-of-sight. The application to the analysis of the H+D Ly$\\alpha$ profile is demonstrated using Burles & Tytler [B&T] data for QSO 1009+2956 where the DI Ly$\\alpha$ line is seen at $z_a = 2.504$. The results obtained favor a low D/H ratio in this absorption system, although our upper limit for the ...

  12. The Lyman-alpha Forest Power Spectrum from the Sloan Digital Sky Survey

    CERN Document Server

    McDonald, P; Burles, S; Schlegel, D J; Weinberg, D H; Shih, D; Schaye, J; Schneider, D P; Brinkmann, J; Brunner, R J; Fukugita, M; Donald, Patrick Mc; Seljak, Uros; Burles, Scott; Schlegel, David J.; Weinberg, David H.; Shih, David; Schaye, Joop; Schneider, Donald P.; Brunner, Robert J.; Fukugita, Masataka

    2004-01-01

    We measure the power spectrum, P_F(k,z), of the transmitted flux in the Ly-alpha forest using 3035 high redshift quasar spectra from the Sloan Digital Sky Survey. This sample is almost two orders of magnitude larger than any previously available data set, yielding statistical errors of ~0.6% and ~0.005 on, respectively, the overall amplitude and logarithmic slope of P_F(k,z). This unprecedented statistical power requires a correspondingly careful analysis of the data and of possible systematic contaminations in it. For this purpose we reanalyze the raw spectra to make use of information not preserved by the standard pipeline. We investigate the details of the noise in the data, resolution of the spectrograph, sky subtraction, quasar continuum, and metal absorption. We find that background sources such as metals contribute significantly to the total power and have to be subtracted properly. We also find clear evidence for SiIII correlations with the Ly-alpha forest and suggest a simple model to account for thi...

  13. Lyman Alpha Emitters at Redshift 5.7 in the COSMOS Field

    CERN Document Server

    Murayama, T; Scoville, N Z; Ajiki, M; Sanders, D B; Mobasher, B; Aussel, H; Capak, P; Koekemoer, A; Shioya, Y; Nagao, T; Carilli, C; Ellis, Richard S; Garilli, B; Giavalisco, M; Kitzbichler, M G; LeFevre, O; MacCagni, D; Schinnerer, E; Smolcic, V; Tribiano, S; Cimatti, A; Komiyama, Yu; Miyazaki, S; Sasaki, S S; Koda, J; Karoji, H

    2007-01-01

    We present results from a narrow-band optical survey of a contiguous area of 1.95 deg^2, covered by the Cosmic Evolution Survey (COSMOS). Both optical narrow-band (lambda_c = 8150 AA and Delta_lambda = 120 AA) and broad-band (B, V, g', r', i', and z') imaging observations were performed with the Subaru prime-focus camera, Suprime-Cam on the Subaru Telescope. We provide the largest contiguous narrow-band survey, targetting Ly alpha emitters (LAEs) at z~5.7. We find a total of 119 LAE candidates at z~5.7. Over the wide-area covered by this survey, we find no strong evidence for large scale clustering of LAEs. We estimate a star formation rate (SFR) density of ~7*10^-4 M_sun yr^-1 Mpc^-3 for LAEs at z~5.7, and compare it with previous measurements.

  14. Lyman-alpha observations in the vicinity of Saturn with Copernicus

    Science.gov (United States)

    Barker, E.; Cazes, S.; Emerich, C.; Vidal-Madjar, A.; Owen, T.

    1980-01-01

    For the first time, high-resolution Ly-alpha observations of the Saturn vicinity were completed with the Princeton spectrometer on board the Copernicus satellite. They showed that near a minimum solar activity the emissions related to several sources are 250 + or - 50 rayleighs for the interplanetary medium in a near-downwind direction, less than 100 rayleighs for the rings, 200 + or - 100 rayleighs for a torus linked to the Titan orbit, and 1400 + or - 450 rayleighs for the disk of Saturn. These results induce some constraints through the corresponding theoretical evaluations: the B ring as the primary source of the atoms for the ring emissions; an efficient production mechanism for hydrogen atoms in the Titan torus; and a slightly larger eddy diffusion coefficient in the Saturn atmosphere than in the Jupiter atmosphere near solar minimum.

  15. Calibrating cosmological radiative transfer simulations with Lyman alpha forest data: Evidence for large spatial UV background fluctuations at z ~ 5.6 - 5.8 due to rare bright sources

    CERN Document Server

    Chardin, Jonathan; Aubert, Dominique; Puchwein, Ewald

    2015-01-01

    We calibrate here cosmological radiative transfer simulation with ATON/RAMSES with a range of measurements of the Lyman alpha opacity from QSO absorption spectra. We find the Lyman alpha opacity to be very sensitive to the exact timing of hydrogen reionisation. Models reproducing the measured evolution of the mean photoionisation rate and average mean free path reach overlap at z ~ 7 and predict an accelerated evolution of the Lyman alpha opacity at z > 6 consistent with the rapidly evolving luminosity function of Lyman alpha emitters in this redshift range. Similar to "optically thin" simulations our full radiative transfer simulations fail, however, to reproduce the high-opacity tail of the Lyman alpha opacity PDF at z > 5. We argue that this is due to spatial UV fluctuations in the post-overlap phase of reionisation on substantially larger scales than predicted by our source model, where the ionising emissivity is dominated by large numbers of sub-L* galaxies. We further argue that this suggests a signific...

  16. Magellan LDSS3 emission confirmation of galaxies hosting metal-rich Lyman-alpha absorption systems

    CERN Document Server

    Straka, Lorrie A; York, Donald G; Bowen, David V; Florian, Michael; Kulkarni, Varsha P; Lundgren, Britt; Peroux, Celine

    2015-01-01

    Using the Low Dispersion Survey Spectrograph 3 at the Magellan II Clay Telescope in Chile, we target candidate absorption host galaxies detected in deep optical imaging (reaching limiting apparent magnitudes of 23.0-26.5 in g; r; i; and z filters) in the fields of three QSOs, each of which shows the presence of high metallicity, strong NHI absorption systems in their spectra (Q0826-2230: zabs=0.9110, Q1323-0021: zabs = 0.7160, Q1436-0051: zabs = 0.7377; 0.9281). We confirm host galaxies at redshifts 0.7387, 0.7401, and 0.9286 for two out of four of the Ly-alpha absorption systems. For these systems, we are able to determine the SFRs; impact parameters (known from previous imaging detections); the velocity shift between the absorption and emission redshifts; and, for one system, also the emission metallicity. Based on previous photometry, we find these galaxies have L>L*. The SFRs for these galaxies, based on [O II] emission, are in the range 11-25 M_sol/yr (uncorrected for dust), while the impact parameters l...

  17. Damped Lyman Alpha Gas Metallicities at Redshifts z=0.9-2.0 from SDSS Spectra

    CERN Document Server

    Nestor, D B; Turnshek, D A; Vanden Berk, Daniel E; Nestor, Daniel B.; Rao, Sandhya M.; Turnshek, David A.; Berk, Daniel Vanden

    2003-01-01

    Using Sloan Digital Sky Survey (SDSS) early data release spectra, we have identified 370 MgII absorption systems with MgII 2796 rest equivalent widths >= 1A and redshifts z=0.9-2.2. From our previous and ongoing HST UV spectroscopic studies, we estimate that the mean neutral hydrogen column density of a system selected in this manner is N(HI) = 3.6 +/- 1.3 x10^(20) atoms cm^(-2), which corresponds to the damped Ly-alpha (DLA) regime. We have formed high signal-to-noise ratio composite spectra using 223 of these systems with z=0.9-2.0 in order to study the strength of the ZnII and CrII absorption lines corresponding to this mean neutral hydrogen column density. After making a correction for missed DLAs, overall we find that [Zn/H] = -1.13 +/- 0.19. We find [Cr/Zn] = -0.45 +/- 0.13, which indicates that approx 65% of the Cr is depleted on to grains, but this does not correct for the missed DLAs. We have also derived Zn and Cr abundances in two kinematic regimes, and within each regime we consider two redshift i...

  18. Galactic winds and stellar populations in Lyman $\\alpha$ emitting galaxies at z ~ 3.1

    CERN Document Server

    McLinden, Emily M; Malhotra, Sangeeta; Finkelstein, Steven L; Richardson, Mark L A; Smith, Brent; Tilvi, Vithal S

    2014-01-01

    We present a sample of 33 spectroscopically confirmed z ~ 3.1 Ly$\\alpha$-emitting galaxies (LAEs) in the Cosmological Evolution Survey (COSMOS) field. This paper details the narrow-band survey we conducted to detect the LAE sample, the optical spectroscopy we performed to confirm the nature of these LAEs, and a new near-infrared spectroscopic detection of the [O III] 5007 \\AA\\ line in one of these LAEs. This detection is in addition to two [O III] detections in two z ~ 3.1 LAEs we have reported on previously (McLinden et al 2011). The bulk of the paper then presents detailed constraints on the physical characteristics of the entire LAE sample from spectral energy distribution (SED) fitting. These characteristics include mass, age, star-formation history, dust content, and metallicity. We also detail an approach to account for nebular emission lines in the SED fitting process - wherein our models predict the strength of the [O III] line in an LAE spectrum. We are able to study the success of this prediction be...

  19. Evolution in the properties of Lyman-alpha emitters from redshifts z ~ 3 to z ~ 2

    CERN Document Server

    Nilsson, Kim K; Moeller, Palle; Freudling, Wolfram; Fynbo, Johan P U; Meisenheimer, Klaus; Laursen, Peter; Oestlin, Goeran

    2008-01-01

    Context: Narrow-band surveys for Ly-alpha emitters (LAEs) is a powerful tool in detecting high, and very high, redshift galaxies. Even though samples are growing at redshifts z = 3 - 6, the nature of these galaxies is still poorly known. Aims: To study the properties of z = 2.25 LAEs and compare those with the properties of z > 3 LAEs. Methods: We present narrow-band imaging made with the MPG/ESO 2.2m telescope with the WFI detector. We have made a selection for emission-line objects and find 170 candidate typical LAEs and 17 candidates which we regard as high UV-transmission LAEs. We have derived the magnitudes of these objects in 8 bands from u* to Ks, and studied if they have X-ray and/or radio counterparts. Results: We show that there has been significant evolution in the properties of LAEs between redshift z ~ 3 and z = 2.25. The spread in spectral energy distributions (SEDs) at the lower redshift is larger and we detect a significant AGN contribution in the sample. The distribution of the equivalent wid...

  20. Diffuse Interstellar Bands in Seven Intermediate Redshift Damped Lyman-Alpha Absorbers

    CERN Document Server

    Lawton, Brandon; York, Brian A; Ellison, Sara L; Snow, Theodore P; Johnson, Rachel A; Ryan, Sean G; Benn, Chris R

    2008-01-01

    We present equivalent width measurements and limits of six diffuse interstellar bands (DIBs) in seven damped Ly-alpha absorbers (DLAs) over the redshift range 0.091

  1. Impact of Cosmic Variance on the Galaxy-Halo Connection for Lyman-$\\alpha$ Emitters

    CERN Document Server

    Mejia-Restrepo, Julian E

    2016-01-01

    In this paper we study the impact of cosmic variance and observational uncertainties in constraining the mass and occupation fraction, $f_{\\rm occ}$, of dark matter halos hosting Ly-$\\alpha$ Emitting Galaxies (LAEs) at high redshift. To this end, we construct mock catalogs from an N-body simulation to match the typical size of observed fields at $z=3.1$ ($\\sim 1 {\\rm deg^2}$). In our model a dark matter halo with mass in the range $M_{\\rm min}

  2. Observational estimates of the initial power spectrum at small scale from Lyman-$\\alpha$ absorbers

    CERN Document Server

    Demianski, M

    2003-01-01

    We present a new method of measuring the power spectrum of initial perturbations to an unprecedently small scale of $\\sim$ 10$h^{-1}$ kpc. We apply this method to a sample of 4500 Ly-$\\alpha$ absorbers and recover the cold dark matter (CDM) like power spectrum at scales $\\geq 300h^{-1}$kpc with a precision of $\\sim$ 10%. However at scales $\\sim 10 - 300 h^{-1}$kpc the measured and CDM--like spectra are noticeable different. This result suggests a complex inflation with generation of excess power at small scales. The magnitude and reliability of these deviations depend also upon the possible incompleteness of our sample and poorly understood process of formation of weak absorbers. Confirmation of the CDM--like shape of the initial power spectrum or detection of its distortions at small scales are equally important for widely discussed problems of physics of the early Universe, galaxy formation, and reheating of the Universe. Our method links the observed mass function of absorbers with the correlation function...

  3. Lyman-{\\alpha} Forest and Cosmic Weak Lensing in a Warm Dark Matter Universe

    CERN Document Server

    Markovič, Katarina

    2013-01-01

    We review the current state of the theory of large scale structure in a warm dark matter (WDM) cosmological model. In particular, we focus on the non-linear modelling of the matter power spectrum and on the mass function of dark matter haloes. We describe the results of N-body simulations with WDM and mention the effects that could be induced by baryonic physics. We also examine the halo model of large scale structure and its recently suggested modifications for a WDM cosmology, which account for the small scale smoothness of the initial matter density field and better fit the results of N-body simulations. Having described the theoretical models, we discuss the current lower limits on the WDM particle mass, m_w, which correspond to upper limits on the WDM temperature under the assumption that the particles are thermal relics. The best such constraints come from the Ly{\\alpha} forest and exclude all masses below 3.3 keV at the 2{\\sigma} confidence level. We finally review the forecasts for future lensing surv...

  4. Cosmological parameters from combining the Lyman-alpha forest with CMB, galaxy clustering and SN constraints

    CERN Document Server

    Seljak, U; McDonald, P; Seljak, Uros; Slosar, Anze; Donald, Patrick Mc

    2006-01-01

    We combine the Ly-alpha forest power spectrum (LYA) from the Sloan Digital Sky Survey (SDSS) and high resolution spectra with the cosmic microwave background (CMB) including 3-year WMAP, supernovae (SN) and galaxy clustering constraints to derive new constraints on cosmological parameters. The existing LYA power spectrum analysis is supplemented by constraints on the mean flux decrement derived using a principal component analysis for quasar continua, which improves the LYA constraints on the linear power. The joint analysis reduces the errors on all parameters and prefers the simplest 6 parameter cosmological model. We find some tension between the WMAP3 and LYA power spectrum amplitudes, at the ~2 sigma level, which is partially alleviated by the inclusion of other observations: we find sigma_8=0.85+-0.02 compared to sigma_8=0.80+-0.03 without LYA. For the slope we find n_s=0.965+-0.012. We find no evidence for running of the spectral index, dn/dln k=-0.020+-0.012, in agreement with inflation. The limits on...

  5. Keck Spectroscopy of Lyman-break Galaxies and its Implications for the UV-continuum and Ly_alpha Luminosity Functions at z>6

    CERN Document Server

    Jiang, Linhua; Kashikawa, Nobunari; Walth, Gregory; Matsuda, Yuichi; Shimasaku, Kazuhiro; Nagao, Tohru; Ota, Kazuaki; Ouchi, Masami

    2011-01-01

    We present Keck spectroscopic observations of z>6 Lyman-break galaxy (LBG) candidates in the Subaru Deep Field (SDF). The candidates were selected as i'-dropout objects down to z'=27 AB magnitudes from an ultra-deep SDF z'-band image. With the Keck spectroscopy we identified 19 LBGs with prominent Ly_alpha emission lines at 6100 A. This well-defined spectroscopic sample spans a UV-continuum luminosity range of -21.8~6.2 after we correct for sample incompleteness. We find that our measurement of the UV LF is consistent with the results of previous studies based on photometric LBG samples at 56.

  6. LRO Lyman Alpha Mapping Project (LAMP) Far-UV Maps: A New View of the Moon

    Science.gov (United States)

    Retherford, K. D.; Greathouse, T. K.; Gladstone, G. R.; Hendrix, A. R.; Mandt, K. E.; Egan, A. F.; Kaufmann, D. E.; Hayne, P. O.; Stern, S. A.; Parker, J. Wm.; Davis, M. W.; Grava, C.; Hurley, D. M.; Cahill, J. T. S.; Stickle, A. M.; Liu, Y.; Bullock, M. A.; Pryor, W. R.; Feldman, P. D.; Mukherjee, J.; Mokashi, P.; Seifert, C. J.; Versteeg, M. H.

    2016-05-01

    The LRO-LAMP investigation has provided a unique view at far-UV wavelengths, and uses an innovative way to measure surface reflectance within permanently shaded regions in order to constrain the water frost abundance at the surface.

  7. Optical to mid-IR observations of Lyman-alpha galaxies at redshift 5 in the HUDF: a young and low mass population

    CERN Document Server

    Pirzkal, N; Rhoads, J E; Xu, C; Pirzkal, Norbert; Malhotra, Sangeeta; Rhoads, James E.; Xu, Chun

    2006-01-01

    High redshift galaxies selected on the basis of their strong Lyman-alpha emission tend to be young in age and small in mass and size. We show this by analyzing spectral Energy distribution of nine Lyman-alpha emitting (LAE) galaxies at redshifts from 4.1 to 5.7 in the Hubble Ultra Deep Field (HUDF). Restframe UV to optical (700 to 7500 Angstrom) luminosities (or upper limits) are used to constrain old stellar populations. We derive best fit, as well as maximally massive and maximally old, properties of all nine objects. We show that these objects are all very young, being most likely only a few millions years old, and not massive, the mass in stars being 1e6 to 1e8 solar masses. Deep Spitzer Infrared Array Camera (IRAC) observations of these objects, even in cases where objects were not detected, were crucial in constraining the masses of these objects. The space density of these objects, about 1.25e-4 per comoving cubic Mpc, is comparable to previously reported space density of LAEs at moderate to high redsh...

  8. Mechanism and computational model for Lyman-{alpha}-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas

    Energy Technology Data Exchange (ETDEWEB)

    Louchev, Oleg A.; Saito, Norihito; Wada, Satoshi [Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Bakule, Pavel [STFC, ISIS Facility, Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX (United Kingdom); Yokoyama, Koji [Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Advanced Meson Science Laboratory, RIKEN Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan); Ishida, Katsuhiko; Iwasaki, Masahiko [Advanced Meson Science Laboratory, RIKEN Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan)

    2011-09-15

    We present a theoretical model combined with a computational study of a laser four-wave mixing process under optical discharge in which the non-steady-state four-wave amplitude equations are integrated with the kinetic equations of initial optical discharge and electron avalanche ionization in Kr-Ar gas. The model is validated by earlier experimental data showing strong inhibition of the generation of pulsed, tunable Lyman-{alpha} (Ly-{alpha}) radiation when using sum-difference frequency mixing of 212.6 nm and tunable infrared radiation (820-850 nm). The rigorous computational approach to the problem reveals the possibility and mechanism of strong auto-oscillations in sum-difference resonant Ly-{alpha} generation due to the combined effect of (i) 212.6-nm (2+1)-photon ionization producing initial electrons, followed by (ii) the electron avalanche dominated by 843-nm radiation, and (iii) the final breakdown of the phase matching condition. The model shows that the final efficiency of Ly-{alpha} radiation generation can achieve a value of {approx}5x10{sup -4} which is restricted by the total combined absorption of the fundamental and generated radiation.

  9. The First Observations of Low-Redshift Damped Lyman-{\\alpha} Systems with the Cosmic Origins Spectrograph: Chemical Abundances and Affiliated Galaxies

    CERN Document Server

    Battisti, A J; Tripp, T M; Prochaska, J X; Werk, J K; Jenkins, E B; Lehner, N; Tumlinson, J; Thom, C

    2011-01-01

    We present Cosmic Origins Spectrograph (COS) measurements of metal abundances in eight 0.083 < zabs < 0.321 damped Lyman-{\\alpha} (DLA) and sub-damped Ly{\\alpha} absorption systems serendipitously discovered in the COS-Halos survey. We find that these systems show a large range in metallicities, with -1.10 < [Z/H] < 0.31, similar to the spread found at higher redshifts. These low-redshift systems on average have subsolar metallicities, but do show a rise in metallicity over cosmic time when compared to higher-redshift systems. Utilizing our sources and those in the literature, we find the average sub-DLA metallicity is higher than the average DLA metallicity at all redshifts. Nitrogen is underabundant with respect to {\\alpha}-group elements in all but perhaps one of the absorbers. In some cases, [N/{\\alpha}] is significantly below the lowest nitrogen measurements in nearby galaxies; the nitrogen abundances are more similar to those observed in high-redshift DLAs. Systems for which depletion patter...

  10. Large scale opacity fluctuations in the Lyman alpha forest: evidence for QSOs dominating the ionising UV background at z ~ 5.5-6 ?

    CERN Document Server

    Chardin, Jonathan; Haehnelt, Martin G

    2016-01-01

    Lyman-alpha forest data probing the post-reionization Universe shows surprisingly large opacity fluctuations over rather large ($\\ge$50 comoving Mpc/h) spatial scales. We model these fluctuations using a hybrid approach utilizing the large volume Millennium simulation to predict the spatial distribution of QSOs combined with smaller scale full hydrodynamical simulation performed with RAMSES and post-processed with the radiative transfer code ATON. We produce realictic mock absorption spectra that account for the contribution of galaxies and QSOs to the ionising UV background. This improved models confirm our earlier findings that a significant ($\\ge$50%) contribution of ionising photons from QSOs can explain the large reported opacity fluctuations on large scales. The inferred QSO luminosity function is thereby consistent with recent estimates of the space density of QSOs at this redshift. Our simulations still somewhat struggle, however, to reproduce the very long (110 comoving Mpc/h) high opacity absorption...

  11. The Lyman-alpha luminosity function at z=5.7-6.6 and the steep drop of the faint end: implications for reionization

    CERN Document Server

    Santos, Sérgio; Matthee, Jorryt

    2016-01-01

    We present new results from the widest narrow band survey search for Lyman-alpha (Lya) emitters at z=5.7, just after reionization. We survey a total of 7 deg$^2$ spread over the COSMOS, UDS and SA22 fields. We find over 11,000 line emitters, out of which 514 are robust Lya candidates at z=5.7 within a volume of 6.3x10$^6$ Mpc$^3$. Our Lya emitters span a wide range in Lya luminosities, from faint to bright (L$_{\\rm Ly\\alpha}\\sim10^{42.5-44}$ erg s$^{-1}$) and rest-frame equivalent widths (EW$_0$~25-1000 \\AA) in a single, homogeneous data-set. By combining all our fields we find that the faint end slope of the z=5.7 Lya luminosity function is very steep, with $\\alpha=-2.3^{+0.4}_{-0.3}$. We also present an updated z=6.6 Lya luminosity function, based on comparable volumes and obtained with the same methods, which we directly compare with that at z=5.7. We find a significant decline of the number density of faint Lya emitters from z=5.7 to z=6.6 (by $0.5\\pm0.1$ dex), but no evolution at the bright end/no evolut...

  12. Project Lyman

    CERN Document Server

    McCandliss, Stephan R; Blair, William P; Kaiser, Mary Elizabeth; Feldman, Paul D; Meurer, Gerhardt R; Dixon, William V; Sahnow, David J; Neufeld, David A; Lupu, Roxana E; Fleming, Brian; Smee, Stephen A; Andersson, B G; Moseley, Samuel H; Kutyrev, Alexander S; Li, Mary J; Sonneborn, George; Siegmund, Oswald H W; Vallerga, John V; Welsh, Barry Y; Stiavelli, Massimo; Windhorst, Rogier A; Shapley, Alice E

    2008-01-01

    We explore the design of a space mission, Project Lyman, which has the goal of quantifying the ionization history of the universe from the present epoch to a redshift of z ~ 3. Observations from WMAP and SDSS show that before a redshift of z >~ 6 the first collapsed objects, possibly dwarf galaxies, emitted Lyman continuum (LyC) radiation shortward of 912 A, reionizing most of the universe. How LyC escapes from galactic environments, whether it induces positive or negative feedback on the local and global collapse of structures, and the role played by clumping, molecules, metallicity and dust are major unanswered theoretical questions, requiring observational constraint. Numerous intervening Lyman limit systems, which frustrate the detection of LyC from high z objects, thin below z ~ 3 where there are a few objects with apparently very high fesc. At low z there are only controversial detections and a handful of upper limits. A wide-field multi-object spectroscopic survey with moderate spectral and spatial res...

  13. The Gravitational Lensing in the QSO 1208+10 from the Proximity Effect in its $Lyman \\alpha$ Forest

    CERN Document Server

    Giallongo, E; Cristiani, S; D'Odorico, S

    1999-01-01

    The quasar Q1208+1011 (z_{em}=3.8) is the second highest redshift double quasar ever detected. Several indications point toward it being a gravitational lensed system, although a definitive proof is still lacking. We present new evidence of its lensed nature based on the weakness of the ``proximity effect'' measured in the high resolution Lyman absorption spectrum of the QSO. A luminosity amplification as large as 22 has been derived from this analysis. Indications on the redshift of the lensing galaxy can be obtained from the analysis of the intervening heavy element absorption systems discovered in the QSO high resolution spectrum. On statistical and dynamical grounds a MgII system present at z=1.13 appears as the most likely candidate for the lensing galaxy. We compare the observed parameters with a simple isothermal model for the lens to derive the properties of the lensing galaxy. The resulting magnification factor is smaller, although marginally consistent with that derived by the analysis of the proxim...

  14. Molecular Hydrogen in the Damped Lyman-alpha System towards GRB 120815A at z=2.36

    CERN Document Server

    Krühler, T; Fynbo, J P U; Vreeswijk, P M; Schmidl, S; Malesani, D; Christensen, L; De Cia, A; Hjorth, J; Jakobsson, P; Kann, D A; Kaper, L; Vergani, S D; Afonso, P M J; Covino, S; Postigo, A de Ugarte; D'Elia, V; Filgas, R; Goldoni, P; Greiner, J; Hartoog, O E; Milvang-Jensen, B; Nardini, M; Piranomonte, S; Rossi, A; Sánchez-Ramírez, R; Schady, P; Schulze, S; Sudilovsky, V; Tanvir, N R; Tagliaferri, G; Watson, D J; Wiersema, K; Wijers, R A M J; Xu, D

    2013-01-01

    [Abridged] Molecular hydrogen H_2 is a key requirement for star-formation, frequently observed along sightlines in the Galaxy and to the Magellanic Clouds, but notoriously hard to detect directly beyond z ~ 0. In the DLAs associated with long gamma-ray bursts (GRBs), which are tightly linked to vigorous star-formation, H_2 has remained largely elusive, and has been unequivocally detected only towards GRB 080607 and possibly towards GRB 060206. Here, we present the discovery of H_2-rich gas, including the presence of vibrationally-excited H_2^* in the optical spectrum of the afterglow of GRB 120815A at z=2.36 obtained with X-shooter at the VLT. The galactic environment of GRB 120815A is characterized by a strong DLA with log(N(H)/cm^-2) = 21.95 +/- 0.10, prominent H_2 absorption in the Lyman-Werner bands (log(N(H_2)/cm^-2) = 20.53 +/- 0.04) and thus a molecular gas fraction log f(H_2)=-1.14 +/- 0.10. The distance d between the absorbing neutral gas and GRB 120815A is constrained via photo-excitation modeling o...

  15. PACS-Herschel FIR detections of Lyman-alpha emitters at 2.0

    CERN Document Server

    Oteo, I; García, A M Pérez; Cepa, J; Ederoclite, A; Sánchez-Portal, M; Pintos-Castro, I; Pérez-Martínez, R; Altieri, B; Andreani, P; Aussel, H; Berta, S; Cimatti, A; Daddi, E; Elbaz, D; Schreiber, N Förster; Genzel, R; Lutz, D; Magnelli, B; Maiolino, R; Poglitsch, A; Popesso, P; Pozzi, F; Sturm, E; Tacconi, L; Valtchanov, I

    2012-01-01

    In this work we analyze the physical properties of a sample of 56 spectroscopically selected star-forming (SF) Ly$\\alpha$ emitting galaxies at 2.0$\\lesssim$z$\\lesssim$3.5 using both a spectral energy distribution (SED) fitting procedure from rest-frame UV to mid-IR and direct 160$\\mu$m observations taken with the Photodetector Array Camera & Spectrometer (PACS) instrument onboard \\emph{Herschel Space Observatory}. We define LAEs as those Ly$\\alpha$ emitting galaxies whose rest-frame Ly$\\alpha$ equivalent widths (Ly$\\alpha$ EW$_{rest-frame}$) are above 20\\AA, the typical threshold in narrow-band searches. Ly$\\alpha$ emitting galaxies with Ly$\\alpha$ EW$_{rest-frame}$ are called non-LAEs. As a result of an individual SED fitting for each object, we find that the studied sample of LAEs contains galaxies with ages mostly below 100Myr and a wide variety of dust attenuations, SFRs, and stellar masses. The heterogeneity in the physical properties is also seen in the morphology, ranging from bulge-like galaxies t...

  16. The ESO UVES Advanced Data Products Quasar Sample - VI. Sub-Damped Lyman-$\\alpha$ Metallicity Measurements and the Circum-Galactic Medium

    CERN Document Server

    Quiret, S; Zafar, T; Kulkarni, V P; Jenkins, E D; Milliard, B; Rahmani, H; Popping, A; Sandhya, R M; Turnshek, D A; Monier, E M

    2016-01-01

    The Circum-Galactic Medium (CGM) can be probed through the analysis of absorbing systems in the line-of-sight to bright background quasars. We present measurements of the metallicity of a new sample of 15 sub-damped Lyman-$\\alpha$ absorbers (sub-DLAs, defined as absorbers with 19.0 < log N(H I) < 20.3) with redshift 0.584 < $\\rm z_{abs}$ < 3.104 from the ESO Ultra-Violet Echelle Spectrograph (UVES) Advanced Data Products Quasar Sample (EUADP). We combine these results with other measurements from the literature to produce a compilation of metallicity measurements for 92 sub-DLAs as well as a sample of 362 DLAs. We apply a multi-element analysis to quantify the amount of dust in these two classes of systems. We find that either the element depletion patterns in these systems differ from the Galactic depletion patterns or they have a different nucleosynthetic history than our own Galaxy. We propose a new method to derive the velocity width of absorption profiles, using the modeled Voigt profile feat...

  17. Hubble Space Telescope Observations of Sub-Damped Lyman-alpha Absorbers at z < 0.5, and Implications for Galaxy Chemical Evolution

    CERN Document Server

    Som, Debopam; Meiring, Joseph; York, Donald G; Péroux, Celine; Lauroesch, James T; Aller, Monique C; Khare, Pushpa

    2015-01-01

    We report observations of four sub-damped Lyman-alpha (sub-DLA) quasar absorbers at z<0.5 obtained with the Hubble Space Telescope Cosmic Origins Spectrograph. We measure the available neutrals or ions of C, N, O, Si, P, S, Ar, Mn, Fe, and/or Ni. Our data have doubled the sub-DLA metallicity samples at z<0.5 and improved constraints on sub-DLA chemical evolution. All four of our sub-DLAs are consistent with near-solar or super-solar metallicities and relatively modest ionization corrections; observations of more lines and detailed modeling will help to verify this. Combining our data with measurements from the literature, we confirm previous suggestions that the N(HI)-weighted mean metallicity of sub-DLAs exceeds that of DLAs at all redshifts studied, even after making ionization corrections for sub-DLAs. The absorber toward PHL 1598 shows significant dust depletion. The absorbers toward PHL 1226 and PKS 0439-433 show the S/P ratio consistent with solar, i.e., they lack a profound odd-even effect. The a...

  18. Dust-depletion sequences in damped Lyman-{\\alpha} absorbers: a unified picture from low-metallicity systems to the Galaxy

    CERN Document Server

    De Cia, Annalisa; Mattsson, Lars; Petitjean, Patrick; Srianand, Raghunathan; Gavignaud, Isabelle; Jenkins, Edward B

    2016-01-01

    We study metal depletion due to dust in the interstellar medium (ISM) to infer the properties of dust grains and characterize the metal and dust content of galaxies, down to low metallicity and intermediate redshift z. We provide metal column densities and abundances of a sample of 70 damped Lyman-{\\alpha} absorbers (DLAs) towards quasars, observed at high spectral resolution with the Very Large Telescope (VLT) Ultraviolet and Visual Echelle Spectrograph (UVES). This is the largest sample of phosphorus abundances measured in DLAs so far. We use literature measurements for Galactic clouds to cover the high-metallicity end. We discover tight (scatter <= 0.2 dex) correlations between [Zn/Fe] and the observed relative abundances, which are due to dust depletion. This implies that grain-growth in the ISM is an important process of dust production. These sequences are continuous in [Zn/Fe] from dust-free to dusty DLAs, and to Galactic clouds, suggesting that the availability of refractory metals in the ISM is cr...

  19. Metallicities, dust and molecular content of a QSO-Damped Lyman-{\\alpha} system reaching log N (H i) = 22: An analog to GRB-DLAs

    CERN Document Server

    Guimarães, R; Petitjean, P; Ledoux, C; Srianand, R; Lopez, S; Rahmani, H

    2012-01-01

    We present the elemental abundance and H2 content measurements of a Damped Lyman-{\\alpha} (DLA) system with an extremely large H i column density, log N(H i) (cm-2) = 22.0+/-0.10, at zabs = 3.287 towards the QSO SDSS J 081634+144612. We measure column densities of H2, C i, C i^*, Zn ii, Fe ii, Cr ii, Ni ii and Si ii from a high signal-to-noise and high spectral resolution VLT-UVES spectrum. The overall metallicity of the system is [Zn/H] = -1.10 +/- 0.10 relative to solar. Two molecular hydrogen absorption components are seen at z = 3.28667 and 3.28742 (a velocity separation of \\approx 52 km s-1) in rotational levels up to J = 3. We derive a total H2 column density of log N(H2) (cm-2) = 18.66 and a mean molecular fraction of f = 2N(H2)/[2N(H2) + N(H i)] = 10-3.04+/-0.37, typical of known H2-bearing DLA systems. From the observed abundance ratios we conclude that dust is present in the Interstellar Medium (ISM) of this galaxy, with a enhanced abundance in the H2-bearing clouds. However, the total amount of dus...

  20. Low-Redshift Damped Lyman Alpha Galaxies Towards the Quasars B2 0827+243, PKS 0952+179, PKS 1127-145, and PKS 1629+120

    CERN Document Server

    Rao, S M; Turnshek, D A; Lane, W M; Monier, E M; Bergeron, J; Rao, Sandhya M.; Nestor, Daniel B.; Turnshek, David A.; Lane, Wendy M.; Monier, Eric M.; Bergeron, Jacqueline

    2003-01-01

    We present optical and near-infrared ground-based imaging results on four low-redshift damped Lyman alpha (DLA) galaxies. The corresponding DLA systems were discovered in our Hubble Space Telescope spectroscopic surveys for DLAs in known strong MgII absorption-line systems towards the quasars B2 0827+243 (z{DLA}=0.525), PKS 0952+179 (z{DLA}=0.239), PKS 1127-145 (z_{DLA}=0.313), and PKS 1629+120 (z{DLA}=0.532). The DLA galaxies span a mixture of morphological types from patchy, irregular, and low-surface-brightness to spiral galaxies. The luminosities range from 0.02L_K^* to 1.2L_K^*. We also discovered several extremely red objects (EROs) in two of these fields and discuss the possibility that they are associated with the DLA galaxies. These observations add to the small but growing list of DLA galaxies at low redshift. At the present time, 14 DLA galaxies in the redshift range $0.05 \\lesssim z \\lesssim 1$ have been studied. The distributions of DLA galaxy properties for these 14 cases are discussed and some ...

  1. The Development of Replicated Optical Integral Field Spectrographs and their Application to the Study of Lyman-alpha Emission at Moderate Redshifts

    Science.gov (United States)

    Chonis, Taylor Steven

    In the upcoming era of extremely large ground-based astronomical telescopes, the design of wide-field spectroscopic survey instrumentation has become increasingly complex due to the linear growth of instrument pupil size with telescope diameter for a constant spectral resolving power. The upcoming Visible Integral field Replicable Unit Spectrograph (VIRUS), a baseline array of 150 copies of a simple integral field spectrograph that will be fed by 3:36 x 104 optical fibers on the upgraded Hobby-Eberly Telescope (HET) at McDonald Observatory, represents one of the first uses of large-scale replication to break the relationship between instrument pupil size and telescope diameter. By dividing the telescope's field of view between a large number of smaller and more manageable instruments, the total information grasp of a traditional monolithic survey spectrograph can be achieved at a fraction of the cost and engineering complexity. To highlight the power of this method, VIRUS will execute the HET Dark Energy Experiment (HETDEX) and survey & 420 degrees2 of sky to an emission line flux limit of ˜ 10-17 erg s-1 cm -2 to detect ˜ 106 Lyman-alpha emitting galaxies (LAEs) as probes of large-scale structure at redshifts of 1:9 ProQuest.).

  2. The First Systematic Survey for Lyman Alpha Emitters at z=7.3 with Red-sensitive Subaru/Suprime-Cam

    CERN Document Server

    Shibuya, Takatoshi; Ota, Kazuaki; Iye, Masanori; Ouchi, Masami; Furusawa, Hisanori; Shimasaku, Kazuhiro; Hattori, Takashi

    2011-01-01

    We have performed deep imaging surveys for Lyman Alpha emitters (LAEs) at redshift ~ 7.3 in two blank fields, the Subaru Deep Field (SDF) and the Subaru/XMM-Newton Deep Field (SXDF), using the Subaru/Suprime-Cam equipped with new red-sensitive CCDs and a new narrow-band filter, NB1006 (lambda_c=10,052A, FWHM=214A). By comparing the NB1006 magnitudes of detected objects with those at other shorter wavelength bands, we identified four objects as LAE candidates that exhibit luminosity excess in NB1006. By carrying out deep follow-up spectroscopy for three of them using Subaru/FOCAS and Keck/DEIMOS, a definitively asymmetric emission line is detected for one of them, SXDF-NB1006-2. Assuming this line is LyA, this object is a LAE at z=7.215 which has luminosity of 1.2^{+1.5}_{-0.6} x 10^{43} erg s-1, star formation rate (SFR) of 11 Mo yr-1 estimated from the LyA emission line, and a weighted skewness S_w = 4.90+-0.86. Another object, SDF-NB1006-2, shows variable photometry and is thus probably a quasar (QSO) or an...

  3. Photolytic behaviour of methane @ lyman alpha and 248 nm : studies in the frame of a simulation program of Titan's atmosphere (S.E.T. U.P.)

    Science.gov (United States)

    Gazeau, M. C.; Romanzin, C.; Benilan, Y.; Jolly, A.

    An experimental simulation program called S E T U P Theoretical and Experimental Simulations Useful for Planetology is currently developped in our laboratory One of our aim is to investigate the mechanisms implied in the atmospheric chemistry of Titan in order to improve their description in theoretical models Experimental simulations are planned using a dedicated device The latter consists of a reactor where the initial gas mixture will be submitted for the first time to both major energy sources that are responsible for the chemical evolution of Titan s atmosphere electrons and photons Cold plasma and a UV irradiation will be used to dissociate N 2 and CH 4 respectively Time resolved analysis of the resulting gas sample will be done using spectroscopic methods In Titan s atmosphere photolysis of methane mainly involves Lyman- alpha photons 121 6 nm Such mechanism can not be easily reproduced in the laboratory for several reasons - difficulty to work in the VUV range traditional photochemical lamps unsuitable for high speed kinetic studies ldots Therefore in our simulation experiments a pulsed laser KrF excimer delivering photons at 248 nm is used to dissociate methane Indeed a two photons 248 nm process is energetically equivalent to the single photon 121 6 nm one Hovewer branching ratios for the CH 3 CH 2 and CH radicals production and consequently the following photochemistry could be different Thus as a first step of this photochemical experiment photolysis of methane at 121 6 and 248 nm

  4. VLT/XSHOOTER & Subaru/MOIRCS Spectroscopy of HUDF-YD3: No Evidence for Lyman-alpha Emission at z=8.55

    CERN Document Server

    Bunker, Andrew J; Wilkins, Stephen M; Stanway, Elizabeth R; Lorenzoni, Silvio; Lacy, Mark; Jarvis, Matt J; Hickey, Samantha

    2013-01-01

    We present spectroscopic observations with VLT/XSHOOTER and Subaru/MOIRCS of a relatively bright Y-band drop-out galaxy in the Hubble Ultra Deep Field, first selected by Bunker et al. (2010), McLure et al. (2010) and Bouwens et al. (2010) to be a likely z~8-9 galaxy on the basis of its colours in the HST ACS and WFC3 images. This galaxy, HUDF.YD3 (also known as UDFy-38135539) has been targetted for VLT/SINFONI integral field spectroscopy by Lehnert et al. (2010), who published a candidate Lyman-alpha emission line at z=8.55 from this source. In our independent spectroscopy using two different infrared spectrographs (5 hours with VLT/XSHOOTER and 11 hours with Subaru/MOIRCS) we are unable to reproduce this line. We do not detect any emission line at the spectral and spatial location reported in Lehnert et al. (2010), despite the expected signal in our combined MOIRCS & XSHOOTER data being 5-sigma. The line emission also seems to be ruled out by the faintness of this object in recently extremely deep F105W ...

  5. A quasar reddened by a sub-parsec sized, metal-rich and dusty cloud in a damped Lyman-alpha absorber at z=2.13

    CERN Document Server

    Krogager, J -K; Noterdaeme, P; Zafar, T; Møller, P; Ledoux, C; Krühler, T; Stockton, A

    2015-01-01

    We present a detailed analysis of a red quasar at z=2.32 with an intervening damped Lyman-alpha absorber (DLA) at z=2.13. Using high quality data from the X-shooter spectrograph at ESO Very Large Telescope we find that the absorber has a metallicity consistent with Solar. We observe strong C I and H$_2$ absorption indicating a cold, dense absorbing medium. Partial coverage effects are observed in the C I lines, from which we infer a covering fraction of $27 \\pm 6$ % and a physical diameter of the cloud of 0.1 pc. From the covering fraction and size, we estimate the size of the background quasar's broad line region. We search for emission from the DLA counterpart in optical and near-infrared imaging. No emission is observed in the optical data. However, we see tentative evidence for a counterpart in the H and K' band images. The DLA shows high depletion (as probed by [Fe/Zn]=-1.22) indicating that significant amounts of dust must be present in the DLA. By fitting the spectrum with various dust reddened quasar ...

  6. Keck and VLT Observations of Super-damped Lyman-alpha Absorbers at z=2=2.5: Constraints on Chemical Compositions and Physical Conditions

    CERN Document Server

    Kulkarni, Varsha P; Morrison, Sean; Peroux, Celine; Quiret, Samuel; York, Donald G

    2015-01-01

    We report Keck/ESI and VLT/UVES observations of three super-damped Lyman-alpha quasar absorbers with H I column densities log N(HI) >= 21.7 at redshifts z=2-2.5. All three absorbers show similar metallicities (-1.3 to -1.5 dex), and dust depletion of Fe, Ni, and Mn. Two of the absorbers show supersolar [S/Zn] and [Si/Zn]. We combine our results with those for other DLAs to examine trends between N(HI), metallicity, dust depletion. A larger fraction of the super-DLAs lie close to or above the line [X/H]=20.59-log N(HI) in the metallicity vs. N(HI) plot, compared to the less gas-rich DLAs, suggesting that super-DLAs are more likely to be rich in molecules. Unfortunately, our data for Q0230-0334 and Q0743+1421 do not cover H2 absorption lines. For Q1418+0718, some H2 lines are covered, but not detected. CO is not detected in any of our absorbers. For DLAs with log N(HI) 21.7 may have somewhat narrower velocity dispersions delta v_90 than the less gas-rich DLAs, and may arise in cooler and/or less turbulent gas.

  7. Kiloparsec Mass/Light Offsets in the Galaxy Pair-Lyman-alpha Emitter Lens System SDSS\\,J1011$+$0143

    CERN Document Server

    Shu, Yiping; Moustakas, Leonidas A; Stern, Daniel; Dey, Arjun; Brownstein, Joel R; Burles, Scott; Spinrad, Hyron

    2016-01-01

    We report the discovery of significant mass/light offsets in the strong gravitational lensing system SDSS\\,J1011$+$0143. We use the high-resolution \\textsl{Hubble Space Telescope} (\\textsl{HST}) F555W- and F814W-band imaging and SDSS spectroscopy of this system, which consists of a close galaxy pair with a projected separation of $\\approx 4.2$ kpc at $z_{\\rm lens} \\sim 0.331$ lensing a Lyman-alpha emitter (LAE) at $z_{\\rm source} = 2.701$. Comparisons between the mass peaks inferred from lens models and light peaks from \\textsl{HST} imaging data reveal significant spatial mass/light offsets as large as $(1.72 \\pm 0.24 \\pm 0.34)$ kpc in both filter bands. Such large mass/light offsets, not seen in isolated field lens galaxies and relaxed galaxy groups, may be related to the interactions between the two lens galaxies. The detected mass/light offsets can potentially serve as an important test for the self-interacting dark matter model. However, other mechanisms such as dynamical friction on spatially differently...

  8. The chemistry of the most metal-rich damped Lyman $\\alpha$ systems at z$\\sim2$ II. Context with the Local Group

    CERN Document Server

    Berg, Trystyn A M; Prochaska, J Xavier; Venn, Kim A; Dessauges-Zavadsky, Miroslava

    2015-01-01

    Using our sample of the most metal-rich damped Lyman $\\alpha$ systems (DLAs) at z$\\sim2$, and two literature compilations of chemical abundances in 341 DLAs and 2818 stars, we present an analysis of the chemical composition of DLAs in the context of the Local Group. The metal-rich sample of DLAs at z$\\sim2$ probes metallicities as high as the Galactic disc and the most metal-rich dwarf spheroidals (dSphs), permitting an analysis of many elements typically observed in DLAs (Fe, Zn, Cr, Mn, Si, and S) in comparison to stellar abundances observed in the Galaxy and its satellites (in particular dSphs). Our main conclusions are: (1) non-solar [Zn/Fe] abundances in metal-poor Galactic stars and in dSphs over the full metallicity range probed by DLAs, suggest that Zn is not a simple proxy for Fe in DLAs and therefore not a suitable indicator of dust depletion. After correcting for dust depletion, the majority of DLAs have subsolar [Zn/Fe] similar to dSphs; (2) at [Fe/H]$\\sim-0.5$, a constant [Mn/Fe]$\\sim-0.5$ and ne...

  9. No evidence for Population III stars or a Direct Collapse Black Hole in the z = 6.6 Lyman-$\\alpha$ emitter 'CR7'

    CERN Document Server

    Bowler, R A A; Dunlop, J S; McLeod, D J; Stanway, E R; Eldridge, J J; Jarvis, M J

    2016-01-01

    The z = 6.6 Lyman-$\\alpha$ emitter 'CR7' has been claimed to have a Population III-like stellar population, or alternatively, be a candidate Direct Collapse Black Hole (DCBH). In this paper we investigate the evidence for these exotic scenarios using recently available, deeper, optical, near-infrared and mid-infrared imaging. We find strong Spitzer/IRAC detections for the main component of CR7 at 3.6 and 4.5 microns, and show that it has a blue colour ([3.6] - [4.5] $= -1.2\\pm 0.3$). This colour cannot be reproduced by current Pop. III or pristine DCBH models. Instead, the results suggest that the [3.6] band is contaminated by the [OIII]4959,5007 emission line with an implied rest-frame equivalent width of EW_0 (H$\\beta$ + [OIII]) $\\gtrsim 2000$\\AA. Furthermore, we find that new near-infrared data from the UltraVISTA survey supports a weaker He II 1640 emission line than previously measured, with EW_0 $= 40 \\pm 30$\\AA. For the fainter components of CR7 visible in Hubble Space Telescope imaging, we find no evi...

  10. Relationships between the HI 21-cm line strength, MgII equivalent width and metallicity in damped Lyman-alpha absorption systems

    CERN Document Server

    Curran, S J; Pihlström, Y M; Webb, J K

    2007-01-01

    We present the results of a survey for 21-cm absorption in four never previously searched damped Lyman-alpha absorption systems (DLAs) with the Westerbork Synthesis Radio Telescope. We add our results to other recent studies in order to address the important issues regarding the detection of cold gas, through 21-cm absorption, in DLAs: Although, due to the DLAs identified with spiral galaxies, there is a mix of spin temperature/covering factor ratios at low redshift, two recent high redshift end points confirm that this ratio does not generally rise over the whole redshift range searched (up to z = 3.39). That is, if the covering factors of many of these galaxies were a factor of >2 smaller than for the spirals, then no significant difference in the spin temperatures between these two classes would be required. Furthermore, although it is difficult to separate the relative contributions of the spin temperature and covering factor, the new results confirm that 21-cm detections tend to occur at low angular diam...

  11. The explosion energy of early stellar populations: The Fe-peak element ratios in low metallicity damped Lyman-alpha systems

    CERN Document Server

    Cooke, Ryan; Jorgenson, Regina A; Murphy, Michael T; Rudie, Gwen C; Steidel, Charles C

    2012-01-01

    The relative abundances of the Fe-peak elements (Ti-Zn) at the lowest metallicities are intimately linked to the physics of core-collapse supernova explosions. With a sample of 25 very metal-poor damped Lyman-alpha systems, we investigate the trends of the Fe-peak element ratios with metallicity. For nine of the 25 DLAs, a direct measurement (or useful upper limit) of one or more of the Ti,Cr,Co,Ni,Zn/Fe abundance ratios could be determined from detected absorption lines. For the remaining systems (without detections), we devised a new form of spectral stacking to estimate the typical Fe-peak element ratios of the DLA population in this metallicity regime. We compare these data to analogous measurements in metal-poor stars of the Galactic halo and to detailed calculations of explosive nucleosynthesis in metal-free stars. We conclude that most of the DLAs in our sample were enriched by stars that released an energy of < 3.0x10^51 erg when they exploded as core-collapse supernovae. We find one DLA that appea...

  12. C IV absorption in damped and sub-damped Lyman-alpha systems: correlations with metallicity and implications for galactic winds at z~2-3

    CERN Document Server

    Fox, Andrew J; Petitjean, Patrick; Srianand, Raghunathan

    2007-01-01

    We present a study of C IV absorption in a sample of 63 damped Lyman-alpha (DLA) systems and 11 sub-DLAs in the redshift range 1.75

  13. HI 21cm emission from the sub-damped Lyman-alpha absorber at z=0.0063 towards PG1216+069

    CERN Document Server

    Chengalur, Jayaram N; Salter, C J; Kanekar, N; Momjian, E; Keeney, B A; Stocke, J T

    2015-01-01

    We present HI 21cm emission observations of the z ~ 0.00632 sub-damped Lyman-alpha absorber (sub-DLA) towards PG1216+069 made using the Arecibo Telescope and the Very Large Array (VLA). The Arecibo 21cm spectrum corresponds to an HI mass of ~ 3.2x10^7 solar masses, two orders of magnitude smaller than that of a typical spiral galaxy. This is surprising since in the local Universe the cross-section for absorption at high HI column densities is expected to be dominated by spirals. The 21cm emission detected in the VLA spectral cube has a low signal-to-noise ratio, and represents only half the total flux seen at Arecibo. Emission from three other sources is detected in the VLA observations, with only one of these sources having an optical counterpart. This group of HI sources appears to be part of complex "W", believed to lie in the background of the Virgo cluster. While several HI cloud complexes have been found in and around the Virgo cluster, it is unclear whether the ram pressure and galaxy harassment proces...

  14. Lyman-\\alpha{} Emitters in the context of hierarchical galaxy formation: predictions for VLT/MUSE surveys

    CERN Document Server

    Garel, Thibault; Blaizot, Jérémy

    2015-01-01

    The VLT Multi Unit Spectroscopic Explorer (MUSE) integral-field spectrograph can detect Ly\\alpha{} emitters (LAE) in the redshift range $2.8 \\lesssim z \\lesssim 6.7$ in a homogeneous way. Ongoing MUSE surveys will notably probe faint Ly\\alpha{} sources that are usually missed by current narrow-band surveys. We provide quantitative predictions for a typical wedding-cake observing strategy with MUSE based on mock catalogs generated with a semi-analytic model of galaxy formation coupled to numerical Ly\\alpha{} radiation transfer models in gas outflows. We expect $\\approx$ 1500 bright LAEs ($F_{Ly\\alpha}$ $\\gtrsim$ $10^{-17}$ erg s$^{-1}$ cm$^{-2}$) in a typical Shallow Field (SF) survey carried over $\\approx$ 100 arcmin$^2$, and $\\approx$ 2,000 sources as faint as $10^{-18}$ erg s$^{-1}$ cm$^{-2}$ in a Medium-Deep Field (MDF) survey over 10 arcmin$^2$. In a typical Deep Field (DF) survey of 1 arcmin$^2$, we predict that $\\approx$ 500 extremely faint LAEs ($F_{Ly\\alpha}$ $\\gtrsim$ $4 \\times 10^{-19}$ erg s$^{-1}$...

  15. The Stacked Lyman-Alpha Emission Profile from the Circum-Galactic Medium of z~2 Quasars

    CERN Document Server

    Battaia, Fabrizio Arrigoni; Cantalupo, Sebastiano; Prochaska, J Xavier

    2016-01-01

    In the context of the FLASHLIGHT survey, we obtained deep narrow band images of 15 $z\\sim2$ quasars with GMOS on Gemini-South in an effort to measure Ly$\\alpha$ emission from circum- and inter-galactic gas on scales of hundreds of kpc from the central quasar. We do not detect bright giant Ly$\\alpha$ nebulae (SB~10$^{-17}$ erg s$^{-1}$ cm$^{-2}$ arcsec$^{-2}$ at distances >50 kpc) around any of our sources, although we routinely ($\\simeq47$%) detect smaller scale <50 kpc Ly$\\alpha$ emission at this SB level emerging from either the extended narrow emission line regions powered by the quasars or by star-formation in their host galaxies. We stack our 15 deep images to study the average extended Ly$\\alpha$ surface brightness profile around $z\\sim2$ quasars, carefully PSF-subtracting the unresolved emission component and paying close attention to sources of systematic error. Our analysis, which achieves an unprecedented depth, reveals a surface brightness of SB$_{\\rm Ly\\alpha}\\sim10^{-19}$ erg s$^{-1}$ cm$^{-2}...

  16. Inferring the IGM thermal history during reionisation with the Lyman-$\\alpha$ forest power spectrum at redshift $z \\simeq 5$

    CERN Document Server

    Nasir, Fahad; Becker, George D

    2016-01-01

    We use cosmological hydrodynamical simulations to assess the feasibility of constraining the thermal history of the intergalactic medium during reionisation with the Ly$\\alpha$ forest at $z \\simeq 5$. Pressure smoothing has a measurable impact on the transmitted flux power spectrum that can be isolated from Doppler broadening at this redshift. We parameterise the effect of pressure smoothing on the power spectrum using the cumulative energy per proton, $u_0$, deposited into a gas parcel at the mean background density, a quantity that is tightly linked with the integrated thermal history and the gas density power spectrum in the simulations. We construct mock observations of the line of sight Ly$\\alpha$ forest power spectrum and use a Markov Chain Monte Carlo approach to recover $u_{0}$ at redshifts $5 \\leq z \\leq 12$. A statistical uncertainty of $\\sim 20$ per cent is expected (at 68 per cent confidence) at $z\\simeq 5$ using high resolution spectra with a total redshift path length of $\\Delta z=4$ and a typic...

  17. Mock Quasar-Lyman-{\\alpha} Forest Data-sets for the SDSS-III Baryon Oscillation Spectroscopic Survey

    CERN Document Server

    Bautista, Julian E; Font-Ribera, Andreu; Pieri, Matthew M; Busca, Nicolás G; Miralda-Escudé, Jordi; Palanque-Delabrouille, Nathalie; Rich, James; Dawson, Kyle; Feng, Yu; Ge, Jian; Gontcho, Satya Gontcho A; Ho, Shirley; Goff, Jean Marc Le; Noterdaeme, Pasquier; Pâris, Isabelle; Rossi, Graziano; Schlegel, David

    2014-01-01

    We describe mock data-sets generated to simulate the high-redshift quasar sample in Data Release 11 (DR11) of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). The mock spectra contain Ly{\\alpha} forest correlations useful for studying the 3D correlation function including Baryon Acoustic Oscillations (BAO). They also include astrophysical effects such as quasar continuum diversity and high-density absorbers, instrumental effects such as noise and spectral resolution, as well as imperfections introduced by the SDSS pipeline treatment of the raw data. The Ly{\\alpha} forest BAO analysis of the BOSS collaboration, described in Delubac et al. 2014, has used these mock data-sets to develop and cross-check analysis procedures prior to performing the BAO analysis on real data, and for continued systematic cross checks. Tests presented here show that the simulations reproduce sufficiently well important characteristics of real spectra. These mock data-sets will be made available together with the data at t...

  18. Far ultraviolet imaging from the IMAGE spacecraft. 3. Spectral imaging of Lyman-alpha and OI 135.6 nm

    OpenAIRE

    Mende, S. B.; Heetderks, H.; H. U. Frey; Stock, J. M.; Lampton, M.; Geller, S. P.; Abiad, R.; Siegmund, O. H. W.; Habraken, Serge; Renotte, Etienne; Jamar, Claude; Rochus, Pierre; Gérard, Jean-Claude; Sigler, R.; Lauche, H.

    2000-01-01

    Two FUV Spectral imaging instruments, the Spectrographic Imager (SI) and the Geocorona Photometer (GEO) provide IMAGE with simultaneous global maps of the hydrogen (121.8 nm) and oxygen 135.6 nm components of the terrestrial aurora and with observations of the three dimensional distribution of neutral hydrogen in the magnetosphere (121.6 nm). The SI is a novel instrument type, in which spectral separation and imaging functions are independent of each other. In this instrument, two-dimensional...

  19. Electron impact excitation of H2 - Rydberg band systems and the benchmark dissociative cross section for H Lyman-alpha

    Science.gov (United States)

    Shemansky, D. E.; Hall, D. T.; Ajello, J. M.

    1985-01-01

    The cross sections sigma R 1 (2p) for excitation of H Ly-alpha emission produced by electron impact on H2 is reexamined. A more accurate estimate for sigma R 1 (2p) is obtained based on Born approximation estimates of the H2 Rydberg system cross sections using measured relative excitation functions. The obtained value is (8.18 + or -1.2) x 10 to the -18th sq cm at 100 eV, a factor of 0.69 below the value universally applied to cross section measurements over the past decade. Cross sections for the H2 Rydberg systems fixed in magnitude by the Born approximation have also been obtained using experimentally determined excitation functions. Accurate analytic expressions for these cross sections allow the direct calculation of rate coefficients.

  20. Galaxy Group at z=0.3 Associated with the Damped Lyman Alpha System Towards Quasar Q1127-145

    CERN Document Server

    Kacprzak, G G; Churchill, C W

    2010-01-01

    We performed a spectroscopic galaxy survey, complete to $m_{F814W}\\leq20.3$ ($L_B>0.15L_B^{\\star}$ at z=0.3), within 100x100'' of the quasar Q1127-145 ($z_{em}=1.18$). The VLT/UVES quasar spectrum contains three $z_{abs}<0.33$ MgII absorption systems. We obtained eight new galaxy redshifts, adding to the four previously known, and galaxy star formation rates (SFRs) and metallicities were computed where possible. A strong MgII system [$W_r(2796)=1.8$A], which is a known damped Ly$\\alpha$ absorber (DLA), had three previously identified galaxies; we found two additional galaxies associated with this system. These five galaxies form a group with diverse properties, such as a luminosity range of $0.04\\leq L_B\\leq0.63 L_B^{\\star}$, an impact parameter range of $17\\leq D \\leq 241$ kpc and velocity dispersion of $\\sigma$=115 km/s. The DLA group galaxy redshifts span beyond the 350 km/s velocity spread of the metallic absorption lines of the DLA itself. The two brightest group galaxies have SFRs of $\\sim$few $M_{\\o...

  1. Discovery of Massive, Mostly Star-formation Quenched Galaxies with Extremely Large Lyman-alpha Equivalent Widths at z ~ 3

    CERN Document Server

    Taniguchi, Yoshiaki; Kobayashi, Masakazu A R; Nagao, Tohru; Shioya, Yasuhiro; Scoville, Nick Z; Sanders, David B; Capak, Peter L; Koekemoer, Anton M; Toft, Sune; McCracken, Henry J; Fevre, Olivier Le; Tasca, Lidia; Sheth, Kartik; Renzini, Alvio; Lilly, Simon; Carollo, Marcella; Kovac, Katarina; Ilbert, Olivier; Schinnerer, Eva; Fu, Hai; Tresse, Laurence; Griffiths, Richard E; Civano, Francesca

    2015-01-01

    We report a discovery of 6 massive galaxies with both extremely large Lya equivalent width and evolved stellar population at z ~ 3. These MAssive Extremely STrong Lya emitting Objects (MAESTLOs) have been discovered in our large-volume systematic survey for strong Lya emitters (LAEs) with twelve optical intermediate-band data taken with Subaru/Suprime-Cam in the COSMOS field. Based on the SED fitting analysis for these LAEs, it is found that these MAESTLOs have (1) large rest-frame equivalent width of EW_0(Lya) ~ 100--300 A, (2) M_star ~ 10^10.5--10^11.1 M_sun, and (3) relatively low specific star formation rates of SFR/M_star ~ 0.03--1 Gyr^-1. Three of the 6 MAESTLOs have extended Ly$\\alpha$ emission with a radius of several kpc although they show very compact morphology in the HST/ACS images, which correspond to the rest-frame UV continuum. Since the MAESTLOs do not show any evidence for AGNs, the observed extended Lya emission is likely to be caused by star formation process including the superwind activit...

  2. The ALFALFA HI Absorption Pilot Survey: A Wide-Area Blind Damped Lyman Alpha System Survey of the Local Universe

    CERN Document Server

    Darling, Jeremy; Haynes, Martha P; Giovanelli, Riccardo

    2011-01-01

    We present the results of a pilot survey for neutral hydrogen (HI) 21 cm absorption in the Arecibo Legacy Fast Arecibo L-Band Feed Array (ALFALFA) Survey. This project is a wide-area "blind" search for HI absorption in the local universe, spanning -650 km/s = 2x10^20 cm^-2) is Delta z = 7.0 (129 objects, assuming T_s = 100 K and covering fraction unity); for super-DLAs (N_HI >= 2x10^21 cm^-2) it is Delta z= 128.2 (2353 objects). We re-detect the intrinsic HI absorption line in UGC 6081 but detect no intervening absorption line systems. We compute a 95% confidence upper limit on the column density frequency distribution function f(N_HI,X) spanning four orders of magnitude in column density, 10^19 (T_s/100 K)(1/f) cm^-2 < N_HI < 10^23 (T_s/100 K)(1/f) cm^-2, that is consistent with previous redshifted optical damped Ly alpha surveys and the aggregate HI 21 cm emission in the local universe. The detection rate is in agreement with extant observations. This pilot survey suggests that an absorption line sear...

  3. A search for H$\\alpha$ emission in high-metallicity damped Lyman-$\\alpha$ systems at $z \\sim 2.4$

    CERN Document Server

    Wang, Wei-Hao; Prochaska, J Xavier

    2015-01-01

    We report on a sensitive search for redshifted H$\\alpha$ line-emission from three high-metallicity damped Ly$\\alpha$ absorbers (DLAs) at $z \\approx 2.4$ with the Near-infrared Integral Field Spectrometer (NIFS) on the Gemini-North telescope, assisted by the ALTtitude conjugate Adaptive optics for the InfraRed (ALTAIR) system with a laser guide star. Within the NIFS field-of-view, $\\approx 3.22" \\times 2.92"$ corresponding to $\\approx 25$ kpc $ \\times 23$ kpc at $z=2.4$, we detect no statistically significant line-emission at the expected redshifted H$\\alpha$ wavelengths. The measured root-mean-square noise fluctuations in $0.4"$ apertures are $1-3\\times10^{-18}$ erg s$^{-1}$ cm$^{-2}$. Our analysis of simulated, compact, line-emitting sources yields stringent limits on the star-formation rates (SFRs) of the three DLAs, $< 2.2$~M$_{\\odot}$ yr$^{-1}$ ($3\\sigma$) for two absorbers, and $< 11$~M$_{\\odot}$ yr$^{-1}$ ($3\\sigma$) for the third, at all impact parameters within $\\approx 12.5$~kpc to the quasar s...

  4. Final Scientific/Technical Report, DE-FG02-08ER41561: "Lyman-alpha Emitting Galaxies at 2

    Energy Technology Data Exchange (ETDEWEB)

    Eric Gawiser

    2010-03-19

    Lyman Alpha Emitting (LAE) galaxies are a powerful tracer of large scale structure, making them an excellent probe of baryonic acoustic oscillations, which constrain the expansion history of the universe and hence the nature of the dark energy. The HETDEX Stage III dark energy experiment will utilize LAEs for this purpose, and they are under consideration as a tracer of structure for Stage IV ground- and space-based dark energy missions. Our successful investigation of LAEs at z=2.1 and z=3.1 now provides the best information on the number density and clustering bias of these galaxies over the redshift range that HETDEX will study. Connecting these star-forming galaxies to their host dark matter halos represents a major increase in scientific understanding, as we can now proceed with confidence in studying the spatial distribution of significantly larger samples. Our data also provided an empirical test of the Lyman Alpha Tomography technique, which has proven effective and can now be used to design future experiments to probe dark energy and dark matter properties.

  5. Voids in Ly{\\alpha} Forest Tomographic Maps

    CERN Document Server

    Stark, Casey W; White, Martin; Lee, Khee-Gan

    2015-01-01

    We present a new method of finding cosmic voids using tomographic maps of Ly{\\alpha} forest flux. We identify cosmological voids with radii of 2 - 12 $h^{-1}$Mpc in a large N-body simulation at $z = 2.5$, and characterize the signal of the high-redshift voids in density and Ly{\\alpha} forest flux. The void properties are similar to what has been found at lower redshifts, but they are smaller and have steeper radial density profiles. Similarly to what has been found for low-redshift voids, the radial velocity profiles have little scatter and agree very well with the linear theory prediction. We run the same void finder on an ideal Ly{\\alpha} flux field and tomographic reconstructions at various spatial samplings. We compare the tomographic map void catalogs to the density void catalog and find good agreement even with modest-sized voids ($r > 6 \\, h^{-1}$Mpc). Using our simple void-finding method, the configuration of the ongoing CLAMATO survey covering 1 deg$^2$ would provide a sample of about 100 high-redshi...

  6. Efficient quality enhancement of disparity maps based on alpha matting

    Science.gov (United States)

    Brosch, Nicole; Nezveda, Matej; Gelautz, Margrit; Seitner, Florian

    2014-03-01

    We propose an efficient disparity map enhancement method that improves the alignment of disparity edges and color edges even in the presence of mixed pixels and provides alpha values for pixels at disparity edges as a byproduct. In contrast to previous publications, the proposed method addresses mixed pixels at disparity edges and does not introduce mixed disparities that can lead to object deformations in synthesized views. The proposed algorithm computes transparencies by performing alpha matting per disparity-layer. These alpha values indicate the degree of affiliation to a disparity-layer and can hence be used as an indicator for a disparity reassignment that aligns disparity edges with color edges and accounts for mixed pixels. We demonstrate the capabilities of the proposed method on various images and corresponding disparity maps, including images that contain fuzzy object borders (e.g., fur). Furthermore, the proposed method is qualitatively and quantitatively evaluated using disparity ground truth and compared to previously published disparity post-processing methods.

  7. Observational challenges in Ly-alpha intensity mapping

    CERN Document Server

    Comaschi, Paolo; Ferrara, Andrea

    2016-01-01

    Intensity mapping (IM) is sensitive to the cumulative line emission of galaxies. As such it represents a promising technique for statistical studies of galaxies fainter than the limiting magnitude of traditional galaxy surveys. The strong hydrogen Ly-alpha line is the primary target for such an experiment, as its intensity is linked to star formation activity and the physical state of the interstellar (ISM) and intergalactic (IGM) medium. However, to extract the meaningful information one has to solve the confusion problems caused by interloping lines from foreground galaxies. We discuss here the challenges for a Ly-alpha IM experiment targeting z > 4 sources. We find that the Ly-alpha power spectrum can be in principle easily (marginally) obtained with a 40 cm space telescope in a few days of observing time up to z < 8 (z = 10) assuming that the interloping lines (e.g. H-alpha, [O II], [O III] lines) can be efficiently removed. We show that interlopers can be removed by using an ancillary photometric gala...

  8. Mapping alpha-Particle X-Ray Fluorescence Spectrometer (Map-X)

    Science.gov (United States)

    Blake, D. F.; Sarrazin, P.; Bristow, T.

    2014-01-01

    Many planetary surface processes (like physical and chemical weathering, water activity, diagenesis, low-temperature or impact metamorphism, and biogenic activity) leave traces of their actions as features in the size range 10s to 100s of micron. The Mapping alpha-particle X-ray Spectrometer ("Map-X") is intended to provide chemical imaging at 2 orders of magnitude higher spatial resolution than previously flown instruments, yielding elemental chemistry at or below the scale length where many relict physical, chemical, and biological features can be imaged and interpreted in ancient rocks.

  9. Galaxy counterparts of metal-rich damped Lyman-alpha absorbers - II. A solar-metallicity, molecular-rich, and dusty DLA at z_abs=2.58

    CERN Document Server

    Fynbo, J P U; Noterdaeme, P; Christensen, L; Moller, P; Durgapal, A K; Goldoni, P; Kaper, L; Krogager, J -K; Laursen, P; Maund, J R; Milvang-Jensen, B; Okoshi, K; Rasmussen, P K; Thorsen, T J; Toft, S; Zafar, T

    2010-01-01

    [Abridged]. Here, we report on the discovery of the galaxy counterpart of the z_abs=2.58 DLA on the line-of-sight to the z=3.07 quasar SDSS J091826.16+163609.0. The galaxy counterpart of the DLA is detected in the OIII 5007 and OII 3726,3729 emission lines redshifted into the NIR at an impact parameter of 16 kpc. Ly-alpha emission is not detected. The upper limit implies that Ly-alpha emission from this galaxy is suppressed by more than an order of magnitude. The DLA is amongst the most metal-rich DLAs studied so far at comparable redshifts. We find evidence for substantial depletion of refractory elements onto dust grains. Fitting the main metal line component of the DLA, which is located at z_abs=2.5832 and accounts for at least 85% of the total column density of low-ionisation species, we measure metal abundances from ZnII, SII, SiII, CrII, MnII, FeII and NiII of -0.12, -0.26, -0.46, -0.88, -0.92, -1.03 and -0.78, respectively. In addition, we detect absorption in the Lyman and Werner bands of hydrogen, wh...

  10. Discovery of an Overdensity of Lyman-alpha Emitters Around a $\\mathrm{z}\\sim4$ QSO with the Large Binocular Telescope

    CERN Document Server

    Adams, Scott M; Croxall, Kevin V; Overzier, Roderik A; Silverman, John D

    2014-01-01

    Measurements of QSO clustering in the SDSS show that $\\mathrm{z}>4$ QSOs are some of the most highly biased objects in the universe. Their large correlation lengths of $r_0 \\sim 20h^{-1}$Mpc are comparable to the most massive clusters of galaxies in the universe today and suggest that these QSOs may mark the locations of massive cluster progenitors at high redshift. We report the discovery of an overdensity of LBGs around QSO SDSSJ114514.18+394715.9 as part of our survey to identify Lyman-Break galaxies (LBGs) around luminous $\\mathrm{z}\\sim4$ QSOs. In this field three of the eight LBGs with secure redshifts are consistent with the redshift of the QSO. We find that the likelihood that this is merely an apparent overdensity due to the chance selection of field galaxies is only 0.02%, based on comparisons to simulations and our modeled selection efficiency. Overall, our survey finds four of the 15 LBGs with secure redshifts are consistent with the redshifts of their respective QSOs, which is consistent with lum...

  11. MgII Absorption Lines in z=2.974 Damped Lyman-alpha System toward Gravitationally Lensed QSO APM 08279+5255 Detection of Small-scale Structure in MgII Absorbing Clouds

    CERN Document Server

    Kobayashi, N; Goto, M; Tokunaga, A; Kobayashi, Naoto; Terada, Hiroshi; Goto, Miwa; Tokunaga, Alan

    2002-01-01

    1.02-1.16 micron spectra (R ~ 7,000) of the gravitationally lensed QSO APM 08279+5255 at z_em=3.911 were obtained during the commissioning run of IRCS, the 1-5 micron near-infrared camera and spectrograph for the Subaru 8.2 m Telescope. Strong MgII doublet at 2976,2800 angstrom and FeII (2600 angstrom), FeII (2587 angstrom) absorption lines at z_abs=2.974 were clearly detected in the rest-frame UV spectra, confirming the presence of a damped Lyman-alpha system at the redshift as suggested by Petitjean et al. Also MgI (2853 angstrom) absorption line is probably detected. An analysis of the absorption lines including velocity decomposition was performed. This is a first detailed study of MgII absorption system at high redshift (z > 2.5) where the MgII doublet shifts into the near-infrared in the observer's frame. The spectra of the lensed QSO pair A and B with 0.38 arcsec separation were resolved in some exposure frames under excellent seeing condition. We extracted the MgII doublet spectra of A and B separatel...

  12. High Precision Analyses of Lyman alpha Damping Wing of Gamma-Ray Bursts in the Reionization Era: On the Controversial Results from GRB 130606A at z = 5.91

    CERN Document Server

    Totani, Tomonori; Hattori, Takashi; Kawai, Nobuyuki

    2015-01-01

    The unprecedentedly bright afterglow of GRB 130606A at z = 5.91 gave us a unique opportunity to probe the reionization era by high precision analyses of the redward damping wing of Lyman alpha absorption, but the reported constraints on the neutral hydrogen fraction (f_{HI}) in intergalactic medium (IGM) derived from spectra taken by different telescopes are in contradiction. Here we examine the origin of this discrepancy by analyzing the spectrum taken by VLT with our own analysis code previously used to fit the Subaru spectrum. Though the VLT team reported no evidence for IGM HI using the VLT spectrum, we confirmed our previous result of 3-4 sigma preference for non-zero IGM HI (f_{HI} ~ 0.06, when IGM HI extends to the GRB redshift). The fit residuals of the VLT spectrum by the model without IGM HI show the same systematic trend as the Subaru spectrum. We consider that the likely origin of the discrepancy between the two teams is the difference of the wavelength ranges adopted in the fittings; our waveleng...

  13. Detection of Lyman-Alpha Emission From a Triple Imaged z=6.85 Galaxy Behind MACS J2129.4-0741

    CERN Document Server

    Huang, Kuang-Han; Schmidt, Kasper B; Hoag, Austin; Bradač, Maruša; Treu, Tommaso; Dijkstra, Mark; Fontana, Adriano; Henry, Alaina; Malkan, Matthew; Mason, Charlotte; Morishita, Takahiro; Pentericci, Laura; Ryan, Russell E; Trenti, Michele; Wang, Xin

    2016-01-01

    We report the detection of Ly$\\alpha$ emission at $\\sim9538$\\AA{} in the Keck/DEIMOS and \\HST WFC3 G102 grism data from a triply-imaged galaxy at $z=6.846\\pm0.001$ behind galaxy cluster MACS J2129.4$-$0741. Combining the emission line wavelength with broadband photometry, line ratio upper limits, and lens modeling, we rule out the scenario that this emission line is \\oii at $z=1.57$. After accounting for magnification, we calculate the weighted average of the intrinsic Ly$\\alpha$ luminosity to be $\\sim1.3\\times10^{42}~\\mathrm{erg}~\\mathrm{s}^{-1}$ and Ly$\\alpha$ equivalent width to be $74\\pm15$\\AA{}. Its intrinsic UV absolute magnitude at 1600\\AA{} is $-18.6\\pm0.2$ mag and stellar mass $(1.5\\pm0.3)\\times10^{7}~M_{\\odot}$, making it one of the faintest (intrinsic $L_{UV}\\sim0.14~L_{UV}^*$) galaxies with Ly$\\alpha$ detection at $z\\sim7$ to date. Its stellar mass is in the typical range for the galaxies thought to dominate the reionization photon budget at $z\\gtrsim7$; the inferred Ly$\\alpha$ escape fraction is ...

  14. Keck/MOSFIRE Spectroscopy of z=7-8 Galaxies: Lyman-alpha Emission from a Galaxy at z=7.66

    CERN Document Server

    Song, Mimi; Livermore, Rachael C; Capak, Peter L; Dickinson, Mark; Fontana, Adriano

    2016-01-01

    We report the results from some of the deepest Keck/MOSFIRE data yet obtained for candidate $z \\gtrsim 7$ galaxies. Our data show one significant line detection with 6.5$\\sigma$ significance in our combined 10 hours of integration which is independently detected on more than one night, ruling out the possibility that the detection is spurious. The asymmetric line profile and non-detection in the optical bands strongly imply that the detected line is Ly$\\alpha$ emission from a galaxy at $z$(Ly$\\alpha)=7.6637 \\pm 0.0011$, making it the fourth spectroscopically confirmed galaxy at $z>7.5$. This galaxy is bright in the rest-frame ultraviolet (UV; $M_{\\rm UV} \\sim -21.2$) with a moderately blue UV slope ($\\beta=-2.2^{+0.3}_{-0.2}$), and exhibits a rest-frame Ly$\\alpha$ equivalent width of EW(Ly$\\alpha$) $\\sim 15.6^{+5.6}_{-3.6}$ \\AA. The non-detection of the 11 other $z \\sim$ 7--8 galaxies in our long 10 hr integration, reaching a median 5$\\sigma$ sensitivity of 28 \\AA\\ in the rest-frame EW(Ly$\\alpha$), implies a ...

  15. Lyman α emission from the first galaxies: signatures of accretion and infall in the presence of line trapping

    NARCIS (Netherlands)

    Latif, M. A.; Schleicher, Dominik R. G.; Spaans, M.; Zaroubi, S.

    2011-01-01

    The formation of the first galaxies is accompanied by large accretion flows and virialization shocks, during which the gas is shock heated to temperatures of similar to 10(4) K, leading to potentially strong fluxes in the Lyman alpha line. Indeed, a number of Lyman alpha blobs have been detected at

  16. Lyman α emission from the first galaxies: signatures of accretion and infall in the presence of line trapping

    NARCIS (Netherlands)

    Latif, M. A.; Schleicher, Dominik R. G.; Spaans, M.; Zaroubi, S.

    The formation of the first galaxies is accompanied by large accretion flows and virialization shocks, during which the gas is shock heated to temperatures of similar to 10(4) K, leading to potentially strong fluxes in the Lyman alpha line. Indeed, a number of Lyman alpha blobs have been detected at

  17. ALMA observations of a z~3.1 Protocluster: Star Formation from Active Galactic Nuclei and Lyman-Alpha Blobs in an Overdense Environment

    CERN Document Server

    Alexander, D M; Harrison, C M; Mullaney, J R; Smail, I; Geach, J E; Hickox, R C; Hine, N K; Karim, A; Kubo, M; Lehmer, B D; Matsuda, Y; Rosario, D J; Stanley, F; Swinbank, A M; Umehata, H; Yamada, T

    2016-01-01

    We exploit ALMA 870um observations to measure the star-formation rates (SFRs) of eight X-ray detected Active Galactic Nuclei (AGNs) in a z~3.1 protocluster, four of which reside in extended Ly-alpha haloes (often termed Ly-alpha blobs: LABs). Three of the AGNs are detected by ALMA and have implied SFRs of ~220-410~M_sun/yr; the non detection of the other five AGNs places SFR upper limits of 100 kpc) do not host more luminous star formation than the smaller LABs, despite being an order of magnitude brighter in Ly-alpha emission. We use these results to discuss star formation as the power source of LABs.

  18. Dust-to-metal ratios in Damped Lyman-alpha absorbers: Fresh clues to the origins of dust and optical extinction towards gamma-ray bursts

    CERN Document Server

    De Cia, A; Savaglio, S; Schady, P; Vreeswijk, P M

    2013-01-01

    Motivated by the anomalous dust-to-metal ratios (DTM) derived in the literature for gamma-ray burst (GRB) damped Ly-alpha absorbers (DLAs), we measure these ratios using the dust-depletion pattern observed in UV/optical afterglow spectra, associated with the interstellar medium (ISM) at the GRB host-galaxy redshifts. Our sample consists of 20 GRB absorbers and a comparison sample of 72 QSO-DLAs, overall at redshift 1.2 14.7, above which several QSO-DLAs reveal H2, making GRB-DLAs promising candidates for molecular research.

  19. Deep HeII and CIV Spectroscopy of a Giant Lyman alpha Nebula: Dense Compact Gas Clumps in the Circumgalactic Medium of a z~2 Quasar

    CERN Document Server

    Battaia, Fabrizio Arrigoni; Prochaska, J Xavier; Cantalupo, Sebastiano

    2015-01-01

    The recent discovery by Cantalupo et al. (2014) of the largest (~500 kpc) and luminous Ly-alpha nebula associated with the quasar UM287 (z=2.279) poses a great challenge to our current understanding of the astrophysics of the halos hosting massive z~2 galaxies. Either an enormous reservoir of cool gas is required $M\\simeq10^{12}$ $M_{\\odot}$, exceeding the expected baryonic mass available, or one must invoke extreme gas clumping factors not present in high-resolution cosmological simulations. However, observations of Ly-alpha emission alone cannot distinguish between these two scenarios. We have obtained the deepest ever spectroscopic integrations in the HeII and CIV lines with the goal of detecting extended line emission, but detect neither line to a 3$\\sigma$ limiting SB $\\simeq10^{-18}$ erg/s/cm$^2$/arcsec$^2$. We construct models of the expected emission spectrum in the highly probable scenario that the nebula is powered by photoionization from the central hyper-luminous quasar. The non-detection of HeII ...

  20. A New Population of High-z, Dusty Lyman-alpha Emitters and Blobs Discovered by WISE: Feedback Caught in the Act?

    Science.gov (United States)

    Bridge, Carrie R.; Blain, Andrew; Borys, Colin J. K.; Petty, Sara; Benford, Dominic; Eisenhardt, Peter; Farrah, Duncan; Griffith, Roger, L.; Jarrett, Tom; Lonsdale, Carol; hide

    2013-01-01

    By combining data from the NASA Wide-field Infrared Survey Explorer (WISE) mission with optical spectroscopy from the W. M. Keck telescope, we discover a mid-IR color criterion that yields a 78% success rate in identifying rare, typically radio-quiet, 1.6 approx. 10(exp 13)-10(exp 14) Solar L) and have warm colors. They are typically more luminous and warmer than other dusty, z approx.. 2 populations such as submillimeter-selected galaxies and dust-obscured galaxies. These traits are commonly associated with the dust being illuminated by intense active galactic nucleus activity. We hypothesize that the combination of spatially extended Ly-alpha, large amounts of warm IR-luminous dust, and rarity (implying a short-lived phase) can be explained if the galaxies are undergoing brief, intense "feedback" transforming them from an extreme dusty starburst/QSO into a mature galaxy.

  1. A SINFONI Integral Field Spectroscopy Survey for Galaxy Counterparts to Damped Lyman-alpha Systems - VI. Metallicity and Geometry as Gas Flow Probes

    CERN Document Server

    Peroux, Celine; Rahmani, Hadi; Kulkarni, Varsha P; Epinat, Benoit; Milliard, Bruno; Straka, Lorrie; York, Donald G; Rahmati, Alireza; Contini, Thierry

    2016-01-01

    The use of background quasars provides a powerful tool to probe the cool gas in the circum-galactic medium of foreground galaxies. Here, we present new observations with SINFONI and X-Shooter of absorbing-galaxy candidates at z=0.7-1. We report the detection with both instruments of the H-alpha emission line of one sub-DLA at z_abs=0.94187 with log N(HI)=19.38^+0.10_-0.15 towards SDSS J002133.27+004300.9. We estimate the star formation rate: SFR=3.6+/-2.2 solar masses per year in that system. A detailed kinematic study indicates a dynamical mass M_dyn=10^9.9+/-0.4 solar masses and a halo mass M_halo=10^11.9+/-0.5 solar masses. In addition, we report the OII detection with X-Shooter of another DLA at z_abs=0.7402 with log N(HI)=20.4+/-0.1 toward Q0052+0041 and an estimated SFR of 5.3+/-0.7 solar masses per year. Three other objects are detected in the continuum with X-Shooter but the nature and redshift of two of these objects are unconstrained due to the absence of emission lines, while the third object might...

  2. Lyman-Alpha-Emitting Galaxies at z = 2.1 in ECDF-S: Building Blocks of Typical Present-day Galaxies?

    CERN Document Server

    Guaita, L; Padilla, N; Francke, H; Bond, N A; Gronwall, C; Ciardullo, R; Feldmeier, J J; Sinawa, S; Blanc, G A; Virani, S

    2009-01-01

    We discovered a sample of 261 Ly-Alpha emitting (LAE) galaxies at z=2.1 in an ultra-deep 3727 A narrow-band MUSYC image of the Extended Chandra Deep Field-South. LAEs were selected to have rest-frame equivalent widths (EW) >20 A and emission line fluxes F>2.0 x 10^(-17)erg /cm^2/s, after carefully subtracting the continuum contributions from narrow band photometry. The median flux of our sample is F = 4.1 x 10^(-17)erg/cm^2/s, corresponding to a median Lya luminosity = 1.3 x 10^(42) erg/s at z=2.1. At emission line fluxes F= 3.8 x 10^(-17) erg/cm^2/s our sample is 90% complete. 3% of the original candidates were detected in X-rays by Chandra, and 7% were detected in the rest-frame far-UV by GALEX. The remainder of our sample has median rest-frame EW of 39 A, with only a few galaxies having rest frame EW bigger than 200 A. We find a number density of 3.2+/-0.9 x 10^(-3) Mpc^(-3), a factor of 2.1+/-0.7 increase versus LAEs at z ~ 3. We used the rest frame UV luminosity to estimate a median star formation rate o...

  3. Cosmological adventures in the Lyman forest

    CERN Document Server

    Cristiani, S

    1995-01-01

    The properties of the Lyman-\\alpha absorptions observed in the spectra of QSOs are reviewed: the distribution of column densities and Doppler widths, the redshift evolution, the ``inverse effect'', the clustering. By interpreting the statistics of the line parameters insight is gained about the nature of the absorbers, their sizes, temperatures, confining agents. On the basis of the ``inverse effect'' it is possible to estimate the ultraviolet background radiation at high redshift and, linking this information with the limits on the Gunn-Peterson optical depth, the density of the diffuse part of the intergalactic medium is derived. Future prospects are briefly discussed.

  4. Restriction enzyme mapping of the DNA of Streptomyces bacteriophage B alpha and its deletion derivatives.

    Science.gov (United States)

    Ishihara, H; Nakano, M M; Ogawara, H

    1982-12-01

    Cleavage analysis of actinophage B alpha DNA was done with several restriction enzymes, and a restriction map of the DNA was determined. The DNA appeared to carry cohesive ends. Deletion mutants of actinophage B alpha were isolated by five cycles of treatment with 15 mM PPi. Both mutants had deletions of 2.5 of 1.8 megadaltons near one end of the genome, and one of them lost the single EcoRI cleavage site.

  5. Mapping of a liver phosphorylase kinase [alpha]-subunit gene on the mouse x chromosome

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Yan; Derry, J.M.J.; Barnard, P.J. (MRC Molecular Neurobiology Unit, Cambridge (United Kingdom)); Hendrickx, J.; Coucke, P.; Willems, P.R. (Univ. of Antwerp (Belgium))

    1993-01-01

    Phosphorylase kinase (PHK) is a regulatory enzyme of the glycogenolytic pathway composed of a complex of four subunits. We recently mapped the muscle [alpha]-subunit gene (Phka) to the mouse X chromosome in a region syntenic with the proximal long arm of the human X chromosome and containing the human homologue of this gene, PHKA. We now report the mapping of the liver [alpha]-subunit gene to the telomeric end of the mouse X chromosome. This mapping position would suggest a location for the human liver [alpha]-subunit gene on the proximal short arm of the X chromosome, a region recently implicated in X-linked liver glycogenosis (XLG). 20 refs., 2 figs.

  6. Foreground contamination in Ly-alpha intensity mapping during the epoch of reionization

    CERN Document Server

    Gong, Yan; Cooray, Asantha; Santos, Mario G

    2013-01-01

    The intensity mapping of Ly-alpha emission during the epoch of reionization (EoR) will be contaminated by foreground emission lines from lower redshifts. We calculate the mean intensity and power spectrum of Ly-alpha emission at z~7, and estimate the uncertainties according to the relevant astrophysical processes. We find that the low-redshift emission lines from 6563 A H-alpha, 5007 A [OIII] and 3727 A [OII] will be the strong contaminants on the observed Ly-alpha power spectrum. We make use of both the star formation rate (SFR) and luminosity functions (LF) to estimate the mean intensity and power spectra of the three foreground lines at z~0.5 for H-alpha, z~0.9 for [OIII] and z~1.6 for [OII], as they will contaminate the Ly-alpha emission at z~7. The [OII] line is found to be the strongest. We analyze the masking of the bright survey pixels with a foreground line above some line intensity threshold as a way to reduce the contamination in the intensity mapping survey. We find that the foreground contaminati...

  7. Lyman alpha coronagraph research sounding rocket program

    Science.gov (United States)

    Parkinson, W. H.; Kohl, J. L.

    1985-01-01

    The ultraviolet light coronagraph was developed and successfully flown on three rocket flights on 13 April 1979, 16 February 1980 and 20 July 1982. During each of these flights, the Ultraviolet Light Coronagraph was flown jointly with the White Light Coronagraph provided by the High Altitude Observatory. Ultraviolet diagnostic techniques and instrumentation for determining the basic plasma parameters of solar wind acceleration regions in the extended corona were developed and verified and the understanding of the physics of the corona through the performance, analysis and interpretation of solar observations advanced. Valuable UV diagnostics can be performed in the absence of a natural solar eclipse.

  8. PAH Emission Within Lyman Alpha Blobs

    CERN Document Server

    Colbert, James W; Teplitz, Harry; Francis, Paul; Palunas, Povilas; Williger, Gerard M; Woodgate, Bruce

    2010-01-01

    We present Spitzer observations of Lya Blobs (LAB) at z=2.38-3.09. The mid-infrared ratios (4.5/8um and 8/24um) indicate that ~60% of LAB infrared counterparts are cool, consistent with their infrared output being dominated by star formation and not active galactic nuclei (AGN). The rest have a substantial hot dust component that one would expect from an AGN or an extreme starburst. Comparing the mid-infrared to submillimeter fluxes (~850um or rest frame far infrared) also indicates a large percentage (~2/3) of the LAB counterparts have total bolometric energy output dominated by star formation, although the number of sources with sub-mm detections or meaningful upper limits remains small (~10). We obtained Infrared Spectrograph (IRS) spectra of 6 infrared-bright sources associated with LABs. Four of these sources have measurable polycyclic aromatic hydrocarbon (PAH) emission features, indicative of significant star formation, while the remaining two show a featureless continuum, indicative of infrared energy...

  9. First Stars in Damped Lyman Alpha systems

    NARCIS (Netherlands)

    Salvadori, Stefania; Ferrara, Andrea

    In order to characterize Damped Lyα Absorption systems (DLAs) potentially hosting first stars, we present a novel approach to investigate DLAs in the context of Milky Way (MW) formation, along with their connection with the most metal-poor stars and local dwarf galaxies. The model explains the

  10. Fixed points for alpha-psi contractive mappings with an application to quadratic integral equations

    Directory of Open Access Journals (Sweden)

    Bessem Samet

    2014-06-01

    Full Text Available Recently, Samet et al [24] introduced the concept of alpha-psi contractive mappings and studied the existence of fixed points for such mappings. In this article, we prove three fixed point theorems for this class of operators in complete metric spaces. Our results extend the results in [24] and well known fixed point theorems due to Banach, Kannan, Chatterjea, Zamfirescu, Berinde, Suzuki, Ciric, Nieto, Lopez, and many others. We prove that alpha-psi contractions unify large classes of contractive type operators, whose fixed points can be obtained by means of the Picard iteration. Finally, we utilize our results to discuss the existence and uniqueness of solutions to a class of quadratic integral equations.

  11. AKARI/FIS Mapping of the ISM-Wind Bow Shock around Alpha Ori

    CERN Document Server

    Ueta, Toshiya; Yamamura, Issei; Nakada, Yoshikazu; Matsuura, Mikako; Ita, Yoshifusa; Tanabe, Toshihiko; Fukushi, Hinako; Matsunaga, Noriyuki; Mito, Hiroyuki

    2008-01-01

    We present 10' x 50' scan maps around an M supergiant Alpha Ori at 65, 90, 140 and 160 microns obtained with the AKARI Infrared Astronomy Satellite. Higher spatial resolution data with the exact analytic solution permit us to fit the de-projected shape of the stellar wind bow shock around Alpha Ori to have the stand-off distance of 4.8', position angle of 55 degrees and inclination angle of 56 degrees. The shape of the bow shock suggests that the peculiar velocity of Alpha Ori with respect to the local medium is v_* = 40 (n_H)^(-1/2), where n_H is the hydrogen nucleus density at Alpha Ori. We find that the local medium is of n_H = 1.5 to 1.9 cm^(-3) and the velocity of the local flow is at 11 km s^(-1) by using the most recent astrometric solutions for Alpha Ori under the assumption that the local medium is moving away from the Orion OB 1 association. AKARI images may also reveal a vortex ring due to instabilities on the surface of the bow shock as demonstrated by numerical models. This research exemplifies t...

  12. Mapping Neutral Hydrogen During Reionization with the Ly-alpha Emission from Quasar Ionization Fronts

    CERN Document Server

    Cantalupo, Sebastiano; Lilly, Simon J

    2007-01-01

    We present a new method to directly map the neutral-hydrogen distribution during the reionization epoch and to constrain the emission properties of the highest-redshift quasars (QSOs). As a tracer of HI, we propose to use the Ly-alpha radiation produced by quasar ionization fronts (I-fronts) that expand in the partially ionized intergalactic medium (IGM) before reionization is complete. These Ly-alpha photons are mainly generated by collisional excitations of hydrogen atoms in the boundary of the rapidly expanding HII region. The observable signal is produced by the part of the I-front that lies behind the QSO with respect to the observer. Combining two radiative transfer models (one for the QSO ionizing radiation and one for the Ly-alpha photons), we estimate the expected Ly-alpha spectral shape and surface brightness (SB) for a large number of configurations where we varied both the properties of the ionizing QSO and of the surrounding medium. We find that the expected signal is observable as a single (broa...

  13. AGI, a previously unreported D. melanogaster {alpha}-glucosidase: Partial purification, characterization, and cytogenetic mapping

    Energy Technology Data Exchange (ETDEWEB)

    Parker, G.F.; Roberts, D.B. [Univ. of Oxford (United Kingdom)

    1996-04-01

    Inbred Drosophila melanogaster stocks were surveyed for {alpha}-glucosidases with nondenaturing gel electrophoresis using a fluorogenic substrate to stain the gels. The glucosidase most active under these conditions is polymorphic. We established that the polymorphism is genetic in origin and that the glucosidase was not likely to be a previously characterized enzyme. The gene encoding the enzyme was mapped cytogenetically to 33 A1-2- 33A8-B1, confirming that this is an enzyme not yet reported in D. melanogaster. The enzyme was partially purified by elution from nondenaturing gels, which enable us to establish that it has optimal activity at pH 6 and interacts most strongly with {alpha}- 1 -4 glucosides. A developmental and tissue survey suggested that this enzyme could have a purely digestive role or be involved in carbohydrate metabolism inside the organism. We propose that this enzyme is involved in either starch digestion or glycogen metabolism. 37 refs., 6 figs., 1 tab.

  14. AGI, a previously unreported D. melanogaster alpha-glucosidase: partial purification, characterization, and cytogenetic mapping.

    Science.gov (United States)

    Parker, G F; Roberts, D B

    1996-04-01

    Inbred Drosophila melanogaster stocks were surveyed for alpha-glucosidases with nondenaturing gel electrophoresis using a fluorogenic substrate to stain the gels. The glucosidase most active under these conditions is polymorphic. We established that the polymorphism is genetic in origin and that the glucosidase was not likely to be a previously characterized enzyme. The gene encoding the enzyme was mapped cytogenetically to 33 A1-2- 33A8-B1, confirming that this is an enzyme not yet reported in D. melanogaster. The enzyme was partially purified by elution from nondenaturing gels, which enabled us to establish that it has optimal activity at pH 6 and interacts most strongly with alpha-1-4 glucosides. A developmental and tissue survey suggested that this enzyme could have a purely digestive role or be involved in carbohydrate metabolism inside the organism. We propose that this enzyme is involved in either starch digestion or glycogen metabolism.

  15. Synergy of CO/[CII]/Ly$\\alpha$ Line Intensity Mapping with the SKA

    CERN Document Server

    Chang, Tzu-Ching; Santos, Mario; Silva, Marta; Aguirre, James; Doré, Olivier; Pritchard, Jonathan

    2015-01-01

    We present the science enabled by cross-correlations of the SKA1-LOW 21-cm EoR surveys with other line mapping programs. In particular, we identify and investigate potential synergies with planned programs, such as the line intensity mapping of redshifted CO rotational lines, [CII] and Ly-$\\alpha$ emissions during reionization. We briefly describe how these tracers of the star-formation rate at $z \\sim 8$ can be modeled jointly before forecasting their auto- and cross-power spectra measurements with the nominal 21cm EoR survey. The use of multiple line tracers would be invaluable to validate and enrich our understanding of the EoR.

  16. Probing high-redshift galaxies with Ly$\\alpha$ intensity mapping

    CERN Document Server

    Comaschi, P

    2015-01-01

    We present a study of the cosmological Ly$\\alpha$ emission signal at $z > 4$. Our goal is to predict the power spectrum of the spatial fluctuations that could be observed by an intensity mapping survey. The model uses the latest data from the HST legacy fields and the abundance matching technique to associate UV emission and dust properties with the halos, computing the emission from the interstellar medium (ISM) of galaxies and the intergalactic medium (IGM), including the effects of reionization, self-consistently. The Ly$\\alpha$ intensity from the diffuse IGM emission is 1.3 (2.0) times more intense than the ISM emission at $z = 4(7)$; both components are fair tracers of the star-forming galaxy distribution. However the power spectrum is dominated by ISM emission on small scales ($k > 0.01 h{\\rm Mpc}^{-1}$) with shot noise being significant only above $k = 1 h{\\rm Mpc}^{-1}$. At very lange scales ($k < 0.01h{\\rm Mpc}^{-1}$) diffuse IGM emission becomes important. The comoving Ly$\\alpha$ luminosity densi...

  17. Recent Mapping and Sampling on Chukchi Borderland and the Alpha/Mendeleev Ridge Complex

    Science.gov (United States)

    Mayer, L. A.; Brumley, K.; Andronikov, A.; Chayes, D. N.; Armstrong, A. A.; Calder, B.; Hall, J. K.; Clyde, W. C.; Bothner, W. A.; Gardner, J. V.

    2008-12-01

    Since 2003, four cruises on the icebreaker USCG HEALY have collected high-resolution multibeam sonar mapping data in the Amerasia Basin in support of a potential submission by the U.S. for an extended continental shelf as defined under the United Nations Convention on Law of the Sea Article 76. The latest of these cruises (HEALY0805), completed in early Sept.of 2008, extended this mapping to the southern portions of the Alpha/Mendeleev Ridge complex, and supplemented the mapping with seven dredge stations, providing rare, direct sampling of both regions. While sparse in comparison to complete-coverage multibeam sonar surveys (due to the difficulties associated with operating in ice-covered waters), the new multibeam sonar data still provide an unprecedented new view of the tectonic, sedimentary, glacial and fluid- flow related processes in the Arctic Ocean. The Chukchi Borderland is characterized by shallow plateaus that often show evidence of interaction with icebergs and glaciers (scours and grooves) at depths as great as 900 m, as well as the presence of numerous gas/fluid expulsion features (pockmarks and acoustic wipe-out zones). The topographic highs associated with the Borderland are often bounded by very steep scarps including the eastern edge of Northwind Ridge (the Northwind Escarpment) which is a 600 km long NNE trending feature with an average slope of 10-15 degrees. Similar steep-sided ridges, separated by deep linear valleys also appear in mapped areas of the Alpha/Mendeleev Ridge complex. Some of these features have slopes as great at 60 degrees and thus are excellent targets for dredging. Our dredging of these slopes has returned a wide array of volcanic and sedimentary rock types, many of which appear to be representative of outcrops (rather than ice rafted material). A preliminary shipboard examination of these samples (they were just collected this morning - 3 September 2008 - a few days before the abstract is due) shows them to include mudstone

  18. The Lyman-beta forest as a cosmic thermometer

    CERN Document Server

    Iršič, Vid

    2014-01-01

    We present a comprehensive analysis of high resolution hydrodynamic simulations in terms of Lyman-alpha and Lyman-beta one dimensional flux power spectra ($P_{\\alpha\\alpha}$ and $P_{\\beta\\beta}$). In particular, we focus on the behaviour that the flux auto-power spectra and cross-power spectra ($P_{\\alpha\\beta}$) display when the intergalactic medium (IGM) thermal history is changed in a range of values that bracket a reference model, while cosmological parameters are kept fixed to best fit the cosmic microwave background data. We present empirical fits that describe at the sub-percent level the dependence of the power spectra on the thermal parameters. At the largest scales, the power spectra show a constant bias between each other that is set by the parameters describing the IGM thermal state. The cross-power spectrum has an oscillatory pattern and crosses zero at a scale which depends on $T_0$, the IGM temperature at the mean density, for reasonable values of the power-law index $\\gamma$ of the IGM tempera...

  19. Intensity mapping of H-alpha, H-beta, [OII] and [OIII] lines at z<5

    CERN Document Server

    Gong, Yan; Silva, Marta B; Zemcov, Michael; Feng, Chang; Santos, Mario G; Dore, Olivier; Chen, Xuelei

    2016-01-01

    Intensity mapping is now becoming a useful tool to study the large-scale structure of the universe through spatial variations in the integrated emission from galaxies and the intergalactic medium. We study intensity mapping of the H-alpha6563A, [OIII]5007A, [OII]3727A and H-beta4861A lines at 0.8Mapping Experiment), Ti...

  20. The evolution of neutral gas in damped Lyman α systems from the XQ-100 survey

    DEFF Research Database (Denmark)

    Sánchez-Ramírez, R.; Ellison, S. L.; Prochaska, J. X.

    2015-01-01

    We present a sample of 38 intervening Damped Lyman $\\alpha$ (DLA) systems identified towards 100 $z>3.5$ quasars, observed during the XQ-100 survey. The XQ-100 DLA sample is combined with major DLA surveys in the literature. The final combined sample consists of 742 DLAs over a redshift range app...

  1. Alpha-synuclein in familial Alzheimer disease: epitope mapping parallels dementia with Lewy bodies and Parkinson disease.

    Science.gov (United States)

    Lippa, C F; Schmidt, M L; Lee, V M; Trojanowski, J Q

    2001-11-01

    Alpha-synuclein is a major component of Lewy bodies (LBs) in Parkinson disease and dementia with LBs and of glial cytoplasmic inclusions in multiple system atrophy. However, epitope mapping for alpha-synuclein is distinctive in different neurodegenerative diseases. The reasons for this are poorly understood but may reflect fundamental differences in disease mechanisms. To investigate the alpha-synuclein epitope mapping properties of LBs in familial Alzheimer disease. We compared LBs in familial Alzheimer disease with those in synucleinopathies by probing 6 brains of persons with familial Alzheimer disease using a panel of antibodies to epitopes spanning the alpha-synuclein protein. Results were compared with data from brains of persons with Parkinson disease, dementia with LBs, and multiple system atrophy. The brains of persons with familial Alzheimer disease showed consistent staining of LBs with all antibodies, similar to Parkinson disease and dementia with LBs but different from alpha-synuclein aggregates that occurred in multiple system atrophy. These data suggest that the epitope profiles of alpha-synuclein in LBs are similar, regardless of whether the biological trigger is related to synuclein or a different genetic pathway. These findings support the hypothesis that the mechanism of alpha-synuclein aggregation is the same within cell types but distinctive between cell types.

  2. Aeronomy, a 20th Century emergent science: the role of solar Lyman series

    Directory of Open Access Journals (Sweden)

    G. Kockarts

    Full Text Available Aeronomy is, by definition, a multidisciplinary science which can be used to study the terrestrial atmosphere, as well as any planetary atmosphere and even the interplanetary space. It was officially recognized in 1954 by the International Union of Geodesy and Geophysics. The major objective of the present paper is to show how aeronomy developed since its infancy. The subject is so large that a guide-line has been chosen to see how aeronomy affects our atmospheric knowledge. This guideline is the solar Lyman alpha radiation which has different effects in the solar system. After a short description of the origins of aeronomy the first observations of this line are summarized since the beginning of the space age. Then the consequences of these observations are analyzed for the physics and chemistry of the neutral terrestrial atmosphere. New chemical processes had to be introduced, as well as new transport phenomena. Solar Lyman alpha also influences the structure of the Earth’s ionosphere, particularly the D-region. In the terrestrial exosphere, solar Lyman alpha scattered resonantly by atomic hydrogen is at present the only way to estimate this constituent in an almost collisionless medium. Since planetary atmospheres also contain atomic hydrogen, the Lyman alpha line has been used to deduce the abundance of this constituent. The same is true for the interplanetary space where Lyman alpha observations can be a good tool to determine the concentration. The last section of the paper presents a question which is intended to stimulate further research in aeronomy.

    Key words. Atmospheric composition and structure (middle atmosphere – composition and chemistry; thermosphere – composition and chemistry – history of geophysics (atmospheric sciences

  3. Indirect Evidence for Escaping Lyman Continuum Photons in Local Lyman Break Galaxy Analogs

    Science.gov (United States)

    Alexandroff, Rachael; Heckman, Timothy M.; Borthakur, Sanchayeeta; Overzier, Roderik

    2015-01-01

    A population of early star-forming galaxies is the leading candidate for the re-ionization of the universe. It is still unclear, however, what conditions and physical processes would enable a significant fraction of the ionizing photons to escape from these gas-rich galaxies. In addition, studies of high redshift galaxies have yet to uncover a large sample of galaxies with the required high escape fraction of ionizing photons.We have uncovered a sample of local analogs to high-redshift, star-forming Lyman Break Galaxies (LBGs) called Lyman Break Analogs (LBAs) by matching the Sloan Digital Sky Survey (SDSS) and Galaxy Evolution Explorer (GALEX) catalogs. These galaxies are remarkably similar to LBGs in their properties-- morphology, size, UV luminosity, SFR, mass, velocity dispersion, metallicity and dust content. We obtained HST COS far-UV spectroscopy plus ancillary multi-waveband data of a sample of 22 LBAs to look for indirect evidence of escaping ionizing radiation (leakiness).We measure three parameters: (1) the residual intensity in the cores of saturated interstellar low-ionization absorption-lines, which indicates incomplete covering by that gas in the galaxy. (2) The relative amount of blue-shifted Lyman alpha line emission, which can indicate the existence of holes in the neutral hydrogen on the front-side of the galaxy outflow, and (3) the relative weakness of the [SII] optical emission lines that trace matter-bounded HII regions. We find all three diagnostics agree well with one another. Finally, we find the strongest correlation between these leakiness indicators and both the compactness of the galactic star-forming region (size and star formation rate/area) and the speed of the galactic outflow. This suggests that extreme feedback- a high intensity of ionizing radiation and strong pressure from both radiation and a hot galactic wind- combines to create significant holes in the neutral gas. These results not only shed new light on the physical

  4. Mapping of HNF4alpha target genes in intestinal epithelial cells

    DEFF Research Database (Denmark)

    Boyd, Mette; Bressendorff, Simon; Moller, Jette

    2009-01-01

    in the human intestinal epithelial cells in order to elucidate the role of HNF4alpha in the intestinal differentiation progress. METHODS: We have performed a ChIP-chip analysis of the human intestinal cell line Caco-2 in order to make a genome-wide identification of HNF4alpha binding to promoter regions......ABSTRACT: BACKGROUND: The role of HNF4alpha has been extensively studied in hepatocytes and pancreatic beta-cells, and HNF4alpha is also regarded as key regulator of intestinal epithelial cell differentiation as well. The aim of the present work is to identify novel HNF4alpha target genes......), and the tight junction protein cingulin (CGN) promoters verified that these genes are bound by HNF4alpha in Caco2 cells and for the Cdx-2 and trehalase promoters the HNF4alpha binding was verified in mouse small intestine epithelium. CONCLUSION: The HNF4alpha regulation of the Cdx-2 promoter unravels...

  5. Genetic mapping of the alpha-galactosidase MEL gene family on right and left telomeres of Saccharomyces cerevisiae.

    Science.gov (United States)

    Naumov, G I; Naumova, E S; Louis, E J

    1995-04-30

    The alpha-galactosidase MEL2-MEL10 genes have been genetically mapped to right and left telomere regions of the following chromosomes of Saccharomyces cerevisiae: MEL2 at VII L, MEL3 at XVI L, MEL4 at XI L, MEL5 at IV L, MEL6 at XIII R, MEL7 at VI R, MEL8 at XV R, MEL9 at X R and MEL10 at XII R. A set of tester strains with URA3 inserted into individual telomeres and no MEL genes was used for mapping.

  6. Synergetic fMRI-EEG brain mapping in alpha-rhythm voluntary control mode.

    Science.gov (United States)

    Shtark, M B; Verevkin, E G; Kozlova, L I; Mazhirina, K G; Pokrovskii, M A; Petrovskii, E D; Savelov, A A; Starostin, A S; Yarosh, S V

    2015-03-01

    For the first time in neurobiology-related issues, the synergistic spatial dynamics of EEG and fMRI (BOLD phenomenon) was studied during cognitive alpha biofeedback training in the operant conditioning mode (acoustic reinforcement of alpha-rhythm development and stability). Significant changes in alpha-rhythm intensity were found in T6 electrode area (Brodmann area 37). Brodmann areas related to solving alpha-training tasks and maximally involved in the formation of new neuronal network were middle and superior temporal gyri (areas 21, 22, and 37), fusiform gyrus, inferior frontal gyrus (areas 4, 6, and 46), anterior cingulate gyrus (areas 23 and 24), cuneus, and precuneus (area 7). Wide involvement of Brodmann areas is determined by psychological architecture of alpha-rhythm generating system control that includes complex cognitive activities: decision making, retrieval of long-term memory, evaluation of the reward and control efficiency during alpha-EEG biofeedback.

  7. Damped Lyman-α Systems

    Science.gov (United States)

    Petitjean, P.; Ledoux, C.

    Recently, Prochaska & Wolfe (1997) have used Keck spectra of 17 DLA absorbers to investigate the kinematics of the neutral gas using unsaturated low excitation transitions such as Si iiλ 1808. They show that the absorption profiles are inconsistent with models of galactic haloes with random motions, spherically infalling gas and slowly rotating hot disks. The CDM model (Kauffmann 1996) is rejected as it produces disks with rotation velocities too small to account for the large observed velocity broadening of the absorption lines. Models of thick disks (h ~0.3 R, where h is the vertical scale and R the radius) with large rotational velocity (v 225kms-1) can reproduce the data. By combining new data on five damped systems with information gathered in the literature, we study the kinematics of the low and high-ionization phases in a sample of 26 damped Lyman-α systems in the redshift range 1.17 - 4.38. We show that the broader the line the more asymmetric, as expected in case rotation dominates the line broadening. However this correlation does not hold for velocities larger than 150 km/s indicating that evidence for rotational motions if any is restricted to velocity broadenings Δ V 200kms-1 are peculiar with kinematics consistent with random motions. They show sub-systems as those expected if the objects are in the process of merging.

  8. Mapping of the spectral density function of a C alpha-H alpha bond vector from NMR relaxation rates of a 13C-labelled alpha-carbon in motilin.

    Science.gov (United States)

    Allard, P; Jarvet, J; Ehrenberg, A; Gräslund, A

    1995-02-01

    The peptide hormone motilin was synthesised with a 13C-enriched alpha-carbon in the leucine at position 10. In aqueous solution, six different relaxation rates were measured for the 13C alpha-H alpha fragment as a function of temperature and with and without the addition of 30% (v/v) of the cosolvent d2-1,1,1,3,3,3-hexafluoro-2-propanol (HFP). The relaxation rates were analysed employing the spectral density mapping technique introduced by Peng and Wagner [(1992) J. Magn. Reson., 98, 308-332] and using the model-free approach by Lipari and Szabo [(1982) J. Am. Chem. Soc., 104, 4546-4570]. The fit to various models of dynamics was also considered. Different procedures to evaluate the overall rotational correlation time were compared. A single exponential time correlation function was found to give a good fit to the measured spectral densities only for motilin in 30% (v/v) HFP at low temperatures, whereas at high temperatures in this solvent, and in D2O at all temperatures, none of the considered models gave an acceptable fit. A new empirical spectral density function was tested and found to accurately fit the experimental spectral density mapping points. The application of spectral density mapping based on NMR relaxation data for a specific 13C-1H vector is shown to be a highly useful method to study biomolecular dynamics. Advantages are high sensitivity, high precision and uniform sampling of the spectral density function over the frequency range.

  9. Synergistic effect of vasoactive intestinal peptides on TNF-alpha-induced IL-6 synthesis in osteoblasts: amplification of p44/p42 MAP kinase activation.

    Science.gov (United States)

    Natsume, Hideo; Tokuda, Haruhiko; Mizutani, Jun; Adachi, Seiji; Matsushima-Nishiwaki, Rie; Minamitani, Chiho; Kato, Kenji; Kozawa, Osamu; Otsuka, Takanobu

    2010-05-01

    We previously showed that tumor necrosis factor-alpha (TNF-alpha) stimulates synthesis of interleukin-6 (IL-6), a potent bone resorptive agent, via p44/p42 mitogen-activated protein (MAP) kinase and phosphatidylinositol 3-kinase/Akt in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the effect of vasoactive intestinal peptide (VIP) on TNF-alpha-induced IL-6 synthesis in these cells. VIP, which by itself slightly stimulated IL-6 synthesis, synergistically enhanced the TNF-alpha-induced IL-6 synthesis in MC3T3-E1 cells. The synergistic effect of VIP on the TNF-alpha-induced IL-6 synthesis was concentration-dependent in the range between 1 and 70 nM. We previously reported that VIP stimulated cAMP production in MC3T3-E1 cells. Forskolin, a direct activator of adenylyl cyclase, or 8-bromoadenosine-3',5'-cyclic monophosphate (8bromo-cAMP), a plasma membrane-permeable cAMP analogue, markedly enhanced the TNF-alpha-induced IL-6 synthesis as well as VIP. VIP markedly up-regulated the TNF-alpha-induced p44/p42 MAP kinase phosphorylation. The Akt phosphorylation stimulated by TNF-alpha was only slightly affected by VIP. PD98059, a specific inhibitor of MEK1/2, significantly suppressed the enhancement of TNF-alpha-induced IL-6 synthesis by VIP. The synergistic effect of a combination of VIP and TNF-alpha on the phosphorylation of p44/p42 MAP kinase was diminished by H-89, an inhibitor of cAMP-dependent protein kinase. These results strongly suggest that VIP synergistically enhances TNF-alpha-stimulated IL-6 synthesis via up-regulating p44/p42 MAP kinase through the adenylyl cyclase-cAMP system in osteoblasts.

  10. Paralogous sm22alpha (Tagln) genes map to mouse chromosomes 1 and 9: further evidence for a paralogous relationship.

    Science.gov (United States)

    Stanier, P; Abu-Hayyeh, S; Murdoch, J N; Eddleston, J; Copp, A J

    1998-07-01

    SM22alpha (TAGLN) is one of the earliest markers of differentiated smooth muscle, being expressed exclusively in the smooth muscle cells of adult tissues and transiently in embryonic skeletal and cardiac tissues. We have identified and mapped the mouse Tagln gene and a closely related gene, Sm22alpha homolog (Tagln2). The chromosomal localization for Tagln was identified by linkage analysis to distal mouse chromosome 9 between D9Mit154 and D9Mit330, closely linked to the anchor locus D9Nds10. The localization of Tagln2 was also determined and was found to map between Fcgr2 and D1Mit149 on distal mouse chromosome 1. This localization is homologous to a region of human 1q21-q25 to which an EST representing human TAGLN2 was previously mapped. The two regions, distal mouse chromosome 1 and proximal mouse chromosome 9, and the human regions with conserved synteny (1q21-q25 and 11q22-qter) are believed to be paralogous, reflecting either conserved remnants of duplicated chromosomes or segments of chromosomes during vertebrate evolution. Copyright 1998 Academic Press.

  11. Unique Astrophysics in the Lyman Ultraviolet

    CERN Document Server

    Tumlinson, Jason; Kriss, Gerard; France, Kevin; McCandliss, Stephan; Sembach, Ken; Fox, Andrew; Tripp, Todd; Jenkins, Edward; Beasley, Matthew; Danforth, Charles; Shull, Michael; Stocke, John; Lehner, Nicolas; Howk, Christopher; Froning, Cynthia; Green, James; Oliveira, Cristina; Fullerton, Alex; Blair, Bill; Kruk, Jeff; Sonneborn, George; Penton, Steven; Wakker, Bart; Prochaska, Xavier; Vallerga, John; Scowen, Paul

    2012-01-01

    There is unique and groundbreaking science to be done with a new generation of UV spectrographs that cover wavelengths in the "Lyman Ultraviolet" (LUV; 912 - 1216 Ang). There is no astrophysical basis for truncating spectroscopic wavelength coverage anywhere between the atmospheric cutoff (3100 Ang) and the Lyman limit (912 Ang); the usual reasons this happens are all technical. The unique science available in the LUV includes critical problems in astrophysics ranging from the habitability of exoplanets to the reionization of the IGM. Crucially, the local Universe (z <= 0.1) is entirely closed to many key physical diagnostics without access to the LUV. These compelling scientific problems require overcoming these technical barriers so that future UV spectrographs can extend coverage to the Lyman limit at 912 Ang.

  12. Mapping of alpha-neo-endorphin- and neurokinin B-immunoreactivity in the human brainstem.

    Science.gov (United States)

    Duque, Ewing; Mangas, Arturo; Salinas, Pablo; Díaz-Cabiale, Zaida; Narváez, José Angel; Coveñas, Rafael

    2013-01-01

    We have studied the distribution of alpha-neo-endorphin- or neurokinin B-immunoreactive fibres and cell bodies in the adult human brainstem with no prior history of neurological or psychiatric disease. A low density of alpha-neo-endorphin-immunoreactive cell bodies was only observed in the medullary central gray matter and in the spinal trigeminal nucleus (gelatinosa part). Alpha-neo-endorphin-immunoreactive fibres were moderately distributed throughout the human brainstem. A high density of alpha-neo-endorphin-immunoreactive fibres was found only in the solitary nucleus (caudal part), in the spinal trigeminal nucleus (caudal part), and in the gelatinosa part of the latter nucleus. Neurokinin B-immunoreactive cell bodies (low density) were found in the periventricular central gray matter, the reticular formation of the pons and in the superior colliculus. The distribution of the neurokinin-immunoreactive fibres was restricted. In general, for both neuropeptides the density of the immunoreactive fibres was low. In the human brainstem, the proenkephalin system was more widely distributed than the prodynorphin system, and the preprotachykinin A system (neurokinin A) was more widely distributed than the preprotachykinin B system (neurokinin B).

  13. An extreme [OIII] emitter at $z=3.2$: a low metallicity Lyman continuum source

    CERN Document Server

    de Barros, S; Amorín, R; Castellano, M; Siana, B; Grazian, A; Suh, H; Balestra, I; Vignali, C; Verhamme, A; Zamorani, G; Mignoli, M; Hasinger, G; Comastri, A; Pentericci, L; Pérez-Montero, E; Fontana, A; Giavalisco, M; Gilli, R

    2016-01-01

    [Abridged] We investigate the physical properties of a Lyman continuum emitter candidate at $z=3.212$ with photometric coverage from $U$ to MIPS 24$\\mu$m band and VIMOS/VLT and MOSFIRE/Keck spectroscopy. Investigation of the UV spectrum confirms a direct spectroscopic detection of the Lyman continuum emission with $S/N>5$. Non-zero Ly$\\alpha$ flux at the systemic redshift and high Lyman-$\\alpha$ escape fraction suggest a low HI column density. The weak C and Si low-ionization absorption lines are also consistent with a low covering fraction along the line of sight. The [OIII]$\\lambda\\lambda4959,5007+\\mathrm{H}\\beta$ equivalent width is one of the largest reported for a galaxy at $z>3$ ($\\mathrm{EW}([\\mathrm{OIII}]\\lambda\\lambda4959,5007+\\mathrm{H}\\beta) \\simeq 1600\\AA$, rest-frame) and the NIR spectrum shows that this is mainly due to an extremely strong [OIII] emission. The large observed [OIII]/[OII] ratio ($>10$) and high ionization parameter are consistent with prediction from photoionization models in ca...

  14. Detection of Lyman continuum absorption in the BL Lacertae object PKS 0735+178

    Science.gov (United States)

    Bregman, J. N.; Glassgold, A. E.; Huggins, P. J.

    1981-01-01

    The detection of the Lyman edge in the BL Lac object PKS 0735+178 at the absorption red shift determined by optical measurements leads to a lower limit for the column density of atomic hydrogen, N(H I) not less than 4(17)/sq cm. The Lyman-alpha absorption line appears to have been detected, but only an approximate upper limit can be obtained from the data, of the order of 2(19)/sq cm. This amount of atomic hydrogen is less than that for a line of sight through the disk of a normal spiral galaxy. It is suggested that the absorbing material exists either in the halo of a galaxy or in the tenuous, extended, gaseous disk of a galaxy.

  15. Lyman-alpha Cooling Emission from Galaxy Formation

    CERN Document Server

    Faucher-Giguere, C -A; Dijkstra, M; Hernquist, L; Zaldarriaga, M

    2010-01-01

    Recent studies have shown that galaxies accrete most of their baryons via the cold mode, from streams with temperatures T~10^4-10^5 K. At these temperatures, the streams should radiate primarily in Lya and have therefore been proposed as a model to power the Lya blobs and other high-redshift Lya sources. We introduce a new Lya radiative transfer code, aRT, and apply it to cosmological hydrodynamical simulations. We address physical and numerical issues that are critical to making accurate predictions for the cooling luminosity, but that have been mostly neglected or treated simplistically so far. We highlight the importance of self-shielding and of properly treating sub-resolution models in simulations. Most existing simulations do not self-consistently incorporate these effects, which can lead to order-of-magnitude errors in the predicted cooling luminosity. Using a combination of post-processing ionizing radiative transfer and re-simulation techniques, we develop an approximation to the consistent evolution...

  16. Exploring 21cm-Lyman Alpha Emitter Synergies for SKA

    Science.gov (United States)

    Hutter, Anne; Dayal, Pratika; Müller, Volker; Trott, Cathryn M.

    2017-02-01

    We study the signatures of reionization and ionizing properties of early galaxies in the cross-correlations between the 21 cm emission from the spin-flip transition of neutral hydrogen (H i) and the underlying galaxy population. In particular, we focus on a sub-population of galaxies visible as Lyα Emitters (LAEs). With both observables simultaneously derived from a z≃ 6.6 hydrodynamical simulation (GADGET-2) snapshot post-processed with a radiative transfer code (pCRASH) and a dust model, we perform a parameter study and aim to constrain both the average intergalactic medium (IGM) ionization state (1- ) and the reionization topology (outside-in versus inside-out). We find that, in our model, LAEs occupy the densest and most-ionized regions resulting in a very strong anti-correlation between the LAEs and the 21 cm emission. A 1000 hr Square Kilometer Array (SKA)-LOW1—Subaru Hyper Suprime-Cam experiment can provide constraints on , allowing us to distinguish between IGM ionization levels of 50%, 25%, 10%, and fully ionized at scales r≲ 10 comoving Mpc (assuming foreground avoidance for SKA). Our results support the inside-out reionization scenario where the densest knots (under-dense voids) are ionized first (last) for ≳ 0.1. Further, 1000 hr SKA-LOW1 observations should be able to confirm the inside-out scenario by detecting a lower 21 cm brightness temperature (by about 2–10 mK) in the densest regions (≳2 arcmin scales) hosting LAEs, compared to lower-density regions devoid of them.

  17. Lyman-alpha Damping Wing Constraints on Inhomogeneous Reionization

    CERN Document Server

    Mesinger, Andrei

    2007-01-01

    One well-known way to constrain the hydrogen neutral fraction, x_H, of the high-redshift intergalactic medium (IGM) is through the shape of the red damping wing of the Lya absorption line. We examine this method's effectiveness in light of recent models showing that the IGM neutral fraction is highly inhomogeneous on large scales during reionization. Using both analytic models and "semi-numeric" simulations, we show that the "picket-fence" absorption typical in reionization models introduces both scatter and a systematic bias to the measurement of x_H. In particular, we show that simple fits to the damping wing tend to overestimate the true neutral fraction in a partially ionized universe, with a fractional error of ~ 30% near the middle of reionization. This bias is generic to any inhomogeneous model. However, the bias is reduced and can even underestimate x_H if the observational sample only probes a subset of the entire halo population, such as quasars with large HII regions. We also find that the damping ...

  18. Mutagenesis of p38alpha MAP Kinase Establishes Key Roles of Phe169 in Function and Structural Dynamics and Reveals a Novel DFG-OUT State

    Energy Technology Data Exchange (ETDEWEB)

    Bukhtiyarova,M.; Karpusas, M.; Northrup, K.; Namboodiri, H.; Springman, E.

    2007-01-01

    In order to study the role of Phe169 in p38{alpha} MAP kinase structure and function, wild-type p38{alpha} and five p38{alpha} DFG motif mutants were examined in vitro for phosphorylation by MKK6, kinase activity toward ATF2 substrate, thermal stability, and X-ray crystal structure. All six p38{alpha} variants were efficiently phosphorylated by MKK6. However, only one activated p38{alpha} mutant (F169Y) possessed measurable kinase activity (1% compared to wild-type). The loss of kinase activity among the DFG mutants may result from an inability to correctly position Asp168 in the activated form of p38{alpha}. Two mutations significantly increased the thermal stability of p38{alpha} (F169A {Delta}T{sub m} = 1.3 {sup o}C and D168G {Delta}T{sub m} = 3.8 {sup o}C), and two mutations significantly decreased the stability of p38{alpha} (F169R {Delta}T{sub m} = -3.2 {sup o}C and F169G {Delta}T{sub m} = -4.7 {sup o}C). Interestingly, X-ray crystal structures of two thermally destabilized p38{alpha}-F169R and p38{alpha}-F169G mutants revealed a DFG-OUT conformation in the absence of an inhibitor molecule. This DFG-OUT conformation, termed {alpha}-DFG-OUT, is different from the ones previously identified in p38{alpha} crystal structures with bound inhibitors and postulated from high-temperature molecular dynamics simulations. Taken together, these results indicate that Phe169 is optimized for p38{alpha} functional activity and structural dynamics, rather than for structural stability. The {alpha}-DFG-OUT conformation observed for p38{alpha}-F169R and p38{alpha}-F169G may represent a naturally occurring intermediate state of p38{alpha} that provides access for binding of allosteric inhibitors. A model of the local forces driving the DFG IN-OUT transition in p38{alpha} is proposed.

  19. Io's SO2 Atmosphere Viewed in Silhouette by Jupiter Lyman

    Science.gov (United States)

    Retherford, Kurt D.; Roth, Lorenz; Feaga, Lori M.; Becker, Tracy M.; Tsang, Constantine; Jessup, Kandis-Lea; Grava, Cesare

    2016-10-01

    We report a new technique for mapping Io's SO2 vapor distribution. Hubble's Space Telescope Imaging Spectrograph (STIS) instrument observed Io during four Jupiter transit events to obtain medium resolution far-UV spectral images near the Lyman-α wavelength of 121.6 nm. Jupiter's bright Lyman-α dayglow provides a background light source for opacity measurements, much like during a stellar occultation or transiting exoplanet event. Peaks in the photoabsorption cross-sections for sulfur dioxide occur near 122 nm, with resulting absorptions raising the altitude where a tangential line of sight opacity of tau=1 is detected up to resolvable distances above the disk. This method of measuring column densities along lines of sight above the limb complements Lyman-α reflectance imaging and other methods for measuring Io's SO2 gas. For example, interpretation of Io's surface reflected components at far-UV wavelengths is complicated by SO2 frost features being correlated with regions of known volcanic outgassing activity, while Jupiter's Lyman-α dayglow provides a more spatially uniform background light source. Initial examination of these near-terminator limb observations with STIS confirms the findings from previous Lyman-α disk reflectance imaging using STIS's G140L mode (e.g., Feldman et al., GRL, 2000; Feaga et al. 2009) that Io's polar SO2 density is roughly an order of magnitude lower than found at the equator. As Strobel & Wolven (2001) described it, Io appears to wear its dayside atmosphere as "a belt" around the equator. We describe detailed simulations, now underway, that incorporate the STIS point spread function and consideration of additional attenuation by atmospheric hydrogen atoms, which are produced by charge exchange reactions between magnetospheric protons and Io's atmosphere.

  20. Amide-based inhibitors of p38alpha MAP kinase. Part 2: design, synthesis and SAR of potent N-pyrimidyl amides.

    Science.gov (United States)

    Tester, Richland; Tan, Xuefei; Luedtke, Gregory R; Nashashibi, Imad; Schinzel, Kurt; Liang, Weiling; Jung, Joon; Dugar, Sundeep; Liclican, Albert; Tabora, Jocelyn; Levy, Daniel E; Do, Steven

    2010-04-15

    Optimization of a tri-substituted N-pyridyl amide led to the discovery of a new class of potent N-pyrimidyl amide based p38alpha MAP kinase inhibitors. Initial SAR studies led to the identification of 5-dihydrofuran as an optimal hydrophobic group. Additional side chain modifications resulted in the introduction of hydrogen bond interactions. Through extensive SAR studies, analogs bearing free amino groups and alternatives to the parent (S)-alpha-methyl benzyl moiety were identified. These compounds exhibited improved cellular activities and maintained balance between p38alpha and CYP3A4 inhibition.

  1. Mapping of the {alpha}{sub 4} subunit gene (GABRA4) to human chromosome 4 defines an {alpha}{sub 2}-{alpha}{sub 4}-{beta}{sub 1}-{gamma}{sub 1} gene cluster: Further evidence that modern GABA{sub a} receptor gene clusters are derived from an ancestral cluster

    Energy Technology Data Exchange (ETDEWEB)

    McLean, P.J.; Farb, D.H.; Russek, S.J. [Boston Univ. School of Medicine, MA (United States)] [and others

    1995-04-10

    We demonstrated previously that an {alpha}{sub 1}-{beta}{sub 2}-{gamma}{sub 2} gene cluster of the {gamma}-aminobutyric acid (GABA{sub A}) receptor is located on human chromosome 5q34-q35 and that an ancestral {alpha}-{beta}-{gamma} gene cluster probably spawned clusters on chromosomes 4, 5, and 15. Here, we report that the {alpha}{sub 4} gene (GABRA4) maps to human chromosome 4p14-q12, defining a cluster comprising the {alpha}{sub 2}, {alpha}{sub 4}, {beta}{sub 1}, and {gamma}{sub 1} genes. The existence of an {alpha}{sub 2}-{alpha}{sub 4}-{beta}{sub 1}-{gamma}{sub 2} cluster on chromosome 4 and an {alpha}{sub 1}-{alpha}{sub 6}-{beta}{sub 2}-{gamma}{sub 2} cluster on chromosome 5 provides further evidence that the number of ancestral GABA{sub A} receptor subunit genes has been expanded by duplication within an ancestral gene cluster. Moreover, if duplication of the {alpha} gene occurred before duplication of the ancestral gene cluster, then a heretofore undiscovered subtype of a subunit should be located on human chromosome 15q11-q13 within an {alpha}{sub 5}-{alpha}{sub x}-{beta}{sub 3}-{gamma}{sub 3} gene cluster at the locus for Angelman and Prader-Willi syndromes. 34 refs., 6 figs., 1 tab.

  2. Lyman Break Galaxies in the NGST Era

    CERN Document Server

    Ferguson, H C; Papovich, C; Ferguson, Henry C.; Dickinson, Mark; Papovich, Casey

    2002-01-01

    With SIRTF and NGST in the offing, it is interesting to examine what the stellar populations of z~3 galaxies models imply for the existence and nature of Lyman-break galaxies at higher redshift. To this end, we ``turn back the clock'' on the stellar population models that have been fit to optical and infrared data of Lyman-break galaxies at z~3. The generally young ages (typically 10^8 +- 0.5 yr) of these galaxies imply that their stars were not present much beyond z=4. For smooth star-formation histories SFR(t) and Salpeter IMFs, the ionizing radiation from early star-formation in these galaxies would be insufficient to reionize the intergalactic medium at z~6, and the luminosity density at z~4 would be significantly lower than observed. We examine possible ways to increase the global star-formation rate at higher redshift without violating the stellar-population constraints at z~3.

  3. Lyman Spitzer: Life, Times, and Science

    Indian Academy of Sciences (India)

    2016-11-01

    Lyman Spitzer was one of the major figures of twentieth centurytheoretical astrophysics. Over more than fifty years,he kept up sustained research of his own, on problems concerningthe interstellar medium, star formation, and galaxies.In addition he was a major influence on observationalprogrammes, and created a thriving school of theoretical astrophysicsat Princeton University along with a strong plasmaphysics programme. This article brings out his contributions,placing them in context.

  4. Lyman edges in AGN accretion discs

    Energy Technology Data Exchange (ETDEWEB)

    Czerny, B. (Copernicus Astronomical Center, Warsaw (Poland)); Pojmanski, G. (Warsaw Univ. (Poland). Obserwatorium Astronomiczne)

    1990-07-01

    We show that the basic difference in the two principal approaches to predictions of the Lyman edge in an accretion disc lies in the implicit assumption about the density of the radiating gas. Independent from the details, models predict a broad range of the edge sizes, both in absorption and in emission. Observed spectra do not exhibit any strong feature at 912 A but may still be consistent with an accretion disc mechanism if more advanced theory is developed. (author).

  5. Quantifying Distributions of Lyman Continuum Escape Fraction

    CERN Document Server

    Cen, Renyue

    2015-01-01

    Simulations have indicated that most of the escaped Lyman continuum photons escape through a minority of solid angles with near complete transparency, with the remaining majority of the solid angles largely opaque, resulting in a very broad and skewed probability distribution function (PDF) of the escape fraction when viewed at different angles. Thus, the escape fraction of Lyman continuum photons of a galaxy observed along a line of sight merely represents the properties of the interstellar medium along that line of sight, which may be an ill-representation of true escape fraction of the galaxy averaged over its full sky. Here we study how Lyman continuum photons escape from galaxies at $z=4-6$, utilizing high-resolution large-scale cosmological radiation-hydrodynamic simulations. We compute the PDF of the mean escape fraction ($\\left$) averaged over mock observational samples, as a function of the sample size, compared to the true mean (had you an infinite sample size). We find that, when the sample size is...

  6. A Low Upper Limit to the Lyman Continuum Emission of two galaxies at z 3

    CERN Document Server

    Giallongo, E; D'Odorico, S; Fontana, A

    2002-01-01

    Long exposure, long-slit spectra have been obtained in the UV/optical bands for two galaxies at z=2.96 and z=3.32 to investigate the fraction of ionizing UV photons escaping from high redshifts galaxies. The two targets are among the brightest galaxies discovered by Steidel and collaborators and they have different properties in terms of Lyman-alpha emission and dust reddening. No significant Lyman continuum emission has been detected. The noise level in the spectra implies an upper limit of f_{rel,esc}\\equiv 3 f(900)/f(1500)< 16% for the relative escape fraction of ionizing photons, after correction for absorption by the intervening intergalactic medium. This upper limit is 4 times lower than the previous detection derived from a composite spectrum of 29 Lyman break galaxies at z 3.4. If this value is typical of the escape fraction of the z 3 galaxies, and is added to the expected contribution of the QSO population, the derived UV background is in good agreement with the one derived by the proximity effec...

  7. Cloning and comparative mapping of a human chromosome 4-specific alpha satellite DNA sequence.

    Science.gov (United States)

    D'Aiuto, L; Antonacci, R; Marzella, R; Archidiacono, N; Rocchi, M

    1993-11-01

    We have isolated and characterized two human alphoid DNA clones: p4n1/4 and pZ4.1. Clone p4n1/4 identifies specifically the centromeric region of chromosome 4; pZ4.1 recognizes a subset of alphoid DNA shared by chromosomes 4 and 9. The specificity was determined using fluorescence in situ hybridization experiments on metaphase spreads and Southern blotting analysis of human-hamster somatic cell hybrids. The genomic organization of both subsets was also investigated. Comparative mapping on chimpanzee and gorilla chromosomes was performed. p4n1/4 hybridizes to chimpanzee chromosomes 11 and 13, homologs of human chromosomes 9 and 2q, respectively. On gorilla metaphase spreads, p4n1/4 hybridizes exclusively to the centromeric region of chromosome 19, partially homologous to human chromosome 17. No hybridization signal was detected on chromosome 3 of both chimpanzee and gorilla, in both species homolog of human chromosome 4. Identical comparative mapping results were obtained using pZ4.1 probe, although the latter recognizes an alphoid subset distinct from the one recognized by p4n1/4. The implications of these results in the evolution of centromeric regions of primate chromosomes are discussed.

  8. Cloning and comparative mapping of a human chromosome 4-specific alpha satellite DNA sequence

    Energy Technology Data Exchange (ETDEWEB)

    D' Aiuto, L.; Marzella, R.; Archidiacono, N.; Rocchi, M. (Universita di Bari (Italy)); Antonacci, R. (Instituto Anatomia Umana Normale, Modena (Italy))

    1993-11-01

    The authors have isolated and characterized two human alphoid DNA clones: p4n1/4 and pZ4.1. Clone p4n1/4 identifies specifically the centromeric region of chromosome 4; pZ4.1 recognizes a subset of alphoid DNA shared by chromosomes 4 and 9. The specificity was determined using fluorescence in situ hybridization experiments on metaphase spreads and Southern blotting analysis of human-hamster somatic cell hybrids. The genomic organization of both subsets was also investigated. Comparative mapping on chimpanzee and gorilla chromosomes was performed. p4n1/4 hybridizes to chimpanzee chromosomes 11 and 13, homologs of human chromosomes 9 and 2q, respectively. On gorilla metaphase spreads, p4n1/4 hybridizes exclusively to the centromeric region of chromosome 19, partially homologous to human chromosome 17. No hybridization signal was detected on chromosome 3 of both chimpanzee and gorilla, in both species homolog of human chromosome 4. Identical comparative mapping results were obtained using pZ4.1 probe, although the latter recognizes an alphoid subset distinct from the one recognized by p4n1/4. The implications of these results in the evolution of centromeric regions of primate chromosomes are discussed. 33 refs., 4 figs.

  9. The orphan nuclear receptor ROR{alpha} (RORA) maps to a conserved region of homology on human chromosome 15q21-q22 and mouse chromosome 9

    Energy Technology Data Exchange (ETDEWEB)

    Giguere, V. [McGill Univ., Montreal (Canada); Beatty, B.; Squire, J. [Hospital for Sick Children, Toronto (Canada)] [and others

    1995-08-10

    ROR{alpha} is a novel member of the steroid/thyroid/retinoid receptor superfamily with unique DNA-binding properties. We have mapped the RORA gene by fluorescence in situ hybridization to human chromosome 15q21-q22. To map the mouse Rora gene, a partial mouse cDNA clone was isolated from brain. Using interspecific backcross analysis, we have mapped the Rora gene to mouse chromosome 9. This places the human RORA gene in the proximity of the PML gene, which is involved in a reciprocal chromosomal translocation t(15:17) with the RARA gene in patients with acute promyelocytic leukemia. 13 refs., 2 figs.

  10. Isolation and comparative mapping of a human chromosome 20-specific alpha-satellite DNA clone.

    Science.gov (United States)

    Baldini, A; Archidiacono, N; Carbone, R; Bolino, A; Shridhar, V; Miller, O J; Miller, D A; Ward, D C; Rocchi, M

    1992-01-01

    We have isolated and characterized a human genomic DNA clone (PZ20, locus D20Z2) that identifies, under high-stringency hybridization conditions, an alphoid DNA subset specific for chromosome 20. The specificity was determined using fluorescence in situ hybridization. Sequence analysis confirmed our previously reported data on the great similarity between the chromosome 20 and chromosome 2 alphoid subsets. Comparative mapping of pZ20 on chimpanzee and gorilla chromosomes, also performed under high-stringency conditions, indicates that the alphoid subset has ancestral sequences on chimpanzee chromosome 11 and gorilla chromosome 19. However, no hybridization was observed to chromosomes 21 in the great apes, the homolog of human chromosome 20.

  11. Lyman continuum galaxies and the escape fraction of Lyman break galaxies

    CERN Document Server

    Cooke, Jeff; Garel, Thibault; Diaz, C Gonzalo

    2014-01-01

    Lyman break galaxies (LBGs) at z ~ 3-4 are targeted to measure the fraction of Lyman continuum (LyC) flux that escapes from high redshift galaxies. However, z ~ 3-4 LBGs are identified using the Lyman break technique which preferentially selects galaxies with little or no LyC. We re-examine the standard LBG selection criteria by performing spectrophotometry on composite spectra constructed from 794 U_nGR-selected z ~ 3 LBGs from the literature while adding LyC flux of varying strengths. The modified composite spectra accurately predict the range of redshifts, properties, and LyC flux of LBGs in the literature that have spectroscopic LyC measurements while predicting the existence of a significant fraction of galaxies outside the standard selection region. These galaxies, termed Lyman continuum galaxies (LCGs), are expected to have high levels of LyC flux and are estimated to have a number density ~30-50 percent that of the LBG population. We define R_obs(U_n) as the relative fraction of observed LyC flux, int...

  12. Lyman continuum leaking AGN in the SSA22 field

    CERN Document Server

    Micheva, Genoveva; Inoue, Akio K

    2016-01-01

    Subaru/SuprimeCam narrowband photometry of the SSA22 field reveals the presence of four Lyman continuum (LyC) candidates among a sample of 14 AGN. Two show offsets and likely have stellar LyC in nature or are foreground contaminants. The remaining two LyC candidates are Type I AGN. We argue that the average LyC escape fraction of high redshift quasars is not likely to be unity, as often assumed in the literature. From direct measurement we obtain the average LyC-to-UV flux density ratio and ionizing emissivity for a number of AGN classes and find it at least a factor of two lower than values obtained assuming f_esc = 1. Comparing to recent Ly{\\alpha} forest measurements, AGNs at redshift z\\sim3 make up at most \\sim20% and as little as 3% of the total ionizing budget. Our results suggest that AGNs are unlikely to dominate the ionization budget of the Universe at high redshifts.

  13. The Masses of Lyman Break Galaxies

    Science.gov (United States)

    Primack, Joel R.; Wechsler, Risa H.; Somerville, Rachel S.

    Data on galaxies at high redshift, identified by the Lyman-break photometric technique, can teach us about how galaxies form and evolve. The stellar masses and other properties of such Lyman break galaxies (LBGs) depend sensitively on the details of star formation. In this paper we consider three different star formation prescriptions, and use semi-analytic methods applied to the now-standard ΛCDM theory of hierarchical structure formation to show how these assumptions about star formation affect the predicted masses of the stars in these galaxies and the masses of the dark matter halos that host them. We find that, within the rather large uncertainties, recent estimates of the stellar masses of LBGs from multi-color photometry are consistent with the predictions of all three models. However, the estimated stellar masses are more consistent with the predictions of two of the models in which star formation is accelerated at high redshifts z ≳ 3, and of these models the one in which many of the LBGs are merger-driven starbursts is also more consistent with indications that many high redshift galaxies are gas rich. The clustering properties of LBGs have put some constraints on the masses of their host halos, but due to similarities in the halo occupation of the three models we consider and degeneracies between model parameters, current constraints are not yet sufficient to distinguish between realistic models.

  14. The Masses of Lyman Break Galaxies

    CERN Document Server

    Primack, Joel R; Somerville, R S; Primack, Joel R.; Wechsler, Risa H.; Somerville, Rachel S.

    2001-01-01

    Data on galaxies at high redshift, identified by the Lyman-break photometric technique, can teach us about how galaxies form and evolve. The stellar masses and other properties of such Lyman break galaxies (LBGs) depend sensitively on the details of star formation. In this paper we consider three different star formation prescriptions, and use semi-analytic methods applied to the now-standard $\\Lambda$CDM theory of hierarchical structure formation to show how these assumptions about star formation affect the predicted masses of the stars in these galaxies and the masses of the dark matter halos that host them. We find that, within the rather large uncertainties, recent estimates of the stellar masses of LBGs from multi-color photometry are consistent with the predictions of all three models. However, the estimated stellar masses are more consistent with the predictions of two of the models in which star formation is accelerated at high redshifts $z\\gsim3$, and of these models the one in which many of the LBGs...

  15. Lyman Continuum Emission from Galaxies at z~3.4

    CERN Document Server

    Steidel, C C; Adelberger, K L

    2000-01-01

    We report the detection of significant Lyman continuum flux in the composite spectrum of 29 Lyman break galaxies (LBGs) with redshifts = 3.40+/-0.09. After correction for opacity due to intervening absorption using a new composite QSO spectrum evaluated at the same redshift, the ratio of emergent flux density at 1500 \\AA in the rest frame to that in the Lyman continuum is L(1500)/L(900) = 4.6 +/- 1.0. If the relative intensity of the inferred escaping Lyman continuum radiation is typical of LBGs at z ~ 3 (the galaxies in this sample are drawn from the bluest quartile of LBG spectral energy distributions due to known selection effects), then observed LBGs produce about 5 times more H-ionizing photons per unit co-moving volume than QSOs at z ~ 3. The associated contribution to the metagalactic ionizing radiation field is J_{\

  16. Stellar Mass Function of Lyman Break Galaxies: Theoretical Perspective

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-Liang; HUANG Yong-Qing; LIU Nian-Hua; LAI Zhen-Quan; SHU Cheng-Gang

    2006-01-01

    @@ Adopting the observational distributions of star formation rates and half-light radii of Lyman break galaxies (LBGs) in the rest frame UV, we investigate empirically the predicted stellar mass function for LBGs.

  17. Physical and linkage mapping of the human and murine genes for the [alpha]1 chain of type IX collagen (COL9A1)

    Energy Technology Data Exchange (ETDEWEB)

    Warman, M.L. (Harvard Medical School, Boston, MA (United States) Children' s Hospital/Harvard Medical School, Boston, MA (United States)); Tiller, G.E.; Polumbo, P.A. (Vanderbilt Univ. Medical Center, Nashville, TN (United States)); Seldin, M.F.; Rochelle, J.M. (Duke Univ. Medical Center, Durham, NC (United States)); Knoll, J.H.M.; Cheng, Sou De (Children' s Hospital/Harvard Medical School, Boston, MA (United States)); Olsen, B.R. (Harvard Medical School, Boston, MA (United States))

    1993-09-01

    The IX collagen, a member of the FACIT family of extracellular matrix proteins, is a heterotrimer composed of three genetically distinct [alpha] chains. The cDNAs for the human and mouse [alpha]1(IX) chains have been cloned. In this paper the authors confirm the mapping of the human COL9A1 gene to chromosome 6q12-q13 by fluorescence in situ hybridization utilizing two genomic clones which also contain short tandem repeat polymorphisms. They also report the characterization of these repeats and their incorporation into the chromosome 6 linkage map. The COL9A1 locus shows no recombination with the marker D6Z1 (Z = 27.61 at [theta] = 0) and identifies the most likely locus order of KRAS1P-[D6Z1-COL9A1]-D6S30. In addition, using an interspecific backcross panel, they have mapped murine Col9a1 to mouse chromosome 1. Together with other comparative mapping results, these data suggest that the pericentric region of human chromosome 6 is homologous to the most proximal segment of mouse chromosome 1. These data may facilitate linkage studies with COL9A1 (or col9a1) as a candidate gene for hereditary chondrodysplasias and osteoarthritis. 35 refs., 2 figs., 2 tabs.

  18. Origin of the Lyman excess in early-type stars

    CERN Document Server

    Cesaroni, R; Beltrán, M T; Molinari, S; Olmi, L; Treviño-Morales, S P

    2016-01-01

    Ionized regions around early-type stars are believed to be well-known objects, but until recently, our knowledge of the relation between the free-free radio emission and the IR emission has been observationally hindered by the limited angular resolution in the far-IR. The advent of Herschel has now made it possible to obtain a more precise comparison between the two regimes, and it has been found that about a third of the young HII regions emit more Lyman continuum photons than expected, thus presenting a Lyman excess. With the present study we wish to distinguish between two scenarios that have been proposed to explain the existence of the Lyman excess: (i) underestimation of the bolometric luminosity, or (ii) additional emission of Lyman-continuum photons from an accretion shock. We observed an outflow (SiO) and an infall (HCO+) tracer toward a complete sample of 200 HII regions, 67 of which present the Lyman excess. Our goal was to search for any systematic difference between sources with Lyman excess and ...

  19. Green Peas and diagnostics for Lyman continuum leaking in star-forming dwarf galaxies

    Science.gov (United States)

    Thuan, Trinh

    2014-10-01

    One of the key questions in observational cosmology is the identification of the sources responsible for cosmic reionization. The general consensus is that a population of faint low-mass galaxies must be responsible for the bulk of the ionizing photons. However, attempts at identifying individual galaxies showing Lyman continuum (LyC) leakage have so far not been successful, both at high and low redshifts. We propose here to observe directly the LyC of five so-called "Green Pea" (GP) galaxies. GPs share many of the properties of the Lyman Break galaxies at high z (compactness, low mass, low metallicity, high specific star formation rate, gas-rich and clumpy morphology) and may constitute local examples of the long sought-after LyC leaking galaxies. The five GPs have been identified by searching the Sloan Data Release 10 spectral data base of 2 million spectra for non-AGN emission-line objects that meet the following criteria: high [OIII]5007/[OII]3727 ratios, large GALEX FUV fluxes, and redshifted enough (z~0.3) so that the LyC is shifted into the sensitive spectral range of COS. Our unique GP sample will allow us to combine for the first time four fundamental tests for LyC leaking in galaxies and validate their usefulness as LyC leaking indicators : 1) direct measurements of the LyC; 2) high [OIII]/[OII] ratios; 3) characteristics of the Lyman alpha line profile; and 4) residual intensities in the low-ionization ISM absorption UV lines.

  20. Mapping of the serotonin 5-HT{sub 1D{alpha}} autoreceptor gene (HTR1D) on chromosome 1 using a silent polymorphism in the coding region

    Energy Technology Data Exchange (ETDEWEB)

    Ozaki, N.; Lappalainen, J.; Linnoila, M. [National Institute on Alcohol Abuse and Alcoholism, Rockville, MD (United States)] [and others

    1995-04-24

    Serotonin (5-HT){sub ID} receptors are 5-HT release-regulating autoreceptors in the human brain. Abnormalities in brain 5-HT function have been hypothesized in the pathophysiology of various psychiatric disorders, including obsessive-compulsive disorder, autism, mood disorders, eating disorders, impulsive violent behavior, and alcoholism. Thus, mutations occurring in 5-HT autoreceptors may cause or increase the vulnerability to any of these conditions. 5-HT{sub 1D{alpha}} and 5-HT{sub 1D{Beta}} subtypes have been previously localized to chromosomes 1p36.3-p34.3 and 6q13, respectively, using rodent-human hybrids and in situ localization. In this communication, we report the detection of a 5-HT{sub 1D{alpha}} receptor gene polymorphism by single strand conformation polymorphism (SSCP) analysis of the coding sequence. The polymorphism was used for fine scale linkage mapping of 5-HT{sub 1D{alpha}} on chromosome 1. This polymorphism should also be useful for linkage studies in populations and in families. Our analysis also demonstrates that functionally significant coding sequence variants of the 5-HT{sub 1D{alpha}} are probably not abundant either among alcoholics or in the general population. 14 refs., 1 fig., 1 tab.

  1. Detection of high Lyman continuum leakage from four low-redshift compact star-forming galaxies

    CERN Document Server

    Izotov, Y I; Thuan, T X; Worseck, G; Orlitova, I; Verhamme, A

    2016-01-01

    Following our first detection reported in Izotov et al. (2016), we present the detection of Lyman continuum (LyC) radiation of four other compact star-forming galaxies observed with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST). These galaxies, at redshifts of z~0.3, are characterized by high emission-line flux ratios [OIII]5007/[OII]3727 > 5. The escape fractions of the LyC radiation fesc(LyC) in these galaxies are in the range of ~6%-13%, the highest values found so far in low-redshift star-forming galaxies. Narrow double-peaked Lyalpha emission lines are detected in the spectra of all four galaxies, compatible with predictions for Lyman continuum leakers. We find escape fractions of Lyalpha, fesc(Lyalpha) ~60%-90%, among the highest known for Lyalpha emitters (LAEs). Surface brightness profiles produced from the COS acquisition images reveal bright star-forming regions in the center and exponential discs in the outskirts with disc scale lengths alpha in the range ~0.6-1.4 k...

  2. The Cosmic Evolution of the Metallicity Distribution of Ionized Gas Traced by Lyman Limit Systems

    CERN Document Server

    Lehner, Nicolas; Howk, J Christopher; Prochaska, J Xavier; Fumagalli, Michele

    2016-01-01

    We present the first results from our KODIAQ Z survey aimed to determine the metallicity distribution and physical properties of the partial and full Lyman limit systems (pLLSs and LLSs; 16.22, which probe gas in the interface regions between the intergalactic medium and galaxies. We study 31 HI-selected pLLSs and LLSs at 2.3Lyman alpha absorbers (DLAs) at any given z, and this fraction remains relatively constant from z<1 to z~2-4. There is therefore a reservoir of metal-poor cool gas at all z that ma...

  3. The Keck+Magellan Survey for Lyman Limit Absorption III: Sample Definition and Column Density Measurements

    CERN Document Server

    Prochaska, J Xavier; Fumagalli, Michele; Bernstein, Rebecca A; Burles, Scott M

    2015-01-01

    We present an absorption-line survey of optically thick gas clouds -- Lyman Limit Systems (LLSs) -- observed at high dispersion with spectrometers on the Keck and Magellan telescopes. We measure column densities of neutral hydrogen NHI and associated metal-line transitions for 157 LLSs at z=1.76-4.39 restricted to 10^17.3 < NHI < 10^20.3. An empirical analysis of ionic ratios indicates an increasing ionization state of the gas with decreasing NHI and that the majority of LLSs are highly ionized, confirming previous expectations. The Si^+/H^0 ratio spans nearly four orders-of-magnitude, implying a large dispersion in the gas metallicity. Fewer than 5% of these LLSs have no positive detection of a metal transition; by z~3, nearly all gas that is dense enough to exhibit a very high Lyman limit opacity has previously been polluted by heavy elements. We add new measurements to the small subset of LLS (~5-10) that may have super-solar abundances. High Si^+/Fe^+ ratios suggest an alpha-enhanced medium whereas ...

  4. Indirect Evidence for Escaping Ionizing Photons in Local Lyman Break Galaxy Analogs

    CERN Document Server

    Alexandroff, Rachael; Borthakur, Sanchayeeta; Overzier, Roderik; Leitherer, Claus

    2015-01-01

    A population of early star-forming galaxies is the leading candidate for the re-ionization of the universe. It is still unclear what conditions and physical processes would enable a significant fraction of the ionizing photons to escape from these gas-rich galaxies. In this paper we present the results of the analysis of HST COS far-UV spectroscopy plus ancillary multi-waveband data of a sample of 22 low-redshift galaxies that are good analogs to typical star-forming galaxies at high-redshift. We measure three parameters that provide indirect evidence of the escape of ionizing radiation: (1) the residual intensity in the cores of saturated interstellar low-ionization absorption-lines. (2) The relative amount of blue-shifted Lyman alpha line emission, and (3) the relative weakness of the [SII] optical emission lines. We use these diagnostics to rank-order our sample in terms of likely leakiness, noting that a direct measure of escaping Lyman continuum has recently been made for one of the leakiest members of o...

  5. Star Formation from DLA Gas in the Outskirts of Lyman Break Galaxies at z~3

    CERN Document Server

    Rafelski, Marc; Chen, Hsiao-Wen

    2010-01-01

    We present evidence for spatially extended low surface brightness emission around Lyman break galaxies (LBGs) in the V-band image of the Hubble Ultra Deep Field, corresponding to the z~3 rest-frame FUV light, which is a sensitive measure of Star Formation Rates (SFRs). We find that the covering fraction of molecular gas at z~3 is not adequate to explain the emission in the outskirts of LBGs, while the covering fraction of neutral atomic-dominated hydrogen gas at high redshift is sufficient. We develop a theoretical framework to connect this emission around LBGs to the expected emission from neutral H I gas i.e., Damped Lyman Alpha systems (DLAs), using the Kennicutt-Schmidt (KS) relation. Working under the hypothesis that the observed FUV emission in the outskirts of LBGs is from in-situ star formation in atomic-dominated hydrogen gas, the results suggest that the SFR efficiency in such gas at z~3 is between factors of 10 and 50 lower than predictions based on the local KS relation. The total star formation r...

  6. Clustering of Ly alpha emitters at z approximate to 4.5

    NARCIS (Netherlands)

    Kovac, Katarina; Somerville, Rachel S.; Rhoads, James E.; Malhotra, Sangeeta; Wang, JunXian

    2007-01-01

    We present the clustering properties of 151 Ly alpha-emitting galaxies at z approximate to 4.5 selected from the Large Area Lyman Alpha (LALA) survey. Our catalog covers an area of 36'; 36' observed with five narrowband filters. We assume that the angular correlation function w(theta) is well repres

  7. Clustering of Ly alpha emitters at z approximate to 4.5

    NARCIS (Netherlands)

    Kovac, Katarina; Somerville, Rachel S.; Rhoads, James E.; Malhotra, Sangeeta; Wang, JunXian

    2007-01-01

    We present the clustering properties of 151 Ly alpha-emitting galaxies at z approximate to 4.5 selected from the Large Area Lyman Alpha (LALA) survey. Our catalog covers an area of 36'; 36' observed with five narrowband filters. We assume that the angular correlation function w(theta) is well

  8. - X (1)Sigma(+)((g)) (v ''=0) Lyman bands in H-2 and HD

    NARCIS (Netherlands)

    Hollenstein, U.; Reinhold, E.M.; Lange, de C.A.; Ubachs, W.M.G.

    2006-01-01

    - X (1)Sigma(+) (v" = 0) Lyman bands in HD are presented using a narrow bandwidth vacuum ultraviolet laser system combined with an accurate frequency calibration. These measurements complete the recently published data on the Lyman frequency transitions of Philip.

  9. Comparative mapping of a gorilla-derived alpha satellite DNA clone on great ape and human chromosomes.

    Science.gov (United States)

    Baldini, A; Miller, D A; Shridhar, V; Rocchi, M; Miller, O J; Ward, D C

    1991-11-01

    We have isolated an alpha satellite DNA clone, pG3.9, from gorilla DNA. Fluorescence in situ hybridization on banded chromosomes under high stringency conditions revealed that pG3.9 identifies homologous sequences at the centromeric region of ten gorilla chromosomes, and, with few exceptions, also recognizes the homologous chromosomes in human. A pG3.9-like alphoid DNA is present on a larger number of orangutan chromosomes, but, in contrast, is present on only two chromosomes in the chimpanzee. These results show that the chromosomal subsets of related alpha satellite DNA sequences may undergo different patterns of evolution.

  10. Mapping of nuclear import signal and importin {alpha}3 binding regions of 52K protein of bovine adenovirus-3

    Energy Technology Data Exchange (ETDEWEB)

    Paterson, Carolyn P.; Ayalew, Lisanework E. [Vaccine and Infectious Disease Organization-International Vaccine Center (VIDO-InterVac), University of Saskatchewan, Saskatoon, SK S7N 5E3 Canada (Canada); Veterinary Microbiology, University of Saskatchewan, Saskatoon, SK S7N 5E3 S7N 5B4 Canada (Canada); Tikoo, Suresh K., E-mail: suresh.tik@usask.ca [Vaccine and Infectious Disease Organization-International Vaccine Center (VIDO-InterVac), University of Saskatchewan, Saskatoon, SK S7N 5E3 Canada (Canada); Veterinary Microbiology, University of Saskatchewan, Saskatoon, SK S7N 5E3 S7N 5B4 Canada (Canada); School of Public Health, University of Saskatchewan, Saskatoon, SK S7N 5E5 Canada (Canada)

    2012-10-10

    The L1 region of bovine adenovirus (BAdV)-3 encodes a non-structural protein designated 52K. Anti-52K serum detected a protein of 40 kDa, which localized to the nucleus but not to the nucleolus in BAdV-3-infected or transfected cells. Analysis of mutant 52K proteins suggested that three basic residues ({sup 105}RKR{sup 107}) of the identified domain (amino acids {sup 102}GMPRKRVLT{sup 110}) are essential for nuclear localization of 52K. The nuclear import of a GST-52K fusion protein utilizes the classical importin {alpha}/{beta}-dependent nuclear transport pathway. The 52K protein is preferentially bound to the cellular nuclear import receptor importin {alpha}3. Although deletion of amino acid 102-110 is sufficient to abrogate the nuclear localization of 52K, amino acid 90-133 are required for interaction with importin-{alpha}3 and localizing a cytoplasmic protein to the nucleus. These results suggest that 52K contains a bipartite NLS, which preferentially utilize an importin {alpha}3 nuclear import receptor-mediated pathway to transport 52K to the nucleus.

  11. AXUV bolometer and Lyman-α camera systems on the TCV tokamak

    Science.gov (United States)

    Degeling, A. W.; Weisen, H.; Zabolotsky, A.; Duval, B. P.; Pitts, R. A.; Wischmeier, M.; Lavanchy, P.; Marmillod, Ph.; Pochon, G.

    2004-10-01

    A set of seven twin slit cameras, each containing two 20-element linear absolute extreme ultraviolet photodiode arrays, has been installed on the Tokamak à Configuration Variable. One array in each camera will operate as a bolometer and the second as a Lyman-alpha (Lα) emission monitor for estimating the recycled neutral flux. The camera configuration was optimized by simulations of tomographic reconstructions of the expected Lα emission. The diagnostic will provide spatial and temporal resolution (10 μs) of the radiated power and the Lα emission that is considerably higher than previously achieved. This optimism is justified by extensive experience with prototype systems, which include first measurements of Lα light from the divertor.

  12. Voyager measurements of hydrogen Lyman-α diffuse emission from the Milky Way.

    Science.gov (United States)

    Lallement, Rosine; Quémerais, Eric; Bertaux, Jean-Loup; Sandel, Bill R; Izmodenov, Vlad

    2011-12-23

    Doppler-shifted hydrogen Lyman-alpha (Lyα) emission from galaxies is currently measured and used in cosmology as an indicator of star formation. Until now, the Milky Way emission has not been detected, owing to far brighter local sources, including the H (hydrogen) glow, i.e., solar Lyα radiation backscattered by interstellar atoms that flow within the solar system. Because observations from the Voyager spacecraft, now leaving the heliosphere, are decreasingly affected by the H glow, the ultraviolet spectrographs are detecting Lyα diffuse emission from our Galaxy. The surface brightness toward nearby star-forming regions is about 3 to 4 rayleighs. The escape fraction of the radiation from the brightest H II regions is on the order of 3% and is highly spatially variable. These results will help in constraining models of Lyα radiation transfer in distant galaxies.

  13. The puzzle of the lyman continuum polarization of qsos

    Directory of Open Access Journals (Sweden)

    Gregory A. Shields

    2001-01-01

    Full Text Available Mediante espectropolarimetr a reciente de cuasares se ha encontrado un sor- prendente incremento en la polarizaci on del cont nuo de Lyman en varios objetos. Discutimos algunos intentos recientes para explicar este hecho, que incluyen el papel de la absorci on de Lyman en PG 1222+228. Presentamos nuevos resultados te oricos que involucran dispersi on por electrones en una corona caliente o en un viento por encima de un disco de acreci on, y la polarizaci on que resulta del efecto relativista de la radiaci on que regresa. Potencialemente estos mecanismos pueden alcanzar niveles de polarizaci on observables en longitudes de onda cortas, pero ninguno logra ex- plicar cuantitativamente los incrementos en la polarizaci on del cont nuo de Lyman. Se requiere urgentemente mayor capacidad para llevar a cabo espectropolarimetr a en el ultravioleta desde sat elites para esclarecer este fen omeno.

  14. Incorporating Single-nucleotide Polymorphisms Into the Lyman Model to Improve Prediction of Radiation Pneumonitis

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, Susan L., E-mail: sltucker@mdanderson.org [Department of Bioinformatics and Computational Biology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Li Minghuan [Department of Radiation Oncology, Shandong Cancer Hospital, Jinan, Shandong (China); Xu Ting; Gomez, Daniel [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Yuan Xianglin [Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China); Yu Jinming [Department of Radiation Oncology, Shandong Cancer Hospital, Jinan, Shandong (China); Liu Zhensheng; Yin Ming; Guan Xiaoxiang; Wang Lie; Wei Qingyi [Department of Epidemiology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Mohan, Radhe [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Vinogradskiy, Yevgeniy [University of Colorado School of Medicine, Aurora, Colorado (United States); Martel, Mary [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Liao Zhongxing [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

    2013-01-01

    Purpose: To determine whether single-nucleotide polymorphisms (SNPs) in genes associated with DNA repair, cell cycle, transforming growth factor-{beta}, tumor necrosis factor and receptor, folic acid metabolism, and angiogenesis can significantly improve the fit of the Lyman-Kutcher-Burman (LKB) normal-tissue complication probability (NTCP) model of radiation pneumonitis (RP) risk among patients with non-small cell lung cancer (NSCLC). Methods and Materials: Sixteen SNPs from 10 different genes (XRCC1, XRCC3, APEX1, MDM2, TGF{beta}, TNF{alpha}, TNFR, MTHFR, MTRR, and VEGF) were genotyped in 141 NSCLC patients treated with definitive radiation therapy, with or without chemotherapy. The LKB model was used to estimate the risk of severe (grade {>=}3) RP as a function of mean lung dose (MLD), with SNPs and patient smoking status incorporated into the model as dose-modifying factors. Multivariate analyses were performed by adding significant factors to the MLD model in a forward stepwise procedure, with significance assessed using the likelihood-ratio test. Bootstrap analyses were used to assess the reproducibility of results under variations in the data. Results: Five SNPs were selected for inclusion in the multivariate NTCP model based on MLD alone. SNPs associated with an increased risk of severe RP were in genes for TGF{beta}, VEGF, TNF{alpha}, XRCC1 and APEX1. With smoking status included in the multivariate model, the SNPs significantly associated with increased risk of RP were in genes for TGF{beta}, VEGF, and XRCC3. Bootstrap analyses selected a median of 4 SNPs per model fit, with the 6 genes listed above selected most often. Conclusions: This study provides evidence that SNPs can significantly improve the predictive ability of the Lyman MLD model. With a small number of SNPs, it was possible to distinguish cohorts with >50% risk vs <10% risk of RP when they were exposed to high MLDs.

  15. Chromosomal location of two human genes encoding tetrahydrobiopterin-metabolizing enzymes: 6-pyruvoyl-tetrahydropterin synthase maps to 11q22. 3-q23. 3, and pterin-4[alpha]-carbinolamine dehydratase maps to 10q22

    Energy Technology Data Exchange (ETDEWEB)

    Thoeny, B.; Heizmann, C.W. (Univ. of Zuerich (Switzerland)); Mattei, M.G. (Institut National de la Sante et de la Recherche Medicale, Marseille (France))

    1994-01-15

    Tetrahydrobiopterin (BH[sub 4]) is the redox cofactor for the aromatic amino acid hydroxylases such as phenylalanine hydroxylase. At least five enzymes are known to be involved in BH[sub 4] biosynthesis and regeneration. A deficiency in several of the BH[sub 4] metabolic enzymes causes variant types of hyperphenylalaninemias in man. Recently, the authors cloned and expressed the human cDNAs for two of the BH[sub 4] enzymes, the 6-pyruvoyl-tetrahydropterin synthase and the pterin-4[alpha]-carbinolamine dehydratase (gene symbols PTS and PCD/DCOH, respectively). In this report, they localized the two genes on the human chromsomes by in situ hybridization. The PTS gene was mapped to the chromosomal region 11q22.3-q23.3, and the PCD/DCOH gene was mapped to the 10q22 band of the genome. 18 refs., 2 figs.

  16. $Ly \\alpha$ Fluorescent Excitation of FeII in Active Galactic Nuclei

    CERN Document Server

    Sigut, T A A; Pradhan, Anil K.

    1998-01-01

    We have calculated FeII emission line strengths for Active Galactic Nuclei Broad-Line Regions using precise radiative transfer and Iron Project atomic data. We improve the treatment of all previously considered excitation mechanisms for the FeII emission, continuum fluorescence, collisional excitation, fluorescence by self-overlap among the iron lines, and fluorescent excitation by Lyman-alpha. We demonstrate that Lyman-alpha fluorescence is of fundamental importance in determining the strength of the FeII emission. In addition to enhancing the ultraviolet and optical FeII flux, Lyman-alpha fluorescence also results in significant near-infrared FeII emission in the 8500-9500 Angstrom wavelength range. New observations are suggested to probe this effect in strong FeII emitting quasars.

  17. Mapping alpha-helical induced folding within the intrinsically disordered C-terminal domain of the measles virus nucleoprotein by site-directed spin-labeling EPR spectroscopy.

    Science.gov (United States)

    Belle, Valérie; Rouger, Sabrina; Costanzo, Stéphanie; Liquière, Elodie; Strancar, Janez; Guigliarelli, Bruno; Fournel, André; Longhi, Sonia

    2008-12-01

    Using site-directed spin-labeling EPR spectroscopy, we mapped the region of the intrinsically disordered C-terminal domain of measles virus nucleoprotein (N(TAIL)) that undergoes induced folding. In addition to four spin-labeled N(TAIL) variants (S407C, S488C, L496C, and V517C) (Morin et al. (2006), J Phys Chem 110: 20596-20608), 10 new single-site cysteine variants were designed, purified from E. coli, and spin-labeled. These 14 spin-labeled variants enabled us to map in detail the gain of rigidity of N(TAIL) in the presence of either the secondary structure stabilizer 2,2,2-trifluoroethanol or the C-terminal domain X (XD) of the viral phosphoprotein. Different regions of N(TAIL) were shown to contribute to a different extent to the binding to XD, while the mobility of the spin labels grafted at positions 407 and 460 was unaffected upon addition of XD; that of the spin labels grafted within the 488-502 and the 505-522 regions was severely and moderately reduced, respectively. Furthermore, EPR experiments in the presence of 30% sucrose allowed us to precisely map to residues 488-502, the N(TAIL) region undergoing alpha-helical folding. The mobility of the 488-502 region was found to be restrained even in the absence of the partner, a behavior that could be accounted for by the existence of a transiently populated folded state. Finally, we show that the restrained motion of the 505-522 region upon binding to XD is due to the alpha-helical transition occurring within the 488-502 region and not to a direct interaction with XD.

  18. A LYMAN BREAK GALAXY IN THE EPOCH OF REIONIZATION FROM HUBBLE SPACE TELESCOPE GRISM SPECTROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Rhoads, James E.; Malhotra, Sangeeta; Cohen, Seth; Zheng Zhenya [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Dickinson, Mark [National Optical Astronomy Observatory, Tucson, AZ (United States); Pirzkal, Norbert; Grogin, Norman; Koekemoer, Anton; Peth, Michael A. [Space Telescope Science Institute, Baltimore, MD (United States); Spinrad, Hyron [University of California, Berkeley, CA (United States); Reddy, Naveen [University of California, Riverside, CA (United States); Hathi, Nimish [Observatories of the Carnegie Institution of Washington, Pasadena, CA (United States); Budavari, Tamas [Johns Hopkins University, Baltimore, MD (United States); Ferreras, Ignacio [Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom); Gardner, Jonathan P. [NASA Goddard Space Flight Center, Astrophysics Science Division, Observational Cosmology Laboratory, Code 665, Greenbelt, MD 20771 (United States); Gronwall, Caryl [Department of Astronomy and Astrophysics, and Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802 (United States); Haiman, Zoltan [Columbia University, New York, NY (United States); Kuemmel, Martin [Universitaets-Sternwarte Muenchen, Scheinerstr. 1, D-81679 Muenchen (Germany); Meurer, Gerhardt, E-mail: James.Rhoads@asu.edu [International Centre for Radio Astronomy Research, University of Western Australia, M468, 35 Stirling Highway, Crawley, WA 6009 (Australia); and others

    2013-08-10

    We present observations of a luminous galaxy at z = 6.573-the end of the reionization epoch-which has been spectroscopically confirmed twice. The first spectroscopic confirmation comes from slitless Hubble Space Telescope Advanced Camera for Surveys grism spectra from the PEARS survey (Probing Evolution And Reionization Spectroscopically), which show a dramatic continuum break in the spectrum at rest frame 1216 A. The second confirmation is done with Keck + DEIMOS. The continuum is not clearly detected with ground-based spectra, but high wavelength resolution enables the Ly{alpha} emission line profile to be determined. We compare the line profile to composite line profiles at z = 4.5. The Ly{alpha} line profile shows no signature of a damping wing attenuation, confirming that the intergalactic gas is ionized at z = 6.57. Spectra of Lyman breaks at yet higher redshifts will be possible using comparably deep observations with IR-sensitive grisms, even at redshifts where Ly{alpha} is too attenuated by the neutral intergalactic medium to be detectable using traditional spectroscopy from the ground.

  19. The nature of proximate damped Lyman α systems

    NARCIS (Netherlands)

    Ellison, S.L.; Prochaska, J.X.; Hennawi, J.; Lopez, S.; Usher, C.; Wolfe, A.M.; Russell, D.M.; Benn, C.R.

    2010-01-01

    We present high-resolution echelle spectra of seven proximate damped Lyman α (PDLA) systems. The relative velocity separation of each PDLA from the background quasar is ΔV < 3000 km s−1. Combining our sample with a further nine PDLAs from the literature we compare the chemical properties of the prox

  20. Hot workability of {gamma} + {alpha}{sub 2} titanium aluminide: Development of processing map and constitutive equations

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R.K., E-mail: rohitkumar_gupta@vssc.gov.in [Vikram Sarabhai Space Centre, ISRO, Trivandrum 695 022 (India); Narayana Murty, S.V.S.; Pant, Bhanu [Vikram Sarabhai Space Centre, ISRO, Trivandrum 695 022 (India); Agarwala, Vijaya [Indian Institute of Technology, Roorkee, Roorkee 247 667 (India); Sinha, P.P. [Vikram Sarabhai Space Centre, ISRO, Trivandrum 695 022 (India)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Deformation studies of five TiAl alloys carried out through processing map. Black-Right-Pointing-Pointer DRX domain and superplastic domain identified in power efficiency map. Black-Right-Pointing-Pointer Safe working zone for alloys found at 1223-1423 K at strain rates (10{sup -2}-10{sup -3} s{sup -1}). Black-Right-Pointing-Pointer Strain rate sensitivity, activation energy, Zener Hollomon parameter (Z) are obtained. Black-Right-Pointing-Pointer Constitutive equations derived and verified. DRX grain size correlated with Z. - Abstract: Gamma titanium alumindes are intermetallics, which have very narrow working range. Hot isothermal working is the most suitable process for hot working of alloy. Accordingly, hot isothermal compression test is carried out on reaction synthesized and homogenized titanium aluminide alloys at different temperatures and strain rates using Gleeble thermomechanical simulator. Three alloys of Ti48Al2Cr2Nb0.1B (atom%) have been used in the study. Stress-strain data obtained from the test has been used to construct processing map, which indicates the safe and unsafe working zone. Strain rate sensitivity and Zener-Hollomon parameter has been calculated. Further, constitutive equations have been generated and verified. It is found that alloy has good workability in the temperature range of 1223-1423 K at strain rates of 0.01-0.001 s{sup -1}. In this range of parameters, the alloys nearly follow the constitutive equations.

  1. Mono-PEGylation of Alpha-MMC and MAP30 from Momordica charantia L.: Production, Identification and Anti-Tumor Activity.

    Science.gov (United States)

    Sun, Yun; Sun, Fenghui; Li, Jianlong; Wu, Minlu; Fan, Xiang; Meng, Yanfa; Meng, Yao

    2016-10-31

    PEGylation is a well-established and effective strategy to decrease immunogenicity, which can increase the stability and in vivo half-life time. However, the generation of multi-site modified products is inevitable due to the lysine chemistry, which will bring difficulties in subsequent research, such as purification and quantification. Site-specific modification by mPEG-succinimidyl carbonate (mPEG-SC) is a widely used method for N-terminal conjugation. In this study, we used it for site-directed modification on two ribosome-inactivating proteins (RIPs), alpha-momorcharin (α-MMC) and momordica anti-HIV protein (MAP30), from Momordica charantia L. According to the optimization of previous modification conditions, we compared Macro-Cap SP with SP-Sepharose FF chromatography for separating the final mPEGylated RIPs. Two kinds of methods both can obtain homogenous mPEGylated RIPs which were identified by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE), isoelectric focusing electrophoresis (IEF), and matrix-assisted laser desorption ionization-time of flight/time of flight (MALDI-TOF/TOF) analysis. We also used iodine staining method to detect the amount of unmodified PEG. Furthermore, the inhibition activity of both mPEGylated and non-PEGylated RIPs against human lung adenocarcinoma epithelial A549 cells was detected. All of the results suggested that the mPEGylated α-MMC/MAP30 might be potentially developed as new anti-tumor drugs.

  2. Discovery of 4-(5-(Cyclopropylcarbamoyl)-2-methylphenylamino)-5-methyl-N-propylpyrrolo[1,2-f][1,2,4]triazine-6-carboxamide (BMS-582949), a Clinical p38[alpha] MAP Kinase Inhibitor for the Treatment of Inflammatory Diseases

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chunjian; Lin, James; Wrobleski, Stephen T.; Lin, Shuqun; Hynes, Jr., John; Wu, Hong; Dyckman, Alaric J.; Li, Tianle; Wityak, John; Gillooly, Kathleen M.; Pitt, Sidney; Shen, Ding Ren; Zhang, Rosemary F.; McIntyre, Kim W.; Salter-Cid, Luisa; Shuster, David J.; Zhang, Hongjian; Marathe, Punit H.; Doweyko, Arthur M.; Sack, John S.; Kiefer, Susan E.; Kish, Kevin F.; Newitt, John A.; McKinnon, Murray; Dodd, John H.; Barrish, Joel C.; Schieven, Gary L.; Leftheris, Katerina (BMS)

    2013-11-20

    The discovery and characterization of 7k (BMS-582949), a highly selective p38{alpha} MAP kinase inhibitor that is currently in phase II clinical trials for the treatment of rheumatoid arthritis, is described. A key to the discovery was the rational substitution of N-cyclopropyl for N-methoxy in 1a, a previously reported clinical candidate p38{alpha} inhibitor. Unlike alkyl and other cycloalkyls, the sp{sup 2} character of the cyclopropyl group can confer improved H-bonding characteristics to the directly substituted amide NH. Inhibitor 7k is slightly less active than 1a in the p38{alpha} enzymatic assay but displays a superior pharmacokinetic profile and, as such, was more effective in both the acute murine model of inflammation and pseudoestablished rat AA model. The binding mode of 7k with p38{alpha} was confirmed by X-ray crystallographic analysis.

  3. The Environmental Impact of Lyman-break Galaxies

    CERN Document Server

    Tasker, E J; Bryan, Greg L.; Tasker, Elizabeth J.

    2006-01-01

    We perform cosmological simulations of galaxies forming at z=3 using the hydrodynamics grid code, Enzo. By selecting the largest galaxies in the volume to correspond to Lyman-break galaxies, we construct observational spectra of the HI flux distribution around these objects, as well as column densities of CIV and OVI throughout a refined region. We successfully reproduce the most recent observations of the mean HI flux in the close vicinity of Lyman-break galaxies but see no evidence for the proximity effect in earlier observations. While our galaxies do return metals to the IGM, their quantity and volume appears to be somewhat less than observed. We conclude that either we do not adequately resolve galactic winds, or that at least some of the intergalactic metal enrichment is by early epoch objects whose mass is smaller than our minimum resolved halo mass.

  4. Lyman Break Galaxies and the Reionization of the Intergalactic Medium

    CERN Document Server

    Ferguson, H C; Papovich, C; Ferguson, Henry C.; Dickinson, Mark; Papovich, Casey

    2002-01-01

    Near-infrared observations of Lyman-break galaxies at redshifts z~3 are beginning to provide constraints on ages, star-formation histories, dust content, metallicities, and stellar masses. At present, uncertainties of more than an order of magnitude are typical for many of these parameters. It is nonetheless interesting to ask what the stellar-population models imply for the existence and luminosities of Lyman-break galaxies at higher redshift. To this end we examine the inferred star-formation rates in two well-studied samples of galaxies as a function of redshift out to z = 10 for various best-fit and limiting cases. Taken at face value, the generally young ages (typically 10^8 +- 0.5 yr) of the z = 3 Lyman break galaxies imply that their stars were not present much beyond z=4. By z = 6 the cosmic star-formation rate from the progenitors of these galaxies is less than 10% of star-formation rate at z=3 +- 0.5, even for maximally-old models, provided the derivative of the star-formation rate SFR(t) is monoton...

  5. Mapping the Polarization of the Radio-Loud Ly$\\alpha$ Nebula B3 J2330+3927

    CERN Document Server

    You, Chang; Smith, Paul; Yang, Yujin; Kim, Eunchong; Jannuzi, Buell; Prescott, Moire K M; Matsuda, Yuichi; Lee, Myung Gyoon

    2016-01-01

    Lya nebulae, or "Lya blobs", are extended (up to ~100 kpc), bright (L[Lya] > 10^43 erg/s) clouds of Lya emitting gas that tend to lie in overdense regions at z ~ 2--5. The origin of the Lya emission remains unknown, but recent theoretical work suggests that measuring the polarization might discriminate among powering mechanisms. Here we present the first narrowband, imaging polarimetry of a radio-loud Lya nebula, B3 J2330+3927 at z=3.09, with an embedded active galactic nucleus (AGN). The AGN lies near the blob's Lya emission peak and its radio lobes align roughly with the blob's major axis. With the SPOL polarimeter on the 6.5m MMT telescope, we map the total (Lya + continuum) polarization in a grid of circular apertures of radius 0.6" (4.4kpc), detecting a significant (>2sigma) polarization fraction P in nine apertures and achieving strong upper-limits (as low as 2%) elsewhere. P increases from <2% at ~5kpc from the blob center to ~17% at ~15-25kpc. The detections are distributed asymmetrically, roughly ...

  6. Medium-resolution spectroscopy of FORJ0332-3557: Probing the interstellar medium and stellar populations of a lensed Lyman-break galaxy at z=3.77

    CERN Document Server

    Cabanac, Remi A; Lidman, Chris

    2008-01-01

    We recently reported the discovery of FORJ0332-3557, a lensed Lyman-break galaxy at z=3.77 in a remarkable example of strong galaxy-galaxy gravitational lensing. We present here a medium-resolution rest-frame UV spectrum of the source, which appears to be similar to the well-known Lyman-break galaxy MS1512-cB58 at z=2.73. The spectral energy distribution is consistent with a stellar population of less than 30 Ma, with an extinction of A(V)=0.5 mag and an extinction-corrected star formation rate SFR(UV) of 200-300 Msun/a. The Lyman-alpha line exhibits a damped profile in absorption produced by a column density of about N(HI) = (2.5+_1.0) 10^21 atoms/cm^2, superimposed on an emission line shifted both spatially (0.5 arcsec with respect to the UV continuum source) and in velocity space (+830 km/s with respect to the low-ionisation absorption lines from its interstellar medium), a clear signature of outflows with an expansion velocity of about 270 km/s. A strong emission line from HeII 164.04nm indicates the pres...

  7. Inhibition of MAP kinase promotes the recruitment of corepressor SMRT by tamoxifen-bound estrogen receptor alpha and potentiates tamoxifen action in MCF-7 cells

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Wei, E-mail: hongwei@tijmu.edu.cn [Department of Immunology, Tianjin Medical University, 300070 Tianjin (China); Department of Laboratory Medicine, Tianjin Medical University, 300070 Tianjin (China); Chen, Linfeng [Department of Medical Oncology, Harvard Medical School, Dana Farber Cancer Institute, Boston, 02115 MA (United States); Li, Juan [Department of Laboratory Medicine, Tianjin Medical University, 300070 Tianjin (China); Yao, Zhi [Department of Immunology, Tianjin Medical University, 300070 Tianjin (China)

    2010-05-28

    Estrogen receptor alpha (ER{alpha}), a ligand controlled transcription factor, plays an important role in breast cancer growth and endocrine therapy. Tamoxifen (TAM) antagonizes ER{alpha} activity and has been applied in breast cancer treatment. TAM-bound ER{alpha} associates with nuclear receptor-corepressors. Mitogen-activated protein kinase (MAPK) has been elucidated to result in cross-talk between growth factor and ER{alpha} mediated signaling. We show that activated MAPK represses interaction of TAM-bound ER{alpha} with silencing mediator for retinoid and thyroid hormone receptors (SMRT) and inhibits the recruitment of SMRT by ER{alpha} to certain estrogen target genes. Blockade of MAPK signaling cascade with MEK inhibitor U0126 promotes the interaction and subsequently inhibits ER{alpha} activity via enhanced recruitment of SMRT, leading to reduced expression of ER{alpha} target genes. The growth rate of MCF-7 cells was decelerated when treated with both TAM and U0126. Moreover, the growth of MCF-7 cells stably expressing SMRT showed a robust repression in the presence of TAM and U0126. These results suggest that activated MAPK signaling cascade attenuates antagonist-induced recruitment of SMRT to ER{alpha}, suggesting corepressor mediates inhibition of ER{alpha} transactivation and breast cancer cell growth by antagonist. Taken together, our finding indicates combination of antagonist and MAPK inhibitor could be a helpful approach for breast cancer therapy.

  8. Alpha Thalassemia

    Science.gov (United States)

    Alpha Thalassemia Physicians often mistake alpha thalassemia trait for iron deficiency anemia and incorrectly prescribe iron supplements that have no effect 1 on the anemia. αα αα Normal alpha ...

  9. The Lyman β forest as a cosmic thermometer

    Energy Technology Data Exchange (ETDEWEB)

    Iršič, Vid [The Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, I-34151 Trieste (Italy); Viel, Matteo, E-mail: virsic@ictp.it, E-mail: viel@oats.inaf.it [INAF - Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, I-34143 Trieste (Italy)

    2014-12-01

    We present a comprehensive analysis of high resolution hydrodynamic simulations in terms of Lyman α and Lyman β one dimensional flux power spectra P{sub αα} and P{sub ββ}). In particular, we focus on the behaviour that the flux auto-power spectra and cross-power spectra P{sub αβ}) display when the intergalactic medium (IGM) thermal history is changed in a range of values that bracket a reference model, while cosmological parameters are kept fixed to best fit the cosmic microwave background data. We present empirical fits that describe at the sub-percent level the dependence of the power spectra on the thermal parameters. At the largest scales, the power spectra show a constant bias between each other that is set by the parameters describing the IGM thermal state. The cross-power spectrum has an oscillatory pattern and crosses zero at a scale which depends on T{sub 0}, the IGM temperature at the mean density, for reasonable values of the power-law index γ of the IGM temperature-density relation T=T{sub 0}(1+δ){sup γ-1}). By performing a Fisher matrix analysis, we find that the power spectrum P{sub ββ} is more sensitive to the thermal history than P{sub αα} alone, due to the fact that it probes denser regions than Lyman α. When we combine the power and cross spectra the constraints on γ can be improved by a factor ∼ 4, while the constraints on T{sub 0} improve by a factor of ∼ 2. We address the role of signal-to-noise and resolution by mocking realistic observations and we conclude that the framework presented in this work can significantly improve the knowledge of the IGM thermal state, which will in turn guarantee better constraints on IGM-derived cosmological parameters.

  10. The Bivariate Size-luminosity Relations for Lyman Break Galaxies at z ~ 4 - 5

    CERN Document Server

    Huang, Kuang-Han; Ravindranath, Swara; Su, Jian

    2013-01-01

    We study the bivariate size-luminosity distribution of Lyman Break Galaxies (LBGs) selected at redshifts around 4 and 5 in GOODS and the HUDF fields. We model the size-luminosity distribution as a combination of log-normal distribution (in size) and Schechter function (in luminosity), therefore it enables a more detailed study of the selection effects. We perform extensive simulations to quantify the dropout-selection completenesses and measurement biases and uncertainties in two-dimensional size and magnitude bins, and transform the theoretical size-luminosity distribution to the expected distribution for the observed data. Using maximum-likelihood estimator (MLE), we find that the Schechter function parameters for B-dropouts are \\alpha=-1.68^{+0.068}_{-0.095}, M*=-20.60^{+0.13}_{-0.17}, and \\phi*=1.79^{+0.32}_{-0.52} x 10^{-3} Mpc^{-3}. The log-normal size distribution is characterized by the peak R_0=1.34^{+0.099}_{-0.108} kpc at M_{1500}=-21 mag, width \\sigma_{\\lnR}=0.83^{+0.046}_{-0.044}, and the slope o...

  11. KECK SPECTROSCOPY OF FAINT 3 < z < 8 LYMAN BREAK GALAXIES: EVIDENCE FOR A DECLINING FRACTION OF EMISSION LINE SOURCES IN THE REDSHIFT RANGE 6 < z < 8

    Energy Technology Data Exchange (ETDEWEB)

    Schenker, Matthew A.; Ellis, Richard S.; Robertson, Brant E. [Department of Astrophysics, California Institute of Technology, MS 105-24, Pasadena, CA 91125 (United States); Stark, Daniel P. [Kavli Institute of Cosmology and Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Dunlop, James S.; McLure, Ross J. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Kneib, Jean-Paul [Laboratoire d' Astrophysique de Marseille, F-13388 Marseille cedex 13 (France); Richard, Johan [Observatoire de Lyon, F-69561 Saint-Genis-Laval (France)

    2012-01-10

    Using deep Keck spectroscopy of Lyman break galaxies selected from infrared imaging data taken with the Wide Field Camera 3 on board the Hubble Space Telescope, we present new evidence for a reversal in the redshift-dependent fraction of star-forming galaxies with detectable Lyman alpha (Ly{alpha}) emission in the redshift range 6.3 < z < 8.8. Our earlier surveys with the DEIMOS spectrograph demonstrated a significant increase with redshift in the fraction of line emitting galaxies over the interval 4 < z < 6, particularly for intrinsically faint systems which dominate the luminosity density. Using the longer wavelength sensitivities of Low Resolution Imaging Spectrometer and NIRSPEC, we have targeted 19 Lyman break galaxies selected using recent WFC3/IR data whose photometric redshifts are in the range 6.3 < z < 8.8 and which span a wide range of intrinsic luminosities. Our spectroscopic exposures typically reach a 5{sigma} sensitivity of <50 A for the rest-frame equivalent width (EW) of Ly{alpha} emission. Despite the high fraction of emitters seen only a few hundred million years later, we find only two convincing and one possible line emitter in our more distant sample. Combining with published data on a further seven sources obtained using FORS2 on the ESO Very Large Telescope, and assuming continuity in the trends found at lower redshift, we discuss the significance of this apparent reversal in the redshift-dependent Ly{alpha} fraction in the context of our range in continuum luminosity. Assuming all the targeted sources are at their photometric redshift and our assumptions about the Ly{alpha} EW distribution are correct, we would expect to find so few emitters in less than 1% of the realizations drawn from our lower redshift samples. Our new results provide further support for the suggestion that, at the redshifts now being probed spectroscopically, we are entering the era where the intergalactic medium is partially neutral. With the arrival of more

  12. Cross-correlation of the cosmic 21-cm signal and Lyman α emitters during reionization

    Science.gov (United States)

    Sobacchi, Emanuele; Mesinger, Andrei; Greig, Bradley

    2016-07-01

    Interferometry of the cosmic 21-cm signal is set to revolutionize our understanding of the Epoch of Reionization (EoR), eventually providing 3D maps of the early Universe. Initial detections however will be low signal to noise, limited by systematics. To confirm a putative 21-cm detection, and check the accuracy of 21-cm data analysis pipelines, it would be very useful to cross-correlate against a genuine cosmological signal. The most promising cosmological signals are wide-field maps of Lyman α emitting galaxies (LAEs), expected from the Subaru Hyper-Suprime Cam ultradeep field (UDF). Here we present estimates of the correlation between LAE maps at z ˜ 7 and the 21-cm signal observed by both the Low Frequency Array (LOFAR) and the planned Square Kilometre Array Phase 1 (SKA1). We adopt a systematic approach, varying both: (i) the prescription of assigning LAEs to host haloes; and (ii) the large-scale structure of neutral and ionized regions (i.e. EoR morphology). We find that the LAE-21cm cross-correlation is insensitive to (i), thus making it a robust probe of the EoR. A 1000 h observation with LOFAR would be sufficient to discriminate at ≳ 1σ a fully ionized Universe from one with a mean neutral fraction of bar{x}_{H I}≈ 0.50, using the LAE-21 cm cross-correlation function on scales of R ≈ 3-10 Mpc. Unlike LOFAR, whose detection of the LAE-21 cm cross-correlation is limited by noise, SKA1 is mostly limited by ignorance of the EoR morphology. However, the planned 100 h wide-field SKA1-Low survey will be sufficient to discriminate an ionized Universe from one with bar{x}_{H I}=0.25, even with maximally pessimistic assumptions.

  13. Mapping the subcellular distribution of alpha-synuclein in neurons using genetically encoded probes for correlated light and electron microscopy: Implications for Parkinson’s disease pathogenesis

    Science.gov (United States)

    Boassa, D.; Berlanga, M.L.; Yang, M.-L.; Terada, M.; Hu, J.; Bushong, E.A.; Hwang, M.; Masliah, E.; George, J.M.; Ellisman, M.H.

    2013-01-01

    Modifications to the gene encoding human alpha-synuclein have been linked to development of Parkinson’s disease. The highly conserved structure of alpha-synuclein suggests a functional interaction with membranes, and several lines of evidence point to a role in vesicle-related processes within nerve terminals. Using recombinant fusions of human alpha-synuclein including new genetic tags developed for correlated LM and EM (the tetracysteine-biarsenical labeling system or the new fluorescent protein for EM, MiniSOG), we determined the distribution of alpha-synuclein when over-expressed in primary neurons at supramolecular and cellular scales, in three dimensions (3D). We observed specific association of alpha-synuclein with a large and otherwise poorly characterized membranous organelle system of the presynaptic terminal, as well as with smaller vesicular structures within these boutons. Furthermore, alpha-synuclein was localized to multiple elements of the protein degradation pathway, including multivesicular bodies in the axons and lysosomes within neuronal cell bodies. Examination of synapses in brains of transgenic mice over-expressing human alpha-synuclein revealed alterations of the presynaptic endomembrane systems similar to our findings in cell culture. 3D electron tomographic analysis of enlarged presynaptic terminals in several brain areas revealed that these terminals were filled with membrane-bounded organelles, including tubulo-vesicular structures similar to what observed in vitro. We propose that alpha-synuclein over-expression is associated with hypertrophy of membrane systems of the presynaptic terminal previously shown to have a role in vesicle recycling. Our data support the conclusion that alpha- synuclein is involved in processes associated with the sorting, channeling, packaging and transport of synaptic material destined for degradation. PMID:23392688

  14. The Lyman α forest in a blazar-heated Universe

    Science.gov (United States)

    Puchwein, Ewald; Pfrommer, Christoph; Springel, Volker; Broderick, Avery E.; Chang, Philip

    2012-06-01

    It has been realized only recently that TeV emission from blazars can significantly heat the intergalactic medium (IGM) by pair-producing high-energy electrons and positrons, which in turn excite vigorous plasma instabilities, leading to a local dissipation of the pairs' kinetic energy. In this work, we use cosmological hydrodynamical simulations to model the impact of this blazar heating on the Lyman α forest at intermediate redshifts (z˜ 2-3). We find that blazar heating produces an inverted temperature-density relation in the IGM and naturally resolves many of the problems present in previous simulations of the forest that included photoionization heating alone. In particular, our simulations with blazar heating simultaneously reproduce the observed effective optical depth and temperature as a function of redshift, the observed probability distribution functions (PDFs) of the transmitted flux, and the observed flux power spectra, over the full redshift range 2 sum of thermally broadened individual lines, we find superb agreement with the observed lower cut-off of the linewidth distribution and abundances of neutral hydrogen column densities per unit redshift. Using the most recent constraints on the cosmic ultraviolet (UV) background, this excellent agreement with observations does not require rescaling the amplitude of the UV background - a procedure that was routinely used in the past to match the observed level of transmitted flux. We also show that our blazar-heated model matches the data better than standard simulations even when such a rescaling is allowed. This concordance between Lyman α data and simulation results, which are based on the most recent cosmological parameters, also suggests that the inclusion of blazar heating alleviates previous tensions on constraints for σ8 derived from Lyman α measurements and other cosmological data. Finally, we show that blazar heating dramatically alters the volume-weighted temperature PDF, implying an

  15. Mapping the Dynamics of a Giant Ly-alpha Halo at z=4.1 with MUSE: The Energetics of a Large Scale AGN-Driven Outflow around a Massive, High-Redshift Galaxy

    CERN Document Server

    Swinbank, Mark; Smail, Ian; De Breuck, Carlos; Bacon, Roland; Contini, Thierry; Richard, Johan; Rottgering, Huub; Urritia, Tanya; Venemans, Bram

    2015-01-01

    We present deep MUSE integral-field unit (IFU) spectroscopic observations of the giant (~150 x 80 kpc) Ly-alpha halo around the z=4.1 radio galaxy TNJ J1338-1942. This 9-hr observation maps the two-dimensional kinematics of the Ly-alpha emission across the halo. We identify two HI absorbers which are seen against the Ly-alpha emission, both of which cover the full 150 x 80 kpc extent of the halo and so have covering fractions ~1. The stronger and more blue-shifted absorber (dv~1200 km/s) has dynamics that mirror that of the underlying halo emission and we suggest that this high column material (n(HI) ~ 10^19.4 /cm^2), which is also seen in CIV absorption, represents an out-flowing shell that has been driven by the AGN (or star formation) within the galaxy. The weaker (n(HI)~10^14 /cm^2) and less blue shifted (dv~500 km/s) absorber most likely represents material in the cavity between the out-flowing shell and the Ly-alpha halo. We estimate that the mass in the shell must be of order 10^10 Msol -- a significan...

  16. Were progenitors of local L* galaxies Lyman-alpha emitters at high redshift?

    CERN Document Server

    Yajima, Hidenobu; Zhu, Qirong; Abel, Tom; Gronwall, Caryl; Ciardullo, Robin

    2011-01-01

    The Lya emission has been observed from galaxies over a redshift span z ~ 0 - 8.6. However, the link between high-redshift Lya emitters (LAEs) and local galaxies is largely unknown. Here, we investigate the Lya properties of progenitors of a local L^{*} galaxy by combining cosmological hydrodynamic simulations with three-dimensional radiative transfer calculations using the new ART^2 code. We find that the modeled galaxies are Lya bright in redshift z= 0 - 10. In particular, the Lya luminosities of some massive progenitors at z ~ 2 - 6 are close to the observed characteristic L_{Lya}^{*} of LAEs in that redshift range. Both Lya photon escape fraction and line equivalent width increase with redshift. The Lya escape fraction correlates with a number of physical properties of the galaxy, such as mass, SFR and metallicity. We find a "viewing-angle scatter" in which the photon escape depends strongly on the galaxy morphology and orientation. Moreover, we find that high-redshift LAEs show blue-shifted Lya line prof...

  17. LOOKING FOR LYMAN ALPHA EMITTING GALAXIES AT Z - 2.1

    OpenAIRE

    Guaita, Lucia

    2010-01-01

    Este proyecto de tesis de doctorado tuvo su inicio en Diciembre de 2007. En esta fecha se tomaron imágenes de la región del cielo llamada Extended Chandra Deep Field-South (ECDF-S) a través del filtro de banda angosta NB3727 y con el instrumento MO-SAIC II del telescopio de 4 metros de Cerro Tololo. El filtro está caracterizado por una longitud de onda central que corresponde a la línea Lγα con un desplazamiento hacia el rojo (redshift). z - 2.1. En este campo hemos descubierto una muestra de...

  18. The Heavy Element Enrichment of Lyman alpha Clouds in the Virgo Supercluster

    CERN Document Server

    Tripp, T M; Williger, G M; Heap, S R; Bowers, C W; Danks, A C; Davé, R; Green, R F; Gull, T R; Joseph, C L; Kaiser, M E; Lindler, D; Weymann, R J; Woodgate, B E

    2002-01-01

    Using high S/N STIS echelle spectra (FWHM=7 km/s) of 3C 273, we constrain the metallicities of two Lya clouds in the vicinity of the Virgo cluster. We detect C II, Si II, and Si III absorption lines in the Lya absorber at z = 0.00530. Previous observations with FUSE have revealed Ly beta - Ly theta lines at this redshift, thereby accurately constraining N(H I). We model the ionization of the gas and derive [C/H] = -1.2^{+0.3}_{-0.2}, [Si/C] = 0.2+/-0.1, and log n_{H} = -2.8+/-0.3. The model implies a small absorber thickness, ~70 pc, and thermal pressure p/k ~ 40 cm^{-3} K. It is most likely that the absorber is pressure confined by an external medium because gravitational confinement would require a very high ratio of dark matter to baryonic matter. Based on Milky Way sight lines in which carbon and silicon abundances have been reliably measured in the same interstellar cloud (including new measurements presented herein), we argue that the overabundance of Si relative to C is not due to dust depletion. Inste...

  19. The Local Lyman-$\\alpha$ Forest; 1, Distribution of HI Absorbers, Doppler Widths, and Baryon Content

    CERN Document Server

    Penton, S V; Stocke, J T; Penton, Steven V.; Stocke, John T.

    1999-01-01

    In Paper I of this series (astro-ph/9911117) we described observations of 15 extragalactic targets taken with the Hubble Space Telescope GHRS/G160M grating for studies of the low-z Lya forest. We reported the detection of 110 Lya absorbers at significance level >3 sigma in the redshift range z=0.002-0.069, over a total pathlength of 116,000 km/s. In this second paper, we evaluate the physical properties of these Lya absorbers and compare them to their high-z counterparts. The distribution of Doppler parameters is similar to that at high redshift, with mean b = 35.0 +- 16.6 km/s. The true Doppler parameter may be somewhat lower, owing to component blends and non-thermal velocities. The distribution of equivalent widths exhibits a significant break at W~133mA, with an increasing number of weak absorbers (10mA-100mA). Adopting a curve of growth with b = 25 +- 5km/s and applying a sensitivity correction as a function of equivalent width and wavelength, we derive the distribution in column density, Nh^{-1.80+-0.05...

  20. Metallicities and dust content of proximate damped Lyman alpha systems in the Sloan Digital Sky Survey

    CERN Document Server

    Ellison, Sara L; Mendel, J Trevor

    2010-01-01

    Composite spectra of 85 proximate absorbers (log N(HI)>20 and velocity difference between the absorption and emission redshift, dv6000 km/s, with further sub-samples to investigate the metal line dependence on N(HI) and QSO luminosity. Low (e.g. SiII and FeII) and high ionization (e.g. SiIV and CIV) species alike have equivalent widths (EWs) that are larger by factors of 1.5 -- 3 in the dv6000 km/s spectrum. The EWs show an even stronger dependence on dv if only the highest neutral hydrogen column density (log N(HI)>20.7) absorbers are considered. We conclude that PDLAs generally have higher metallicities than intervening absorbers, with the enhancement being a function of both dv and N(HI). It is also found that absorbers near QSOs with lower rest-frame UV luminosities have significantly stronger metal lines. We speculate that absorbers near to high luminosity QSOs may have had their star formation prematurely quenched. Finally, we search for the signature of dust reddening by the PDLAs, based on an analysis...

  1. The Composite Spectrum of BOSS Quasars Selected for Studies of the Lyman-alpha Forest

    CERN Document Server

    Harris, David W; Suzuki, Nao; Bautista, Julian E; Dawson, Kyle S; Vivek, M; Brownstein, Joel R; Ge, Jian; Hamann, Fred; Herbst, H; Jiang, Linhua; Moran, Sarah E; Myers, Adam D; Olmstead, Matthew D; Schneider, Donald P

    2016-01-01

    The Baryon Oscillation Spectroscopic Survey (BOSS) has collected more than 150,000 $2.1 \\leq z \\leq 3.5$ quasar spectra since 2009. Using this unprecedented sample, we create a composite spectrum in the rest-frame of 102,150 quasar spectra from 800 \\AA\\ to 3300 \\AA\\ at a signal-to-noise ratio close to 1000 per pixel ($\\Delta v$ of 69 km~s$^{-1}$). Included in this analysis is a correction to account for flux calibration residuals in the BOSS spectrophotometry. We determine the spectral index as a function of redshift of the full sample, warp the composite spectrum to match the median spectral index, and compare the resulting spectrum to SDSS photometry used in target selection. The quasar composite matches the color of the quasar population to within 0.02 magnitudes in $g-r$, 0.03 magnitudes in $r-i$, and 0.01 magnitudes in $i-z$ over the redshift range $2.2

  2. Constraints on neutrino masses from Lyman-alpha forest power spectrum with BOSS and XQ-100

    Science.gov (United States)

    Yèche, Christophe; Palanque-Delabrouille, Nathalie; Baur, Julien; du Mas des Bourboux, Hélion

    2017-06-01

    We present constraints on masses of active and sterile neutrinos in the context of the ΛCDMν and ΛWDM models, respectively. We use the one-dimensional Lyα-forest power spectrum from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS-III) measured by Palanque-Delabrouille et al. [1], and from the VLT/XSHOOTER legacy survey (XQ-100). In this paper, we present our own measurement of the publicly released XQ-100 quasar spectra, focusing in particular on an improved determination of the spectrograph resolution that allows us to push to smaller scales than the public release and reach k-modes of 0.070 s km-1. We compare the obtained 1D Lyα flux power spectrum to the one measured by Irsic et al. [2] to k-modes of 0.057 s km-1. Fitting Lyα data alone leads to cosmological parameters in excellent agreement with the values derived independently from Planck 2015 Cosmic Microwave Background (CMB) data. Combining BOSS and XQ-100 Lyα power spectra, we constrain the sum of neutrino masses to ∑ mν sources of systematic uncertainties. With the addition of CMB data, this bound is tightened to ∑ mν right-handed neutrinos. Combining the 1D Lyα-forest power spectrum measured by BOSS and XQ-100, we improve the two bounds to mX gtrsim 4.17 : keV and ms gtrsim 25.0 : keV (95% C.L.), slightly more constraining than what was achieved in Baur et al. 2015 [3] with BOSS data alone. The 3 σ bound shows a more significant improvement, increasing from mX gtrsim 2.74 : keV for BOSS alone to mX gtrsim 3.10 : keV for the combined BOSS+XQ-100 data set. Finally, we include in our analysis the first two redshift bins (z = 4.2 and z = 4.6) of the power spectrum measured by Viel et al. 2013 [4] with the high-resolution HIRES/MIKE spectrographs. The addition of HIRES/MIKE power spectrum allows us to further improve the two limits to mX gtrsim 4.65 : keV and ms gtrsim 28.8 : keV (95% C.L.).

  3. Ionizing radiation fluctuations and large-scale structure in the Lyman-alpha forest

    CERN Document Server

    Croft, R A C

    2003-01-01

    We investigate the large-scale inhomogeneities of the hydrogen ionizing radiation field in the Universe at redshift z=3. Using a raytracing algorithm, we simulate a model in which quasars are the dominant sources of radiation. We make use of large scale N-body simulations of a LambdaCDM universe, and include such effects as finite quasar lifetimes and output on the lightcone, which affects the shape of quasar light echoes. We create Lya forest spectra that would be generated in the presence of such a fluctuating radiation field, finding that the power spectrum of the Lya forest can be suppressed by as much as 15 % for modes with k=0.05-1 Mpc/h. This relatively small effect may have consequences for high precision measurements of the Lya power spectrum on larger scales than have yet been published. We also investigate another radiation field probe, the cross-correlation of quasar positions and the Lya forest. For both quasar lifetimes which we simulate (10^7 yr and 10^8 yr), we expect to see a strong decrease ...

  4. Lyman alpha emitting galaxies at 0.2 < z < 0.35 from GALEX spectroscopy

    CERN Document Server

    Deharveng, Jean-Michel; Barlow, Tom A; Peroux, Celine; Milliard, Bruno; Friedman, Peter G; Martin, D Christopher; Morrissey, Patrick; Schiminovich, David; Forster, Karl; Seibert, Mark; Wyder, Ted K; Bianchi, Luciana; Donas, Jose; Heckman, Timothy M; Lee, Young-Wook; Madore, Barry F; Neff, Susan G; Rich, R Michael; Szalay, A S; Welsh, Barry Y; Yi, Sukyoung K

    2008-01-01

    The GALEX (Galaxy Evolution Explorer) spectroscopic survey mode, with a resolution of about 8 A in the FUV (1350 - 1750 A) and about 20 A in the NUV (1950 - 2750 A) is used for a systematic search of Ly-a emitting galaxies at low redshift. This aims at filling a gap between high-redshift surveys and a small set of objects studied in detail in the nearby universe. A blind search of 7018 spectra extracted in 5 deep exposures (5.65 sq.deg) has resulted in 96 Ly-a emitting galaxy candidates in the FUV domain, after accounting for broad-line AGNs. The Ly-a EWs (equivalent width) are consistent with stellar population model predictions and show no trends as a function of UV color or UV luminosity, except a possible decrease in the most luminous that may be due to small-number statistics. Their distribution in EW is similar to that at z about 3 but their fraction among star-forming galaxies is smaller. Avoiding uncertain candidates, a sub-sample of 66 objects in the range 0.2 < z < 0.35 has been used to build ...

  5. The Lyman α signature of the first galaxies

    Science.gov (United States)

    Smith, Aaron; Safranek-Shrader, Chalence; Bromm, Volker; Milosavljević, Miloš

    2015-06-01

    We present the Cosmic Lyman α Transfer code, a massively parallel Monte Carlo radiative transfer code, to simulate Lyman α (Lyα) resonant scattering through neutral hydrogen as a probe of the first galaxies. We explore the interaction of centrally produced Lyα radiation with the host galactic environment. Lyα photons emitted from the luminous starburst region escape with characteristic features in the line profile depending on the density distribution, ionization structure, and bulk velocity fields. For example, anisotropic ionization exhibits a tall peak close to line centre with a skewed tail that drops off gradually. Idealized models of first galaxies explore the effect of mass, anisotropic H II regions, and radiation pressure driven winds on Lyα observables. We employ mesh refinement to resolve critical structures. We also post-process an ab initio cosmological simulation and examine images captured at various distances within the 1 Mpc3 comoving volume. Finally, we discuss the emergent spectra and surface brightness profiles of these objects in the context of high-z observations. The first galaxies will likely be observed through the red damping wing of the Lyα line. Observations will be biased towards galaxies with an intrinsic red peak located far from line centre that reside in extensive H II super bubbles, which allows Hubble flow to sufficiently redshift photons away from line centre and facilitate transmission through the intergalactic medium. Even with gravitational lensing to boost the luminosity this preliminary work indicates that Lyα emission from stellar clusters within haloes of Mvir Telescope.

  6. A new sodium channel alpha-subunit gene (Scn9a) from Schwann cells maps to the Scn1a, Scn2a, Scn3a cluster of mouse chromosome 2.

    Science.gov (United States)

    Beckers, M C; Ernst, E; Belcher, S; Howe, J; Levenson, R; Gros, P

    1996-08-15

    We have used a total of 27 AXB/BXA recombinant inbred mouse strains to determine the chromosomal location of a newly identified gene encoding an alpha-subunit isoform of the sodium channel from Schwann cells, Scn9a. Linkage analysis established that Scn9a mapped to the proximal segment of mouse chromosome 2. The segregation of restriction fragment length polymorphisms in 145 progeny from a Mus spretus x C57BL/6J backcross indicates that Scn9a is very tightly linked to Scn1a (gene encoding the type I sodium channel alpha-subunit of the brain) and forms part of a cluster of four Scna genes located on mouse chromosome 2.

  7. A new sodium channel {alpha}-subunit gene (Scn9a) from Schwann cells maps to the Scn1a, Scn2a, Scn3a cluster of mouse chromosome 2

    Energy Technology Data Exchange (ETDEWEB)

    Beckers, M.C.; Ernst, E.; Gros, P. [McGill Univ., Montreal (Canada)

    1996-08-15

    We have used a total of 27 AXB/BXA recombinant inbred mouse strains to determine the chromosomal location of a newly identified gene encoding an {alpha}-subunit isoform of the sodium channel from Schwann cells, Scn9a. Linkage analysis established that Scn9a mapped to the proximal segment of mouse chromosome 2. The segregation of restriction fragment length polymorphisms in 145 progeny from a Mus spretus x C57BL/6J backcross indicates that Scn9a is very tightly linked to Scn1a (gene encoding the type I sodium channel {alpha}-subunit of the brain) and forms part of a cluster of four Scna genes located on mouse chromosome 2. 17 refs., 1 fig., 3 tabs.

  8. Discovery of a very Lyman-α-luminous quasar at z = 6.62.

    Science.gov (United States)

    Koptelova, Ekaterina; Hwang, Chorng-Yuan; Yu, Po-Chieh; Chen, Wen-Ping; Guo, Jhen-Kuei

    2017-02-02

    Distant luminous quasars provide important information on the growth of the first supermassive black holes, their host galaxies and the epoch of reionization. The identification of quasars is usually performed through detection of their Lyman-α line redshifted to 0.9 microns at z > 6.5. Here, we report the discovery of a very Lyman-α luminous quasar, PSO J006.1240 + 39.2219 at redshift z = 6.618, selected based on its red colour and multi-epoch detection of the Lyman-α emission in a single near-infrared band. The Lyman-α line luminosity of PSO J006.1240 + 39.2219 is unusually high and estimated to be 0.8 × 10(12) Solar luminosities (about 3% of the total quasar luminosity). The Lyman-α emission of PSO J006.1240 + 39.2219 shows fast variability on timescales of days in the quasar rest frame, which has never been detected in any of the known high-redshift quasars. The high luminosity of the Lyman-α line, its narrow width and fast variability resemble properties of local Narrow-Line Seyfert 1 galaxies which suggests that the quasar is likely at the active phase of the black hole growth accreting close or even beyond the Eddington limit.

  9. Discovery of a very Lyman-α-luminous quasar at z = 6.62

    Science.gov (United States)

    Koptelova, Ekaterina; Hwang, Chorng-Yuan; Yu, Po-Chieh; Chen, Wen-Ping; Guo, Jhen-Kuei

    2017-01-01

    Distant luminous quasars provide important information on the growth of the first supermassive black holes, their host galaxies and the epoch of reionization. The identification of quasars is usually performed through detection of their Lyman-α line redshifted to 0.9 microns at z > 6.5. Here, we report the discovery of a very Lyman-α luminous quasar, PSO J006.1240 + 39.2219 at redshift z = 6.618, selected based on its red colour and multi-epoch detection of the Lyman-α emission in a single near-infrared band. The Lyman-α line luminosity of PSO J006.1240 + 39.2219 is unusually high and estimated to be 0.8 × 1012 Solar luminosities (about 3% of the total quasar luminosity). The Lyman-α emission of PSO J006.1240 + 39.2219 shows fast variability on timescales of days in the quasar rest frame, which has never been detected in any of the known high-redshift quasars. The high luminosity of the Lyman-α line, its narrow width and fast variability resemble properties of local Narrow-Line Seyfert 1 galaxies which suggests that the quasar is likely at the active phase of the black hole growth accreting close or even beyond the Eddington limit. PMID:28150701

  10. Predominantly Low Metallicities Measured in a Stratified Sample of Lyman Limit Systems at z=3.7

    CERN Document Server

    Glidden, Ana; Cooksey, Kathy L; Simcoe, Robert A; O'Meara, John M

    2016-01-01

    We analyzed metallicities for 33 z=3.4-4.2 absorption line systems with large neutral hydrogen column densities, drawn from a sample of H I-selected of Lyman limit systems (LLSs) identified in Sloan Digital Sky Survey (SDSS) quasar spectra, and stratified based on metal line features. We obtained higher-resolution spectra with the Keck Echellette Spectrograph and Imager (ESI), selecting targets according to our stratification scheme in an effort to fully sample the LLS population metallicity distribution. We established a plausible range of H I column densities and measured the metal column densities (or limits) for ions of carbon, silicon, and aluminum. With simulations, we found ionization-corrected metallicities or upper limits, when appropriate. Interestingly, our ionization models were better constrained with enhanced {\\alpha}-to-aluminum abundances, with a median abundance ratio of [{\\alpha}/Al]=0.3. Measured metallicities were generally low, ranging from [M/H]=-3 to -1.68, with even lower metallicities...

  11. AlphaSphere

    OpenAIRE

    Place, A.; Lacey, L.; Mitchell, T.

    2013-01-01

    The AlphaSphere is an electronic musical instrument featuring a series of tactile, pressure sensitive touch pads arranged in a spherical form. It is designed to offer a new playing style, while allowing for the expressive real-time modulation of sound available in electronic-based music. It is also designed to be programmable, enabling the flexibility to map a series of different notational arrangements to the pad-based interface.\\ud \\ud The AlphaSphere functions as an HID, MIDI and OSC devic...

  12. Lyman-tomography of cosmic infrared background fluctuations with Euclid: probing emissions and baryonic acoustic oscillations at z>10

    CERN Document Server

    Kashlinsky, A; Atrio-Barandela, F; Helgason, K

    2015-01-01

    The Euclid space mission, designed to probe evolution of the Dark Energy, will map a large area of the sky at three adjacent near-IR filters, Y, J and H. This coverage will also enable mapping source-subtracted cosmic infrared background (CIB) fluctuations with unprecedented accuracy on sub-degree angular scales. Here we propose methodology, using the Lyman-break tomography applied to the Euclid-based CIB maps, to accurately isolate the history of CIB emissions as a function of redshift from 10 ~ 400 sq deg. The method can isolate the CIB spatial spectrum by z to sub-percent statistical accuracy. We illustrate this with a specific model of CIB production at high z normalized to reproduce the measured Spitzer-based CIB fluctuation. We show that even if the latter contain only a small component from high-z sources, the amplitude of that component can be accurately isolated with the methodology proposed here and the BAO signatures at z>~ 10 are recovered well from the CIB fluctuation spatial spectrum. Probing th...

  13. Extended Ly$\\alpha$ emission around quasars with eclipsing damped Ly$\\alpha$ systems

    CERN Document Server

    Fathivavsari, Hassan; Noterdaeme, Pasquier; Pâris, Isabelle; Finley, Hayley; López, Sebastian; Srianand, Raghunathan

    2016-01-01

    We present spectroscopic observations of six high redshift ($z_{\\rm em}$ $>$ 2) quasars, which have been selected for their Lyman $\\alpha$ (Ly$\\alpha$) emission region being only partially covered by a strong proximate ($z_{\\rm abs}$ $\\sim$ $z_{\\rm em}$) coronagraphic damped Ly$\\alpha$ system (DLA). We detected spatially extended Ly$\\alpha$ emission envelopes surrounding these six quasars, with projected spatial extent in the range 26 $\\le$ $d_{\\rm Ly\\alpha}$ $\\le$ 51 kpc. No correlation is found between the quasar ionizing luminosity and the Ly$\\alpha$ luminosity of their extended envelopes. This could be related to the limited covering factor of the extended gas and/or due to the AGN being obscured in other directions than towards the observer. Indeed, we find a strong correlation between the luminosity of the envelope and its spatial extent, which suggests that the envelopes are probably ionized by the AGN. The metallicity of the coronagraphic DLAs is low and varies in the range $-$1.75 $<$ [Si/H] $<...

  14. The Ly$\\alpha$ emission from high-$z$ galaxies hosting strong Damped Ly$\\alpha$ systems

    CERN Document Server

    Joshi, Ravi; Noterdaeme, Pasquier; Petitjean, Patrick

    2016-01-01

    We study the average Ly$\\alpha$ emission associated with high-$z$ strong (log $N$(H I) $\\ge$ 21) damped Ly$\\alpha$ systems (DLAs). We report Ly$\\alpha$ luminosities ($L_{\\rm Ly\\alpha}$) for the full as well as various sub-samples based on $N$(H I), $z$, $(r-i)$ colours of QSOs and rest equivalent width of Si II$\\lambda$1526 line (i.e., $W_{1526}$). For the full sample, we find $L_{\\rm Ly\\alpha}$$< 10^{41} (3\\sigma)\\ \\rm erg\\ s^{-1}$ with a $2.8\\sigma$ level detection of Ly$\\alpha$ emission in the red part of the DLA trough. The $L_{\\rm Ly\\alpha}$ is found to be higher for systems with higher $W_{1526}$ with its peak, detected at $\\geq 3\\sigma$, redshifted by about 300-400 $\\rm km\\ s^{-1}$ with respect to the systemic absorption redshift, as seen in Lyman Break Galaxies (LBGs) and Ly$\\alpha$ emitters. A clear signature of a double-hump Ly$\\alpha$ profile is seen when we consider $W_{1526} \\ge 0.4$ \\AA\\ and $(r-i) < 0.05$. Based on the known correlation between metallicity and $W_{1526}$, we interpret our...

  15. Lyman Break Galaxies at z~5 Luminosity Function

    CERN Document Server

    Iwata, I; Tamura, N; Ando, M; Wada, S; Watanabe, C; Akiyama, M; Aoki, K

    2003-01-01

    (abridged) We present results of a search for Lyman break galaxies (LBGs) at z ~ 5 in a 618 square-arcmin field including the HDF-N taken by Subaru Prime Focus Camera. Utilizing the published redshift data of the HDF-N and its flanking fields, the color selection criteria are chosen so that LBGs are picked out most efficiently and least contaminated by foreground objects. The numbers of LBG candidates detected are 310 in 23.0 < I_c < 25.5. The rest-frame UV luminosity function(LF) of LBGs at z ~ 5 is derived statistically. The fraction of contamination is estimated to be ~50% in the faintest magnitude range. The completeness of the survey is ~80% at the bright part of the sample, and ~20% in the faintest magnitude range (25.0 < I_c <= 25.5). The LF of LBG candidates at z ~ 5 does not show a significant difference from those at z ~ 3 and 4, though there might be a slight decrease in the fainter part. The UV luminosity density within the observational limit is 0.56 - 0.69 times smaller than that obt...

  16. Project Lyman: Quantifying 11 Gyrs of Metagalactic Ionizing Background Evolution

    CERN Document Server

    McCandliss, Stephan R; Bergvall, Nils; Bianchi, Luciana; Bridge, Carrie; Bogosavljevic, Milan; Cohen, Seth H; Deharveng, Jean-Michel; Dixon, W Van Dyke; Ferguson, Harry; Friedman, Peter; Hayes, Matthew; Howk, J Christopher; Inoue, Akio; Iwata, Ikuru; Kaiser, Mary Elizabeth; Kriss, Gerard; Kruk, Jeffrey; Kutyrev, Alexander S; Leitherer, Claus; Meurer, Gerhardt R; Prochaska, Jason X; Sonneborn, George; Stiavelli, Massimo; Teplitz, Harry I; Windhorst, Rogier A

    2012-01-01

    The timing and duration of the reionization epoch is crucial to the emergence and evolution of structure in the universe. The relative roles that star-forming galaxies, active galactic nuclei and quasars play in contributing to the metagalactic ionizing background across cosmic time remains uncertain. Deep quasar counts provide insights into their role, but the potentially crucial contribution from star-formation is highly uncertain due to our poor understanding of the processes that allow ionizing radiation to escape into the intergalactic medium (IGM). The fraction of ionizing photons that escape from star-forming galaxies is a fundamental free parameter used in models to "fine-tune" the timing and duration of the reionization epoch that occurred somewhere between 13.4 and 12.7 Gyrs ago (redshifts between 12 > z > 6). However, direct observation of Lyman continuum (LyC) photons emitted below the rest frame \\ion{H}{1} ionization edge at 912 \\AA\\ is increasingly improbable at redshifts z > 3, due to the stead...

  17. Dust properties of Lyman break galaxies in cosmological simulations

    CERN Document Server

    Yajima, Hidenobu; Thompson, Robert; Choi, Jun-Hwan

    2013-01-01

    Recent observations have indicated the existence of dust in high-redshift galaxies, however, the dust properties in them are still unknown. Here we present theoretical constraints on dust properties in Lyman break galaxies (LBGs) at z=3 by post-processing a cosmological smoothed particle hydrodynamics simulation with radiative transfer calculations. We calculate the dust extinction in 2800 dark matter halos using the metallicity information of individual gas particles in our simulation. We use only bright galaxies with rest-frame UV magnitude M_1700 < -20 mag, and study the dust size, dust-to-metal mass ratio, and dust composition. From the comparison of calculated color excess between B and V-band (i.e., E(B-V)) and the observations, we constrain the typical dust size, and show that the best-fitting dust grain size is ~ 0.05 micron, which is consistent with the results of theoretical dust models for Type-II supernova. Our simulation with the dust extinction effect can naturally reproduce the observed rest...

  18. A Lyman Break Galaxy Candidate at z~9

    CERN Document Server

    Henry, Alaina L; Colbert, James W; Siana, Brian; Teplitz, Harry I; McCarthy, Patrick

    2008-01-01

    We report the discovery of a z~9 Lyman Break Galaxy (LBG) candidate, selected from the NICMOS Parallel Imaging Survey as a J-dropout with J110 - H160 = 1.7. Spitzer/IRAC photometry reveals that the galaxy has a blue H160 - 3.6 um color, and a spectral break between 3.6 and 4.5 um. We interpret this break as the Balmer break, and derive a best-fit photometric redshift of z~9. We use Monte Carlo simulations to test the significance of this photometric redshift, and show a 96% probability of z>7. We estimate a lower limit to the comoving number density of such galaxies at z~9 of phi > 3.8 x 10^{-6} Mpc^{-3}. If the high redshift of this galaxy is confirmed, this will indicate that the luminous end of the rest-frame UV luminosity function has not evolved substantially from z~ 9 to z~3. Still, some small degeneracy remains between this z~9 model and models at z~2-3; deep optical imaging (reaching I ~ 29 AB) can rule out the lower-z models.

  19. The Stellar Populations and Evolution of Lyman Break Galaxies

    CERN Document Server

    Papovich, C; Ferguson, H C; Papovich, Casey; Dickinson, Mark; Ferguson, Henry C.

    2001-01-01

    Using deep near-IR and optical observations of the HDF-N from the HST NICMOS and WFPC2 and from the ground, we examine the spectral energy distributions (SEDs) of Lyman break galaxies (LBGs) at 2.0 < z < 3.5. The UV-to-optical rest-frame SEDs of the galaxies are much bluer than those of present-day spiral and elliptical galaxies, and are generally similar to those of local starburst galaxies with modest amounts of reddening. We use stellar population synthesis models to study the properties of the stars that dominate the light from LBGs. Under the assumption that the star-formation rate is continuous or decreasing with time, the best-fitting models provide a lower bound on the LBG mass estimates. LBGs with ``L*'' UV luminosities are estimated to have minimum stellar masses ~ 10^10 solar masses, or roughly 1/10th that of a present-day L* galaxy. By considering the effects of a second component of maximally-old stars, we set an upper bound on the stellar masses that is ~ 3-8 times the minimum estimate. We...

  20. Lyman-Werner UV escape fractions from primordial haloes

    Science.gov (United States)

    Schauer, Anna T. P.; Whalen, Daniel J.; Glover, Simon C. O.; Klessen, Ralf S.

    2015-12-01

    Population III (Pop III) stars can regulate star formation in the primordial Universe in several ways. They can ionize nearby haloes, and even if their ionizing photons are trapped by their own haloes, their Lyman-Werner (LW) photons can still escape and destroy H2 in other haloes, preventing them from cooling and forming stars. LW escape fractions are thus a key parameter in cosmological simulations of early reionization and star formation but have not yet been parametrized for realistic haloes by halo or stellar mass. To do so, we perform radiation hydrodynamical simulations of LW UV escape from 9-120 M⊙ Pop III stars in 105-107 M⊙ haloes with ZEUS-MP. We find that photons in the LW lines (i.e. those responsible for destroying H2 in nearby systems) have escape fractions ranging from 0 to 85 per cent. No LW photons escape the most massive halo in our sample, even from the most massive star. Escape fractions for photons elsewhere in the 11.18-13.6 eV energy range, which can be redshifted into the LW lines at cosmological distances, are generally much higher, being above 60 per cent for all but the least massive stars in the most massive haloes. We find that shielding of H2 by neutral hydrogen, which has been neglected in most studies to date, produces escape fractions that are up to a factor of 3 smaller than those predicted by H2 self-shielding alone.

  1. The z ~ 4 Lyman Break Galaxies: Colors and Theoretical Predictions

    CERN Document Server

    Idzi, R; Papovich, C; Ferguson, H C; Giavalisco, M; Kretchmer, C; Lotz, J; Idzi, Rafal; Somerville, Rachel; Papovich, Casey; Ferguson, Henry C.; Giavalisco, Mauro; Kretchmer, Claudia; Lotz, Jennifer

    2004-01-01

    We investigate several fundamental properties of z ~ 4 Lyman-break galaxies by comparing observations with the predictions of a semi-analytic model based on the Cold Dark Matter theory of hierarchical structure formation. We use a sample of B_{435}-dropouts from the Great Observatories Origins Deep Survey, and complement the ACS optical B_{435}, V_{606}, i_{775}, and z_{850} data with the VLT ISAAC J, H, and K_{s} observations. We extract B_{435}-dropouts from our semi-analytic mock catalog using the same color criteria and magnitude limits that were applied to the observed sample. We find that the i_{775} - K_{s} colors of the model-derived and observed B_{435}-dropouts are in good agreement. However, we find that the i_{775}-z_{850} colors differ significantly, indicating perhaps that either too little dust or an incorrect extinction curve have been used. Motivated by the reasonably good agreement between the model and observed data we present predictions for the stellar masses, star formation rates, and ag...

  2. Lyman-Werner UV Escape Fractions from Primordial Halos

    CERN Document Server

    Schauer, Anna T P; Glover, Simon C O; Klessen, Ralf S

    2015-01-01

    Population III stars can regulate star formation in the primordial Universe in several ways. They can ionize nearby halos, and even if their ionizing photons are trapped by their own halos, their Lyman-Werner (LW) photons can still escape and destroy H$_2$ in other halos, preventing them from cooling and forming stars. LW escape fractions are thus a key parameter in cosmological simulations of early reionization and star formation but have not yet been parametrized for realistic halos by halo or stellar mass. To do so, we perform radiation hydrodynamical simulations of LW UV escape from 9--120 M$_{\\odot}$ Pop III stars in $10^5$ to $10^7$ M$_{\\odot}$ halos with ZEUS-MP. We find that photons in the LW lines (i.e. those responsible for destroying H$_{2}$ in nearby systems) have escape fractions ranging from 0% to 85%. No LW photons escape the most massive halo in our sample, even from the most massive star. Escape fractions for photons elsewhere in the 11.18--13.6~eV energy range, which can be redshifted into t...

  3. Lyman continuum leaking AGN in the SSA22 field

    Science.gov (United States)

    Micheva, Genoveva; Iwata, Ikuru; Inoue, Akio K.

    2017-02-01

    Subaru/SuprimeCam narrow-band photometry of the SSA22 field reveals the presence of four Lyman continuum (LyC) candidates among a sample of 14 active galactic nuclei (AGNs). Two show offsets and likely have stellar LyCin nature or are foreground contaminants. The remaining two LyC candidates are type I AGN. We argue that the average LyC escape fraction of high-redshift, low-luminosity AGN is not likely to be unity, as often assumed in the literature. From direct measurement we obtain the average LyC-to-UV flux density ratio and ionizing emissivity for a number of AGN classes and find it at least a factor of 2 lower than values obtained assuming fesc = 1. Comparing to recent Ly α forest measurements, AGNs at redshift z ˜ 3 make up at most ˜12 per cent and as little as ˜5 per cent of the total ionizing budget. Our results suggest that AGNs are unlikely to dominate the ionization budget of the Universe at high redshifts.

  4. Alpha Blockers

    Science.gov (United States)

    ... positive side, alpha blockers might decrease low-density lipoprotein (LDL) cholesterol (the "bad" cholesterol). Alpha blockers can ... PreventionTreatmentofHighBloodPressure/Types-of-Blood-Pressure-Medications_UCM_303247_Article.jsp. Accessed June 4, 2016. Kaplan NM, et ...

  5. The genetic differences with whole genome linkage disequilibrium mapping between responder and non-responder in interferon-alpha and ribavirin combined therapy for chronic hepatitis C patients.

    Science.gov (United States)

    Chen, P-J; Hwang, Y; Lin, C G-J; Wu, Y-J; Wu, L S-H

    2008-04-01

    Interferon-alpha and ribavirin combined therapy has been a mainstream treatment for hepatitis C infection. The efficacy of this combined treatment is around 30% to 60%, and the factors affecting the responsiveness are still poorly defined. Our study is intended to investigate the genetic differences between responder and non-responder patients. The genome-wide linkage disequilibrium screening for loci associated with genetic difference between two patient groups was conducted by using 382 autosomal short tandem repeat (STR) markers involving 92 patients. We have identified 19 STR markers displaying different allele frequencies between the two patient groups. In addition, based on their genomic location and biological function, we selected the CD81 and IL15 genes to perform single nucleotide polymorphism genotyping. In conclusion, this study may provide a new approach for identifying the associated polymorphisms and the susceptible loci for interferon-alpha and ribavirin combined therapy in patients with chronic hepatitis C.

  6. Direct Detection of Lyman Continuum Escape from Local Starburst Galaxies with the Cosmic Origins Spectrograph

    CERN Document Server

    Leitherer, Claus; Lee, Janice C; Oey, M S

    2016-01-01

    We report on the detection of Lyman continuum radiation in two nearby starburst galaxies. Tol 0440-381, Tol 1247-232 and Mrk 54 were observed with the Cosmic Origins Spectrograph onboard the Hubble Space Telescopes. The three galaxies have radial velocities of ~13,000 km/s, permitting a ~35 A window on the restframe Lyman continuum shortward of the Milky Way Lyman edge at 912 A. The chosen instrument configuration using the G140L grating covers the spectral range from 912 to 2,000 {\\AA}. We developed a dedicated background subtraction method to account for temporal and spatial background variations of the detector, which is crucial at the low flux levels around 912 A. This modified pipeline allowed us to significantly improve the statistical and systematic detector noise and will be made available to the community. We detect Lyman continuum in all three galaxies. However, we conservatively interpret the emission in Tol 0440-381 as an upper limit due to possible contamination by geocoronal Lyman series lines. ...

  7. Lyman α emission from the first galaxies : Signatures of accretion and infall in the presence of line trapping

    NARCIS (Netherlands)

    Latif, M.A.; Schleicher, Dominik R. G.; Spaans, Maarten; Zaroubi, S.

    2011-01-01

    The formation of the first galaxies is accompanied by large accretion flows and virialization shocks, during which the gas is shock heated to temperatures of ˜104 K, leading to potentially strong fluxes in the Lyman α line. Indeed, a number of Lyman α blobs have been detected at high redshift. In th

  8. Lyman α emission from the first galaxies: signatures of accretion and infall in the presence of line trapping

    NARCIS (Netherlands)

    Latif, M. A.; Schleicher, Dominik R. G.; Spaans, M.; Zaroubi, S.

    2011-01-01

    The formation of the first galaxies is accompanied by large accretion flows and virialization shocks, during which the gas is shock heated to temperatures of ˜104 K, leading to potentially strong fluxes in the Lyman α line. Indeed, a number of Lyman α blobs have been detected at high redshift. In th

  9. A possible solution to the Lyman/Balmer line problem in hot DA white dwarfs

    CERN Document Server

    Preval, S P; Badnell, N R; Holberg, J B; Hubeny, I

    2014-01-01

    Arguably, the best method for determining the effective temperature ($T_{\\mathrm{eff}}$) and surface gravity (log $g$) of a DA white dwarf is by fitting the Hydrogen Lyman and Balmer absorption features. However, as has been shown for white dwarfs with $T_{\\mathrm{eff}}$>50,000K, the calculated value from the Lyman and Balmer lines are discrepant, which worsens with increasing temperature. Many different solutions have been suggested, ranging from the input physics used to calculate the models, to interstellar reddening. We will focus on the former, and consider three variables. The first is the atomic data used, namely the number of transitions included in line blanketing treatments and the photoionization cross sections. The second is the stark broadening treatment used to synthesise the Lyman and Balmer line profiles, namely the calculations performed by Lemke (1997) and Tremblay & Bergeron (2009). Finally, the third is the atmospheric content. The model grids are calculated with a pure H composition, ...

  10. Lyman α radiation hydrodynamics of galactic winds before cosmic reionization

    Science.gov (United States)

    Smith, Aaron; Bromm, Volker; Loeb, Abraham

    2017-01-01

    The dynamical impact of Lyman α (Lyα) radiation pressure on galaxy formation depends on the rate and duration of momentum transfer between Lyα photons and neutral hydrogen gas. Although photon trapping has the potential to multiply the effective force, ionizing radiation from stellar sources may relieve the Lyα pressure before appreciably affecting the kinematics of the host galaxy or efficiently coupling Lyα photons to the outflow. We present self-consistent Lyα radiation-hydrodynamics simulations of high-z galaxy environments by coupling the Cosmic Lyα Transfer code (COLT) with spherically symmetric Lagrangian frame hydrodynamics. The accurate but computationally expensive Monte Carlo radiative transfer calculations are feasible under the one-dimensional approximation. The initial starburst drives an expanding shell of gas from the centre and in certain cases, Lyα feedback significantly enhances the shell velocity. Radiative feedback alone is capable of ejecting baryons into the intergalactic medium (IGM) for protogalaxies with a virial mass of Mvir ≲ 108 M⊙. We compare the Lyα signatures of Population III stars with 105 K blackbody emission to that of direct collapse black holes with a non-thermal Compton-thick spectrum and find substantial differences if the Lyα spectra are shaped by gas pushed by Lyα radiation-driven winds. For both sources, the flux emerging from the galaxy is reprocessed by the IGM such that the observed Lyα luminosity is reduced significantly and the time-averaged velocity offset of the Lyα peak is shifted redward.

  11. Alpha fetoprotein

    Science.gov (United States)

    Fetal alpha globulin; AFP ... Greater than normal levels of AFP may be due to: Cancer in testes , ovaries, biliary (liver secretion) tract, stomach, or pancreas Cirrhosis of the liver Liver cancer ...

  12. HST/COS Spectra of DF Tau and V4046 SGR: First Detection of Molecular Hydrogen Absorption Against the Ly$\\alpha$ Emission Line

    CERN Document Server

    Yang, Hao; France, Kevin

    2011-01-01

    We report the first detection of molecular hydrogen (H$_{2}$) absorption in the Lyman-$\\alpha$ emission line profiles of two classical T Tauri stars (CTTSs), DF Tau and V4046 Sgr, observed by \\emph{HST}/COS. This absorption is the energy source for many of the Lyman-band H$_{2}$ fluorescent lines commonly seen in the far-ultraviolet spectra of CTTSs. We find that the absorbed energy in the H$_{2}$ pumping transitions from a portion of the Lyman-$\\alpha$ line significantly differ from the amount of energy in the resulting fluorescent emission. By assuming additional absorption in the H I Lyman-$\\alpha$ profile along our light of sight, we can correct the H$_{2}$ absorption/emission ratios so that they are close to unity. The required H I absorption for DF Tau is at a velocity close to the radial velocity of the star, consistent with H I absorption in the edge-on disk and interstellar medium. For V4046 Sgr, a nearly face-on system, the required absorption is between +100 km/s and +290 km/s, most likely resultin...

  13. Strong Ly$\\alpha$ Emission in the Proximate Damped Ly$\\alpha$ Absorption Trough toward the Quasar SDSS J095253.83$+$011422.0

    CERN Document Server

    Jiang, Peng; Pan, Xiang; Jiang, Ning; Shu, Xinwen; Wang, Huiyuan; Gu, Qiusheng; Li, Zhenzhen; Wu, Maochun; Shi, Xiheng; Ji, Tuo; Tian, Qiguo; Zhang, Shaohua

    2016-01-01

    SDSS J095253.83$+$011422.0 (SDSS J0952$+$0114) was reported by Hall et al. (2004) as an exotic quasar at $z_{em}=3.020$. In contrast to prominent broad metal--line emissions with FWHM$\\sim9000$~km~s$^{-1}$, only a narrow Ly$\\alpha$ emission line is present with FWHM$\\sim$1000~km~s$^{-1}$. The absence of broad Ly$\\alpha$ emission line has been a mystery for more than a decade. In this paper, we demonstrate that this is due to dark Proximate Damped Ly$\\alpha$ Absorption (PDLA) at $z_{abs}=3.010$ by identifying associated Lyman absorption line series from the damped Ly$\\beta$ up to Ly9, as well as the Lyman limit absorption edge. The PDLA cloud has a column density of $\\log N_{\\rm H\\,I}({\\rm cm}^{-2})=21.8\\pm0.2$, a metallicity of [Zn/H]$>-1.0$, and a spatial extent exceeding the Narrow Emission Line Region (NELR) of the quasar. With a luminosity of $L_{{\\rm Ly}\\alpha}\\sim10^{45}$~erg~s$^{-1}$, the residual Ly$\\alpha$ emission superposed on the PDLA trough is of two orders of magnitude stronger than previous rep...

  14. The Lyman continuum escape and ISM properties in Tololo 1247-232 - new insights from HST and VLA★

    Science.gov (United States)

    Puschnig, J.; Hayes, M.; Östlin, G.; Rivera-Thorsen, T. E.; Melinder, J.; Cannon, J. M.; Menacho, V.; Zackrisson, E.; Bergvall, N.; Leitet, E.

    2017-08-01

    Low- and intermediate-mass galaxies are widely discussed as cause of reionization at redshift z ∼ 10-6. However, observational proof of galaxies that are leaking ionizing radiation (Lyman continuum; LyC) is a currently ongoing challenge and the list of LyC emitting candidates is still short. Tololo 1247-232 is among those very few galaxies with recently reported leakage. We performed intermediate resolution ultraviolet spectroscopy with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope and confirm ionizing radiation emerging from Tololo 1247-232. Adopting an improved data reduction procedure, we find that LyC escapes from the central stellar clusters, with an escape fraction of 1.5 ± 0.5 per cent only, i.e. the lowest value reported for the galaxy so far. We further make use of far-ultraviolet absorption lines of Si ii and Si iv as a probe of the neutral and ionized interstellar medium (ISM). We find that most of the ISM gas is ionized, likely facilitating LyC escape from density bounded regions. Neutral gas covering as a function of line-of-sight velocity is derived using the apparent optical depth method. The ISM is found to be sufficiently clumpy, supporting the direct escape of LyC photons. We further report on broad-band UV and optical continuum imaging as well as narrow-band imaging of Lyα, Hα and Hβ. Using stellar population synthesis, an Lyα escape fraction of 8 per cent was derived. We also performed Very Large Array 21cm imaging. The hydrogen hyperfine transition was not detected, but a deep upper limit atomic gas mass of ≲109 M⊙ could be derived. The upper limit gas fraction defined as M_{H I}/M_* is only 20 per cent. Evidence is found that the H i gas halo is relatively small compared to the Lyman Alpha Reference Sample (Hayes et al. 2013, 2014; Östlin et al. 2014).

  15. Lyman-α forest constraints on decaying dark matter

    Science.gov (United States)

    Wang, Mei-Yu; Croft, Rupert A. C.; Peter, Annika H. G.; Zentner, Andrew R.; Purcell, Chris W.

    2013-12-01

    We present an analysis of high-resolution N-body simulations of decaying dark matter cosmologies focusing on the statistical properties of the transmitted Lyman-α (Lyα) forest flux in the high-redshift intergalactic medium (IGM). In this type of model a dark matter particle decays into a slightly less massive stable dark matter daughter particle and a comparably light particle. The small mass splitting provides a nonrelativistic kick velocity Vk=cΔM/M to the daughter particle resulting in free-streaming and subsequent damping of small-scale density fluctuations. Current Lyα forest power spectrum measurements probe comoving scales up to ˜2-3h-1Mpc at redshifts z˜2-4, providing one of the most robust ways to probe cosmological density fluctuations on relatively small scales. The suppression of structure growth due to the free-streaming of dark matter daughter particles also has a significant impact on the neutral hydrogen cloud distribution, which traces the underlying dark matter distribution well at high redshift. We exploit Lyα forest power spectrum measurements to constrain the amount of free-streaming of dark matter in such models and thereby place limits on decaying dark matter based only on the dynamics of cosmological perturbations without any assumptions about the interactions of the decay products. We use a suite of dark-matter-only simulations together with the fluctuating Gunn-Peterson approximation to derive the Lyα flux distribution. We argue that this approach should be sufficient for our main purpose, which is to demonstrate the power of the Lyα forest to constrain decaying dark matter models. We find that Sloan Digital Sky Survey 1D Lyα forest power spectrum data place a lifetime-dependent upper limit Vk≲30-70km/s for decay lifetimes ≲10Gyr. This is the most stringent model-independent bound on invisible dark matter decays with small mass splittings. For larger mass splittings (large Vk), Lyα forest data restrict the dark matter

  16. SPECTROSCOPIC CONFIRMATION OF z {approx} 7 LYMAN BREAK GALAXIES: PROBING THE EARLIEST GALAXIES AND THE EPOCH OF REIONIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Pentericci, L.; Fontana, A.; Castellano, M.; Grazian, A.; Boutsia, K.; Giallongo, E.; Maiolino, R.; Paris, D.; Santini, P. [INAF Osservatorio Astronomico di Roma, Via Frascati 33,00040 Monteporzio (Italy); Vanzella, E.; Cristiani, S. [INAF Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34131 Trieste (Italy); Dijkstra, M. [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching (Germany); Dickinson, M. [National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726 (United States); Giavalisco, M. [Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003 (United States); Moorwood, A., E-mail: laura.pentericci@oa-roma.inaf.it [European Southern Observatory, Karl-Schwarzschild Strasse, 85748 Garching (Germany)

    2011-12-20

    We present the final results from our ultra-deep spectroscopic campaign with FORS2 at the ESO Very Large Telescope (VLT) for the confirmation of z {approx_equal} 7 'z-band dropout' candidates selected from our VLT/Hawk-I imaging survey over three independent fields. In particular, we report on two newly discovered galaxies at redshift {approx}6.7 in the New Technology Telescope Deep Field. Both galaxies show an Ly{alpha} emission line with rest-frame equivalent widths (EWs) of the order of 15-20 A and luminosities of (2-4) Multiplication-Sign 10{sup 42} erg s{sup -1}. We also present the results of ultra-deep observations of a sample of i-dropout galaxies, from which we set a solid upper limit on the fraction of interlopers. Out of the 20 z-dropouts observed we confirm 5 galaxies at 6.6 < z < 7.1. This is systematically below the expectations drawn on the basis of lower redshift observations: in particular, there is a significant lack of objects with intermediate Ly{alpha} EWs (between 20 and 55 A). We conclude that the observed trend for the rising fraction of Ly{alpha} emission in Lyman break galaxies from z {approx} 3 to z {approx} 6 is most probably reversed from z {approx} 6 to z {approx} 7. Explaining the observed rapid change in the Ly{alpha} emitter fraction among the dropout population with reionization requires a fast evolution of the neutral fraction of hydrogen in the universe. Assuming that the universe is completely ionized at z = 6 and adopting a set of semi-analytical models, we find that our data require a change of the neutral hydrogen fraction of the order of {Delta}{chi}{sub H{sub i}}{approx}0.6 in a time {Delta}z {approx} 1, provided that the escape fraction does not increase dramatically over the same redshift interval.

  17. Discovery of a faint, star-forming, multiply lensed, Lyman-α blob

    NARCIS (Netherlands)

    Caminha, G. B.; Karman, W.; Rosati, P.; Caputi, K. I.; Arrigoni Battaia, F.; Balestra, I.; Grillo, C.; Mercurio, A.; Nonino, M.; Vanzella, E.

    2016-01-01

    We report the discovery of a multiply lensed Lyman-α blob (LAB) behind the galaxy cluster AS1063 using the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT). The background source is at z = 3.117 and is intrinsically faint compared to almost all previously reported LABs. We

  18. $\\alpha_s$ review (2016)

    CERN Document Server

    d'Enterria, David

    2016-01-01

    The current world-average of the strong coupling at the Z pole mass, $\\alpha_s(m^2_{Z}) = 0.1181 \\pm 0.0013$, is obtained from a comparison of perturbative QCD calculations computed, at least, at next-to-next-to-leading-order accuracy, to a set of 6 groups of experimental observables: (i) lattice QCD "data", (ii) $\\tau$ hadronic decays, (iii) proton structure functions, (iv) event shapes and jet rates in $e^+e^-$ collisions, (v) Z boson hadronic decays, and (vi) top-quark cross sections in p-p collisions. In addition, at least 8 other $\\alpha_s$ extractions, usually with a lower level of theoretical and/or experimental precision today, have been proposed: pion, $\\Upsilon$, W hadronic decays; soft and hard fragmentation functions; jets cross sections in pp, e-p and $\\gamma$-p collisions; and photon F$_2$ structure function in $\\gamma\\,\\gamma$ collisions. These 14 $\\alpha_s$ determinations are reviewed, and the perspectives of reduction of their present uncertainties are discussed.

  19. Dust properties of Lyman-break galaxies at z ~ 3

    Science.gov (United States)

    Álvarez-Márquez, J.; Burgarella, D.; Heinis, S.; Buat, V.; Lo Faro, B.; Béthermin, M.; López-Fortín, C. E.; Cooray, A.; Farrah, D.; Hurley, P.; Ibar, E.; Ilbert, O.; Koekemoer, A. M.; Lemaux, B. C.; Pérez-Fournon, I.; Rodighiero, G.; Salvato, M.; Scott, D.; Taniguchi, Y.; Vieira, J. D.; Wang, L.

    2016-03-01

    Context. Since the mid-1990s, the sample of Lyman-break galaxies (LBGs) has been growing thanks to the increasing sensitivities in the optical and in near-infrared telescopes for objects at z> 2.5. However, the dust properties of the LBGs are poorly known because the samples are small and/or biased against far-infrared (far-IR) or submillimeter (submm) observations. Aims: This work explores from a statistical point of view the far-IR and submm properties of a large sample of LBGs at z ~ 3 that cannot be individually detected from current far-IR observations. Methods: We select a sample of 22, 000 LBGs at 2.5 luminosity (LFUV), UV continuum slope (βUV), and stellar mass (M∗) to better sample their variety. We stack in PACS (100 and 160 μm) images from PACS Evolution Probe survey (PEP), SPIRE (250, 350 and 500 μm) images from the Herschel Multi-tied Extragalactic Survey (HerMES) programs, and AzTEC (1.1 mm) images from the Atacama Submillimeter Telescope Experiment (ASTE). Our stacking procedure corrects the biases induced by galaxy clustering and incompleteness of our input catalogue in dense regions. Results: We obtain the full infrared spectral energy distributions (SED) of subsamples of LBGs and derive the mean IR luminosity as a function of LFUV, βUV, and M∗. The average IRX (or dust attenuation) is roughly constant over the LFUV range, with a mean of 7.9 (1.8 mag). However, it is correlated with βUV, AFUV = (3.15 ± 0.12) + (1.47 ± 0.14) βUV, and stellar mass, log (IRX) = (0.84 ± 0.11)log (M∗/ 1010.35) + 1.17 ± 0.05. We investigate using a statistically controlled stacking analysis as a function of (M∗, βUV), the dispersion of the IRX-βUV and IRX-M∗ plane. On the one hand, the dust attenuation shows a departure of up to 2.8 mag above the mean IRX-βUV relation when log (M∗ [ M⊙ ]) increases from 9.75 to 11.5 in the same βUV bin. This strongly suggests that M∗ plays an important role in shaping the IRX-βUV plane. On the other hand

  20. Cytosolic phospholipase A2 alpha amplifies early cyclooxygenase-2 expression, oxidative stress and MAP kinase phosphorylation after cerebral ischemia in mice

    Directory of Open Access Journals (Sweden)

    Koehler Raymond C

    2010-07-01

    Full Text Available Abstract Background The enzyme cytosolic phospholipase A2 alpha (cPLA2α has been implicated in the progression of cerebral injury following ischemia and reperfusion. Previous studies in rodents suggest that cPLA2α enhances delayed injury extension and disruption of the blood brain barrier many hours after reperfusion. In this study we investigated the role of cPLA2α in early ischemic cerebral injury. Methods Middle cerebral artery occlusion (MCAO was performed on cPLA2α+/+ and cPLA2α-/- mice for 2 hours followed by 0, 2, or 6 hours of reperfusion. The levels of cPLA2α, cyclooxygenase-2, neuronal morphology and reactive oxygen species in the ischemic and contralateral hemispheres were evaluated by light and fluorescent microscopy. PGE2 content was compared between genotypes and hemispheres after MCAO and MCAO and 6 hours reperfusion. Regional cerebral blood flow was measured during MCAO and phosphorylation of relevant MAPKs in brain protein homogenates was measured by Western analysis after 6 hours of reperfusion. Results Neuronal cPLA2α protein increased by 2-fold immediately after MCAO and returned to pre-MCAO levels after 2 hours reperfusion. Neuronal cyclooxygenase-2 induction and PGE2 concentration were greater in cPLA2α+/+ compared to cPLA2α-/- ischemic cortex. Neuronal swelling in ischemic regions was significantly greater in the cPLA2α+/+ than in cPLA2α-/- brains (+/+: 2.2 ± 0.3 fold vs. -/-: 1.7 ± 0.4 fold increase; P 2α+/+ ischemic core than in cPLA2α-/- (+/+: 7.12 ± 1.2 fold vs. -/-: 3.1 ± 1.4 fold; P 2α+/+, but not cPLA2α-/-, had disruption of neuron morphology and decreased PGE2 content. Phosphorylation of the MAPKs-p38, ERK 1/2, and MEK 1/2-was significantly greater in cPLA2a+/+ than in cPLA2α-/- ischemic cortex 6 hours after reperfusion. Conclusions These results indicate that cPLA2α modulates the earliest molecular and injury responses after cerebral ischemia and have implications for the potential clinical

  1. Observed Faraday Effects in Damped Lyα Absorbers and Lyman Limit Systems: The Magnetized Environment of Galactic Building Blocks at Redshift = 2

    Science.gov (United States)

    Farnes, J. S.; Rudnick, L.; Gaensler, B. M.; Haverkorn, M.; O'Sullivan, S. P.; Curran, S. J.

    2017-06-01

    Protogalactic environments are typically identified using quasar absorption lines and can manifest as Damped Lyman-alpha Absorbers (DLAs) and Lyman Limit Systems (LLSs). We use radio observations of Faraday effects to test whether these galactic building blocks host a magnetized medium, by combining DLA and LLS detections with 1.4 GHz polarization data from the NRAO VLA Sky Survey (NVSS). We obtain a control, a DLA, and an LLS sample consisting of 114, 19, and 27 lines of sight, respectively. Using a Bayesian framework and weakly informative priors, we are unable to detect either coherent or random magnetic fields in DLAs: the regular coherent fields must be ≤slant 2.8 μG, and the lack of depolarization suggests the weakly magnetized gas in DLAs is non-turbulent and quiescent. However, we find a mild suggestive indication that LLSs have coherent magnetic fields, with a 71.5% probability that LLSs have higher | {RM}| than a control, although this is sensitive to the redshift distribution. We also find a strong indication that LLSs host random magnetic fields, with a 95.5% probability that LLS lines of sight have lower polarized fractions than a control. The regular coherent fields within the LLSs must be ≤slant 2.4 μG, and the magnetized gas must be highly turbulent with a typical turbulent length scale on the order of ≈5-20 pc. Our results are consistent with the standard dynamo paradigm, whereby magnetism in protogalaxies increases in coherence over cosmic time, and with a hierarchical galaxy formation scenario, with the DLAs and LLSs exploring different stages of magnetic field evolution in galaxies.

  2. Tissue-specific expression of the human laminin alpha5-chain, and mapping of the gene to human chromosome 20q13.2-13.3 and to distal mouse chromosome 2 near the locus for the ragged (Ra) mutation

    DEFF Research Database (Denmark)

    Durkin, M E; Loechel, F; Mattei, M G

    1997-01-01

    To investigate the function of the laminin alpha5-chain, previously identified in mice, cDNA clones encoding the 953-amino-acid carboxy terminal G-domain of the human laminin alpha5-chain were characterized. Northern blot analysis showed that the laminin alpha5-chain is expressed in human placenta...

  3. Exploring the Overabundance of ULXs in Metal- and Dust-poor Local Lyman Break Analogs

    Science.gov (United States)

    Basu-Zych, Antara R.; Lehmer, Bret; Fragos, Tassos; Hornschemeier, Ann; Yukita, Mihoko; Zezas, Andreas; Ptak, Andy

    2016-02-01

    We have studied high-mass X-ray binary (HMXB) populations within two low-metallicity, starburst galaxies, Haro 11 and VV 114. These galaxies serve as analogs to high-redshift (z\\gt 2) Lyman break galaxies and, within the larger sample of Lyman break analogs (LBAs), they are sufficiently nearby (crowded lower-luminosity HMXBs using the star-forming galaxy XLF and then vary the XLF normalizations and bright-end slopes until we reproduce the observed point source luminosity distributions. We find that these LBAs have a shallower bright-end slope ({γ }2=1.90) than the standard XLF ({γ }2=2.73). If we conservatively assume that the brightest X-ray source from each galaxy is powered by an accreting supermassive black hole rather than an HMXB and eliminate these sources from consideration, the luminosity distribution becomes poorly constrained but does appear to be consistent with a standard XLF.

  4. On the selection of damped Lyman α systems using Mg II absorption at 2 < zabs < 4

    Science.gov (United States)

    Berg, T. A. M.; Ellison, S. L.; Prochaska, J. X.; Sánchez-Ramírez, R.; Lopez, S.; D'Odorico, V.; Becker, G.; Christensen, L.; Cupani, G.; Denney, K.; Worseck, G.

    2017-01-01

    The XQ-100 survey provides optical and near-infrared coverage of 36 blindly selected, intervening damped Lyman α systems (DLAs) at 2 frame equivalent width (W0^{2796}) at these redshifts. Of the 29 DLAs with clean Mg II profiles, we find that six (20 per cent of DLAs) have W0^{2796} effect on the H I-weighted mean metallicity.

  5. New Constraints on the Lyman Continuum Escape Fraction at z~1.3

    CERN Document Server

    Siana, Brian; Colbert, James; Ferguson, Henry C; Dickinson, Mark; Brown, Thomas M; Conselice, Christopher J; de Mello, Duilia F; Gardner, Jonathan P; Giavalisco, Mauro; Menanteau, Felipe

    2007-01-01

    We examine deep far-ultraviolet (1600 Angstrom) imaging of the Hubble Deep Field-North (HDFN) and the Hubble Ultra Deep Field (HUDF) to search for leaking Lyman continuum radiation from starburst galaxies at z~1.3. There are 21 (primarily sub-L*) galaxies with spectroscopic redshifts between 1.1Lyman continuum ratio, f_1500/f_700, and allowing a conversion from f_700 limits to relative escape fractions. We show that previous high-redshift studies may have underestimated the amplitude of the Lyman Break, and thus the relative escape fraction, by a factor of ~2. Once the starburst age and intergalactic HI absorption are accounted for, 18 galaxies in our sample have limits to the relative escape fraction, f_esc,rel < 1.0 with some limits as low as f_esc,rel < 0.10 and a sta...

  6. Narrowband Lyman-Continuum Imaging of Galaxies at z ~ 2.85

    CERN Document Server

    Mostardi, Robin E; Nestor, Daniel B; Steidel, Charles C; Reddy, Naveen A

    2013-01-01

    We present results from a survey for z~2.85 Lyman-Continuum (LyC) emission in the HS1549+1933 field and place constraints on the amount of ionizing radiation escaping from star-forming galaxies. Using a custom narrowband filter (NB3420) tuned to wavelengths just below the Lyman limit at z>=2.82$, we probe the LyC spectral region of 49 Lyman break galaxies (LBGs) and 70 Lya-emitters (LAEs) spectroscopically confirmed at z>=2.82, as well as 58 z~2.85 LAE photometric candidates. Four LBGs and 19 LAEs are detected in NB3420. Using V-band data probing the rest-frame non-ionizing UV, we observe that many NB3420-detected galaxies exhibit spatial offsets between their LyC and non-ionizing UV emission and are characterized by extremely blue NB3420-V colors, corresponding to low ratios of non-ionizing to ionizing radiation (F_UV/F_LyC) that are in tension with current stellar population synthesis models. We measure average values of (F_UV/F_LyC) for our spectroscopically confirmed LBG and LAE samples, correcting for fo...

  7. The HST/ACS+WFC3 Survey for Lyman Limit Systems. II. Science

    Science.gov (United States)

    O'Meara, John M.; Prochaska, J. Xavier; Worseck, Gabor; Chen, Hsiao-Wen; Madau, Piero

    2013-03-01

    We present the first science results from our Hubble Space Telescope survey for Lyman limit absorption systems (LLS) using the low dispersion spectroscopic modes of the Advanced Camera for Surveys and the Wide Field Camera 3. Through an analysis of 71 quasars, we determine the incidence frequency of LLS per unit redshift and per unit path length, l(z) and l(X), respectively, over the redshift range 1 Prochaska et al. and place constraints on the evolution of λ912 mfp with redshift, including an estimate of the "breakthrough" redshift of z = 1.6. Consistent with results at higher z, we find that a significant fraction of the opacity for absorption of ionizing photons comes from systems with N H I <=1017.5 cm-2 with a value for the total Lyman opacity of τLyman eff = 0.40 ± 0.15. Finally, we determine that at minimum, a 5-parameter (4 power law) model is needed to describe the column density distribution function f(N H I , X) at z ~ 2.4, find that f(N H I , X) undergoes no significant change in shape between z ~ 2.4 and z ~ 3.7, and provide our best fit model for f(N H I , X).

  8. Exploring the nature of the Lyman-α emitter CR7

    Science.gov (United States)

    Hartwig, Tilman; Latif, Muhammad A.; Magg, Mattis; Bromm, Volker; Klessen, Ralf S.; Glover, Simon C. O.; Whalen, Daniel J.; Pellegrini, Eric W.; Volonteri, Marta

    2016-10-01

    CR7 is the brightest Lyman-α emitter observed at z > 6, which shows very strong Lyman-α and He II 1640 Å line luminosities, but no metal-line emission. Previous studies suggest that CR7 hosts either young primordial stars with a total stellar mass of ˜107 M⊙ or a black hole of ≳106 M⊙. Here, we explore different formation scenarios for CR7 with a semi-analytical model, based on the random sampling of dark matter merger trees. We are unable to reproduce the observational constraints with a primordial stellar source, given our model assumptions, due to the short stellar lifetimes and the early metal enrichment. Black holes that are the remnants of the first stars are either not massive enough, or reside in metal-polluted haloes, ruling out this possible explanation of CR7. Our models instead suggest that direct collapse black holes, which form in metal-free haloes exposed to large Lyman-Werner fluxes, are more likely the origin of CR7. However, this result is derived under optimistic assumptions and future observations are necessary to further constrain the nature of CR7.

  9. Reconnaissance of the TRAPPIST-1 exoplanet system in the Lyman-α line

    Science.gov (United States)

    Bourrier, V.; Ehrenreich, D.; Wheatley, P. J.; Bolmont, E.; Gillon, M.; de Wit, J.; Burgasser, A. J.; Jehin, E.; Queloz, D.; Triaud, A. H. M. J.

    2017-02-01

    The TRAPPIST-1 system offers the opportunity to characterize terrestrial, potentially habitable planets orbiting a nearby ultracool dwarf star. We performed a four-orbit reconnaissance with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope to study the stellar emission at Lyman-α, to assess the presence of hydrogen exospheres around the two inner planets, and to determine their UV irradiation. We detect the Lyman-α line of TRAPPIST-1, making it the coldest exoplanet host star for which this line has been measured. We reconstruct the intrinsic line profile, showing that it lacks broad wings and is much fainter than expected from the stellar X-ray emission. TRAPPIST-1 has a similar X-ray emission as Proxima Cen but a much lower Ly-α emission. This suggests that TRAPPIST-1 chromosphere is only moderately active compared to its transition region and corona. We estimated the atmospheric mass loss rates for all planets, and found that despite a moderate extreme UV emission the total XUV irradiation could be strong enough to strip the atmospheres of the inner planets in a few billions years. We detect marginal flux decreases at the times of TRAPPIST-1b and c transits, which might originate from stellar activity, but could also hint at the presence of extended hydrogen exospheres. Understanding the origin of these Lyman-α variations will be crucial in assessing the atmospheric stability and potential habitability of the TRAPPIST-1 planets.

  10. A Spectroscopic Search for Leaking Lyman Continuum at z~0.7

    CERN Document Server

    Bridge, Carrie R; Siana, Brian; Scarlata, Claudia; Conselice, Christopher J; Ferguson, Henry C; Brown, Thomas M; Salvato, Mara; Rudie, Gwen C; de Mello, Duilia F; Colbert, James; Gardner, Jonathan P; Giavalisco, Mauro; Armus, Lee

    2010-01-01

    We present the results of rest-frame, UV slitless spectroscopic observations of a sample of 32 z~0.7 Lyman break galaxy (LBG) analogs in the COSMOS field. The spectroscopic search was performed with the Solar Blind Channel (SBC) on Hubble Space Telescope. We report the detection of leaking Lyman continuum (LyC) radiation from an AGN-starburst composite. While we find no direct detections of LyC emission in the remainder of our sample, we achieve individual lower limits (3 sigma) of the observed non-ionizing UV to LyC flux density ratios, f_{nu}(1500A)/f_{nu}(830A) of 20 to 204 (median of 73.5) and 378.7 for the stack. Assuming an intrinsic Lyman break of 3.4 and an intergalactic medium (IGM) transmission of LyC photons along the line of sight to the galaxy of 85% we report an upper limit for the relative escape fraction in individual galaxies of 0.02 - 0.19 and a stacked 3 sigma upper limit of 0.01. We find no indication of a relative escape fraction near unity as seen in some LBGs at z~3. Our UV spectra achi...

  11. The Great Observatories Origins Deep Survey: Constraints on the Lyman Continuum Escape Fraction Distribution of Lyman--Break Galaxies at 3.4

    CERN Document Server

    Vanzella, E; Inoue, A; Nonino, M; Fontanot, F; Cristiani, S; Grazian, A; Dickinson, M; Stern, D; Tozzi, P; Giallongo, E; Ferguson, H; Spinrad, H; Boutsia, K; Fontana, A; Rosati, P

    2010-01-01

    We use ultra-deep ultraviolet VLT/VIMOS intermediate-band and VLT/FORS1 narrow-band imaging in the GOODS Southern field to derive limits on the distribution of the escape fraction (f_esc) of ionizing radiation for L >~ L*(z=3) Lyman Break Galaxies (LBGs) at redshift 3.4--4.5. Only one LBG, at redshift z=3.795, is detected in its Lyman continuum (LyC; S/N~5.5), the highest redshift galaxy currently known with a direct detection. Its ultraviolet morphology is quite compact (R_eff=0.8, kpc physical). Three out of seven AGN are also detected in their LyC, including one at redshift z=3.951 and z850 = 26.1. From stacked data (LBGs) we set an upper limit to the average f_esc in the range 5%--20%, depending on the how the data are selected (e.g., by magnitude and/or redshift). We undertake extensive Monte Carlo simulations that take into account intergalactic attenuation, stellar population synthesis models, dust extinction and photometric noise in order to explore the moments of the distribution of the escaping radi...

  12. A Search for H-alpha Absorption in the Exosphere of the Transiting Extrasolar Planet HD 209458b

    CERN Document Server

    Winn, J N; Turner, E L; Narita, N; Frye, B L; Aoki, W; Sato, B; Yamada, T; Winn, Joshua N.; Suto, Yasushi; Turner, Edwin L.; Narita, Norio; Frye, Brenda L.; Aoki, Wako; Sato, Bunei; Yamada, Toru

    2004-01-01

    There is evidence that the transiting planet HD 209458b has a large exosphere of neutral hydrogen, based on a 15% decrement in Lyman-alpha flux that was observed by Vidal-Madjar et al. during transits. Here we report upper limits on Balmer-alpha (H-alpha) absorption by the exosphere. The results are based on optical spectra of the parent star obtained with the Subaru High Dispersion Spectrograph. Comparison of the spectra taken inside and outside of transit reveals no exospheric H-alpha signal greater than 0.1% within a 5.1AA band (chosen to have the same Dlambda/lambda as the 15% Ly-alpha absorption). The corresponding limit on the column density of n=2 neutral hydrogen is N_2 <~ 10^9 cm^{-2}. This limit constrains proposed models involving a hot (~10^4 K) and hydrodynamically escaping exosphere.

  13. Linking Ly-alpha and Low-Ionization Transitions at Low Optical Depth

    CERN Document Server

    Jaskot, A E

    2014-01-01

    We suggest that low optical depth in the Lyman continuum (LyC) may relate the Ly-alpha emission, C II and Si II absorption, and C II* and Si II* emission seen in high-redshift galaxies. We base this analysis on Hubble Space Telescope COS spectra of four Green Pea (GP) galaxies, which may be analogs of z>2 Ly-alpha emitters (LAEs). In the two GPs with the strongest Ly-alpha emission, the Ly-alpha line profiles do not show the typical effects of resonant scattering. Instead, the Ly-alpha profiles resemble the H-alpha line profiles of evolved star ejecta, suggesting that the Ly-alpha emission originates from a low column density and similar outflow geometry. The weak C II absorption and presence of non-resonant C II* emission in these GPs support this interpretation and imply a low LyC optical depth along the line of sight. In two additional GPs, weak Ly-alpha emission and strong C II absorption suggest a higher optical depth. These two GPs differ in their Ly-alpha profile shapes and C II* emission strengths, ho...

  14. Shadow of a Colossus: A z=2.45 Galaxy Protocluster Detected in 3D Ly-a Forest Tomographic Mapping of the COSMOS Field

    CERN Document Server

    Lee, Khee-Gan; White, Martin; Prochaska, J Xavier; Font-Ribera, Andreu; Schlegel, David J; Rich, R Michael; Suzuki, Nao; Stark, Casey W; Fevre, Olivier Le; Nugent, Peter E; Salvato, Mara; Zamorani, Gianni

    2015-01-01

    Using moderate-resolution optical spectra from 58 background Lyman-break galaxies and quasars at $z\\sim 2.3-3$ within a $11.5'\\times13.5'$ area of the COSMOS field ($\\sim 1200\\,\\mathrm{deg}^2$ projected area density or $\\sim 2.4\\,h^{-1}\\,\\mathrm{Mpc}$ mean transverse separation), we reconstruct a 3D tomographic map of the foreground Ly$\\alpha$ forest absorption at $2.2map. We find an extended IGM overdensity with deep absorption troughs at $z=2.45$ associated with a recently-discovered galaxy protocluster at the same redshift. Based on simulations matched to our data, we estimate the enclosed dark matter mass within this IGM overdensity to be $M_{\\rm dm} (z=2.45) = (9\\pm4)\\times 10^{13}\\,h^{-1}\\,\\mathrm{M_\\o...

  15. The Building the Bridge survey for z=3 Ly-alpha emitting galaxies II: Completion of the survey

    CERN Document Server

    Grove, L F; Ledoux, C; Limousin, M; Møller, P; Nilsson, K; Thomsen, B

    2009-01-01

    (Abridged). We aim at bridging the gap between absorption selected and emission selected galaxies at z~3 by probing the faint end of the luminosity function of star-forming galaxies at z~3. We have performed narrow-band imaging in three fields with intervening QSO absorbers (a damped Ly$\\alpha$ absorber and two Lyman-limit systems) using the VLT. We target Ly-alpha at redshifts 2.85, 3.15 and 3.20. We find a consistent surface density of about 10 Ly-alpha-emitters per square arcmin per unit redshift in all three fields down to our detection limit of about 3x10^41 ergs s^-1. The luminosity function is consistent with what has been found by other surveys at similar redshifts. About 85% of the sources are fainter than the canonical limit of R=25.5 for most Lyman-break galaxy surveys. In none of the three fields do we detect the emission counterparts of the QSO absorbers. In particular we do not detect the counterpart of the z=2.85 damped Ly-alpha absorber towards Q2138-4427. Narrow-band surveys for Ly-alpha emit...

  16. Clustering Segregation with Ultraviolet Luminosity in Lyman Break Galaxies at z~3 and Its Implications

    Science.gov (United States)

    Giavalisco, Mauro; Dickinson, Mark

    2001-03-01

    We report on the clustering properties of Lyman break galaxies (LBGs) at z~3. The correlation length of flux-limited samples of LBGs depends on their rest-frame ultraviolet (UV) luminosity at λ~1700 Å, with fainter galaxies being less strongly clustered in space. We have used three samples with progressively fainter flux limits: two extracted from our ground-based survey and one from the Hubble Deep Fields (both North and South). The correlation length decreases by a factor of ~3 over the range of limiting magnitudes that we have probed, namely, 25limit include galaxies with smaller mass. We have compared the observed scaling properties of the clustering strength with those predicted for cold dark matter (CDM) halos and found that (1) the clustering strength of LBGs follows, within the errors, the same scaling law with the volume density as the halos; and (2) the scaling law predicted for the galaxies using the halo mass spectrum and a number of models for the relationship that maps the halos' mass into the galaxies' UV luminosity depends only on how tightly mass and UV luminosity correlate but is otherwise insensitive to the details of the models. We interpret these results as additional evidence that the strong spatial clustering of LBGs is due to galaxy biasing, supporting the theory of biased galaxy formation and gravitational instability as the primary physical mechanism for the formation of structure. We have also fitted models of the mass-UV luminosity relationship to the data to reproduce simultaneously from the CDM halo mass spectrum the dependence of the correlation length with the UV luminosity and the luminosity function. We have found that (1) a scale invariant relationship between mass and UV luminosity (e.g., a power law) is not supported by the observations, suggesting that the properties of star formation of galaxies change along the mass spectrum of the observed LBGs; (2) the scatter of the UV luminosity of LBGs of given mass must be relatively

  17. The ionizing photon production efficiency of compact z~0.3 Lyman continuum leakers and comparison with high redshift galaxies

    CERN Document Server

    Schaerer, D; Verhamme, A; Orlitova, I; Thuan, T X; Worseck, G; Guseva, N

    2016-01-01

    We have recently discovered five Lyman continuum leaking galaxies at z~0.3, selected for their compactness, intense star-formation, and high [OIII]/[OII] ratio (Izotov et al. 2016ab). Here we derive their ionizing photon production efficiency, a fundamental quantity for inferring the number of photons available to reionize the Universe, for the first time for galaxies with confirmed strong Lyman continuum escape (fesc~6-13%). We find an ionizing photon production per unit UV luminosity, which is a factor 2-6 times higher than the canonical value when reported to their observed UV luminosity. After correction for extinction this value is close to the canonical value. The properties of our five Lyman continuum leakers are found to be very similar to those of the confirmed z=3.218 leaker Ion2 from de Barros et al. (2016) and very similar to those of typical star-forming galaxies at z>~6. Our results suggest that UV bright galaxies at high-z such as Lyman break galaxies can be Lyman continuum leakers and that the...

  18. Metal Abundances in a Damped Lyman-alpha System Along Two Lines of Sight at z=0.93

    CERN Document Server

    López, S; Gregg, M D; Wisotzki, L; Wucknitz, O; Guzman, A

    2005-01-01

    We study metal abundances in the z=0.9313 damped Lya system observed in the two lines-of-sight, A and B, toward the gravitationally-lensed double QSO HE0512-3329. Spatially resolved STIS spectra constrain the neutral-gas column density to be LogN(HI)=20.5 in both Aand B. UVES spectra (spectral resolution FWHM=9.8 km/s) show, in contrast, significant line-of-sight differences in the column densities of MnII and FeII; these are not due to observational systematics. We find that [Mn/H]=-1.44 and [Fe/H]=-1.52 in damped Lya system A, while [Mn/H]=-0.98 and [Fe/H]>-1.32, and possibly as high as [Fe/H] approx. -1 in damped Lya system B. A careful assessment of possible systematic errors leads us to conclude that these transverse differences are significant at a 5 sigma level or greater. Although nucleosynthesis effects may also be at play, we favor differential dust-depletion as the main mechanism producing the observed abundance gradient. The transverse separation is 5 kpc at the redshift of the absorber, which is ...

  19. Search for cold gas in z>2 damped Lyman-alpha systems: 21-cm and H_2 absorption

    CERN Document Server

    Srianand, R; Petitjean, P; Noterdaeme, P; Ledoux, C; Salter, C J; Saikia, D J

    2011-01-01

    (Abridged) We present the results of a systematic GBT and GMRT survey for 21-cm absorption in a sample of 10 DLAs at 2 2 is predominantly constituted by WNM. The detection rate of 21-cm absorption seems to be higher for systems with higher N(HI) or metallicity. However, no clear correlation is found between the integrated 21-cm optical depth (or spin temperature) and either N(HI), metallicity or velocity spread of the low ionization species. There are 13 DLAs in our sample for which high resolution optical spectra covering the expected wavelength range of H_2 absorption are available. We report the detection of H_2 molecules in the z_abs = 3.3871 21-cm absorber towards J0203+1134 (PKS 0201+113). In 8 cases, neither H_2 nor 21-cm absorption are detected. The lack of 21-cm and H_2 absorption in these systems can be explained if most of the HI in these DLAs originate from low density high temperature gas. In one case we have a DLA with 21-cm absorption not showing H_2 absorption. In two cases, both species are d...

  20. Lyman-Alpha Emitting Galaxies as a Probe of Reionization: Large-Scale Bubble Morphology and Small-Scale Absorbers

    CERN Document Server

    Kakiichi, Koki; Ciardi, Benedetta; Graziani, Luca

    2015-01-01

    The visibility of LyA emitting galaxies during the Epoch of Reionization is controlled by both diffuse HI patches in large-scale bubble morphology and small-scale absorbers. To investigate the impact on LyA photons, we apply a novel combination of analytic and numerical calculations to three scenarios: (i) the `bubble' model, where only diffuse HI outside ionized bubbles is present; (ii) the `web' model, where HI exists only in overdense self-shielded gas; and (iii) the more realistic 'web-bubble' model, which contains both. Our analysis confirms that there is a degeneracy between the ionization structure of the intergalactic medium (IGM) and the HI fraction inferred from LyA surveys, as the three models suppress LyA flux equally with very different HI fractions. We argue that a joint analysis of the LyA luminosity function and the rest-frame equivalent width distribution/LyA fraction can break this degeneracy and provide constraints on the reionization history and its topology. We further show that constrain...