WorldWideScience

Sample records for galaxies host bars

  1. Do Low Surface Brightness Galaxies Host Stellar Bars?

    International Nuclear Information System (INIS)

    Cervantes Sodi, Bernardo; Sánchez García, Osbaldo

    2017-01-01

    With the aim of assessing if low surface brightness galaxies host stellar bars and by studying the dependence of the occurrence of bars as a function of surface brightness, we use the Galaxy Zoo 2 data set to construct a large volume-limited sample of galaxies and then segregate these galaxies as having low or high surface brightness in terms of their central surface brightness. We find that the fraction of low surface brightness galaxies hosting strong bars is systematically lower than that found for high surface brightness galaxies. The dependence of the bar fraction on the central surface brightness is mostly driven by a correlation of the surface brightness with the spin and the gas richness of the galaxies, showing only a minor dependence on the surface brightness. We also find that the length of the bars is strongly dependent on the surface brightness, and although some of this dependence is attributed to the gas content, even at a fixed gas-to-stellar mass ratio, high surface brightness galaxies host longer bars than their low surface brightness counterparts, which we attribute to an anticorrelation of the surface brightness with the spin.

  2. Galaxy Zoo: Observing secular evolution through bars

    International Nuclear Information System (INIS)

    Cheung, Edmond; Faber, S. M.; Koo, David C.; Athanassoula, E.; Bosma, A.; Masters, Karen L.; Nichol, Robert C.; Melvin, Thomas; Bell, Eric F.; Lintott, Chris; Schawinski, Kevin; Skibba, Ramin A.; Willett, Kyle W.

    2013-01-01

    In this paper, we use the Galaxy Zoo 2 data set to study the behavior of bars in disk galaxies as a function of specific star formation rate (SSFR) and bulge prominence. Our sample consists of 13,295 disk galaxies, with an overall (strong) bar fraction of 23.6% ± 0.4%, of which 1154 barred galaxies also have bar length (BL) measurements. These samples are the largest ever used to study the role of bars in galaxy evolution. We find that the likelihood of a galaxy hosting a bar is anticorrelated with SSFR, regardless of stellar mass or bulge prominence. We find that the trends of bar likelihood and BL with bulge prominence are bimodal with SSFR. We interpret these observations using state-of-the-art simulations of bar evolution that include live halos and the effects of gas and star formation. We suggest our observed trends of bar likelihood with SSFR are driven by the gas fraction of the disks, a factor demonstrated to significantly retard both bar formation and evolution in models. We interpret the bimodal relationship between bulge prominence and bar properties as being due to the complicated effects of classical bulges and central mass concentrations on bar evolution and also to the growth of disky pseudobulges by bar evolution. These results represent empirical evidence for secular evolution driven by bars in disk galaxies. This work suggests that bars are not stagnant structures within disk galaxies but are a critical evolutionary driver of their host galaxies in the local universe (z < 1).

  3. Chemical enrichment in isolated barred spiral galaxies.

    Science.gov (United States)

    Martel, Hugo; Carles, Christian; Robichaud, Fidéle; Ellison, Sara L.; Williamson, David J.

    2018-04-01

    To investigate the role of bars in the chemical evolution of isolated disc galaxies, we performed a series of 39 gas dynamical simulations of isolated barred and unbarred galaxies with various masses, initial gas fractions, and AGN feedback models. The presence of a bar drives a substantial amount of gas toward the central region of the galaxy. In the most massive galaxies, this results in a violent starburst, followed by a drop in star formation resulting from gas exhaustion. The time delay between Type Ia and Type II supernovae explosions means that barred galaxies experience a rapid increase in [O/H] in the central region, and a much more gradual increase in [Fe/H]. In unbarred galaxies, star formation proceeds at a slow and steady rate, and oxygen and iron are produced at steady rates which are similar except for a time offset. Comparing the abundance ratios in barred and unbarred galaxies with the same central stellar mass M*, we find in barred galaxies an enhancement of 0.07 dex in [O/H], 0.05 dex in [Fe/H], and 0.05 dex in [O/Fe]. The [O/H] enhancement is in excellent agreement with observations from the SDSS. The initial gas fraction has very little effect on the abundance ratios in barred and unbarred galaxies, unless the galaxies experience a starburst. We considered AGN-host galaxies located near the bottom of the AGN regime, M* ≳ 3 × 1010M⊙, where AGN feedback dominates over supernovae feedback. We found that the impact of AGN feedback on the central abundances is marginal.

  4. Companions of Bright Barred Shapley Ames Galaxies

    OpenAIRE

    Garcia-Barreto, J. Antonio; Carrillo, Rene; Vera-Villamizar, Nelson

    2003-01-01

    Companion galaxy environment for a subset of 78 bright and nearby barred galaxies from the Shapley Ames Catalog is presented. Among spiral barred galaxies there are Seyfert galaxies, galaxies with circumnuclear structures, galaxies not associated with any large scale galaxy cloud structure, galaxies with peculiar disk morphology (crooked arms) and galaxies with normal disk morphology; the list includes all Hubble types. The companion galaxy list includes number of companion galaxies within 20...

  5. STELLAR, GAS, AND DARK MATTER CONTENT OF BARRED GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes Sodi, Bernardo, E-mail: b.cervantes@crya.unam.mx [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Campus Morelia, A.P. 3-72, C.P. 58089 Michoacán, México (Mexico)

    2017-01-20

    We select a sample of galaxies from the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7) where galaxies are classified, through visual inspection, as hosting strong bars, weak bars, or as unbarred galaxies, and make use of H i mass and kinematic information from the Arecibo Legacy Fast ALFA survey catalog, to study the stellar, atomic gas, and dark matter content of barred disk galaxies. We find, in agreement with previous studies, that the bar fraction increases with increasing stellar mass. A similar trend is found with total baryonic mass, although the dependence is not as strong as with stellar mass, due to the contribution of gas. The bar fraction shows a decrease with increasing gas mass fraction. This anticorrelation between the likelihood of a galaxy hosting a bar with the gas richness of the galaxy results from the inhibiting effect the gas has in the formation of bars. We also find that for massive galaxies with stellar masses larger than 10{sup 10} M {sub ⊙}, at fixed stellar mass, the bar fraction decreases with increasing global halo mass (i.e., halo mass measured up to a radius of the order of the H i disk extent).

  6. A Modern Picture of Barred Galaxy Dynamics

    Science.gov (United States)

    Petersen, Michael; Weinberg, Martin; Katz, Neal

    2018-01-01

    Observations of disk galaxies suggest that bars are responsible for altering global galaxy parameters (e.g. structures, gas fraction, star formation rate). The canonical understanding of the mechanisms underpinning bar-driven secular dynamics in disk galaxies has been largely built upon the analysis of linear theory, despite galactic bars being clearly demonstrated to be nonlinear phenomena in n-body simulations. We present simulations of barred Milky Way-like galaxy models designed to elucidate nonlinear barred galaxy dynamics. We have developed two new methodologies for analyzing n-body simulations that give the best of both powerful analytic linear theory and brute force simulation analysis: orbit family identification and multicomponent torque analysis. The software will be offered publicly to the community for their own simulation analysis.The orbit classifier reveals that the details of kinematic components in galactic disks (e.g. the bar, bulge, thin disk, and thick disk components) are powerful discriminators of evolutionary paradigms (i.e. violent instabilities and secular evolution) as well as the basic parameters of the dark matter halo (mass distribution, angular momentum distribution). Multicomponent torque analysis provides a thorough accounting of the transfer of angular momentum between orbits, global patterns, and distinct components in order to better explain the underlying physics which govern the secular evolution of barred disk galaxies.Using these methodologies, we are able to identify the successes and failures of linear theory and traditional n-body simulations en route to a detailed understanding of the control bars exhibit over secular evolution in galaxies. We present explanations for observed physical and velocity structures in observations of barred galaxies alongside predictions for how structures will vary with dynamical properties from galaxy to galaxy as well as over the lifetime of a galaxy, finding that the transfer of angular

  7. Bar formation in simulations of interacting galaxies

    International Nuclear Information System (INIS)

    Luna-Sánchez, Juan Carlos; Rodríguez-Meza, M A; Arrieta, A; Gabbasov, R

    2014-01-01

    In this work we present a study of interacting galaxies using N-body simulations. The initial condition of galaxies are such that they are composed of a bulge, a disc (Freeman model, with no gas), and a halo. For bulge and halo we follow the Dehnen density-pair spherical models. Galaxies are set in a parabolic encounter characterised by the impact parameter and the collision angle subtended by the planes containing each individual galactic discs. The evolution of galaxies are given in terms of the morphology (bar formation, geometry of the bar, minor and major axis length), and the kinematical bar rotation. We show how this characteristics depend on the collision geometry. The dynamics of the collision is given in terms of individual rotation curves, dispersion of velocities of the disc and mass function as functions of the distance to the center of mass of each individual galaxy

  8. The Carnegie-Irvine Galaxy Survey. V. Statistical Study of Bars and Buckled Bars

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhao-Yu [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Science, 80 Nandan Road, Shanghai 200030 (China); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Barth, Aaron J., E-mail: lizy@shao.ac.cn [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA, 92697-4575 (United States)

    2017-08-10

    Simulations have shown that bars are subject to a vertical buckling instability that transforms thin bars into boxy or peanut-shaped structures, but the physical conditions necessary for buckling to occur are not fully understood. We use the large sample of local disk galaxies in the Carnegie-Irvine Galaxy Survey to examine the incidence of bars and buckled bars across the Hubble sequence. Depending on the disk inclination angle ( i ), a buckled bar reveals itself as either a boxy/peanut-shaped bulge (at high i ) or as a barlens structure (at low i ). We visually identify bars, boxy/peanut-shaped bulges, and barlenses, and examine the dependence of bar and buckled bar fractions on host galaxy properties, including Hubble type, stellar mass, color, and gas mass fraction. We find that the barred and unbarred disks show similar distributions in these physical parameters. The bar fraction is higher (70%–80%) in late-type disks with low stellar mass ( M {sub *} < 10{sup 10.5} M {sub ⊙}) and high gas mass ratio. In contrast, the buckled bar fraction increases to 80% toward massive and early-type disks ( M {sub *} > 10{sup 10.5} M {sub ⊙}), and decreases with higher gas mass ratio. These results suggest that bars are more difficult to grow in massive disks that are dynamically hotter than low-mass disks. However, once a bar forms, it can easily buckle in the massive disks, where a deeper potential can sustain the vertical resonant orbits. We also find a probable buckling bar candidate (ESO 506−G004) that could provide further clues to understand the timescale of the buckling process.

  9. Towards understanding the dynamics of the bar/bulge region in our Galaxy

    Directory of Open Access Journals (Sweden)

    Athanassoula E.

    2012-02-01

    Full Text Available I review some of the work on bars which is closely linked to the bar/bulge system in our Galaxy. Several independent studies, using totally independent methods, come to the same results about the 3D structure of a bar, i.e., that a bar is composed of a vertically thick inner part and a vertically thin outer part. I give examples of this from simulations and substantiate the discussion with input from orbital structure analysis and from observations. The thick part has a considerably shorter radial extent than the thin part. I then see how this applies to our Galaxy, where two bars have been reported, the COBE/DIRBE bar and the Long bar. Comparing their extents and making the reasonable and necessary assumption that our Galaxy has properties similar to those of other galaxies of similar type, leads to the conclusion that these two bars can not form a standard double bar system. I then discuss arguments in favour of the two bars being simply different parts of the same bar, the COBE/DIRBE bar being the thick inner part and the Long bar being the thin outer part of this bar. I also very briefly discuss some related new results. I first consider bar formation and evolution in disc galaxies with a gaseous component – including star formation, feedback and evolution – and a triaxial halo. Then I consider bar formation in a fully cosmological context using hydrodynamical LCDM simulations, where the host galaxies grow, accrete matter and significantly evolve during the formation and evolution of the bar.

  10. Star formation suppression and bar ages in nearby barred galaxies

    Science.gov (United States)

    James, P. A.; Percival, S. M.

    2018-03-01

    We present new spectroscopic data for 21 barred spiral galaxies, which we use to explore the effect of bars on disc star formation, and to place constraints on the characteristic lifetimes of bar episodes. The analysis centres on regions of heavily suppressed star formation activity, which we term `star formation deserts'. Long-slit optical spectroscopy is used to determine H β absorption strengths in these desert regions, and comparisons with theoretical stellar population models are used to determine the time since the last significant star formation activity, and hence the ages of the bars. We find typical ages of ˜1 Gyr, but with a broad range, much larger than would be expected from measurement errors alone, extending from ˜0.25 to >4 Gyr. Low-level residual star formation, or mixing of stars from outside the `desert' regions, could result in a doubling of these age estimates. The relatively young ages of the underlying populations coupled with the strong limits on the current star formation rule out a gradual exponential decline in activity, and hence support our assumption of an abrupt truncation event.

  11. Gas Kinematics in GRB Host Galaxies

    DEFF Research Database (Denmark)

    Arabsalmani, Maryam

    The star formation history of the Universe is one of the most complex and interesting chapters in our quest to understand galaxy formation and evolution. Gamma Ray Bursts (GRBs) are beacons of actively star forming galaxies from redshifts near zero back to the cosmic dawn. In addition, they provide...... a unique method for selecting galaxies without a luminosity bias as the GRB detectability is unrelated to the brightness of the host galaxy. Even at the highest redshifts, where the hosts are often too faint to be detected in emission, their properties can be inferred from the absorption features...... selected galaxies. Moreover, it is crucial to investigate whether this galaxy population differs from the general population of star forming galaxies (if GRB hosts are a distinct galaxy population), before applying the findings from this selected population to the general population of galaxies...

  12. Characterizing bars in low surface brightness disc galaxies

    Science.gov (United States)

    Peters, Wesley; Kuzio de Naray, Rachel

    2018-05-01

    In this paper, we use B-band, I-band, and 3.6 μm azimuthal light profiles of four low surface brightness galaxies (LSBs; UGC 628, F568-1, F568-3, F563-V2) to characterize three bar parameters: length, strength, and corotation radius. We employ three techniques to measure the radius of the bars, including a new method using the azimuthal light profiles. We find comparable bar radii between the I-band and 3.6 μm for all four galaxies when using our azimuthal light profile method, and that our bar lengths are comparable to those in high surface brightness galaxies (HSBs). In addition, we find the bar strengths for our galaxies to be smaller than those for HSBs. Finally, we use Fourier transforms of the B-band, I-band, and 3.6 μm images to characterize the bars as either `fast' or `slow' by measuring the corotation radius via phase profiles. When using the B- and I-band phase crossings, we find three of our galaxies have faster than expected relative bar pattern speeds for galaxies expected to be embedded in centrally dense cold dark matter haloes. When using the B-band and 3.6 μm phase crossings, we find more ambiguous results, although the relative bar pattern speeds are still faster than expected. Since we find a very slow bar in F563-V2, we are confident that we are able to differentiate between fast and slow bars. Finally, we find no relation between bar strength and relative bar pattern speed when comparing our LSBs to HSBs.

  13. HOST GALAXY IDENTIFICATION FOR SUPERNOVA SURVEYS

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Ravi R.; Kuhlmann, Steve; Kovacs, Eve; Spinka, Harold; Kessler, Richard; Goldstein, Daniel A.; Liotine, Camille; Pomian, Katarzyna; D’Andrea, Chris B.; Sullivan, Mark; Carretero, Jorge; Castander, Francisco J.; Nichol, Robert C.; Finley, David A.; Fischer, John A.; Foley, Ryan J.; Kim, Alex G.; Papadopoulos, Andreas; Sako, Masao; Scolnic, Daniel M.; Smith, Mathew; Tucker, Brad E.; Uddin, Syed; Wolf, Rachel C.; Yuan, Fang; Abbott, Tim M. C.; Abdalla, Filipe B.; Benoit-Lévy, Aurélien; Bertin, Emmanuel; Brooks, David; Rosell, Aurelio Carnero; Kind, Matias Carrasco; Cunha, Carlos E.; Costa, Luiz N. da; Desai, Shantanu; Doel, Peter; Eifler, Tim F.; Evrard, August E.; Flaugher, Brenna; Fosalba, Pablo; Gaztañaga, Enrique; Gruen, Daniel; Gruendl, Robert; James, David J.; Kuehn, Kyler; Kuropatkin, Nikolay; Maia, Marcio A. G.; Marshall, Jennifer L.; Miquel, Ramon; Plazas, Andrés A.; Romer, A. Kathy; Sánchez, Eusebio; Schubnell, Michael; Sevilla-Noarbe, Ignacio; Sobreira, Flávia; Suchyta, Eric; Swanson, Molly E. C.; Tarle, Gregory; Walker, Alistair R.; Wester, William

    2016-11-08

    Host galaxy identification is a crucial step for modern supernova (SN) surveys such as the Dark Energy Survey and the Large Synoptic Survey Telescope, which will discover SNe by the thousands. Spectroscopic resources are limited, and so in the absence of real-time SN spectra these surveys must rely on host galaxy spectra to obtain accurate redshifts for the Hubble diagram and to improve photometric classification of SNe. In addition, SN luminosities are known to correlate with host-galaxy properties. Therefore, reliable identification of host galaxies is essential for cosmology and SN science. We simulate SN events and their locations within their host galaxies to develop and test methods for matching SNe to their hosts. We use both real and simulated galaxy catalog data from the Advanced Camera for Surveys General Catalog and MICECATv2.0, respectively. We also incorporate "hostless" SNe residing in undetected faint hosts into our analysis, with an assumed hostless rate of 5%. Our fully automated algorithm is run on catalog data and matches SNe to their hosts with 91% accuracy. We find that including a machine learning component, run after the initial matching algorithm, improves the accuracy (purity) of the matching to 97% with a 2% cost in efficiency (true positive rate). Although the exact results are dependent on the details of the survey and the galaxy catalogs used, the method of identifying host galaxies we outline here can be applied to any transient survey.

  14. Barred galaxies in the EAGLE cosmological hydrodynamical simulation

    Science.gov (United States)

    Algorry, David G.; Navarro, Julio F.; Abadi, Mario G.; Sales, Laura V.; Bower, Richard G.; Crain, Robert A.; Dalla Vecchia, Claudio; Frenk, Carlos S.; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2017-07-01

    We examine the properties of barred disc galaxies in a ΛCDM cosmological hydrodynamical simulation from the EAGLE project. Our study follows the formation of 269 discs identified at z = 0 in the stellar mass range 10.6 < log M*/M⊙ < 11. These discs show a wide range of bar strengths, from unbarred discs (≈60 per cent) to weak bars (≈20 per cent) and to strongly barred systems (≈20 per cent). Bars in these systems develop after redshift ≈1.3, on time-scales that depend sensitively on the strength of the pattern. Strong bars develop relatively quickly (in a few Gyr, or roughly ∼10 disc rotation periods) in systems that are disc dominated, gas poor, and have declining rotation curves. Weak bars develop more slowly in systems where the disc is less gravitationally important, and are still growing at z = 0. Unbarred galaxies are comparatively gas-rich discs whose rotation speeds do not exceed the maximum circular velocity of the haloes they inhabit. Bar lengths compare favourably with observations, ranging from 0.2 to 0.8 times the radius containing 90 per cent of the stars. Bars slow down remarkably quickly as they grow, causing the inner regions of the surrounding dark halo to expand. At z = 0 strong bars in simulated galaxies have corotation radii roughly 10 times the bar length. Such slow bars are inconsistent with the few cases where pattern speeds have been measured or inferred observationally, a discrepancy that, if confirmed, might prove a challenge for disc galaxy formation in ΛCDM.

  15. Tidally Induced Bars of Galaxies in Clusters

    Czech Academy of Sciences Publication Activity Database

    Lokas, E.; Ebrová, Ivana; del Pino, A.; Sybilska, A.; Athanassoula, E.; Semczuk, M.; Gajda, G.; Fouquet, S.

    2016-01-01

    Roč. 286, č. 6 (2016), 227/1-227/13 ISSN 0004-637X Institutional support: RVO:67985815 Keywords : galaxies * clusters * evolution Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.533, year: 2016

  16. Connecting Global to Local Parameters in Barred Galaxy Models

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. We present connections between global and local parame- ters in a realistic dynamical model, describing motion in a barred galaxy. Expanding the global model in the vicinity of a stable Lagrange point, we find the potential of a two-dimensional perturbed harmonic oscillator, which describes local motion near the ...

  17. The host galaxy of GRB 990712

    DEFF Research Database (Denmark)

    Christensen, L.; Hjorth, J.; Gorosabel, J.

    2004-01-01

    We present a comprehensive study of the z = 0.43 host galaxy of GRB 990712, involving ground-based photometry, spectroscopy, and HST imaging. The broad-band UBVRIJHKs photometry is used to determine the global spectral energy distribution (SED) of the host galaxy. Comparison with that of known...... galaxy types shows that the host is similar to a moderately kreddened starburst galaxy with a young stellar population. The estimated internal extinction in the host is A(V) = 0.15 +/- 0.1 and the star-formation rate (SFR) from the UV continuum is 1.3 +/- 0.3 M-circle dot yr(-1) (not corrected...... for the effects of extinction). Other galaxy template spectra than starbursts failed to reproduce the observed SED. We also present VLT spectra leading to the detection of Halpha from the GRB host galaxy. A SFR of 2.8 +/- 0.7 M-circle dot yr(-1) is inferred from the Halpha line flux, and the presence of a young...

  18. The host galaxy of GRB 990712

    DEFF Research Database (Denmark)

    Christensen, L.; Hjorth, J.; Gorosabel, J.

    2004-01-01

    galaxy types shows that the host is similar to a moderately kreddened starburst galaxy with a young stellar population. The estimated internal extinction in the host is A(V) = 0.15 +/- 0.1 and the star-formation rate (SFR) from the UV continuum is 1.3 +/- 0.3 M-circle dot yr(-1) (not corrected......We present a comprehensive study of the z = 0.43 host galaxy of GRB 990712, involving ground-based photometry, spectroscopy, and HST imaging. The broad-band UBVRIJHKs photometry is used to determine the global spectral energy distribution (SED) of the host galaxy. Comparison with that of known...... for the effects of extinction). Other galaxy template spectra than starbursts failed to reproduce the observed SED. We also present VLT spectra leading to the detection of Halpha from the GRB host galaxy. A SFR of 2.8 +/- 0.7 M-circle dot yr(-1) is inferred from the Halpha line flux, and the presence of a young...

  19. Speculations on Bar-Driven Evolution of the Galaxy

    Science.gov (United States)

    Sevenster, M. N.

    The Galaxy's has a weak Bar, of SAB-type, and the corotation radius is near 3.5 kpc with the inner-ultra-harmonic resonance near 2.5 kpc, as derived from an unbiased set of stellar positions and losa velocities. I speculate upon - and present some evidence for - a scenario in which the Bar formed about 5 Gyr ago and induced an inward flow of gas that increased the galactic-centre metallicity. The central concentration of the density distribution of the Galaxy may have increased enough to trigger periodic star bursts and the formation of an inner-Lindblad resonance near 1.5 kpc, which may now and in future be the cause for the ongoing dissolution of the Bar.

  20. On wave dark matter in spiral and barred galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Medina, Luis A.; Matos, Tonatiuh [Departamento de Física, Centro de Investigación y de Estudios Avanzados del IPN, A.P. 14-740, 07000 México D.F., México. (Mexico); Bray, Hubert L., E-mail: lmedina@fis.cinvestav.mx, E-mail: bray@math.duke.edu, E-mail: tmatos@fis.cinvestav.mx [Mathematics Department, Duke University, Box 90320, Durham, NC 27708 (United States)

    2015-12-01

    We recover spiral and barred spiral patterns in disk galaxy simulations with a Wave Dark Matter (WDM) background (also known as Scalar Field Dark Matter (SFDM), Ultra-Light Axion (ULA) dark matter, and Bose-Einstein Condensate (BEC) dark matter). Here we show how the interaction between a baryonic disk and its Dark Matter Halo triggers the formation of spiral structures when the halo is allowed to have a triaxial shape and angular momentum. This is a more realistic picture within the WDM model since a non-spherical rotating halo seems to be more natural. By performing hydrodynamic simulations, along with earlier test particles simulations, we demonstrate another important way in which wave dark matter is consistent with observations. The common existence of bars in these simulations is particularly noteworthy. This may have consequences when trying to obtain information about the dark matter distribution in a galaxy, the mere presence of spiral arms or a bar usually indicates that baryonic matter dominates the central region and therefore observations, like rotation curves, may not tell us what the DM distribution is at the halo center. But here we show that spiral arms and bars can develop in DM dominated galaxies with a central density core without supposing its origin on mechanisms intrinsic to the baryonic matter.

  1. Bars in dark matter-dominated dwarf galaxy discs

    Science.gov (United States)

    Marasco, A.; Oman, K. A.; Navarro, J. F.; Frenk, C. S.; Oosterloo, T.

    2018-02-01

    We study the shape and kinematics of simulated dwarf galaxy discs in the APOSTLE suite of ΛCDM cosmological hydrodynamical simulations. We find that a large fraction of these gas-rich, star-forming discs show weak bars in their stellar component, despite being dark matter-dominated systems. The bar pattern shape and orientation reflect the ellipticity of the dark matter potential, and its rotation is locked to the slow figure rotation of the triaxial dark halo. The bar-like nature of the potential induces non-circular motions in the gas component, including strong bisymmetric flows that can be readily seen as m = 3 harmonic perturbations in the H I line-of-sight velocity fields. Similar bisymmetric flows are seen in many galaxies of the THINGS and LITTLE THINGS surveys, although on average their amplitudes are a factor of ˜2 weaker than in our simulated discs. Our results indicate that bar-like patterns may arise even when baryons are not dominant, and that they are common enough to warrant careful consideration when analyzing the gas kinematics of dwarf galaxy discs.

  2. On wave dark matter in spiral and barred galaxies

    International Nuclear Information System (INIS)

    Martinez-Medina, Luis A.; Matos, Tonatiuh; Bray, Hubert L.

    2015-01-01

    We recover spiral and barred spiral patterns in disk galaxy simulations with a Wave Dark Matter (WDM) background (also known as Scalar Field Dark Matter (SFDM), Ultra-Light Axion (ULA) dark matter, and Bose-Einstein Condensate (BEC) dark matter). Here we show how the interaction between a baryonic disk and its Dark Matter Halo triggers the formation of spiral structures when the halo is allowed to have a triaxial shape and angular momentum. This is a more realistic picture within the WDM model since a non-spherical rotating halo seems to be more natural. By performing hydrodynamic simulations, along with earlier test particles simulations, we demonstrate another important way in which wave dark matter is consistent with observations. The common existence of bars in these simulations is particularly noteworthy. This may have consequences when trying to obtain information about the dark matter distribution in a galaxy, the mere presence of spiral arms or a bar usually indicates that baryonic matter dominates the central region and therefore observations, like rotation curves, may not tell us what the DM distribution is at the halo center. But here we show that spiral arms and bars can develop in DM dominated galaxies with a central density core without supposing its origin on mechanisms intrinsic to the baryonic matter

  3. Spectroscopy of superluminous supernova host galaxies

    DEFF Research Database (Denmark)

    Leloudas, G.; Kruehler, T.; Schulze, S

    2015-01-01

    Superluminous supernovae (SLSNe) are very bright explosions that were only discovered recently and that show a preference for occurring in faint dwarf galaxies. Understanding why stellar evolution yields different types of stellar explosions in these environments is fundamental in order to both...... uncover the elusive progenitors of SLSNe and to study star formation in dwarf galaxies. In this paper, we present the first results of our project to study SUperluminous Supernova Host galaxIES, focusing on the sample for which we have obtained spectroscopy. We show that SLSNe-I and SLSNe-R (hydrogen......-poor) often (~50% in our sample) occur in a class of galaxies that is known as Extreme Emission Line Galaxies (EELGs). The probability of this happening by chance is negligible and we therefore conclude that the extreme environmental conditions and the SLSN phenomenon are related. In contrast, SLSNe...

  4. A Local Baseline of the Black Hole Mass - Host Galaxy Scaling Relations for Active Galaxies

    Science.gov (United States)

    Bennert, Vardha

    2017-08-01

    The discovery of relations between supermassive black holes (BHs) and their host-galaxy properties has sparked many observational studies pertaining both to the local Universe and cosmic history. Nevertheless, a clear understanding of their origin and fundamental drivers still eludes us. Studying the evolution of these relations depends on our understanding of the slope and scatter of local relations for active galaxies (AGNs). We propose a SNAP program of a unique sample of 84 local type-1 AGNs, spanning a wide range of BH masses (MBH), morphologies, and stellar masses. The high resolution WFC3/F814W images are essential for a detailed decomposition of the host-galaxy in the presence of a bright AGN point source, resulting in precise measurements of the different host-galaxy components and AGN luminosity free of host-galaxy contamination for a robust determination of MBH. When complemented with spatially-resolved Keck spectra to determine stellar-velocity dispersion within bulge effective radius, this yields a most complete baseline of host-galaxy properties over the entire range of MBH scaling relations. A typical SNAP completion rate results in a sample of 30 objects which will be used to calibrate existing Gemini NIRI and SDSS images. We will study slope and scatter of the relations, dependencies and fundamental drivers. The frequency of pseudo-bulges, bars, and (minor) mergers will reveal the dominant growth mechanism of spheroids. The homogeneous sample will identify any selection biases in the reverberation-mapped AGN sample which serves as a MBH calibrator for the entire Universe. Results will be compared with state-of-the-art semi-analytical models.

  5. Star Formation Quenching in Quasar Host Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Carniani, Stefano, E-mail: sc888@mrao.cam.ac.uk [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Kavli Institute for Cosmology, University of Cambridge, Cambridge (United Kingdom)

    2017-10-16

    Galaxy evolution is likely to be shaped by negative feedback from active galactic nuclei (AGN). In the whole range of redshifts and luminosities studied so far, galaxies hosting an AGN frequently show fast and extended outflows consisting in both ionized and molecular gas. Such outflows could potentially quench the start formation within the host galaxy, but a clear evidence of negative feedback in action is still missing. Hereby I will analyse integral-field spectroscopic data for six quasars at z ~ 2.4 obtained with SINFONI in the H- and K-band. All the quasars show [Oiii]λ5007 line detection of fast, extended outflows. Also, the high signal-to-noise SINFONI observations allow the identification of faint narrow Hα emission (FWHM < 500 km/s), which is spatially extended and associated with star formation in the host galaxy. On paper fast outflows are spatially anti-correlated with star-formation powered emission, i.e., star formation is suppressed in the area affected by the outflow. Nonetheless as narrow, spatially-extended Hα emission, indicating star formation rates of at least 50–100 M{sub ⊙} yr{sup −1}, has been detected, either AGN feedback is not affecting the whole host galaxy, or star formation is completely quenched only by several feedback episodes. On the other hand, a positive feedback scenario, supported by narrow emission in Hα extending along the edges of the outflow cone, suggests that galaxy-wide outflows could also have a twofold role in the evolution of the host galaxy. Finally, I will present CO(3-2) ALMA data for three out of the six QSOs observed with SINFONI. Flux maps obtained for the CO(3-2) transition suggest that molecular gas within the host galaxy is swept away by fast winds. A negative-feedback scenario is supported by the inferred molecular gas mass in all three objects, which is significantly below what observed in non-active main-sequence galaxies at high-z.

  6. The Comparative Observational Study of Timescale of Feedback by Bar Structure in Late-type Galaxies

    Science.gov (United States)

    Woong-bae Woong-bae Zee, Galaxy; Yoon, Suk-jin

    2018-01-01

    We investigate star formation activities of ~400 barred and ~1400 unbarred faced-on late-type galaxies from the SDSS DR13. We find that gas-poor and barred galaxies are considerably show enhanced high central star formation activities, while there is no difference among gas-rich barred and unbarred galaxies regardless of their HI gas content. This seems counter-intuitive given that gas contents simply represent the total star formation rate of galaxies and suggests that there is a time delation between the central gas migration/consumption through bar structures and the enhancement of star formation activity at the centre. We analysed the distribution of the stellar population of specific galaxies with MaNGA (Mapping Nearby Galaxies at APO) IFU survey among the total samples. The gas-poor and barred galaxies show the flatter gradient in metallicity and age with respect to the stellar mass than other types of galaxies, in that their centre is more metal-rich and younger. There is an age difference, about 5-6 Gyrs, between centrally star-forming gas-poor barred galaxies and gas-rich galaxies and this value is a plausible candidate of the longevity of bar feedback. The results indicate that the gas migration/mixing driven by bar structure plays a significant role in the evolution of galaxies in a specific of timescale.

  7. The AGN-host galaxy connection : new insights from the extended ionised gas

    OpenAIRE

    Husemann, Bernd

    2011-01-01

    Active Galactic Nuclei (AGN) are powered by gas accretion onto supermassive Black Holes (BH). The luminosity of AGN can exceed the integrated luminosity of their host galaxies by orders of magnitude, which are then classified as Quasi-Stellar Objects (QSOs). Some mechanisms are needed to trigger the nuclear activity in galaxies and to feed the nuclei with gas. Among several possibilities, such as gravitational interactions, bar instabilities, and smooth gas accretion from the environment, the...

  8. Circumnuclear Structures in Megamaser Host Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Pjanka, Patryk; Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544 (United States); Seth, Anil C. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Braatz, James A.; Lo, Fred K. Y. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Henkel, Christian [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Läsker, Ronald, E-mail: ppjanka@princeton.edu [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, FI-21500 Kaarina (Finland)

    2017-08-01

    Using the Hubble Space Telescope , we identify circumnuclear (100–500 pc scale) structures in nine new H{sub 2}O megamaser host galaxies to understand the flow of matter from kpc-scale galactic structures down to the supermassive black holes (SMBHs) at galactic centers. We double the sample analyzed in a similar way by Greene et al. and consider the properties of the combined sample of 18 sources. We find that disk-like structure is virtually ubiquitous when we can resolve <200 pc scales, in support of the notion that non-axisymmetries on these scales are a necessary condition for SMBH fueling. We perform an analysis of the orientation of our identified nuclear regions and compare it with the orientation of megamaser disks and the kpc-scale disks of the hosts. We find marginal evidence that the disk-like nuclear structures show increasing misalignment from the kpc-scale host galaxy disk as the scale of the structure decreases. In turn, we find that the orientation of both the ∼100 pc scale nuclear structures and their host galaxy large-scale disks is consistent with random with respect to the orientation of their respective megamaser disks.

  9. How do spiral arm contrasts relate to bars, disc breaks and other fundamental galaxy properties?

    Science.gov (United States)

    Bittner, Adrian; Gadotti, Dimitri A.; Elmegreen, Bruce G.; Athanassoula, Evangelie; Elmegreen, Debra M.; Bosma, Albert; Muñoz-Mateos, Juan-Carlos

    2017-10-01

    We investigate how the properties of spiral arms relate to other fundamental galaxy properties, including bars and disc breaks. We use previously published measurements of those properties, and our own measurements of arm and bar contrasts for a large sample of galaxies, using 3.6 μm images from the Spitzer Survey of Stellar Structure in Galaxies. Flocculent galaxies are clearly distinguished from other spiral arm classes, especially by their lower stellar mass and surface density. Multi-armed and grand-design galaxies are similar in most of their fundamental parameters, excluding some bar properties and the bulge-to-total ratio. Based on these results, we revisit the sequence of spiral arm classes, and discuss classical bulges as a necessary condition for standing spiral wave modes in grand-design galaxies. We find a strong correlation between bulge-to-total ratio and bar contrast, and a weaker correlation between arm and bar contrasts. Barred and unbarred galaxies exhibit similar arm contrasts, but the highest arm contrasts are found exclusively in barred galaxies. Interestingly, the bar contrast, and its increase from flocculent to grand-design galaxies, is systematically more significant than that of the arm contrast. We corroborate previous findings concerning a connection between bars and disc breaks. In particular, in grand-design galaxies, the bar contrast correlates with the normalized disc break radius. This does not hold for other spiral arm classes or the arm contrast. Our measurements of arm and bar contrast and radial contrast profiles are publicly available.

  10. Coevolution of Supermassive Black Holes and Their Host Galaxies

    Science.gov (United States)

    Hiner, Kyle Devon

    The role of black holes in galaxy evolution has come under intense scrutiny since it was discovered that every galaxy in the local universe contains a supermassive black hole (SMBH) at its nucleus. The existence of scaling relations between the SMBH and its host galaxy show that their presence is not coincidental, but rather that SMBHs and their hosts have a shared evolution. The nature of this coevolution is still debated with some proposing it to be a natural result of hierarchical merging models, while others invoke SMBH feedback mechanisms that couple BH growth with that of the host galaxy. In this dissertation, I examine different regimes of SMBH activity and host galaxy properties. I investigate a sample of post-starburst galaxies to gain insight into the morphological and spectrophotometric evolution of galaxies through galaxy interactions and mergers. I plot detailed comparisons of the galaxy kinematics as measured from different stellar populations. I also investigate post-starburst galaxies that simultaneously host an AGN. I develop a technique to study the properties of both the host galaxy and the SMBH in these objects, directly investigating the scaling relation between the two. I describe analysis performed on red quasars in another study that directly probes the scaling relations in the non-local universe. Lastly, I conduct SED fitting of quasars to illuminate the differences between two major spectral types, and investigate host galaxy properties including star formation. All of these projects focus on the relationship between the SMBH and host galaxy. I show that a range of galaxy interactions can lead to black hole growth and are part of galaxy evolution over cosmic time.

  11. Statistical Properties of Gamma-Ray Burst Host Galaxies

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Permanent link: http://www.ias.ac.in/article/fulltext/joaa/035/03/0267-0270 ... A statistical analysis of gamma-ray burst host galaxies is presented and a clear metallicity-stellar mass relation is found in our sample. A trend that a more massive host galaxy tends to have a higher star-formation rate is also found.

  12. Do Nuclear Star Clusters and Supermassive Black Holes Follow the Same Host-Galaxy Correlations?

    Directory of Open Access Journals (Sweden)

    Peter Erwin

    2012-01-01

    Full Text Available Studies have suggested that there is a strong correlation between the masses of nuclear star clusters (NSCs and their host galaxies, a correlation which is said to be an extension of the well-known correlations between supermassive black holes (SMBHs and their host galaxies. But careful analysis of disk galaxies—including 2D bulge/disk/bar decompositions—shows that while SMBHs correlate with the stellar mass of the bulge component of galaxies, the masses of NSCs correlate much better with the total galaxy stellar mass. In addition, the mass ratio MNSC/M⋆, tot for NSCs in spirals (at least those with Hubble types Sc and later is typically an order of magnitude smaller than the mass ratio MBH/M⋆, bul of SMBHs. The absence of a universal “central massive object” correlation argues against common formation and growth mechanisms for both SMBHs and NSCs. We also discuss evidence for a break in the NSC-host galaxy correlation, galaxies with Hubble types earlier than Sbc appear to host systematically more massive NSCs than do types Sc and later.

  13. AGN-host galaxy connection: multiwavelength study

    Science.gov (United States)

    Pović, M.; Sánchez-Portal, M.; García, A. M. Pérez; Bongiovanni, A.; Cepa, J.; Cepa

    2013-02-01

    The connection between active galactic nuclei (AGN) and their hosts showed to be important for understanding the formation and evolution of active galaxies. Using X-ray and deep optical data, we study how morphology and colours are related to X-ray properties at redshifts z 300 X-ray detected AGN in the Subaru/XMM-Newton Deep Survey (SXDS; Furusawa et al. 2008) and Groth-Westphal Strip (GWS; Pović et al. 2009) fields. We performed our morphological classification using the galSVM code (Huertas-Company et al. 2008), which is a new method that is particularly suited when dealing with high-redshift sources. To separate objects between X-ray unobscured and obscured, we used X-ray hardness ratio HR(0.5-2 keV/2-4.5 keV). Colour-magnitude diagrams were studied in relationship to redshift, morphology, X-ray obscuration, and X-ray-to-optical flux ratio. Around 50% of X-ray detected AGN at zdetected AGN in both colour-magnitude (CMD) and colour-stellar mass diagrams (Figure 1), the highest number of sources is found to reside in the green valley at redshifts ~ 0.5-1.5. For the first time we studied CMD of these AGN in relation to morphology and X-ray obscuration, finding that they can reside in both early- and late-type hosts, where both morphological types cover similar ranges of X-ray obscuration (Figure 1). Our findings appear to confirm some previous suggestions that X-ray selected AGN residing in the green valley represent a transitional population (e.g. Nandra et al. 2007, Silverman et al. 2008, Treister et al. 2009), quenching star formation by means of different AGN feedback mechanisms and evolving to red-sequence galaxies. More details on analysis and results presented here can be found in Pović et al. 2012.

  14. Cosmic evolution and metal aversion in superluminous supernova host galaxies

    Science.gov (United States)

    Schulze, S.; Krühler, T.; Leloudas, G.; Gorosabel, J.; Mehner, A.; Buchner, J.; Kim, S.; Ibar, E.; Amorín, R.; Herrero-Illana, R.; Anderson, J. P.; Bauer, F. E.; Christensen, L.; de Pasquale, M.; de Ugarte Postigo, A.; Gallazzi, A.; Hjorth, J.; Morrell, N.; Malesani, D.; Sparre, M.; Stalder, B.; Stark, A. A.; Thöne, C. C.; Wheeler, J. C.

    2018-01-01

    The SUperluminous Supernova Host galaxIES survey aims to provide strong new constraints on the progenitors of superluminous supernovae (SLSNe) by understanding the relationship to their host galaxies. We present the photometric properties of 53 H-poor and 16 H-rich SLSN host galaxies out to z ∼ 4. We model their spectral energy distributions to derive physical properties, which we compare with other galaxy populations. At low redshift, H-poor SLSNe are preferentially found in very blue, low-mass galaxies with high average specific star formation rates. As redshift increases, the host population follows the general evolution of star-forming galaxies towards more luminous galaxies. After accounting for secular evolution, we find evidence for differential evolution in galaxy mass, but not in the B band and the far-ultraviolet luminosity (3σ confidence). Most remarkable is the scarcity of hosts with stellar masses above 1010 M⊙ for both classes of SLSNe. In case of H-poor SLSNe, we attribute this to a stifled production efficiency above ∼0.4 solar metallicity. However, we argue that, in addition to low metallicity, a short-lived stellar population is also required to regulate the SLSN production. H-rich SLSNe are found in a very diverse population of star-forming galaxies. Still, the scarcity of massive hosts suggests a stifled production efficiency above ∼0.8 solar metallicity. The large dispersion of the H-rich SLSNe host properties is in stark contrast to those of gamma-ray burst, regular core-collapse SN, and H-poor SLSNe host galaxies. We propose that multiple progenitor channels give rise to this subclass.

  15. An HST study of three very faint GRB host galaxies

    DEFF Research Database (Denmark)

    Jaunsen, A.O.; Andersen, M.I.; Hjorth, J.

    2003-01-01

    As part of the HST/STIS GRB host survey program we present the detection of three faint gamma-ray burst (GRB) host galaxies based on an accurate localisation using ground-based data of the optical afterglows (OAs). A common property of these three hosts is their extreme faintness. The location at...

  16. A New Dataset of Automatically Extracted Structure of Arms and Bars in Spiral Galaxies

    Science.gov (United States)

    Hayes, Wayne B.; Davis, D.

    2012-05-01

    We present an algorithm capable of automatically extracting quantitative structure (bars and arms) from images of spiral galaxies. We have run the algorithm on 30,000 galaxies and compared the results to human classifications generously provided pre-publication by the Galaxy Zoo 2 team. In all available measures, our algorithm agrees with the humans about as well as they agree with each other. In addition we provide objective, quantitative measures not available in human classifications. We provide a preliminary analysis of this dataset to see how the properties of arms and bars vary as a function of basic variables such as environment, redshift, absolute magnitude, and color. We also show how structure can vary across wavebands as well as along and across individual arms and bars. Finally, we present preliminary results of a measurement of the total angular momentum present in our observed set of galaxies with an eye towards determining if there is a preferred "handedness" in the universe.

  17. A study of the effect of bulges on bar formation in disc galaxies

    Science.gov (United States)

    Kataria, Sandeep Kumar; Das, Mousumi

    2018-04-01

    We use N-body simulations of bar formation in isolated galaxies to study the effect of bulge mass and bulge concentration on bar formation. Bars are global disc instabilities that evolve by transferring angular momentum from the inner to outer discs and to the dark matter halo. It is well known that a massive spherical component such as halo in a disc galaxy can make it bar stable. In this study, we explore the effect of another spherical component, the bulge, on bar formation in disc galaxies. In our models, we vary both the bulge mass and concentration. We have used two sets of models: one that has a dense bulge and high surface density disc, and the other model has a less concentrated bulge and a lighter disc. In both models, we vary the bulge to disc mass fraction from 0 to 0.7. Simulations of both the models show that there is an upper cut-off in bulge-to-disc mass ratio Mb/Md above which bars cannot form; the cut-off is smaller for denser bulges (Mb/Md = 0.2) compared to less denser ones (Mb/Md = 0.5). We define a new criterion for bar formation in terms of the ratio of bulge to total radial force (Fb/Ftot) at the disc scale lengths above which bars cannot form. We find that if Fb/Ftot > 0.35, a disc is stable and a bar cannot form. Our results indicate that early-type disc galaxies can still form strong bars in spite of having massive bulges.

  18. Star formation history in barred spiral galaxies - active galactic nucleus feedback

    Science.gov (United States)

    Robichaud, Fidèle; Williamson, David; Martel, Hugo; Kawata, Daisuke; Ellison, Sara L.

    2017-08-01

    We present a numerical study of the impact of active galactic nucleus (AGN) accretion and feedback on the star formation history of barred disc galaxies. Our goal is to determine whether the effect of feedback is positive (enhanced star formation) or negative (quenched star formation), and to what extent. We performed a series of 12 hydrodynamical simulations of disc galaxies, 10 barred and 2 unbarred, with various initial gas fractions and AGN feedback prescriptions. In barred galaxies, gas is driven towards the centre of the galaxy and causes a starburst, followed by a slow decay, while in unbarred galaxies, the star formation rate (SFR) increases slowly and steadily. AGN feedback suppresses star formation near the central black hole. Gas is pushed away from the black hole, and collides head-on with inflowing gas, forming a dense ring at a finite radius where star formation is enhanced. We conclude that both negative and positive feedback are present, and these effects mostly cancel out. There is no net quenching or enhancement in star formation, but rather a displacement of the star formation sites to larger radii. In unbarred galaxies, where the density of the central gas is lower, quenching of star formation near the black hole is more efficient, and enhancement of star formation at larger radii is less efficient. As a result, negative feedback dominates. Lowering the gas fraction reduces the SFR at all radii, whether or not there is a bar or an AGN.

  19. Stellar Photometric Structures of the Host Galaxies of Nearby Type 1 Active Galactic Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Minjin [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Peng, Chien Y. [Giant Magellan Telescope Corporation, 251 S. Lake Ave., Suite 300, Pasadena, CA 91101 (United States); Barth, Aaron J. [Department of Physics and Astronomy, University of California at Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697-4575 (United States); Im, Myungshin, E-mail: mkim@kasi.re.kr, E-mail: lho.pku@gmail.com, E-mail: peng@gmto.org, E-mail: barth@uci.edu, E-mail: mim@astro.snu.ac.kr [Department of Physics and Astronomy, Frontier Physics Research Division (FPRD), Seoul National University, Seoul (Korea, Republic of)

    2017-10-01

    We present detailed image analysis of rest-frame optical images of 235 low-redshift ( z ≲ 0.35) Type 1 active galactic nuclei (AGNs) observed with the Hubble Space Telescope . The high-resolution images enable us to perform rigorous two-dimensional image modeling to decouple the luminous central point source from the host galaxy, which, when warranted, is further decomposed into its principal structural components (bulge, bar, and disk). In many cases, care must be taken to account for structural complexities such as spiral arms, tidal features, and overlapping or interacting companion galaxies. We employ Fourier modes to characterize the degree of asymmetry of the light distribution of the stars as a quantitative measure of morphological distortion due to interactions or mergers. We examine the dependence of the physical parameters of the host galaxies on the properties of the AGNs, namely, radio-loudness and the width of the broad emission lines. In accordance with previous studies, narrow-line (H β FWHM ≤ 2000 km s{sup −1}) Type 1 AGNs, in contrast to their broad-line (H β FWHM > 2000 km s{sup −1}) counterparts, are preferentially hosted in later-type, lower-luminosity galaxies, which have a higher incidence of pseudo-bulges, are more frequently barred, and are less morphologically disturbed. This suggests that narrow-line Type 1 AGNs experienced a more quiescent evolutionary history driven primarily by internal secular evolution instead of external dynamical perturbations. The fraction of AGN hosts showing merger signatures is larger for more luminous sources. Radio-loud AGNs generally preferentially live in earlier-type (bulge-dominated), more massive hosts, although a minority of them appear to contain a significant disk component. We do not find convincing evidence for enhanced merger signatures in the radio-loud population.

  20. Bars and spirals in tidal interactions with an ensemble of galaxy mass models

    Science.gov (United States)

    Pettitt, Alex R.; Wadsley, J. W.

    2018-03-01

    We present simulations of the gaseous and stellar material in several different galaxy mass models under the influence of different tidal fly-bys to assess the changes in their bar and spiral morphology. Five different mass models are chosen to represent the variety of rotation curves seen in nature. We find a multitude of different spiral and bar structures can be created, with their properties dependent on the strength of the interaction. We calculate pattern speeds, spiral wind-up rates, bar lengths, and angular momentum exchange to quantify the changes in disc morphology in each scenario. The wind-up rates of the tidal spirals follow the 2:1 resonance very closely for the flat and dark matter-dominated rotation curves, whereas the more baryon-dominated curves tend to wind-up faster, influenced by their inner bars. Clear spurs are seen in most of the tidal spirals, most noticeable in the flat rotation curve models. Bars formed both in isolation and interactions agree well with those seen in real galaxies, with a mixture of `fast' and `slow' rotators. We find no strong correlation between bar length or pattern speed and the interaction strength. Bar formation is, however, accelerated/induced in four out of five of our models. We close by briefly comparing the morphology of our models to real galaxies, easily finding analogues for nearly all simulations presenter here, showing passages of small companions can easily reproduce an ensemble of observed morphologies.

  1. Associating Fast Radio Bursts with Their Host Galaxies

    Science.gov (United States)

    Eftekhari, T.; Berger, E.

    2017-11-01

    The first precise localization of a fast radio burst (FRB) sheds light on the nature of these mysterious bursts and the physical mechanisms that power them. Increasing the sample of FRBs with robust host galaxy associations is the key impetus behind ongoing and upcoming searches and facilities. Here, we quantify the robustness of FRB host galaxy associations as a function of localization area and galaxy apparent magnitude. We also explore the use of FRB dispersion measures to constrain the source redshift, thereby reducing the number of candidate hosts. We use these results to demonstrate that even in the absence of a unique association, a constraint can be placed on the maximum luminosity of a host galaxy as a function of localization and dispersion measure (DM). We find that localizations of ≲ 0.5\\text{'}\\text{'} are required for a chance coincidence probability of ≲ 1 % for dwarf galaxies at z≳ 0.1; if some hosts have luminosities of ˜ {L}\\ast , then localizations of up to ≈ 5\\prime\\prime may suffice at z˜ 0.1. Constraints on the redshift from the DM only marginally improve the association probability unless the DM is low, ≲ 400 pc cm-3. This approach also relies on the determination of galaxy redshifts, which is challenging at z≳ 0.5 if the hosts are dwarf galaxies. Finally, interesting limits on the maximum host luminosity require localizations of ≲ 5\\prime\\prime at z≳ 0.1. Even a few such localizations will explain the nature of FRB progenitors, their possible diversity, and their use as cosmological tools.

  2. What Makes the Family of Barred Disc Galaxies So Rich: Damping Stellar Bars in Spinning Haloes

    Science.gov (United States)

    Collier, Angela; Shlosman, Isaac; Heller, Clayton

    2018-02-01

    We model and analyze the secular evolution of stellar bars in spinning dark matter (DM) haloes with the cosmological spin λ ˜ 0 - 0.09. Using high-resolution stellar and DM numerical simulations, we focus on angular momentum exchange between stellar discs and DM haloes of various axisymmetric shapes — spherical, oblate and prolate. We find that stellar bars experience a diverse evolution which is guided by the ability of parent haloes to absorb angular momentum, J, lost by the disc through the action of gravitational torques, resonant and non-resonant. We confirm that dynamical bar instability is accelerated via resonant J-transfer to the halo. Our main findings relate to the long-term, secular evolution of disc-halo systems: with an increasing λ, bars experience less growth and basically dissolve after they pass through vertical buckling instability. Specifically, with increasing λ, (1) The vertical buckling instability in stellar bars colludes with inability of the inner halo to absorb J — this emerges as the main factor weakening or destroying bars in spinning haloes; (2) Bars lose progressively less J, and their pattern speeds level off; (3) Bars are smaller, and for λ ≳ 0.06 cease their growth completely following buckling; (4) Bars in λ > 0.03 halos have ratio of corotation-to-bar radii, RCR/Rb > 2, and represent so-called slow bars without offset dust lanes. We provide a quantitative analysis of J-transfer in disc-halo systems, and explain the reasons for absence of growth in fast spinning haloes and its observational corollaries. We conclude that stellar bar evolution is substantially more complex than anticipated, and bars are not as resilient as has been considered so far.

  3. Detection of Bars in Galaxies using a Deep Convolutional Neural Network

    Science.gov (United States)

    Abraham, Sheelu; Aniyan, A. K.; Kembhavi, Ajit K.; Philip, N. S.; Vaghmare, Kaustubh

    2018-03-01

    We present an automated method for the detection of bar structure in optical images of galaxies using a deep convolutional neural network which is easy to use and provides good accuracy. In our study we use a sample of 9346 galaxies in the redshift range 0.009-0.2 from the Sloan Digital Sky Survey, which has 3864 barred galaxies, the rest being unbarred. We reach a top precision of 94 per cent in identifying bars in galaxies using the trained network. This accuracy matches the accuracy reached by human experts on the same data without additional information about the images. Since Deep Convolutional Neural Networks can be scaled to handle large volumes of data, the method is expected to have great relevance in an era where astronomy data is rapidly increasing in terms of volume, variety, volatility and velocity along with other V's that characterize big data. With the trained model we have constructed a catalogue of barred galaxies from SDSS and made it available online.

  4. Stellar Populations of Quasar Host Galaxies Using WIYN

    Science.gov (United States)

    Mosby, Gregory; Moravec, E.; Kotulla, R. C.

    2013-06-01

    We now know that most galaxies have supermassive black holes (SMBH) in their centers, and somewhat unexpectedly, there are relationships—such as the M-sigma relation—between the mass of the central black hole and the velocity dispersion of the host galaxy's stellar spheroid (bulge), even though they lie outside the black hole's influence. Galaxy merger models show reasonable evidence for coevolution of the bulge and black hole since the merging process initiates simultaneous growth of the black hole and galaxy by supplying gas to the nucleus for accretion onto the black hole and triggering bursts of star formation. The merging process truncates the growth of both by removing the gas reservoir via feedback from these processes. But recently, it’s been shown that this relation could arise from central limit-like arguments alone. To really judge connections between SMBH and their host, it’s crucial to study these galaxies at the peak of black hole growth—during the quasar phase. Using 3-d spectroscopy methods, namely Sparsepak, an integral field units (IFU) on WIYN, it is possible to successfully recover information about the host galaxy's integrated star formation history that can be used to check merger-induced galaxy evolution predicted by the models. However, it is critical to have a robust and careful analysis of the stellar population modeling. The research presented in this poster focuses on new results from Sparsepak and preliminary WHIRC H-band light profiles of select quasar host galaxies. The stellar populations are derived using a new statistical method called diffusion k-means, and the WHIRC data are analyzed using a Python code written by Ralf Kotulla.

  5. Hydrodynamic effects of nuclear active galaxy winds on host galaxies

    International Nuclear Information System (INIS)

    Schiano, A.V.R.

    1984-01-01

    In order to test the hypothesized existence of a powerful, thermal wind in active galactic nuclei, the hydrodynamic effects of such a wind on a model galactic interstellar medium (ISM) are investigated. The properties of several model ISMs are derived from observations of the Milky Way's ISM and those of nearby spiral and elliptical galaxies. The propagation of the wind into the low density gas component of the ISM is studied using the Kompaneets approximation of a strong explosion in an exponential atmosphere. Flattened gas distributions are shown to experience blow-out of wind gas along the symmetry axis. Next, the interaction of dense, interstellar clouds with the wind is investigated. The stability and mass loss of clouds in the wind are studied and it is proposed that clouds survive the encounter with the wind over large timescales. It is proposed that the narrow emission line regions (NELR) of active galaxies are the result of the interaction of active nuclei photons and a thermal wind on large, interstellar clouds

  6. The blue host galaxy of the red GRB 000418

    DEFF Research Database (Denmark)

    Gorosabel, J.; Klose, S.; Christensen, L.

    2003-01-01

    We report on multi-band (UBVRIZJ(s)K(s)) observations of the host galaxy of the April 18, 2000 gamma-ray burst. The Spectral Energy Distribution (SED) is analysed by fitting empirical and synthetic spectral templates. We find that: (i) the best SED fit is obtained with a starburst template, (ii...... (A(V) = 0.4-0.9 mag), suggesting a homogeneous distribution of the interstellar medium (ISM) in the host galaxy. These findings are supplemented by morphological information from Hubble Space Telescope (HST) imaging: the surface brightness profile is smooth, symmetric and compact with no underlying...

  7. Optical observations of Dwingeloo 1, a nearby barred spiral galaxy behind the Milky Way

    NARCIS (Netherlands)

    Loan, AJ; Maddox, SJ; Lahav, O; Balcells, M; KraanKorteweg, RC; Assendorp, R; Almoznino, E; Brosch, N; Goldberg, E; Ofek, EO

    1996-01-01

    We present new optical observations of the nearby barred spiral galaxy Dwingeloo 1 (Dw1) obtained with the Isaac Newton, William Herschel and Wise telescopes. Dw1 lies at Galactic coordinates (l=138.degrees 52, b=-0.degrees 11) and it is heavily obscured by dust and gas in the Milky Way. We infer

  8. Dark and luminous matter in the NGC 3992 group of galaxies - I. The large barred spiral NGC 3992

    NARCIS (Netherlands)

    Bottema, R; Verheijen, MAW

    Detailed neutral hydrogen observations have been obtained of the large barred spiral galaxy NGC 3992 and its three small companion galaxies, UGC 6923, UGC 6940, and UGC 6969. For the main galaxy, the Hi distribution is regular with a low level radial extension outside the stellar disc. However, at

  9. Simple stellar population modelling of low S/N galaxy spectra and quasar host galaxy applications

    Science.gov (United States)

    Mosby, G.; Tremonti, C. A.; Hooper, E. J.; Wolf, M. J.; Sheinis, A. I.; Richards, J. W.

    2015-02-01

    To study the effect of supermassive black holes (SMBHs) on their host galaxies it is important to study the hosts when the SMBH is near its peak activity. A method to investigate the host galaxies of high luminosity quasars is to obtain optical spectra at positions offset from the nucleus where the relative contribution of the quasar and host is comparable. However, at these extended radii the galaxy surface brightness is often low (20-22 mag arcsec-2) and the resulting spectrum might have such low signal-to-noise ratio (S/N) that it hinders analysis with standard stellar population modelling techniques. To address this problem, we have developed a method that can recover galaxy star formation histories (SFHs) from rest-frame optical spectra with S/N ˜ 5 Å-1. This method uses the statistical technique diffusion k-means to tailor the stellar population modelling basis set. Our diffusion k-means minimal basis set, composed of four broad age bins, is successful in recovering a range of galaxy SFHs. Additionally, using an analytic prescription for seeing conditions, we are able to simultaneously model scattered quasar light and the SFH of quasar host galaxies (QHGs). We use synthetic data to compare results of our novel method with previous techniques. We also present the modelling results on a previously published QHG and show that galaxy properties recovered from a diffusion k-means basis set are less sensitive to noise added to this QHG spectrum. Our new method has a clear advantage in recovering information from QHGs and could also be applied to the analysis of other low S/N galaxy spectra such as those typically obtained for high redshift objects or integral field spectroscopic surveys.

  10. The Physical Properties and Kinematics of Molecular Gas in a Barred Galaxy NGC 2903

    Science.gov (United States)

    Xu, Zizheng; Ueda, Junko; Petitpas, Glen

    2018-01-01

    Barred spiral galaxies are ideal sources for studying the relation between star formation and kpc-scale galactic dynamics. The non-circular motions of gas are induced by the non-axisymmetric bar potential. Theoretical studies and numerical simulations have shown that these motions pile up the gas along the leading side of the bar and induce shock waves and/or shear motion. It is expected that the physical properties of molecular gas change in such an environment. The shock wave and shear motion make molecular clouds break down, which eventually suppresses the star-formation activities. In order to better understand star formation in barred galaxies, it is important to investigate the physical properties and kinematics of the molecular gas that is the fuel of stars. We have conducted the CO (2-1) observations of a nearby barred galaxy NGC 2903 using SMA. We compare the distribution and kinematics of cold molecular gas with those of stellar components and ionized gas in order to investigate the relation between the properties of molecular gas and star formation. We also make the CO (2-1)/CO (1-0) line ratio map using the archival CO (1-0) data obtained with BIMA. This enables us investigate the excitation condition of the CO molecule with twice higher angular resolution compared to previous studies. In this presentation, we discuss the distribution and kinematics of molecular gas, and excitation condition in NGC 2903.

  11. INTRINSIC ELLIPTICITY CORRELATION OF SDSS LUMINOUS RED GALAXIES AND MISALIGNMENT WITH THEIR HOST DARK MATTER HALOS

    International Nuclear Information System (INIS)

    Okumura, Teppei; Jing, Y. P.; Li Cheng

    2009-01-01

    We investigate the orientation correlation of giant elliptical galaxies by measuring the intrinsic ellipticity correlation function of 83,773 luminous red galaxies (LRGs) at redshifts 0.16-0.47 from the Sloan Digital Sky Survey. We have accurately determined the correlation up to 30 h -1 Mpc. Luminosity dependence of the ellipticity correlation is also detected although the error bars are large, while no evidence is found for its redshift evolution between z = 0.2 and z = 0.4. Then we use a cosmological N-body simulation to examine misalignment between the central LRGs and their parent dark matter halos. Central and satellite galaxies are assigned to simulated halos by employing a halo occupation distribution model for the LRGs. The ellipticity correlation is predicted to have the same shape as, but an amplitude about four times higher than, our observation if the central LRGs are perfectly aligned with their host halos. This indicates that the central LRG galaxies are preferentially but not perfectly aligned with their host halos. With the assumption that there is a misalignment angle between a central LRG and its host halo which follows a Gaussian distribution with a zero mean and a width σ θ , we obtain a tight constraint on the misalignment parameter, σ θ = 35.4 +4.0 -3.3 deg. This type of intrinsic ellipticity correlation, if not corrected, can lead to contamination at 5% level to the shear power spectrum in weak lensing surveys of limiting magnitude R AB = 24.5 if the source central galaxies follow the same misalignment distribution as the LRGs.

  12. Statistical Properties of Gamma-Ray Burst Host Galaxies Jie-Min ...

    Indian Academy of Sciences (India)

    Statistical Properties of Gamma-Ray Burst Host Galaxies. Jie-Min Chen1, Jin Zhang2,3, ... of GRB host galaxies and explore possible correlations between these properties. We also investigate possible cosmic ... hydrogen column density for the GRB host galaxies in our sample. 6.295. The stellar masses are mainly in the ...

  13. Statistical Properties of Gamma-Ray Burst Host Galaxies Jie-Min ...

    Indian Academy of Sciences (India)

    Abstract. A statistical analysis of gamma-ray burst host galaxies is pre- sented and a clear metallicity-stellar mass relation is found in our sample. A trend that a more massive host galaxy tends to have a higher star- formation rate is also found. No correlation is found between AV and NH. GRB host galaxies at a higher ...

  14. Bar formation in disk galaxies, and the normalized angular momentum of the bulge

    Energy Technology Data Exchange (ETDEWEB)

    Zasov, A.V.

    1985-09-01

    In 1971 Polyachenko et al. suggested that the spheroidal bulge in a spiral galaxy would retain a biaxial shape unless its normalized angular momentum, defined as M = KM/sub b//sup -5/3/ (K is the ordinary angular momentum and M/sub b/ the mass of the bulge), exceeds some critical value; in that event a triaxial ellipsoid: a bar: would develop. This proposal is in fact consistent with bulge rotational velocities observed in disk-type systems. The bar presumably represents a bulge component having a high M value.

  15. Revisiting The First Galaxies: The effects of Population III stars on their host galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Muratov, Alexander L. [U. Michigan, Dept. Astron.; Gnedin, Oleg Y. [U. Michigan, Dept. Astron.; Gnedin, Nickolay Y. [Chicago U., Astron. Astrophys. Ctr.; Zemp, Marcel [Beijing, KITPC

    2013-07-12

    We revisit the formation and evolution of the first galaxies using new hydrodynamic cosmological simulations with the adaptive refinement tree code. Our simulations feature a recently developed model for H2 formation and dissociation, and a star formation recipe that is based on molecular rather than atomic gas. Here, we develop and implement a recipe for the formation of metal-free Population III (Pop III) stars in galaxy-scale simulations that resolve primordial clouds with sufficiently high density. We base our recipe on the results of prior zoom-in simulations that resolved the protostellar collapse in pre-galactic objects. We find the epoch during which Pop III stars dominated the energy and metal budget of the first galaxies to be short-lived. Galaxies that host Pop III stars do not retain dynamical signatures of their thermal and radiative feedback for more than 108 years after the lives of the stars end in pair-instability supernovae, even when we consider the maximum reasonable efficiency of the feedback. Though metals ejected by the supernovae can travel well beyond the virial radius of the host galaxy, they typically begin to fall back quickly, and do not enrich a large fraction of the intergalactic medium. Galaxies with a total mass in excess of 3 × 106 M re-accrete most of their baryons and transition to metal-enriched Pop II star formation.

  16. The dependence of bar frequency on galaxy mass, colour, and gas content - and angular resolution - in the local universe

    Science.gov (United States)

    Erwin, Peter

    2018-03-01

    I use distance- and mass-limited subsamples of the Spitzer Survey of Stellar Structure in Galaxies (S4G) to investigate how the presence of bars in spiral galaxies depends on mass, colour, and gas content and whether large, Sloan Digital Sky Survey (SDSS)-based investigations of bar frequencies agree with local data. Bar frequency reaches a maximum of fbar ≈ 0.70 at M⋆ ˜ 109.7M⊙, declining to both lower and higher masses. It is roughly constant over a wide range of colours (g - r ≈ 0.1-0.8) and atomic gas fractions (log (M_{H I}/ M_{\\star }) ≈ -2.5 to 1). Bars are thus as common in blue, gas-rich galaxies are they are in red, gas-poor galaxies. This is in sharp contrast to many SDSS-based studies of z ˜ 0.01-0.1 galaxies, which report fbar increasing strongly to higher masses (from M⋆ ˜ 1010 to 1011M⊙), redder colours, and lower gas fractions. The contradiction can be explained if SDSS-based studies preferentially miss bars in, and underestimate the bar fraction for, lower mass (bluer, gas-rich) galaxies due to poor spatial resolution and the correlation between bar size and stellar mass. Simulations of SDSS-style observations using the S4G galaxies as a parent sample, and assuming that bars below a threshold angular size of twice the point spread function full width at half-maximum cannot be identified, successfully reproduce typical SDSS fbar trends for stellar mass and gas mass ratio. Similar considerations may affect high-redshift studies, especially if bars grow in length over cosmic time; simulations suggest that high-redshift bar fractions may thus be systematically underestimated.

  17. THE BULGELESS SEYFERT/LINER GALAXY NGC 3367: DISK, BAR, LOPSIDEDNESS, AND ENVIRONMENT

    International Nuclear Information System (INIS)

    Hernández-Toledo, H. M.; Cano-Díaz, M.; Valenzuela, O.; García-Barreto, J. A; Moreno-Díaz, E.; Puerari, I.; Bravo-Alfaro, H.

    2011-01-01

    NGC 3367 is a nearby isolated active galaxy that shows a radio jet, a strong bar, and evidence of lopsidedness. We present a quantitative analysis of the stellar and gaseous structure of the galaxy disk and search for evidence of recent interaction. Our study is based on new UBVRI Hα and JHK images and on archive Hα Fabry-Perot and H I Very Large Array data. From a coupled one-dimensional/two-dimensional GALFIT bulge/bar/disk decomposition a (B/D ∼ 0.07-0.1) exponential pseudobulge is inferred in all the observed bands. A near-infrared (NIR) estimate of the bar strength Q max T (R) = 0.44 places NGC 3367 bar among the strongest ones. The asymmetry properties were studied using (1) the optical and NIR concentration-asymmetry-clumpiness indices, (2) the stellar (NIR) and gaseous (Hα, H I) A 1 Fourier mode amplitudes, and (3) the H I-integrated profile and H I mean intensity distribution. While the average stellar component shows asymmetry values close to the average found in the local universe for isolated galaxies, the young stellar component and gas values are largely decoupled showing significantly larger A 1 mode amplitudes suggesting that the gas has been recently perturbed and placing NGC 3367 in a global starburst phase. NGC 3367 is devoid of H I gas in the central regions where a significant amount of molecular CO gas exists instead. Our search for (1) faint stellar structures in the outer regions (up to μ R ∼ 26 mag arcsec –2 ), (2) (Hα) star-forming satellite galaxies, and (3) regions with different colors (stellar populations) along the disk all failed. Such an absence is interpreted by using results from recent numerical simulations to constrain either a possible tidal event with an LMC like galaxy to some dynamical times in the past or a very low mass but perhaps gas rich recent encounter. We conclude that a cold flow accretion mode (gas and small/dark galaxies) may be responsible for the nuclear activity and peculiar (young stars and gas

  18. GRB 990712 optical decay: indication of bright host galaxy.

    Science.gov (United States)

    Hjorth, J.; Courbin, F.; Cuadra, J.; Minniti, D.

    We have obtained a 5-min R-band exposure of the optical afterglow of GRB 990712 (Frontera, GCN #385; Bakos et al., GCN #387) with the ESO 3.5-m NTT on 16.403 July 1999 UT. We detect an unresolved (seeing FWHM = 1.8") object at RA (2000) = 22 31 53.03, Dec (2000) = -73 24 28.3 (with a positional uncertainty of +- 0.6" relative to the USNO-A2.0 system), consistent with the position of the bright decaying source discovered by Bakos et al. (IAUC 7225). We have tied our photometry to the PLANET photometric zeropoint (K. Sahu, personal communication) and find that the object has continued to fade to R = 21.48 +- 0.02 (systematic) +- 0.05 (random). The combined SAAO data (Bakos et al., IAUC 7225) and NTT data indicate that the light curve is leveling off relative to a power law decline. Assuming that the light curve can be modeled as the combined effects of a power law decline of the OT and a constant contribution from the host galaxy we find an OT decay slope of -0.81 (i.e. a rather slow decay) and a bright host galaxy with R = 22.0. Such a bright host galaxy would be consistent with its fairly low redshift (z = 0.43) and would possibly even account for the prominent emission lines seen in the VLT spectrum (Galama et al., GCN #388). We caution however that the hypothesis of a bright host galaxy is based on just a few data points. To test this hypothesis continued monitoring of the system is therefore urged. The NTT image and the R-band light curve are posted at http://www.astro.ku.dk/~jens/grb990712/ .

  19. STAR FORMATION PROPERTIES IN BARRED GALAXIES (SFB). I. ULTRAVIOLET TO INFRARED IMAGING AND SPECTROSCOPIC STUDIES OF NGC 7479

    International Nuclear Information System (INIS)

    Zhou Zhimin; Meng Xianmin; Wu Hong; Cao Chen

    2011-01-01

    Large-scale bars and minor mergers are important drivers for the secular evolution of galaxies. Based on ground-based optical images and spectra as well as ultraviolet data from the Galaxy Evolution Explorer and infrared data from the Spitzer Space Telescope, we present a multi-wavelength study of star formation properties in the barred galaxy NGC 7479, which also has obvious features of a minor merger. Using various tracers of star formation, we find that under the effects of both a stellar bar and a minor merger, star formation activity mainly takes place along the galactic bar and arms, while the star formation rate changes from the bar to the disk. With the help of spectral synthesis, we find that strong star formation took place in the bar region about 100 Myr ago, and the stellar bar might have been ∼10 Gyr old. By comparing our results with the secular evolutionary scenario from Jogee et al., we suggest that NGC 7479 is possibly in a transitional stage of secular evolution at present, and it may eventually become an earlier type galaxy or a luminous infrared galaxy. We also note that the probable minor merger event happened recently in NGC 7479, and we find two candidates for minor merger remnants.

  20. SDSS IV MaNGA - Properties of AGN Host Galaxies

    Science.gov (United States)

    Sánchez, S. F.; Avila-Reese, V.; Hernandez-Toledo, H.; Cortes-Suárez, E.; Rodríguez-Puebla, A.; Ibarra-Medel, H.; Cano-Díaz, M.; Barrera-Ballesteros, J. K.; Negrete, C. A.; Calette, A. R.; de Lorenzo-Cáceres, A.; Ortega-Minakata, R. A.; Aquino, E.; Valenzuela, O.; Clemente, J. C.; Storchi-Bergmann, T.; Riffel, R.; Schimoia, J.; Riffel, R. A.; Rembold, S. B.; Brownstein, J. R.; Pan, K.; Yates, R.; Mallmann, N.; Bitsakis, T.

    2018-04-01

    We present the characterization of the main properties of a sample of 98 AGN host galaxies, both type-II and type-I, in comparison with those of ≍2700 non-active galaxies observed by the MaNGA survey. We found that AGN hosts are morphologically early-type or early-spirals. AGN hosts are, on average, more massive, more compact, more centrally peaked and more pressure-supported systems. They are located in the intermediate/transition region between starforming and non-star-forming galaxies (i.e., the so-called green valley). We consider that they are in the process of halting/quenching the star formation. The analysis of the radial distributions of different properties shows that the quenching happens from inside-out involving both a decrease of the effciency of the star formation and a deficit of molecular gas. The data-products of the current analysis are distributed as a Value Added Catalog within the SDSS-DR14.

  1. Starburst-driven Superwinds in Quasar Host Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Barthel, Peter; Podigachoski, Pece [Kapteyn Astronomical Institute, University of Groningen, Groningen (Netherlands); Wilkes, Belinda [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Haas, Martin, E-mail: pdb@astro.rug.nl, E-mail: podigachoski@astro.rug.nl [Astronomisches Institut, Ruhr Universität, Bochum (Germany)

    2017-07-01

    During the past five decades astronomers have been puzzled by the presence of strong absorption features including metal lines, observed in the optical and ultraviolet spectra of quasars, signaling inflowing and outflowing gas winds with relative velocities up to several thousands of km s{sup −1}. In particular, the location of these winds—close to the quasar, further out in its host galaxy, or in its direct environment—and the possible impact on their surroundings have been issues of intense discussion and uncertainty. Using our Herschel Space Observatory data, we report a tendency for this so-called associated metal absorption to occur along with prodigious star formation in the quasar host galaxy, indicating that the two phenomena are likely to be interrelated, that the gas winds likely occur on the kiloparsec scale and would then have a strong impact on the interstellar medium of the galaxy. This correlation moreover would imply that the unusually high cold dust luminosities in these quasars are connected with ongoing star formation. Given that we find no correlation with the AGN strength, the wind feedback that we establish in these radio-loud objects is most likely associated with their host star formation rather than with their black hole accretion.

  2. ARE SOME MILKY WAY GLOBULAR CLUSTERS HOSTED BY UNDISCOVERED GALAXIES?

    Energy Technology Data Exchange (ETDEWEB)

    Zaritsky, Dennis [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Crnojević, Denija; Sand, David J., E-mail: dennis.zaritsky@gmail.com [Physics Department, Texas Tech University, Box 41051, Lubbock, TX 79409 (United States)

    2016-07-20

    The confirmation of a globular cluster (GC) in the recently discovered ultrafaint galaxy Eridanus II (Eri II) motivated us to examine the question posed in the title. After estimating the halo mass of Eri II using a published stellar mass—halo mass relation, the one GC in this galaxy supports extending the relationship between the number of GCs hosted by a galaxy and the galaxy’s total mass about two orders of magnitude in stellar mass below the previous limit. For this empirically determined specific frequency of between 0.06 and 0.39 GCs per 10{sup 9} M {sub ⊙} of total mass, the surviving Milky Way (MW) subhalos with masses smaller than 10{sup 10} M {sub ⊙} could host as many as 5–31 GCs, broadly consistent with the actual population of outer halo MW GCs, although matching the radial distribution in detail remains a challenge. Using a subhalo mass function from published high-resolution numerical simulations and a Poissonian model for populating those halos with the aforementioned empirically constrained frequency, we find that about 90% of these GCs lie in lower-mass subhalos than that of Eri II. From what we know about the stellar mass–halo mass function, the subhalo mass function, and the mass-normalized GC specific frequency, we conclude that some of the MW’s outer halo GCs are likely to be hosted by undetected subhalos with extremely modest stellar populations.

  3. Starburst-driven Superwinds in Quasar Host Galaxies

    International Nuclear Information System (INIS)

    Barthel, Peter; Podigachoski, Pece; Wilkes, Belinda; Haas, Martin

    2017-01-01

    During the past five decades astronomers have been puzzled by the presence of strong absorption features including metal lines, observed in the optical and ultraviolet spectra of quasars, signaling inflowing and outflowing gas winds with relative velocities up to several thousands of km s −1 . In particular, the location of these winds—close to the quasar, further out in its host galaxy, or in its direct environment—and the possible impact on their surroundings have been issues of intense discussion and uncertainty. Using our Herschel Space Observatory data, we report a tendency for this so-called associated metal absorption to occur along with prodigious star formation in the quasar host galaxy, indicating that the two phenomena are likely to be interrelated, that the gas winds likely occur on the kiloparsec scale and would then have a strong impact on the interstellar medium of the galaxy. This correlation moreover would imply that the unusually high cold dust luminosities in these quasars are connected with ongoing star formation. Given that we find no correlation with the AGN strength, the wind feedback that we establish in these radio-loud objects is most likely associated with their host star formation rather than with their black hole accretion.

  4. Characterizing the Supernova Host Galaxy Population with ASAS-SN

    Science.gov (United States)

    Brown, Jonathan; ASAS-SN Team

    2018-01-01

    The goal of the All-Sky Automated Survey for Supernovae (ASAS-SN) is to provide the astronomical community with a complete record of the optically accessible night sky. ASAS-SN uses a global array of telescopes to monitor the entire sky on a nightly cadence. Due to the nearby volume probed by ASAS-SN, our survey excels at discovering bright transient events. The events we discover can be studied in great detail and monitored well into the late phases of evolution with only modest observational resources. ASAS-SN has discovered a plethora of interesting transient events, and has also amassed a large sample of supernovae (SNe). Not only are the statistical properties of these SNe interesting in their own right, but the galaxies that host these events are also of great scientific interest. I will present the initial results of our SNe host galaxy census, and highlight some systems that would have been missed by traditional SN surveys. Finally I will discuss how this dataset will be used to improve our understanding of the SNe-host galaxy connection.

  5. Orbital and escape dynamics in barred galaxies - I. The 2D system

    Science.gov (United States)

    Jung, Christof; Zotos, Euaggelos E.

    2016-04-01

    In this paper, we use the two-dimensional version of a new analytical gravitational model in order to explore the orbital as well as the escape dynamics of the stars in a barred galaxy composed of a spherically symmetric central nucleus, a bar, a flat disc and a dark matter halo component. A thorough numerical investigation is conducted for distinguishing between bounded and escaping motion. Furthermore, bounded orbits are further classified into non-escaping regular and trapped chaotic using the Smaller ALingment Index method. Our aim is to determine the basins of escape through the two symmetrical escape channels around the Lagrange points L2 and L3 and also to relate them with the corresponding distribution of the escape rates of the orbits. We integrate initial conditions of orbits in several types of planes so as to obtain a more complete view of the overall orbital properties of the dynamical system. We also present evidence that the unstable manifolds which guide the orbits in and out the interior region are directly related with the formation of spiral and ring stellar structures observed in barred galaxies. In particular, we examine how the bar's semimajor axis determines the resulting morphologies. Our numerical simulations indicate that weak barred structures favour the formation of R1 rings or R_1^' } pseudo-rings, while strong bars on the other hand, give rise to R1R2 and open spiral morphologies. Our results are compared with earlier related work. The escape dynamics and the properties of the manifolds of the full three-dimensional galactic system will be given in an accompanying paper.

  6. The HST/ACS Coma Cluster Survey. VIII. Barred Disk Galaxies in the Core of the Coma Cluster

    NARCIS (Netherlands)

    Marinova, Irina; Jogee, Shardha; Weinzirl, Tim; Erwin, Peter; Trentham, Neil; Ferguson, Henry C.; Hammer, Derek; den Brok, Mark; Graham, Alister W.; Carter, David; Balcells, Marc; Goudfrooij, Paul; Guzmán, Rafael; Hoyos, Carlos; Mobasher, Bahram; Mouhcine, Mustapha; Peletier, Reynier F.; Peng, Eric W.; Verdoes Kleijn, Gijs

    We use high-resolution (~0farcs1) F814W Advanced Camera for Surveys (ACS) images from the Hubble Space Telescope ACS Treasury survey of the Coma cluster at z ~ 0.02 to study bars in massive disk galaxies (S0s), as well as low-mass dwarf galaxies in the core of the Coma cluster, the densest

  7. The HST/ACS Coma Cluster Survey : VIII. Barred Disk Galaxies in the Core of the Coma Cluster

    NARCIS (Netherlands)

    Marinova, Irina; Jogee, Shardha; Weinzirl, Tim; Erwin, Peter; Trentham, Neil; Ferguson, Henry C.; Hammer, Derek; den Brok, Mark; Graham, Alister W.; Carter, David; Balcells, Marc; Goudfrooij, Paul; Guzman, Rafael; Hoyos, Carlos; Mobasher, Bahram; Mouhcine, Mustapha; Peletier, Reynier F.; Peng, Eric W.; Kleijn, Gijs V.

    2012-01-01

    We use high-resolution (similar to 0.'' 1) F814W Advanced Camera for Surveys (ACS) images from the Hubble Space Telescope ACS Treasury survey of the Coma cluster at z similar to 0.02 to study bars in massive disk galaxies (S0s), as well as low-mass dwarf galaxies in the core of the Coma cluster, the

  8. Luminous and Obscured Quasars and Their Host Galaxies

    Directory of Open Access Journals (Sweden)

    Agnese Del Moro

    2018-01-01

    Full Text Available The most heavily-obscured, luminous quasars might represent a specific phase of the evolution of the actively accreting supermassive black holes and their host galaxies, possibly related to mergers. We investigated a sample of the most luminous quasars at z ≈ 1 − 3 in the GOODS fields, selected in the mid-infrared band through detailed spectral energy distribution (SED decomposition. The vast majority of these quasars (~80% are obscured in the X-ray band and ~30% of them to such an extent, that they are undetected in some of the deepest (2 and 4 Ms Chandra X-ray data. Although no clear relation is found between the star-formation rate of the host galaxies and the X-ray obscuration, we find a higher incidence of heavily-obscured quasars in disturbed/merging galaxies compared to the unobscured ones, thus possibly representing an earlier stage of evolution, after which the system is relaxing and becoming unobscured.

  9. MOLECULAR GAS IN z ∼ 6 QUASAR HOST GALAXIES

    International Nuclear Information System (INIS)

    Wang Ran; Carilli, Chris L.; Wagg, Jeff; Neri, R.; Cox, Pierre; Riechers, D. A.; Walter, Fabian; Bertoldi, Frank; Menten, Karl M.; Omont, Alain; Fan Xiaohui

    2010-01-01

    We report our new observations of redshifted carbon monoxide emission from six z ∼ 6 quasars, using the IRAM Plateau de Bure Interferometer. CO (6-5) or (5-4) line emission was detected in all six sources. Together with two other previous CO detections, these observations provide unique constraints on the molecular gas emission properties in these quasar systems close to the end of the cosmic re-ionization. Complementary results are also presented for low-J CO lines observed at the Green Bank Telescope and the Very Large Array, and dust continuum from five of these sources with the SHARC-II bolometer camera at the Caltech Submillimeter Observatory. We then present a study of the molecular gas properties in our combined sample of eight CO-detected quasars at z ∼ 6. The detections of high-order CO line emission in these objects indicates the presence of highly excited molecular gas, with estimated masses on the order of 10 10 M sun within the quasar host galaxies. No significant difference is found in the gas mass and CO line width distributions between our z ∼ 6 quasars and samples of CO-detected 1.4 ≤ z ≤ 5 quasars and submillimeter galaxies. Most of the CO-detected quasars at z ∼ 6 follow the far-infrared-CO luminosity relationship defined by actively star-forming galaxies at low and high redshifts. This suggests that ongoing star formation in their hosts contributes significantly to the dust heating at FIR wavelengths. The result is consistent with the picture of galaxy formation co-eval with supermassive black hole (SMBH) accretion in the earliest quasar-host systems. We investigate the black hole-bulge relationships of our quasar sample, using the CO dynamics as a tracer for the dynamical mass of the quasar host. The median estimated black hole-bulge mass ratio is about 15 times higher than the present-day value of ∼0.0014. This places important constraints on the formation and evolution of the most massive SMBH-spheroidal host systems at the

  10. The Influence of Host Galaxies in Type Ia Supernova Cosmology

    Science.gov (United States)

    Uddin, Syed A.; Mould, Jeremy; Lidman, Chris; Ruhlmann-Kleider, Vanina; Zhang, Bonnie R.

    2017-10-01

    We use a sample of 1338 spectroscopically confirmed and photometrically classified Type Ia supernovae (SNe Ia) sourced from Carnegie Supernova Project, Center for Astrophysics Supernova Survey, Sloan Digital Sky Survey-II, and SuperNova Legacy Survey SN samples to examine the relationships between SNe Ia and the galaxies that host them. Our results provide confirmation with improved statistical significance that SNe Ia, after standardization, are on average more luminous in massive hosts (significance >5σ), and decline more rapidly in massive hosts (significance >9σ) and in hosts with low specific star formation rates (significance >8σ). We study the variation of these relationships with redshift and detect no evolution. We split SNe Ia into pairs of subsets that are based on the properties of the hosts and fit cosmological models to each subset. Including both systematic and statistical uncertainties, we do not find any significant shift in the best-fit cosmological parameters between the subsets. Among different SN Ia subsets, we find that SNe Ia in hosts with high specific star formation rates have the least intrinsic scatter (σ int = 0.08 ± 0.01) in luminosity after standardization.

  11. Simple Stellar Population Modeling of Quasar Host Galaxies with Diffusion K-Means Test Results

    Science.gov (United States)

    Mosby, Gregory; Moravec, E. A.; Tremonti, C. A.; Wolf, M. J.

    2013-01-01

    In the last decade, the correlation of the masses of supermassive black holes (SMBHs) and their host galaxy stellar spheroid velocity dispersions (the M-sigma relation) was greeted as clear evidence for the co-evolution of host galaxies and their SMBHs. However, studies in the last five years have posited that this relation could arise from central-limit properties of hierarchical formation alone. To address the question of whether and how often the SMBHs evolve with their host galaxies, it is necessary to look at galaxies whose SMBHs are actively growing—quasars—and determine the host galaxy properties. The central nuclei of quasar host galaxies complicate this type of study because their high luminosity tends to wash out their host galaxies. But, by using 3-D spectroscopy with the integral field unit (IFU) Sparsepak on the WIYN telescope, we have shown that the quasar light can be mostly isolated to one fiber in order to obtain the spectra of the quasar and the host galaxy concurrently. We can then model simultaneously the scattered quasar light and the stellar populations in the host galaxy fiber using a new simple stellar population (SSP) modeling method called diffusion k-means (DFK). The objectives of the research presented in this poster are to model synthetic quasar host galaxies using a DFK basis and a more traditional basis, compare the accuracy of both modeling methods, and test the affects of various prescriptions for masking the quasar lines in the host galaxy fiber. We present results from our SSP modeling and Markov Chain Monte Carlo (MCMC) results for DFK and traditional modeling schemes using synthetic data. By determining and then using the more robust stellar population modeling method, we can more confidently study quasar host galaxies to answer remaining questions in galaxy evolution. This work was partially supported by a National Science Foundation Graduate Fellowship (NSF Grant DGE-0718123) and through the NSF's REU program (NSF Award

  12. The host galaxy of a fast radio burst.

    Science.gov (United States)

    Keane, E F; Johnston, S; Bhandari, S; Barr, E; Bhat, N D R; Burgay, M; Caleb, M; Flynn, C; Jameson, A; Kramer, M; Petroff, E; Possenti, A; van Straten, W; Bailes, M; Burke-Spolaor, S; Eatough, R P; Stappers, B W; Totani, T; Honma, M; Furusawa, H; Hattori, T; Morokuma, T; Niino, Y; Sugai, H; Terai, T; Tominaga, N; Yamasaki, S; Yasuda, N; Allen, R; Cooke, J; Jencson, J; Kasliwal, M M; Kaplan, D L; Tingay, S J; Williams, A; Wayth, R; Chandra, P; Perrodin, D; Berezina, M; Mickaliger, M; Bassa, C

    2016-02-25

    In recent years, millisecond-duration radio signals originating in distant galaxies appear to have been discovered in the so-called fast radio bursts. These signals are dispersed according to a precise physical law and this dispersion is a key observable quantity, which, in tandem with a redshift measurement, can be used for fundamental physical investigations. Every fast radio burst has a dispersion measurement, but none before now have had a redshift measurement, because of the difficulty in pinpointing their celestial coordinates. Here we report the discovery of a fast radio burst and the identification of a fading radio transient lasting ~6 days after the event, which we use to identify the host galaxy; we measure the galaxy's redshift to be z = 0.492 ± 0.008. The dispersion measure and redshift, in combination, provide a direct measurement of the cosmic density of ionized baryons in the intergalactic medium of ΩIGM = 4.9 ± 1.3 per cent, in agreement with the expectation from the Wilkinson Microwave Anisotropy Probe, and including all of the so-called 'missing baryons'. The ~6-day radio transient is largely consistent with the radio afterglow of a short γ-ray burst, and its existence and timescale do not support progenitor models such as giant pulses from pulsars, and supernovae. This contrasts with the interpretation of another recently discovered fast radio burst, suggesting that there are at least two classes of bursts.

  13. HOST GALAXIES OF TYPE Ia SUPERNOVAE FROM THE NEARBY SUPERNOVA FACTORY

    International Nuclear Information System (INIS)

    Childress, M.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Hsiao, E. Y.; Kim, A. G.; Loken, S.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Chotard, N.; Copin, Y.; Gangler, E.

    2013-01-01

    We present photometric and spectroscopic observations of galaxies hosting Type Ia supernovae (SNe Ia) observed by the Nearby Supernova Factory. Combining Galaxy Evolution Explorer (GALEX) UV data with optical and near-infrared photometry, we employ stellar population synthesis techniques to measure SN Ia host galaxy stellar masses, star formation rates (SFRs), and reddening due to dust. We reinforce the key role of GALEX UV data in deriving accurate estimates of galaxy SFRs and dust extinction. Optical spectra of SN Ia host galaxies are fitted simultaneously for their stellar continua and emission lines fluxes, from which we derive high-precision redshifts, gas-phase metallicities, and Hα-based SFRs. With these data we show that SN Ia host galaxies present tight agreement with the fiducial galaxy mass-metallicity relation from Sloan Digital Sky Survey (SDSS) for stellar masses log(M * /M ☉ ) > 8.5 where the relation is well defined. The star formation activity of SN Ia host galaxies is consistent with a sample of comparable SDSS field galaxies, though this comparison is limited by systematic uncertainties in SFR measurements. Our analysis indicates that SN Ia host galaxies are, on average, typical representatives of normal field galaxies.

  14. Supernovae and their host galaxies - V. The vertical distribution of supernovae in disc galaxies

    Science.gov (United States)

    Hakobyan, A. A.; Barkhudaryan, L. V.; Karapetyan, A. G.; Mamon, G. A.; Kunth, D.; Adibekyan, V.; Aramyan, L. S.; Petrosian, A. R.; Turatto, M.

    2017-10-01

    We present an analysis of the height distributions of the different types of supernovae (SNe) from the plane of their host galaxies. We use a well-defined sample of 102 nearby SNe appearing inside high-inclined (I ≥ 85°), morphologically non-disturbed S0-Sd host galaxies from the Sloan Digital Sky Survey. For the first time, we show that in all the subsamples of spirals, the vertical distribution of core-collapse (CC) SNe is about twice closer to the plane of the host disc than the distribution of SNe Ia. In Sb-Sc hosts, the exponential scale height of CC SNe is consistent with those of the younger stellar population in the Milky Way (MW) thin disc, while the scale height of SNe Ia is consistent with those of the old population in the MW thick disc. We show that the ratio of scale lengths to scale heights of the distribution of CC SNe is consistent with those of the resolved young stars with ages from ˜10 up to ˜100 Myr in nearby edge-on galaxies and the unresolved stellar population of extragalactic thin discs. The corresponding ratio for SNe Ia is consistent with the same ratios of the two populations of resolved stars with ages from a few 100 Myr up to a few Gyr and from a few Gyr up to ˜10 Gyr, as well as with the unresolved population of the thick disc. These results can be explained considering the age-scale height relation of the distribution of stellar population and the mean age difference between Type Ia and CC SNe progenitors.

  15. The middle infrared properties of OH megamaser host galaxies

    Science.gov (United States)

    Zhang, J. S.; Wang, J. Z.; Di, G. X.; Zhu, Q. F.; Guo, Q.; Wang, J.

    2014-10-01

    We compiled all 119 OH maser galaxies (110 out of them are megamasers, i.e., LOH> 10 L⊙) published so far and cross-identified these OH masers with the Wide-Field Infrared Survey Explorer (WISE) catalog, to investigate the middle infrared (MIR) properties of OH maser galaxies. The WISE magnitude data at the 3.4, 4.6, 12 and 22 μm (W1 to W4) are collected for the OH maser sample and one control sample, which are non-detection sources. The color-color diagrams show that both OH megamaser (OHM) and non-OHM (ultra)luminous infrared galaxies ((U)LIRGs) are far away from the single blackbody model line and many of them can follow the path described by the power-law model. The active galaxy nuclei (AGN) fraction is about ~40% for both OHM and non-OHM (U)LIRGs, according to the AGN criteria W1 - W2 ≥ 0.8. Among the Arecibo survey sample, OHM sources tend to have a lower luminosity at short MIR wavelengths (e.g., 3.4 μm and 4.6 μm) than that of non-OHM sources, which should come from the low OHM fraction among the survey sample with large 3.4 μm and 4.6 μm luminosity. The OHM fraction tends to increase with cooler MIR colors (larger F22 μm/F3.4 μm). These may be good for sample selection when searching OH megamasers, such as excluding extreme luminous sources at short MIR wavelengths, choosing sources with cooler MIR colors. In the case of the power-law model, we derived the spectral indices for our samples. For the Arecibo survey sample, OHM (U)LIRGs tend to have larger spectral index α22-12 than non-OHM sources, which agrees with previous results. One significant correlation exists between the WISE infrared luminosity at 22μm and the color [W1]-[W4] for the Arecibo OHM hosts. These clues should provide suitable constraints on the sample selection for OH megamaser surveys by future advanced telescopes (e.g., FAST). In addition, the correlation of maser luminosity and the MIR luminosity of maser hosts tends to be non-significant, which may indirectly support

  16. The host galaxy and optical light curve of the gamma-ray burst GRB 980703

    DEFF Research Database (Denmark)

    Holland, S.; Fynbo, J.P.U.; Hjorth, J.

    2001-01-01

    980703 with any special features in the host. The host galaxy appears to be a typical example of a compact star forming galaxy similar to those found in the Hubble Deep Field North. The R-band light curve of the optical afterglow associated with this gamma-ray burst is consistent with a single power...

  17. Host Galaxy Spectra and Consequences for SN Typing from the SDSS SN Survey

    Energy Technology Data Exchange (ETDEWEB)

    Olmstead, Matthew D.; Brown, Peter J.; Sako, Masao; Bassett, Bruce; Bizyaev, Dmitry; Brinkmann, J.; Brownstein, Joel R.; Brewington, Howard; Campbell, Heather; D’Andrea, Chris B.; Dawson, Kyle S.; Ebelke, Garrett L.; Frieman, Joshua A.; Galbany, Lluís; Garnavich, Peter; Gupta, Ravi R.; Hlozek, Renee; Jha, Saurabh W.; Kunz, Martin; Lampeitl, Hubert; Malanushenko, Elena; Malanushenko, Viktor; Marriner, John; Miquel, Ramon; Montero-Dorta, Antonio D.; Nichol, Robert C.; Oravetz, Daniel J.; Pan, Kaike; Schneider, Donald P.; Simmons, Audrey E.; Smith, Mathew; Snedden, Stephanie A.

    2014-03-06

    We present the spectroscopy from 5254 galaxies that hosted supernovae (SNe) or other transient events in the Sloan Digital Sky Survey II (SDSS-II). Obtained during SDSS-I, SDSS-II, and the Baryon Oscillation Spectroscopic Survey (BOSS), this sample represents the largest systematic, unbiased, magnitude limited spectroscopic survey of supernova (SN) host galaxies. Using the host galaxy redshifts, we test the impact of photometric SN classification based on SDSS imaging data with and without using spectroscopic redshifts of the host galaxies. Following our suggested scheme, there are a total of 1166 photometrically classified SNe Ia when using a flat redshift prior and 1126 SNe Ia when the host spectroscopic redshift is assumed. For 1024 (87.8%) candidates classified as likely SNe Ia without redshift information, we find that the classification is unchanged when adding the host galaxy redshift. Using photometry from SDSS imaging data and the host galaxy spectra, we also report host galaxy properties for use in future nalysis of SN astrophysics. Finally, we investigate the differences in the interpretation of the light curve properties with and without knowledge of the redshift. When using the SALT2 light curve fitter, we find a 21% increase in the number of fits that converge when using the spectroscopic redshift. Without host galaxy redshifts, we find that SALT2 light curve fits are systematically biased towards lower photometric redshift estimates and redder colors in the limit of low signal-to-noise data. The general improvements in performance of the light curve fitter and the increased diversity of the host galaxy sample highlights the importance of host galaxy spectroscopy for current photometric SN surveys such as the Dark Energy Survey and future surveys such as the Large Synoptic Survey Telescope.

  18. Interplay between chaotic and regular motion in a time-dependent barred galaxy model

    Science.gov (United States)

    Manos, T.; Bountis, T.; Skokos, Ch

    2013-06-01

    We study the distinction and quantification of chaotic and regular motion in a time-dependent Hamiltonian barred galaxy model. Recently, a strong correlation was found between the strength of the bar and the presence of chaotic motion in this system, as models with relatively strong bars were shown to exhibit stronger chaotic behavior compared to those having a weaker bar component. Here, we attempt to further explore this connection by studying the interplay between chaotic and regular behavior of star orbits when the parameters of the model evolve in time. This happens for example when one introduces linear time dependence in the mass parameters of the model to mimic, in some general sense, the effect of self-consistent interactions of the actual N-body problem. We thus observe, in this simple time-dependent model also, that the increase of the bar’s mass leads to an increase of the system’s chaoticity. We propose a new way of using the generalized alignment index (GALI) method as a reliable criterion to estimate the relative fraction of chaotic versus regular orbits in such time-dependent potentials, which proves to be much more efficient than the computation of Lyapunov exponents. In particular, GALI is able to capture subtle changes in the nature of an orbit (or ensemble of orbits) even for relatively small time intervals, which makes it ideal for detecting dynamical transitions in time-dependent systems. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Lyapunov analysis: from dynamical systems theory to applications’.

  19. Comparison between 2D and 3D codes in dynamical simulations of gas flow in barred galaxies

    NARCIS (Netherlands)

    Perez, I.

    Context. One of the ways to determine the contribution of the dark halo to the gravitational potential of a galaxy is study non-circular (streaming) motions and the associated gas shocks in the bar region. These motions, determined by the potential in the inner parts, can break the disk-halo

  20. ON THE HOST GALAXY OF GRB 150101B AND THE ASSOCIATED ACTIVE GALACTIC NUCLEUS

    International Nuclear Information System (INIS)

    Xie, Chen; Fang, Taotao; Wang, Junfeng; Liu, Tong; Jiang, Xiaochuan

    2016-01-01

    We present a multi-wavelength analysis of the host galaxy of short-duration gamma-ray burst (GRB) 150101B. Follow-up optical and X-ray observations suggested that the host galaxy, 2MASX J12320498-1056010, likely harbors low-luminosity active galactic nuclei (AGNs). Our modeling of the spectral energy distribution has confirmed the nature of the AGN, making it the first reported GRB host that contains an AGN. We have also found the host galaxy is a massive elliptical galaxy with stellar population of ∼5.7 Gyr, one of the oldest among the short-duration GRB hosts. Our analysis suggests that the host galaxy can be classified as an X-ray bright, optically normal galaxy, and the central AGN is likely dominated by a radiatively inefficient accretion flow. Our work explores an interesting connection that may exist between GRB and AGN activities of the host galaxy, which can help in understanding the host environment of the GRB events and the roles of AGN feedback.

  1. Spatially-resolved dust properties of the GRB 980425 host galaxy

    DEFF Research Database (Denmark)

    Michałowski, Michał J.; Hunt, L. K.; Palazzi, E.

    2014-01-01

    Gamma-ray bursts (GRBs) have been proposed as a tool to study star formation in the Universe, so it is crucial to investigate whether their host galaxies and immediate environments are in any way special compared with other star-forming galaxies. Here we present spatially resolved maps of dust...... emission of the host galaxy of the closest known GRB 980425 at z=0.0085 using our new high-resolution observations from Herschel, APEX, ALMA and ATCA. We modeled the spectral energy distributions of the host and of the star-forming region displaying the Wolf-Rayet signatures in the spectrum (WR region......), located 800 pc away from the GRB position. The host is characterised by low dust content and high fraction of UV-visible star-formation, similar to other dwarf galaxies. Such galaxies are abundant in the local universe, so it is not surprising to find a GRB in one of them, assuming the correspondence...

  2. Type Ia Supernova Hubble Residuals and Host-Galaxy Properties

    Energy Technology Data Exchange (ETDEWEB)

    Nearby Supernova Factory; Kim, A. G.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Childress, M.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Feindt, U.; Fleury, M.; Gangler, E.; Greskovic, P.; Guy, J.; Kowalski, M.; Lombardo, S.; Nordin, J.; Nugent, P.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Saunders, C.; Scalzo, R.; Smadja, G.; Tao, C.; Thomas, R. C.; Weaver, B. A.

    2014-01-17

    Kim et al. (2013) [K13] introduced a new methodology for determining peak- brightness absolute magnitudes of type Ia supernovae from multi-band light curves. We examine the relation between their parameterization of light curves and Hubble residuals, based on photometry synthesized from the Nearby Supernova Factory spec- trophotometric time series, with global host-galaxy properties. The K13 Hubble residual step with host mass is 0.013 ? 0.031 mag for a supernova subsample with data coverage corresponding to the K13 training; at ? 1?, the step is not significant and lower than previous measurements. Relaxing the data coverage requirement the Hubble residual step with host mass is 0.045 ? 0.026 mag for the larger sample; a calculation using the modes of the distributions, less sensitive to outliers, yields a step of 0.019 mag. The analysis of this article uses K13 inferred luminosities, as distinguished from previous works that use magnitude corrections as a function of SALT2 color and stretch param- eters: Steps at> 2? significance are found in SALT2 Hubble residuals in samples split by the values of their K13 x(1) and x(2) light-curve parameters. x(1) affects the light- curve width and color around peak (similar to the∆m15 and stretch parameters), and x(2) affects colors, the near-UV light-curve width, and the light-curve decline 20 to 30 days after peak brightness. The novel light-curve analysis, increased parameter set, and magnitude corrections of K13 may be capturing features of SN Ia diversity arising from progenitor stellar evolution.

  3. Type Ia supernova Hubble residuals and host-galaxy properties

    Energy Technology Data Exchange (ETDEWEB)

    Kim, A. G.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Fleury, M.; Guy, J. [Laboratoire de Physique Nucléaire et des Hautes Énergies, Université Pierre et Marie Curie Paris 6, Université Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Buton, C.; Feindt, U.; Greskovic, P.; Kowalski, M. [Physikalisches Institut, Universität Bonn, Nußallee 12, D-53115 Bonn (Germany); Childress, M. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Chotard, N.; Copin, Y.; Gangler, E. [Université de Lyon, F-69622 Lyon (France); Université de Lyon 1, Villeurbanne (France); CNRS/IN2P3, Institut de Physique Nucléaire de Lyon (France); and others

    2014-03-20

    Kim et al. introduced a new methodology for determining peak-brightness absolute magnitudes of type Ia supernovae from multi-band light curves. We examine the relation between their parameterization of light curves and Hubble residuals, based on photometry synthesized from the Nearby Supernova Factory spectrophotometric time series, with global host-galaxy properties. The K13 Hubble residual step with host mass is 0.013 ± 0.031 mag for a supernova subsample with data coverage corresponding to the K13 training; at <<1σ, the step is not significant and lower than previous measurements. Relaxing the data coverage requirement of the Hubble residual step with the host mass is 0.045 ± 0.026 mag for the larger sample; a calculation using the modes of the distributions, less sensitive to outliers, yields a step of 0.019 mag. The analysis of this article uses K13 inferred luminosities, as distinguished from previous works that use magnitude corrections as a function of SALT2 color and stretch parameters: steps at >2σ significance are found in SALT2 Hubble residuals in samples split by the values of their K13 x(1) and x(2) light-curve parameters. x(1) affects the light-curve width and color around peak (similar to the Δm {sub 15} and stretch parameters), and x(2) affects colors, the near-UV light-curve width, and the light-curve decline 20-30 days after peak brightness. The novel light-curve analysis, increased parameter set, and magnitude corrections of K13 may be capturing features of SN Ia diversity arising from progenitor stellar evolution.

  4. X-Ray bright active galactic nuclei in massive galaxy clusters - II. The fraction of galaxies hosting active nuclei

    DEFF Research Database (Denmark)

    Ehlert, S.; von der Linden, A.; Allen, S. W.

    2013-01-01

    We present a measurement of the fraction of cluster galaxies hosting X-ray bright active galactic nuclei (AGN) as a function of clustercentric distance scaled in units of r500. Our analysis employs high-quality Chandra X-ray and Subaru optical imaging for 42 massive X-ray-selected galaxy cluster...... fields spanning the redshift range 0.2 galaxies from the calculation, we measure a cluster galaxy AGN fraction in the central...... regions of the clusters that is~3 times lower than the field value. This fraction increases with clustercentric distance before becoming consistent with the field at ~2.5r500. Our data exhibit similar radial trends to those observed for star formation and optically selected AGN in cluster member galaxies...

  5. Modeling The GRB Host Galaxy Mass Distribution: Are GRBs Unbiased Tracers of Star Formation?

    Energy Technology Data Exchange (ETDEWEB)

    Kocevski, Daniel; /KIPAC, Menlo Park; West, Andrew A.; /UC, Berkeley, Astron. Dept. /MIT, MKI; Modjaz, Maryam; /UC, Berkeley, Astron. Dept.

    2009-08-03

    We model the mass distribution of long gamma-ray burst (GRB) host galaxies given recent results suggesting that GRBs occur in low metallicity environments. By utilizing measurements of the redshift evolution of the mass-metallicity (M-Z) relationship for galaxies, along with a sharp host metallicity cut-off suggested by Modjaz and collaborators, we estimate an upper limit on the stellar mass of a galaxy that can efficiently produce a GRB as a function of redshift. By employing consistent abundance indicators, we find that sub-solar metallicity cut-offs effectively limit GRBs to low stellar mass spirals and dwarf galaxies at low redshift. At higher redshifts, as the average metallicity of galaxies in the Universe falls, the mass range of galaxies capable of hosting a GRB broadens, with an upper bound approaching the mass of even the largest spiral galaxies. We compare these predicted limits to the growing number of published GRB host masses and find that extremely low metallicity cut-offs of 0.1 to 0.5 Z{sub {circle_dot}} are effectively ruled out by a large number of intermediate mass galaxies at low redshift. A mass function that includes a smooth decrease in the efficiency of producing GRBs in galaxies of metallicity above 12+log(O/H){sub KK04} = 8.7 can, however, accommodate a majority of the measured host galaxy masses. We find that at z {approx} 1, the peak in the observed GRB host mass distribution is inconsistent with the expected peak in the mass of galaxies harboring most of the star formation. This suggests that GRBs are metallicity biased tracers of star formation at low and intermediate redshifts, although our model predicts that this bias should disappear at higher redshifts due to the evolving metallicity content of the universe.

  6. MODELING THE GRB HOST GALAXY MASS DISTRIBUTION: ARE GRBs UNBIASED TRACERS OF STAR FORMATION?

    International Nuclear Information System (INIS)

    Kocevski, Daniel; West, Andrew A.; Modjaz, Maryam

    2009-01-01

    We model the mass distribution of long gamma-ray burst (GRB) host galaxies given recent results suggesting that GRBs occur in low-metallicity environments. By utilizing measurements of the redshift evolution of the mass-metallicity relationship for galaxies, along with a sharp host metallicity cutoff suggested by Modjaz and collaborators, we estimate an upper limit on the stellar mass of a galaxy that can efficiently produce a GRB as a function of redshift. By employing consistent abundance indicators, we find that subsolar metallicity cutoffs effectively limit GRBs to low-stellar mass spirals and dwarf galaxies at low redshift. At higher redshifts, as the average metallicity of galaxies in the Universe falls, the mass range of galaxies capable of hosting a GRB broadens, with an upper bound approaching the mass of even the largest spiral galaxies. We compare these predicted limits to the growing number of published GRB host masses and find that extremely low-metallicity cutoffs of 0.1 to 0.5 Z sun are effectively ruled out by a large number of intermediate mass galaxies at low redshift. A mass function that includes a smooth decrease in the efficiency of producing GRBs in galaxies of metallicity above 12+log(O/H) KK04 = 8.7 can, however, accommodate a majority of the measured host galaxy masses. We find that at z ∼ 1, the peak in the observed GRB host mass distribution is inconsistent with the expected peak in the mass of galaxies harboring most of the star formation. This suggests that GRBs are metallicity-biased tracers of star formation at low and intermediate redshifts, although our model predicts that this bias should disappear at higher redshifts due to the evolving metallicity content of the universe.

  7. Molecular Gasdynamics of the Young Nuclear Starburst in the Barred Galaxy NGC 3504

    Science.gov (United States)

    Kenney, Jeffrey D. P.; Carlstrom, John E.; Young, Judith S.

    1993-12-01

    We present CO (J = 1 → 0) interferometry at 2".5 resolution and Hα CCD observations of the circumnuclear starburst region of the barred spiral galaxy NGC 3504. The CO emission is centrally peaked, extends over a region 16" (1.6 kpc) in diameter, and is relatively azimuthally symmetric. The CO radial distribution is well fitted by an exponential with a scale length of 2".3 (220 pc). This simple distribution is surprisingly unusual for the center of a galaxy. The velocity field is consistent with purely circular motions. Gas comprises ˜40% of the dynamical mass within a radius of 100 pc (1"), if the "standard" CO-H2 relationship is assumed. If isothermal and self-gravitating, the circumnuclear gas disk has a scale height of only 5-10 pc, and a spatially averaged proton density of 104 cm-3 at radii less than 300 pc. The rotation curve and the dust-lane morphology indicate the presence of an outer inner Lindblad resonance (OILR) at a radius of ˜5", and an inner inner Lindblad resonance (IILR) at a radius of ˜2". The starburst and most of the circumnuclear gas disk seem to be located between the OILR and the IILR. The maximum value of Ω-κ/2 is nearly twice as large as the bar pattern speed of the large-scale bar, and the OILR and the IILR are well separated, and these may be important dynamical differences between NGC 3504 and nonstarburst barred galaxies. The rate of high-mass star formation per unit gas mass, as traced by the ratio of Hα to CO emission, is uniformly high over the portion of the rotation curve which is nearly solid body, and drops by a factor of ˜4 where the rotation curve turns over and flattens out. Since the CO radial distribution is not ringlike despite the fact that gas is being consumed more rapidly in the center, we believe that the starburst in NGC 3504 is in an early phase of its evolution. The Toomre Q stability parameter is approximately constant at 0.9±0.2 throughout the circumnuclear molecular gas disk, so the simple

  8. The Effect of Host Galaxies on Type Ia Supernovae in the SDSS-II Supernova Survey

    Energy Technology Data Exchange (ETDEWEB)

    Lampeitl, Hubert; /Portsmouth U., ICG; Smith, Mathew; /Cape Town U. /Portsmouth U., ICG; Nichol, Robert C.; /Portsmouth U., ICG; Bassett, Bruce; /South African Astron. Observ. /Cape Town U.; Cinabro, David; /Wayne State U.; Dilday, Benjamin; /Rutgers U., Piscataway; Foley, Ryan J.; /Harvard-Smithsonian Ctr. Astrophys.; Frieman, Joshua A.; /Chicago U. /Fermilab; Garnavich, Peter M.; /Notre Dame U.; Goobar, Ariel; /Stockholm U., OKC; Im, Myungshin; /Seoul Natl. U. /Rutgers U., Piscataway

    2010-05-01

    We present an analysis of the host galaxy dependencies of Type Ia Supernovae (SNe Ia) from the full three year sample of the SDSS-II Supernova Survey. We re-discover, to high significance, the strong correlation between host galaxy type and the width of the observed SN light curve, i.e., fainter, quickly declining SNe Ia favor passive host galaxies, while brighter, slowly declining Ia's favor star-forming galaxies. We also find evidence (at between 2 to 3{sigma}) that SNe Ia are {approx_equal} 0.1 magnitudes brighter in passive host galaxies, than in star-forming hosts, after the SN Ia light curves have been standardized using the light curve shape and color variations: This difference in brightness is present in both the SALT2 and MCLS2k2 light curve fitting methodologies. We see evidence for differences in the SN Ia color relationship between passive and star-forming host galaxies, e.g., for the MLCS2k2 technique, we see that SNe Ia in passive hosts favor a dust law of R{sub V} {approx_equal} 1, while SNe Ia in star-forming hosts require R{sub V} {approx} 2. The significance of these trends depends on the range of SN colors considered. We demonstrate that these effects can be parameterized using the stellar mass of the host galaxy (with a confidence of > 4{sigma}) and including this extra parameter provides a better statistical fit to our data. Our results suggest that future cosmological analyses of SN Ia samples should include host galaxy information.

  9. Long-Duration Gamma-Ray Burst Host Galaxies in Emission and Absorption

    Science.gov (United States)

    Perley, Daniel A.; Niino, Yuu; Tanvir, Nial R.; Vergani, Susanna D.; Fynbo, Johan P. U.

    2016-12-01

    The galaxy population hosting long-duration GRBs provides a means to constrain the progenitor and an opportunity to use these violent explosions to characterize the nature of the high-redshift universe. Studies of GRB host galaxies in emission reveal a population of star-forming galaxies with great diversity, spanning a wide range of masses, metallicities, and redshifts. However, as a population GRB hosts are significantly less massive and poorer in metals than the hosts of other core-collapse transients, suggesting that GRB production is only efficient at metallicities significantly below Solar. GRBs may also prefer compact galaxies, and dense and/or central regions of galaxies, more than other types of core-collapse explosion. Meanwhile, studies of hosts in absorption against the luminous GRB optical afterglow provide a unique means of unveiling properties of the ISM in even the faintest and most distant galaxies; these observations are helping to constrain the chemical evolution of galaxies and the properties of interstellar dust out to very high redshifts. New ground- and space-based instrumentation, and the accumulation of larger and more carefully-selected samples, are continually enhancing our view of the GRB host population.

  10. Morphologies of Mid-IR Variability-Selected AGN Host Galaxies

    Science.gov (United States)

    Polimera, Mugdha; Sarajedini, Vicki; Ashby, Matthew L. N.; Willner, S. P.; Fazio, Giovanni G.

    2018-01-01

    We use multi-epoch 3.6 and 4.5 {μ m} data from the Spitzer Extended Deep Survey (SEDS) to probe the AGN population among galaxies to redshifts ˜3 via their mid-IR variability. About 1% of all galaxies in our survey contain varying nuclei, 80% of which are likely to be AGN. Twenty-three percent of mid-IR variables are also X-ray sources. The mid-IR variables have a slightly greater fraction of weakly disturbed morphologies compared to a control sample of normal galaxies. The increased fraction of weakly distorted hosts becomes more significant when we remove the X-ray emitting AGN, while the frequency of strongly disturbed hosts remains similar to the control galaxy sample. These results suggest that mid-IR variability identifies a unique population of obscured, Compton-thick AGN revealing elevated levels of weak distortion among their host galaxies.

  11. Correlations Between Central Massive Objects And Their Host Galaxies: From Bulgeless Spirals to Ellipticals

    OpenAIRE

    Li, Yuexing; Haiman, Zoltán; Mac Low, Mordecai-Mark

    2006-01-01

    Recent observations by Ferrarese et al. (2006) and Wehner et al. (2006) reveal that a majority of galaxies contain a central massive object (CMO), either a supermassive black hole (SMBH) or a compact stellar nucleus, regardless of the galaxy mass or morphological type, and that there is a tight relation between the masses of CMOs and those of the host galaxies. Several recent studies show that feedback from black holes can successfully explain the $\\msigma$ correlation in massive elliptical g...

  12. The host galaxy and optical light curve of the gamma-ray burst GRB 980703

    DEFF Research Database (Denmark)

    Holland, S.; Fynbo, J.P.U.; Hjorth, J.

    2001-01-01

    that is approximate to0.2 mag bluer than the outer regions of the galaxy. The galaxy has a star-formation rate of 8-13 M-circle dot yr(-1), assuming no extinction in the host. We find that the galaxy is best fit by a Sersic R-1/n profile with n approximate to 1.0 and a half-light radius of 0." 13 (= 0:72h(100...

  13. A Hubble Space Telescope imaging study of four FeLoBAL quasar host galaxies

    Science.gov (United States)

    Lawther, D.; Vestergaard, M.; Fan, X.

    2018-04-01

    We study the host galaxies of four Iron Low-Ionization Broad Absorption-line Quasars (FeLoBALs), using Hubble Space Telescope imaging data, investigating the possibility that they represent a transition between an obscured active galactic nucleus (AGN) and an ordinary optical quasar. In this scenario, the FeLoBALs represent the early stage of merger-triggered accretion, in which case their host galaxies are expected to show signs of an ongoing or recent merger. Using PSF subtraction techniques, we decompose the images into host galaxy and AGN components at rest-frame ultraviolet and optical wavelengths. The ultraviolet is sensitive to young stars, while the optical probes stellar mass. In the ultraviolet we image at the BAL absorption trough wavelengths so as to decrease the contrast between the quasar and host galaxy emission. We securely detect an extended source for two of the four FeLoBALs in the rest-frame optical; a third host galaxy is marginally detected. In the rest-frame UV we detect no host emission; this constrains the level of unobscured star formation. Thus, the host galaxies have observed properties that are consistent with those of non-BAL quasars with the same nuclear luminosity, i.e. quiescent or moderately star-forming elliptical galaxies. However, we cannot exclude starbursting hosts that have the stellar UV emission obscured by modest amounts of dust reddening. Thus, our findings also allow the merger-induced young quasar scenario. For three objects, we identify possible close companion galaxies that may be gravitationally interacting with the quasar hosts.

  14. The Host Galaxies of Type Ia Supernovae Discovered by the Palomar Transient Factory

    Science.gov (United States)

    Pan, Y.-C.; Sullivan, M.; McGuire, K.; Hook, I. M.; Nugent, P. E.; Howell, D. A.; Arcavi, I.; Botyanszki, J.; Cenko, Stephen Bradley; DeRose, J.

    2013-01-01

    We present spectroscopic observations of the host galaxies of 82 low-redshift type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF). We determine star-formation rates, gas-phase stellar metallicities, and stellar masses and ages of these objects. As expected, strong correlations between the SN Ia light-curve width (stretch) and the host age mass metallicity are found: fainter, faster-declining events tend to be hosted by older massive metal-rich galaxies. There is some evidence that redder SNe Ia explode in higher metallicity galaxies, but we found no relation between the SN colour and host galaxy extinction based on the Balmer decrement, suggesting that the colour variation of these SNe does not primarily arise from this source. SNe Ia in higher-mass metallicity galaxies also appear brighter after stretch colour corrections than their counterparts in lower mass hosts, and the stronger correlation is with gas-phase metallicity suggesting this may be the more important variable. We also compared the host stellar mass distribution to that in galaxy targeted SN surveys and the high-redshift untargeted Supernova Legacy Survey (SNLS). SNLS has many more low mass galaxies, while the targeted searches have fewer. This can be explained by an evolution in the galaxy stellar mass function, coupled with a SN delay-time distribution proportional to t1. Finally, we found no significant difference in the mass--metallicity relation of our SN Ia hosts compared to field galaxies, suggesting any metallicity effect on the SN Ia rate is small.

  15. The unique structural parameters of the underlying host galaxies in blue compact dwarfs

    International Nuclear Information System (INIS)

    Janowiecki, Steven; Salzer, John J.

    2014-01-01

    The nature of possible evolutionary pathways between various types of dwarf galaxies is still not fully understood. Blue compact dwarf galaxies (BCDs) provide a unique window into dwarf galaxy formation and evolution and are often thought of as an evolutionary stage between different classes of dwarf galaxies. In this study we use deep optical and near-infrared observations of the underlying hosts of BCDs in order to study the structural differences between different types of dwarf galaxies. When compared with dwarf irregular galaxies of similar luminosities, we find that the underlying hosts of BCDs have significantly more concentrated light distributions, with smaller scale lengths and brighter central surface brightnesses. We demonstrate here that the underlying hosts of BCDs are distinct from the broad continuum of typical dwarf irregular galaxies, and that it is unlikely that most dwarf irregular galaxies can transform into a BCD or vice versa. Furthermore, we find that the starburst in a BCD only brightens it on average by ∼0.8 mag (factor of two), in agreement with other studies. It appears that a BCD is a long-lived and distinct type of dwarf galaxy that exhibits an exceptionally concentrated matter distribution. We suggest that it is this compact mass distribution that enables the strong star formation events that characterize this class of dwarf galaxy, that the compactness of the underlying host can be used as a distinguishing parameter between BCDs and other dwarf galaxies, and that it can also be used to identify BCDs which are not currently experiencing an intense starburst event.

  16. A Statistical Study of H I Gas in Nearby Narrow-Line AGN-Hosting Galaxies

    OpenAIRE

    Zhu, Yi-Nan; Wu, Hong

    2014-01-01

    As a quenching mechanism, AGN feedback could suppress on-going star formation in their host galaxies. On the basis of a sample of galaxies selected from ALFALFA HI survey, the dependence of their HI mass M[HI], stellar mass M[*] & HI-to-stellar mass ratio M[HI]/M[*] on various tracers of AGN activity are presented and analyzed in this paper. Almost all the AGN-hostings in this sample are gas-rich galaxies, and there is no any evidence to be shown to indicate that the AGN activity could increa...

  17. A molecular gas-rich GRB host galaxy at the peak of cosmic star formation

    Science.gov (United States)

    Arabsalmani, M.; Le Floc'h, E.; Dannerbauer, H.; Feruglio, C.; Daddi, E.; Ciesla, L.; Charmandaris, V.; Japelj, J.; Vergani, S. D.; Duc, P.-A.; Basa, S.; Bournaud, F.; Elbaz, D.

    2018-05-01

    We report the detection of the CO(3-2) emission line from the host galaxy of gamma-ray burst (GRB) 080207 at z = 2.086. This is the first detection of molecular gas in emission from a GRB host galaxy beyond redshift 1. We find this galaxy to be rich in molecular gas with a mass of 1.1 × 10^{11} M_{{\\odot }} assuming αCO = 4.36 M_{{\\odot }} (K km s^{-1} pc^2)^{-1}. The molecular gas mass fraction of the galaxy is ˜0.5, typical of star-forming galaxies (SFGs) with similar stellar masses and redshifts. With an SFR_{FIR} of 260 M_{{\\odot }} yr^{-1}, we measure a molecular gas depletion time-scale of 0.43 Gyr, near the peak of the depletion time-scale distribution of SFGs at similar redshifts. Our findings are therefore in contradiction with the proposed molecular gas deficiency in GRB host galaxies. We argue that the reported molecular gas deficiency for GRB hosts could be the artefact of improper comparisons or neglecting the effect of the typical low metallicities of GRB hosts on the CO-to-molecular-gas conversion factor. We also compare the kinematics of the CO(3-2) emission line to that of the H α emission line from the host galaxy. We find the H α emission to have contributions from two separate components, a narrow and a broad one. The narrow component matches the CO emission well in velocity space. The broad component, with a full width at half-maximum of ˜1100 km s^{-1}, is separated by +390 km s^{-1} in velocity space from the narrow component. We speculate this broad component to be associated with a powerful outflow in the host galaxy or in an interacting system.

  18. HOST GALAXY PROPERTIES OF THE SWIFT BAT ULTRA HARD X-RAY SELECTED ACTIVE GALACTIC NUCLEUS

    International Nuclear Information System (INIS)

    Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain; Winter, Lisa M.; Baumgartner, Wayne; Tueller, Jack; Gehrels, Neil; Valencic, Lynne

    2011-01-01

    We have assembled the largest sample of ultra hard X-ray selected (14-195 keV) active galactic nucleus (AGN) with host galaxy optical data to date, with 185 nearby (z * >10.5) have a 5-10 times higher rate of spiral morphologies than in SDSS AGNs or inactive galaxies. We also see enhanced far-infrared emission in BAT AGN suggestive of higher levels of star formation compared to the comparison samples. BAT AGNs are preferentially found in the most massive host galaxies with high concentration indexes indicative of large bulge-to-disk ratios and large supermassive black holes. The narrow-line (NL) BAT AGNs have similar intrinsic luminosities as the SDSS NL Seyferts based on measurements of [O III] λ5007. There is also a correlation between the stellar mass and X-ray emission. The BAT AGNs in mergers have bluer colors and greater ultra hard X-ray emission compared to the BAT sample as a whole. In agreement with the unified model of AGNs, and the relatively unbiased nature of the BAT sources, the host galaxy colors and morphologies are independent of measures of obscuration such as X-ray column density or Seyfert type. The high fraction of massive spiral galaxies and galaxy mergers in BAT AGNs suggest that host galaxy morphology is related to the activation and fueling of local AGN.

  19. LUMINOSITY FUNCTIONS OF TYPE Ia SUPERNOVAE AND THEIR HOST GALAXIES FROM THE SLOAN DIGITAL SKY SURVEY

    International Nuclear Information System (INIS)

    Yasuda, Naoki; Fukugita, Masataka

    2010-01-01

    The sample of 137 low-redshift type Ia supernovae (SNe Ia) with 0.05 ≤ z ≤ 0.3 obtained from the Sloan Digital Sky Survey (SDSS)-II supernova survey for the southern equatorial stripe of 300 deg 2 is used to derive the luminosity functions (LFs) of SNe Ia and of their host galaxies in the g, r, i passbands. We show that the LF of SNe Ia host galaxies matches well with that of galaxies in the general field, suggesting that the occurrence of SNe Ia does not favor a particular type of galaxy but is predominantly proportional to the luminosity of galaxies. The evidence is weak that the SNe rate varies with the color of host galaxies. The only evidence that points to possible correlation between the SN rate and star formation activity is that the SN rate in late-type galaxies is higher than that in early-type galaxies by 31% ± 35%. In our low-redshift sample, the component of type Ia SN rate that is proportional to star formation activity is not evident in the integrated SN rate, while our observation is compatible with the current two-component models. The sample contains eight SNe Ia whose host galaxies were not identified, but it is shown that their occurrence is consistent with them occurring in low-luminous galaxies beyond the survey. The LF of SNe Ia is approximately Gaussian with the full width at half-maximum being a factor of σ = 0.24 mag or 1.67 in luminosity. The Gaussian distribution becomes tighter if the ratio of extinction to reddening, R V , is lower than the characteristic value for the Milky Way and if luminosity is corrected for the light-curve shape. The average color excess is ∼0.07 mag, which is significantly smaller than reddening expected for field galaxies. This color excess does not vary with the distance of the SNe from the center of the host galaxy to 15 kpc. This suggests that the major part of the color excess appears to be either intrinsic or reddening that arises in the immediate environment of SNe, rather than interstellar

  20. Estimatining biases in the stellar dynamical black hole mass measurements in barred galaxies and prospects for measuring SMBH masses with JWST

    Science.gov (United States)

    Valluri, Monica; Vasiliev, Eugene; Bentz, Misty; Shen, Juntai

    2018-04-01

    Although 60% of disk galaxies are barred, stellar dynamical measurements of the masses of supermassive black holes (SMBH) in barred galaxies have always been obtained under the assumption that the bulges are axisymmetric. We use N-body simulations with self-consistently grown SMBHs in barred and unbarred galaxies to create a suite of mock Integral Field Spectrographic (IFS) datasets for galaxies with various observed orientations. We then apply an axisymmetric orbit superposition code to these mock IFS datasets to assess the reliability with which SMBH masses can be recovered. We also assess which disk and bar orientations give rise to biases. We use these simulations to assess whether or not existing SMBH measurements in barred galaxies are likely to be biased. We also present a brief preview of our JWST Early Release Science proposal to study the nuclear dynamics of nearby Seyfert I galaxy NGC 4151 with the NIRSpec Integral Field Spectrograph and describe how simulations of disk galaxies will used to create mock NIRSpec data to prepare for the real data.

  1. Do Typical Galaxies in Adolescence Already Host Growing Black Holes?

    Science.gov (United States)

    Trump, Jonathan

    2012-10-01

    This archival grism proposal achieves a 100-fold gain in high-quality {5+sigma} information for discovering which properties of adolescent {0.7galaxies of typical mass and SFR are linked to AGN activity. We propose to analyze 147 WFC3 G141 and 111 ACS 800L pointings of 2-orbit grism data in the CANDELS fields, for a sample of 3000 galaxies reaching SFR 5 Msun/yr and stellar masses of log{M*/Msun} 9 at z 1.5. We will leverage spatially-resolved line ratios to uniquely distinguish a nuclear AGN from extended low-metallicity or shocked gas. Compared to our 30-galaxy published sample that hints at AGNs in low-mass z 2 galaxies {Trump et al. 2011}, this 3000 galaxy sample enables a 100-fold gain in divisions by galaxy morphology, SFR, and stellar mass to discover which galaxy properties correlate most with rapid SMBH growth. We will stack the deep {0.8-4 Ms} Chandra data available in these fields as an independent check of the grism AGN/SF diagnostics. The unique ancillary data in these fields also include ACS+WFC3 imaging for morphologies, deep multiwavelength data for well-sampled SEDs and stellar masses, and previous optical {and future near-IR} spectroscopy to supplement the G141 coverage. Based on discussions with the GOODS-N and 3D-HST teams, our proposed AGN science does not overlap with their proposed or funded science goals. As a value-added product for the community we will release, via the public Rainbow-CANDELS database server, an atlas of spatial maps of emission lines and line ratios {and associated errors} for the entire sample of 3000 galaxies.

  2. The MUSE QSO Blind Survey: A Census of Absorber Host Galaxies

    Science.gov (United States)

    Straka, Lorrie A.; MUSE GTO Consortium

    2017-03-01

    Understanding the distribution of gas in galaxies and its interaction with the IGM is crucial to complete the picture of galaxy evolution. At all redshifts, absorption features seen in QSO spectra serve as a unique probe of the gaseous content of foreground galaxies and the IGM, extending out to 200 kpc. Studies show that star formation history is intimately related to the co-evolution of galaxies and the IGM. In order to study the environments traced by absorption systems and the role of inflows and outflows, it is critical to measure the emission properties of host galaxies and their halos. We overcome the challenge of detecting absorption host galaxies with the MUSE integral field spectrograph on VLT. MUSE's large field of view and sensitivity to emission lines has allowed a never-before seen match between the number density of absorbers along QSO sightlines and the number density of emission line galaxies within 200 kpc of the QSO. These galaxies represent a sample for which previously elusive connections can be made between mass, metallicity, SFR, and absorption.

  3. A statistical study of H i gas in nearby narrow-line AGN-hosting galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yi-Nan; Wu, Hong, E-mail: zyn@bao.ac.cn, E-mail: hwu@bao.ac.cn [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2015-01-01

    As a quenching mechanism, active galactic nucleus (AGN) feedback could suppress on going star formation in host galaxies. On the basis of a sample of galaxies selected from the Arecibo Legacy Fast ALFA (ALFALFA) H i survey, the dependence of the H i mass (M{sub H} {sub i}), stellar mass (M{sub *}), and H i-to-stellar mass ratio (M{sub H} {sub i}/M{sub *}) on various tracers of AGN activity are presented and analyzed in this paper. Almost all the AGN hostings in this sample are gas-rich galaxies, and there is not any evidence to indicate that the AGN activity could increase or decrease either M{sub H} {sub i} or M{sub H} {sub i}/M{sub *}. The position of the cold neutral gas cannot be fixed accurately based only on available H i data, due to the large beam size of ALFALFA survey. In addition, even though AGN hostings are more easily detected by an H i survey compared with absorption line galaxies, these two types of galaxies show similar star formation history. If an AGN hosting would ultimately evolve into an old red galaxy with low cold gas, then when and how the gas has been exhausted must be solved by future hypotheses and observations.

  4. A statistical study of H i gas in nearby narrow-line AGN-hosting galaxies

    International Nuclear Information System (INIS)

    Zhu, Yi-Nan; Wu, Hong

    2015-01-01

    As a quenching mechanism, active galactic nucleus (AGN) feedback could suppress on going star formation in host galaxies. On the basis of a sample of galaxies selected from the Arecibo Legacy Fast ALFA (ALFALFA) H i survey, the dependence of the H i mass (M H i ), stellar mass (M * ), and H i-to-stellar mass ratio (M H i /M * ) on various tracers of AGN activity are presented and analyzed in this paper. Almost all the AGN hostings in this sample are gas-rich galaxies, and there is not any evidence to indicate that the AGN activity could increase or decrease either M H i or M H i /M * . The position of the cold neutral gas cannot be fixed accurately based only on available H i data, due to the large beam size of ALFALFA survey. In addition, even though AGN hostings are more easily detected by an H i survey compared with absorption line galaxies, these two types of galaxies show similar star formation history. If an AGN hosting would ultimately evolve into an old red galaxy with low cold gas, then when and how the gas has been exhausted must be solved by future hypotheses and observations.

  5. A Statistical Study of H I Gas in Nearby Narrow-Line AGN-Hosting Galaxies

    Science.gov (United States)

    Zhu, Yi-Nan; Wu, Hong

    2015-01-01

    As a quenching mechanism, active galactic nucleus (AGN) feedback could suppress on going star formation in host galaxies. On the basis of a sample of galaxies selected from the Arecibo Legacy Fast ALFA (ALFALFA) H i survey, the dependence of the H i mass (MH i), stellar mass (M*), and H i-to-stellar mass ratio (MH i/M*) on various tracers of AGN activity are presented and analyzed in this paper. Almost all the AGN hostings in this sample are gas-rich galaxies, and there is not any evidence to indicate that the AGN activity could increase or decrease either MH i or MH i/M*. The position of the cold neutral gas cannot be fixed accurately based only on available H i data, due to the large beam size of ALFALFA survey. In addition, even though AGN hostings are more easily detected by an H i survey compared with absorption line galaxies, these two types of galaxies show similar star formation history. If an AGN hosting would ultimately evolve into an old red galaxy with low cold gas, then when and how the gas has been exhausted must be solved by future hypotheses and observations.

  6. THE HOST GALAXIES OF GAMMA-RAY BURSTS. I. INTERSTELLAR MEDIUM PROPERTIES OF TEN NEARBY LONG-DURATION GAMMA-RAY BURST HOSTS

    International Nuclear Information System (INIS)

    Levesque, Emily M.; Kewley, Lisa J.; Berger, Edo; Bagley, Megan M.

    2010-01-01

    We present the first observations from a large-scale survey of nearby (z < 1) long-duration gamma-ray burst (LGRB) host galaxies, which consist of eight rest-frame optical spectra obtained at Keck and Magellan. Along with two host galaxy observations from the literature, we use optical emission-line diagnostics to determine metallicities, ionization parameters, young stellar population ages, and star formation rates. We compare the LGRB host environments to a variety of local and intermediate-redshift galaxy populations, as well as the newest grid of stellar population synthesis and photoionization models generated with the Starburst99/Mappings codes. With these comparisons, we investigate whether the GRB host galaxies are consistent with the properties of the general galaxy population, and therefore whether they may be used as reliable tracers of star formation. Despite the limitations inherent in our small sample, we find strong evidence that LGRB host galaxies generally have low-metallicity interstellar medium (ISM) environments out to z ∼ 1. The ISM properties of our GRB hosts, including metallicity and ionization parameter, are significantly different from the general galaxy population and host galaxies of nearby broad-lined Type Ic supernovae. However, these properties show better agreement with a sample of nearby metal-poor galaxies.

  7. The optical afterglow and host galaxy of GRB 000926

    DEFF Research Database (Denmark)

    Fynbo, J.U.; Gorosabel, J.; Dall, T.H.

    2002-01-01

    In this paper we illustrate with the case of GRB 000926 how Gamma Ray Bursts (GRBs) can be used as cosmological lighthouses to identify and study star forming galaxies at high redshifts. The optical afterglow of the burst was located with optical imaging at the Nordic Optical Telescope 20.7 hours...

  8. PSFGAN: a generative adversarial network system for separating quasar point sources and host galaxy light

    Science.gov (United States)

    Stark, Dominic; Launet, Barthelemy; Schawinski, Kevin; Zhang, Ce; Koss, Michael; Turp, M. Dennis; Sartori, Lia F.; Zhang, Hantian; Chen, Yiru; Weigel, Anna K.

    2018-03-01

    The study of unobscured active galactic nuclei (AGN) and quasars depends on the reliable decomposition of the light from the AGN point source and the extended host galaxy light. The problem is typically approached using parametric fitting routines using separate models for the host galaxy and the point spread function (PSF). We present a new approach using a Generative Adversarial Network (GAN) trained on galaxy images. We test the method using Sloan Digital Sky Survey (SDSS) r-band images with artificial AGN point sources added which are then removed using the GAN and with parametric methods using GALFIT. When the AGN point source PS is more than twice as bright as the host galaxy, we find that our method, PSFGAN, can recover PS and host galaxy magnitudes with smaller systematic error and a lower average scatter (49%). PSFGAN is more tolerant to poor knowledge of the PSF than parametric methods. Our tests show that PSFGAN is robust against a broadening in the PSF width of ±50% if it is trained on multiple PSF's. We demonstrate that while a matched training set does improve performance, we can still subtract point sources using a PSFGAN trained on non-astronomical images. While initial training is computationally expensive, evaluating PSFGAN on data is more than 40 times faster than GALFIT fitting two components. Finally, PSFGAN it is more robust and easy to use than parametric methods as it requires no input parameters.

  9. The Swift Gamma-Ray Burst Host Galaxy Legacy Survey. I. Sample Selection and Redshift Distribution

    Science.gov (United States)

    Perley, D. A.; Kruhler, T.; Schulze, S.; Postigo, A. De Ugarte; Hjorth, J.; Berger, E.; Cenko, S. B.; Chary, R.; Cucchiara, A.; Ellis, R.; hide

    2016-01-01

    We introduce the Swift Gamma-Ray Burst Host Galaxy Legacy Survey (SHOALS), a multi-observatory high redshift galaxy survey targeting the largest unbiased sample of long-duration gamma-ray burst (GRB) hosts yet assembled (119 in total). We describe the motivations of the survey and the development of our selection criteria, including an assessment of the impact of various observability metrics on the success rate of afterglow-based redshift measurement. We briefly outline our host galaxy observational program, consisting of deep Spitzer/IRAC imaging of every field supplemented by similarly deep, multicolor optical/near-IR photometry, plus spectroscopy of events without preexisting redshifts. Our optimized selection cuts combined with host galaxy follow-up have so far enabled redshift measurements for 110 targets (92%) and placed upper limits on all but one of the remainder. About 20% of GRBs in the sample are heavily dust obscured, and at most 2% originate from z > 5.5. Using this sample, we estimate the redshift-dependent GRB rate density, showing it to peak at z approx. 2.5 and fall by at least an order of magnitude toward low (z = 0) redshift, while declining more gradually toward high (z approx. 7) redshift. This behavior is consistent with a progenitor whose formation efficiency varies modestly over cosmic history. Our survey will permit the most detailed examination to date of the connection between the GRB host population and general star-forming galaxies, directly measure evolution in the host population over cosmic time and discern its causes, and provide new constraints on the fraction of cosmic star formation occurring in undetectable galaxies at all redshifts.

  10. Blending bias impacts the host halo masses derived from a cross-correlation analysis of bright submillimetre galaxies

    NARCIS (Netherlands)

    Cowley, William I.; Lacey, Cedric G.; Baugh, Carlton M.; Cole, Shaun; Wilkinson, Aaron

    2017-01-01

    Placing bright submillimetre galaxies (SMGs) within the broader context of galaxy formation and evolution requires accurate measurements of their clustering, which can constrain the masses of their host dark matter haloes. Recent work has shown that the clustering measurements of these galaxies may

  11. Possible Correlations between the Emission Properties of SGRBs and Their Offsets from the Host Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuai; Jin, Zhi-Ping; Li, Xiang; Fan, Yi-Zhong; Wei, Da-Ming [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, 210008 (China); Zhang, Fu-Wen, E-mail: jin@pmo.ac.cn, E-mail: yzfan@pmo.ac.cn, E-mail: dmwei@pmo.ac.cn [College of Science, Guilin University of Technology, Guilin 541004 (China)

    2017-07-20

    Short gamma-ray bursts (SGRBs) are widely believed to be from mergers of binary compact objects involving at least one neutron star and hence have a broad range of spatial offsets from their host galaxies. In this work, we search for possible correlations between the emission properties of 18 SGRBs and their offsets from the host galaxies. The SGRBs with and without extended emission do not show significant differences between their offset distributions, in agreement with some previous works. There are, however, possible correlations between the optical and X-ray afterglow emission and the offsets. The underlying physical origins are examined.

  12. Nuclear Star Clusters and the Stellar Spheroids of their Host Galaxies

    OpenAIRE

    Leigh, Nathan; Böker, Torsten; Knigge, Christian

    2012-01-01

    (Abridged) We combine published photometry for the nuclear star clusters (NSCs) and stellar spheroids of 51 low-mass, early-type galaxies in the Virgo cluster with empirical mass-to-light ratios, in order to complement previous studies that explore the dependence of NSC masses (M_{NSC}) on various properties of their host galaxies. We confirm a roughly linear relationship between M_{NSC} and luminous host spheroid mass (M_{Sph}), albeit with considerable scatter (0.57 dex). We estimate veloci...

  13. The MUSE view of the host galaxy of GRB 100316D

    Science.gov (United States)

    Izzo, L.; Thöne, C. C.; Schulze, S.; Mehner, A.; Flores, H.; Cano, Z.; de Ugarte Postigo, A.; Kann, D. A.; Amorín, R.; Anderson, J. P.; Bauer, F. E.; Bensch, K.; Christensen, L.; Covino, S.; Della Valle, M.; Fynbo, J. P. U.; Jakobsson, P.; Klose, S.; Kuncarayakti, H.; Leloudas, G.; Milvang-Jensen, B.; Møller, P.; Puech, M.; Rossi, A.; Sánchez-Ramírez, R.; Vergani, S. D.

    2017-12-01

    The low distance, z = 0.0591, of GRB 100316D and its association with SN 2010bh represent two important motivations for studying this host galaxy and the GRB's immediate environment with the integral field spectrographs like Very Large Telescope/Multi-Unit Spectroscopic Explorer. Its large field of view allows us to create 2D maps of gas metallicity, ionization level and the star formation rate (SFR) distribution maps, as well as to investigate the presence of possible host companions. The host is a late-type dwarf irregular galaxy with multiple star-forming regions and an extended central region with signatures of on-going shock interactions. The gamma-ray burst (GRB) site is characterized by the lowest metallicity, the highest SFR and the youngest (∼20-30 Myr) stellar population in the galaxy, which suggest a GRB progenitor stellar population with masses up to 20-40 M⊙. We note that the GRB site has an offset of ∼660 pc from the most luminous SF region in the host. The observed SF activity in this galaxy may have been triggered by a relatively recent gravitational encounter between the host and a small undetected (LH α ≤ 1036 erg s-1) companion.

  14. Spectroscopic Properties of Star-Forming Host Galaxies and Type Ia Supernova Hubble Residuals in a Nearly Unbiased Sample

    Energy Technology Data Exchange (ETDEWEB)

    D' Andrea, Chris B. [Univ. of Pennsylvania, Philadelphia, PA (United States); et al.

    2011-12-20

    We examine the correlation between supernova host galaxy properties and their residuals on the Hubble diagram. We use supernovae discovered during the Sloan Digital Sky Survey II - Supernova Survey, and focus on objects at a redshift of z < 0.15, where the selection effects of the survey are known to yield a complete Type Ia supernova sample. To minimize the bias in our analysis with respect to measured host-galaxy properties, spectra were obtained for nearly all hosts, spanning a range in magnitude of -23 < M_r < -17. In contrast to previous works that use photometric estimates of host mass as a proxy for global metallicity, we analyze host-galaxy spectra to obtain gas-phase metallicities and star-formation rates from host galaxies with active star formation. From a final sample of ~ 40 emission-line galaxies, we find that light-curve corrected Type Ia supernovae are ~ 0.1 magnitudes brighter in high-metallicity hosts than in low-metallicity hosts. We also find a significant (> 3{\\sigma}) correlation between the Hubble residuals of Type Ia supernovae and the specific star-formation rate of the host galaxy. We comment on the importance of supernova/host-galaxy correlations as a source of systematic bias in future deep supernova surveys.

  15. The extraordinarily bright optical afterglow of GRB 991208 and its host galaxy

    DEFF Research Database (Denmark)

    Castro-Tirado, A.J.; Sokolov, V.V.; Gorosabel, J.

    2001-01-01

    that GRB 991208 is at 3.7 Gpc (for H-0 = 60 km s(-1) Mpc(-1), Omega (0) = 1 and Lambda (0) = 0), implying an isotropic energy release of 1.15 10(53) erg which may. be relaxed by beaming by a factor >10(2). Precise astrometry indicates that the GRB coincides within 0.2" with the host galaxy, thus supporting...... a massive star origin. The absolute magnitude of the galaxy is M-B = -18.2, well below the knee of the galaxy luminosity function and we derive a star-forming rate of (11.5 +/- 7.1) M-circle dot yr(-1), which is much larger than the present-day rate in our Galaxy. The quasi simultaneous broad...

  16. The host galaxy of the gravitational wave recoiling black hole candidate 3C186

    Science.gov (United States)

    Chiaberge, Marco

    2017-08-01

    We discovered a gravitational wave (GW) recoiling black hole (BH) candidate in our HST WFC3 snapshot images of the radio-loud QSO 3C186. These events are expected to happen as a result of BH-BH mergers. This extremely energetic phenomenon leads to the production of an intense field of GWs, which in most cases are emitted anisotropically. As a result, the merged black hole may receive a kick and be displaced from the center of the host galaxy with velocities that can be as high as 4000 km/s. Depending on the relative orientation of the kick with respect to the line-of-sight, if the BH is active we expect to observe an offset QSO. Furthermore, the broad lines may be offset with respect to the narrow lines, which are emitted in the frame of the host. 3C186 shows all of the predicted observational features of a such an event. Spectra show offsets between narrow and broad emission lines of 2100km/s, and our HST image clearly shows that the QSO is offset by 1.3 with respect to the isophotal center of the host galaxy. Scenarios alternative to the GW kick as the origin for the observed features are unlikely, but still viable. Only HST allows us to obtain spatially resolved information, high sensitivity and stable PSF to better investigate the host galaxy properties. We will use ACS and WFC3 to obtain deep images and study the morphology of the host galaxy. We will unambiguously establish whether the host galaxy of 3C186 underwent a major merger and we will be able to set accurate constraints on the age of the merger. The proposed observations will have a tremendous impact on our knowledge of supermassive BH mergers and the associated emission of gravitational waves.

  17. Host galaxy properties of mergers of stellar binary black holes and their implications for advanced LIGO gravitational wave sources

    Science.gov (United States)

    Cao, Liang; Lu, Youjun; Zhao, Yuetong

    2018-03-01

    Understanding the host galaxy properties of stellar binary black hole (SBBH) mergers is important for revealing the origin of the SBBH gravitational wave sources detected by advanced LIGO and helpful for identifying their electromagnetic counterparts. Here, we present a comprehensive analysis of the host galaxy properties of SBBHs by implementing semi-analytical recipes for SBBH formation and merger into cosmological galaxy formation model. If the time delay between SBBH formation and merger ranges from ≲ Gyr to the Hubble time, SBBH mergers at redshift z ≲ 0.3 occur preferentially in big galaxies with stellar mass M* ≳ 2 × 1010 M⊙ and metallicities Z peaking at ˜0.6 Z⊙. However, the host galaxy stellar mass distribution of heavy SBBH mergers (M•• ≳ 50 M⊙) is bimodal with one peak at ˜109 M⊙ and the other peak at ˜2 × 1010 M⊙. The contribution fraction from host galaxies with Z ≲ 0.2 Z⊙ to heavy mergers is much larger than that to less heavy mergers. If SBBHs were formed in the early Universe (e.g. z > 6), their mergers detected at z ≲ 0.3 occur preferentially in even more massive galaxies with M* > 3 × 1010 M⊙ and in galaxies with metallicities mostly ≳ 0.2 Z⊙ and peaking at Z ˜ 0.6 Z⊙, due to later cosmic assembly and enrichment of their host galaxies. SBBH mergers at z ≲ 0.3 mainly occur in spiral galaxies, but the fraction of SBBH mergers that occur in elliptical galaxies can be significant if those SBBHs were formed in the early Universe; and about two-thirds of those mergers occur in the central galaxies of dark matter haloes. We also present results on the host galaxy properties of SBBH mergers at higher redshift.

  18. Hubble Space Telescope NICMOS observations of the host galaxies of powerful radio sources : Does size matter?

    NARCIS (Netherlands)

    de Vries, WH; O'Dea, CP; Barthel, PD; Fanti, C; Fanti, R; Lehnert, MD

    2000-01-01

    We present near-infrared J- and K-band imaging of a sample of powerful radio source host galaxies with the Hubble Space Telescope NICMOS2 camera. These sources have been selected on their double-lobed radio structure and include a wide range of projected radio source sizes. The largest projected

  19. The metallicity and dust content of a redshift 5 gamma-ray burst host galaxy

    Energy Technology Data Exchange (ETDEWEB)

    Sparre, M.; Krühler, T.; Fynbo, J. P. U.; Watson, D. J.; De Ugarte Postigo, A.; Hjorth, J.; Malesani, D. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen (Denmark); Hartoog, O. E.; Kaper, L. [Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam (Netherlands); Wiersema, K. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); D' Elia, V. [INAF/Rome Astronomical Observatory, via Frascati 33, I-00040 Monteporzio Catone (Roma) (Italy); Zafar, T. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Afonso, P. M. J. [Physics and Astronomy Department, American River College, 4700 College Oak Drive, Sacramento, CA 95841 (United States); Covino, S. [INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy); Flores, H. [Laboratoire GEPI, Observatoire de Paris, CNRS-UMR8111, Universite Paris Diderot 5 place Jules Janssen, F-92195 Meudon (France); Goldoni, P. [APC, Astroparticule et Cosmologie, Universite Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10, Rue Alice Domon et Léonie Duquet, F-75205 Paris, Cedex 13 (France); Greiner, J. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, D-85748 Garching (Germany); Jakobsson, P. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, IS-107 Reykjavik (Iceland); Klose, S. [Thüringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg (Germany); Levan, A. J., E-mail: sparre@dark-cosmology.dk [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); and others

    2014-04-20

    Observations of the afterglows of long gamma-ray bursts (GRBs) allow the study of star-forming galaxies across most of cosmic history. Here we present observations of GRB 111008A, from which we can measure metallicity, chemical abundance patterns, dust-to-metals ratio (DTM), and extinction of the GRB host galaxy at z = 5.0. The host absorption system is a damped Lyα absorber with a very large neutral hydrogen column density of log N(H I)/cm{sup −2}=22.30±0.06 and a metallicity of [S/H] = –1.70 ± 0.10. It is the highest-redshift GRB with such a precise metallicity measurement. The presence of fine-structure lines confirms the z = 5.0 system as the GRB host galaxy and makes this the highest redshift where Fe II fine-structure lines have been detected. The afterglow is mildly reddened with A{sub V} = 0.11 ± 0.04 mag, and the host galaxy has a DTM that is consistent with being equal to or lower than typical values in the Local Group.

  20. Star formation in the hosts of GHz peaked spectrum and compact steep spectrum radio galaxies

    NARCIS (Netherlands)

    Labiano, A.; O'Dea, C. P.; Barthel, P. D.; Vries, W. H. de; Baum, S. A.

    2007-01-01

    Abstract: AIMS: Search for star formation regions in the hosts of potentially young radio galaxies (Gigahertz Peaked Spectrum and Compact Steep Spectrum sources). METHODS: Near-UV imaging with the Hubble Space Telescope Advanced Camera for Surveys.} RESULTS: We find near-UV light which could be the

  1. Nearby supernova host galaxies from the CALIFA survey. II. Supernova environmental metallicity

    NARCIS (Netherlands)

    Galbany, L.; Stanishev, V.; Mourão, A. M.; Rodrigues, M.; Flores, H.; Walcher, C. J.; Sánchez, S. F.; García-Benito, R.; Mast, D.; Badenes, C.; González Delgado, R. M.; Kehrig, C.; Lyubenova, M.; Marino, R. A.; Mollá, M.; Meidt, S.; Pérez, E.; van de Ven, G.; Vílchez, J. M.

    2016-01-01

    The metallicity of a supernova progenitor, together with its mass, is one of the main parameters that can rule the progenitor's fate. We present the second study of nearby supernova (SN) host galaxies (0.005 ⊙) > 10 dex) by targeted searches. We neither found evidence that the metallicity at the SN

  2. Extreme Host Galaxy Growth in Powerful Early-epoch Radio Galaxies

    NARCIS (Netherlands)

    Barthel, Peter; Haas, Martin; Leipski, Christian; Wilkes, Belinda

    2012-01-01

    During the first half of the universe's life, a heyday of star formation must have occurred because many massive galaxies are in place after that epoch in cosmic history. Our observations with the revolutionary Herschel Space Observatory reveal vigorous optically obscured star formation in the

  3. The Host Galaxy and Redshift of the Repeating Fast Radio Burst FRB 121102

    Energy Technology Data Exchange (ETDEWEB)

    Tendulkar, S. P.; Kaspi, V. M. [Department of Physics and McGill Space Institute, McGill University, 3600 University Street, Montreal, QC H3A 2T8 (Canada); Bassa, C. G.; Adams, E. A. K.; Hessels, J. W. T.; Maddox, N. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, NL-7990 AA Dwingeloo (Netherlands); Cordes, J. M.; Chatterjee, S. [Cornell Center for Astrophysics and Planetary Science and Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Bower, G. C. [Academia Sinica Institute of Astronomy and Astrophysics, 645 N. A’ohoku Place, Hilo, HI 96720 (United States); Law, C. J. [Department of Astronomy and Radio Astronomy Lab, University of California, Berkeley, CA 94720 (United States); Bogdanov, S. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Burke-Spolaor, S.; Butler, B. J.; Demorest, P. [National Radio Astronomy Observatory, Socorro, NM 87801 (United States); Lazio, T. J. W. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Marcote, B.; Paragi, Z. [Joint Institute for VLBI ERIC, Postbus 2, NL-7990 AA Dwingeloo (Netherlands); McLaughlin, M. A. [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 (United States); Ransom, S. M. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Scholz, P., E-mail: shriharsh@physics.mcgill.ca, E-mail: bassa@astron.nl [National Research Council of Canada, Herzberg Astronomy and Astrophysics, Dominion Radio Astrophysical Observatory, P.O. Box 248, Penticton, BC V2A 6J9 (Canada); and others

    2017-01-10

    The precise localization of the repeating fast radio burst (FRB 121102) has provided the first unambiguous association (chance coincidence probability p ≲ 3 × 10{sup −4}) of an FRB with an optical and persistent radio counterpart. We report on optical imaging and spectroscopy of the counterpart and find that it is an extended (0.″6–0.″8) object displaying prominent Balmer and [O iii] emission lines. Based on the spectrum and emission line ratios, we classify the counterpart as a low-metallicity, star-forming, m{sub r′} = 25.1 AB mag dwarf galaxy at a redshift of z = 0.19273(8), corresponding to a luminosity distance of 972 Mpc. From the angular size, the redshift, and luminosity, we estimate the host galaxy to have a diameter ≲4 kpc and a stellar mass of M {sub *} ∼ (4–7) × 10{sup 7} M {sub ⊙}, assuming a mass-to-light ratio between 2 to 3 M {sub ⊙} L {sub ⊙} {sup −1}. Based on the H α flux, we estimate the star formation rate of the host to be 0.4 M {sub ⊙} yr{sup −1} and a substantial host dispersion measure (DM) depth ≲324 pc cm{sup −3}. The net DM contribution of the host galaxy to FRB 121102 is likely to be lower than this value depending on geometrical factors. We show that the persistent radio source at FRB 121102’s location reported by Marcote et al. is offset from the galaxy’s center of light by ∼200 mas and the host galaxy does not show optical signatures for AGN activity. If FRB 121102 is typical of the wider FRB population and if future interferometric localizations preferentially find them in dwarf galaxies with low metallicities and prominent emission lines, they would share such a preference with long gamma-ray bursts and superluminous supernovae.

  4. The dark nature of GRB 130528A and its host galaxy

    Science.gov (United States)

    Jeong, S.; Castro-Tirado, A. J.; Bremer, M.; Winters, J. M.; Gorosabel, J.; Guziy, S.; Pandey, S. B.; Jelínek, M.; Sánchez-Ramírez, R.; Sokolov, Ilya V.; Orekhova, N. V.; Moskvitin, A. S.; Tello, J. C.; Cunniffe, R.; Lara-Gil, O.; Oates, S. R.; Pérez-Ramírez, D.; Bai, J.; Fan, Y.; Wang, C.; Park, I. H.

    2014-09-01

    Aims: We study the dark nature of GRB 130528A through multi-wavelength observations and conclude that the main reason for the optical darkness is local extinction inside of the host galaxy. Methods: Automatic observations were performed at the Burst Optical Observer and Transient Exploring System (BOOTES)-4/MET robotic telescope. We also triggered target of opportunity (ToO) observations at Observatorio de Sierra Nevada (OSN), IRAM Plateau de Bure Interferometer (PdBI) and Gran Telescopio Canarias (GTC + OSIRIS). The host galaxy photometric observations in optical to near-infrared (nIR) wavelengths were achieved through large ground-based aperture telescopes, such as 10.4 m Gran Telescopio Canarias (GTC), 4.2 m William Herschel Telescope (WHT), 6 m Bolshoi Teleskop Alt-azimutalnyi (BTA) telescope, and 2 m Liverpool Telescope (LT). Based on these observations, spectral energy distributions (SED) for the host galaxy and afterglow were constructed. Results: Thanks to millimetre (mm) observations at PdBI, we confirm the presence of a mm source within the XRT error circle that faded over the course of our observations and identify the host galaxy. However, we do not find any credible optical source within early observations with BOOTES-4/MET and 1.5 m OSN telescopes. Spectroscopic observation of this galaxy by GTC showed a single faint emission line that likely corresponds to [OII] 3727 Å at a redshift of 1.250 ± 0.001, implying a star formation rate (M⊙/yr) > 6.18 M⊙/yr without correcting for dust extinction. The probable line-of-sight extinction towards GRB 130528A is revealed through analysis of the afterglow SED, resulting in a value of A^GRBV≥ 0.9 at the rest frame; this is comparable to extinction levels found among other dark GRBs. The SED of the host galaxy is explained well (χ2/d.o.f. = 0.564) by a luminous (MB = -21.16), low-extinction (AV = 0, rest frame), and aged (2.6 Gyr) stellar population. We can explain this apparent contradiction in global and

  5. The host galaxy and environment of a bright QSO at z=7.54

    Science.gov (United States)

    Banados, Eduardo

    2017-08-01

    After almost a decade of intense search, our team has finally discovered a bright QSO well within the epoch of reionization, at z=7.54. This is by far the most distant QSO known (previous record: 7.08), at a cosmic age of 690 Myr, i.e., only 5% of our universe's current age. This is the first QSO whose spectrum shows clear evidence of an intergalactic medium that is >10% neutral and that reionization is underway. We propose deep HST ACS and WFC/IR imaging of this unique source with two main goals. (i) Unveil the rest-frame UV stellar light from the host galaxy to directly probe supermassive black hole/galaxy co-evolution at the highest accessible redshift. (ii) Search for galaxies physically associated with the QSO and test whether this object resides in one of the densest and most biased environment at the peak of the reionization epoch. HST observations are indispensable to address these topics for two reasons: (a) only HST provides the spatial resolution to separate the central bright light source from the underlying host galaxy and (b) at this record-redshift, only space-based imaging can provide the depths necessary to constrain the environment. These HST observations will provide key insights into the formation and evolution of the first super massive black holes, galaxies, and large-scale structure of the universe.

  6. X-RAY SELECTED AGN HOST GALAXIES ARE SIMILAR TO INACTIVE GALAXIES OUT TO z = 3: RESULTS FROM CANDELS/CDF-S

    International Nuclear Information System (INIS)

    Rosario, D. J.; Wuyts, S.; Nandra, K.; Mozena, M.; Faber, S. M.; Koo, D. C.; Koekemoer, A.; Ferguson, H.; Grogin, N.; McGrath, E.; Hathi, N. P.; Dekel, A.; Donley, J.; Dunlop, J. S.; Giavalisco, M.; Guo, Y.; Kocevski, D. D.; Laird, E.; Rangel, C.; Newman, J.

    2013-01-01

    We use multi-band spatially resolved photometry from the Cosmic Assembly Near-IR Deep Legacy Survey in the 4 Ms Chandra Deep Field-South to explore the nuclear and extended colors, color gradients, and stellar populations of the host galaxies of X-ray selected active galactic nuclei (AGNs) out to z = 3. Based on a study of their central light, we develop X-ray based criteria to exclude objects with strong AGN contamination. We use stellar masses from the FIREWORKS database to understand and account for stellar mass selection effects and carefully study, for the first time, the resolved host galaxy properties of AGNs at z ∼ 2 in their rest-frame optical light without substantial nuclear contamination. AGN hosts span a sizable range of stellar masses, colors, and color gradients at these redshifts. Their colors, color gradients, and stellar population properties are very similar to inactive galaxies of the same stellar mass. At z ∼ 1, we find a slightly narrower range in host colors compared to inactive galaxies, as well as hints of more recent star formation. These differences are weaker or non-existent among AGN hosts at z ∼ 2. We discuss the importance of AGN-driven feedback in the quenching of galaxies at z ∼> 1 and speculate on possible evolution in the relationship between black hole accretion and the host galaxy toward high redshifts.

  7. X-RAY SELECTED AGN HOST GALAXIES ARE SIMILAR TO INACTIVE GALAXIES OUT TO z = 3: RESULTS FROM CANDELS/CDF-S

    Energy Technology Data Exchange (ETDEWEB)

    Rosario, D. J.; Wuyts, S.; Nandra, K. [Max-Planck-Institute for Extraterrestrial Physics, Garching, D-85748 (Germany); Mozena, M.; Faber, S. M.; Koo, D. C. [Astronomy Department and UCO-Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Koekemoer, A.; Ferguson, H.; Grogin, N. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); McGrath, E. [Department of Physics, Colby College, Waterville, ME 04901 (United States); Hathi, N. P. [Observatories of the Carnegie Institution of Washington, Pasadena, CA 91101 (United States); Dekel, A. [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Donley, J. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Dunlop, J. S. [Institute for Astronomy, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Giavalisco, M.; Guo, Y. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003-9305 (United States); Kocevski, D. D. [Department of Physics and Astronomy, University of Kentucky, Lexington KY 40506-0055 (United States); Laird, E.; Rangel, C. [Department of Physics, Imperial College, London SW7 2AZ (United Kingdom); Newman, J. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); and others

    2013-01-20

    We use multi-band spatially resolved photometry from the Cosmic Assembly Near-IR Deep Legacy Survey in the 4 Ms Chandra Deep Field-South to explore the nuclear and extended colors, color gradients, and stellar populations of the host galaxies of X-ray selected active galactic nuclei (AGNs) out to z = 3. Based on a study of their central light, we develop X-ray based criteria to exclude objects with strong AGN contamination. We use stellar masses from the FIREWORKS database to understand and account for stellar mass selection effects and carefully study, for the first time, the resolved host galaxy properties of AGNs at z {approx} 2 in their rest-frame optical light without substantial nuclear contamination. AGN hosts span a sizable range of stellar masses, colors, and color gradients at these redshifts. Their colors, color gradients, and stellar population properties are very similar to inactive galaxies of the same stellar mass. At z {approx} 1, we find a slightly narrower range in host colors compared to inactive galaxies, as well as hints of more recent star formation. These differences are weaker or non-existent among AGN hosts at z {approx} 2. We discuss the importance of AGN-driven feedback in the quenching of galaxies at z {approx}> 1 and speculate on possible evolution in the relationship between black hole accretion and the host galaxy toward high redshifts.

  8. On the mass-metallicity relation, velocity dispersion and gravitational well depth of GRB host galaxies

    DEFF Research Database (Denmark)

    Arabsalmani, Maryam; Møller, Palle; Fynbo, Johan P. U.

    2015-01-01

    away from the metallicity in the centre of the galaxy, second the path of the sightline through different parts of the potential well of the dark matter halo will cause different velocity fields to be sampled. We report evidence suggesting that this second effect may have been detected....... the same underlying population. GRB host galaxies and QSO-DLAs are found to have different impact parameter distributions and we briefly discuss how this may affect statistical samples. The impact parameter distribution has two effects. First any metallicity gradient will shift the measured metallicity...

  9. THE HOST GALAXY PROPERTIES OF VARIABILITY SELECTED AGN IN THE PAN-STARRS1 MEDIUM DEEP SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Heinis, S.; Gezari, S.; Kumar, S. [Department of Astronomy, University of Maryland, College Park, MD (United States); Burgett, W. S.; Flewelling, H.; Huber, M. E.; Kaiser, N.; Wainscoat, R. J.; Waters, C. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

    2016-07-20

    We study the properties of 975 active galactic nuclei (AGNs) selected by variability in the Pan-STARRS1 Medium deep Survey. Using complementary multi-wavelength data from the ultraviolet to the far-infrared, we use spectral energy distribution fitting to determine the AGN and host properties at z < 1 and compare to a well-matched control sample. We confirm the trend previously observed: that the variability amplitude decreases with AGN luminosity, but we also observe that the slope of this relation steepens with wavelength, resulting in a “redder when brighter” trend at low luminosities. Our results show that AGNs are hosted by more massive hosts than control sample galaxies, while the rest frame dust-corrected NUV r color distribution of AGN hosts is similar to control galaxies. We find a positive correlation between the AGN luminosity and star formation rate (SFR), independent of redshift. AGN hosts populate the entire range of SFRs within and outside of the Main Sequence of star-forming galaxies. Comparing the distribution of AGN hosts and control galaxies, we show that AGN hosts are less likely to be hosted by quiescent galaxies and more likely to be hosted by Main Sequence or starburst galaxies.

  10. Hα3: an Hα imaging survey of HI selected galaxies from ALFALFA. VI. The role of bars in quenching star formation from z = 3 to the present epoch

    Science.gov (United States)

    Gavazzi, G.; Consolandi, G.; Dotti, M.; Fanali, R.; Fossati, M.; Fumagalli, M.; Viscardi, E.; Savorgnan, G.; Boselli, A.; Gutiérrez, L.; Hernández Toledo, H.; Giovanelli, R.; Haynes, M. P.

    2015-08-01

    A growing body of evidence indicates that the star formation rate per unit stellar mass (sSFR) decreases with increasing mass in normal main-sequence star-forming galaxies. Many processes have been advocated as being responsible for this trend (also known as mass quenching), e.g., feedback from active galactic nuclei (AGNs), and the formation of classical bulges. In order to improve our insight into the mechanisms regulating the star formation in normal star-forming galaxies across cosmic epochs, we determine a refined star formation versus stellar mass relation in the local Universe. To this end we use the Hα narrow-band imaging follow-up survey (Hα3) of field galaxies selected from the HI Arecibo Legacy Fast ALFA Survey (ALFALFA) in the Coma and Local superclusters. By complementing this local determination with high-redshift measurements from the literature, we reconstruct the star formation history of main-sequence galaxies as a function of stellar mass from the present epoch up to z = 3. In agreement with previous studies, our analysis shows that quenching mechanisms occur above a threshold stellar mass Mknee that evolves with redshift as ∝ (1 + z)2. Moreover, visual morphological classification of individual objects in our local sample reveals a sharp increase in the fraction of visually classified strong bars with mass, hinting that strong bars may contribute to the observed downturn in the sSFR above Mknee. We test this hypothesis using a simple but physically motivated numerical model for bar formation, finding that strong bars can rapidly quench star formation in the central few kpc of field galaxies. We conclude that strong bars contribute significantly to the red colors observed in the inner parts of massive galaxies, although additional mechanisms are likely required to quench the star formation in the outer regions of massive spiral galaxies. Intriguingly, when we extrapolate our model to higher redshifts, we successfully recover the observed

  11. The host galaxy of the gamma-ray narrow-line Seyfert 1 galaxy 1H 0323+342

    Energy Technology Data Exchange (ETDEWEB)

    León Tavares, J.; Chavushyan, V.; Puerari, I.; Patiño-Alvarez, V.; Carramiñana, A.; Carrasco, L.; Guichard, J.; Olguín-Iglesias, A.; Valdes, J. [Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE), Apartado Postal 51 y 216, 72000 Puebla (Mexico); Kotilainen, J. [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, FI-21500 Piikkiö (Finland); Añorve, C. [Facultad de Ciencias de la Tierra y del Espacio (FACITE) de la Universidad Autónoma de Sinaloa, Blvd. de la Americas y Av. Universitarios S/N, Ciudad Universitaria, C.P. 80010, Culiacán Sinaloa (Mexico); Cruz-González, I. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Ap. 70-264, 04510 DF (Mexico); Antón, S. [Instituto de Astrofísica de Andalucía-CSIC, E-18008 Granada (Spain); Karhunen, K.; Sanghvi, J., E-mail: leon.tavares@inaoep.mx [Tuorla Observatory, Department of Physics and Astronomy, University of Turku, FI-20100 Turku (Finland)

    2014-11-01

    We present optical and near-infrared (NIR) imaging data of the radio-loud, narrow-line Seyfert 1 galaxy 1H 0323+342, which shows intense and variable gamma-ray activity discovered by the Fermi satellite with the Large Area Telescope. Near-infrared and optical images are used to investigate the structural properties of the host galaxy of 1H 0323+342; this together with optical spectroscopy allows us to examine its black hole mass. Based on two-dimensional (2D) multiwavelength surface-brightness modeling, we find that statistically, the best model fit is a combination of a nuclear component and a Sérsic profile (n ∼ 2.8). However, the presence of a disk component (with a small bulge n ∼ 1.2) also remains a possibility and cannot be ruled out with the present data. Although at first glance a spiral-arm-like structure is revealed in our images, a 2D Fourier analysis of the imagery suggests that this structure corresponds to an asymmetric ring, likely associated with a recent violent dynamical interaction. We discuss our results in the context of relativistic jet production and galaxy evolution.

  12. The host galaxy of the gamma-ray narrow-line Seyfert 1 galaxy 1H 0323+342

    International Nuclear Information System (INIS)

    León Tavares, J.; Chavushyan, V.; Puerari, I.; Patiño-Alvarez, V.; Carramiñana, A.; Carrasco, L.; Guichard, J.; Olguín-Iglesias, A.; Valdes, J.; Kotilainen, J.; Añorve, C.; Cruz-González, I.; Antón, S.; Karhunen, K.; Sanghvi, J.

    2014-01-01

    We present optical and near-infrared (NIR) imaging data of the radio-loud, narrow-line Seyfert 1 galaxy 1H 0323+342, which shows intense and variable gamma-ray activity discovered by the Fermi satellite with the Large Area Telescope. Near-infrared and optical images are used to investigate the structural properties of the host galaxy of 1H 0323+342; this together with optical spectroscopy allows us to examine its black hole mass. Based on two-dimensional (2D) multiwavelength surface-brightness modeling, we find that statistically, the best model fit is a combination of a nuclear component and a Sérsic profile (n ∼ 2.8). However, the presence of a disk component (with a small bulge n ∼ 1.2) also remains a possibility and cannot be ruled out with the present data. Although at first glance a spiral-arm-like structure is revealed in our images, a 2D Fourier analysis of the imagery suggests that this structure corresponds to an asymmetric ring, likely associated with a recent violent dynamical interaction. We discuss our results in the context of relativistic jet production and galaxy evolution.

  13. Gas flow and dark matter in the inner parts of early-type barred galaxies - I. SPH simulations and comparison with the observed kinematics

    NARCIS (Netherlands)

    Perez, [No Value; Fux, R; Freeman, K

    This paper presents the dynamical simulations run in the potential derived from the light distribution of 5 late-type barred spiral galaxies (IC 5186, NGC 5728, NGC 7267, NGC 7483 and NGC 5505). The aim is to determine whether the mass distribution together with the hydrodynamical simulations can

  14. Active galactic nuclei vs. host galaxy properties in the COSMOS field

    Science.gov (United States)

    Lanzuisi, G.; Delvecchio, I.; Berta, S.; Brusa, M.; Comastri, A.; Gilli, R.; Gruppioni, C.; Marchesi, S.; Perna, M.; Pozzi, F.; Salvato, M.; Symeonidis, M.; Vignali, C.; Vito, F.; Volonteri, M.; Zamorani, G.

    2017-06-01

    Context. The coeval active galactic nuclei (AGN) and galaxy evolution, and the observed local relations between super massive black holes (SMBHs) and galaxy properties suggest some sort of connection or feedback between SMBH growth (I.e., AGN activity) and galaxy build-up (I.e., star formation history). Aims: We looked for correlations between average properties of X-ray detected AGN and their far-IR (FIR) detected, star forming host galaxies in order to find quantitative evidence for this connection, which has been highly debated in recent years. Methods: We exploited the rich multiwavelength data set (from X-ray to FIR) available in the COSMOS field for a large sample (692 sources) of AGN and their hosts in the redshift range 0.1 host galaxy properties, such as stellar mass (M∗) and star formation rate (SFR). Results: We find that the AGN 2-10 keV luminosity (LX) and the host 8-1000 μm star formation luminosity (LIRSF) are significantly correlated, even after removing the dependency of both quantities with redshift. However, the average host LIRSF has a flat distribution in bins of AGN LX, while the average AGN LX increases in bins of host LIRSF with logarithmic slope of 0.7 in the redshift range 0.4 host properties is found. On the other hand, we find that the average column density (NH) shows a clear positive correlation with the host M∗ at all redshifts, but not with the SFR (or LIRSF). This translates into a negative correlation with specific SFR at all redshifts. The same is true if the obscured fraction is computed. Conclusions: Our results are in agreement with the

  15. Energy from Active Galactic Nuclei and the Effects on Host Spiral Galaxies

    Science.gov (United States)

    Schilling, Amanda

    I have investigated the energy output of active galactic nuclei (AGN) in order to understand how these objects evolve and the impact they may have on host galaxies. First, I looked at a sample of 96 AGN at redshifts z 2, 3, and 4 which have imaging and thus luminosity measurements in the griz and JHK observed wavebands. For these galaxies, I have co-epochal data across those bands which accounted for variability in AGN luminosity. I used the luminosity measurements in the five bands to construct spectral energy distributions (SED) in the emitted optical-UV bands for each AGN. I compared the SED to assumptions previously made about quasars and looked for correlations between SED and other AGN and galaxy properties. Second, I used spectra of the broad line region (BLR) of Type 1 AGN to estimate the mass of the central supermassive black hole (MBH). I found a sample of Type 1 AGN that reside in spiral galaxies in order to explore the relationship between MBH and pitch angle (φ), a measurement of how tightly wound the spiral arms are. Type 1 AGN offer a method to estimate MBH at higher redshift than previous studies of the M BH-φ relation. I was able to look at the evolution in the MBH-φ relation which has implications for galaxy formation as well as AGN feedback.

  16. Galaxies

    International Nuclear Information System (INIS)

    1981-01-01

    Normal galaxies, radio galaxies, and Seyfert galaxies are considered. The large magellanic cloud and the great galaxy in Andromedia are highlighted. Quasars and BL lacertae objects are also discussed and a review of the spectral observations of all of these galaxies and celestial objects is presented

  17. Host galaxy subtraction of TeV candidate BL Lacertae objects

    Science.gov (United States)

    Nilsson, K.; Pasanen, M.; Takalo, L. O.; Lindfors, E.; Berdyugin, A.; Ciprini, S.; Pforr, J.

    2007-11-01

    Context: Photometric monitoring of active galactic nuclei is often complicated by the presence of a strong host galaxy component, which adds unwanted flux to the measurement and introduces a seeing-dependence to the flux that can plaque e.g. microvariability studies. We are currently monitoring a sample of 24 TeV candidate BL Lacertae objects, many of which exhibit a prominent host galaxy component, using differential aperture photometry. Aims: In order to study our light curves free from the above effects, we have derived the host galaxy flux in differential aperture photometry as a function of aperture radius and FWHM for 20 resolved sources in our sample. Methods: We created accurate surface brightness models of the targets and any significant nearby sources using high-resolution R-band imaging obtained at the Nordic Optical Telescope (NOT) and performed differential aperture photometry of the models over a grid of aperture radii and FWHM values. Results: The results are given as correction tables, that list the fluxes (in mJy) of all “contaminating” sources (host galaxy + significant nearby objects) as a function of aperture radius and FWHM. We found that the derived fluxes depend strongly on aperture radius, but the FWHM has only a minor effect (a few percent). We also discuss the implications of our findings to optical monitoring programs and potential sources of error in our derived fluxes. During this work we have also constructed new calibration star sequences for 9 objects and present the finding charts and calibrated magnitudes. Appendices A and B are only available in electronic form at http://www.aanda.org

  18. DEMOGRAPHICS OF THE GALAXIES HOSTING SHORT-DURATION GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Fong, W.; Berger, E.; Chornock, R.; Margutti, R.; Czekala, I.; Zauderer, B. A.; Laskar, T.; Servillat, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Levan, A. J.; Tunnicliffe, R. L. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Tanvir, N. R. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Fox, D. B. [Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802 (United States); Perley, D. A. [Cahill Center for Astronomy and Astrophysics, Room 232, California Institute of Technology, Pasadena, CA 91125 (United States); Cenko, S. B. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Persson, S. E.; Monson, A. J.; Kelson, D. D.; Birk, C.; Murphy, D. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Anglada, G. [Institut fuer Astrophysik, Friedrich-Hund-Platz 1, Universitaet Goettingen, D-37077 Goettingen (Germany)

    2013-05-20

    We present observations of the afterglows and host galaxies of three short-duration gamma-ray bursts (GRBs): 100625A, 101219A, and 110112A. We find that GRB 100625A occurred in a z = 0.452 early-type galaxy with a stellar mass of Almost-Equal-To 4.6 Multiplication-Sign 10{sup 9} M{sub Sun} and a stellar population age of Almost-Equal-To 0.7 Gyr, and GRB 101219A originated in a star-forming galaxy at z = 0.718 with a stellar mass of Almost-Equal-To 1.4 Multiplication-Sign 10{sup 9} M{sub Sun }, a star formation rate of Almost-Equal-To 16 M{sub Sun} yr{sup -1}, and a stellar population age of Almost-Equal-To 50 Myr. We also report the discovery of the optical afterglow of GRB 110112A, which lacks a coincident host galaxy to i {approx}> 26 mag, and we cannot conclusively identify any field galaxy as a possible host. From afterglow modeling, the bursts have inferred circumburst densities of Almost-Equal-To 10{sup -4}-1 cm{sup -3} and isotropic-equivalent gamma-ray and kinetic energies of Almost-Equal-To 10{sup 50}-10{sup 51} erg. These three events highlight the diversity of galactic environments that host short GRBs. To quantify this diversity, we use the sample of 36 Swift short GRBs with robust associations to an environment ({approx}1/2 of 68 short bursts detected by Swift to 2012 May) and classify bursts originating from four types of environments: late-type ( Almost-Equal-To 50%), early-type ( Almost-Equal-To 15%), inconclusive ( Almost-Equal-To 20%), and ''host-less'' (lacking a coincident host galaxy to limits of {approx}> 26 mag; Almost-Equal-To 15%). To find likely ranges for the true late- and early-type fractions, we assign each of the host-less bursts to either the late- or early-type category using probabilistic arguments and consider the scenario that all hosts in the inconclusive category are early-type galaxies to set an upper bound on the early-type fraction. We calculate most likely ranges for the late- and early-type fractions of

  19. A DETECTION OF MOLECULAR GAS EMISSION IN THE HOST GALAXY OF GRB 080517

    Energy Technology Data Exchange (ETDEWEB)

    Stanway, E. R.; Levan, A. J. [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL (United Kingdom); Tanvir, N. R.; Wiersema, K. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Van der Laan, T. P. R., E-mail: e.r.stanway@warwick.ac.uk [Institute de Radioastronomie Millimetrique (IRAM), 300 Rue de la Piscine, 38406 St. Martin d' Heres, Grenoble (France)

    2015-01-01

    We have observed the host galaxy of the low-redshift, low-luminosity Swift GRB 080517 at 105.8 GHz using the IRAM Plateau de Bure interferometer. We detect an emission line with integrated flux SΔν = 0.39 ± 0.05 Jy km s{sup –1}—consistent both spatially and in velocity with identification as the J = 1-0 rotational transition of carbon monoxide (CO) at the host galaxy redshift. This represents only the third long gamma-ray burst (GRB) host galaxy with molecular gas detected in emission. The inferred molecular gas mass, M{sub H{sub 2}}∼6.3×10{sup 8} M {sub ☉}, implies a gas consumption timescale of ∼40 Myr if star formation continues at its current rate. Similar short timescales appear characteristic of the long GRB population with CO observations to date, suggesting that the GRB in these sources occurs toward the end of their star formation episode.

  20. From Enigma to Tool: Gamma-Ray Burst Reveals Secrets of Host Galaxy

    Science.gov (United States)

    2001-05-01

    Five years ago, astronomers knew almost nothing about Gamma Ray Bursts. Now, a team of observers using the National Science Foundation's Very Large Array (VLA) radio telescope has used a gamma-ray burst as a powerful tool to unveil the nature of the galaxy in which it occurred, more than 7 billion light-years away. VLA Images of GRB980703 Host Galaxy "We believe that gamma-ray bursts may become one of the best available tools for studying the history of star formation in the universe," said Edo Berger, a graduate student at Caltech. Berger worked with Caltech astronomy professor Shri Kulkarni and Dale Frail, an astronomer at the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico, to study a gamma-ray burst first seen on July 3, 1998. The astronomers presented their results at the American Astronomical Society's meeting in Pasadena, CA. "For the first time, we've seen the host galaxy of a gamma-ray burst with a radio telescope," Berger said. "Previously, gamma-ray-burst host galaxies have been seen with optical telescopes, but detecting this galaxy with a radio telescope has given us new clues about the nature of the galaxy itself -- clues we couldn't have gotten any other way," he added. For example, based on optical-telescope studies, astronomers estimated that new stars are forming in the host galaxy at the rate of about the mass equivalent of 20 suns per year. However, data from the radio observations show that the actual star-formation rate is 25 times greater -- the mass equivalent of 500 suns per year. "With the VLA, we are seeing the entire region of star formation in this galaxy, including the areas so dusty that visible light can't get out," said Frail. Gamma-ray bursts are the most powerful explosions since the Big Bang. First discovered in 1967 by a satellite launched to monitor compliance with the atmospheric nuclear test ban treaty, gamma-ray bursts remained one of astronomy's premier mysteries for 30 years. For three decades

  1. Deficiency of normal galaxies among Markaryan galaxies

    International Nuclear Information System (INIS)

    Iyeveer, M.M.

    1986-01-01

    Comparison of the morphological types of Markaryan galaxies and other galaxies in the Uppsala catalog indicates a strong deficiency of normal ellipticals among the Markaryan galaxies, for which the fraction of type E galaxies is ≤ 1% against 10% among the remaining galaxies. Among the Markaryan galaxies, an excess of barred galaxies is observed - among the Markaryan galaxies with types Sa-Scd, approximately half or more have bars, whereas among the remaining galaxies of the same types bars are found in about 1/3

  2. Rapidly growing black holes and host galaxies in the distant Universe from the Herschel Radio Galaxy Evolution Project

    NARCIS (Netherlands)

    Drouart, G.; De Breuck, C.; Vernet, J.; Seymour, N.; Lehnert, M.; Barthel, P.; Bauer, F. E.; Ibar, E.; Galametz, A.; Haas, M.; Hatch, N.; Mullaney, J. R.; Nesvadba, N.; Rocca-Volmerange, B.; Röttgering, H. J. A.; Stern, D.; Wylezalek, D.

    2014-01-01

    We present results from a comprehensive survey of 70 radio galaxies at redshifts 1 2.5 are higher than the sSFR of typical star forming galaxies over the same redshift range, but are similar or perhaps lower than the galaxy population for radio galaxies at z<2.5. By comparing the sSFR and the

  3. The Post-starburst Evolution of Tidal Disruption Event Host Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    French, K. Decker; Zabludoff, Ann [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Arcavi, Iair [Department of Physics, University of California, Santa Barbara, CA 93106-9530 (United States)

    2017-02-01

    We constrain the recent star formation histories of the host galaxies of eight optical/UV-detected tidal disruption events (TDEs). Six hosts had quick starbursts of <200 Myr duration that ended 10–1000 Myr ago, indicating that TDEs arise at different times in their hosts’ post-starburst evolution. If the disrupted star formed in the burst or before, the post-burst age constrains its mass, generally excluding O, most B, and highly massive A stars. If the starburst arose from a galaxy merger, the time since the starburst began limits the coalescence timescale and thus the merger mass ratio to more equal than 12:1 in most hosts. This uncommon ratio, if also that of the central supermassive black hole (SMBH) binary, disfavors the scenario in which the TDE rate is boosted by the binary but is insensitive to its mass ratio. The stellar mass fraction created in the burst is 0.5%–10% for most hosts, not enough to explain the observed 30–200× boost in TDE rates, suggesting that the host’s core stellar concentration is more important. TDE hosts have stellar masses 10{sup 9.4}–10{sup 10.3} M {sub ☉}, consistent with the Sloan Digital Sky Survey volume-corrected, quiescent Balmer-strong comparison sample and implying SMBH masses of 10{sup 5.5}–10{sup 7.5} M {sub ☉}. Subtracting the host absorption line spectrum, we uncover emission lines; at least five hosts have ionization sources inconsistent with star formation that instead may be related to circumnuclear gas, merger shocks, or post-AGB stars.

  4. Using diffusion k-means for simple stellar population modeling of low S/N quasar host galaxy spectra

    Science.gov (United States)

    Mosby, Gregory; Tremonti, Christina A.; Hooper, Eric; Wolf, Marsha J.; Sheinis, Andrew; Richards, Joseph

    2016-01-01

    Quasar host galaxies (QHGs) represent a unique stage in galaxy evolution that can provide a glimpse into the relationship between an active supermassive black hole (SMBH) and its host galaxy. However, observing the hosts of high luminosity, unobscured quasars in the optical is complicated by the large ratio of quasar to host galaxy light. One strategy in optical spectroscopy is to use offset longslit observations of the host galaxy. This method allows the centers of QHGs to be analyzed apart from other regions of their host galaxies. But light from the accreting black hole's point spread function still enters the host galaxy observations, and where the contrast between the host and intervening quasar light is favorable, the host galaxy is faint, producing low signal-to-noise (S/N) data. This stymies traditional stellar population methods that might rely on high S/N features in galaxy spectra to recover key galaxy properties like its star formation history (SFH). In response to this challenge, we have developed a method of stellar population modeling using diffusion k-means (DFK) that can recover SFHs from rest frame optical data with S/N ~ 5 Å^-1. Specifically, we use DFK to cultivate a reduced stellar population basis set. This DFK basis set of four broad age bins is able to recover a range of SFHs. With an analytic description of the seeing, we can use this DFK basis set to simultaneously model the SFHs and the intervening quasar light of QHGs as well. We compare the results of this method with previous techniques using synthetic data and find that our new method has a clear advantage in recovering SFHs from QHGs. On average, the DFK basis set is just as accurate and decisively more precise. This new technique could be used to analyze other low S/N galaxy spectra like those from higher redshift or integral field spectroscopy surveys.This material is based upon work supported by the National Science Foundation under grant no. DGE -0718123 and the Advanced

  5. THE ROLE OF RADIATION PRESSURE IN THE NARROW LINE REGIONS OF SEYFERT HOST GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Davies, Rebecca L.; Dopita, Michael A.; Kewley, Lisa; Groves, Brent; Sutherland, Ralph; Hampton, Elise J.; Banfield, Julie [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Shastri, Prajval; Kharb, Preeti; Bhatt, Harish [Indian Institute of Astrophysics, Sarjapur Road, Bengaluru 560034 (India); Scharwächter, Julia [LERMA, Observatoire de Paris, PSL, CNRS, Sorbonne Universités, UPMC, F-75014 Paris (France); Jin, Chichuan [Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Zaw, Ingyin [New York University (Abu Dhabi), 70 Washington Square S, New York, NY 10012 (United States); James, Bethan [Institute of Astronomy, Cambridge University, Madingley Road, Cambridge CB3 0HA (United Kingdom); Juneau, Stéphanie [CEA-Saclay, DSM/IRFU/SAp, F-91191 Gif-sur-Yvette (France); Srivastava, Shweta, E-mail: Rebecca.Davies@anu.edu.au [Astronomy and Astrophysics Division, Physical Research Laboratory, Ahmedabad 380009 (India)

    2016-06-10

    We investigate the relative significance of radiation pressure and gas pressure in the extended narrow line regions (ENLRs) of four Seyfert galaxies from the integral field Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7). We demonstrate that there exist two distinct types of starburst-active galactic nucleus (AGN) mixing curves on standard emission line diagnostic diagrams, which reflect the balance between gas pressure and radiation pressure in the ENLR. In two of the galaxies the ENLR is radiation pressure dominated throughout and the ionization parameter remains constant (log U ∼ 0). In the other two galaxies radiation pressure is initially important, but gas pressure becomes dominant as the ionization parameter in the ENLR decreases from log U ∼ 0 to −3.2 ≲ log U ≲ −3.4. Where radiation pressure is dominant, the AGN regulates the density of the interstellar medium on kiloparsec scales and may therefore have a direct impact on star formation activity and/or the incidence of outflows in the host galaxy to scales far beyond the zone of influence of the black hole. We find that both radiation pressure dominated and gas pressure dominated ENLRs are dynamically active with evidence for outflows, indicating that radiation pressure may be an important source of AGN feedback even when it is not dominant over the entire ENLR.

  6. Spatially Resolved MaNGA Observations of the Host Galaxy of Superluminous Supernova 2017egm

    Science.gov (United States)

    Chen, Ting-Wan; Schady, Patricia; Xiao, Lin; Eldridge, J. J.; Schweyer, Tassilo; Lee, Chien-Hsiu; Yu, Po-Chieh; Smartt, Stephen J.; Inserra, Cosimo

    2017-11-01

    Superluminous supernovae (SLSNe) are found predominantly in dwarf galaxies, indicating that their progenitors have a low metallicity. However, the most nearby SLSN to date, SN 2017egm, occurred in the spiral galaxy NGC 3191, which has a relatively high stellar mass and correspondingly high metallicity. In this Letter, we present detailed analysis of the nearby environment of SN 2017egm using MaNGA IFU data, which provides spectral data on kiloparsec scales. From the velocity map we find no evidence that SN 2017egm occurred within some intervening satellite galaxy, and at the SN position most metallicity diagnostics yield a solar and above solar metallicity (12+{log}({{O}}/{{H}})˜ 8.8{--}9.1). Additionally, we measure a small Hα equivalent width (EW) at the SN position of just 34 Å, which is one of the lowest EWs measured at any SLSN or gamma-ray burst position, and indicative of the progenitor star being comparatively old. We also compare the observed properties of NGC 3191 with other SLSN host galaxies. The solar-metallicity environment at the position of SN 2017egm presents a challenge to our theoretical understanding, and our spatially resolved spectral analysis provides further constraints on the progenitors of SLSNe.

  7. ON THE DEPENDENCE OF TYPE Ia SNe LUMINOSITIES ON THE METALLICITY OF THEIR HOST GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Raya, Manuel E.; Mollá, Mercedes [Dpto.de Investigación Básica, C.I.E.M.A.T., Avda. Complutense 40, E-28040 Madrid (Spain); López-Sánchez, Ángel R. [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); Galbany, Lluís [Millennium Institute of Astrophysics MAS, Nuncio Monseñor Sótero Sanz 100, Providencia, 7500011 Santiago (Chile); Vílchez, José Manuel [Instituto de Astrofísica de Andalucía (CSIC), Apdo. 3004, E-18080 Granada (Spain); Rosell, Aurelio Carnero [Observatório Nacional, and LIneA Laboratório Interinstitucional de e-Astronomia, Rua Gal. José Cristino 77 Rio de Janeiro, RJ 20921-400 (Brazil); Domínguez, Inmaculada, E-mail: manuelemilio.moreno@ciemat.es [Departamento de Física Teórica y del Cosmos, Universidad de Granada, E-18071 Granada (Spain)

    2016-02-10

    The metallicity of the progenitor system producing a type Ia supernova (SN Ia) could play a role in its maximum luminosity, as suggested by theoretical predictions. We present an observational study to investigate if such a relationship exists. Using the 4.2 m William Herschel Telescope (WHT) we have obtained intermediate-resolution spectroscopy data of a sample of 28 local galaxies hosting SNe Ia, for which distances have been derived using methods independent of those based on SN Ia parameters. From the emission lines observed in their optical spectra, we derived the gas-phase oxygen abundance in the region where each SN Ia exploded. Our data show a trend, with an 80% of chance not being due to random fluctuation, between SNe Ia absolute magnitudes and the oxygen abundances of the host galaxies, in the sense that luminosities tend to be higher for galaxies with lower metallicities. This result seems likely to be in agreement with both the theoretically expected behavior and with other observational results. This dependence M{sub B}–Z might induce systematic errors when it is not considered when deriving SNe Ia luminosities and then using them to derive cosmological distances.

  8. Orbital and escape dynamics in barred galaxies - II. The 3D system: exploring the role of the normally hyperbolic invariant manifolds

    Science.gov (United States)

    Jung, Christof; Zotos, Euaggelos E.

    2016-12-01

    A three degrees of freedom (3-dof) barred galaxy model composed of a spherically symmetric nucleus, a bar, a flat disc and a spherically symmetric dark matter halo is used for investigating the dynamics of the system. We use colour-coded plots to demonstrate how the value of the semimajor axis of the bar influences the regular or chaotic dynamics of the 3-dof system. For distinguishing between ordered and chaotic motion, we use the Smaller ALingment Index (SALI) method, a fast yet very accurate tool. Undoubtedly, the most important elements of the dynamics are the normally hyperbolic invariant manifolds (NHIMs) located in the vicinity of the index 1 Lagrange points L2 and L3. These manifolds direct the flow of stars over the saddle points, while they also trigger the formation of rings and spirals. The dynamics in the neighbourhood of the saddle points is visualized by bifurcation diagrams of the Lyapunov orbits as well as by the restriction of the Poincaré map to the NHIMs. In addition, we reveal how the semimajor axis of the bar influences the structure of these manifolds which determine the final stellar structure (rings or spirals). Our numerical simulations suggest that in galaxies with weak bars the formation of R1 rings or R_1^' } pseudo-rings is favoured. In the case of galaxies with intermediate and strong bars, the invariant manifolds seem to give rise to R1R2 rings and twin spiral formations, respectively. We also compare our numerical outcomes with earlier related work and with observational data.

  9. A tale of two feedbacks: Star formation in the host galaxies of radio AGNs

    Energy Technology Data Exchange (ETDEWEB)

    Karouzos, Marios; Im, Myungshin; Jeon, Yiseul; Kim, Ji Hoon [CEOU-Astronomy Program, Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul (Korea, Republic of); Trichas, Markos [Airbus Defence and Space, Gunnels Wood Road, Stevenage SG1 2AS (United Kingdom); Goto, Tomo [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Malkan, Matt [Division of Astronomy and Astrophysics, 3-714 UCLA, CA 90095-1547 (United States); Ruiz, Angel [Inter-University Centre for Astronomy and Astrophysics (IUCAA), Post Bag 4, Ganeshkhind, 411 007 Pune (India); Lee, Hyung Mok; Kim, Seong Jin [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul (Korea, Republic of); Oi, Nagisa; Matsuhara, Hideo; Takagi, Toshinobu; Murata, K.; Wada, Takehiko; Wada, Kensuke [Institute of Space and Astronautical Science, JAXA, Yoshino-dai 3-1-1, Sagamihara, Kanagawa 229-8510 (Japan); Shim, Hyunjin [Department of Earth Science Education, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Hanami, Hitoshi [Physics Section, Faculty of Humanities, Iwate University, Ueda 3 chome, 18-34 Morioka, Morioka, Iwate 020-8550 (Japan); Serjeant, Stephen; White, Glenn J., E-mail: mkarouzos@astro.snu.ac.kr [Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes (United Kingdom); and others

    2014-04-01

    Several lines of argument support the existence of a link between activity at the nuclei of galaxies, in the form of an accreting supermassive black hole, and star formation activity in these galaxies. Radio jets have long been argued to be an ideal mechanism that allows active galactic nuclei (AGNs) to interact with their host galaxies and affect star formation. We use a sample of radio sources in the North Ecliptic Pole (NEP) field to study the nature of this putative link, by means of spectral energy distribution (SED) fitting. We employ the excellent spectral coverage of the AKARI infrared space telescope and the rich ancillary data available in the NEP to build SEDs extending from UV to far-IR wavelengths. We find a significant AGN component in our sample of relatively faint radio sources (host galaxy, independent of the radio luminosity. In contrast, for narrow redshift and AGN luminosity ranges, we find that increasing radio luminosity leads to a decrease in the specific star formation rate. The most radio-loud AGNs are found to lie on the main sequence of star formation for their respective redshifts. For the first time, we potentially see such a two-sided feedback process in the same sample. We discuss the possible suppression of star formation, but not total quenching, in systems with strong radio jets, that supports the maintenance nature of feedback from radio AGN jets.

  10. Quasar outflows at z ≥ 6: the impact on the host galaxies

    Science.gov (United States)

    Barai, Paramita; Gallerani, Simona; Pallottini, Andrea; Ferrara, Andrea; Marconi, Alessandro; Cicone, Claudia; Maiolino, Roberto; Carniani, Stefano

    2018-01-01

    We investigate quasar outflows at z ≥ 6 by performing zoom-in cosmological hydrodynamical simulations. By employing the smoothed particle hydrodynamics code GADGET-3, we zoom in the 2R200 region around a 2 × 1012 M⊙ halo at z = 6, inside a (500 Mpc)3 comoving volume. We compare the results of our active galactic nuclei (AGN) runs with a control simulation in which only stellar/SN feedback is considered. Seeding 105 M⊙ black holes (BHs) at the centres of 109 M⊙ haloes, we find the following results. BHs accrete gas at the Eddington rate over z = 9-6. At z = 6, our most-massive BH has grown to MBH = 4 × 109 M⊙. Fast (vr > 1000 km s-1), powerful (\\dot{M}_out ˜ 2000 M_{⊙} yr-1) outflows of shock-heated low-density gas form at z ∼ 7, and propagate up to hundreds kpc. Star formation is quenched over z = 8-6, and the total star formation rate (SFR surface density near the galaxy centre) is reduced by a factor of 5 (1000). We analyse the relative contribution of multiple physical process: (i) disrupting cosmic filamentary cold gas inflows, (ii) reducing central gas density, (iii) ejecting gas outside the galaxy; and find that AGN feedback has the following effects at z = 6. The inflowing gas mass fraction is reduced by ∼ 12 per cent, the high-density gas fraction is lowered by ∼ 13 per cent, and ∼ 20 per cent of the gas outflows at a speed larger than the escape velocity (500 km s-1). We conclude that quasar-host galaxies at z ≥ 6 are accreting non-negligible amount of cosmic gas, nevertheless AGN feedback quenches their star formation dominantly by powerful outflows ejecting gas out of the host galaxy halo.

  11. THE AFTERGLOW AND ULIRG HOST GALAXY OF THE DARK SHORT GRB 120804A

    Energy Technology Data Exchange (ETDEWEB)

    Berger, E.; Zauderer, B. A.; Margutti, R.; Laskar, T.; Fong, W.; Chornock, R.; Dupuy, T. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Levan, A.; Tunnicliffe, R. L. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Mangano, V. [INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica, Via U. La Malfa 153, I-90146 Palermo (Italy); Fox, D. B. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Tanvir, N. R. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Menten, K. M. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Hjorth, J. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Roth, K. [Gemini Observatory, 670 North Aohoku Place, Hilo, HI 96720 (United States)

    2013-03-10

    We present the optical discovery and subarcsecond optical and X-ray localization of the afterglow of the short GRB 120804A, as well as optical, near-IR, and radio detections of its host galaxy. X-ray observations with Swift/XRT, Chandra, and XMM-Newton extending to {delta}t Almost-Equal-To 19 days reveal a single power-law decline. The optical afterglow is faint, and comparison to the X-ray flux indicates that GRB 120804A is ''dark'', with a rest-frame extinction of A {sup host}{sub V} Almost-Equal-To 2.5 mag (at z = 1.3). The intrinsic neutral hydrogen column density inferred from the X-ray spectrum, N{sub H,{sub int}}(z = 1.3) Almost-Equal-To 2 Multiplication-Sign 10{sup 22} cm{sup -2}, is commensurate with the large extinction. The host galaxy exhibits red optical/near-IR colors. Equally important, JVLA observations at Almost-Equal-To 0.9-11 days reveal a constant flux density of F{sub {nu}}(5.8 GHz) = 35 {+-} 4 {mu}Jy and an optically thin spectrum, unprecedented for GRB afterglows, but suggestive instead of emission from the host galaxy. The optical/near-IR and radio fluxes are well fit with the scaled spectral energy distribution of the local ultraluminous infrared galaxy (ULIRG) Arp 220 at z Almost-Equal-To 1.3, with a resulting star formation rate of x Almost-Equal-To 300 M{sub Sun} yr{sup -1}. The inferred extinction and small projected offset (2.2 {+-} 1.2 kpc) are also consistent with the ULIRG scenario, as is the presence of a companion galaxy at the same redshift and with a separation of about 11 kpc. The limits on radio afterglow emission, in conjunction with the observed X-ray and optical emission, require a circumburst density of n {approx} 10{sup -3} cm{sup -3}, an isotropic-equivalent energy scale of E{sub {gamma},{sub iso}} Almost-Equal-To E{sub K,{sub iso}} Almost-Equal-To 7 Multiplication-Sign 10{sup 51} erg, and a jet opening angle of {theta}{sub j} {approx}> 11 Degree-Sign . The expected fraction of luminous infrared

  12. A Compact Group of Galaxies at z = 2.48 Hosting an AGN-driven Outflow

    Science.gov (United States)

    Shih, Hsin-Yi; Stockton, Alan

    2015-12-01

    We present observations of a remarkable compact group of galaxies at z = 2.48. Four galaxies, all within 40 kpc of each other, surround a powerful high-redshift radio source. This group comprises two compact red passive galaxies and a pair of merging galaxies. One of the red galaxies, with an apparent stellar mass of 3.6 × 1011M⊙ and an effective radius of 470 pc, is one of the most extreme examples of a massive quiescent compact galaxy found so far. One of the pair of merging galaxies hosts the active galactic nucleus (AGN) producing the large powerful radio structure. The merger is massive and enriched, consistent with the mass-metallicity relation expected at this redshift. Close to the merging nuclei, the emission lines exhibit broad and asymmetric profiles that suggest outflows powered either by a very young expanding radio jet or by AGN radiation. At ≳50 kpc from the system, we found a fainter extended-emission region that may be a part of a radio-jet-driven outflow. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The work is also based, in part, on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

  13. Galaxies

    International Nuclear Information System (INIS)

    1987-01-01

    The size and nature of any large-scale anisotropy in the three-dimensional distribution of galaxies is still little understood. Recent studies have indicated that large fluctuations in the matter distribution on a scale from tens up to several hundreds of megaparsecs may exist. Work at the South African Astronomical Observatory (SAAO) in recent years has made major contributions to studies of the large scale distribution of galaxies, as well as to solving the problems of the galactic and extragalactic distance scale. Other studies of galaxies undertaken at SAAO include: quasars in the fields of nearby galaxies; dwarf irregular galaxies; IRAS galaxies; Seyfert galaxies; 'hot spot' galaxies; supernovae in NGC 5128 and NGC 1559 and superclusters. 4 figs

  14. Galaxies

    International Nuclear Information System (INIS)

    1989-01-01

    In studies of the large scale structure of the universe there is a continuing need for extensive galaxy redshift determinations. Optically selected redshift surveys are of particular importance, since flux-limited samples record much higher space densities of galaxies than samples of similar size selected in other wavebands. A considerable amount of the South African Astronomical Observatory (SAAO) observing time is currently being devoted to carrying out a large southern galaxy redshift survey. A recently completed study, the Durham-SAAO redshift survey suggests that the mean density of matter is well below the critical limit for a closed universe and also that the universe may be homogenous at very large scales. Other research conducted by the SAAO include studies on: the distribution of galaxies; Seyfert galaxies; starburst and IRAS galaxies; interacting and compact galaxies; a re-evaluation of the Cepheid distance to NGC 300, and a search for quasars behind galaxies. 1 fig

  15. The host galaxies of ultra hard X-ray selected AGN

    Science.gov (United States)

    Koss, Michael J.

    One of the great mysteries surrounding active galactic nuclei (AGN) is their triggering mechanism. Since the discovery that almost all massive galaxies host nuclear supermassive black holes, it has become clear that a trigger mechanism is required to 'turn on' and continue to fuel the central black hole. While it is established that accretion processes are responsible for the energy emitted, the source of the accreting material is still controversial. Furthermore, the energy input from phases of black hole growth is thought to be a key regulator in the formation of galaxies and the establishment of various scaling relations. Theorists often invoke galaxy mergers as the violent mechanism to drive gas into the central regions and ignite luminous quasars, but among more common moderate luminosity AGN, there has been great controversy whether secular processes or mergers dominate AGN fueling. A survey in the ultra hard X-ray band (14--195 keV) is an important new way to answer the fundamental question of AGN fueling. This method is independent of selection effects such as dust extinction and obscuration that plague surveys at other wavelengths because of the ability of the primary continuum to easily pass through large columns of obscuring gas and dust (2 keV) imaging.

  16. The Smaller Alignment Index (SALI) applied in a study of stellar orbits in barred galaxies potential models using the LP-VIcode

    Science.gov (United States)

    Caritá, Lucas Antonio; Rodrigues, Irapuan; Puerari, Ivânio; Schiavo, Luiz Eduardo Camargo Aranha

    2018-04-01

    The Smaller Alignment Index (SALI) is a mathematical tool, not yet conventional, for chaos detection in the phase space of Hamiltonian Dynamical Systems. The SALI values has temporal behaviors very specific to ordered or chaotic motions, what makes the distinction between order and chaos easily observable in these systems. In this paper, this method will be applied to the stability study of stellar orbits immersed in gravitational potential of barred galaxies, since the motion of a test particle in a rotating barred galaxy model is given by a Hamiltonian function. Extracting four parameter sets from the Manos and Athanassoula (2011) work and elaborating a different initial conditions set for each case, we were able to introduce another point of view of their stability study for two degrees of freedom. We have also introduced two new extreme models that corroborates with the conclusions that more axisymmetric bars create an environment with less chaos and that more massive bars create an environment with more chaos. Separate studies were carried out for prograde and retrograde orbits that showed that the retrograde orbits seem more conducive to chaos. To perform all the orbits integrations we used the LP-VIcode program.

  17. The Spiral Host Galaxy of the Double Radio Source 0313-192

    Science.gov (United States)

    Keel, William C.; White, Raymond E., III; Owen, Frazer N.; Ledlow, Michael J.

    2006-12-01

    We present new Hubble Space Telescope (HST), Gemini South, and Chandra observations of the radio galaxy 0313-192, which hosts a 350 kpc double source and jets, even though previous data have suggested that it is a spiral galaxy. We measure the bulge scale and the luminosity, radial, and vertical profiles of disk starlight and consider the distributions of H II regions and absorbing dust. In each case the HST data confirm its classification as an edge-on spiral galaxy, the only such system known to produce such an extended radio source of this kind. The Gemini near-IR images and Chandra spectral fit reveal a strongly obscured central active galactic nucleus (AGN), seen through the entire interstellar medium path length of the disk and showing X-ray evidence of additional absorption from warm or dense material close to the central object. We consider several possible mechanisms for producing such a rare combination of AGN and host properties, some combination of which may be at work. These include an unusually luminous bulge (suggesting a black hole of mass ~8×108 Msolar), the orientation of the jets near the pole of the gas-rich disk, and some evidence of a weak gravitational interaction that has warped the disk and could have enhanced fueling of the central engine. We detect an X-ray counterpart of the kiloparsec-scale radio jet emerging to the south; jet/counterjet limits on both radio and X-ray regimes allow them to be symmetric if seen more than 15° from the plane of the sky, still consistent with the jet axes being within ~30° of the poles of the gas-rich galaxy disk. A linear or disklike emission-line structure is seen around the nucleus, inclined by ~20° to the stellar disk but nearly perpendicular to the jets; this may represent the aftermath of a galaxy encounter, in which gas is photoionized by a direct view of the nuclear continuum. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute

  18. Driving the growth of the earliest supermassive black holes with major mergers of host galaxies

    International Nuclear Information System (INIS)

    Tanaka, Takamitsu L

    2014-01-01

    The formation mechanism of supermassive black holes (SMBHs) in general, and of ∼10 9  m ⊙ SMBHs observed as luminous quasars at redshifts z>6 in particular, remains an open fundamental question. The presence of such massive BHs at such early times, when the Universe was less than a billion years old, implies that they grew via either super-Eddington accretion, or nearly uninterrupted gas accretion near the Eddington limit; the latter, at first glance, is at odds with empirical trends at lower redshifts, where quasar episodes associated with rapid BH growth are rare and brief. In this work, I examine whether and to what extent the growth of the z>6 quasar SMBHs can be explained within the standard quasar paradigm, in which major mergers of host galaxies trigger episodes of rapid gas accretion below or near the Eddington limit. Using a suite of Monte Carlo merger tree simulations of the assembly histories of 40 likely z>6 quasar host halos, I investigate (i) their growth and major merger rates out to z∼40, and (ii) how long the feeding episodes induced by host mergers must last in order to explain the observed z≳6 quasar population without super-Eddington accretion. The halo major merger rate scales roughly as ∝ (1+z) 5/2 , consistent with cosmological simulations at lower redshifts, with quasar hosts typically experiencing ≳10 major mergers between 15>z>6 (≈650 Myr), compared to ∼1 for typical massive galaxies at 3>z>0 (≈11 Gyr). The high rate of major mergers allows for nearly continuous SMBH growth if (for example) a merger triggers feeding for a duration comparable to the halo dynamical time. These findings suggest that the growth mechanisms of the earliest quasar SMBHs need not have been drastically different from their counterparts at lower redshifts. (paper)

  19. Deep Ly alpha imaging of two z=2.04 GRB host galaxy fields

    DEFF Research Database (Denmark)

    Fynbo, J.P.U.; Møller, Per; Thomsen, Bente

    2002-01-01

    the spectral slopes (f(lambda) proportional to lambda(beta)) of the two components to beta = 2.4 +/- 0.3 (east)and -1.4 +/- 0.2 (west). This implies that both components contain at most small amounts of dust, consistent with the observed strong Lyalpha emission. The western component has a slightly redder V......We report on the results of deep narrow-band Lyalpha and broad-band U and I imaging of the fields of two Gamma-Ray bursts at redshift z = 2.04 (GRB 000301C and GRB 000926). We find that the host galaxy of GRB 000926 is an extended (more than 2 arcsec), strong Lyalpha emitter with a rest...... - I colour than the eastern component, suggesting the presence of at least some dust. We do not detect the host galaxy of GRB 000301C in neither Lyalpha emission nor in U and I broad-band images. The strongest limit comes from combining the narrow and U-band imaging where we infer a limit of U(AB...

  20. Nuclear star clusters and the stellar spheroids of their host galaxies

    Science.gov (United States)

    Leigh, Nathan; Böker, Torsten; Knigge, Christian

    2012-08-01

    We combine published photometry for the nuclear star clusters (NSCs) and stellar spheroids of 51 low-mass, early-type galaxies in the Virgo cluster with empirical mass-to-light ratios, in order to complement previous studies that explore the dependence of NSC masses on various properties of their host galaxies. We confirm a roughly linear relationship between NSC mass and luminous host spheroid mass, albeit with considerable scatter (0.57 dex). In order to translate this into an MNSC-σ relation, we estimate velocity dispersions from the virial theorem, assuming that all galaxies in our sample share a common dark matter fraction and are dynamically relaxed. We then find that MNSC ˜ σ2.73 ± 0.29, with a slightly reduced scatter of 0.54 dex. This confirms recent results that the shape of the MCMO-σ relation is different for NSCs and super-massive black holes. We discuss this result in the context of the generalized idea of 'central massive objects' (CMOs). In order to assess which physical parameters drive the observed nuclear cluster masses, we also carry out a joint multivariate power-law fit to the data. In this, we allow the nuclear cluster mass to depend on spheroid mass and radius (and hence implicitly on velocity dispersion), as well as on the size of the globular cluster reservoir. When considered together, the dependences on MSph and RSph are roughly consistent with the virial theorem, and therefore MNSC ∝ σ2. However, the only statistically significant correlation appears to be a simple linear scaling between NSC mass and luminous spheroid mass. We proceed to directly compare the derived NSC masses with predictions for two popular models for NSC formation, namely (i) globular cluster infall due to dynamical friction and (ii) in situ formation during the early phases of galaxy formation that is regulated via momentum feedback from stellar winds and/or supernovae. Neither model can directly predict the observations, and we discuss possible

  1. THE ACS VIRGO CLUSTER SURVEY. XVII. THE SPATIAL ALIGNMENT OF GLOBULAR CLUSTER SYSTEMS WITH EARLY-TYPE HOST GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qiushi; Peng, Eric W. [Department of Astronomy, Peking University, Beijing 100871 (China); Blakeslee, John P.; Cote, Patrick; Ferrarese, Laura [Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Jordan, Andres [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Mei, Simona [University of Paris 7 Denis Diderot, F-75205 Paris Cedex 13 (France); West, Michael J., E-mail: peng@pku.edu.cn [Maria Mitchell Observatory, 4 Vestal Street, Nantucket, MA 02554 (United States)

    2013-06-01

    We study the azimuthal distribution of globular clusters (GCs) in early-type galaxies and compare them to their host galaxies using data from the ACS Virgo Cluster Survey. We find that in host galaxies with visible elongation ({epsilon} > 0.2) and intermediate to high luminosities (M{sub z} < -19), the GCs are preferentially aligned along the major axis of the stellar light. The red (metal-rich) GC subpopulations show strong alignment with the major axis of the host galaxy, which supports the notion that these GCs are associated with metal-rich field stars. The metal-rich GCs in lenticular galaxies show signs of being more strongly associated with disks rather than bulges. Surprisingly, we also find that the blue (metal-poor) GCs can also show the same correlation. If the metal-poor GCs are part of the early formation of the halo and built up through mergers, then our results support a picture where halo formation and merging occur anisotropically, and that the present-day major axis is an indicator of the preferred merging axis.

  2. A metallicity study of 1987A-like supernova host galaxies

    Science.gov (United States)

    Taddia, F.; Sollerman, J.; Razza, A.; Gafton, E.; Pastorello, A.; Fransson, C.; Stritzinger, M. D.; Leloudas, G.; Ergon, M.

    2013-10-01

    Context. The origin of the blue supergiant (BSG) progenitor of Supernova (SN) 1987A has long been debated, along with the role that its sub-solar metallicity played. We now have a sample of SN 1987A-like events that arise from the rare core collapse (CC) of massive (~20 M⊙) and compact (≲100 R⊙) BSGs. Aims: The metallicity of the explosion sites of the known BSG SNe is investigated, as well as the association of BSG SNe to star-forming regions. Methods: Both indirect and direct metallicity measurements of 13 BSG SN host galaxies are presented, and compared to those of other CC SN types. Indirect measurements are based on the known luminosity-metallicity relation and on published metallicity gradients of spiral galaxies. In order to provide direct metallicity measurements based on strong line diagnostics, we obtained spectra of each BSG SN host galaxy both at the exact SN explosion sites and at the positions of other H ii regions. We also observed these hosts with narrow Hα and broad R-band filters in order to produce continuum-subtracted Hα images. This allows us to measure the degree of association between BSG SNe and star-forming regions, and to compare it to that of other SN types. Results: BSG SNe are found to explode either in low-luminosity galaxies or at large distances from the nuclei of luminous hosts. Therefore, their indirectly measured metallicities are typically lower than those of SNe IIP and Ibc. This result is confirmed by the direct metallicity estimates, which show slightly sub-solar oxygen abundances (12 + log (O/H) ~ 8.3-8.4 dex) for the local environments of BSG SNe, similar to that of the Large Magellanic Cloud (LMC), where SN 1987A exploded. However, we also note that two objects of our sample (SNe 1998A and 2004em) were found at near solar metallicity. SNe IIb have a metallicity distribution similar to that of our BSG SNe. Finally, we find that the degree of association to star-forming regions is similar among BSG SNe, SNe IIP and

  3. Active Galaxy Host Properties from a New H I 21-cm Survey of the Swift BAT-detected AGN

    Science.gov (United States)

    Winter, Lisa M.; George, E. R.; Zauderer, B.; Darling, J.

    2013-01-01

    Many questions remain open on how central supermassive black holes and their host galaxies form and affect each other's evolution. In order to answer these questions, we need to understand the observational properties of a complete sample of active galaxies. To this end, we have been collecting and studying multi-wavelength spectroscopy of a unique sample of active galaxies selected in the very hard X-rays with the Swift Burst Alert Telescope. Here we present an analysis of the 21-cm H I spectra, which we observed with the 100-m Green Bank Telescope in 2012, for a sample of 95 Swift-detected AGN. With this complete sample, we show evidence for differences in the host cold gas mass content between obscured and unobscured AGN.

  4. Infrared and Optical Observations of GRB 030115 and its Extremely Red Host Galaxy: Implications for Dark Bursts

    International Nuclear Information System (INIS)

    Levan, Andrew; Fruchter, Andrew; Rhoads, James; Mobasher, Bahram; Tanvir, Nial; Gorosabel, Javier; Rol, Evert; Kouveliotou, Chryssa; Dell'Antonio, Ian; Merrill, Michael; Bergeron, Eddie; Castro Ceron, JosMar a; Masetti, Nicola; Vreeswijk, Paul; Antonelli, Angelo; Bersier, David; Castro-Tirado, Alberto; Fynbo, Johan; Garnavich, Peter; Holland, Stephen; Hjorth, Jens; Nugent, Peter; Pian, Elena; Smette, Alain; Thomsen, Bjarne; Thorsett, Stephen E.; Wijers, Ralph

    2006-01-01

    We present near-infrared (NIR) and optical observations of the afterglow of GRB 030115. Discovered in an infrared search at Kitt Peak5 hr after the burst trigger, this afterglow is the faintest ever observed in the R band at such an early epoch and exhibits very red colors, with R-K∼6. The optical magnitude of the afterglow of GRB 030115 is fainter than many upper limits for other bursts, suggesting that without early NIR observations it would have been classified as a 'dark' burst. Both the color and optical magnitude of the afterglow are likely due to dust extinction at moderate redshift z>2 and indicate that at least some optical afterglows are very faint due to dust along the line of sight. Multicolor Hubble Space Telescope observations were also taken of the host galaxy and the surrounding field. Photometric redshifts imply that the host and a substantial number of faint galaxies in the field are at z 2:5. The overdensity of galaxies is sufficiently great that GRB030115 may have occurred in a rich high-red shift cluster. The host galaxy shows extremely red colors (R-K = 5) and is the first GRB host to be classified as an extremely red object (ERO). Some of the galaxies surrounding the host also show very red colors, while the majority of the cluster are much bluer, indicating ongoing unobscured star formation. As it is thought that much of high-redshift star formation occurs in highly obscured environments, it may well be that GRB 030115 represents a transition object, between the relatively unobscured afterglows seen to date and a population of objects that are very heavily extinguished, even in the NIR

  5. Supermassive black holes in disc-dominated galaxies outgrow their bulges and co-evolve with their host galaxies

    Science.gov (United States)

    Simmons, B. D.; Smethurst, R. J.; Lintott, C.

    2017-09-01

    The deep connection between galaxies and their supermassive black holes is central to modern astrophysics and cosmology. The observed correlation between galaxy and black hole mass is usually attributed to the contribution of major mergers to both. We make use of a sample of galaxies whose disc-dominated morphologies indicate a major-merger-free history and show that such systems are capable of growing supermassive black holes at rates similar to quasars. Comparing black hole masses to conservative upper limits on bulge masses, we show that the black holes in the sample are typically larger than expected if processes creating bulges are also the primary driver of black hole growth. The same relation between black hole and total stellar mass of the galaxy is found for the merger-free sample as well as a sample that has experienced substantial mergers, indicating that major mergers do not play a significant role in controlling the co-evolution of galaxies and black holes. We suggest that more fundamental processes that contribute to galaxy assembly are also responsible for black hole growth.

  6. VizieR Online Data Catalog: Type 2 AGN host galaxies in Chandra-COSMOS (Suh+, 2017)

    Science.gov (United States)

    Suh, H.; Civano, F.; Hasinger, G.; Lusso, E.; Lanzuisi, G.; Marchesi, S.; Trakhtenbrot, B.; Allevato, V.; Cappelluti, N.; Capak, P. L.; Elvis, M.; Griffiths, R. E.; Laigle, C.; Lira, P.; Riguccini, L.; Rosario, D. J.; Salvato, M.; Schawinski, K.; Vignali, C.

    2018-01-01

    We investigate the star formation properties of a large sample of ~2300 X-ray-selected Type 2 Active Galactic Nuclei (AGNs) host galaxies out to z~3 in the Chandra COSMOS Legacy Survey in order to understand the connection between the star formation and nuclear activity. Making use of the existing multi-wavelength photometric data available in the COSMOS field, we perform a multi-component modeling from far-infrared to near-ultraviolet using a nuclear dust torus model, a stellar population model and a starburst model of the spectral energy distributions (SEDs). Through detailed analyses of SEDs, we derive the stellar masses and the star formation rates (SFRs) of Type 2 AGN host galaxies. The stellar mass of our sample is in the range of 93), and grow slowly through secular fueling processes hosting moderate-luminosity AGNs. (1 data file).

  7. ALMA Observations of the Host Galaxy of GRB 090423 at z = 8.23: Deep Limits on Obscured Star Formation 630 Million Years after the Big Bang

    Science.gov (United States)

    Berger, E.; Zauderer, B. A.; Chary, R.-R.; Laskar, T.; Chornock, R.; Tanvir, N. R.; Stanway, E. R.; Levan, A. J.; Levesque, E. M.; Davies, J. E.

    2014-12-01

    We present rest-frame far-infrared (FIR) and optical observations of the host galaxy of GRB 090423 at z = 8.23 from the Atacama Large Millimeter Array (ALMA) and the Spitzer Space Telescope, respectively. The host remains undetected to 3σ limits of F ν(222 GHz) Space Telescope rest-frame ultraviolet (UV) observations is SFRUV ~ 4 (Lyman break galaxies, Lyα emitters, and submillimeter galaxies) and find that our limit on the FIR luminosity is the most constraining to date, although the field galaxies have much larger rest-frame UV/optical luminosities than the host of GRB 090423 by virtue of their selection techniques. We conclude that GRB host galaxies at z >~ 4, especially those with measured interstellar medium metallicities from afterglow spectroscopy, are an attractive sample for future ALMA studies of high redshift obscured star formation.

  8. Spatially Resolved Patchy Ly α Emission within the Central Kiloparsec of a Strongly Lensed Quasar Host Galaxy at z = 2.8

    Energy Technology Data Exchange (ETDEWEB)

    Bayliss, Matthew B.; Bordoloi, Rongmon [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Sharon, Keren; Runnoe, Jessie; Johnson, Traci; Paterno-Mahler, Rachel [Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109 (United States); Acharyya, Ayan; Bian, Fuyan; Kewley, Lisa [RSAA, Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Gladders, Michael D. [Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Rigby, Jane R. [Astrophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Dahle, Hakon [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway); Florian, Michael, E-mail: mbayliss@mit.edu [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)

    2017-08-20

    We report the detection of extended Ly α emission from the host galaxy of SDSS J2222+2745, a strongly lensed quasar at z = 2.8. Spectroscopic follow-up clearly reveals extended Ly α in emission between two images of the central active galactic nucleus (AGN). We reconstruct the lensed quasar host galaxy in the source plane by applying a strong lens model to HST imaging and resolve spatial scales as small as ∼200 pc. In the source plane, we recover the host galaxy morphology to within a few hundred parsecs of the central AGN and map the extended Ly α emission to its physical origin on one side of the host galaxy at radii ∼0.5–2 kpc from the central AGN. There are clear morphological differences between the Ly α and rest-frame ultraviolet stellar continuum emission from the quasar host galaxy. Furthermore, the relative velocity profiles of quasar Ly α , host galaxy Ly α , and metal lines in outflowing gas reveal differences in the absorbing material affecting the AGN and host galaxy. These data indicate the presence of patchy local intervening gas in front of the central quasar and its host galaxy. This interpretation is consistent with the central luminous quasar being obscured across a substantial fraction of its surrounding solid angle, resulting in strong anisotropy in the exposure of the host galaxy to ionizing radiation from the AGN. This work demonstrates the power of strong-lensing-assisted studies to probe spatial scales that are currently inaccessible by other means.

  9. Steep extinction towards GRB 140506A reconciled from host galaxy observations: Evidence that steep reddening laws are local

    Science.gov (United States)

    Heintz, K. E.; Fynbo, J. P. U.; Jakobsson, P.; Krühler, T.; Christensen, L.; Watson, D.; Ledoux, C.; Noterdaeme, P.; Perley, D. A.; Rhodin, H.; Selsing, J.; Schulze, S.; Tanvir, N. R.; Møller, P.; Goldoni, P.; Xu, D.; Milvang-Jensen, B.

    2017-05-01

    We present the spectroscopic and photometric late-time follow-up of the host galaxy of the long-duration Swift γ-ray burst GRB 140506A at z = 0.889. The optical and near-infrared afterglow of this GRB had a peculiar spectral energy distribution (SED) with a strong flux-drop at 8000 Å (4000 Å rest-frame) suggesting an unusually steep extinction curve. By analysing the contribution and physical properties of the host galaxy, we here aim at providing additional information on the properties and origin of this steep, non-standard extinction. We find that the strong flux-drop in the GRB afterglow spectrum at contamination by the host galaxy light at short wavelengths so that the scenario with an extreme 2175 Å extinction bump can be excluded. We localise the GRB to be at a projected distance of approximately 4 kpc from the centre of the host galaxy. Based on emission-line diagnostics of the four detected nebular lines, Hα, Hβ, [O II] and [O III], we find the host to be a modestly star forming (SFR = 1.34 ± 0.04 M⊙ yr-1) and relatively metal poor (Z=0.35+0.15-0.11 Z⊙) galaxy with a large dust content, characterised by a measured visual attenuation of AV = 1.74 ± 0.41 mag. We compare the host to other GRB hosts at similar redshifts and find that it is unexceptional in all its physical properties. We model the extinction curve of the host-corrected afterglow and show that the standard dust properties causing the reddening seen in the Local Group are inadequate in describing the steep drop. We thus conclude that the steep extinction curve seen in the afterglow towards the GRB is of exotic origin and issightline-dependent only, further confirming that this type of reddening is present only at very local scales and that it is solely a consequence of the circumburst environment. Based on observations carried out under programme IDs 095.D-0043(A, C) and 095.A-0045(A) with the X-shooter spectrograph and the FOcal Reducer and low dispersion Spectrograph 2 (FORS2

  10. Galactic-scale Feedback Observed in the 3C 298 Quasar Host Galaxy

    Science.gov (United States)

    Vayner, Andrey; Wright, Shelley A.; Murray, Norman; Armus, Lee; Larkin, James E.; Mieda, Etsuko

    2017-12-01

    We present high angular resolution multiwavelength data of the 3C 298 radio-loud quasar host galaxy (z = 1.439) taken using the W.M. Keck Observatory OSIRIS integral field spectrograph (IFS) with adaptive optics, the Atacama Large Millimeter/submillimeter Array (ALMA), the Hubble Space Telescope (HST) WFC3, and the Very Large Array (VLA). Extended emission is detected in the rest-frame optical nebular emission lines Hβ, [O III], Hα, [N II], and [S II], as well as in the molecular lines CO (J = 3‑2) and (J = 5‑4). Along the path of the relativistic jets of 3C 298, we detect conical outflows in ionized gas emission with velocities of up to 1700 {km} {{{s}}}-1 and an outflow rate of 450–1500 {M}ȯ {{yr}}-1 extended over 12 kpc. Near the spatial center of the conical outflow, CO (J = 3‑2) emission shows a molecular gas disk with a rotational velocity of ±150 {km} {{{s}}}-1 and total molecular mass ({M}{{{H}}2}) of 6.6+/- 0.36× {10}9 {M}ȯ . On the blueshifted side of the molecular disk, we observe broad extended emission that is due to a molecular outflow with a rate of 2300 {M}ȯ {{yr}}-1 and depletion timescale of 3 Myr. We detect no narrow Hα emission in the outflow regions, suggesting a limit on star formation of 0.3 {M}ȯ {{yr}}-1 {{kpc}}-2. Quasar-driven winds are evacuating the molecular gas reservoir, thereby directly impacting star formation in the host galaxy. The observed mass of the supermassive black hole is {10}9.37{--9.56} {M}ȯ , and we determine a dynamical bulge mass of {M}{bulge}=1{--}1.7× {10}10\\tfrac{R}{1.6 {kpc}} {M}ȯ . The bulge mass of 3C 298 lies 2–2.5 orders of magnitude below the expected value from the local galactic bulge—supermassive black hole mass ({M}{bulge}{--}{M}{BH}) relationship. A second galactic disk observed in nebular emission is offset from the quasar by 9 kpc, suggesting that the system is an intermediate-stage merger. These results show that galactic-scale negative feedback is occurring early in the merger

  11. THE HOST GALAXY OF THE SUPER-LUMINOUS SN 2010gx AND LIMITS ON EXPLOSIVE {sup 56}Ni PRODUCTION

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ting-Wan; Smartt, Stephen J.; Kotak, Rubina; McCrum, Matt; Fraser, Morgan [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Bresolin, Fabio; Kudritzki, Rolf-Peter [Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Pastorello, Andrea [INAF-Osservatorio Astronomico di Padova, vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Valenti, Stefano [Las Cumbres Observatory Global Telescope Network, Inc., Santa Barbara, CA 93117 (United States)

    2013-02-01

    Super-luminous supernovae have a tendency to occur in faint host galaxies which are likely to have low mass and low metallicity. While these extremely luminous explosions have been observed from z = 0.1 to 1.55, the closest explosions allow more detailed investigations of their host galaxies. We present a detailed analysis of the host galaxy of SN 2010gx (z = 0.23), one of the best studied super-luminous type Ic supernovae. The host is a dwarf galaxy (M{sub g} = -17.42 {+-} 0.17) with a high specific star formation rate. It has a remarkably low metallicity of 12 + log (O/H) = 7.5 {+-} 0.1 dex as determined from the detection of the [O III] {lambda}4363 line. This is the first reliable metallicity determination of a super-luminous stripped-envelope supernova host. We collected deep multi-epoch imaging with Gemini + GMOS between 240 and 560 days after explosion to search for any sign of radioactive {sup 56}Ni, which might provide further insights on the explosion mechanism and the progenitor's nature. We reach griz magnitudes of m{sub AB} {approx} 26, but do not detect SN 2010gx at these epochs. The limit implies that any {sup 56}Ni production was similar to or below that of SN 1998bw (a luminous type Ic SN that produced around 0.4 M{sub Sun} of {sup 56}Ni). The low volumetric rates of these supernovae ({approx}10{sup -4} of the core-collapse population) could be qualitatively matched if the explosion mechanism requires a combination of low-metallicity (below 0.2 Z{sub Sun }), high progenitor mass (>60 M{sub Sun }) and high rotation rate (fastest 10% of rotators).

  12. THE HOST GALAXY OF THE SUPER-LUMINOUS SN 2010gx AND LIMITS ON EXPLOSIVE 56Ni PRODUCTION

    International Nuclear Information System (INIS)

    Chen, Ting-Wan; Smartt, Stephen J.; Kotak, Rubina; McCrum, Matt; Fraser, Morgan; Bresolin, Fabio; Kudritzki, Rolf-Peter; Pastorello, Andrea; Valenti, Stefano

    2013-01-01

    Super-luminous supernovae have a tendency to occur in faint host galaxies which are likely to have low mass and low metallicity. While these extremely luminous explosions have been observed from z = 0.1 to 1.55, the closest explosions allow more detailed investigations of their host galaxies. We present a detailed analysis of the host galaxy of SN 2010gx (z = 0.23), one of the best studied super-luminous type Ic supernovae. The host is a dwarf galaxy (M g = –17.42 ± 0.17) with a high specific star formation rate. It has a remarkably low metallicity of 12 + log (O/H) = 7.5 ± 0.1 dex as determined from the detection of the [O III] λ4363 line. This is the first reliable metallicity determination of a super-luminous stripped-envelope supernova host. We collected deep multi-epoch imaging with Gemini + GMOS between 240 and 560 days after explosion to search for any sign of radioactive 56 Ni, which might provide further insights on the explosion mechanism and the progenitor's nature. We reach griz magnitudes of m AB ∼ 26, but do not detect SN 2010gx at these epochs. The limit implies that any 56 Ni production was similar to or below that of SN 1998bw (a luminous type Ic SN that produced around 0.4 M ☉ of 56 Ni). The low volumetric rates of these supernovae (∼10 –4 of the core-collapse population) could be qualitatively matched if the explosion mechanism requires a combination of low-metallicity (below 0.2 Z ☉ ), high progenitor mass (>60 M ☉ ) and high rotation rate (fastest 10% of rotators).

  13. The effects of host galaxy properties on merging compact binaries detectable by LIGO

    Science.gov (United States)

    O'Shaughnessy, R.; Bellovary, J. M.; Brooks, A.; Shen, S.; Governato, F.; Christensen, C. R.

    2017-01-01

    Cosmological simulations of galaxy formation can produce present-day galaxies with a large range of assembly and star formation histories. A detailed study of the metallicity evolution and star formation history of such simulations can assist in predicting Laser Interferometer Gravitational-Wave Observatory (LIGO)-detectable compact object binary mergers. Recent simulations of compact binary evolution suggest that the compact object merger rate depends sensitively on the progenitor's metallicity. Rare low-metallicity star formation during galaxy assembly can produce more detected compact binaries than typical star formation. Using detailed simulations of galaxy and chemical evolution, we determine how sensitively the compact binary populations of galaxies with a similar present-day appearance depend on the details of their assembly. We also demonstrate by concrete example the extent to which dwarf galaxies overabundantly produce compact binary mergers, particularly binary black holes, relative to more massive galaxies. We discuss the implications for transient multimessenger astronomy with compact binary sources.

  14. Distance and Properties of NGC 4993 as the Host Galaxy of the Gravitational-wave Source GW170817

    Science.gov (United States)

    Im, Myungshin; Yoon, Yongmin; Lee, Seong-Kook J.; Lee, Hyung Mok; Kim, Joonho; Lee, Chung-Uk; Kim, Seung-Lee; Troja, Eleonora; Choi, Changsu; Lim, Gu; Ko, Jongwan; Shim, Hyunjin

    2017-11-01

    Recently, the optical counterpart of the gravitational-wave source GW170817 has been identified in the NGC 4993 galaxy. Together with evidence from observations in electromagnetic waves, the event has been suggested as a result of a merger of two neutron stars (NSs). We analyze the multi-wavelength data to characterize the host galaxy property and its distance to examine if the properties of NGC 4993 are consistent with this picture. Our analysis shows that NGC 4993 is a bulge-dominated galaxy with {r}{eff}˜ 2{--}3 {kpc} and a Sérsic index of n=3{--}4 for the bulge component. The spectral energy distribution from 0.15 to 24 μm indicates that this galaxy has no significant ongoing star formation, a mean stellar mass of (0.3{--}1.2)× {10}11 {M}⊙ , a mean stellar age greater than ˜3 Gyr, and a metallicity of about 20%-100% of solar abundance. Optical images reveal dust lanes and extended features that suggest a past merging activity. Overall, NGC 4993 has characteristics of normal, but slightly disturbed elliptical galaxies. Furthermore, we derive the distance to NGC 4993 with the fundamental plane relation using 17 parameter sets of 7 different filters and the central stellar velocity dispersion from the literature, finding an angular diameter distance of 37.7 ± 8.7 Mpc. NGC 4993 is similar to some host galaxies of short gamma-ray bursts (GRBs) but much different from those of long GRBs, supporting the picture of GW170817 as a result of the merger of two NSs.

  15. Orbital and escape dynamics in barred galaxies - III. The 3D system: correlations between the basins of escape and the NHIMs

    Science.gov (United States)

    Zotos, Euaggelos E.; Jung, Christof

    2018-01-01

    The escape dynamics of the stars in a barred galaxy composed of a spherically symmetric central nucleus, a bar, a flat thin disc and a dark matter halo component is investigated by using a realistic three degrees of freedom (3-d.o.f.) dynamical model. Modern colour-coded diagrams are used for distinguishing between bounded and escaping motion. In addition, the smaller alignment index method is deployed for determining the regular, sticky or chaotic nature of bounded orbits. We reveal the basins of escape corresponding to the escape through the two symmetrical escape channels around the Lagrange points L2 and L3 and also we relate them with the corresponding distribution of the escape times of the orbits. Furthermore, we demonstrate how the stable manifolds, around the index-1 saddle points, accurately define the fractal basin boundaries observed in the colour-coded diagrams. The development scenario of the fundamental vertical Lyapunov periodic orbit is thoroughly explored for obtaining a more complete view of the unfolding of the singular behaviour of the dynamics at the cusp values of the parameters. Finally, we examine how the combination of the most important parameters of the bar (such as the semimajor axis and the angular velocity) influences the observed stellar structures (rings and spirals), which are formed by escaping stars guided by the invariant manifolds near the saddle points.

  16. Detection of Lyman/alpha emission from a DLA galaxy

    DEFF Research Database (Denmark)

    Moller, P.; Fynbo, Johan Peter Uldall; Fall, S.M

    2004-01-01

    HIGH-REDSHIFT; BREAK GALAXIES; STARFORMATION; DISK GALAXIES; METAL ENRICHMENT; HOST GALAXY; ABSORPTION; ABSORBER; SYSTEMS; SPECTROSCOPY......HIGH-REDSHIFT; BREAK GALAXIES; STARFORMATION; DISK GALAXIES; METAL ENRICHMENT; HOST GALAXY; ABSORPTION; ABSORBER; SYSTEMS; SPECTROSCOPY...

  17. Deconstructing bulges in lenticular galaxies using CALIFA

    Science.gov (United States)

    Méndez-Abreu, J.; CALIFA Team

    2015-05-01

    Bulges play a key role in the evolution of disk galaxies and their influence on the fate of lenticular galaxies (S0s) is still more manifest. We present preliminary results on the photometric and kinematic properties of S0 bulges drawn from the CALIFA survey. We find that S0 galaxies usually deviate from their archetypal view of simple systems composed by a bulge and disk structure. In fact, most of S0 galaxies (˜65%) host bars or non-single exponential profiles, making compulsory the use of multi-component photometric decompositions to properly address the bulge properties. We confirm previous results present in the literature showing S0 galaxies as a complete photometric and kinematic sequence of galaxies.

  18. Massive stars formed in atomic hydrogen reservoirs: H i observations of gamma-ray burst host galaxies

    DEFF Research Database (Denmark)

    Michałowski, M. J.; Gentile, G.; Hjorth, J.

    2015-01-01

    Long gamma-ray bursts (GRBs), among the most energetic events in the Universe, are explosions of massive and short-lived stars, so they pinpoint locations of recent star formation. However, several GRB host galaxies have recently been found to be deficient in molecular gas (H2), believed......, implying high levels of atomic hydrogen (HI), which suggests that the connection between atomic gas and star formation is stronger than previously thought. In this case, it is possible that star formation is directly fuelled by atomic gas (or that the H1-to-H2 conversion is very efficient, which rapidly...... to be the fuel of star formation. Moreover, optical spectroscopy of GRB afterglows implies that the molecular phase constitutes only a small fraction of the gas along the GRB line of sight. Here we report the first ever 21 cm line observations of GRB host galaxies, using the Australia Telescope Compact Array...

  19. A population of massive, luminous galaxies hosting heavily dust-obscured gamma-ray bursts: Implications for the use of GRBs as tracers of cosmic star formation

    Energy Technology Data Exchange (ETDEWEB)

    Perley, D. A. [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Blvd., Pasadena, CA 91125 (United States); Levan, A. J. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Tanvir, N. R. [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Cenko, S. B.; Bloom, J. S.; Filippenko, A. V.; Morgan, A. N. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Hjorth, J.; Krühler, T.; Fynbo, J. P. U.; Milvang-Jensen, B. [Dark Cosmology Centre, Niels Bohr Institute, Copenhagen (Denmark); Fruchter, A.; Kalirai, J. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Jakobsson, P. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavík (Iceland); Prochaska, J. X. [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Silverman, J. M., E-mail: dperley@astro.caltech.edu [Department of Astronomy, University of Texas, Austin, TX 78712 (United States)

    2013-12-01

    We present observations and analysis of the host galaxies of 23 heavily dust-obscured gamma-ray bursts (GRBs) observed by the Swift satellite during the years 2005-2009, representing all GRBs with an unambiguous host-frame extinction of A{sub V} > 1 mag from this period. Deep observations with Keck, Gemini, Very Large Telescope, Hubble Space Telescope, and Spitzer successfully detect the host galaxies and establish spectroscopic or photometric redshifts for all 23 events, enabling us to provide measurements of the intrinsic host star formation rates, stellar masses, and mean extinctions. Compared to the hosts of unobscured GRBs at similar redshifts, we find that the hosts of dust-obscured GRBs are (on average) more massive by about an order of magnitude and also more rapidly star forming and dust obscured. While this demonstrates that GRBs populate all types of star-forming galaxies, including the most massive, luminous systems at z ≈ 2, at redshifts below 1.5 the overall GRB population continues to show a highly significant aversion to massive galaxies and a preference for low-mass systems relative to what would be expected given a purely star-formation-rate-selected galaxy sample. This supports the notion that the GRB rate is strongly dependent on metallicity, and may suggest that the most massive galaxies in the universe underwent a transition in their chemical properties ∼9 Gyr ago. We also conclude that, based on the absence of unobscured GRBs in massive galaxies and the absence of obscured GRBs in low-mass galaxies, the dust distributions of the lowest-mass and the highest-mass galaxies are relatively homogeneous, while intermediate-mass galaxies (∼10{sup 9} M {sub ☉}) have diverse internal properties.

  20. Galaxy And Mass Assembly (GAMA): Gas Fuelling of Spiral Galaxies in the Local Universe II. - Direct Measurement of the Dependencies on Redshift and Host Halo Mass of Stellar Mass Growth in Central Disk Galaxies

    Science.gov (United States)

    Grootes, M. W.; Dvornik, A.; Laureijs, R. J.; Tuffs, R. J.; Popescu, C. C.; Robotham, A. S. G.; Liske, J.; Brown, M. J. I.; Holwerda, B. W.; Wang, L.

    2018-03-01

    We present a detailed analysis of the specific star formation rate - stellar mass (sSFR - M*) of z ≤ 0.13 disk central galaxies using a morphologically selected mass-complete sample (M* ≥ 109.5M⊙). Considering samples of grouped and ungrouped galaxies, we find the sSFR - M* relations of disk-dominated central galaxies to have no detectable dependence on host dark-matter halo (DMH) mass, even where weak-lensing measurements indicate a difference in halo mass of a factor ≳ 5. We further detect a gradual evolution of the sSFR - M* relation of non-grouped (field) central disk galaxies with redshift, even over a Δz ≈ 0.04 (≈5 . 108yr) interval, while the scatter remains constant. This evolution is consistent with extrapolation of the "main-sequence-of-star-forming-galaxies" from previous literature that uses larger redshift baselines and coarser sampling. Taken together, our results present new constraints on the paradigm under which the SFR of galaxies is determined by a self-regulated balance between gas inflows and outflows, and consumption of gas by star-formation in disks, with the inflow being determined by the product of the cosmological accretion rate and a fuelling-efficiency - \\dot{M}_{b,halo}ζ. In particular, maintaining the paradigm requires \\dot{M}_{b,halo}ζ to be independent of the mass Mhalo of the host DMH. Furthermore, it requires the fuelling-efficiency ζ to have a strong redshift dependence (∝(1 + z)2.7 for M* = 1010.3M⊙ over z = 0 - 0.13), even though no morphological transformation to spheroids can be invoked to explain this in our disk-dominated sample. The physical mechanisms capable of giving rise to such dependencies of ζ on Mhalo and z for disks are unclear.

  1. The evolution of superluminous supernova LSQ14mo and its interacting host galaxy system

    Science.gov (United States)

    Chen, T.-W.; Nicholl, M.; Smartt, S. J.; Mazzali, P. A.; Yates, R. M.; Moriya, T. J.; Inserra, C.; Langer, N.; Krühler, T.; Pan, Y.-C.; Kotak, R.; Galbany, L.; Schady, P.; Wiseman, P.; Greiner, J.; Schulze, S.; Man, A. W. S.; Jerkstrand, A.; Smith, K. W.; Dennefeld, M.; Baltay, C.; Bolmer, J.; Kankare, E.; Knust, F.; Maguire, K.; Rabinowitz, D.; Rostami, S.; Sullivan, M.; Young, D. R.

    2017-06-01

    We present and analyse an extensive dataset of the superluminous supernova (SLSN) LSQ14mo (z = 0.256), consisting of a multi-colour light curve from -30 d to +70 d in the rest-frame (relative to maximum light) and a series of six spectra from PESSTO covering -7 d to +50 d. This is among the densest spectroscopic coverage, and best-constrained rising light curve, for a fast-declining hydrogen-poor SLSN. The bolometric light curve can be reproduced with a millisecond magnetar model with 4 M⊙ ejecta mass, and the temperature and velocity evolution is also suggestive of a magnetar as the power source. Spectral modelling indicates that the SN ejected 6 M⊙ of CO-rich material with a kinetic energy of 7 × 1051 erg, and suggests a partially thermalised additional source of luminosity between -2 d and +22 d. This may be due to interaction with a shell of material originating from pre-explosion mass loss. We further present a detailed analysis of the host galaxy system of LSQ14mo. PESSTO and GROND imaging show three spatially resolved bright regions, and we used the VLT and FORS2 to obtain a deep (five-hour exposure) spectra of the SN position and the three star-forming regions, which are at a similar redshift. The FORS2 spectrum at + 300 days shows no trace of SN emission lines and we place limits on the strength of [O I] from comparisons with other Ic supernovae. The deep spectra provides a unique chance to investigate spatial variations in the host star-formation activity and metallicity. The specific star-formation rate is similar in all three components,as is the presence of a young stellar population. However, the position of LSQ14mo exhibits a lower metallicity, with 12 + log (O/H) = 8.2 in both the R23 and N2 scales (corresponding to 0.3 Z⊙ ). We propose that the three bright regions in the host system are interacting, which could induce gas flows triggering star formation in low-metallicity regions. Based on observations at ESO, Program IDs: 191.D-0935, 094.D

  2. The formation and evolution of supermassive black holes and their host galaxies

    OpenAIRE

    Haehnelt, Martin G.; Kauffmann, Guinevere

    1999-01-01

    We discuss constraints on the assembly history of supermassive black holes from the observed remnant black holes in nearby galaxies and from the emission caused by accretion onto these black holes. We also summarize the results of a specific model for the evolution of galaxies and their central black holes which traces their hierachical build-up in CDM-like cosmogonies. The model assumes (i) that black holes, ellipticals and starburts form during major mergers of galaxies (ii) that the gas fr...

  3. Galaxy Disks

    NARCIS (Netherlands)

    van der Kruit, P. C.; Freeman, K. C.

    The disks of disk galaxies contain a substantial fraction of their baryonic matter and angular momentum, and much of the evolutionary activity in these galaxies, such as the formation of stars, spiral arms, bars and rings, and the various forms of secular evolution, takes place in their disks. The

  4. Rapid Coeval Black Hole and Host Galaxy Growth in MRC 1138-262 : The Hungry Spider

    NARCIS (Netherlands)

    Seymour, N.; Altieri, B.; De Breuck, C.; Barthel, P.; Coia, D.; Conversi, L.; Dannerbauer, H.; Dey, A.; Dickinson, M.; Drouart, G.; Galametz, A.; Greve, T. R.; Haas, M.; Hatch, N.; Ibar, E.; Ivison, R.; Jarvis, M.; Kovacs, A.; Kurk, J.; Lehnert, M.; Miley, G.; Nesvadba, N.; Rawlings, J. I.; Rettura, A.; Rottgering, H.; Rocca-Volmerange, B.; Sanchez-Portal, M.; Santos, J. S.; Stern, D.; Stevens, J.; Valtchanov, I.; Vernet, J.; Wylezalek, D.

    2012-01-01

    We present a detailed study of the infrared spectral energy distribution of the high-redshift radio galaxy MRC 1138-26 at z = 2.156, also known as the Spiderweb Galaxy. By combining photometry from Spitzer, Herschel, and LABOCA we fit the rest-frame 5-300 mu m emission using a two-component,

  5. THE SWIFT GRB HOST GALAXY LEGACY SURVEY. II. REST-FRAME NEAR-IR LUMINOSITY DISTRIBUTION AND EVIDENCE FOR A NEAR-SOLAR METALLICITY THRESHOLD

    Energy Technology Data Exchange (ETDEWEB)

    Perley, D. A. [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Blvd., Pasadena, CA 91125 (United States); Tanvir, N. R. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); Hjorth, J.; Fynbo, J. P. U.; Krühler, T. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 København Ø (Denmark); Laskar, T.; Berger, E. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Chary, R. [US Planck Data Center, MS220-6, Pasadena, CA 91125 (United States); Postigo, A. de Ugarte [Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, E-18008, Granada (Spain); Levan, A. J. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Michałowski, M. J. [Scottish Universities Physics Alliance, Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, EH9 3HJ (United Kingdom); Schulze, S., E-mail: dperley@dark-cosmology.dk [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, 7820436 Macul, Santiago 22 (Chile)

    2016-01-20

    We present rest-frame near-IR (NIR) luminosities and stellar masses for a large and uniformly selected population of gamma-ray burst (GRB) host galaxies using deep Spitzer Space Telescope imaging of 119 targets from the Swift GRB Host Galaxy Legacy Survey spanning 0.03 < z < 6.3, and we determine the effects of galaxy evolution and chemical enrichment on the mass distribution of the GRB host population across cosmic history. We find a rapid increase in the characteristic NIR host luminosity between z ∼ 0.5 and z ∼ 1.5, but little variation between z ∼ 1.5 and z ∼ 5. Dust-obscured GRBs dominate the massive host population but are only rarely seen associated with low-mass hosts, indicating that massive star-forming galaxies are universally and (to some extent) homogeneously dusty at high redshift while low-mass star-forming galaxies retain little dust in their interstellar medium. Comparing our luminosity distributions with field surveys and measurements of the high-z mass–metallicity relation, our results have good consistency with a model in which the GRB rate per unit star formation is constant in galaxies with gas-phase metallicity below approximately the solar value but heavily suppressed in more metal-rich environments. This model also naturally explains the previously reported “excess” in the GRB rate beyond z ≳ 2; metals stifle GRB production in most galaxies at z < 1.5 but have only minor impact at higher redshifts. The metallicity threshold we infer is much higher than predicted by single-star models and favors a binary progenitor. Our observations also constrain the fraction of cosmic star formation in low-mass galaxies undetectable to Spitzer to be small at z < 4.

  6. Formation of a Quasar Host Galaxy through a Wet Merger 1.4 Billion Years after the Big Bang

    Science.gov (United States)

    Riechers, Dominik A.; Walter, Fabian; Carilli, Christopher L.; Bertoldi, Frank; Momjian, Emmanuel

    2008-10-01

    We present high-resolution Very Large Array imaging of the molecular gas in the host galaxy of the high-redshift quasar BRI 1335-0417 (z = 4.41). Our CO(J = 2→ 1) observations have a linear resolution of 0.15' ' (1.0 kpc) and resolve the molecular gas emission both spatially and in velocity. The molecular gas in BRI 1335-0417 is extended on scales of 5 kpc, and shows a complex structure. At least three distinct components encompassing about two-thirds of the total molecular mass of 9.2 × 1010 M⊙ are identified in velocity space, which are embedded in a structure that harbors about one-third of the total molecular mass in the system. The brightest CO(J = 2→ 1) line emission region has a peak brightness temperature of 61 ± 9 K within 1 kpc diameter, which is comparable to the kinetic gas temperature as predicted from the CO line excitation. This is also comparable to the gas temperatures found in the central regions of nearby ultraluminous infrared galaxies, which are however much more compact than 1 kpc. The spatial and velocity structure of the molecular reservoir in BRI 1335-0417 is inconsistent with a simple gravitationally bound disk, but resembles a merging system. Our observations are consistent with a major, gas-rich ("wet") merger that both feeds an accreting supermassive black hole (causing the bright quasar activity), and fuels a massive starburst that builds up the stellar bulge in this galaxy. Our study of this z > 4 quasar host galaxy may thus be the most direct observational evidence that wet mergers at high redshift are related to AGN activity.

  7. The largely unconstrained multiphase nature of outflows in AGN host galaxies

    Science.gov (United States)

    Cicone, Claudia; Brusa, Marcella; Ramos Almeida, Cristina; Cresci, Giovanni; Husemann, Bernd; Mainieri, Vincenzo

    2018-03-01

    Observations and simulations show that outflows in active galactic nuclei contain gas in different phases. To understand their true impact on galaxy evolution, we advocate consistent and unbiased investigation of these multiphase winds in large active galactic nuclei samples.

  8. THE EFFECTS OF X-RAY FEEDBACK FROM ACTIVE GALACTIC NUCLEI ON HOST GALAXY EVOLUTION

    International Nuclear Information System (INIS)

    Hambrick, D. Clay; Ostriker, Jeremiah P.; Naab, Thorsten; Johansson, Peter H.

    2011-01-01

    Hydrodynamic simulations of galaxies with active galactic nuclei (AGNs) have typically employed feedback that is purely local, i.e., an injection of energy to the immediate neighborhood of the black hole (BH). We perform GADGET-2 simulations of massive elliptical galaxies with an additional feedback component: an observationally calibrated X-ray radiation field which emanates from the BH and heats gas out to large radii from the galaxy center. We find that including the heating and radiation pressure associated with this X-ray flux in our simulations enhances the effects which are commonly reported from AGN feedback. This new feedback model is twice as effective as traditional feedback at suppressing star formation, produces three times less star formation in the last 6 Gyr, and modestly lowers the final BH mass (30%). It is also significantly more effective than an X-ray background in reducing the number of satellite galaxies.

  9. A giant bar induced by a merger event at z = 0.4?

    Science.gov (United States)

    Peirani, S.; Hammer, F.; Flores, H.; Yang, Y.; Athanassoula, E.

    2009-03-01

    Context: Disk galaxies are the most common galaxy population in the local universe. However, the formation of their disks and structures - in particular their bars - is still a matter of debate. Aims: We present a physical model of the formation of J033239.72-275154.7, a galaxy observed at z=0.41 that contains a large, young bar of size 6 kpc. The study of this system is particularly interesting to the understanding of the connection between mergers and bars, as well as the properties and fate of this system in relation to disk galaxy formation. Methods: We compare the morphological and kinematic properties of J033239.72-275154.7, the latter obtained by the GIRAFFE spectrograph, to those derived from the merger of two spiral galaxies described by idealized N-body simulations, including a star formation prescription. Results: We found that the general morphological shape and most of the dynamical properties of the object can be well reproduced by a model in which the satellite is initially placed in a retrograde orbit and the mass ratio of the system is 1:3. In this scenario, a bar forms in the host galaxy after the first passage of the satellite, where a significant fraction of the available gas is consumed in an induced burst. In its later evolution, however, we find that J033239.72-275154.7, whose major progenitor was an Sab galaxy, will probably become a S0 galaxy. This is mainly due to the violent relaxation and the angular momentum loss experienced by the host galaxy during the merger process, which is caused by the adopted orbital parameters. This result suggests that the building of the Hubble sequence is influenced significantly by the last major collision. In the present case, the merger leads to a severe damage of the disk of the progenitor, leading to an evolution towards a more bulge-dominated galaxy.

  10. EmpiriciSN: Re-sampling Observed Supernova/Host Galaxy Populations Using an XD Gaussian Mixture Model

    Science.gov (United States)

    Holoien, Thomas W.-S.; Marshall, Philip J.; Wechsler, Risa H.

    2017-06-01

    We describe two new open-source tools written in Python for performing extreme deconvolution Gaussian mixture modeling (XDGMM) and using a conditioned model to re-sample observed supernova and host galaxy populations. XDGMM is new program that uses Gaussian mixtures to perform density estimation of noisy data using extreme deconvolution (XD) algorithms. Additionally, it has functionality not available in other XD tools. It allows the user to select between the AstroML and Bovy et al. fitting methods and is compatible with scikit-learn machine learning algorithms. Most crucially, it allows the user to condition a model based on the known values of a subset of parameters. This gives the user the ability to produce a tool that can predict unknown parameters based on a model that is conditioned on known values of other parameters. EmpiriciSN is an exemplary application of this functionality, which can be used to fit an XDGMM model to observed supernova/host data sets and predict likely supernova parameters using a model conditioned on observed host properties. It is primarily intended to simulate realistic supernovae for LSST data simulations based on empirical galaxy properties.

  11. EmpiriciSN: Re-sampling Observed Supernova/Host Galaxy Populations Using an XD Gaussian Mixture Model

    Energy Technology Data Exchange (ETDEWEB)

    Holoien, Thomas W.-S.; /Ohio State U., Dept. Astron. /Ohio State U., CCAPP /KIPAC, Menlo Park /SLAC; Marshall, Philip J.; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC

    2017-05-11

    We describe two new open-source tools written in Python for performing extreme deconvolution Gaussian mixture modeling (XDGMM) and using a conditioned model to re-sample observed supernova and host galaxy populations. XDGMM is new program that uses Gaussian mixtures to perform density estimation of noisy data using extreme deconvolution (XD) algorithms. Additionally, it has functionality not available in other XD tools. It allows the user to select between the AstroML and Bovy et al. fitting methods and is compatible with scikit-learn machine learning algorithms. Most crucially, it allows the user to condition a model based on the known values of a subset of parameters. This gives the user the ability to produce a tool that can predict unknown parameters based on a model that is conditioned on known values of other parameters. EmpiriciSN is an exemplary application of this functionality, which can be used to fit an XDGMM model to observed supernova/host data sets and predict likely supernova parameters using a model conditioned on observed host properties. It is primarily intended to simulate realistic supernovae for LSST data simulations based on empirical galaxy properties.

  12. Hubble space telescope observations of the afterglow, supernova, and host galaxy associated with the extremely bright GRB 130427A

    Energy Technology Data Exchange (ETDEWEB)

    Levan, A. J. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Tanvir, N. R.; Wiersema, K. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); Fruchter, A. S.; Hounsell, R. A.; Graham, J. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Hjorth, J.; Fynbo, J. P. U. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Pian, E. [INAF, Trieste Astronomical Observatory, via G.B. Tiepolo 11, I-34143 Trieste (Italy); Mazzali, P. [Astrophysics Research Institute, Liverpool John Moores University, IC2 Liverpool Science Park 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Perley, D. A. [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Blvd., Pasadena, CA 91125 (United States); Cano, Z. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik (Iceland); Cenko, S. B. [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Kouveliotou, C. [Science and Technology Office, ZP12, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Pe' er, A. [Department of Physics, University College Cork, Cork (Ireland); Misra, K., E-mail: a.j.levan@warwick.ac.uk [Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital-263 002 (India)

    2014-09-10

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst (GRB), GRB 130427A. At z = 0.34, this burst affords an excellent opportunity to study the supernova (SN) and host galaxy associated with an intrinsically extremely luminous burst (E {sub iso} > 10{sup 54} erg): more luminous than any previous GRB with a spectroscopically associated SN. We use the combination of the image quality, UV capability, and invariant point-spread function of HST to provide the best possible separation of the afterglow, host, and SN contributions to the observed light ∼17 rest-frame days after the burst, utilizing a host subtraction spectrum obtained one year later. Advanced Camera for Surveys grism observations show that the associated SN, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, v {sub ph} ∼ 15, 000 km s{sup –1}). The positions of the bluer features are better matched by the higher velocity SN 2010bh (v {sub ph} ∼ 30, 000 km s{sup –1}), but this SN is significantly fainter and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated ∼4 kpc from the nucleus of a moderately star forming (1 M {sub ☉} yr{sup –1}), possibly interacting disk galaxy. The absolute magnitude, physical size, and morphology of this galaxy, as well as the location of the GRB within it, are also strikingly similar to those of GRB 980425/SN 1998bw. The similarity of the SNe and environment from both the most luminous and least luminous GRBs suggests that broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  13. Hubble Space Telescope Observations of the Afterglow, Supernova and Host Galaxy Associated with the Extremely Bright GRB 130427A

    Science.gov (United States)

    Levan, A.J.; Tanvir, N. R.; Fruchter, A. S.; Hjorth, J.; Pian, E.; Mazzali, P.; Hounsell, R. A.; Perley, D. A.; Cano, Z.; Graham, J.; hide

    2014-01-01

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst, GRB 130427A. At z=0.34 this burst affords an excellent opportunity to study the supernova and host galaxy associated with an intrinsically extremely luminous burst (E(sub iso) greater than 10(exp 54) erg): more luminous than any previous GRB with a spectroscopically associated supernova. We use the combination of the image quality, UV capability and and invariant PSF of HST to provide the best possible separation of the afterglow, host and supernova contributions to the observed light approximately 17 rest-frame days after the burst utilising a host subtraction spectrum obtained 1 year later. Advanced Camera for Surveys (ACS) grism observations show that the associated supernova, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, vph approximately 15,000 kilometers per second). The positions of the bluer features are better matched by the higher velocity SN 2010bh (vph approximately 30,000 kilometers per second), but SN 2010bh (vph approximately 30,000 kilometers per second but this SN is significantly fainter, and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated approximately 4 kpc from the nucleus of a moderately star forming (1 Solar Mass yr(exp-1)), possibly interacting disc galaxy. The absolute magnitude, physical size and morphology of this galaxy, as well as the location of the GRB within it are also strikingly similar to those of GRB980425SN 1998bw. The similarity of supernovae and environment from both the most luminous and least luminous GRBs suggests broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  14. AGN-host galaxy connection: morphology and colours of X-ray selected AGN at z ≤ 2

    Science.gov (United States)

    Pović, M.; Sánchez-Portal, M.; Pérez García, A. M.; Bongiovanni, A.; Cepa, J.; Huertas-Company, M.; Lara-López, M. A.; Fernández Lorenzo, M.; Ederoclite, A.; Alfaro, E.; Castañeda, H.; Gallego, J.; González-Serrano, J. I.; González, J. J.

    2012-05-01

    Context. The connection between active galactic nuclei (AGN) and their host galaxies has been widely studied and found to be of great importance for providing answers to some fundamental questions related to AGN fuelling mechanisms, and both their formation and evolution. Aims: Using X-ray data and one of the deepest broad-band optical data sets available, we study how morphology and colours are related to X-ray properties for sources at redshifts z ≤ 2.0, using a sample of 262 AGN in the Subaru/XMM-Newton Deep Survey (SXDS). Methods: We performed our morphological classification using the galSVM code, which is a new method that is particularly suited to dealing with high-redshift sources. Colour-magnitude diagrams were studied in relationship to redshift, morphology, X-ray obscuration, and X-ray-to-optical flux ratio. We analysed the different regions in the colour-magnitude diagrams, and searched for correlations with the observed properties of AGN populations using models of their formation and evolution. Results: We confirm that a robust and reliable morphological classification of a general galaxy population at high redshift should be based on a multi-parametric approach. At least 50% of X-ray detected AGN at z ≤ 2.0 analysed in this work reside in spheroidal and bulge-dominated galaxies, while at least 18% have disk-dominated hosts. This suggests that different mechanisms may be responsible for triggering the nuclear activity. When analysing populations of X-ray detected AGN in both colour-magnitude and colour-stellar mass diagrams, the highest number of sources is found to reside in the green valley at redshifts ≈0.5-1.5. However, a larger number of low-luminosity AGN have been detected than in previous works owing to the substantial depth of the SXDS optical data. Whether AGN are hosted by early- or late-type galaxies, no clear relationship has been found with the optical colours (independently of redshift), as is typical of normal galaxies. Both

  15. Active galactic nuclei. From the central engine to the host galaxy

    International Nuclear Information System (INIS)

    Gilbert, Didier

    2008-01-01

    After some recalls on galaxies, on their classification, on the Universe expansion and on the Hubble law, this academic report addresses active galactic nuclei (AGN) by describing their anatomy (central black hole, accretion disk, jets and winds, Broad Line Region, Narrow Line Region, molecular torus and dusts, radio lobes). The author also presents the unified model. In the next part, he proposes an overview of active galaxies and active galactic nuclei by distinguishing galaxies with a strong stellar activity, radio-quiet and radio-loud active galactic nuclei. Examples are presented for each of these types. In the last part, the author draws perspectives for research in cosmology, and outlines questions which are still to be answered

  16. IDENTIFYING THE LOCATION IN THE HOST GALAXY OF THE SHORT GRB 111117A WITH THE CHANDRA SUBARCSECOND POSITION

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, T.; Troja, E. [Center for Research and Exploration in Space Science and Technology (CRESST), NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Aoki, K. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Guiriec, S.; Barthelmy, S. D. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Im, M.; Jeon, Y. [Center for the Exploration of the Origin of the Universe (CEOU), Department of Physics and Astronomy, Seoul National University, Seoul, 151-747 (Korea, Republic of); Leloudas, G.; Malesani, D.; De Ugarte Postigo, A.; Andersen, M. I. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Melandri, A.; D' Avanzo, P. [INAF-Osservatorio Astronomico di Brera, via Bianchi 46, I-23807 Merate (Italy); Urata, Y. [Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan (China); Xu, D. [Department of Particle Physics and Astronomy, The Weizmann Institute of Science, Rehovot 76100 (Israel); Gorosabel, J.; Sanchez-Ramirez, R. [Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomia s/n, E-18008 Granada (Spain); Bai, J. [Yunnan Astronomical Observatory, Chinese Academy of Sciences, Kunming, Yunnan Province, 650011 (China); Briggs, M. S. [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Foley, S. [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); and others

    2013-03-20

    We present our successful Chandra program designed to identify, with subarcsecond accuracy, the X-ray afterglow of the short GRB 111117A, which was discovered by Swift and Fermi. Thanks to our rapid target of opportunity request, Chandra clearly detected the X-ray afterglow, though no optical afterglow was found in deep optical observations. The host galaxy was clearly detected in the optical and near-infrared band, with the best photometric redshift of z=1.31{sub -0.23}{sup +0.46} (90% confidence), making it one of the highest known short gamma-ray burst (GRB) redshifts. Furthermore, we see an offset of 1.0 {+-} 0.2 arcsec, which corresponds to 8.4 {+-} 1.7 kpc, between the host and the afterglow position. We discuss the importance of using Chandra for obtaining subarcsecond X-ray localizations of short GRB afterglows to study GRB environments.

  17. CONNECTING GRBs AND ULIRGs: A SENSITIVE, UNBIASED SURVEY FOR RADIO EMISSION FROM GAMMA-RAY BURST HOST GALAXIES AT 0 < z < 2.5

    Energy Technology Data Exchange (ETDEWEB)

    Perley, D. A. [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Perley, R. A. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Hjorth, J.; Malesani, D. [Dark Cosmology Centre, Niels Bohr Institute, DK-2100 Copenhagen (Denmark); Michałowski, M. J. [Scottish Universities Physics Alliance, Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, EH9 3HJ (United Kingdom); Cenko, S. B. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Jakobsson, P. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavík (Iceland); Krühler, T. [European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago 19 (Chile); Levan, A. J. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Tanvir, N. R., E-mail: dperley@astro.caltech.edu [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom)

    2015-03-10

    Luminous infrared galaxies and submillimeter galaxies contribute significantly to stellar mass assembly and provide an important test of the connection between the gamma-ray burst (GRB) rate and that of overall cosmic star formation. We present sensitive 3 GHz radio observations using the Karl G. Jansky Very Large Array of 32 uniformly selected GRB host galaxies spanning a redshift range from 0 < z < 2.5, providing the first fully dust- and sample-unbiased measurement of the fraction of GRBs originating from the universe's most bolometrically luminous galaxies. Four galaxies are detected, with inferred radio star formation rates (SFRs) ranging between 50 and 300 M {sub ☉} yr{sup –1}. Three of the four detections correspond to events consistent with being optically obscured 'dark' bursts. Our overall detection fraction implies that between 9% and 23% of GRBs between 0.5 < z < 2.5 occur in galaxies with S {sub 3GHz} > 10 μJy, corresponding to SFR > 50 M {sub ☉} yr{sup –1} at z ∼ 1 or >250 M {sub ☉} yr{sup –1} at z ∼ 2. Similar galaxies contribute approximately 10%-30% of all cosmic star formation, so our results are consistent with a GRB rate that is not strongly biased with respect to the total SFR of a galaxy. However, all four radio-detected hosts have stellar masses significantly lower than IR/submillimeter-selected field galaxies of similar luminosities. We suggest that the GRB rate may be suppressed in metal-rich environments but independently enhanced in intense starbursts, producing a strong efficiency dependence on mass but little net dependence on bulk galaxy SFR.

  18. ALMA observations of the host galaxy of GRB 090423 at z = 8.23: deep limits on obscured star formation 630 million years after the big bang

    Energy Technology Data Exchange (ETDEWEB)

    Berger, E.; Zauderer, B. A.; Chary, R.-R.; Laskar, T.; Chornock, R.; Davies, J. E. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Tanvir, N. R. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Stanway, E. R.; Levan, A. J. [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL (United Kingdom); Levesque, E. M. [CASA, University of Colorado UCB 389, Boulder, CO 80309 (United States)

    2014-12-01

    We present rest-frame far-infrared (FIR) and optical observations of the host galaxy of GRB 090423 at z = 8.23 from the Atacama Large Millimeter Array (ALMA) and the Spitzer Space Telescope, respectively. The host remains undetected to 3σ limits of F {sub ν}(222 GHz) ≲ 33 μJy and F {sub ν}(3.6 μm) ≲ 81 nJy. The FIR limit is about 20 times fainter than the luminosity of the local ULIRG Arp 220 and comparable to the local starburst M 82. Comparing this with model spectral energy distributions, we place a limit on the infrared (IR) luminosity of L {sub IR}(8-1000 μm) ≲ 3 × 10{sup 10} L {sub ☉}, corresponding to a limit on the obscured star formation rate of SFR{sub IR}≲5 M {sub ☉} yr{sup –1}. For comparison, the limit on the unobscured star formation rate from Hubble Space Telescope rest-frame ultraviolet (UV) observations is SFR{sub UV} ≲ 1 M {sub ☉} yr{sup –1}. We also place a limit on the host galaxy stellar mass of M {sub *} ≲ 5 × 10{sup 7} M {sub ☉} (for a stellar population age of 100 Myr and constant star formation rate). Finally, we compare our millimeter observations to those of field galaxies at z ≳ 4 (Lyman break galaxies, Lyα emitters, and submillimeter galaxies) and find that our limit on the FIR luminosity is the most constraining to date, although the field galaxies have much larger rest-frame UV/optical luminosities than the host of GRB 090423 by virtue of their selection techniques. We conclude that GRB host galaxies at z ≳ 4, especially those with measured interstellar medium metallicities from afterglow spectroscopy, are an attractive sample for future ALMA studies of high redshift obscured star formation.

  19. Empirical Constraints on the Origin of Fast Radio Bursts: Volumetric Rates and Host Galaxy Demographics as a Test of Millisecond Magnetar Connection

    Science.gov (United States)

    Nicholl, M.; Williams, P. K. G.; Berger, E.; Villar, V. A.; Alexander, K. D.; Eftekhari, T.; Metzger, B. D.

    2017-07-01

    The localization of the repeating fast radio burst (FRB) 121102 to a low-metallicity dwarf galaxy at z = 0.193, and its association with a luminous quiescent radio source, suggests the possibility that FRBs originate from magnetars, formed by the unusual supernovae that occur in such galaxies. We investigate this possibility via a comparison of magnetar birth rates, the FRB volumetric rate, and host galaxy demographics. We calculate average volumetric rates of possible millisecond magnetar production channels, such as superluminous supernovae (SLSNe), long and short gamma-ray bursts (GRBs), and general magnetar production via core-collapse supernovae (CCSNe). For each channel, we also explore the expected host galaxy demographics using their known properties. We determine for the first time the number density of FRB emitters (the product of their volumetric birth rate and lifetime), {R}{FRB}τ ≈ {10}4 Gpc-3, assuming that FRBs are predominantly emitted from repetitive sources similar to FRB 121102 and adopting a beaming factor of 0.1. By comparing rates, we find that production via rare channels (SLSNe, GRBs) implies a typical FRB lifetime of ˜30-300 years, in good agreement with other lines of argument. The total energy emitted over this time is consistent with the available energy stored in the magnetic field. On the other hand, any relation to magnetars produced via normal CCSNe leads to a very short lifetime of ˜0.5 years, in conflict with both theory and observation. We demonstrate that due to the diverse host galaxy distributions of the different progenitor channels, many possible sources of FRB birth can be ruled out with ≲ 10 host galaxy identifications. Conversely, targeted searches of galaxies that have previously hosted decades-old SLSNe and GRBs may be a fruitful strategy for discovering new FRBs and related quiescent radio sources, and determining the nature of their progenitors.

  20. Evidence for merger remnants in early-type host galaxies of low-redshift QSOs

    Czech Academy of Sciences Publication Activity Database

    Bennert, N.; Canalizo, G.; Jungwiert, Bruno; Stockton, A.; Schweizer, F.; Peng, Ch.; Lacy, M.

    2008-01-01

    Roč. 677, č. 2 (2008), s. 846-857 ISSN 0004-637X R&D Projects: GA MŠk(CZ) LC06014 Institutional research plan: CEZ:AV0Z10030501 Keywords : galaxy mergers * quasars * photometry Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 6.331, year: 2008

  1. Spectacular Shells in the Host Galaxy of the QSO MC2 1635+119

    Czech Academy of Sciences Publication Activity Database

    Canalizo, G.; Bennert, N.; Jungwiert, Bruno; Stockton, A.; Schweizer, F.; Lacy, M.; Peng, Ch.

    2007-01-01

    Roč. 669, č. 2 (2007), s. 801-809 ISSN 0004-637X R&D Projects: GA MŠk(CZ) LC06014 Institutional research plan: CEZ:AV0Z10030501 Keywords : active galaxie s * interactions * evolution * quasars Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 6.405, year: 2007

  2. The metallicity and dust content of a redshift 5 gamma-ray burst host galaxy

    DEFF Research Database (Denmark)

    Sparre, M.; Hartoog, O. E.; Krühler, T.

    2014-01-01

    Observations of the afterglows of long gamma-ray bursts (GRBs) allow the study of star-forming galaxies across most of cosmic history. Here we present observations of GRB 111008A from which we can measure metallicity, chemical abundance patterns, dust-to-metals ratio and extinction of the GRB hos...

  3. R-band host galaxy contamination of TeV γ-ray blazar Mrk 501: effects of aperture size and seeing

    Science.gov (United States)

    Feng, Hai-Cheng; Liu, Hong-Tao; Zhao, Ying-He; Bai, Jin-Ming; Wang, Fang; Fan, Xu-Liang

    2018-02-01

    We simulated the R-band contribution of the host galaxy of TeV γ-ray BL Lac object Mrk 501 in different aperture sizes and seeing conditions. An intensive set of observations was acquired with the 1.02 m optical telescope, managed by Yunnan Observatories, from 2010 May 15 to 18. Based on the host subtraction data usually used in the literature, the subtraction of host galaxy contamination results in significant seeing-brightness correlations. These correlations would lead to illusive large amplitude variations at short timescales, which will mask the intrinsic microvariability, thus giving rise to difficulty in detecting the intrinsic microvariability. Both aperture size and seeing condition influence the flux measurements, but the aperture size impacts the result more significantly. Based on the parameters of an elliptical galaxy provided in the literature, we simulated the host contributions of Mrk 501 in different aperture sizes and seeing conditions. Our simulation data of the host galaxy obviously weaken these significant seeing-brightness correlations for the host-subtracted brightness of Mrk 501, and can help us discover the intrinsic short timescale microvariability. The pure nuclear flux is ∼8.0mJy in the R band, i.e., the AGN has a magnitude of R ∼ 13.96 mag.

  4. The Distance to NGC 4993: The Host Galaxy of the Gravitational-wave Event GW170817

    Science.gov (United States)

    Hjorth, Jens; Levan, Andrew J.; Tanvir, Nial R.; Lyman, Joe D.; Wojtak, Radosław; Schrøder, Sophie L.; Mandel, Ilya; Gall, Christa; Bruun, Sofie H.

    2017-10-01

    The historic detection of gravitational waves from a binary neutron star merger (GW170817) and its electromagnetic counterpart led to the first accurate (sub-arcsecond) localization of a gravitational-wave event. The transient was found to be ˜10″ from the nucleus of the S0 galaxy NGC 4993. We report here the luminosity distance to this galaxy using two independent methods. (1) Based on our MUSE/VLT measurement of the heliocentric redshift (z helio = 0.009783 ± 0.000023), we infer the systemic recession velocity of the NGC 4993 group of galaxies in the cosmic microwave background (CMB) frame to be v CMB = 3231 ± 53 km s-1. Using constrained cosmological simulations we estimate the line-of-sight peculiar velocity to be v pec = 307 ± 230 km s-1, resulting in a cosmic velocity of v cosmic = 2924 ± 236 km s-1 (z cosmic = 0.00980 ± 0.00079) and a distance of D z = 40.4 ± 3.4 Mpc assuming a local Hubble constant of H 0 = 73.24 ± 1.74 km s-1 Mpc-1. (2) Using Hubble Space Telescope measurements of the effective radius (15.″5 ± 1.″5) and contained intensity and MUSE/VLT measurements of the velocity dispersion, we place NGC 4993 on the Fundamental Plane (FP) of E and S0 galaxies. Comparing to a frame of 10 clusters containing 226 galaxies, this yields a distance estimate of D FP = 44.0 ± 7.5 Mpc. The combined redshift and FP distance is D NGC 4993 = 41.0 ± 3.1 Mpc. This “electromagnetic” distance estimate is consistent with the independent measurement of the distance to GW170817 as obtained from the gravitational-wave signal ({D}{GW}={43.8}-6.9+2.9 Mpc) and confirms that GW170817 occurred in NGC 4993.

  5. Active Galaxies

    DEFF Research Database (Denmark)

    Kilerci Eser, Ece

    Galaxy formation and evolution is one of the main research themes of modern astronomy. Active galaxies such as Active Galactic Nuclei (AGN) and Ultraluminous Infrared Galaxies (ULIRGs) are important evolutionary stages of galaxies. The ULIRG stage is mostly associated with galaxy mergers...... and interactions. During the interactions of gas-rich galaxies, the gas inflows towards the centers of the galaxies and can trigger both star formation and AGN activity. The ULIRG stage includes rapid star formation activity and fast black hole growth that is enshrouded by dust. Once the AGN emission...... one is related to the mass estimates of supermassive black holes (SMBHs). Mass estimates of SMBHs are important to understand the formation and evolution of SMBHs and their host galaxies. Black hole masses in Type 1 AGN are measured with the reverberation mapping (RM) technique. Reverberation mapping...

  6. Galaxy Formation

    DEFF Research Database (Denmark)

    Sparre, Martin

    Galaxy formation is an enormously complex discipline due to the many physical processes that play a role in shaping galaxies. The objective of this thesis is to study galaxy formation with two different approaches: First, numerical simulations are used to study the structure of dark matter and how...... galaxies form stars throughout the history of the Universe, and secondly it is shown that observations of gamma-ray bursts (GRBs) can be used to probe galaxies with active star formation in the early Universe. A conclusion from the hydrodynamical simulations is that the galaxies from the stateof...... is important, since it helps constraining chemical evolution models at high redshift. A new project studying how the population of galaxies hosting GRBs relate to other galaxy population is outlined in the conclusion of this thesis. The core of this project will be to quantify how the stellar mass function...

  7. Fitting and Phenomenology in Type IA Supernova Cosmology: Generalized Likelihood Analyses for Multiple Evolving Populations and Observations of Near-Infrared Lightcurves Including Host Galaxy Properties

    Science.gov (United States)

    Ponder, Kara A.

    In the late 1990s, Type Ia supernovae (SNeIa) led to the discovery that the Universe is expanding at an accelerating rate due to dark energy. Since then, many different tracers of acceleration have been used to characterize dark energy, but the source of cosmic acceleration has remained a mystery. To better understand dark energy, future surveys such as the ground-based Large Synoptic Survey Telescope and the space-based Wide-Field Infrared Survey Telescope will collect thousands of SNeIa to use as a primary dark energy probe. These large surveys will be systematics limited, which makes it imperative for our insight regarding systematics to dramatically increase over the next decade for SNeIa to continue to contribute to precision cosmology. I approach this problem by improving statistical methods in the likelihood analysis and collecting near infrared (NIR) SNeIa with their host galaxies to improve the nearby data set and search for additional systematics. Using more statistically robust methods to account for systematics within the likelihood function can increase accuracy in cosmological parameters with a minimal precision loss. Though a sample of at least 10,000 SNeIa is necessary to confirm multiple populations of SNeIa, the bias in cosmology is ˜ 2 sigma with only 2,500 SNeIa. This work focused on an example systematic (host galaxy correlations), but it can be generalized for any systematic that can be represented by a distribution of multiple Gaussians. The SweetSpot survey gathered 114 low-redshift, NIR SNeIa that will act as a crucial anchor sample for the future high redshift surveys. NIR observations are not as affected by dust contamination, which may lead to increased understanding of systematics seen in optical wavelengths. We obtained spatially resolved spectra for 32 SweetSpot host galaxies to test for local host galaxy correlations. For the first time, we probe global host galaxy correlations with NIR brightnesses from the current literature

  8. The Carnegie Supernova Project I. Methods to estimate host-galaxy reddening of stripped-envelope supernovae

    Science.gov (United States)

    Stritzinger, M. D.; Taddia, F.; Burns, C. R.; Phillips, M. M.; Bersten, M.; Contreras, C.; Folatelli, G.; Holmbo, S.; Hsiao, E. Y.; Hoeflich, P.; Leloudas, G.; Morrell, N.; Sollerman, J.; Suntzeff, N. B.

    2018-02-01

    We aim to improve upon contemporary methods to estimate host-galaxy reddening of stripped-envelope (SE) supernovae (SNe). To this end the Carnegie Supernova Project (CSP-I) SE SN photometry data release, consisting of nearly three dozen objects, is used to identify a minimally reddened sub-sample for each traditionally defined spectroscopic sub-type (i.e., SNe IIb, SNe Ib, SNe Ic). Inspection of the optical and near-infrared (NIR) colors and color evolution of the minimally reddened sub-samples reveals a high degree of homogeneity, particularly between 0 d to +20 d relative to B-band maximum. This motivated the construction of intrinsic color-curve templates, which when compared to the colors of reddened SE SNe, yields an entire suite of optical and NIR color excess measurements. Comparison of optical/optical vs. optical/NIR color excess measurements indicates the majority of the CSP-I SE SNe suffer relatively low amounts of reddening (i.e., E(B-V)host 0.20 mag) objects with the Fitzpatrick (1999, PASP, 111, 63) reddening law model provides robust estimates of the host visual-extinction AVhost and RVhost. In the case of the SE SNe with relatively low amounts of reddening, a preferred value of RVhost is adopted for each sub-type, resulting in estimates of AVhost through Fitzpatrick (1999) reddening law model fits to the observed color excess measurements. Our analysis suggests SE SNe reside in galaxies characterized by a range of dust properties. We also find evidence that SNe Ic are more likely to occur in regions characterized by larger RVhost values compared to SNe IIb/Ib and they also tend to suffer more extinction. The later finding is consistent with work in the literature suggesting SNe Ic tend to occur in regions of on-going star formation. Based on observations collected at Las Campanas Observatory.

  9. The environment and host haloes of the brightest z ˜ 6 Lyman-break galaxies

    Science.gov (United States)

    Hatfield, P. W.; Bowler, R. A. A.; Jarvis, M. J.; Hale, C. L.

    2018-04-01

    By studying the large-scale structure of the bright high-redshift Lyman-break galaxy (LBG) population it is possible to gain an insight into the role of environment in galaxy formation physics in the early Universe. We measure the clustering of a sample of bright (-22.7 model to measure their typical halo masses. We find that the clustering amplitude and corresponding HOD fits suggests that these sources are highly biased (b ˜ 8) objects in the densest regions of the high-redshift Universe. Coupled with the observed rapid evolution of the number density of these objects, our results suggest that the shape of high luminosity end of the luminosity function is related to feedback processes or dust obscuration in the early Universe - as opposed to a scenario where these sources are predominantly rare instances of the much more numerous MUV ˜ -19 population of galaxies caught in a particularly vigorous period of star formation. There is a slight tension between the number densities and clustering measurements, which we interpret this as a signal that a refinement of the model halo bias relation at high redshifts or the incorporation of quasi-linear effects may be needed for future attempts at modelling the clustering and number counts. Finally, the difference in number density between the fields (UltraVISTA has a surface density˜1.8 times greater than UDS) is shown to be consistent with the cosmic variance implied by the clustering measurements.

  10. THE OPTICALLY UNBIASED GRB HOST (TOUGH) SURVEY. VI. RADIO OBSERVATIONS AT z {approx}< 1 AND CONSISTENCY WITH TYPICAL STAR-FORMING GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Michalowski, M. J.; Dunlop, J. S. [SUPA (Scottish Universities Physics Alliance), Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Kamble, A.; Kaplan, D. L. [Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Hjorth, J.; Malesani, D.; Fynbo, J. P. U.; Kruehler, T. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Reinfrank, R. F. [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia); Bonavera, L. [Instituto de Fisica de Cantabria, CSIC-Universidad de Cantabria, Avda. de los Castros s/n, E-39005 Santander (Spain); Castro Ceron, J. M. [Department of Radio Astronomy, Madrid Deep Space Communications Complex (INTA-NASA/INSA), Ctra. M-531, km. 7, E-28.294 Robledo de Chavela (Madrid) (Spain); Ibar, E. [UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Garrett, M. A. [Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo (Netherlands); Jakobsson, P. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik (Iceland); Levan, A. J. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Massardi, M. [INAF-Istituto di Radioastronomia, via Gobetti 101, I-40129 Bologna (Italy); Pal, S. [ICRAR, University of Western Australia, 35 Stirling Highway, Crawley, WA (Australia); Sollerman, J. [Oskar Klein Centre, Department of Astronomy, AlbaNova, Stockholm University, SE-10691 Stockholm (Sweden); Tanvir, N. R. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Van der Horst, A. J., E-mail: mm@roe.ac.uk [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, Science Park 904, 1098XH Amsterdam (Netherlands); and others

    2012-08-20

    The objective of this paper is to determine the level of obscured star formation activity and dust attenuation in a sample of gamma-ray burst (GRB) hosts, and to test the hypothesis that GRB hosts have properties consistent with those of the general star-forming galaxy populations. We present a radio continuum survey of all z < 1 GRB hosts in The Optically Unbiased GRB Host (TOUGH) sample supplemented with radio data for all (mostly pre-Swift) GRB-SN hosts discovered before 2006 October. We present new radio data for 22 objects and have obtained a detection for three of them (GRB 980425, 021211, 031203; none in the TOUGH sample), increasing the number of radio-detected GRB hosts from two to five. The star formation rate (SFR) for the GRB 021211 host of {approx}825 M{sub Sun} yr{sup -1}, the highest ever reported for a GRB host, places it in the category of ultraluminous infrared galaxies. We found that at least {approx}63% of GRB hosts have SFR < 100 M{sub Sun} yr{sup -1} and at most {approx}8% can have SFR > 500 M{sub Sun} yr{sup -1}. For the undetected hosts the mean radio flux (<35 {mu}Jy 3{sigma}) corresponds to an average SFR < 15 M{sub Sun} yr{sup -1}. Moreover, {approx}> 88% of the z {approx}< 1 GRB hosts have ultraviolet dust attenuation A{sub UV} < 6.7 mag (visual attenuation A{sub V} < 3 mag). Hence, we did not find evidence for large dust obscuration in a majority of GRB hosts. Finally, we found that the distributions of SFRs and A{sub UV} of GRB hosts are consistent with those of Lyman break galaxies, H{alpha} emitters at similar redshifts, and of galaxies from cosmological simulations. The similarity of the GRB population with other star-forming galaxies is consistent with the hypothesis that GRBs, a least at z {approx}< 1, trace a large fraction of all star formation, and are therefore less biased indicators than once thought.

  11. DETERMINING TYPE Ia SUPERNOVA HOST GALAXY EXTINCTION PROBABILITIES AND A STATISTICAL APPROACH TO ESTIMATING THE ABSORPTION-TO-REDDENING RATIO R{sub V}

    Energy Technology Data Exchange (ETDEWEB)

    Cikota, Aleksandar [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching b. München (Germany); Deustua, Susana [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Marleau, Francine, E-mail: acikota@eso.org [Institute for Astro- and Particle Physics, University of Innsbruck, Technikerstrasse 25/8, A-6020 Innsbruck (Austria)

    2016-03-10

    We investigate limits on the extinction values of Type Ia supernovae (SNe Ia) to statistically determine the most probable color excess, E(B – V), with galactocentric distance, and use these statistics to determine the absorption-to-reddening ratio, R{sub V}, for dust in the host galaxies. We determined pixel-based dust mass surface density maps for 59 galaxies from the Key Insight on Nearby Galaxies: a Far-infrared Survey with Herschel (KINGFISH). We use SN Ia spectral templates to develop a Monte Carlo simulation of color excess E(B – V) with R{sub V} = 3.1 and investigate the color excess probabilities E(B – V) with projected radial galaxy center distance. Additionally, we tested our model using observed spectra of SN 1989B, SN 2002bo, and SN 2006X, which occurred in three KINGFISH galaxies. Finally, we determined the most probable reddening for Sa–Sap, Sab–Sbp, Sbc–Scp, Scd–Sdm, S0, and irregular galaxy classes as a function of R/R{sub 25}. We find that the largest expected reddening probabilities are in Sab–Sb and Sbc–Sc galaxies, while S0 and irregular galaxies are very dust poor. We present a new approach for determining the absorption-to-reddening ratio R{sub V} using color excess probability functions and find values of R{sub V} = 2.71 ± 1.58 for 21 SNe Ia observed in Sab–Sbp galaxies, and R{sub V} = 1.70 ± 0.38, for 34 SNe Ia observed in Sbc–Scp galaxies.

  12. Linking black hole growth with host galaxies: the accretion-stellar mass relation and its cosmic evolution

    Science.gov (United States)

    Yang, G.; Brandt, W. N.; Vito, F.; Chen, C.-T. J.; Trump, J. R.; Luo, B.; Sun, M. Y.; Xue, Y. Q.; Koekemoer, A. M.; Schneider, D. P.; Vignali, C.; Wang, J.-X.

    2018-04-01

    Previous studies suggest that the growth of supermassive black holes (SMBHs) may be fundamentally related to host-galaxy stellar mass (M⋆). To investigate this SMBH growth-M⋆ relation in detail, we calculate long-term SMBH accretion rate as a function of M⋆ and redshift [\\overlineBHAR(M_{\\star }, z)] over ranges of log (M⋆/M⊙) = 9.5-12 and z = 0.4-4. Our \\overlineBHAR(M_{\\star }, z) is constrained by high-quality survey data (GOODS-South, GOODS-North and COSMOS), and by the stellar mass function and the X-ray luminosity function. At a given M⋆, \\overlineBHAR is higher at high redshift. This redshift dependence is stronger in more massive systems [for log (M⋆/M⊙) ≈ 11.5, \\overlineBHAR is three decades higher at z = 4 than at z = 0.5], possibly due to AGN feedback. Our results indicate that the ratio between \\overlineBHAR and average star formation rate (\\overlineSFR) rises towards high M⋆ at a given redshift. This \\overlineBHAR/\\overlineSFR dependence on M⋆ does not support the scenario that SMBH and galaxy growth are in lockstep. We calculate SMBH mass history [MBH(z)] based on our \\overlineBHAR(M_{\\star }, z) and the M⋆(z) from the literature, and find that the MBH-M⋆ relation has weak redshift evolution since z ≈ 2. The MBH/M⋆ ratio is higher towards massive galaxies: it rises from ≈1/5000 at log M⋆ ≲ 10.5 to ≈1/500 at log M⋆ ≳ 11.2. Our predicted MBH/M⋆ ratio at high M⋆ is similar to that observed in local giant ellipticals, suggesting that SMBH growth from mergers is unlikely to dominate over growth from accretion.

  13. Identifying the Location in the Host Galaxy of Short GRB 1111l7A with the Chandra Sub- Arcsecond Position

    Science.gov (United States)

    Sakamoto, Takanori; Troja, E.; Aoki, K.; Guiriec, S.; Im, M.; Leloudas, G.; Malesani, D.; Melandri, A.; deUgartePostigo, A.; Urata, Y.; hide

    2012-01-01

    We present our successful program using Chandra for identifying the X-ray afterglow with sub-arcsecond accuracy for the short GRB 111117A d iscovered by Swift and Fermi. Thanks to our rapid target of opportuni ty request, Chandra clearly detected the X-ray afterglow, whereas no optical afterglow was found in deep optical observations. Instead, we clearly detect the host galaxy in optica; and also in near-infrared b ands. We found that the best photometric redshift fitofthe host is z = 1.31:(+0.46/-0.23) (90% confidence), making it one of the highest redshift short GRBs. Furthermore, we see an offset of 1.0+/-O.2 arcseco nds, which corresponds to 8.4+/-1.7 kpc aSBuming z= 1.31, between the host and the afterglow position. We discuss the importance of using Chandra for obtaining sub-arcsecond localization of the afterglow in X -rays for short GRBs to study GRB environments in great detail.

  14. The luminous, massive and solar metallicity galaxy hosting the Swift γ-ray burst GRB 160804A at z = 0.737

    Science.gov (United States)

    Heintz, K. E.; Malesani, D.; Wiersema, K.; Jakobsson, P.; Fynbo, J. P. U.; Savaglio, S.; Cano, Z.; Covino, S.; D'Elia, V.; Gomboc, A.; Hammer, F.; Kaper, L.; Milvang-Jensen, B.; Møller, P.; Piranomonte, S.; Selsing, J.; Rhodin, N. H. P.; Tanvir, N. R.; Thöne, C. C.; de Ugarte Postigo, A.; Vergani, S. D.; Watson, D.

    2018-02-01

    We here present the spectroscopic follow-up observations with VLT/X-shooter of the Swift long-duration gamma-ray burst GRB 160804A at z = 0.737. Typically, GRBs are found in low-mass, metal-poor galaxies that constitute the sub-luminous population of star-forming galaxies. For the host galaxy of the GRB presented here, we derive a stellar mass of log (M*/ M⊙) = 9.80 ± 0.07, a roughly solar metallicity (12 + log (O/H) = 8.74 ± 0.12) based on emission line diagnostics, and an infrared luminosity of M3.6/(1 + z) = -21.94 mag, but find it to be dust-poor (E(B - V) state of the absorbing and emitting gas are indicative of a galactic scale outflow expelled at the final stage of two merging galaxies.

  15. Type Ia Supernova Properties as a Function of the Distance to the Host Galaxy in the SDSS-II SN Survey

    Energy Technology Data Exchange (ETDEWEB)

    Galbany, Lluis [Institut de Fisica d' Altes Energies (IFAE), Barcelona (Spain); et al.

    2012-08-20

    We use type-Ia supernovae (SNe Ia) discovered by the SDSS-II SN Survey to search for dependencies between SN Ia properties and the projected distance to the host galaxy center, using the distance as a proxy for local galaxy properties (local star-formation rate, local metallicity, etc.). The sample consists of almost 200 spectroscopically or photometrically confirmed SNe Ia at redshifts below 0.25. The sample is split into two groups depending on the morphology of the host galaxy. We fit light-curves using both MLCS2k2 and SALT2, and determine color (AV, c) and light-curve shape (delta, x1) parameters for each SN Ia, as well as its residual in the Hubble diagram. We then correlate these parameters with both the physical and the normalized distances to the center of the host galaxy and look for trends in the mean values and scatters of these parameters with increasing distance. The most significant (at the 4-sigma level) finding is that the average fitted AV from MLCS2k2 and c from SALT2 decrease with the projected distance for SNe Ia in spiral galaxies. We also find indications that SNe in elliptical galaxies tend to have narrower light-curves if they explode at larger distances, although this may be due to selection effects in our sample. We do not find strong correlations between the residuals of the distance moduli with respect to the Hubble flow and the galactocentric distances, which indicates a limited correlation between SN magnitudes after standardization and local host metallicity.

  16. Gravitational lensing reveals extreme dust-obscured star formation in quasar host galaxies

    Science.gov (United States)

    Stacey, H. R.; McKean, J. P.; Robertson, N. C.; Ivison, R. J.; Isaak, K. G.; Schleicher, D. R. G.; van der Werf, P. P.; Baan, W. A.; Alba, A. Berciano; Garrett, M. A.; Loenen, A. F.

    2018-02-01

    We have observed 104 gravitationally-lensed quasars at z ˜ 1-4 with Herschel/SPIRE, the largest such sample ever studied. By targeting gravitational lenses, we probe intrinsic far-infrared (FIR) luminosities and star formation rates (SFRs) more typical of the population than the extremely luminous sources that are otherwise accessible. We detect 72 objects with Herschel/SPIRE and find 66 percent (69 sources) of the sample have spectral energy distributions (SEDs) characteristic of dust emission. For 53 objects with sufficiently constrained SEDs, we find a median effective dust temperature of 38^{+12}_{-5} K. By applying the radio-infrared correlation, we find no evidence for an FIR excess which is consistent with star-formation-heated dust. We derive a median magnification-corrected FIR luminosity of 3.6^{+4.8}_{-2.4} × 10^{11} L_{⊙} and median SFR of 120^{+160}_{-80} M_{⊙} yr^{-1} for 94 quasars with redshifts. We find ˜10 percent of our sample have FIR properties similar to typical dusty star-forming galaxies at z ˜ 2-3 and a range of SFRs statistically-significant difference in the FIR luminosities of quasars in our sample with a radio excess relative to the radio-infrared correlation. Synchrotron emission is found to dominate at FIR wavelengths for <15 percent of those sources classified as powerful radio galaxies.

  17. VizieR Online Data Catalog: Host galaxies of Type Ia SN from PTF (Pan+, 2014)

    Science.gov (United States)

    Pan, Y.-C.; Sullivan, M.; Maguire, K.; Hook, I. M.; Nugent, P. E.; Howell, D. A.; Arcavi, I.; Botyanszki, J.; Cenko, S. B.; Derose, J.; Fakhouri, H. K.; Gal-Yam, A.; Hsiao, E.; Kulkarni, S. R.; Laher, R. R.; Lidman, C.; Nordin, J.; Walker, E. S.; Xu, D.

    2014-11-01

    The SNe Ia studied in this paper were discovered by the PTF, a project which operated from 2009 to 2012 and used the CFH12k wide-field survey camera mounted on the Samuel Oschin 48 inch telescope (P48) at the Palomar Observatory. The observational cadences used to discover the SNe ranged from hours up to ~5d. SN candidates were identified in image subtraction data and ranked using both simple cuts on the detection parameters and a machine learning algorithm (Bloom et al. 2012PASP..124.1175B), and then visually confirmed by members of the PTF collaboration or, from mid-2010 onwards, via the citizen science project 'Galaxy Zoo: Supernova' (Smith et al., 2011MNRAS.412.1309S). The latter identified eight of the SNe studied in this paper. (4 data files).

  18. The host of the Type I SLSN 2017egm. A young, sub-solar metallicity environment in a massive spiral galaxy

    Science.gov (United States)

    Izzo, L.; Thöne, C. C.; García-Benito, R.; de Ugarte Postigo, A.; Cano, Z.; Kann, D. A.; Bensch, K.; Della Valle, M.; Galadí-Enríquez, D.; Hedrosa, R. P.

    2018-02-01

    Context. Type I superluminous supernova (SLSN) host galaxies are predominantly low-metallicity, highly star-forming (SF) dwarfs. One of the current key questions is whether Type I SLSNe can only occur in such environments and hosts. Aims: Here we present an integral-field study of the massive, high-metallicity spiral NGC 3191, the host of SN 2017egm, the closest Type I SLSN known to date. We use data from PMAS/CAHA and the public MaNGA survey to shed light on the properties of the SLSN site and the origin of star formation in this non-starburst spiral galaxy. Methods: We map the physical properties of different H II regions throughout the galaxy and characterise their stellar populations using the STARLIGHT fitting code. Kinematical information allows us to study a possible interaction with its neighbouring galaxy as the origin of recent star formation activity which could have caused the SLSN. Results: NGC 3191 shows intense star formation in the western part with three large SF regions of low metallicity. Taking only the properties of emitting gas, the central regions of the host have a higher metallicity, a lower specific star formation rate, and lower ionisation. Modelling the stellar populations gives a different picture: the SLSN region has two dominant stellar populations with different ages, the younger one with an age of 2-10 Myr and lower metallicity, likely the population from which the SN progenitor originated. Emission line kinematics of NGC 3191 show indications of interaction with its neighbour MCG+08-19-017 at 45 kpc, which might be responsible for the recent starburst. In fact, this galaxy pair has hosted a total of four SNe, 1988B (Type Ia), SN 2003ds (Type Ic in MCG+08-19-017), PTF10bgl (Type II), and 2017egm, underlying the enhanced SF in both galaxies due to interaction. Conclusions: Our study shows that care should be taken when interpreting global host and even gas properties without looking at the stellar population history of the region

  19. Multi-Wavelength Studies on H2O Maser Host Galaxies J. S. Zhang ...

    Indian Academy of Sciences (India)

    on two projects: X-ray data analysis of individual maser source using. X-ray penetrability to explore maser host obscured AGN; multi- wavelength statistical properties of the whole published H2O maser sam- ple. Here their nuclear radio properties were investigated in detail, based on their 6-cm and 20-cm radio observation ...

  20. Morphology of Seyfert Galaxies

    OpenAIRE

    Chen, Yen-Chen; Hwang, Chorng-Yuan

    2017-01-01

    We probed the relation between properties of Seyfert nuclei and morphology of their host galaxies. We selected Seyfert galaxies from the Sloan Digital Sky Survey with redshifts less 0.2 identified by the V\\'{e}ron Catalog (13th). We used the "{\\it{FracDev}}" parameter from SDSS galaxy fitting models to represent the bulge fractions of the Seyfert host galaxies. We found that the host galaxies of Seyfert 1 and Seyfert 2 are dominated by large bulge fractions, and Seyfert 2 galaxies are more li...

  1. Discovery of 21 New Changing-look AGNs: Study on Evolution of AGNs and AGN Host Galaxies

    Science.gov (United States)

    Yang, Qian; Wu, Xuebing; Fan, Xiaohui; Jiang, Linhua; McGreer, Ian; Shangguan, Jinyi; Yao, Su; Wang, Bingquan; Joshi, Ravi; Green, Richard F.; Wang, Feige; Feng, Xiaotong; Fu, Yuming; Yang, Jinyi; Liu, Yuanqi

    2018-01-01

    The rare case of changing-look (CL) AGNs, with the appearance or disappearance of broad Balmer emission lines within a few years, challenges our understanding of the AGN unified model. We present a sample of 21 new CL AGNs at 0.08 Fiber Spectroscopic Telescope (LAMOST) and SDSS, and from photometric variability and new spectroscopic observations. The estimated upper limits of transition timescale of the CL AGNs in this sample span from 0.9 to 13 years in rest-frame. The continuum flux in the optical and mid-infrared becomes brighter when the CL AGNs turn on, or vice versa. Variations of more than 0.2 mag in the mid-infrared W1 band, from the Wide-field Infrared Survey Explorer (WISE), were detected in 15 CL AGNs during the transition. The optical and mid-infrared variability is not consistent with the scenario of variable obscuration in 10 CL AGNs at higher than 3σ confidence level. We confirm a bluer-when-brighter trend in the optical. However, the mid-infrared colors W1‑W2 become redder when the objects become brighter in the W1 band, possibly due to a stronger hot dust contribution in the W2 band when the AGN activity becomes stronger. The physical mechanism of type transition is important for understanding the evolution of AGNs. The rare CL AGNs provide exceptional cases for the black hole and host stellar velocity dispersion relation studies at higher redshift. The faint state spectrum can be used to obtain the host stellar velocity dispersion without contamination from AGN component, and the bright state spectrum can be used to calculate the black hole mass with broad Balmer emission lines. The images at the non-AGN phase of CL AGNs are useful for studies of AGN host galaxies avoiding contamination from the luminous central engines.

  2. Black hole growth and starburst activity at z = 0.6-4 in the Chandra Deep Field South. Host galaxies properties of obscured AGN

    Science.gov (United States)

    Brusa, M.; Fiore, F.; Santini, P.; Grazian, A.; Comastri, A.; Zamorani, G.; Hasinger, G.; Merloni, A.; Civano, F.; Fontana, A.; Mainieri, V.

    2009-12-01

    Aims: The co-evolution of host galaxies and the active black holes which reside in their centre is one of the most important topics in modern observational cosmology. Here we present a study of the properties of obscured active galactic nuclei (AGN) detected in the CDFS 1 Ms observation and their host galaxies. Methods: We limited the analysis to the MUSIC area, for which deep K-band observations obtained with ISAAC@VLT are available, ensuring accurate identifications of the counterparts of the X-ray sources as well as reliable determination of photometric redshifts and galaxy parameters, such as stellar masses and star formation rates. In particular, we: 1) refined the X-ray/infrared/optical association of 179 sources in the MUSIC area detected in the Chandra observation; 2) studied the host galaxies observed and rest frame colors and properties. Results: We found that X-ray selected (LX ⪆ 1042 erg s-1) AGN show Spitzer colors consistent with both AGN and starburst dominated infrared continuum; the latter would not have been selected as AGN from infrared diagnostics. The host galaxies of X-ray selected obscured AGN are all massive (Mast > 1010 M_⊙) and, in 50% of the cases, are also actively forming stars (1/SSFR 1 and Mast > 3 × 1011 M_⊙, a fraction significantly higher than in the local Universe for AGN of similar luminosities. Tables [see full textsee full textsee full text] and [see full textsee full textsee full text] are only available in electronic form at http://www.aanda.org

  3. A Tidal Disruption Event in a Nearby Galaxy Hosting an Intermediate Mass Black Hole

    Science.gov (United States)

    Donato, D; Cenko, S. B.; Covino, S.; Troja, E.; Pursimo, T.; Cheung, C. C.; Fox, O.; Kutyrev, A.; Campana, S.; Fugazza, D.; hide

    2014-01-01

    We report the serendipitous discovery of a bright point source flare in the Abell cluster A1795 with archival EUVE and Chandra observations. Assuming the EUVE emission is associated with the Chandra source, the X-ray 0.5-7 kiloelectronvolt flux declined by a factor of approximately 2300 over a time span of 6 years, following a power-law decay with index approximately equal to 2.44 plus or minus 0.40. The Chandra data alone vary by a factor of approximately 20. The spectrum is well fit by a blackbody with a constant temperature of kiloteslas approximately equal to 0.09 kiloelectronvolts (approximately equal to 10 (sup 6) Kelvin). The flare is spatially coincident with the nuclear region of a faint, inactive galaxy with a photometric redshift consistent at the 1 sigma level with the cluster (redshift = 0.062476).We argue that these properties are indicative of a tidal disruption of a star by a black hole (BH) with log(M (sub BH) / M (sub 1 solar mass)) approximately equal to 5.5 plus or minus 0.5. If so, such a discovery indicates that tidal disruption flares may be used to probe BHs in the intermediate mass range, which are very difficult to study by other means.

  4. Host galaxy identification for binary black hole mergers with long baseline gravitational wave detectors

    Science.gov (United States)

    Howell, E. J.; Chan, M. L.; Chu, Q.; Jones, D. H.; Heng, I. S.; Lee, H.-M.; Blair, D.; Degallaix, J.; Regimbau, T.; Miao, H.; Zhao, C.; Hendry, M.; Coward, D.; Messenger, C.; Ju, L.; Zhu, Z.-H.

    2018-03-01

    The detection of black hole binary coalescence events by Advanced LIGO allows the science benefits of future detectors to be evaluated. In this paper, we report the science benefits of one or two 8 km arm length detectors based on the doubling of key parameters in an Advanced LIGO-type detector, combined with realizable enhancements. It is shown that the total detection rate for sources similar to those already detected would increase to ˜ 103-105 per year. Within 0.4 Gpc, we find that around 10 of these events would be localizable to within ˜10-1 deg2. This is sufficient to make unique associations or to rule out a direct association with the brightest galaxies in optical surveys (at r-band magnitudes of 17 or above) or for deeper limits (down to r-band magnitudes of 20) yield statistically significant associations. The combination of angular resolution and event rate would benefit precision testing of formation models, cosmic evolution, and cosmological studies.

  5. A Precise Distance to the Host Galaxy of the Binary Neutron Star Merger GW170817 Using Surface Brightness Fluctuations

    Science.gov (United States)

    Cantiello, Michele; Jensen, J. B.; Blakeslee, J. P.; Berger, E.; Levan, A. J.; Tanvir, N. R.; Raimondo, G.; Brocato, E.; Alexander, K. D.; Blanchard, P. K.; Branchesi, M.; Cano, Z.; Chornock, R.; Covino, S.; Cowperthwaite, P. S.; D’Avanzo, P.; Eftekhari, T.; Fong, W.; Fruchter, A. S.; Grado, A.; Hjorth, J.; Holz, D. E.; Lyman, J. D.; Mandel, I.; Margutti, R.; Nicholl, M.; Villar, V. A.; Williams, P. K. G.

    2018-02-01

    The joint detection of gravitational waves (GWs) and electromagnetic radiation from the binary neutron star (BNS) merger GW170817 has provided unprecedented insight into a wide range of physical processes: heavy element synthesis via the r-process; the production of relativistic ejecta; the equation of state of neutron stars and the nature of the merger remnant; the binary coalescence timescale; and a measurement of the Hubble constant via the “standard siren” technique. In detail, all of these results depend on the distance to the host galaxy of the merger event, NGC 4993. In this Letter we measure the surface brightness fluctuation (SBF) distance to NGC 4993 in the F110W and F160W passbands of the Wide Field Camera 3 Infrared Channel (WFC3/IR) on the Hubble Space Telescope (HST). For the preferred F110W passband we derive a distance modulus of (m-M) =33.05+/- 0.08+/- 0.10 mag, or a linear distance d = 40.7 ± 1.4 ± 1.9 Mpc (random and systematic errors, respectively); a virtually identical result is obtained from the F160W data. This is the most precise distance to NGC 4993 available to date. Combining our distance measurement with the corrected recession velocity of NGC 4993 implies a Hubble constant H 0 = 71.9 ± 7.1 km s‑1 Mpc‑1. A comparison of our result to the GW-inferred value of H 0 indicates a binary orbital inclination of i ≳ 137°. The SBF technique can be applied to early-type host galaxies of BNS mergers to ∼100 Mpc with HST and possibly as far as ∼300 Mpc with the James Webb Space Telescope, thereby helping to break the inherent distance-inclination degeneracy of the GW data at distances where many future BNS mergers are likely to be detected. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with Program #15329 (PI: E

  6. VizieR Online Data Catalog: AGN-Host Galaxy Connection (Povic+, 2012)

    Science.gov (United States)

    Povic, M.; Sanchez-Portal, M.; Perez Garcia, A. M.; Bongiovanni, A.; Cepa, J.; Huertas-Company, M.; Lara-Lopez, M. A.; Fernandez Lorenzo, M.; Ederoclite, A.; Alfaro, E.; Castaneda, H.; Gallego, J.; Gonzalez-Serrano, J. I.; Gonzalez, J. J.

    2012-02-01

    Table presents the X-ray properties of all 1121 objects, including fluxes in six selected energy bands, and public available optical data for X-ray counterparts. X-ray flux in X/O flux ratio is the sum of fluxes in (0.5-2keV) and (2-4.5keV) bands, while the optical flux corresponds to R band. The represented hardness ratio was set using the same X-ray bands. Photometric redshifts and K-corrections were measured using the photometric information in five optical (Furusawa et al., 2008, Cat. J/ApJS/176/1), three NIR (Hewett et al., 2006MNRAS.367..454H; Hodgkin et al., 2009MNRAS.394..675H), and four MIR IRAC (SWIRE survey) bands. Morphological classification was obtained using the galSVM code (Huertas-Company et al., 2008A&A...478..971H, 2009A&A...497..743H), one of the new methods useful especially when dealing with high-redshift sources and low-resolution data. With galSVM we obtained the mean surface brightness, asymmetry, concentration index, Gini, Smoothness, M20 moment of light, and two probabilities p1 and p2 that the galaxy belongs to early- (E, S0, S0/Sa) or late-type, respectively. Stellarity and elongation parameters were obtained with SExtractor. All objects with stellarity parameter greater or equal to 0.9 were considered as compact in this work. We included in our analysis for early-type objects only those sources with p1 probabilities greater or equal to 0.75, and for late-type objects all sources with probabilities p2 greater than 0.5. (1 data file).

  7. The Illustris simulation: supermassive black hole-galaxy connection beyond the bulge

    Science.gov (United States)

    Mutlu-Pakdil, Burçin; Seigar, Marc S.; Hewitt, Ian B.; Treuthardt, Patrick; Berrier, Joel C.; Koval, Lauren E.

    2018-02-01

    We study the spiral arm morphology of a sample of the local spiral galaxies in the Illustris simulation and explore the supermassive black hole-galaxy connection beyond the bulge (e.g. spiral arm pitch angle, total stellar mass, dark matter mass, and total halo mass), finding good agreement with other theoretical studies and observational constraints. It is important to study the properties of supermassive black holes and their host galaxies through both observations and simulations and compare their results in order to understand their physics and formative histories. We find that Illustris prediction for supermassive black hole mass relative to pitch angle is in rather good agreement with observations and that barred and non-barred galaxies follow similar scaling relations. Our work shows that Illustris presents very tight correlations between supermassive black hole mass and large-scale properties of the host galaxy, not only for early-type galaxies but also for low-mass, blue and star-forming galaxies. These tight relations beyond the bulge suggest that halo properties determine those of a disc galaxy and its supermassive black hole.

  8. SN 2010ay Is a Luminous and Broad-Lined Type Ic Supernova Within a Low-Metallicity Host Galaxy

    Science.gov (United States)

    Sanders, N. E.; Soderberg, A. M.; Valenti, S.; Foley, R. J.; Chornock, R.; Chomiuk, L.; Berger, E.; Smartt, S.; Hurley, K.; Barthelmy, S. D.; hide

    2012-01-01

    We report on our serendipitous pre-discovery detection and follow-up observations of the broad-lined Type Ic supernova (SN Ic) 2010ay at z = 0.067 imaged by the Pan-STARRS1 3pi survey just approximately 4 days after explosion. The supernova (SN) had a peak luminosity, MR approx. -20.2 mag, significantly more luminous than known GRB-SNe and one of the most luminous SNe Ib/c ever discovered. The absorption velocity of SN 2010ay is v Si (is) approx. 19×10(exp 3) km s-1 at approximately 40 days after explosion, 2-5 times higher than other broad-lined SNe and similar to the GRB-SN 2010bh at comparable epochs. Moreover, the velocity declines approximately 2 times slower than other SNe Ic-BL and GRB-SNe. Assuming that the optical emission is powered by radioactive decay, the peak magnitude implies the synthesis of an unusually large mass of 56Ni, MNi = 0.9 solar mass. Applying scaling relations to the light curve, we estimate a total ejecta mass, Mej (is) approx. 4.7 solar mass, and total kinetic energy, EK (is) approx. 11 × 10(exp 51) erg. The ratio of MNi to Mej is approximately 2 times as large for SN 2010ay as typical GRB-SNe and may suggest an additional energy reservoir. The metallicity (log(O/H)PP04 + 12 = 8.19) of the explosion site within the host galaxy places SN 2010ay in the low-metallicity regime populated by GRB-SNe, and (is) approximately 0.5(0.2) dex lower than that typically measured for the host environments of normal (broad-lined) SNe Ic. We constrain any gamma-ray emission with E(gamma) (is) approximately less than 6 × 10(exp 48) erg (25-150 keV), and our deep radio follow-up observations with the Expanded Very Large Array rule out relativistic ejecta with energy E (is) approximately greater than 10(exp 48) erg. We therefore rule out the association of a relativistic outflow like those that accompanied SN 1998bw and traditional long-duration gamma-ray bursts (GRBs), but we place less-stringent constraints on a weak afterglow like that seen from XRF

  9. Going the Distance: Mapping Host Galaxies of LIGO and VIRGO Sources in Three Dimensions using Local Cosmography and Targeted Follow-Up

    Science.gov (United States)

    Singer, Leo P.; Chen, Hsin-Yu; Holz, Daniel E.; Farr, Will M.; Price, Larry R.; Raymond, Vivien; Cenko, S. Bradley; Gehrels, Neil; Cannizzo, John K.; Kasliwal, Mansi M.; hide

    2016-01-01

    The Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) discovered gravitational waves (GWs) from a binary black hole merger in 2015 September and may soon observe signals from neutron star mergers. There is considerable interest in searching for their faint and rapidly fading electromagnetic (EM) counterparts, though GW position uncertainties are as coarse as hundreds of square degrees. Because LIGO's sensitivity to binary neutron stars is limited to the local universe, the area on the sky that must be searched could be reduced by weighting positions by mass, luminosity, or star formation in nearby galaxies. Since GW observations provide information about luminosity distance, combining the reconstructed volume with positions and redshifts of galaxies could reduce the area even more dramatically. A key missing ingredient has been a rapid GW parameter estimation algorithm that reconstructs the full distribution of sky location and distance. We demonstrate the first such algorithm, which takes under a minute, fast enough to enable immediate EM follow-up. By combining the three-dimensional posterior with a galaxy catalog, we can reduce the number of galaxies that could conceivably host the event by a factor of 1.4, the total exposure time for the Swift X-ray Telescope by a factor of 2, the total exposure time for a synoptic optical survey by a factor of 2, and the total exposure time for a narrow-field optical telescope by a factor of 3. This encourages us to suggest a new role for small field of view optical instruments in performing targeted searches of the most massive galaxies within the reconstructed volumes.

  10. GOING THE DISTANCE: MAPPING HOST GALAXIES OF LIGO AND VIRGO SOURCES IN THREE DIMENSIONS USING LOCAL COSMOGRAPHY AND TARGETED FOLLOW-UP

    International Nuclear Information System (INIS)

    Singer, Leo P.; Cenko, S. Bradley; Gehrels, Neil; Cannizzo, John; Chen, Hsin-Yu; Holz, Daniel E.; Farr, Ben; Farr, Will M.; Veitch, John; Berry, Christopher P. L.; Mandel, Ilya; Price, Larry R.; Raymond, Vivien; Kasliwal, Mansi M.; Nissanke, Samaya; Coughlin, Michael; Urban, Alex L.; Vitale, Salvatore; Mohapatra, Satya; Graff, Philip

    2016-01-01

    The Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) discovered gravitational waves (GWs) from a binary black hole merger in 2015 September and may soon observe signals from neutron star mergers. There is considerable interest in searching for their faint and rapidly fading electromagnetic (EM) counterparts, though GW position uncertainties are as coarse as hundreds of square degrees. Because LIGO’s sensitivity to binary neutron stars is limited to the local universe, the area on the sky that must be searched could be reduced by weighting positions by mass, luminosity, or star formation in nearby galaxies. Since GW observations provide information about luminosity distance, combining the reconstructed volume with positions and redshifts of galaxies could reduce the area even more dramatically. A key missing ingredient has been a rapid GW parameter estimation algorithm that reconstructs the full distribution of sky location and distance. We demonstrate the first such algorithm, which takes under a minute, fast enough to enable immediate EM follow-up. By combining the three-dimensional posterior with a galaxy catalog, we can reduce the number of galaxies that could conceivably host the event by a factor of 1.4, the total exposure time for the Swift X-ray Telescope by a factor of 2, the total exposure time for a synoptic optical survey by a factor of 2, and the total exposure time for a narrow-field optical telescope by a factor of 3. This encourages us to suggest a new role for small field of view optical instruments in performing targeted searches of the most massive galaxies within the reconstructed volumes.

  11. GOING THE DISTANCE: MAPPING HOST GALAXIES OF LIGO AND VIRGO SOURCES IN THREE DIMENSIONS USING LOCAL COSMOGRAPHY AND TARGETED FOLLOW-UP

    Energy Technology Data Exchange (ETDEWEB)

    Singer, Leo P.; Cenko, S. Bradley; Gehrels, Neil; Cannizzo, John [Astroparticle Physics Laboratory, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Chen, Hsin-Yu; Holz, Daniel E.; Farr, Ben [Department of Physics, Enrico Fermi Institute, and Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Farr, Will M.; Veitch, John; Berry, Christopher P. L.; Mandel, Ilya [School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT (United Kingdom); Price, Larry R.; Raymond, Vivien [LIGO Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States); Kasliwal, Mansi M. [Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Nissanke, Samaya [Institute of Mathematics, Astrophysics and Particle Physics, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Coughlin, Michael [Department of Physics and Astronomy, Harvard University, Cambridge, MA 02138 (United States); Urban, Alex L. [Leonard E. Parker Center for Gravitation, Cosmology, and Astrophysics, University of Wisconsin–Milwaukee, Milwaukee, WI 53201 (United States); Vitale, Salvatore; Mohapatra, Satya [LIGO Laboratory, Massachusetts Institute of Technology, 185 Albany Street, Cambridge, MA 02139 (United States); Graff, Philip [Department of Physics, University of Maryland, College Park, MD 20742 (United States)

    2016-09-20

    The Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) discovered gravitational waves (GWs) from a binary black hole merger in 2015 September and may soon observe signals from neutron star mergers. There is considerable interest in searching for their faint and rapidly fading electromagnetic (EM) counterparts, though GW position uncertainties are as coarse as hundreds of square degrees. Because LIGO’s sensitivity to binary neutron stars is limited to the local universe, the area on the sky that must be searched could be reduced by weighting positions by mass, luminosity, or star formation in nearby galaxies. Since GW observations provide information about luminosity distance, combining the reconstructed volume with positions and redshifts of galaxies could reduce the area even more dramatically. A key missing ingredient has been a rapid GW parameter estimation algorithm that reconstructs the full distribution of sky location and distance. We demonstrate the first such algorithm, which takes under a minute, fast enough to enable immediate EM follow-up. By combining the three-dimensional posterior with a galaxy catalog, we can reduce the number of galaxies that could conceivably host the event by a factor of 1.4, the total exposure time for the Swift X-ray Telescope by a factor of 2, the total exposure time for a synoptic optical survey by a factor of 2, and the total exposure time for a narrow-field optical telescope by a factor of 3. This encourages us to suggest a new role for small field of view optical instruments in performing targeted searches of the most massive galaxies within the reconstructed volumes.

  12. The role of bars in quenching star formation from z = 3 to the present epoch. Halpha3: an Halpha imaging survey of HI selected galaxies from ALFALFA, VI

    OpenAIRE

    Gavazzi, G.; Consolandi, G.; Dotti, M.; Fanali, R.; Fossati, M.; Fumagalli, M.; Viscardi, E.; Savorgnan, G.; Boselli, A.; Gutiérrez, L.; Toledo, H. Hernández; Giovanelli, R.; Haynes, M. P.

    2015-01-01

    A growing body of evidence indicates that the star formation rate per unit stellar mass (sSFR) decreases with increasing mass in normal main-sequence star-forming galaxies. Many processes have been advocated as being responsible for this trend (also known as mass quenching), e.g., feedback from active galactic nuclei (AGNs), and the formation of classical bulges. In order to improve our insight into the mechanisms regulating the star formation in normal star-forming galaxies across cosmic epo...

  13. SN 2010ay IS A LUMINOUS AND BROAD-LINED TYPE Ic SUPERNOVA WITHIN A LOW-METALLICITY HOST GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, N. E.; Soderberg, A. M.; Foley, R. J.; Chornock, R.; Chomiuk, L.; Berger, E. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Valenti, S.; Smartt, S.; Botticella, M. T. [Astrophysics Research Centre, School of Maths and Physics, Queen' s University, Belfast BT7 1NN (United Kingdom); Hurley, K. [Space Sciences Laboratory, University of California Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Barthelmy, S. D.; Gehrels, N.; Cline, T. [NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771 (United States); Levesque, E. M. [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Narayan, G. [Department of Physics, Harvard University, Cambridge, MA 02138 (United States); Briggs, M. S.; Connaughton, V. [CSPAR, University of Alabama in Huntsville, Huntsville, AL (United States); Terada, Y. [Department of Physics, Saitama University, Shimo-Okubo, Sakura-ku, Saitama-shi, Saitama 338-8570 (Japan); Golenetskii, S.; Mazets, E., E-mail: nsanders@cfa.harvard.edu [Ioffe Physico-Technical Institute, Laboratory for Experimental Astrophysics, 26 Polytekhnicheskaya, St. Petersburg 194021 (Russian Federation); and others

    2012-09-10

    We report on our serendipitous pre-discovery detection and follow-up observations of the broad-lined Type Ic supernova (SN Ic) 2010ay at z = 0.067 imaged by the Pan-STARRS1 3{pi} survey just {approx}4 days after explosion. The supernova (SN) had a peak luminosity, M{sub R} Almost-Equal-To -20.2 mag, significantly more luminous than known GRB-SNe and one of the most luminous SNe Ib/c ever discovered. The absorption velocity of SN 2010ay is v{sub Si} Almost-Equal-To 19 Multiplication-Sign 10{sup 3} km s{sup -1} at {approx}40 days after explosion, 2-5 times higher than other broad-lined SNe and similar to the GRB-SN 2010bh at comparable epochs. Moreover, the velocity declines {approx}2 times slower than other SNe Ic-BL and GRB-SNe. Assuming that the optical emission is powered by radioactive decay, the peak magnitude implies the synthesis of an unusually large mass of {sup 56}Ni, M{sub Ni} = 0.9 M{sub Sun }. Applying scaling relations to the light curve, we estimate a total ejecta mass, M{sub ej} Almost-Equal-To 4.7 M{sub Sun }, and total kinetic energy, E{sub K} Almost-Equal-To 11 Multiplication-Sign 10{sup 51} erg. The ratio of M{sub Ni} to M{sub ej} is {approx}2 times as large for SN 2010ay as typical GRB-SNe and may suggest an additional energy reservoir. The metallicity (log (O/H){sub PP04} + 12 = 8.19) of the explosion site within the host galaxy places SN 2010ay in the low-metallicity regime populated by GRB-SNe, and {approx}0.5(0.2) dex lower than that typically measured for the host environments of normal (broad-lined) SNe Ic. We constrain any gamma-ray emission with E{sub {gamma}} {approx}< 6 Multiplication-Sign 10{sup 48} erg (25-150 keV), and our deep radio follow-up observations with the Expanded Very Large Array rule out relativistic ejecta with energy E {approx}> 10{sup 48} erg. We therefore rule out the association of a relativistic outflow like those that accompanied SN 1998bw and traditional long-duration gamma-ray bursts (GRBs), but we place less

  14. Redshift determination of the BL Lac object 3C 66A by the detection of its host galaxy cluster at z = 0.340

    Science.gov (United States)

    Torres-Zafra, Juanita; Cellone, Sergio A.; Buzzoni, Alberto; Andruchow, Ileana; Portilla, José G.

    2018-03-01

    The BL Lac object 3C 66A is one of the most luminous extragalactic sources at TeV γ-rays (very high energy, i.e. E > 100 GeV). Since TeV γ-ray radiation is absorbed by the extragalactic background light (EBL), it is crucial to know the redshift of the source in order to reconstruct its original spectral energy distribution, as well as to constrain EBL models. However, the optical spectrum of this BL Lac is almost featureless, so a direct measurement of z is very difficult; in fact, the published redshift value for this source (z = 0.444) has been strongly questioned. Based on EBL absorption arguments, several constraints to its redshift, in the range 0.096 environment of 3C 66A, with the goal of finding the galaxy group hosting this blazar. This study was made using optical images of a 5.5 × 5.5 arcmin2 field centred on the blazar, and spectra of 24 sources obtained with Gemini/GMOS-N multi-object spectroscopy. We found spectroscopic evidence of two galaxy groups along the blazar's line of sight: one at z ≃ 0.020 and the second one at z ≃ 0.340. The first one is consistent with a known foreground structure, while the second group presented here has six spectroscopically confirmed members. Their location along a red sequence in the colour-magnitude diagram allows us to identify 34 additional candidate members of the more distant group. The blazar's spectrum shows broad absorption features that we identify as arising in the intergalactic medium, thus allowing us to tentatively set a redshift lower limit at z_3C66A ≳ 0.33. As a consequence, we propose that 3C 66A is hosted in a galaxy that belongs to a cluster at z = 0.340.

  15. A tight relation between the age distributions of stellar clusters and the properties of the interstellar medium in the host galaxy

    Science.gov (United States)

    Miholics, Meghan; Kruijssen, J. M. Diederik; Sills, Alison

    2017-09-01

    The age distributions of stellar cluster populations have long been proposed to probe the recent formation history of the host galaxy. However, progress is hampered by the limited understanding of cluster disruption by evaporation and tidal shocks. We study the age distributions of clusters in smoothed particle hydrodynamics simulations of isolated disc galaxies, which include a self-consistent, physical model for the formation and dynamical evolution of the cluster population and account for the variation of cluster disruption in time and space. We show that the downward slope of the cluster age distribution due to disruption cannot be reproduced with a single functional form, because the disruption rate exhibits systematic trends with cluster age (the 'cruel cradle effect'). This problem is resolved by using the median cluster age to trace cluster disruption. Across 120 independent galaxy snapshots and simulated cluster populations, we perform two-dimensional power-law fits of the median cluster age to various macroscopic physical quantities and find that it scales as t_med∝ Σ ^{-0.51± 0.03}σ _1D^{-0.85± 0.10}M_min^γ, for the gas surface density Σ, gas velocity dispersion σ1D, and minimum cluster mass Mmin. This scaling accurately describes observed cluster populations and indicates disruption by impulsive tidal shocks from the interstellar medium. The term M_min^γ provides a model-independent way to measure the mass dependence of the cluster disruption time γ. Finally, the ensemble-average cluster lifetime depends on the gas density less strongly than the instantaneous disruption time of single clusters. These results reflect the variation of cluster disruption in time and space. We provide quantitative ways of accounting for these physics in cluster population studies.

  16. ALMA INVESTIGATION OF VIBRATIONALLY EXCITED HCN/HCO{sup +}/HNC EMISSION LINES IN THE AGN-HOSTING ULTRALUMINOUS INFRARED GALAXY IRAS 20551−4250

    Energy Technology Data Exchange (ETDEWEB)

    Imanishi, Masatoshi [Subaru Telescope, 650 North A’ohoku Place, Hilo, HI 96720 (United States); Nakanishi, Kouichiro [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Izumi, Takuma, E-mail: masa.imanishi@nao.ac.jp [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

    2016-07-01

    We present the results of ALMA Cycle 2 observations of the ultraluminous infrared galaxy IRAS 20551−4250 at HCN/HCO{sup +}/HNC J = 3–2 lines at both vibrational ground ( v = 0) and vibrationally excited ( v {sub 2} = 1) levels. This galaxy contains a luminous buried active galactic nucleus (AGN), in addition to starburst activity, and our ALMA Cycle 0 data revealed a tentatively detected vibrationally excited HCN v {sub 2} = 1f J = 4–3 emission line. In our ALMA Cycle 2 data, the HCN/HCO{sup +}/HNC J = 3–2 emission lines at v = 0 are clearly detected. The HCN and HNC v {sub 2} = 1f J = 3–2 emission lines are also detected, but the HCO{sup +} v {sub 2} = 1f J = 3–2 emission line is not. Given the high energy level of v {sub 2} = 1 and the resulting difficulty of collisional excitation, we compared these results with those of the calculation of infrared radiative pumping, using the available infrared 5–35 μ m spectrum. We found that all of the observational results were reproduced if the HCN abundance was significantly higher than that of HCO{sup +} and HNC. The flux ratio and excitation temperature between v {sub 2} = 1f and v = 0, after correction for possible line opacity, suggests that infrared radiative pumping affects rotational ( J -level) excitation at v = 0 at least for HCN and HNC. The HCN-to-HCO{sup +} v = 0 flux ratio is higher than those of starburst-dominated regions, and will increase even more when the derived high HCN opacity is corrected. The enhanced HCN-to-HCO{sup +} flux ratio in this AGN-hosting galaxy can be explained by the high HCN-to-HCO{sup +} abundance ratio and sufficient HCN excitation at up to J = 4, rather than the significantly higher efficiency of infrared radiative pumping for HCN than HCO{sup +}.

  17. QUASARS PROBING QUASARS. VIII. THE PHYSICAL PROPERTIES OF THE COOL CIRCUMGALACTIC MEDIUM SURROUNDING z ∼ 2–3 MASSIVE GALAXIES HOSTING QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Marie Wingyee; Prochaska, J. Xavier [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Hennawi, Joseph F., E-mail: lwymarie@ucolick.org [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69115 Heidelberg (Germany)

    2016-10-01

    We characterize the physical properties of the cool T  ∼ 10{sup 4} K circumgalactic medium (CGM) surrounding z  ∼ 2–3 quasar host galaxies, which are predicted to evolve into present-day massive ellipticals. Using a statistical sample of 14 quasar pairs with projected separation <300 kpc and spectra of high dispersion and high signal-to-noise ratio, we find extreme kinematics with low metal ion lines typically spanning ≈500 km s{sup −1}, exceeding any previously studied galactic population. The CGM is significantly enriched, even beyond the virial radius, with a median metallicity [M/H] ≈ −0.6. The α /Fe abundance ratio is enhanced, suggesting that halo gas is primarily enriched by core-collapse supernovae. The projected cool gas mass within the virial radius is estimated to be 1.9 × 10{sup 11} M {sub ⊙} ( R {sub ⊥}/160 kpc){sup 2}, accounting for ≈1/3 of the baryonic budget of the galaxy halo. The ionization state of CGM gas increases with projected distance from the foreground quasars, contrary to expectation if the quasar dominates the ionizing radiation flux. However, we also found peculiarities not exhibited in the CGM of other galaxy populations. In one absorption system, we may be detecting unresolved fluorescent Ly α emission, and another system shows strong N v lines. Taken together, these anomalies suggest that transverse sightlines are—at least in some cases—possibly illuminated. We also discovered a peculiar case where detection of the C ii fine-structure line implies an electron density >100 cm{sup −3} and sub-parsec-scale gas clumps.

  18. Hubble's Menagerie of Galaxies

    Indian Academy of Sciences (India)

    Srimath

    and barred spirals, in a se- quence of gradually loos- ening of spiral arms and diminishing brightness of the central bulge. one cannot infer its true shape. A galaxy m ay look °at- tened by a di®erent degree if view ed from a di®erent d irectio n . Spiral galaxies are m arked by spiral `arm s' around a bright,nuclear region,often ...

  19. The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VII. Properties of the Host Galaxy and Constraints on the Merger Timescale

    Energy Technology Data Exchange (ETDEWEB)

    Blanchard, P. K.; Berger, E.; Fong, W.; Nicholl, M.; Leja, J.; Conroy, C.; Alexander, K. D.; Margutti, R.; Williams, P. K. G.; Doctor, Z.; Chornock, R.; Villar, V. A.; Cowperthwaite, P. S.; Annis, J.; Brout, D.; Brown, D. A.; Chen, H. -Y.; Eftekhari, T.; Frieman, J. A.; Holz, D. E.; Metzger, B. D.; Rest, A.; Sako, M.; Soares-Santos, M.

    2017-10-16

    We present the properties of NGC 4993, the host galaxy of GW170817, the first gravitational wave (GW) event from the merger of a binary neutron star (BNS) system and the first with an electromagnetic (EM) counterpart. We use both archival photometry and new optical/near-IR imaging and spectroscopy, together with stellar population synthesis models to infer the global properties of the host galaxy. We infer a star formation history peaked at $\\gtrsim 10$ Gyr ago, with subsequent exponential decline leading to a low current star formation rate of 0.01 M$_{\\odot}$ yr$^{-1}$, which we convert into a binary merger timescale probability distribution. We find a median merger timescale of $11.2^{+0.7}_{-1.4}$ Gyr, with a 90% confidence range of $6.8-13.6$ Gyr. This in turn indicates an initial binary separation of $\\approx 4.5$ R$_{\\odot}$, comparable to the inferred values for Galactic BNS systems. We also use new and archival $Hubble$ $Space$ $Telescope$ images to measure a projected offset of the optical counterpart of $2.1$ kpc (0.64$r_{e}$) from the center of NGC 4993 and to place a limit of $M_{r} \\gtrsim -7.2$ mag on any pre-existing emission, which rules out the brighter half of the globular cluster luminosity function. Finally, the age and offset of the system indicates it experienced a modest natal kick with an upper limit of $\\sim 200$ km s$^{-1}$. Future GW$-$EM observations of BNS mergers will enable measurement of their population delay time distribution, which will directly inform their viability as the dominant source of $r$-process enrichment in the Universe.

  20. Gravitational wave sources from Pop III stars are preferentially located within the cores of their host Galaxies

    Science.gov (United States)

    Pacucci, Fabio; Loeb, Abraham; Salvadori, Stefania

    2017-10-01

    The detection of gravitational waves (GWs) generated by merging black holes has recently opened up a new observational window into the Universe. The mass of the black holes in the first and third Laser Interferometer Gravitational Wave Observatory (LIGO) detections (36-29 M⊙ and 32-19 M⊙) suggests low-metallicity stars as their most likely progenitors. Based on high-resolution N-body simulations, coupled with state-of-the-art metal enrichment models, we find that the remnants of Pop III stars are preferentially located within the cores of galaxies. The probability of a GW signal to be generated by Pop III stars reaches ∼90 per cent at ∼0.5 kpc from the galaxy centre, compared to a benchmark value of ∼5 per cent outside the core. The predicted merger rates inside bulges is ∼60 × βIII Gpc-3 yr-1 (βIII is the Pop III binarity fraction). To match the 90 per cent credible range of LIGO merger rates, we obtain: 0.03 proof for the existence of Pop III stars.

  1. Polar ring galaxies in the Galaxy Zoo

    Science.gov (United States)

    Finkelman, Ido; Funes, José G.; Brosch, Noah

    2012-05-01

    We report observations of 16 candidate polar-ring galaxies (PRGs) identified by the Galaxy Zoo project in the Sloan Digital Sky Survey (SDSS) data base. Deep images of five galaxies are available in the SDSS Stripe82 data base, while to reach similar depth we observed the remaining galaxies with the 1.8-m Vatican Advanced Technology Telescope. We derive integrated magnitudes and u-r colours for the host and ring components and show continuum-subtracted Hα+[N II] images for seven objects. We present a basic morphological and environmental analysis of the galaxies and discuss their properties in comparison with other types of early-type galaxies. Follow-up photometric and spectroscopic observations will allow a kinematic confirmation of the nature of these systems and a more detailed analysis of their stellar populations.

  2. Exploring the Origin of Kinematically Irregular Galaxies with MaNGA

    Science.gov (United States)

    Stark, David Vincent; Bundy, Kevin; Westfall, Kyle; Bershady, Matthew; Cheung, Edmond; Soler, Juan; Brinchmann, Jarle; Abraham, Roberto; Bizyaev, Dmitry; Masters, Karen; Weijmans, Anne-Marie; Chen, Yanmei; Jin, Yifei; Drory, Niv; Lopes, Alexandre Roman; Law, David

    2018-01-01

    Deviations from normal rotation in galaxies may have a number of potential drivers, including tidal interactions, gas inflows/outflows, spiral structure, bar/oval distortions, or other internally generated instabilities. Thanks to new massive IFU surveys like MaNGA, we can now characterize the gas and stellar kinematics of thousands of galaxies in the local universe, enabling statistical analyses on the frequency of disturbed kinematics, their origin, and their impact on their host galaxies. We present a census of kinematics in MaNGA using a modified version of the Radon transform to map radial variations in kinematic position angles (PA). We discuss the frequency of kinematically irregular disks, and describe commonly observed patterns in radial PA profiles. In order to constrain the drivers of these kinematic signatures, we analyze how they correlate with galaxy mass, environment, star formation history, and gas-phase metallicity.

  3. Jets in Active Galaxies

    Indian Academy of Sciences (India)

    Jets in active galaxies are signatures of energy supply via collimatedbeams of plasma from the galactic nucleus to the extendedregions of emission. These jets, which occur acrossthe electromagnetic spectrum, are powered by supermassiveblack holes in the centres of the host galaxies. Jets are seenon the scale of parsecs ...

  4. A comprehensive study of the spatially-resolved SFR in nearby disk galaxies using CALIFA IF data

    Science.gov (United States)

    Catalán-Torrecilla, C.; Gil de Paz, A.; Castillo-Morales, A.; Méndez-Abreu, J.; Califa Team

    2017-03-01

    A detailed analysis of the Star Formation Rate (SFR) distribution in nearby galaxies is essential to understand the mechanisms that drive the formation and evolution of galaxies. Although measurements of the integrated SFR in galaxies as a whole are also required to fulfill this goal, we focus here on the relative contribution of the SFR in the different components that shape galaxies (bulges, bars and disks). With this aim in mind, we combine for the first time in a large sample of nearby galaxies from the CALIFA survey, 2D multicomponent photometric decomposition with Integral Field Spectroscopy (IFS) data to enable measurements of the SFR in the different galaxy components. We find that not only more massive galaxies are being quenched more efficiently but also more massive disks tend to exhibit lower SFRs for a fixed value of their disk stellar masses in the SFR-M_* plane. We show that type-2 AGN host galaxies are mostly found in galaxies with the higher values of their stellar masses and that they contribute to decrease the specific SFR for bulges and disks, being this effect more important for the case of the bulges.

  5. Hα Velocity Fields and Galaxy Interaction in the Quartet of Galaxies ...

    Indian Academy of Sciences (India)

    2015-10-07

    Oct 7, 2015 ... Abstract. The quartet of galaxies NGC 7769, 7770, 7771 and 7771A is a system of interacting galaxies. Close interaction between galaxies caused characteristic morphological features: tidal arms and bars, as well as an induced star formation. In this study, we performed the Fabry–Perot scanning ...

  6. Matching Supernovae to Galaxies

    Science.gov (United States)

    Kohler, Susanna

    2016-12-01

    One of the major challenges for modern supernova surveys is identifying the galaxy that hosted each explosion. Is there an accurate and efficient way to do this that avoids investing significant human resources?Why Identify Hosts?One problem in host galaxy identification. Here, the supernova lies between two galaxies but though the centroid of the galaxy on the right is closer in angular separation, this may be a distant background galaxy that is not actually near the supernova. [Gupta et al. 2016]Supernovae are a critical tool for making cosmological predictions that help us to understand our universe. But supernova cosmology relies on accurately identifying the properties of the supernovae including their redshifts. Since spectroscopic followup of supernova detections often isnt possible, we rely on observations of the supernova host galaxies to obtain redshifts.But how do we identify which galaxy hosted a supernova? This seems like a simple problem, but there are many complicating factors a seemingly nearby galaxy could be a distant background galaxy, for instance, or a supernovas host could be too faint to spot.The authors algorithm takes into account confusion, a measure of how likely the supernova is to be mismatched. In these illustrations of low (left) and high (right) confusion, the supernova is represented by a blue star, and the green circles represent possible host galaxies. [Gupta et al. 2016]Turning to AutomationBefore the era of large supernovae surveys, searching for host galaxies was done primarily by visual inspection. But current projects like the Dark Energy Surveys Supernova Program is finding supernovae by the thousands, and the upcoming Large Synoptic Survey Telescope will likely discover hundreds of thousands. Visual inspection will not be possible in the face of this volume of data so an accurate and efficient automated method is clearly needed!To this end, a team of scientists led by Ravi Gupta (Argonne National Laboratory) has recently

  7. BVRI SURFACE PHOTOMETRY OF ISOLATED GALAXY TRIPLETS

    International Nuclear Information System (INIS)

    Hernandez-Toledo, H. M.; Mendez-Hernandez, H.; Aceves, H.; OlguIn, L.

    2011-01-01

    Optical broadband BVRI observations of 54 galaxies selected from the Catalog of Isolated Triplets of Galaxies in the Northern Hemisphere have been carried out at San Pedro Martir National Observatory to evaluate their photometric and morphological properties. We complement our analysis with Two-Micron All Sky Survey (2MASS) and Sloan Digital Sky Survey (SDSS) images and look for signatures likely related to interactions/mergers. We report apparent/absolute BVRI magnitudes and colors for the 54 galaxies. The membership of these galaxies is re-evaluated by imposing a reasonable condition of concordant redshifts upon the original selection criteria, rendering a final sample of 34 galaxies in 13 triplets, 12 galaxies in close pairs, and 8 galaxy outliers. The triplets are spiral-dominated systems in different dynamical stages from loosely interacting to almost merged objects. The incidence fraction of features likely associated with interactions is ∼56%, similar to those found in northern and southern compact groups. The average fraction of bars is 35% with a mean value of maximum bar ellipticity ε max ∼ 0.4. Bars are hosted in the late-type triplet spirals, almost twice more than in early-type spirals. The global fraction of rings is 20%, all in the late-type components. The overdensity of triplets with respect to the background and their current dynamical status, as devised from our estimate of their dynamical parameters, namely the harmonic radius R H , velocity dispersion σ, dimensionless crossing time H 0 τ c , and virial mass M V , appear to be sufficient to favor galaxy transformations similar to those seen in dense groups and clusters. By contrast, the lower fraction of bonafide ellipticals and the relatively higher fraction of late-type spirals make these triplets essentially different from the Hickson Compact Groups and more representative of the field. A modest 1.6 enhancement factor in the optical luminosity of the late-type triplet components

  8. A high-angular resolution study of the nuclear regions of quasar host galaxies with the NaCo simultaneous differential imager

    Energy Technology Data Exchange (ETDEWEB)

    Scharwaechter, J; Ivanov, V D [European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19 (Chile); Zuther, J [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Tacconi-Garman, L E [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Muenchen (Germany); Kotilainen, J K; Reunanen, J [Tuorla Observatory, University of Turku, Vaeisaelaentie 20, FIN-21500 Piikkioe (Finland)], E-mail: jscharwa@eso.org

    2008-10-15

    A project aiming at the study of the emission line gas morphology in quasar host galaxies by means of adaptive-optics-assisted simultaneous narrow-band imaging of the line and continuum emission is presented. The project makes use of the NaCo Simultaneous Differential Imager (SDI) in an extragalactic experiment. The quasar targets are selected according to the availability of a neighbouring natural guide star for adaptive optics (AO) correction and according to a redshift criterion which places one of the emission lines of Pa{beta}, H{alpha}, or [O III] into one of the three SDI narrow-band filters in the near-infrared H-band. The first results for six targets from the Sloan Digital Sky Survey (SDSS) Quasar Catalogue at redshifts of about 0.2, 1.4, and 2.1 are summarized. The strongest line emission is detected for the H{alpha} candidate SDSS J125400.42+033726.5 at a redshift of 1.386. A double-structured continuum source is found in the central region of SDSS J114203.40+005135.8, which might be correlated with the major merger process suggested by the one-armed tidal tail in the large scale morphology.

  9. The clustering of Lyman α emitters at z ≈ 7: implications for reionization and host halo masses

    Science.gov (United States)

    Sobacchi, Emanuele; Mesinger, Andrei

    2015-10-01

    The Lyman α (Lyα) 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 Suprime-Cam (HSC), we study the angular correlation function (ACF) of narrow-band selected, z ≈ 7 Lyα emitting galaxies (LAEs). The clustering of LAEs is determined by both (i) their typical host halo masses, bar{M}_h, and (ii) the absorption due to a patchy EoR, characterized by an average neutral fraction of the intergalactic medium, bar{x}_{H I}. We bracket the allowed LAE ACFs by exploring extreme scenarios for both the intrinsic Lyα emission and the large-scale pattern (i.e. morphology) of cosmic ionized patches in physical EoR models. Independent of the EoR morphology, current z ≈ 7 ACF measurements constrain bar{x}_{H I}≲ 0.5 (1σ). We also find that the low values of the currently observed ACF imply that LAEs are hosted by relatively small dark matter haloes: bar{M}_h ≲ 10^{10} M_{⊙}, with corresponding duty cycles of ≲few per cent. These values are over an order of magnitude lower than the analogous ones for colour-selected, Lyman break galaxies, suggesting that z ≈ 7 narrow-band LAEs searches are preferentially selecting young, starburst galaxies, residing in less massive haloes. The upcoming Ultra Deep campaign with the HSC will significantly improve constraints on both the EoR and LAE host haloes.

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

    Science.gov (United States)

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

    2018-01-01

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

  11. Study of the stellar line-strength indices and kinematics along bars

    NARCIS (Netherlands)

    Perez, I.; Sanchez-Blazquez, P.; Zurita, A.

    Aims. This is the first paper of a series that aims to understand the formation and evolution of bars in early-type spirals and their influence in the evolution of the galaxy. Methods. Optical long-slit spectra along the bar major-axis of a sample of 20 galaxies are analyzed. Velocity and velocity

  12. Starbursts and IRAS galaxies

    International Nuclear Information System (INIS)

    Belfort, P.

    1987-01-01

    Several observational hints suggest that most of the IRAS galaxies are undergoing bursts of star formation. A simple photometric model of starburst galaxy was developed in order to check whether starburst events are really able to account for the far-infrared and optical properties of all the IRAS galaxies with HII region-like spectra. FIR activities up to a few hundred are actually easily reached with rather small bursts in red host-galaxies, and L IR /L B , EW(Hα) and U-B) versus (B-V) diagrams can be used to estimate burst strength and extinction. But more observations are required to conclude about the most extreme cases. Four typical infrared-selected IRAS galaxies are presented and their burst strength and extinction estimated

  13. Nuclear Activity of Compact Group Galaxies

    Science.gov (United States)

    Jubee, Sohn; Hwang, H.; Lee, M.; Lee, G.; Lee, J.

    2013-01-01

    We present results of a study on nuclear activities of compact group galaxies in the local universe. The triggering mechanism of AGN is an intriguing proble, and one of the suggested AGN triggering mechanism is galaxy interaction. In this regard, compact groups are a great laboratory to study the connection between galaxy interaction and nuclear activities. To study the environmental effects on nuclear activity, we estimate the fraction of AGN-host galaxies for a spectroscopic sample of 238 member galaxies in 59 compact groups from the Sloan Digital Sky Survey using the emission-line ratio diagnostic diagrams in comparison with field and cluster regions. We derive the 17-42% of AGN fraction of the compact groups depending on the AGN classification methods. The AGN fraction of compact groups is not the highest among the galaxy environments for both early and late type galaxies. We also examine the environmental dependence of nuclear activity using the surface galaxy number density. For early type galaxies, the AGN fraction decreases with increasing galaxy number density, while the AGN fraction of late-type galaxies barely changes. Moreover, we do not find any mid-infrared detected AGN-host compact group galaxies in our sample using WISE photometry. These results imply that the compact group galaxies is not stronngly active because of lack of gas supply, in contrast to the expectation that they may experience frequent galaxy-galaxy interactions.

  14. Internal and environmental secular evolution of disk galaxies

    Science.gov (United States)

    Kormendy, John

    2015-03-01

    that are available to them. They do this by spreading - the inner parts shrink while the outer parts expand. Significant changes happen only if some process efficiently transports energy or angular momentum outward. The consequences are very general: evolution by spreading happens in stars, star clusters, protostellar and protoplanetary disks, black hole accretion disks and galaxy disks. This meeting is about disk galaxies, so the evolution most often involves the redistribution of angular momentum. We now have a good heuristic understanding of how nonaxisymmetric structures rearrange disk gas into outer rings, inner rings and stuff dumped onto the center. Numerical simulations reproduce observed morphologies very well. Gas that is transported to small radii reaches high densities that are seen in CO observations. Star formation rates measured (e.g.) in the mid-infrared show that many barred and oval galaxies grow, on timescales of a few Gyr, dense central `pseudobulges' that are frequently mistaken for classical (elliptical-galaxy-like) bulges but that were grown slowly out of the disk (not made rapidly by major mergers). Our resulting picture of secular evolution accounts for the richness observed in morphological classification schemes such as those of de Vaucouleurs (1959) and Sandage (1961). State-of-the art morphology discussions include the de Vaucouleurs Atlas of Galaxies (Buta et al. 2007) and Buta (2012, 2013). Pseudobulges as disk-grown alternatives to merger-built classical bulges are important because they impact many aspects of our understanding of galaxy evolution. For example, they are observed to contain supermassive black holes (BHs), but they do not show the well known, tight correlations between BH mass and host properties (Kormendy et al. 2011). We can distinguish between classical and pseudo bulges because the latter retain a `memory' of their disky origin. That is, they have one or more characteristics of disks: (1) flatter shapes than those of

  15. Dwarf galaxy evolution within the environments of massive galaxies

    Science.gov (United States)

    Arraki, Kenza S.; Klypin, Anatoly A.; Ceverino, Daniel; Trujillo-Gomez, Sebastian; Primack, Joel R.

    2016-01-01

    Understanding galaxy evolution depends on connecting large-scale structure determined by the ΛCDM model with, at minimum, the small-scale physics of gas, star formation, and stellar feedback. Formation of galaxies within dark matter halos is sensitive to the physical phenomena occurring within and around the halo. This is especially true for dwarf galaxies, which have the smallest potential wells and are more susceptible to the effects of gas ionization and removal than larger galaxies. At dwarf galaxies scales comparisons of dark matter-only simulations with observations has unveiled various differences including the core-cusp, the missing satellites, and the too-big-to-fail problems. We have run a new suite of hydrodynamical simulations using the ART code to examine the evolution of dwarf galaxies in massive host environments. These are cosmological zoom-in simulations including deterministic star formation and stellar feedback in the form of supernovae feedback, stellar winds, radiation pressure, and photoionization pressure. We simulates galaxies with final halo masses on the order of 1012 M⊙ with high resolution, allowing us to examine the satellite dwarf galaxies and local isolated dwarf galaxies around each primary galaxy. We analyzed the abundance and structure of these dwarfs specifically the velocity function, their star formation rates, core creation and the circumgalactic medium. By reproducing observations of dwarf galaxies in simulations we show how including baryons in simulations relieves tensions seen in comparing dark matter only simulations with observations.

  16. A Subhalo-Galaxy Correspondence Model of Galaxy Biasing

    Science.gov (United States)

    Kim, Juhan; Park, Changbom; Choi, Yun-Young

    2008-08-01

    We propose a model for allocating galaxies in cosmological N-body simulations. We identify each subhalo with a galaxy and assign luminosity and morphological type, assuming that the galaxy luminosity is a monotonic function of the host subhalo mass. Morphology is assigned using two simple relations between the subhalo mass and galaxy luminosity for different galaxy types. The first uses a constant luminosity ratio between early-type (E/SO) and late-type (S/Irr) galaxies at a fixed subhalo mass. The other assumes that galaxies of different morphological types but equal luminosity have a constant ratio of subhalo mass. We made a series of comparisons of the properties of these mock galaxies with those of SDSS galaxies. The resulting mock galaxy sample is found to successfully reproduce the observed local number density distribution except in high-density regions. We study the luminosity function as a function of local density, and find that the observed luminosity functions in different local density environments are overall well reproduced by the mock galaxies. A discrepancy is found at the bright end of the luminosity function of early types in the underdense regions and at the faint end of both morphological types in very high density regions. A significant fraction of the observed early-type galaxies in voids seem to have undergone relatively recent star formation and become brighter. The lack of faint mock galaxies in dense regions may be due to the strong tidal force of the central halo, which destroys less massive satellite subhalos around the simulation. The mass-to-light ratio is found to depend on the local density in a way similar to that observed in the SDSS sample. We have found an impressive agreement between our mock galaxies and the SDSS galaxies in the dependence of central velocity dispersion on the local density and luminosity.

  17. Isolated galaxies

    International Nuclear Information System (INIS)

    Einasto, Maret

    1990-01-01

    To test for the possible presence of really isolated galaxies, which form a randomly distributed population in voids, we compare the distribution of most isolated galaxies in an observed sample with distributions of the same number of random points using the nearest neighbour test. The results show that the random population of really isolated galaxies does not exist - even the most isolated galaxies are connected with systems of galaxies, forming their outlying parts. (author)

  18. The imprints of bars on the vertical stellar population gradients of galactic bulges

    Science.gov (United States)

    Molaeinezhad, A.; Falcón-Barroso, J.; Martínez-Valpuesta, I.; Khosroshahi, H. G.; Vazdekis, A.; La Barbera, F.; Peletier, R. F.; Balcells, M.

    2017-05-01

    This is the second paper of a series aimed to study the stellar kinematics and population properties of bulges in highly inclined barred galaxies. In this work, we carry out a detailed analysis of the stellar age, metallicity and [Mg/Fe] of 28 highly inclined (I > 65°) disc galaxies, from S0 to S(B)c, observed with the SAURON integral-field spectrograph. The sample is divided into two clean samples of barred and unbarred galaxies, on the basis of the correlation between the stellar velocity and h3 profiles, as well as the level of cylindrical rotation within the bulge region. We find that while the mean stellar age, metallicity and [Mg/Fe] in the bulges of barred and unbarred galaxies are not statistically distinct, the [Mg/Fe] gradients along the minor axis (away from the disc) of barred galaxies are significantly different than those without bars. For barred galaxies, stars that are vertically further away from the mid-plane are in general more [Mg/Fe]-enhanced and thus the vertical gradients in [Mg/Fe] for barred galaxies are mostly positive, while for unbarred bulges the [Mg/Fe] profiles are typically negative or flat. This result, together with the old populations observed in the barred sample, indicates that bars are long-lasting structures, and therefore are not easily destroyed. The marked [Mg/Fe] differences with the bulges of unbarred galaxies indicate that different formation/evolution scenarios are required to explain their build-up, and emphasizes the role of bars in redistributing stellar material in the bulge-dominated regions.

  19. AGN feedback in galaxy formation

    CERN Document Server

    Antonuccio-Delogu, Vincenzo

    2010-01-01

    During the past decade, convincing evidence has been accumulated concerning the effect of active galactic nuclei (AGN) activity on the internal and external environment of their host galaxies. Featuring contributions from well-respected researchers in the field, and bringing together work by specialists in both galaxy formation and AGN, this volume addresses a number of key questions about AGN feedback in the context of galaxy formation. The topics covered include downsizing and star-formation time scales in massive elliptical galaxies, the connection between the epochs of supermassive black h

  20. Occurrence of LINER galaxies within the galaxy group environment

    Science.gov (United States)

    Coldwell, Georgina V.; Pereyra, Luis; Alonso, Sol; Donoso, Emilio; Duplancic, Fernanda

    2017-05-01

    We study the properties of a sample of 3967 low-ionization nuclear emission-line region (LINER) galaxies selected from SDSS-DR7, with respect to their proximity to galaxy groups. The host galaxies of LINERs have been analysed and compared with a well-defined control sample of 3841 non-LINER galaxies matched in redshift, luminosity, colour, morphology, age and stellar mass content. We find no difference between LINER and control galaxies in terms of the colour and age of stellar population as a function of the virial mass and distance to the geometric centre of the group. However, we find that LINERs are more likely to populate low-density environments in spite of their morphology, which is typical of high-density regions such as rich galaxy clusters. For rich (poor) galaxy groups, the occurrence of LINERs is approximately two times lower (higher) than the occurrence of matched, non-LINER galaxies. Moreover, LINER hosts do not seem to follow the expected morphology-density relation in groups of high virial mass. The high frequency of LINERs in low-density regions could be due to the combination of a sufficient gas reservoir to power the low-ionization emission and/or enhanced galaxy interaction rates benefiting the gas flow towards their central regions.

  1. Galaxy mergers

    International Nuclear Information System (INIS)

    Roos, N.

    1981-01-01

    This thesis contains a series of four papers dealing with the effects of interactions among galaxies during the epoch of cluster formation. Galaxy interactions are investigated and the results incorporated in numerical simulations of the formation of groups and clusters of galaxies. The role of galaxy interactions is analysed in the more general context of simulations of an expanding universe. The evolution of galaxies in rich clusters is discussed. The results of the investigations are presented and their relation to other work done in the field are briefly reviewed and an attempt is made to link galaxy mergers to the occurrence of activity in galactic nuclei. (Auth.)

  2. ORBITAL DEPENDENCE OF GALAXY PROPERTIES IN SATELLITE SYSTEMS OF GALAXIES

    International Nuclear Information System (INIS)

    Hwang, Ho Seong; Park, Changbom

    2010-01-01

    We study the dependence of satellite galaxy properties on the distance to the host galaxy and the orbital motion (prograde and retrograde orbits) using the Sloan Digital Sky Survey (SDSS) data. From SDSS Data Release 7, we find 3515 isolated satellite systems of galaxies at z -1 . It is found that the radial distribution of early-type satellites in prograde orbit is strongly concentrated toward the host while that of retrograde ones shows much less concentration. We also find the orbital speed of late-type satellites in prograde orbit increases as the projected distance to the host (R) decreases while the speed decreases for those in retrograde orbit. At R less than 0.1 times the host virial radius (R vir,host ), the orbital speed decreases in both prograde and retrograde orbit cases. Prograde satellites are on average fainter than retrograde satellites for both early and late morphological types. The u - r color becomes redder as R decreases for both prograde and retrograde orbit late-type satellites. The differences between prograde and retrograde orbit satellite galaxies may be attributed to their different origin or the different strength of physical processes that they have experienced through hydrodynamic interactions with their host galaxies.

  3. Detailed Quantitative Classifications of Galaxy Morphology

    Science.gov (United States)

    Nair, Preethi

    2018-01-01

    Understanding the physical processes responsible for the growth of galaxies is one of the key challenges in extragalactic astronomy. The assembly history of a galaxy is imprinted in a galaxy’s detailed morphology. The bulge-to-total ratio of galaxies, the presence or absence of bars, rings, spiral arms, tidal tails etc, all have implications for the past merger, star formation, and feedback history of a galaxy. However, current quantitative galaxy classification schemes are only useful for broad binning. They cannot classify or exploit the wide variety of galaxy structures seen in nature. Therefore, comparisons of observations with theoretical predictions of secular structure formation have only been conducted on small samples of visually classified galaxies. However large samples are needed to disentangle the complex physical processes of galaxy formation. With the advent of large surveys, like the Sloan Digital Sky Survey (SDSS) and the upcoming Large Synoptic Survey Telescope (LSST) and WFIRST, the problem of statistics will be resolved. However, the need for a robust quantitative classification scheme will still remain. Here I will present early results on promising machine learning algorithms that are providing detailed classifications, identifying bars, rings, multi-armed spiral galaxies, and Hubble type.

  4. Barred Owl [ds8

    Data.gov (United States)

    California Natural Resource Agency — These data define the current range of Barred and hybrid Barred/Spotted Owls in California. The current range includes the coastal mountains of northern California...

  5. Barred Owl [ds8

    Data.gov (United States)

    California Department of Resources — These data define the current range of Barred and hybrid Barred/Spotted Owls in California. The current range includes the coastal mountains of northern California...

  6. The life-time of galactic bars: central mass concentrations and gravity torques

    OpenAIRE

    Bournaud, F.; Combes, F.; Semelin, B.

    2005-01-01

    Bars in gas-rich spiral galaxies are short-lived. They drive gas inflows through their gravity torques, and at the same time self-regulate their strength. Their robustness has been subject of debate, since it was thought that only the resulting central mass concentrations (CMCs) were weakening bars, and only relatively rare massive CMCs were able to completely destroy them. Through numerical simulations including gas dynamics, we find that with the gas parameters of normal spiral galaxies, th...

  7. On Modified Bar recursion

    DEFF Research Database (Denmark)

    Oliva, Paulo Borges

    2002-01-01

    Modified bar recursion is a variant of Spector's bar recursion which can be used to give a realizability interpretation of the classical axiom of dependent choice. This realizability allows for the extraction of witnesses from proofs of forall-exists-formulas in classical analysis. In this talk I...... shall report on results regarding the relationship between modified and Spector's bar recursion. I shall also show that a seemingly weak form of modified bar recursion is as strong as "full" modified bar recursion in higher types....

  8. The HIX galaxy survey II: HI kinematics of HI eXtreme galaxies

    Science.gov (United States)

    Lutz, K. A.; Kilborn, V. A.; Koribalski, B. S.; Catinella, B.; Józsa, G. I. G.; Wong, O. I.; Stevens, A. R. H.; Obreschkow, D.; Dénes, H.

    2018-02-01

    By analysing a sample of galaxies selected from the HI Parkes All Sky Survey (HIPASS) to contain more than 2.5 times their expected HI content based on their optical properties, we investigate what drives these HI eXtreme (HIX) galaxies to be so HI-rich. We model the H I kinematics with the Tilted Ring Fitting Code TiRiFiC and compare the observed HIX galaxies to a control sample of galaxies from HIPASS as well as simulated galaxies built with the semi-analytic model DARK SAGE. We find that (1) H I discs in HIX galaxies are more likely to be warped and more likely to host H I arms and tails than in the control galaxies, (2) the average H I and average stellar column density of HIX galaxies is comparable to the control sample, (3) HIX galaxies have higher H I and baryonic specific angular momenta than control galaxies, (4) most HIX galaxies live in higher-spin haloes than most control galaxies. These results suggest that HIX galaxies are H I-rich because they can support more H I against gravitational instability due to their high specific angular momentum. The majority of the HIX galaxies inherits their high specific angular momentum from their halo. The H I content of HIX galaxies might be further increased by gas-rich minor mergers. This paper is based on data obtained with the Australia Telescope Compact Array (ATCA) through the large program C 2705.

  9. The Radius-Luminosity Relationship for Active Galactic Nuclei: The Effect of Host-Galaxy Starlight on Luminosity Measurements. II. The Full Sample of Reverberation-Mapped AGNs

    DEFF Research Database (Denmark)

    Bentz, Misty C.; Peterson, Bradley M.; Netzer, Hagai

    2009-01-01

    to ground-based spectroscopic luminosity measurements at 5100 Å. After correcting the luminosities of the AGNs for the contribution from starlight, we re-examine the Hß R BLR-L relationship. Our best fit for the relationship gives a power-law slope of 0.52 with a range of 0.45-0.59 allowed...... by the uncertainties. This is consistent with our previous findings, and thus still consistent with the naive assumption that all AGNs are simply luminosity-scaled versions of each other. We discuss various consistency checks relating to the galaxy modeling and starlight contributions, as well as possible systematic...

  10. Structure and dynamics of ringed galaxies

    International Nuclear Information System (INIS)

    Buta, R.J.

    1984-01-01

    In many spiral and SO galaxies, single or multiple ring structures are visible in the disk. These inner rings (r), outer rings (R), and nuclear rings (nr) were investigated by means of morphology, photometry, and spectroscopy in order to provide basic data on a long neglected phenomenon. The metric properties of each ring are investigated and found to correlate with the structure of the parent galaxy. When properly calibrated, inner rings in barred (SB) systems can be used as geometric extragalactic distance indicators to distances in excess of 100 Mpc. Other statistics are presented that confirm previous indications that the rings have preferred shapes, relative sizes, and orientations with respect to bars. A survey is made of the less homogeneous non-barred (SA) ringed systems, and the causes of the inhomogeneity are isolated. It is shown that rings can be identified in multiple-ring SA systems that are exactly analogous to those in barred spirals

  11. Galaxies and clusters of galaxies

    International Nuclear Information System (INIS)

    Salpeter, E.E.

    1982-01-01

    Stellar populations and massive halos, the properties of individual galaxies, and the clusters of galaxies are discussed. Baade's concept of the two stellar populations in our Galaxy had an important influence on the theories of stellar evolution. In Baade's day, there were two puzzling questions. Population II stars manage to form more rapidly than population I stars. Population II has lower rotational velocity than population I. This story is affected by the presence of an extended, massive halo which was not known in Baade's day. It is known from galaxy rotation curves that massive halos extend much further out. The most striking feature about the variation amongst galaxies is the separation between elliptical and spiral galaxies, with SO-galaxies occupying an intermediate position. The absolute luminosity L of a galaxy provides the second parameter in a two-dimensional classification scheme. In many ways, elliptical galaxies bear the same relationship to late-type spirals as does our stellar population II to population I. Most galaxies occur in some kind of groupings, ranging from a small group such as Local Group to a rich and dense cluster such as the Coma cluster. The formation of galaxies is connected with the formation of clusters. Various models are presented and discussed. (Kato, T.)

  12. Observing and Simulating Galaxy Evolution

    DEFF Research Database (Denmark)

    Olsen, Karen Pardos

    model for galaxy evolution should explain any observed connection between SFR and the amount and properties of the molecular gas of the interstellar medium (ISM). In proposed models of that kind, an active galactic nucleus (AGN) phase is often invoked as the cause for the decrease or cease of star...... formation. This thesis consists of models and observations of gas and AGNs in massive galaxies at z _ 2, and how they may affect the overall SFR and the subsequent evolutionary trajectory of massive galaxies to z = 0. For an improved understanding of how observed gas emission lines link to the underlying......, and sheds light on the AGN-host co-evolution by connecting the fraction and luminosity of AGNs with galaxy properties. By analyzing a large survey in X-ray, AGNs of high and low X-ray luminosity are extracted among massive galaxies at z _ 2 via AGN classification methods, and stacking techniques of non...

  13. Closing in on a Short-Hard Burst Progenitor: Constraints From Early-Time Optical Imaging and Spectroscopy of a Possible Host Galaxy of GRB 050509b

    Energy Technology Data Exchange (ETDEWEB)

    Bloom, Joshua S.; Prochaska, J.X.; Pooley, D.; Blake, C.W.; Foley, R.J.; Jha, S.; Ramirez-Ruiz, E.; Granot, J.; Filippenko, A.V.; Sigurdsson, S.; Barth, A.J.; Chen,; Cooper, M.C.; Falco, E.E.; Gal, R.R.; Gerke, B.F.; Gladders, M.D.; Greene, J.E.; Hennanwi, J.; Ho, L.C.; Hurley, K.; /UC, Berkeley, Astron. Dept. /Lick Observ.

    2005-06-07

    The localization of the short-duration, hard-spectrum gamma-ray burst GRB050509b by the Swift satellite was a watershed event. Never before had a member of this mysterious subclass of classic GRBs been rapidly and precisely positioned in a sky accessible to the bevy of ground-based follow-up facilities. Thanks to the nearly immediate relay of the GRB position by Swift, we began imaging the GRB field 8 minutes after the burst and have continued during the 8 days since. Though the Swift X-ray Telescope (XRT) discovered an X-ray afterglow of GRB050509b, the first ever of a short-hard burst, thus far no convincing optical/infrared candidate afterglow or supernova has been found for the object. We present a re-analysis of the XRT afterglow and find an absolute position of R.A. = 12h36m13.59s, Decl. = +28{sup o}59'04.9'' (J2000), with a 1{sigma} uncertainty of 3.68'' in R.A., 3.52'' in Decl.; this is about 4'' to the west of the XRT position reported previously. Close to this position is a bright elliptical galaxy with redshift z = 0.2248 {+-} 0.0002, about 1' from the center of a rich cluster of galaxies. This cluster has detectable diffuse emission, with a temperature of kT = 5.25{sub -1.68}{sup +3.36} keV. We also find several ({approx}11) much fainter galaxies consistent with the XRT position from deep Keck imaging and have obtained Gemini spectra of several of these sources. Nevertheless we argue, based on positional coincidences, that the GRB and the bright elliptical are likely to be physically related. We thus have discovered reasonable evidence that at least some short-duration, hard-spectra GRBs are at cosmological distances. We also explore the connection of the properties of the burst and the afterglow, finding that GRB050509b was underluminous in both of these relative to long-duration GRBs. However, we also demonstrate that the ratio of the blast-wave energy to the {gamma}-ray energy is consistent with that

  14. Growing Galaxies Gently

    Science.gov (United States)

    2010-10-01

    of the flow of pristine gas from the surrounding space and the associated formation of new stars. They were very careful to make sure that their specimen galaxies had not been disturbed by interactions with other galaxies. The selected galaxies were very regular, smoothly rotating discs, similar to the Milky Way, and they were seen about two billion years after the Big Bang (at a redshift of around three). In galaxies in the modern Universe the heavy elements [1] are more abundant close to the centre. But when Cresci's team mapped their selected distant galaxies with the SINFONI spectrograph on the VLT [2] they were excited to see that in all three cases there was a patch of the galaxy, close to the centre, with fewer heavy elements, but hosting vigorously forming stars, suggesting that the material to fuel the star formation was coming from the surrounding pristine gas that is low in heavy elements. This was the smoking gun that provided the best evidence yet of young galaxies accreting primitive gas and using it to form new generations of stars. As Cresci concludes: "This study has only been possible because of the outstanding performance of the SINFONI instrument on the VLT. It has opened a new window for studying the chemical properties of very distant galaxies. SINFONI provides information not only in two spatial dimensions, but also in a third, spectral dimension, which allows us to see the internal motions inside galaxies and study the chemical composition of the interstellar gas." Notes [1] The gas filling the early Universe was almost all hydrogen and helium. The first generations of stars processed this primitive material to create heavier elements such as oxygen, nitrogen and carbon by nuclear fusion. When this material was subsequently spewed back into space by intense particle winds from massive young stars and supernova explosions the amounts of heavy elements in the galaxy gradually increased. Astronomers refer to elements other than hydrogen and

  15. Hα Emission Line Morphologies in Markarian Starburst Galaxies A ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging Solutions)

    Hα imaging survey of a sample of neutral-gas rich S0 galaxies. ..... do not find a strong correlation between the global EW and the B − V colours of the .... colour maps. The line emission is along a bar misaligned with the optical contours of the galaxy (Chitre, Joshi & Ganesh 1999). The EW peaks 6 away from the optical.

  16. Bar and Theta Hyperoperations

    Directory of Open Access Journals (Sweden)

    Thomas Vougiouklis

    2011-12-01

    Full Text Available In questionnaires the replacement of the scale of Likert by a bar was suggested in 2008 by Vougiouklis & Vougiouklis. The use of the bar was rapidly accepted in social sciences. The bar is closely related with fuzzy theory and has several advantages during both the filling-in questionnaires and mainly in the research processing. In this paper we relate hyperstructure theory with questionnaires and we study the obtained hyperstructures which are used as an organising device of the problem.

  17. Stellar Bar Evolution in the Absence of Dark Matter Halo

    Science.gov (United States)

    Roshan, Mahmood

    2018-02-01

    We study the stellar bar growth in high-resolution numerical galaxy models with and without dark matter halos. In all models, the galactic disk is exponential, and the halos are rigid or live Plummer spheres. More specifically, when there is no dark matter halo, we modify the gravitational force between point particles. To do so, we use the weak field limit of an alternative theory of dark matter known as MOG in the literature. The galaxy model in MOG has the same initial conditions as galaxy models with a dark matter halo. On the other hand, the initial random velocities and Toomre’s local stability parameter are the same for all of the models. We show that the evolution and growth of the bar in MOG is substantially different from the standard cases including dark matter halo. More importantly, we find that the bar growth rate and its final magnitude are smaller in MOG. On the other hand, the maximum value of the bar in MOG is smaller than that in the Newtonian models. It is shown that although the live dark matter halo may support bar instability, MOG has stabilizing effects. Furthermore, we show that MOG supports fast pattern speeds, and unlike in the dark matter halo models, the pattern speed does not decrease with time. These differences, combined with the relevant observations, may help to distinguish between dark matter and modified gravity in galactic scales.

  18. Bar Code Labels

    Science.gov (United States)

    1988-01-01

    American Bar Codes, Inc. developed special bar code labels for inventory control of space shuttle parts and other space system components. ABC labels are made in a company-developed anodizing aluminum process and consecutively marketed with bar code symbology and human readable numbers. They offer extreme abrasion resistance and indefinite resistance to ultraviolet radiation, capable of withstanding 700 degree temperatures without deterioration and up to 1400 degrees with special designs. They offer high resistance to salt spray, cleaning fluids and mild acids. ABC is now producing these bar code labels commercially or industrial customers who also need labels to resist harsh environments.

  19. ON THE ORIGIN OF FANAROFF-RILEY CLASSIFICATION OF RADIO GALAXIES: DECELERATION OF SUPERSONIC RADIO LOBES

    International Nuclear Information System (INIS)

    Kawakatu, Nozomu; Kino, Motoki; Nagai, Hiroshi

    2009-01-01

    We argue that the origin of 'FRI/FRII dichotomy' - the division between Fanaroff-Riley class I (FRI) with subsonic lobes and class II (FRII) radio sources with supersonic lobes is sharp in the radio-optical luminosity plane (Owen-White diagram) - can be explained by the deceleration of advancing radio lobes. The deceleration is caused by the growth of the effective cross-sectional area of radio lobes. We derive the condition in which an initially supersonic lobe turns into a subsonic lobe, combining the ram pressure equilibrium between the hot spots and the ambient medium with the relation between 'the hot spot radius' and 'the linear size of radio sources' obtained from the radio observations. We find that the dividing line between the supersonic lobes and subsonic ones is determined by the ratio of the jet power L j to the number density of the ambient matter at the core radius of the host galaxy n-bar a . It is also found that the maximal ratio of (L j ,n-bar a ) exists and its value resides in (L j ,n-bar a ) max ∼10 44-47 er s -1 cm 3 , taking into account considerable uncertainties. This suggests that the maximal value (L j ,n-bar a ) max separates between FRIs and FRIIs.

  20. Globular star cluster systems around galaxies. II. The cases of spiral and dwarf galaxies

    International Nuclear Information System (INIS)

    Tadjibaev, I.U.; Nuritdinov, S.N.; Ganiev, J.M.

    2015-01-01

    Our compiled catalogue of globular cluster systems (GCS) which had studied in pervious part [1] is replenished now essentially as it are not sufficient the data to search for some empirical relationships between physical GCS parameters of the spiral and dwarf galaxies with a glance host galaxy characteristics. A number of empirical relationships for GCS of spiral and dwarf galaxies is first found. These results are differing essentially from analogous relationships for GCS of elliptical and lenticular galaxies which were found in [1]. It is also offered a possible new approach to the origin theory of the poor GCS which occupy a significant portion in our list of dwarf and spiral galaxies

  1. Black hole masses in active galaxies

    OpenAIRE

    Barth, Aaron J.

    2004-01-01

    This contribution reviews two topics of current interest in the study of black hole demographics in active galaxies: Can the stellar velocity dispersions of quasar host galaxies be measured? And can we constrain the black hole mass function below 10^6 M_⊙?

  2. Demise of faint satellites around isolated early-type galaxies

    Science.gov (United States)

    Park, Changbom; Hwang, Ho Seong; Park, Hyunbae; Lee, Jong Chul

    2018-02-01

    The hierarchical galaxy formation scenario in the Cold Dark Matter cosmology with a non-vanishing cosmological constant Λ and geometrically flat space (ΛCDM) has been very successful in explaining the large-scale distribution of galaxies. However, there have been claims that ΛCDM over-predicts the number of satellite galaxies associated with massive galaxies compared with observations—the missing satellite galaxy problem1-3. Isolated groups of galaxies hosted by passively evolving massive early-type galaxies are ideal laboratories for identifying the missing physics in the current theory4-11. Here, we report—based on a deep spectroscopic survey—that isolated massive and passive early-type galaxies without any signs of recent wet mergers or accretion episodes have almost no satellite galaxies fainter than the r-band absolute magnitude of about Mr = -14. If only early-type satellites are used, the cutoff is at the somewhat brighter magnitude of about Mr = -15. Such a cutoff has not been found in other nearby satellite galaxy systems hosted by late-type galaxies or those with merger features. Various physical properties of satellites depend strongly on the host-centric distance. Our observations indicate that the satellite galaxy luminosity function is largely determined by the interaction of satellites with the environment provided by their host.

  3. Merger origin of radio galaxies investigated with HI observations

    NARCIS (Netherlands)

    Emonts, BHC; Morganti, R; Oosterloo, TA; van der Hulst, JM; Tadhunter, CN; van Moorsel, G; Holt, J

    2006-01-01

    We present results of an H I study of a complete sample of nearby radio galaxies. Our goal is to investigate whether merger or interaction events could be at the origin of the radio-AGN activity. Around five of our radio galaxies, hosted mainly by early-type galaxies, we detect extended H I in

  4. Seyfert Galaxies: Radio Continuum Emission Properties and the ...

    Indian Academy of Sciences (India)

    1989), hosted in spiral or lenticular galaxies (Weed- man 1977). Seyfert galaxies are broadly classified into type 1 and type 2 depending on the presence and absence of broad permitted emission lines in their optical spec- tra, respectively. Unification scheme of Seyfert galaxies hypothesizes that Seyfert type 1s and type 2s ...

  5. Bar-tailed

    NARCIS (Netherlands)

    Duijns, S.; Hidayati, N.A.; Piersma, T.

    2013-01-01

    Capsule Across the European wintering range Bar-tailed Godwits Limosa lapponica lapponica selected polychaete worms and especially Ragworms Hediste diversicolor, with differences between areas due to variations in prey availability.Aims To determine the diet of Bar-tailed Godwits across their

  6. The role of black holes in galaxy formation and evolution.

    Science.gov (United States)

    Cattaneo, A; Faber, S M; Binney, J; Dekel, A; Kormendy, J; Mushotzky, R; Babul, A; Best, P N; Brüggen, M; Fabian, A C; Frenk, C S; Khalatyan, A; Netzer, H; Mahdavi, A; Silk, J; Steinmetz, M; Wisotzki, L

    2009-07-09

    Virtually all massive galaxies, including our own, host central black holes ranging in mass from millions to billions of solar masses. The growth of these black holes releases vast amounts of energy that powers quasars and other weaker active galactic nuclei. A tiny fraction of this energy, if absorbed by the host galaxy, could halt star formation by heating and ejecting ambient gas. A central question in galaxy evolution is the degree to which this process has caused the decline of star formation in large elliptical galaxies, which typically have little cold gas and few young stars, unlike spiral galaxies.

  7. External versus internal triggers of bar formation in cosmological zoom-in simulations

    Science.gov (United States)

    Zana, Tommaso; Dotti, Massimo; Capelo, Pedro R.; Bonoli, Silvia; Haardt, Francesco; Mayer, Lucio; Spinoso, Daniele

    2018-01-01

    The emergence of a large-scale stellar bar is one of the most striking features in disc galaxies. By means of state-of-the-art cosmological zoom-in simulations, we study the formation and evolution of bars in Milky Way-like galaxies in a fully cosmological context, including the physics of gas dissipation, star formation and supernova feedback. Our goal is to characterize the actual trigger of the non-axisymmetric perturbation that leads to the strong bar observable in the simulations at z = 0, discriminating between an internal/secular and an external/tidal origin. To this aim, we run a suite of cosmological zoom-in simulations altering the original history of galaxy-satellite interactions at a time when the main galaxy, though already bar-unstable, does not feature any non-axisymmetric structure yet. We find that the main effect of a late minor merger and of a close fly-by is to delay the time of bar formation and those two dynamical events are not directly responsible for the development of the bar and do not alter significantly its global properties (e.g. its final extension). We conclude that, once the disc has grown to a mass large enough to sustain global non-axisymmetric modes, then bar formation is inevitable.

  8. DISCOVERY OF A PSEUDOBULGE GALAXY LAUNCHING POWERFUL RELATIVISTIC JETS

    Energy Technology Data Exchange (ETDEWEB)

    Kotilainen, Jari K.; Olguín-Iglesias, Alejandro [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, FI-21500 Piikkiö (Finland); León-Tavares, Jonathan; Baes, Maarten [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281-S9, B-9000 Gent (Belgium); Anórve, Christopher [Facultad de Ciencias de la Tierra y del Espacio de la Universidad Autónoma de Sinaloa, Blvd. de la Americas y Av. Universitarios S/N, Ciudad Universitaria, C.P. 80010, Culiacán Sinaloa, México (Mexico); Chavushyan, Vahram; Carrasco, Luis, E-mail: jarkot@utu.fi [Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE), Apartado Postal 51 y 216, 72000 Puebla (Mexico)

    2016-12-01

    Supermassive black holes launching plasma jets at close to the speed of light, producing gamma-rays, have ubiquitously been found to be hosted by massive elliptical galaxies. Since elliptical galaxies are generally believed to be built through galaxy mergers, active galactic nuclei (AGN) launching relativistic jets are associated with the latest stages of galaxy evolution. We have discovered a pseudobulge morphology in the host galaxy of the gamma-ray AGN PKS 2004-447. This is the first gamma-ray emitter radio-loud AGN found to have been launched from a system where both the black hole and host galaxy have been actively growing via secular processes. This is evidence of an alternative black hole–galaxy co-evolutionary path to develop powerful relativistic jets, which is not merger driven.

  9. DISCOVERY OF A PSEUDOBULGE GALAXY LAUNCHING POWERFUL RELATIVISTIC JETS

    International Nuclear Information System (INIS)

    Kotilainen, Jari K.; Olguín-Iglesias, Alejandro; León-Tavares, Jonathan; Baes, Maarten; Anórve, Christopher; Chavushyan, Vahram; Carrasco, Luis

    2016-01-01

    Supermassive black holes launching plasma jets at close to the speed of light, producing gamma-rays, have ubiquitously been found to be hosted by massive elliptical galaxies. Since elliptical galaxies are generally believed to be built through galaxy mergers, active galactic nuclei (AGN) launching relativistic jets are associated with the latest stages of galaxy evolution. We have discovered a pseudobulge morphology in the host galaxy of the gamma-ray AGN PKS 2004-447. This is the first gamma-ray emitter radio-loud AGN found to have been launched from a system where both the black hole and host galaxy have been actively growing via secular processes. This is evidence of an alternative black hole–galaxy co-evolutionary path to develop powerful relativistic jets, which is not merger driven.

  10. Galaxy Zoo: quantifying morphological indicators of galaxy interaction

    Science.gov (United States)

    Casteels, Kevin. R. V.; Bamford, Steven P.; Skibba, Ramin A.; Masters, Karen L.; Lintott, Chris J.; Keel, William C.; Schawinski, Kevin; Nichol, Robert C.; Smith, Arfon M.

    2013-02-01

    We use Galaxy Zoo 2 visual classifications to study the morphological signatures of interaction between similar-mass galaxy pairs in the Sloan Digital Sky Survey. We find that many observable features correlate with projected pair separation - not only obvious indicators of merging, disturbance and tidal tails, but also more regular features, such as spiral arms and bars. These trends are robustly quantified, using a control sample to account for observational biases, producing measurements of the strength and separation scale of various morphological responses to pair interaction. For example, we find that the presence of spiral features is enhanced at scales ≲ 70 h- 170 kpc, probably due to both increased star formation and the formation of tidal tails. On the other hand, the likelihood of identifying a bar decreases significantly in pairs with separations ≲ 30 h- 170 kpc, suggesting that bars are suppressed by close interactions between galaxies of similar mass. We go on to show how morphological indicators of physical interactions provide a way of significantly refining standard estimates for the frequency of close pair interactions, based on velocity offset and projected separation. The presence of loosely wound spiral arms is found to be a particularly reliable signal of an interaction, for projected pair separations up to ˜100 h- 170 kpc. We use this indicator to demonstrate our method, constraining the fraction of low-redshift galaxies in truly interacting pairs, with M* > 109.5 M⊙ and mass ratio <4, to be between 0.4 and 2.7 per cent.

  11. Exotic open-flavor $bc\\bar{q}\\bar{q}$, $bc\\bar{s}\\bar{s}$ and $qc\\bar{q}\\bar{b}$, $sc\\bar{s}\\bar{b}$ tetraquark states

    OpenAIRE

    Chen, Wei; Steele, T. G.; Zhu, Shi-Lin

    2013-01-01

    We study the exotic $bc\\bar{q}\\bar{q}$, $bc\\bar{s}\\bar{s}$ and $qc\\bar{q}\\bar{b}$, $sc\\bar{s}\\bar{b}$ systems by constructing the corresponding tetraquark currents with $J^P=0^+$ and $1^+$. After investigating the two-point correlation functions and the spectral densities, we perform QCD sum rule analysis and extract the masses of these open-flavor tetraquark states. Our results indicate that the masses of both the scalar and axial vector tetraquark states are about $7.1-7.2$ GeV for the $bc\\...

  12. Hubble Space Telescope Observations of Extended [O III]λ 5007 Emission in Nearby QSO2s: New Constraints on AGN Host Galaxy Interaction

    Science.gov (United States)

    Fischer, Travis C.; Kraemer, S. B.; Schmitt, H. R.; Longo Micchi, L. F.; Crenshaw, D. M.; Revalski, M.; Vestergaard, M.; Elvis, M.; Gaskell, C. M.; Hamann, F.; Ho, L. C.; Hutchings, J.; Mushotzky, R.; Netzer, H.; Storchi-Bergmann, T.; Straughn, A.; Turner, T. J.; Ward, M. J.

    2018-04-01

    We present a Hubble Space Telescope survey of extended [O III] λ5007 emission for a sample of 12 nearby (z continuing to be kinematically influenced by the central active galactic nucleus (AGN) out to an average radius of ∼1130 pc. These findings question the effectiveness of AGNs being capable of clearing material from their host bulge in the nearby universe and suggest that disruption of gas by AGN activity may prevent star formation without requiring evacuation. Additionally, we find a dichotomy in our targets when comparing [O III] radial extent and nuclear FWHM, where QSO2s with compact [O III] morphologies typically possess broader nuclear emission lines.

  13. Globular Clusters - Guides to Galaxies

    CERN Document Server

    Richtler, Tom; Joint ESO-FONDAP Workshop on Globular Clusters

    2009-01-01

    The principal question of whether and how globular clusters can contribute to a better understanding of galaxy formation and evolution is perhaps the main driving force behind the overall endeavour of studying globular cluster systems. Naturally, this splits up into many individual problems. The objective of the Joint ESO-FONDAP Workshop on Globular Clusters - Guides to Galaxies was to bring together researchers, both observational and theoretical, to present and discuss the most recent results. Topics covered in these proceedings are: internal dynamics of globular clusters and interaction with host galaxies (tidal tails, evolution of cluster masses), accretion of globular clusters, detailed descriptions of nearby cluster systems, ultracompact dwarfs, formations of massive clusters in mergers and elsewhere, the ACS Virgo survey, galaxy formation and globular clusters, dynamics and kinematics of globular cluster systems and dark matter-related problems. With its wide coverage of the topic, this book constitute...

  14. GALAXY EVOLUTION. An over-massive black hole in a typical star-forming galaxy, 2 billion years after the Big Bang.

    Science.gov (United States)

    Trakhtenbrot, Benny; Urry, C Megan; Civano, Francesca; Rosario, David J; Elvis, Martin; Schawinski, Kevin; Suh, Hyewon; Bongiorno, Angela; Simmons, Brooke D

    2015-07-10

    Supermassive black holes (SMBHs) and their host galaxies are generally thought to coevolve, so that the SMBH achieves up to about 0.2 to 0.5% of the host galaxy mass in the present day. The radiation emitted from the growing SMBH is expected to affect star formation throughout the host galaxy. The relevance of this scenario at early cosmic epochs is not yet established. We present spectroscopic observations of a galaxy at redshift z = 3.328, which hosts an actively accreting, extremely massive BH, in its final stages of growth. The SMBH mass is roughly one-tenth the mass of the entire host galaxy, suggesting that it has grown much more efficiently than the host, contrary to models of synchronized coevolution. The host galaxy is forming stars at an intense rate, despite the presence of a SMBH-driven gas outflow. Copyright © 2015, American Association for the Advancement of Science.

  15. An Elegant Galaxy in an Unusual Light

    Science.gov (United States)

    2010-09-01

    A new image taken with the powerful HAWK-I camera on ESO's Very Large Telescope at Paranal Observatory in Chile shows the beautiful barred spiral galaxy NGC 1365 in infrared light. NGC 1365 is a member of the Fornax cluster of galaxies, and lies about 60 million light-years from Earth. NGC 1365 is one of the best known and most studied barred spiral galaxies and is sometimes nicknamed the Great Barred Spiral Galaxy because of its strikingly perfect form, with the straight bar and two very prominent outer spiral arms. Closer to the centre there is also a second spiral structure and the whole galaxy is laced with delicate dust lanes. This galaxy is an excellent laboratory for astronomers to study how spiral galaxies form and evolve. The new infrared images from HAWK-I are less affected by the dust that obscures parts of the galaxy than images in visible light (potw1037a) and they reveal very clearly the glow from vast numbers of stars in both the bar and the spiral arms. These data were acquired to help astronomers understand the complex flow of material within the galaxy and how it affects the reservoirs of gas from which new stars can form. The huge bar disturbs the shape of the gravitational field of the galaxy and this leads to regions where gas is compressed and star formation is triggered. Many huge young star clusters trace out the main spiral arms and each contains hundreds or thousands of bright young stars that are less than ten million years old. The galaxy is too remote for single stars to be seen in this image and most of the tiny clumps visible in the picture are really star clusters. Over the whole galaxy, stars are forming at a rate of about three times the mass of our Sun per year. While the bar of the galaxy consists mainly of older stars long past their prime, many new stars are born in stellar nurseries of gas and dust in the inner spiral close to the nucleus. The bar also funnels gas and dust gravitationally into the very centre of the galaxy

  16. Galaxy Formation

    CERN Document Server

    Longair, Malcolm S

    2008-01-01

    This second edition of Galaxy Formation is an up-to-date text on astrophysical cosmology, expounding the structure of the classical cosmological models from a contemporary viewpoint. This forms the background to a detailed study of the origin of structure and galaxies in the Universe. The derivations of many of the most important results are derived by simple physical arguments which illuminate the results of more advanced treatments. A very wide range of observational data is brought to bear upon these problems, including the most recent results from WMAP, the Hubble Space Telescope, galaxy surveys like the Sloan Digital Sky Survey and the 2dF Galaxy Redshift Survey, studies of Type 1a supernovae, and many other observations.

  17. El Molino Restaurante Bar

    OpenAIRE

    Munera Alvarez, Nicolas; Borda Melguizo, Sebastian

    2012-01-01

    El restaurante El Molino será un nuevo concepto de restaurante bar ubicado en la Calera, enfocado en contemplar todos los factores de entretenimiento y alimentación que una persona puede esperar en la zona.

  18. The effects of assembly bias on the inference of matter clustering from galaxy-galaxy lensing and galaxy clustering

    Science.gov (United States)

    McEwen, Joseph E.; Weinberg, David H.

    2018-04-01

    The combination of galaxy-galaxy lensing (GGL) and galaxy clustering is a promising route to measuring the amplitude of matter clustering and testing modified gravity theories of cosmic acceleration. Halo occupation distribution (HOD) modeling can extend the approach down to nonlinear scales, but galaxy assembly bias could introduce systematic errors by causing the HOD to vary with large scale environment at fixed halo mass. We investigate this problem using the mock galaxy catalogs created by Hearin & Watson (2013, HW13), which exhibit significant assembly bias because galaxy luminosity is tied to halo peak circular velocity and galaxy colour is tied to halo formation time. The preferential placement of galaxies (especially red galaxies) in older halos affects the cutoff of the mean occupation function for central galaxies, with halos in overdense regions more likely to host galaxies. The effect of assembly bias on the satellite galaxy HOD is minimal. We introduce an extended, environment dependent HOD (EDHOD) prescription to describe these results and fit galaxy correlation measurements. Crucially, we find that the galaxy-matter cross-correlation coefficient, rgm(r) ≡ ξgm(r) . [ξmm(r)ξgg(r)]-1/2, is insensitive to assembly bias on scales r ≳ 1 h^{-1} Mpc, even though ξgm(r) and ξgg(r) are both affected individually. We can therefore recover the correct ξmm(r) from the HW13 galaxy-galaxy and galaxy-matter correlations using either a standard HOD or EDHOD fitting method. For Mr ≤ -19 or Mr ≤ -20 samples the recovery of ξmm(r) is accurate to 2% or better. For a sample of red Mr ≤ -20 galaxies we achieve 2% recovery at r ≳ 2 h^{-1} Mpc with EDHOD modeling but lower accuracy at smaller scales or with a standard HOD fit. Most of our mock galaxy samples are consistent with rgm = 1 down to r = 1h-1Mpc, to within the uncertainties set by our finite simulation volume.

  19. Star formation suppression in compact group galaxies

    DEFF Research Database (Denmark)

    Alatalo, K.; Appleton, P. N.; Lisenfeld, U.

    2015-01-01

    We present CO(1-0) maps of 12 warm H-2-selected Hickson Compact Groups (HCGs), covering 14 individually imaged warm H2 bright galaxies, with the Combined Array for Research in Millimeter Astronomy. We found a variety of molecular gas distributions within the HCGs, including regularly rotating disks......, bars, rings, tidal tails, and possibly nuclear outflows, though the molecular gas morphologies are more consistent with spirals and earlytype galaxies than mergers and interacting systems. Our CO-imaged HCG galaxies, when plotted on the Kennicutt-Schmidt relation, shows star formation (SF) suppression......-to-dust ratios of these galaxies to determine if an incorrect LCO-M(H2) conversion caused the apparent suppression and find that HCGs have normal gas-to-dust ratios. It is likely that the cause of the apparent suppression in these objects is associated with shocks injecting turbulence into the molecular gas...

  20. 0351+026: a QSO spawned by interacting galaxies

    International Nuclear Information System (INIS)

    Bothun, G.D.; Mould, J.; Heckman, T.; Balick, B.; Schommer, R.A.; Kristian, J.

    1982-01-01

    We present the results of a detailed investigation into the nature of the H I-rich quasi-stellar object 0351+026. An improved H I profile reveals the presence of two distinct components. A high-quality CCD image clearly shows the presence of two galaxies. The brighter galaxy hosts the QSO while the less luminous companion has a prominent, apparently stellar nucleus. Moreover, this image also shows streamers of nebulosity emanating from the two galaxies and has an overall morphology which is highly reminiscent of that seen in other strongly interacting galaxies. Optical spectroscopy of the system shows that [O III] emission lies between the two nuclei and there is strong evidence of stellar absorption lines in both the host and companion galaxies. Overall, our data suggest that this system represents a violent encounter between two low-luminosity H I-rich galaxies. The possibility exists that this collision has triggered the QSO activity in the brighter galaxy

  1. AGN feedback in dwarf galaxies?

    Science.gov (United States)

    Dashyan, Gohar; Silk, Joseph; Mamon, Gary A.; Dubois, Yohan; Hartwig, Tilman

    2018-02-01

    Dwarf galaxy anomalies, such as their abundance and cusp-core problems, remain a prime challenge in our understanding of galaxy formation. The inclusion of baryonic physics could potentially solve these issues, but the efficiency of stellar feedback is still controversial. We analytically explore the possibility of feedback from active galactic nuclei (AGNs) in dwarf galaxies and compare AGN and supernova (SN) feedback. We assume the presence of an intermediate-mass black hole within low-mass galaxies and standard scaling relations between the relevant physical quantities. We model the propagation and properties of the outflow and explore the critical condition for global gas ejection. Performing the same calculation for SNe, we compare the ability of AGNs and SNe to drive gas out of galaxies. We find that a critical halo mass exists below which AGN feedback can remove gas from the host halo and that the critical halo mass for an AGN is greater than the equivalent for SNe in a significant part of the parameter space, suggesting that an AGN could provide an alternative and more successful source of negative feedback than SNe, even in the most massive dwarf galaxies.

  2. The H IX galaxy survey - II. H I kinematics of H I eXtreme galaxies

    Science.gov (United States)

    Lutz, K. A.; Kilborn, V. A.; Koribalski, B. S.; Catinella, B.; Józsa, G. I. G.; Wong, O. I.; Stevens, A. R. H.; Obreschkow, D.; Dénes, H.

    2018-05-01

    By analysing a sample of galaxies selected from the H I Parkes All Sky Survey (HIPASS) to contain more than 2.5 times their expected H I content based on their optical properties, we investigate what drives these H I eXtreme (H IX) galaxies to be so H I-rich. We model the H I kinematics with the Tilted Ring Fitting Code TiRiFiC and compare the observed H IX galaxies to a control sample of galaxies from HIPASS as well as simulated galaxies built with the semi-analytic model DARK SAGE. We find that (1) H I discs in H IX galaxies are more likely to be warped and more likely to host H I arms and tails than in the control galaxies, (2) the average H I and average stellar column density of H IX galaxies is comparable to the control sample, (3) H IX galaxies have higher H I and baryonic specific angular momenta than control galaxies, (4) most H IX galaxies live in higher spin haloes than most control galaxies. These results suggest that H IX galaxies are H I-rich because they can support more H I against gravitational instability due to their high specific angular momentum. The majority of the H IX galaxies inherits their high specific angular momentum from their halo. The H I content of H IX galaxies might be further increased by gas-rich minor mergers. This paper is based on data obtained with the Australia Telescope Compact Array through the large program C 2705.

  3. Dual Active Galactic Nuclei in Nearby Galaxies

    Science.gov (United States)

    Das, Mousumi; Rubinur, Khatun; Karb, Preeti; Varghese, Ashlin; Novakkuni, Navyasree; James, Atul

    2018-04-01

    Galaxy mergers play a crucial role in the formation of massive galaxies and the buildup of their bulges. An important aspect of the merging process is the in-spiral of the supermassive black-holes (SMBHs) to the centre of the merger remnant and the eventual formation of a SMBH binary. If both the SMBHs are accreting they will form a dual or binary active galactic nucleus (DAGN). The final merger remnant is usually very bright and shows enhanced star formation. In this paper we summarise the current sample of DAGN from previous studies and describe methods that can be used to identify strong DAGN candidates from optical and spectroscopic surveys. These methods depend on the Doppler separation of the double peaked AGN emission lines, the nuclear velocity dispersion of the galaxies and their optical/UV colours. We describe two high resolution, radio observations of DAGN candidates that have been selected based on their double peaked optical emission lines (DPAGN). We also examine whether DAGN host galaxies have higher star formation rates (SFRs) compared to merging galaxies that do not appear to have DAGN. We find that the SFR is not higher for DAGN host galaxies. This suggests that the SFRs in DAGN host galaxies is due to the merging process itself and not related to the presence of two AGN in the system.

  4. LINER galaxy properties and the local environment

    Science.gov (United States)

    Coldwell, Georgina V.; Alonso, Sol; Duplancic, Fernanda; Mesa, Valeria

    2018-05-01

    We analyse the properties of a sample of 5560 low-ionization nuclear emission-line region (LINER) galaxies selected from SDSS-DR12 at low red shift, for a complete range of local density environments. The host LINER galaxies were studied and compared with a well-defined control sample of 5553 non-LINER galaxies matched in red shift, luminosity, morphology and local density. By studying the distributions of galaxy colours and the stellar age population, we find that LINERs are redder and older than the control sample over a wide range of densities. In addition, LINERs are older than the control sample, at a given galaxy colour, indicating that some external process could have accelerated the evolution of the stellar population. The analysis of the host properties shows that the control sample exhibits a strong relation between colours, ages and the local density, while more than 90 per cent of the LINERs are redder and older than the mean values, independently of the neighbourhood density. Furthermore, a detailed study in three local density ranges shows that, while control sample galaxies are redder and older as a function of stellar mass and density, LINER galaxies mismatch the known morphology-density relation of galaxies without low-ionization features. The results support the contribution of hot and old stars to the low-ionization emission although the contribution of nuclear activity is not discarded.

  5. The power-law dependence of the Lyapunov exponents on the central mass in galaxies

    Science.gov (United States)

    Delis, N.

    2013-09-01

    We propose a theoretical interpretation for the observed (in numerical simulations) relation L~m^p , where L is the mean Lyapunov characteristic exponent of the chaotic orbits in galaxies hosting central black holes, and m is the ratio of the mass of the black hole over the mass of the galaxy. We construct a simple analytical model showing that in every close encounter with the central mass, a star's orbit exhibits a locally positive `stretching number', i.e. local Lyapunov exponent. Also, by the geometrical properties of the orbits, we estimate the frequency of visits of a chaotic orbit inside the black hole's sphere of influence, as well as the mean Lyapunov number as a function of the energy of an orbit. Combining these estimates, we find a theoretical value of the exponent p=2/3-q, with q~0.1-0.2. This value is verified by detailed numerical experiments. Finally, we show the applicability of the L~m^p law also in the case of rotating barred galaxies.

  6. INSPIRALLING SUPERMASSIVE BLACK HOLES: A NEW SIGNPOST FOR GALAXY MERGERS

    International Nuclear Information System (INIS)

    Comerford, Julia M.; Gerke, Brian F.; Newman, Jeffrey A.; Davis, Marc; Yan, Renbin; Cooper, Michael C.; Coil, Alison L.; Faber, S. M.; Koo, David C.; Rosario, D. J.; Dutton, Aaron A.

    2009-01-01

    We present a new technique for observationally identifying galaxy mergers spectroscopically rather than through host galaxy imaging. Our technique exploits the dynamics of supermassive black holes (SMBHs) powering active galactic nuclei (AGNs) in merger-remnant galaxies. Because structure in the universe is built up through galaxy mergers and nearly all galaxies host a central SMBH, some galaxies should possess two SMBHs near their centers as the result of a recent merger. These SMBHs spiral to the center of the resultant merger-remnant galaxy, and one or both of the SMBHs may power AGNs. Using the DEEP2 Galaxy Redshift Survey, we have examined 1881 red galaxies, of which 91 exhibit [O III] and Hβ emission lines indicative of Seyfert 2 activity. Of these, 32 AGNs have [O III] emission-line redshifts significantly different from the redshifts of the host galaxies' stars, corresponding to velocity offsets of ∼50 km s -1 to ∼300 km s -1 . Two of these AGNs exhibit double-peaked [O III] emission lines, while the remaining 30 AGNs each exhibit a single set of velocity-offset [O III] emission lines. After exploring a variety of physical models for these velocity offsets, we argue that the most likely explanation is inspiralling SMBHs in merger-remnant galaxies. Based on this interpretation, we find that roughly half of the red galaxies hosting AGNs are also merger remnants, which implies that mergers may trigger AGN activity in red galaxies. The AGN velocity offsets we find imply a merger fraction of ∼30% and a merger rate of ∼3 mergers Gyr -1 for red galaxies at redshifts 0.34 < z < 0.82.

  7. S0 galaxies in Formax

    DEFF Research Database (Denmark)

    Bedregal...[], A. G.; Aragón-Salamanca, A.; Merrifield, M. R.

    2006-01-01

    Galaxies: elliptical and lenticular, cD: galaxies: kinematics and dynamics Udgivelsesdato: Oct.1......Galaxies: elliptical and lenticular, cD: galaxies: kinematics and dynamics Udgivelsesdato: Oct.1...

  8. Island universes structure and evolution of disk galaxies

    CERN Document Server

    DE JONG, R. S

    2007-01-01

    This book contains an up-to-date review of the structure and evolution of disk galaxies from both the observational and theoretical point of view. The book is the proceedings of the "Island Universes" conference held at the island of Terschelling, The Netherlands in July 2005, which attracted about 130 experts and students in the field. The conference was organized as a tribute to Dr. Piet C. van der Kruit for receiving the honorary Jacobus C. Kapteyn Professorship in Astronomy. The eight topical themes discussed at the meeting are reflected in these proceedings: 1) Properties of Stellar Disks, 2) Kinematics and Dynamics of Disk Galaxies, 3) Bars, Spiral Structure, and Secular Evolution in Disk Galaxies, 4) The Outskirts and Environment of Disk Galaxies, 5) Interstellar Matter, 6) (Evolution of) Star Formation in Galactic Disks, 7) Disk Galaxies through Cosmic Time, and 8) Formation Models of Disk Galaxies. These proceedings are concluded with a conference summary reflecting on the most significant recent pro...

  9. Mechanical properties of weightlifting bars.

    Science.gov (United States)

    Chiu, Loren Z F

    2010-09-01

    Weightlifting training and competition involves lifting a revolving shaft bar loaded with weights. The design of a bar and the location of the weights result in bar deformation during lifting tasks. Because there are many manufacturers of weightlifting bars, the actual deformation of a bar may vary, depending on the steel alloys used. A modified 4-point static bending test was used to assess deformation of 8 weightlifting bars and 1 general purpose weight training bar. The apparent stiffness of the bars was determined by plotting bending moment vs. bar deformation (the vertical height difference between the center vs. ends of the bar). All bars tested had an absence of hysteresis during cyclic loading and unloading in 50-kg increments (up to 220-kg total barbell weight), demonstrating pure elastic properties. At maximum loading, bar deformation was 4-5 cm. A large range existed for apparent stiffness. Based on apparent stiffness calculations, recommendations are made for which bars are suitable for weightlifting training and competition. The deformable nature of weightlifting and weight training bars should be considered before their use in exercise, sport, or research.

  10. KINEMATICS OF M51-TYPE INTERACTING GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Günthardt, G. I.; Agüero, M. P. [Observatorio Astronómico, Universidad Nacional de Córdoba, Laprida 854, 5000 Córdoba (Argentina); Díaz, R. J., E-mail: guillermo.gunthardt@unc.edu.ar, E-mail: mpaguero@oac.uncor.edu, E-mail: rdiaz@gemini.edu [Gemini Observatory, AURA (United States)

    2016-11-01

    We present a kinematic catalog for 21 M51-type galaxies. It consists of radial velocity distributions observed with long-slit spectroscopy along different position angles, for both the main and satellite components. We detect deviations from circular motion in most of the main galaxies of each pair, due to the gravitational perturbation produced by the satellite galaxy. However, some systems do not show significant distortions in their radial velocity curves. We found some differences between the directions of the photometric and kinematic major axes in the main galaxies with a bar subsystem. The Tully–Fisher relation in the B -band and Ks -band for the present sample of M51-type systems is flatter than in isolated galaxies. Using the radial velocity data set, we built a synthetic normalized radial velocity distribution, as a reference for future modeling of these peculiar systems. The synthetic rotation curve, representing the typical rotation curve of the main galaxy in an M51-type pair, is near to solid body-like inside 4 kpc, and then is nearly flat within the radial range 5–15 kpc. The relative position angles between the major axis of the main galaxy and the companion’s location, as well as the amplitude of the velocity difference, indicate that the orbital motion of the satellite has a large projection on the equatorial plane of the main galaxy. In addition, the differences in radial velocity between the two galaxies indicate that the satellite’s orbital motion is within the range of amplitudes of the rotation curve of the main galaxy, and all the M51-type systems studied here, except for one, are gravitationally bound.

  11. Galaxy evolution. Isolated compact elliptical galaxies: stellar systems that ran away.

    Science.gov (United States)

    Chilingarian, Igor; Zolotukhin, Ivan

    2015-04-24

    Compact elliptical galaxies form a rare class of stellar system (~30 presently known) characterized by high stellar densities and small sizes and often harboring metal-rich stars. They were thought to form through tidal stripping of massive progenitors, until two isolated objects were discovered where massive galaxies performing the stripping could not be identified. By mining astronomical survey data, we have now found 195 compact elliptical galaxies in all types of environment. They all share similar dynamical and stellar population properties. Dynamical analysis for nonisolated galaxies demonstrates the feasibility of their ejection from host clusters and groups by three-body encounters, which is in agreement with numerical simulations. Hence, isolated compact elliptical and isolated quiescent dwarf galaxies are tidally stripped systems that ran away from their hosts. Copyright © 2015, American Association for the Advancement of Science.

  12. Breaking through the Bar

    Science.gov (United States)

    Gray, Katti

    2011-01-01

    Howard University School of Law had a problem, and school officials knew it. Over a 20-year period, 40 percent of its graduates who took the Maryland bar exam failed it on their first try. During the next 24 months--the time frame required to determine its "eventual pass rate"--almost 90 percent of the students did pass. What they did…

  13. Raising the Bar (3)

    NARCIS (Netherlands)

    Elhorst, Paul; Abreu, M.; Amaral, P.; Bhattacharjee, A.; Corrado, L.; Fingleton, B.; Fuerst, F.; Garretsen, H.; Igliori, D.; Le Gallo, J.; McCann, P.; Monastiriotis, V.; Pryce, G.; Yu, J.

    This editorial summarizes and comments on the papers published in issue 11(3) so as to raise the bar in applied spatial economic research and highlight new trends. The first paper proposes spatial and a-spatial indicators to describe the networks of airline companies around the world. The second

  14. SECULAR DAMPING OF STELLAR BARS IN SPINNING DARK MATTER HALOS

    Energy Technology Data Exchange (ETDEWEB)

    Long, Stacy; Shlosman, Isaac [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States); Heller, Clayton [Department of Physics, Georgia Southern University, Statesboro, GA 30460 (United States)

    2014-03-01

    We demonstrate using numerical simulations of isolated galaxies that growth of stellar bars in spinning dark matter halos is heavily suppressed in the secular phase of evolution. In a representative set of models, we show that for values of the cosmological spin parameter λ ≳ 0.03, bar growth (in strength and size) becomes increasingly quenched. Furthermore, the slowdown of the bar pattern speed weakens considerably with increasing λ until it ceases completely. The terminal structure of the bars is affected as well, including extent and shape of their boxy/peanut bulges. The essence of this effect lies in the modified angular momentum exchange between the disk and the halo facilitated by the bar. For the first time we have demonstrated that a dark matter halo can emit and not purely absorb angular momentum. Although the halo as a whole is not found to emit, the net transfer of angular momentum from the disk to the halo is significantly reduced or completely eliminated. The paradigm shift implies that the accepted view that disks serve as sources of angular momentum and halos serve as sinks must be revised. Halos with λ ≳ 0.03 are expected to form a substantial fraction, based on the lognormal distribution of λ. The dependence of secular bar evolution on halo spin, therefore, implies profound corollaries for the cosmological evolution of galactic disks.

  15. N-body modeling of barlens galaxies: Boxy/Peanut/X observed at different viewing geometries

    Science.gov (United States)

    Salo, Heikki; Laurikainen, Eija

    2017-06-01

    We use stellar dynamical N-body simulations to explore barlens galaxies, i.e. galaxies with lens-like central structures embedded in their bars, with a size about one-half of the narrow bar component. Because of their roundish isophotes, barlenses are often confused with classical bulges. However, growing evidence indicates that barlenses form a part of the bar, corresponding to the face-on projection of the vertically extended Boxy/Peanut/X central structures seen in edge-on barred galaxies (see Laurikainen et al. 2014, 2016, Athanassoula et al. 2015). B/P/X/barlens structures appear mostly in galaxies with stellar masses above 1010 solar masses. It has been suggested by Bland-Hawthorn & Gerhard (2016) that in face-on view also our Milky Way is likely to be a barlens galaxy.Here we review the morphological appearance of B/P/X/barlens galaxies (aspect ratio, size compared to the narrow bar) as a function of viewing inclination, by comparing synthetic images from simulations with the 3.6 micron data from S4G (Spitzer Survey of Stellar Structure in Galaxies). We demonstrate how the X/barlens morphology depends on the central mass concentration in galaxies; the pure barlens morphology requires steep inner rotation curves, while for shallower slopes the central structure still resembles a barlens, but shows boxy isophotes or X-signature even at low inclinations. This simulated behavior is confirmed with S4G data (Salo & Laurikainen 2017). We also use broadband SDSS colors and CALIFA DR3 data from literature, to analyze the ages and metallicities of the barlens components with respect to the narrow bar and the centralpeak of the galaxies. Finally, kinematic maps of the simulated galaxies are presented, illustrating the expected signatures of barlens component on the H3 and H4 Hermite-moments.

  16. Massive relic galaxies prefer dense environments

    Science.gov (United States)

    Peralta de Arriba, Luis; Quilis, Vicent; Trujillo, Ignacio; Cebrián, María; Balcells, Marc

    2016-09-01

    We study the preferred environments of z ∼ 0 massive relic galaxies (M⋆ ≳ 1010 M⊙ galaxies with little or no growth from star formation or mergers since z ∼ 2). Significantly, we carry out our analysis on both a large cosmological simulation and an observed galaxy catalogue. Working on the Millennium I-WMAP7 simulation we show that the fraction of today massive objects which have grown less than 10 per cent in mass since z ∼ 2 is ∼0.04 per cent for the whole massive galaxy population with M⋆ ≳ 1010 M⊙. This fraction rises to ∼0.18 per cent in galaxy clusters, confirming that clusters help massive galaxies remain unaltered. Simulations also show that massive relic galaxies tend to be closer to cluster centres than other massive galaxies. Using the New York University Value-Added Galaxy Catalogue, and defining relics as M⋆ ≳ 1010 M⊙ early-type galaxies with colours compatible with single-stellar population ages older than 10 Gyr, and which occupy the bottom 5-percentile in the stellar mass-size distribution, we find 1.11 ± 0.05 per cent of relics among massive galaxies. This fraction rises to 2.4 ± 0.4 per cent in high-density environments. Our findings point in the same direction as the works by Poggianti et al. and Stringer et al. Our results may reflect the fact that the cores of the clusters are created very early on, hence the centres host the first cluster members. Near the centres, high-velocity dispersions and harassment help cluster core members avoid the growth of an accreted stellar envelope via mergers, while a hot intracluster medium prevents cold gas from reaching the galaxies, inhibiting star formation.

  17. Stellar streams and the galaxies they reside in

    Science.gov (United States)

    Pearson, Sarah

    2018-01-01

    As galaxies collide, as smaller galaxies are disrupted by larger galaxies, or as clusters of stars orbit a galaxy, a gravitational tidal interaction unfolds and the systems tear apart into distinct morphological and kinematic structures. In my thesis, I have exploited these structures to understand various components of galaxies, such as the baryon cycle in dwarf galaxy interactions (Pearson et al. 2016, Pearson et al. 2017b). In this talk, I will focus on my thesis work related to the stellar stream emerging from the old, globular cluster, Palomar 5 (Pal 5), orbiting our own Milky Way. As the stellar stream members were once closely tied together in energy and angular momentum space, we can use their distribution in phase space to trace back where they were once located and what affected them along their paths. In particular, I will show that the mere existence of Pal 5’s thin stream can rule out a moderately triaxial potential model of our Galaxy (Pearson et al. 2015) and that the debris of Pal 5-like streams will spread much further in space in a triaxial potential (a mechanism which I dubbed “stream fanning”) . Additionally, I will show that the Milky Way's Galactic bar, can punch holes in stellar streams and explain the recently discovered length asymmetry between Pal 5’s leading and trailing arm (Pearson et al. 2017a). These holes grow and have locations along stellar streams dependent on the Galactic bar orientation, mass and rotational speed, which provides an intriguing methodology for studying our own Milky Way’s Galactic bar in more detail. The fact that the bar can create under densities in stellar streams, further demonstrates that we should be careful when interpreting gaps in stellar streams as indirect evidence of the existence of dark matter subhalos in our Galaxy.

  18. Crashing galaxies, cosmic fireworks

    International Nuclear Information System (INIS)

    Keel, W.C.

    1989-01-01

    The study of binary systems is reviewed. The history of the study of interacting galaxies, the behavior of gas in binary systems, studies to identify the processes that occur when galaxies interact, and the relationship of Seyfert galaxies and quasars to binary systems are discussed. The development of an atlas of peculiar galaxies (Arp, 1966) and methods for modeling galaxy interactions are examined

  19. Bar codes for nuclear safeguards

    International Nuclear Information System (INIS)

    Keswani, A.N.; Bieber, A.M. Jr.

    1983-01-01

    Bar codes similar to those used in supermarkets can be used to reduce the effort and cost of collecting nuclear materials accountability data. A wide range of equipment is now commercially available for printing and reading bar-coded information. Several examples of each of the major types of commercially available equipment are given, and considerations are discussed both for planning systems using bar codes and for choosing suitable bar code equipment

  20. A CLASSICAL MORPHOLOGICAL ANALYSIS OF GALAXIES IN THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G)

    Energy Technology Data Exchange (ETDEWEB)

    Buta, Ronald J. [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487-0324 (United States); Sheth, Kartik; Muñoz-Mateos, Juan-Carlos; Kim, Taehyun [National Radio Astronomy Observatory/NAASC, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Athanassoula, E.; Bosma, A. [Aix Marseille Universite, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388, Marseille (France); Knapen, Johan H. [Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna (Spain); Laurikainen, Eija; Salo, Heikki; Laine, Jarkko; Comerón, Sébastien [Division of Astronomy, Department of Physical Sciences, University of Oulu, Oulu, FI-90014 (Finland); Elmegreen, Debra [Vassar College, Deparment of Physics and Astronomy, Poughkeepsie, NY 12604 (United States); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Zaritsky, Dennis; Hinz, Joannah L. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Courtois, Helene [Université Lyon 1, CNRS/IN2P3, Institut de Physique Nucléaire, Lyon (France); Regan, Michael W. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Gadotti, Dimitri A. [European Southern Observatory, Casilla 19001, Santiago 19 (Chile); Paz, Armando Gil de [Departmento de Astrofisica, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Menéndez-Delmestre, Karín [University of Rio de Janeiro, Observatorio de Valongo, Ladeira Pedro Antonio, 43, CEP 20080-090, Rio de Janeiro (Brazil); and others

    2015-04-15

    The Spitzer Survey of Stellar Structure in Galaxies (S{sup 4}G) is the largest available database of deep, homogeneous middle-infrared (mid-IR) images of galaxies of all types. The survey, which includes 2352 nearby galaxies, reveals galaxy morphology only minimally affected by interstellar extinction. This paper presents an atlas and classifications of S{sup 4}G galaxies in the Comprehensive de Vaucouleurs revised Hubble-Sandage (CVRHS) system. The CVRHS system follows the precepts of classical de Vaucouleurs morphology, modified to include recognition of other features such as inner, outer, and nuclear lenses, nuclear rings, bars, and disks, spheroidal galaxies, X patterns and box/peanut structures, OLR subclass outer rings and pseudorings, bar ansae and barlenses, parallel sequence late-types, thick disks, and embedded disks in 3D early-type systems. We show that our CVRHS classifications are internally consistent, and that nearly half of the S{sup 4}G sample consists of extreme late-type systems (mostly bulgeless, pure disk galaxies) in the range Scd-Im. The most common family classification for mid-IR types S0/a to Sc is SA while that for types Scd to Sm is SB. The bars in these two type domains are very different in mid-IR structure and morphology. This paper examines the bar, ring, and type classification fractions in the sample, and also includes several montages of images highlighting the various kinds of “stellar structures” seen in mid-IR galaxy morphology.

  1. Revealing the Heart of the Galaxy : The Milky Way and its Black Hole

    NARCIS (Netherlands)

    Sanders, Robert H.

    2014-01-01

    1. Introduction: the luminous pathway; 2. The discovery of the Milky Way Galaxy; 3. The new physics; 4. Parting the veil with radio astronomy; 5. The violent Universe; 6. New windows on the Galactic Center; 7. The Milky Way as a barred spiral galaxy; 8. The evolving view of active galactic nuclei;

  2. The SAMI Galaxy Survey: first 1000 galaxies

    Science.gov (United States)

    Allen, J. T.

    2015-02-01

    The Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey is an ongoing project to obtain integral field spectroscopic observations of ~3400 galaxies by mid-2016. Including the pilot survey, a total of ~1000 galaxies have been observed to date, making the SAMI Galaxy Survey the largest of its kind in existence. This unique dataset allows a wide range of investigations into different aspects of galaxy evolution. The first public data from the SAMI Galaxy Survey, consisting of 107 galaxies drawn from the full sample, has now been released. By giving early access to SAMI data for the entire research community, we aim to stimulate research across a broad range of topics in galaxy evolution. As the sample continues to grow, the survey will open up a new and unique parameter space for galaxy evolution studies.

  3. Winding sense of galaxies around the local supercluster

    International Nuclear Information System (INIS)

    Aryal, Binil

    2011-01-01

    We present an analysis of the winding sense (S and Z-shapes) of 1621 field galaxies that have radial velocity between 3000 km s -1 and 5000 km s -1 . The preferred alignments of S- and Z-shaped galaxies are studied using chi-square, autocorrelation and Fourier series tests. We classify all the galaxies into 32 subsamples and notice a good agreement between the position angle (PA) distribution of the S- and Z-shaped galaxies. The homogeneous distribution of the S- and Z-shaped galaxies is more noticeable for the late-type spirals (Sc, Scd, Sd and Sm) than for the early-types (Sa, Sab, Sb and Sbc). A significant dominance of S-mode galaxies is apparent in the barred spirals. A random alignment is evident in the PA-distribution of Z- and S-mode spirals. In addition, a homogeneous distribution of the S- and Z-shaped galaxies is found to be invariant under global expansion. The PA-distribution of the total S-mode galaxies is found to be random, whereas a preferred alignment is clear for all the Z-mode galaxies. It is found that the galactic planes of Z-mode galaxies tend to lie in the equatorial plane.

  4. The Hot ISM of Normal Galaxies

    Science.gov (United States)

    Fabbiano, Giuseppina

    1999-01-01

    X-ray observations of galaxies have shown the presence of hot ISM and gaseous halos. The most spectacular examples am in early-type galaxies (E and S0), and in galaxies hosting intense starforming regions. This talk will review the observational evidence and highlight the outstanding issues in our understanding of this gaseous component, with emphasis on our present understanding of the chemical composition of these hot halos. It will address how Chandra, XMM, and future X-ray missions can address these studies.

  5. Dark and luminous matter in the NGC 3992 group of galaxies - II. The dwarf companions UGC 6923, UGC 6940, UGC 6969, and the Tully-Fisher relation

    NARCIS (Netherlands)

    Bottema, R

    Detailed neutral hydrogen observations have been obtained of the large barred spiral galaxy NGC 3992 and its three small companion spiral galaxies, UGC 6923, UGC 6940, and UGC 6969. Contrary to the large galaxy, for the companions the Hi distribution ends quite abruptly at the optical edges.

  6. Cooling of rectangular bars

    International Nuclear Information System (INIS)

    Frainer, V.J.

    1979-01-01

    A solution of the time-transient Heat Transfer Differential Equation in rectangular coordinates is presented, leading to a model which describes the temperature drop with time in rectangular bars. It is similar to an other model for cilindrical bars which has been previously developed in the Laboratory of Mechanical Metallurgy of UFRGS. Following these models, a generalization has been made, which permits cooling time evaluation for all profiles. These results are compared with experimental laboratory data in the 1200 to 800 0 C range. Some other existing models were also studied which have the purpose of studing the same phenomenon. Their mathematical forms and their evaluated values are analyzed and compared with experimental ones. (Author) [pt

  7. The Possible Heavy Tetraquarks $qQ\\bar q \\bar Q$, $qq\\bar Q \\bar Q$ and $qQ\\bar Q \\bar Q$

    OpenAIRE

    Cui, Ying; Chen, Xiao-Lin; Deng, Wei-Zhen; Zhu, Shi-Lin

    2006-01-01

    Assuming X(3872) is a $qc \\bar q \\bar c$ tetraquark and using its mass as input, we perform a schematic study of the masses of possible heavy tetraquarks using the color-magnetic interaction with the flavor symmetry breaking corrections.

  8. Triply heavy tetraquark states with the $QQ\\bar{Q}\\bar{q}$ configuration

    OpenAIRE

    Chen, Kan; Liu, Xiang; Wu, Jing; Liu, Yan-Rui; Zhu, Shi-Lin

    2016-01-01

    In the framework of the color-magnetic interaction, we systematically investigate the mass splittings of the $QQ\\bar{Q}\\bar{q}$ tetraquark states and estimated their rough masses in this work. These systems include the explicitly exotic states $cc\\bar{b}\\bar{q}$ and $bb\\bar{c}\\bar{q}$ and the hidden exotic states $cc\\bar{c}\\bar{q}$, $cb\\bar{b}\\bar{q}$, $bc\\bar{c}\\bar{q}$, and $bb\\bar{b}\\bar{q}$. If a state around the estimated mass region could be observed, its nature as a genuine tetraquark ...

  9. Bar coded retroreflective target

    Science.gov (United States)

    Vann, Charles S.

    2000-01-01

    This small, inexpensive, non-contact laser sensor can detect the location of a retroreflective target in a relatively large volume and up to six degrees of position. The tracker's laser beam is formed into a plane of light which is swept across the space of interest. When the beam illuminates the retroreflector, some of the light returns to the tracker. The intensity, angle, and time of the return beam is measured to calculate the three dimensional location of the target. With three retroreflectors on the target, the locations of three points on the target are measured, enabling the calculation of all six degrees of target position. Until now, devices for three-dimensional tracking of objects in a large volume have been heavy, large, and very expensive. Because of the simplicity and unique characteristics of this tracker, it is capable of three-dimensional tracking of one to several objects in a large volume, yet it is compact, light-weight, and relatively inexpensive. Alternatively, a tracker produces a diverging laser beam which is directed towards a fixed position, and senses when a retroreflective target enters the fixed field of view. An optically bar coded target can be read by the tracker to provide information about the target. The target can be formed of a ball lens with a bar code on one end. As the target moves through the field, the ball lens causes the laser beam to scan across the bar code.

  10. Dwarf spheroidal galaxies: Keystones of galaxy evolution

    Science.gov (United States)

    Gallagher, John S., III; Wyse, Rosemary F. G.

    1994-01-01

    Dwarf spheroidal galaxies are the most insignificant extragalactic stellar systems in terms of their visibility, but potentially very significant in terms of their role in the formation and evolution of much more luminous galaxies. We discuss the present observational data and their implications for theories of the formation and evolution of both dwarf and giant galaxies. The putative dark-matter content of these low-surface-brightness systems is of particular interest, as is their chemical evolution. Surveys for new dwarf spheroidals hidden behind the stars of our Galaxy and those which are not bound to giant galaxies may give new clues as to the origins of this unique class of galaxy.

  11. Multiple mechanisms quench passive spiral galaxies

    Science.gov (United States)

    Fraser-McKelvie, Amelia; Brown, Michael J. I.; Pimbblet, Kevin; Dolley, Tim; Bonne, Nicolas J.

    2018-02-01

    We examine the properties of a sample of 35 nearby passive spiral galaxies in order to determine their dominant quenching mechanism(s). All five low-mass (M⋆ environments. We postulate that cluster-scale gas stripping and heating mechanisms operating only in rich clusters are required to quench low-mass passive spirals, and ram-pressure stripping and strangulation are obvious candidates. For higher mass passive spirals, while trends are present, the story is less clear. The passive spiral bar fraction is high: 74 ± 15 per cent, compared with 36 ± 5 per cent for a mass, redshift and T-type matched comparison sample of star-forming spiral galaxies. The high mass passive spirals occur mostly, but not exclusively, in groups, and can be central or satellite galaxies. The passive spiral group fraction of 74 ± 15 per cent is similar to that of the comparison sample of star-forming galaxies at 61 ± 7 per cent. We find evidence for both quenching via internal structure and environment in our passive spiral sample, though some galaxies have evidence of neither. From this, we conclude no one mechanism is responsible for quenching star formation in passive spiral galaxies - rather, a mixture of mechanisms is required to produce the passive spiral distribution we see today.

  12. On the dynamical basis of the classification of normal galaxies.

    Science.gov (United States)

    Haass, J; Bertin, G; Lin, C C

    1982-06-01

    Some realistic galaxy models have been found to support discrete unstable spiral modes. Here, through the study of the relevant physical mechanisms and an extensive numerical investigation of the properties of the dominant modes in a wide class of galactic equilibria, we show how spiral structures are excited with different morphological features, depending on the properties of the equilibrium model. We identify the basic dynamical parameters and mechanisms and compare the resulting morphology of spiral modes with the actual classification of galaxies. The present study suggests a dynamical basis for the transition among various types and subclasses of normal and barred spiral galaxies.

  13. Chemical evolution of galaxies

    International Nuclear Information System (INIS)

    Vigroux, Laurent

    1979-01-01

    This research thesis addresses theories on the chemical evolution of galaxies which aim at explaining abundances of different elements in galaxies, and more particularly aims at improving the model by modifying hypotheses. After a description of the simple model and of its uncertainties, the author shows how it is possible to understand the evolution of the main elements. Predictions obtained with this model are then compared with the present knowledge on galaxies by considering them according to an increasing complexity: Sun's neighbourhood, our galaxy, other spiral galaxies, elliptical galaxies, and finally galaxy clusters. A specific attention is given to irregular galaxies which are the simplest systems [fr

  14. Evolution of dwarf galaxy properties in local group environments

    Science.gov (United States)

    Arraki, Kenza Sigrid

    Understanding galaxy evolution depends on connecting large-scale structures determined by the ACDM model with, at minimum, the small-scale physics of gas, star formation, and stellar feedback. Formation of galaxies within dark matter halos is sensitive to the physical phenomena occurring within and around the halo. This is especially true for dwarf galaxies, which have smaller potential wells and are more susceptible to the effects of tidal stripping and gas ionization and removal than larger galaxies. At dwarf galaxies scales comparisons of dark matter-only simulations with observations has unveiled various differences such as the core-cusp, the missing satellites, and the too big to fail problems. We have run suites of collisionless and hydrodynamical simulations of dwarf galaxies evolution in massive host environments to address these issues. We performed controlled, numerical simulations, which mimic the effects of baryons, in order to examine the assumptions implicitly made by dark matter-only simulations. The too big to fail problem is due to the overabundance of relatively massive, dense satellite galaxies found in simulations of Milky Way-like environments. We found that the removal of a small baryonic component from the central regions of forming dwarf spheroidal galaxies and the inclusion of a disk component in the host galaxy can substantially reduce the central dark matter density of satellites, bringing simulations and observations of satellites into agreement. Additionally, we studied hydrodynamical simulations of massive host galaxies and their surrounding dwarf galaxy populations. The VELA simulation suite of cosmological zoom-in simulations is run with the ART code, stochastic star formation, and stellar feedback (supernovae feedback, stellar winds, radiation pressure, and photoionization pressure). The suite includes host galaxies with Mvir(z=0)=1011-10 12M ⊙ and their satellite dwarf galaxies and local isolated dwarf galaxies around each

  15. Observations of offshore bar decay

    DEFF Research Database (Denmark)

    Aagaard, Troels; Kroon, Aart; Greenwood, Brian

    2010-01-01

    Long-term, net offshore bar migration is a common occurrence on many multiple-barred beaches. The first stage of the process involves the generation of a longshore bar close to the shoreline that oscillates about a mean position for some time, followed by a stage of net offshore migration across...... the upper shoreface, and finally a stage of decaying bar form through loss of sediment volume at the outer boundary of the upper shoreface. The phenomenon has been previously documented in the Netherlands, the USA, the Canadian Great Lakes, and in New Zealand, but our present understanding...... of the morphodynamic processes and sediment transport pathways involved in bar decay is limited. In this paper, long-term, net offshore bar migration is investigated at Vejers Beach, located on the North Sea coast of Denmark where offshore bar migration rates are of the order of 45–55 m a-1. A wave height...

  16. Connecting Global to Local Parameters in Barred Galaxy Models

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    The velocity and the angular velocity units are 10 km/s and 10 km/s/kpc, respectively while G is equal to unity. Our test particle is a star of mass = 1. Therefore, the energy unit (per unit mass) is 100(km/s)2. In these units the values of the parameters are α = 12 kpc,b = 2,cb = 1.5 kpc,Md = 9500 and Mb = 3000. It is evident that ...

  17. Application of dynamical system methods to galactic dynamics : from warps to double bars

    OpenAIRE

    Sánchez Martín, Patricia

    2015-01-01

    Most galaxies have a warped shape when they are seen from an edge-on point of view. In this work we apply dynamical system methods to find an explanation of this phenomenon that agrees with its abundance among galaxies, its persistence in time and the angular size of observed warps. Starting from a simple, but realistic, 3D galaxy model formed by a bar and a flat disc, we study the effect produced by a small misalignment between the angular momentum of the system and its angular velocity. ...

  18. VISTA Views the Sculptor Galaxy

    Science.gov (United States)

    2010-06-01

    A spectacular new image of the Sculptor Galaxy (NGC 253) has been taken with the ESO VISTA telescope at the Paranal Observatory in Chile as part of one of its first major observational campaigns. By observing in infrared light VISTA's view is less affected by dust and reveals a myriad of cooler stars as well as a prominent bar of stars across the central region. The VISTA image provides much new information on the history and development of the galaxy. The Sculptor Galaxy (NGC 253) lies in the constellation of the same name and is one of the brightest galaxies in the sky. It is prominent enough to be seen with good binoculars and was discovered by Caroline Herschel from England in 1783. NGC 253 is a spiral galaxy that lies about 13 million light-years away. It is the brightest member of a small collection of galaxies called the Sculptor Group, one of the closest such groupings to our own Local Group of galaxies. Part of its visual prominence comes from its status as a starburst galaxy, one in the throes of rapid star formation. NGC 253 is also very dusty, which obscures the view of many parts of the galaxy (eso0902). Seen from Earth, the galaxy is almost edge on, with the spiral arms clearly visible in the outer parts, along with a bright core at its centre. VISTA, the Visible and Infrared Survey Telescope for Astronomy, the latest addition to ESO's Paranal Observatory in the Chilean Atacama Desert, is the world's largest survey telescope. After being handed over to ESO at the end of 2009 (eso0949) the telescope was used for two detailed studies of small sections of the sky before it embarked on the much larger surveys that are now in progress. One of these "mini surveys" was a detailed study of NGC 253 and its environment. As VISTA works at infrared wavelengths it can see right through most of the dust that is such a prominent feature of the Sculptor Galaxy when viewed in visible light. Huge numbers of cooler stars that are barely detectable with visible

  19. Resolving Gas-Phase Metallicity In Galaxies

    Science.gov (United States)

    Carton, David

    2017-06-01

    Chapter 2: As part of the Bluedisk survey we analyse the radial gas-phase metallicity profiles of 50 late-type galaxies. We compare the metallicity profiles of a sample of HI-rich galaxies against a control sample of HI-'normal' galaxies. We find the metallicity gradient of a galaxy to be strongly correlated with its HI mass fraction {M}{HI}) / {M}_{\\ast}). We note that some galaxies exhibit a steeper metallicity profile in the outer disc than in the inner disc. These galaxies are found in both the HI-rich and control samples. This contradicts a previous indication that these outer drops are exclusive to HI-rich galaxies. These effects are not driven by bars, although we do find some indication that barred galaxies have flatter metallicity profiles. By applying a simple analytical model we are able to account for the variety of metallicity profiles that the two samples present. The success of this model implies that the metallicity in these isolated galaxies may be in a local equilibrium, regulated by star formation. This insight could provide an explanation of the observed local mass-metallicity relation. Chapter 3 We present a method to recover the gas-phase metallicity gradients from integral field spectroscopic (IFS) observations of barely resolved galaxies. We take a forward modelling approach and compare our models to the observed spatial distribution of emission line fluxes, accounting for the degrading effects of seeing and spatial binning. The method is flexible and is not limited to particular emission lines or instruments. We test the model through comparison to synthetic observations and use downgraded observations of nearby galaxies to validate this work. As a proof of concept we also apply the model to real IFS observations of high-redshift galaxies. From our testing we show that the inferred metallicity gradients and central metallicities are fairly insensitive to the assumptions made in the model and that they are reliably recovered for galaxies

  20. Circumnuclear Dust in Nearby Active and Inactive Galaxies. I. Data

    Science.gov (United States)

    Martini, Paul; Regan, Michael W.; Mulchaey, John S.; Pogge, Richard W.

    2003-06-01

    The detailed morphology of the interstellar medium (ISM) in the central kiloparsec of galaxies is controlled by pressure and gravitation. The combination of these forces shapes both circumnuclear star formation and the growth of the central, supermassive black hole. We present visible and near-infrared Hubble Space Telescope images and color maps of 123 nearby galaxies that show the distribution of the cold ISM, as traced by dust, with excellent spatial resolution. These observations reveal that nuclear dust spirals are found in the majority of active and inactive galaxies and they possess a wide range in coherence, symmetry, and pitch angle. We have used this large sample to develop a classification system for circumnuclear dust structures. In spite of the heterogeneous nature of the complete sample, we only find symmetric, two-arm nuclear dust spirals in galaxies with large-scale bars, and these dust lanes clearly connect to dust lanes along the leading edges of the large-scale bars. Not all dust lanes along large-scale bars form two-arm spirals, however, and several instead end in nuclear rings. We find that tightly wound, or low pitch angle, nuclear dust spirals are more common in unbarred galaxies than barred galaxies. Finally, the extended narrow-line region in several of the active galaxies is well resolved. The connection between the ionized gas and circumnuclear dust lanes in four of these galaxies provides additional evidence that a significant fraction of their extended narrow-line region is ambient gas photoionized in situ by the active nucleus. In a future paper we will use our classification system for circumnuclear dust to identify differences between active and inactive galaxies, as well as barred and unbarred galaxies, in well-matched subsamples of these data. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in

  1. Fossil evidence for spin alignment of SDSS galaxies in filaments

    NARCIS (Netherlands)

    Jones, Bernard J.T.; Weygaert, Rien van de; Arag´on-Calvo, Miguel A.

    2010-01-01

    We search for and find fossil evidence that the distribution of the spin axes of galaxies in cosmic web filaments relative to their host filaments are not randomly distributed. This would indicate that the action of large scale tidal torques effected the alignments of galaxies located in cosmic

  2. Starburst radio galaxies : General properties, evolutionary histories and triggering

    NARCIS (Netherlands)

    Tadhunter, C.; Holt, J.; González Delgado, R.; Rodríguez Zaurín, J.; Villar-Martín, M.; Morganti, R.; Emonts, B.; Ramos Almeida, C.; Inskip, K.

    In this paper we discuss the results of a programme of spectral synthesis modelling of a sample of starburst radio galaxies in the context of scenarios for the triggering of the activity and the evolution of the host galaxies. New optical spectra are also presented for a subset of the objects

  3. Peering Into an Early Galaxy

    Science.gov (United States)

    Kohler, Susanna

    2018-04-01

    Thirteen billion years ago, early galaxies ionized the gas around them, producing some of the first light that brought our universe out of its dark ages. Now the Atacama Large Millimeter/submillimeter Array (ALMA) has provided one of the first detailed looks into the interior of one of these early, distant galaxies.Sources of LightArtists illustration of the reionization of the universe (time progresses left to right), in which ionized bubbles that form around the first sources of light eventually overlap to form the fully ionized universe we observe today. [Avi Loeb/Scientific American]For the first roughly hundred million years of its existence, our universe expanded in relative darkness there were no sources of light at that time besides the cosmic microwave background. But as mass started to condense to form the first objects, these objects eventually shone as the earliest luminous sources, contributing to the reionization of the universe.To learn about the early production of light in the universe, our best bet is to study in detail the earliest luminous sources stars, galaxies, or quasars that we can hunt down. One ideal target is the galaxy COSMOS Redshift 7, known as CR7 for short.Targeting CR7CR7 is one of the oldest, most distant galaxies known, lying at a redshift of z 6.6. Its discovery in 2015 and subsequent observations of bright, ultraviolet-emitting clumps within it have led to broad speculation about the source of its emission. Does this galaxy host an active nucleus? Or could it perhaps contain the long-theorized first generation of stars, metal-free Population III stars?To determine the nature of CR7 and the other early galaxies that contributed to reionization, we need to explore their gas and dust in detail a daunting task for such distant sources! Conveniently, this is a challenge that is now made possible by ALMAs incredible capabilities. In a new publication led by Jorryt Matthee (Leiden University, the Netherlands), a team of scientists now

  4. Dense Molecular Gas and H2O Maser Emission in Galaxies F ...

    Indian Academy of Sciences (India)

    Our analysis results show that there is no significant difference on the infrared and gas emission between maser galaxies and galaxies without maser detection. For maser host HCN- galaxies, maser luminosity is found to be correlated to CO luminosity. (a proxy of the total molecular gas) and HCN luminosity, i.e., kilomasers.

  5. CGCG 292-057: A Near-Distance Merger Galaxy with Double ...

    Indian Academy of Sciences (India)

    Interestingly, the host of this source is a near-distance bright galaxy named CGCG292-057, which is clearly disturbed, with tidal features and shells as plausible signs of a recent merger. Key words. Galaxies: active—individual: CGCG 292-057. 1. Introduction. Galaxy mergers and interactions are main triggers for many of ...

  6. Merger-origin of radio galaxies investigated with H I observation

    NARCIS (Netherlands)

    Emonts, B.H.C.; Morganti, R.; Oosterloo, T.; Hulst, J.M. van der; Tadhunter, C.N.; Moorsel, G. van; Holt, J.; hOLT, j.

    2005-01-01

    Abstract: We present results of an HI study of a complete sample of nearby radio galaxies. Our goal is to investigate whether merger or interaction events could be at the origin of the radio-AGN activity. Around five of our radio galaxies, hosted mainly by early-type galaxies, we detect extended HI

  7. Ukola Club. Bar americano

    Directory of Open Access Journals (Sweden)

    Azpiazu, J. R.

    1961-03-01

    Full Text Available En la calle de Serrano, aprovechando un semisótano dedicado a otro negocio anteriormente, se ha instalado un bar americano, de cuyo interior ofrecemos algunos pormenores. Se han cuidado, especialmente, las condiciones acústicas, resueltas por medio de un techo de escayola perforada, con vitrofib en su parte superior, y paredes de madera, que contribuyen a darle un ambiente cálido y acogedor. El soporte de hierro laminado existente en el centro del local, cuya supresión hubiera sido costosa, se ha revestido con lajas de mármol que le convierten en un elemento decorativo.

  8. CERN access cards - Introduction of a bar code (Reminder)

    CERN Multimedia

    Relations with the Host States Service

    2004-01-01

    In accordance with the latest revised version of the implementation measures relating to Operational Circular No. 2, CERN access cards may bear a bar code transcribing the holder's identification number (the revised version of this subsidiary document to the aforementioned Circular will be published shortly). Relations with the Host States Service http://www.cern.ch/relations/ relations.secretariat@cern.ch Tel. 72848

  9. CERN access card: Introduction of a bar code

    CERN Multimedia

    Relations with the Host States Service

    2004-01-01

    Before the latest version of the implementation measures relating to Operational Circular No. 2 comes into force, we would like to inform you that, in future, CERN access cards may bear a bar code to transcribe the holder's identification number. Relations with the Host States Service http://www.cern.ch/relations/ Tel. 72848

  10. Galaxy Mergers Moulding the CGM

    Science.gov (United States)

    Hani, Maan H.; Sparre, Martin; Ellison, Sara L.; Torrey, Paul; Vogelsberger, Mark

    2017-07-01

    Galaxies are surrounded by sizeable gas reservoirs which host a significant amount of metals: the circum-galactic medium (CGM). The CGM acts as a mediator between the galaxy and the extra-galactic medium. However, our understanding of how galaxy mergers, a major evolutionary transformation, impact the CGM remains deficient. We present a theoretical study of the effect of galaxy mergers on the CGM: We use hydrodynamical cosmological zoom-in simulations of a major merger selected from the Illustris project such that the z=0 descendant is a Milky Way-like galaxy, and then re-simulated at a 40 times higher mass resolution. We include post-processing ionization modelling. This work demonstrates the effect the merger has on the characteristic size of the CGM, its metallicity and the predicted covering fraction of various commonly observed gas-phase species, such as H I, C IV and O VI. We show that merger-induced outflows can increase the CGM metallicity by 0.2-0.3 dex within 0.5 Gyr post-merger. These effects last up to 6 Gyr post-merger. While the merger increases the total metal covering fractions by factors of 2-3, the covering fractions of commonly observed UV ions decrease due to the hard ionizing radiation from the active galactic nucleus. The case study of the single simulated major merger presented in this work demonstrates the significant impact that a galaxy interaction can have on the size, metallicity and observed column densities of the CGM (Hani et al. in prep).

  11. DAMPING OF THE MILKY WAY BAR BY MANIFOLD-DRIVEN SPIRALS

    Energy Technology Data Exchange (ETDEWEB)

    Łokas, Ewa L. [Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Bartycka 18, 00-716 Warsaw (Poland)

    2016-10-10

    We describe a new phenomenon of “bar damping” that may have played an important role in shaping the Milky Way bar and bulge as well as its spiral structure. We use a collisionless N -body simulation of a Milky Way–like galaxy initially composed of a dark matter halo and an exponential disk with a Toomre parameter slightly above unity. In this configuration, dominated by the disk in the center, a bar forms relatively quickly, after 1 Gyr of evolution. This is immediately followed by the formation of two manifold-driven spiral arms and the outflow of stars that modifies the potential in the vicinity of the bar, apparently shifting the position of the L {sub 1}/ L {sub 2} Lagrange points. This modification leads to the shortening of the bar and the creation of a next generation of manifold-driven spiral arms at a smaller radius. The process repeats itself a few times over the next 0.5 Gyr resulting in further substantial weakening and shortening of the bar. The time when the damping comes to an end coincides with the first buckling episode in the bar that rebuilds the orbital structure so that no more new spiral arms are formed. The morphology of the bar and the spiral structure at this time show remarkable similarity to the present properties of the Milky Way. Later on, the bar starts to grow rather steadily again, weakened only by subsequent buckling episodes occurring at more distant parts of the disk.

  12. Shape of LOSVDs in Barred Disks: Implications for Future IFU Surveys

    Science.gov (United States)

    Li, Zhao-Yu; Shen, Juntai; Bureau, Martin; Zhou, Yingying; Du, Min; Debattista, Victor P.

    2018-02-01

    The shape of line-of-sight velocity distributions (LOSVDs) carries important information about the internal dynamics of galaxies. The skewness of LOSVDs represents their asymmetric deviation from a Gaussian profile. Correlations between the skewness parameter (h 3) and the mean velocity (\\overline{V}) of a Gauss–Hermite series reflect the underlying stellar orbital configurations of different morphological components. Using two self-consistent N-body simulations of disk galaxies with different bar strengths, we investigate {h}3-\\overline{V} correlations at different inclination angles. Similar to previous studies, we find anticorrelations in the disk area, and positive correlations in the bar area when viewed edge-on. However, at intermediate inclinations, the outer parts of bars exhibit anticorrelations, while the core areas dominated by the boxy/peanut-shaped (B/PS) bulges still maintain weak positive correlations. When viewed edge-on, particles in the foreground/background disk (the wing region) in the bar area constitute the main velocity peak, whereas the particles in the bar contribute to the high-velocity tail, generating the {h}3-\\overline{V} correlation. If we remove the wing particles, the LOSVDs of the particles in the outer part of the bar only exhibit a low-velocity tail, resulting in a negative {h}3-\\overline{V} correlation, whereas the core areas in the central region still show weakly positive correlations. We discuss implications for IFU observations on bars, and show that the variation of the {h}3-\\overline{V} correlation in the disk galaxy may be used as a kinematic indicator of the bar and the B/PS bulge.

  13. INTEGRAL-FIELD STELLAR AND IONIZED GAS KINEMATICS OF PECULIAR VIRGO CLUSTER SPIRAL GALAXIES

    International Nuclear Information System (INIS)

    Cortés, Juan R.; Hardy, Eduardo; Kenney, Jeffrey D. P.

    2015-01-01

    We present the stellar and ionized gas kinematics of 13 bright peculiar Virgo cluster galaxies observed with the DensePak Integral Field Unit at the WIYN 3.5 m telescope in order to look for kinematic evidence that these galaxies have experienced gravitational interactions or gas stripping. Two-dimensional maps of the stellar velocity V, stellar velocity dispersion σ, and the ionized gas velocity (Hβ and/or [O III]) are presented for the galaxies in the sample. The stellar rotation curves and velocity dispersion profiles are determined for 13 galaxies, and the ionized gas rotation curves are determined for 6 galaxies. Misalignments between the optical and kinematical major axes are found in several galaxies. While in some cases this is due to a bar, in other cases it seems to be associated with gravitational interaction or ongoing ram pressure stripping. Non-circular gas motions are found in nine galaxies, with various causes including bars, nuclear outflows, or gravitational disturbances. Several galaxies have signatures of kinematically distinct stellar components, which are likely signatures of accretion or mergers. For all of our galaxies, we compute the angular momentum parameter λ R . An evaluation of the galaxies in the λ R ellipticity plane shows that all but two of the galaxies have significant support from random stellar motions, and have likely experienced gravitational interactions. This includes some galaxies with very small bulges and truncated/compact Hα morphologies, indicating that such galaxies cannot be fully explained by simple ram pressure stripping, but must have had significant gravitational encounters. Most of the sample galaxies show evidence for ICM-ISM stripping as well as gravitational interactions, indicating that the evolution of a significant fraction of cluster galaxies is likely strongly impacted by both effects

  14. Bar piezoelectric ceramic transformers.

    Science.gov (United States)

    Erhart, Jiří; Pulpan, Půlpán; Rusin, Luboš

    2013-07-01

    Bar-shaped piezoelectric ceramic transformers (PTs) working in the longitudinal vibration mode (k31 mode) were studied. Two types of the transformer were designed--one with the electrode divided into two segments of different length, and one with the electrodes divided into three symmetrical segments. Parameters of studied transformers such as efficiency, transformation ratio, and input and output impedances were measured. An analytical model was developed for PT parameter calculation for both two- and three-segment PTs. Neither type of bar PT exhibited very high efficiency (maximum 72% for three-segment PT design) at a relatively high transformation ratio (it is 4 for two-segment PT and 2 for three-segment PT at the fundamental resonance mode). The optimum resistive loads were 20 and 10 kΩ for two- and three-segment PT designs for the fundamental resonance, respectively, and about one order of magnitude smaller for the higher overtone (i.e., 2 kΩ and 500 Ω, respectively). The no-load transformation ratio was less than 27 (maximum for two-segment electrode PT design). The optimum input electrode aspect ratios (0.48 for three-segment PT and 0.63 for two-segment PT) were calculated numerically under no-load conditions.

  15. Globular Clusters for Faint Galaxies

    Science.gov (United States)

    Kohler, Susanna

    2017-07-01

    .The most striking feature of these galaxies, however, is that they are surrounded by a large number of compact objects that appear to be globular clusters. From the observations, Van Dokkum and collaborators estimate that Dragonfly 44 and DFX1 have approximately 74 and 62 globulars, respectively significantly more than the low numbers expected for galaxies of this luminosity.Armed with this knowledge, the authors went back and looked at archival observations of 14 other UDGs also located in the Coma cluster. They found that these smaller and fainter galaxies dont host quite as many globular clusters as Dragonfly 44 and DFX1, but more than half also show significant overdensities of globulars.Main panel: relation between the number of globular clusters and total absolute magnitude for Coma UDGs (solid symbols) compared to normal galaxies (open symbols). Top panel: relation between effective radius and absolute magnitude. The UDGs are significantly larger and have more globular clusters than normal galaxies of the same luminosity. [van Dokkum et al. 2017]Evidence of FailureIn general, UDGs appear to have more globular clusters than other galaxies of the same total luminosity, by a factor of nearly 7. These results are consistent with the scenario in which UDGs are failed galaxies: they likely have the halo mass to have formed a large number of globular clusters, but they were quenched before they formed a disk and bulge. Because star formation never got going in UDGs, they are now much dimmer than other galaxies of the same size.The authors suggest that the next step is to obtain dynamical measurements of the UDGs to determine whether these faint galaxies really do have the halo mass suggested by their large numbers of globulars. Future observations will continue to help us pin down the origin of these dim giants.CitationPieter van Dokkum et al 2017 ApJL 844 L11. doi:10.3847/2041-8213/aa7ca2

  16. ON THE RATES OF TYPE Ia SUPERNOVAE IN DWARF AND GIANT HOSTS WITH ROTSE-IIIb

    International Nuclear Information System (INIS)

    Quimby, Robert M.; Yuan Fang; Akerlof, Carl; Wheeler, J. Craig; Warren, Michael S.

    2012-01-01

    We present a sample of 23 spectroscopically confirmed Type Ia supernovae (SNe Ia) that were discovered in the background of galaxy clusters targeted by ROTSE-IIIb and use up to 18 of these to determine the local (z-bar 0.05) volumetric rate. Since our survey is flux limited and thus biased against fainter objects, the pseudo-absolute magnitude distribution (pAMD) of SNe Ia in a given volume is an important concern, especially the relative frequency of high- to low-luminosity SNe Ia. We find that the pAMD derived from the volume-limited Lick Observatory Supernova Search (LOSS) sample is incompatible with the distribution of SNe Ia in a volume-limited (z B > –16) galaxies, whereas only 1 out of 79 nearby SDSS-II SNe Ia have such faint hosts. It is possible that previous works have undercounted either low-luminosity SNe Ia, SNe Ia in low-luminosity hosts, or peculiar SNe Ia (sometimes explicitly), and the total SNe Ia rate may be higher than the canonical value.

  17. Dwarf Galaxies in Voids: Dark Matter Halos and Gas Cooling

    Directory of Open Access Journals (Sweden)

    Matthias Hoeft

    2010-01-01

    Full Text Available Galaxy surveys have shown that luminous galaxies are mainly distributed in large filaments and galaxy clusters. The remaining large volumes are virtually devoid of luminous galaxies. This is in concordance with the formation of the large-scale structure in the universe as derived from cosmological simulations. However, the numerical results indicate that cosmological voids are abundantly populated with dark matter haloes which may in principle host dwarf galaxies. Observational efforts have in contrast revealed that voids are apparently devoid of dwarf galaxies. We investigate the formation of dwarf galaxies in voids by hydrodynamical cosmological simulations. Due to the cosmic ultraviolet background radiation low-mass haloes show generally a reduced baryon fraction. We determine the characteristic mass below which dwarf galaxies are baryon deficient. We show that the circular velocity below which the accretion of baryons is suppressed is approximately 40 kms−1. The suppressed baryon accretion is caused by the photo-heating due to the UV background. We set up a spherical halo model and show that the effective equation of the state of the gas in the periphery of dwarf galaxies determines the characteristic mass. This implies that any process which heats the gas around dwarf galaxies increases the characteristic mass and thus reduces the number of observable dwarf galaxies.

  18. Brightest Cluster Galaxies in REXCESS Clusters

    Science.gov (United States)

    Haarsma, Deborah B.; Leisman, L.; Bruch, S.; Donahue, M.

    2009-01-01

    Most galaxy clusters contain a Brightest Cluster Galaxy (BCG) which is larger than the other cluster ellipticals and has a more extended profile. In the hierarchical model, the BCG forms through many galaxy mergers in the crowded center of the cluster, and thus its properties give insight into the assembly of the cluster as a whole. In this project, we are working with the Representative XMM-Newton Cluster Structure Survey (REXCESS) team (Boehringer et al 2007) to study BCGs in 33 X-ray luminous galaxy clusters, 0.055 < z < 0.183. We are imaging the BCGs in R band at the Southern Observatory for Astrophysical Research (SOAR) in Chile. In this poster, we discuss our methods and give preliminary measurements of the BCG magnitudes, morphology, and stellar mass. We compare these BCG properties with the properties of their host clusters, particularly of the X-ray emitting gas.

  19. In Pursuit of the Least Luminous Galaxies

    Directory of Open Access Journals (Sweden)

    Beth Willman

    2010-01-01

    Full Text Available The dwarf galaxy companions to the Milky Way are unique cosmological laboratories. With luminosities as low as 10−7LMW, they inhabit the lowest mass dark matter halos known to host stars and are presently the most direct tracers of the distribution, mass spectrum, and clustering scale of dark matter. Their resolved stellar populations also facilitate detailed studies of their history and mass content. To fully exploit this potential requires a well-defined census of virtually invisible galaxies to the faintest possible limits and to the largest possible distances. I review the past and present impacts of survey astronomy on the census of Milky Way dwarf galaxy companions and discuss the future of finding ultra-faint dwarf galaxies around the Milky Way and beyond in wide-field survey data.

  20. Jet-induced star formation in gas-rich galaxies

    OpenAIRE

    Gaibler, Volker; Khochfar, Sadegh; Krause, Martin; Silk, Joseph

    2011-01-01

    Feedback from active galactic nuclei (AGN) has become a major component in simulations of galaxy evolution, in particular for massive galaxies. AGN jets have been shown to provide a large amount of energy and are capable of quenching cooling flows. Their impact on the host galaxy, however, is still not understood. Subgrid models of AGN activity in a galaxy evolution context so far have been mostly focused on the quenching of star formation. To shed more light on the actual physics of the "rad...

  1. Neutral Hydrogen in Local Group Dwarf Galaxies

    Science.gov (United States)

    Grcevich, Jana

    The gas content of the faintest and lowest mass dwarf galaxies provide means to study the evolution of these unique objects. The evolutionary histories of low mass dwarf galaxies are interesting in their own right, but may also provide insight into fundamental cosmological problems. These include the nature of dark matter, the disagreement between the number of observed Local Group dwarf galaxies and that predicted by lambda cold dark matter models, and the discrepancy between the observed census of baryonic matter in the Milky Way's environment and theoretical predictions. This thesis explores these questions by studying the neutral hydrogen (HI) component of dwarf galaxies. First, limits on the HI mass of the ultra-faint dwarfs are presented, and the HI content of all Local Group dwarf galaxies is examined from an environmental standpoint. We find that those Local Group dwarfs within 270 kpc of a massive host galaxy are deficient in HI as compared to those at larger galactocentric distances. Ram-pressure arguments are invoked, which suggest halo densities greater than 2-3 x 10-4 cm-3 out to distances of at least 70 kpc, values which are consistent with theoretical models and suggest the halo may harbor a large fraction of the host galaxy's baryons. We also find that accounting for the incompleteness of the dwarf galaxy count, known dwarf galaxies whose gas has been removed could have provided at most 2.1 x 108 M⊙ of HI gas to the Milky Way. Second, we examine the possibility of discovering unknown gas-rich ultra-faint galaxies in the Local Group using HI. The GALFA-HI Survey catalog is searched for compact, isolated HI clouds which are most similar to the expected HI characteristics of low mass dwarf galaxies. Fifty-one Local Group dwarf galaxy candidates are identified through column density, brightness temperature, and kinematic selection criteria, and their properties are explored. Third, we present hydrodynamic simulations of dwarf galaxies experiencing a

  2. PKS 1814-637: a powerful radio-loud AGN in a disk galaxy

    NARCIS (Netherlands)

    Morganti, R.; Holt, J.; Tadhunter, C.; Almeida, C. Ramos; Dicken, D.; Inskip, K.; Oosterloo, T.; Tzioumis, T.

    2011-01-01

    We present a detailed study of PKS 1814-637, a rare case of powerful radio source (P5 GHz = 4.1 × 1025 W Hz-1) hosted by a disk galaxy. Optical images have been used to model the host galaxy morphology confirming it to be dominated by a strong (and warped) disk component that is observed close to

  3. The dark side of galaxy colour: evidence from new SDSS measurements of galaxy clustering and lensing

    Energy Technology Data Exchange (ETDEWEB)

    Hearin, Andrew P. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States). Fermilab Center for Particle Astrophysics; Watson, Douglas F. [Univ. of Chicago, IL (United States). Kavli Inst. for Cosmological Physics (KICP); Becker, Matthew R. [Univ. of Chicago, IL (United States). Kavli Inst. for Cosmological Physics (KICP); KICP, Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Reyes, Reinabelle [Univ. of Chicago, IL (United States). Kavli Inst. for Cosmological Physics (KICP); Berlind, Andreas A. [Vanderbilt Univ., Nashville, TN (United States). Dept. of Physics and Astronomy; Zentner, Andrew R. [Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT PACC), PA (United States)

    2014-08-12

    The age matching model has recently been shown to predict correctly the luminosity L and g-r color of galaxies residing within dark matter halos. The central tenet of the model is intuitive: older halos tend to host galaxies with older stellar populations. In this paper, we demonstrate that age matching also correctly predicts the g-r color trends exhibited in a wide variety of statistics of the galaxy distribution for stellar mass M* threshold samples. In particular, we present new measurements of the galaxy two-point correlation function and the galaxy-galaxy lensing signal as a function of M* and g-r color from the Sloan Digital Sky Survey, and show that age matching exhibits remarkable agreement with these and other statistics of low-redshift galaxies. In so doing, we also demonstrate good agreement between the galaxy-galaxy lensing observed by SDSS and the signal predicted by abundance matching, a new success of this model. We describe how age matching is a specific example of a larger class of Conditional Abundance Matching models (CAM), a theoretical framework we introduce here for the first time. CAM provides a general formalism to study correlations at fixed mass between any galaxy property and any halo property. The striking success of our simple implementation of CAM provides compelling evidence that this technique has the potential to describe the same set of data as alternative models, but with a dramatic reduction in the required number of parameters. CAM achieves this reduction by exploiting the capability of contemporary N-body simulations to determine dark matter halo properties other than mass alone, which distinguishes our model from conventional approaches to the galaxy-halo connection.

  4. Age bimodality in the central region of pseudo-bulges in S0 galaxies

    Science.gov (United States)

    Mishra, Preetish K.; Barway, Sudhanshu; Wadadekar, Yogesh

    2017-11-01

    We present evidence for bimodal stellar age distribution of pseudo-bulges of S0 galaxies as probed by the Dn(4000) index. We do not observe any bimodality in age distribution for pseudo-bulges in spiral galaxies. Our sample is flux limited and contains 2067 S0 and 2630 spiral galaxies drawn from the Sloan Digital Sky Survey. We identify pseudo-bulges in S0 and spiral galaxies, based on the position of the bulge on the Kormendy diagram and their central velocity dispersion. Dividing the pseudo-bulges of S0 galaxies into those containing old and young stellar populations, we study the connection between global star formation and pseudo-bulge age on the u - r colour-mass diagram. We find that most old pseudo-bulges are hosted by passive galaxies while majority of young bulges are hosted by galaxies that are star forming. Dividing our sample of S0 galaxies into early-type S0s and S0/a galaxies, we find that old pseudo-bulges are mainly hosted by early-type S0 galaxies while most of the pseudo-bulges in S0/a galaxies are young. We speculate that morphology plays a strong role in quenching of star formation in the disc of these S0 galaxies, which stops the growth of pseudo-bulges, giving rise to old pseudo-bulges and the observed age bimodality.

  5. Implementation of viscoelastic Hopkinson bars

    Directory of Open Access Journals (Sweden)

    Govender R.

    2012-08-01

    Full Text Available Knowledge of the properties of soft, viscoelastic materials at high strain rates are important in furthering our understanding of their role during blast or impact events. Testing these low impedance materials using a metallic split Hopkinson pressure bar setup results in poor signal to noise ratios due to impedance mismatching. These difficulties are overcome by using polymeric Hopkinson bars. Conventional Hopkinson bar analysis cannot be used on the polymeric bars due to the viscoelastic nature of the bar material. Implementing polymeric Hopkinson bars requires characterization of the viscoelastic properties of the material used. In this paper, 30 mm diameter Polymethyl Methacrylate bars are used as Hopkinson pressure bars. This testing technique is applied to polymeric foam called Divinycell H80 and H200. Although there is a large body of of literature containing compressive data, this rarely deals with strain rates above 250s−1 which becomes increasingly important when looking at the design of composite structures where energy absorption during impact events is high on the list of priorities. Testing of polymeric foams at high strain rates allows for the development of better constitutive models.

  6. Dark matter in central galaxies

    Science.gov (United States)

    Salinas, R.; Richtler, T.; Romanowsky, A. J.; Schuberth, Y.; Gomez, M.; Hilker, M.

    The study of the dynamics of globular clusters systems (GCSs) is a powerful tool to test the dark matter (DM) content at galactic scales, especially in early type galaxies which present a lack of suitable DM probes (Romanowsky 2006). So far, this method has been only applied to a handful of nearby ellipticals, mainly due to the observational difficulties (Cote et al. 2001; Richtler et al. 2004; Schuberth et al. 2006; Woodley et al. 2007). In this talk I will present the first results of our VLT-VIMOS study of the dynamics of the GCS of NGC 3311, the nearest cD galaxy, which hosts an enormous GC population (McLaughlin et al. 1995). These results include the spectroscopic confirmation of the first ultra compact dwarf in Hydra I, from the candidate list of Wehner & Harris (2007).

  7. Origin of the high vlos feature in the Galactic bar

    Science.gov (United States)

    Aumer, Michael; Schönrich, Ralph

    2015-12-01

    We analyse a controlled N-body+smoothed particle hydrodynamics simulation of a growing disc galaxy within a non-growing, live dark halo. The disc is continuously fed with gas and star particles on near-circular orbits and develops a bar comparable in size to the one of the Milky Way (MW). We extract line-of-sight velocity vlos distributions from the model and compare it to data recently obtained from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey which show distinct high-velocity features around vlos ˜ 200 km s-1. With an APOGEE-like selection function, but without any scaling nor adjustment, we find vlos distributions very similar to those in APOGEE. The stars that make up the high vlos features at positive longitudes l are preferentially young bar stars (age τ ≲ 2-3 Gyr) which move away from us along the rear side of the bar. At negative l, we find the corresponding low vlos feature from stars moving towards us. At l > 10 deg, the highest vlos stars are a mixture of bar and background disc stars which complicates the interpretation of observations. The main peak in vlos is dominated by fore- and background stars. At a given time, ˜40-50 per cent of high vlos stars occupy x1-like orbits, but a significant fraction are on more complex orbits. The observed feature is likely due to a population of dynamically cool, young stars formed from gas just outside the bar and subsequently captured by the growing bar. The high vlos features disappear at high latitudes |b| ≳ 2 deg which explains the non-detection of such features in other surveys.

  8. Combining Galaxy-Galaxy Lensing and Galaxy Clustering

    Energy Technology Data Exchange (ETDEWEB)

    Park, Youngsoo [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Krause, Elisabeth [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Dodelson, Scott [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Jain, Bhuvnesh [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Amara, Adam [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Becker, Matt [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Bridle, Sarah [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Clampitt, Joseph [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Crocce, Martin [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Honscheid, Klaus [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Gaztanaga, Enrique [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Sanchez, Carles [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Wechsler, Risa [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-01-01

    Combining galaxy-galaxy lensing and galaxy clustering is a promising method for inferring the growth rate of large scale structure, a quantity that will shed light on the mechanism driving the acceleration of the Universe. The Dark Energy Survey (DES) is a prime candidate for such an analysis, with its measurements of both the distribution of galaxies on the sky and the tangential shears of background galaxies induced by these foreground lenses. By constructing an end-to-end analysis that combines large-scale galaxy clustering and small-scale galaxy-galaxy lensing, we also forecast the potential of a combined probes analysis on DES datasets. In particular, we develop a practical approach to a DES combined probes analysis by jointly modeling the assumptions and systematics affecting the different components of the data vector, employing a shared halo model, HOD parametrization, photometric redshift errors, and shear measurement errors. Furthermore, we study the effect of external priors on different subsets of these parameters. We conclude that DES data will provide powerful constraints on the evolution of structure growth in the universe, conservatively/ optimistically constraining the growth function to 8%/4.9% with its first-year data covering 1000 square degrees, and to 4%/2.3% with its full five-year data covering 5000 square degrees.

  9. Bar Coliseo, en Sevilla

    Directory of Open Access Journals (Sweden)

    de la Peña Neila, Antonio

    1963-10-01

    Full Text Available This bar is situated inside the «Coliseo» building, which houses a cinema, as well as a number of commercial establishments. In order not to break the unity of the total project, no attempt has been made to alter the exterior aspect of the bar. No attempt was made, either, to make it into an intimate, club type of bar, now so much in fashion. Rather has it been given a diaphanous style, seeking the best possible use of the floor space. The windows of the building are elongated, and there is an intermediate floor level, whose detailed structure is metallic. A cleverly designed staircase, of folded sheet metal connects the ground floor, the intermediate floor level and the restaurant. Materials were carefully chosen in accordance with their function. The colour scheme has a sustained unity throughout the building, and care has been taken to avoid surprising or vivid chromatic patterns. Ceramic enamels by the painter Santiago del Campo provide a feature of decoration on the ground floor, and also serve to cover up the return air ducts. On the top floor, the restaurant is fitted with coloured tile facings, the work of the Seville painters Maria Josefa Sánchez, María Dolores Sánchez and Emilio García Ortiz. The bottom joints of the timber beams, in conjunction with the tile patterns, is reminiscent of the traditional Sevillian habit of placing ceramic units between the timber framework of buildings. The initial problem of the architect was to combine the optimum functional efficiency and aesthetic quality of the project, and the final solution is undoubtedly successful.El establecimiento está situado dentro del edificio «Coliseo», complejo formado por una sala de cine, y con la parte lateral destinada a locales comerciales. Formando un conjunto único no se pensó nunca en transformar los revestimientos y molduras de fachada. Tampoco presidió la idea de conseguir un establecimiento íntimo «tipo Club», tan en boga actualmente, sino un

  10. Galaxy Structure, Dark Matter, and Galaxy Formation

    OpenAIRE

    Weinberg, David H.

    1996-01-01

    The structure of galaxies, the nature of dark matter, and the physics of galaxy formation were the interlocking themes of DM 1996: Dark and Visible Matter in Galaxies and Cosmological Implications. In this conference summary report, I review recent observational and theoretical advances in these areas, then describe highlights of the meeting and discuss their implications. I include as an appendix the lyrics of The Dark Matter Rap: A Cosmological History for the MTV Generation.

  11. SHINING LIGHT ON MERGING GALAXIES. I. THE ONGOING MERGER OF A QUASAR WITH A 'GREEN VALLEY' GALAXY

    International Nuclear Information System (INIS)

    Da Silva, Robert L.; Xavier Prochaska, J.; Rosario, David; Tumlinson, Jason; Tripp, Todd M.

    2011-01-01

    Serendipitous observations of a pair z = 0.37 interacting galaxies (one hosting a quasar) show a massive gaseous bridge of material connecting the two objects. This bridge is photoionized by the quasar (QSO), revealing gas along the entire projected 38 h -1 70 kpc sightline connecting the two galaxies. The emission lines that result give an unprecedented opportunity to study the merger process at this redshift. We determine the kinematics, ionization parameter (log U ∼ -2.5 ± 0.03), column density (N H,perpendicular ∼ 10 21 cm -2 ), metallicity ([M/H] ∼ - 0.20 ± 0.15), and mass (∼10 8 M sun ) of the gaseous bridge. We simultaneously constrain properties of the QSO host (M DM > 8.8 x 10 11 M sun ) and its companion galaxy (M DM > 2.1 x 10 11 M sun ; M * ∼ 2 x 10 10 M sun ; stellar burst age = 300-800 Myr; SFR ∼6 M sun yr -1 ; and metallicity 12 + log (O/H) = 8.64 ± 0.2). The general properties of this system match the standard paradigm of a galaxy-galaxy merger caught between first and second passages while one of the galaxies hosts an active quasar. The companion galaxy lies in the so-called green valley, with a stellar population consistent with a recent starburst triggered during the first passage of the merger and has no discernible active galactic nucleus activity. In addition to providing case studies of quasars associated with galaxy mergers, quasar/galaxy pairs with QSO-photoionized tidal bridges such as this one offer unique insights into the galaxy properties while also distinguishing an important and inadequately understood phase of galaxy evolution.

  12. Evaluation of longitudinal joint tie bar system.

    Science.gov (United States)

    2011-09-01

    "An adequate longitudinal joint tie bar system is essential in the overall performance of concrete pavement. Excessive : longitudinal joint openings are believed to be caused by either inadequate tie bar size or spacing or improper tie bar : installa...

  13. Does the galaxy-halo connection vary with environment?

    Science.gov (United States)

    Dragomir, Radu; Rodríguez-Puebla, Aldo; Primack, Joel R.; Lee, Christoph T.

    2018-05-01

    (Sub)halo abundance matching (SHAM) assumes that one (sub) halo property, such as mass Mvir or peak circular velocity Vpeak, determines properties of the galaxy hosted in each (sub) halo such as its luminosity or stellar mass. This assumption implies that the dependence of galaxy luminosity functions (GLFs) and the galaxy stellar mass function (GSMF) on environmental density is determined by the corresponding halo density dependence. In this paper, we test this by determining from a Sloan Digital Sky Survey sample the observed dependence with environmental density of the ugriz GLFs and GSMF for all galaxies, and for central and satellite galaxies separately. We then show that the SHAM predictions are in remarkable agreement with these observations, even when the galaxy population is divided between central and satellite galaxies. However, we show that SHAM fails to reproduce the correct dependence between environmental density and g - r colour for all galaxies and central galaxies, although it better reproduces the colour dependence on environmental density of satellite galaxies.

  14. A chiral q-bar q-bar qq nonet?

    International Nuclear Information System (INIS)

    Napsuciale, Mauro; Rodriguez, Simon

    2004-01-01

    We point out that meson spectrum indicates the existence of a degenerate chiral nonet in the energy region around 1.4 GeV with a slightly inverted spectrum with respect to a q-bar q nonet. Based on this observation and the approximately linear rising of the mass of a hadron with the number of constituent quarks we conjecture the existence of a tetraquark chiral nonet in this energy region with chiral symmetry implemented directly. We realize this idea in a chiral model and take into account the mixing of the tetraquark chiral nonet with a conventional q-bar q nonet. We find that the mass spectrum of mesons below 1.5 GeV is consistent with this picture. In general, pseudoscalar states arise as mainly q-bar q states but scalar states turn out to be strong admixtures of q-bar q and tetraquark states

  15. Galaxy bias from the Dark Energy Survey Science Verification data: combining galaxy density maps and weak lensing maps

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C.; Pujol, A.; Gaztañaga, E.; Amara, A.; Réfrégier, A.; Bacon, D.; Becker, M. R.; Bonnett, C.; Carretero, J.; Castander, F. J.; Crocce, M.; Fosalba, P.; Giannantonio, T.; Hartley, W.; Jarvis, M.; Kacprzak, T.; Ross, A. J.; Sheldon, E.; Troxel, M. A.; Vikram, V.; Zuntz, J.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Annis, J.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Rosell, A. Carnero; Kind, M. Carrasco; Cunha, C. E.; D' Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Eifler, T. F.; Estrada, J.; Evrard, A. E.; Flaugher, B.; Frieman, J.; Goldstein, D. A.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; Jain, B.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Lima, M.; Marshall, J. L.; Martini, P.; Melchior, P.; Miller, C. J.; Miquel, R.; Mohr, J. J.; Nichol, R. C.; Nord, B.; Ogando, R.; Plazas, A. A.; Reil, K.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Walker, A. R.

    2016-04-15

    We measure the redshift evolution of galaxy bias from a magnitude-limited galaxy sample by combining the galaxy density maps and weak lensing shear maps for a $\\sim$116 deg$^{2}$ area of the Dark Energy Survey (DES) Science Verification data. This method was first developed in Amara et al. (2012) and later re-examined in a companion paper (Pujol et al., in prep) with rigorous simulation tests and analytical treatment of tomographic measurements. In this work we apply this method to the DES SV data and measure the galaxy bias for a magnitude-limited galaxy sample. We find the galaxy bias and 1$\\sigma$ error bars in 4 photometric redshift bins to be 1.33$\\pm$0.18 (z=0.2-0.4), 1.19$\\pm$0.23 (z=0.4-0.6), 0.99$\\pm$0.36 ( z=0.6-0.8), and 1.66$\\pm$0.56 (z=0.8-1.0). These measurements are consistent at the 1-2$\\sigma$ level with mea- surements on the same dataset using galaxy clustering and cross-correlation of galaxies with CMB lensing. In addition, our method provides the only $\\sigma_8$-independent constraint among the three. We forward-model the main observational effects using mock galaxy catalogs by including shape noise, photo-z errors and masking effects. We show that our bias measurement from the data is consistent with that expected from simulations. With the forthcoming full DES data set, we expect this method to provide additional constraints on the galaxy bias measurement from more traditional methods. Furthermore, in the process of our measurement, we build up a 3D mass map that allows further exploration of the dark matter distribution and its relation to galaxy evolution.

  16. Cosmology and galaxy formation

    International Nuclear Information System (INIS)

    Rees, M.J.

    1977-01-01

    Implications of the massive halos and ''missing mass'' for galaxy formation are addressed; it is suggested that this mass consists of ''Population III'' stars that formed before the galaxies did. 19 references

  17. THE ODD OFFSET BETWEEN THE GALACTIC DISK AND ITS BAR IN NGC 3906

    Energy Technology Data Exchange (ETDEWEB)

    Swardt, Bonita de [South African Astronomical Observatory, Observatory, 7935 Cape Town (South Africa); Sheth, Kartik; Kim, Taehyun; Muñoz-Mateos, Juan-Carlos [National Radio Astronomy Observatory/NAASC, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Stephen Pardy; Elena D’ Onghia; Eric Wilcots [Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States); Hinz, Joannah [MMTO, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Regan, Michael W. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Athanassoula, E.; Bosma, Albert [Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France); Buta, Ronald J. [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487 (United States); Cisternas, Mauricio; Erroz-Ferrer, Santiago [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Comerón, Sébastien [Division of Astronomy, Department of Physical Sciences, University of Oulu, Oulu, FI-90014 (Finland); Gadotti, Dimitri A. [European Southern Observatory, Casilla 19001, Santiago 19 (Chile); Paz, Armando Gil de [Departamento de Astrofísica, Universidad Complutense de Madrid, Madrid E-28040 (Spain); Jarrett, Thomas H. [Astronomy Department, University of Cape Town, Rondebosch 7701 (South Africa); Elmegreen, Bruce G. [IBM Research Division, T.J. Watson Research Center, Yorktown Hts., NY 10598 (United States); Ho, Luis C. [The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); and others

    2015-07-20

    We use mid-infrared 3.6 and 4.5 μm imaging of NGC 3906 from the Spitzer Survey of Stellar Structure in Galaxies (S{sup 4}G) to understand the nature of an unusual offset between its stellar bar and the photometric center of an otherwise regular, circular outer stellar disk. We measure an offset of ∼910 pc between the center of the stellar bar and photometric center of the stellar disk; the bar center coincides with the kinematic center of the disk determined from previous HI observations. Although the undisturbed shape of the disk suggests that NGC 3906 has not undergone a significant merger event in its recent history, the most plausible explanation for the observed offset is an interaction. Given the relatively isolated nature of NGC 3906 this interaction could be with dark matter substructure in the galaxy's halo or from a recent interaction with a fast moving neighbor that remains to be identified. Simulations aimed at reproducing the observed offset between the stellar bar/kinematic center of the system and the photometric center of the disk are necessary to confirm this hypothesis and constrain the interaction history of the galaxy.

  18. Sagittarius Dwarf Galaxy

    Science.gov (United States)

    Ibata, R.; Murdin, P.

    2000-11-01

    The Sagittarius DWARF GALAXY is the closest member of the Milky Way's entourage of satellite galaxies. Discovered by chance in 1994, its presence had previously been overlooked because it is largely hidden by the most crowded regions of our own Galaxy with which it is merging....

  19. Accretion by the Galaxy

    NARCIS (Netherlands)

    Binney, J.; Fraternali, F.; Reylé, C.; Robin, A.; Schultheis, M.

    Cosmology requires at least half of the baryons in the Universe to be in the intergalactic medium, much of which is believed to form hot coronae around galaxies. Star-forming galaxies must be accreting from their coronae. Hi observations of external galaxies show that they have Hi halos associated

  20. DO QUIESCENT AND ACTIVE GALAXIES HAVE DIFFERENT MBH-σ* RELATIONS?

    International Nuclear Information System (INIS)

    Woo, Jong-Hak; Park, Daeseong; Kang, Wol-Rang; Schulze, Andreas; Kim, Sang Chul; Riechers, Dominik A.

    2013-01-01

    To investigate the validity of the assumption that quiescent galaxies and active galaxies follow the same black hole mass (M BH )-stellar velocity dispersion (σ * ) relation, as required for the calibration of M BH estimators for broad line active galactic nuclei (AGNs), we determine and compare the M BH -σ * relations, respectively, for quiescent and active galaxies. For the quiescent galaxy sample, composed of 72 dynamical M BH measurements, we update σ * for 28 galaxies using homogeneous H-band measurements that are corrected for galaxy rotation. For active galaxies, we collect 25 reverberation-mapped AGNs and improve σ * measurement for two objects. Combining the two samples, we determine the virial factor f, first by scaling the active galaxy sample to the M BH -σ * relation of quiescent galaxies, and second by simultaneously fitting the quiescent and active galaxy samples, as f=5.1 -1.1 +1.5 and f=5.9 -1.5 +2.1 , respectively. The M BH -σ * relation of active galaxies appears to be shallower than that of quiescent galaxies. However, the discrepancy is caused by a difference in the accessible M BH distribution at given σ * , primarily due to the difficulty of measuring reliable stellar velocity dispersion for the host galaxies of luminous AGNs. Accounting for the selection effects, we find that active and quiescent galaxies are consistent with following intrinsically the same M BH -σ * relation

  1. Satellite dwarf galaxies in a hierarchical universe: the prevalence of dwarf-dwarf major mergers

    International Nuclear Information System (INIS)

    Deason, Alis; Wetzel, Andrew; Garrison-Kimmel, Shea

    2014-01-01

    Mergers are a common phenomenon in hierarchical structure formation, especially for massive galaxies and clusters, but their importance for dwarf galaxies in the Local Group remains poorly understood. We investigate the frequency of major mergers between dwarf galaxies in the Local Group using the ELVIS suite of cosmological zoom-in dissipationless simulations of Milky Way- and M31-like host halos. We find that ∼10% of satellite dwarf galaxies with M star > 10 6 M ☉ that are within the host virial radius experienced a major merger of stellar mass ratio closer than 0.1 since z = 1, with a lower fraction for lower mass dwarf galaxies. Recent merger remnants are biased toward larger radial distance and more recent virial infall times, because most recent mergers occurred shortly before crossing within the virial radius of the host halo. Satellite-satellite mergers also occur within the host halo after virial infall, catalyzed by the large fraction of dwarf galaxies that fell in as part of a group. The merger fraction doubles for dwarf galaxies outside of the host virial radius, so the most distant dwarf galaxies in the Local Group are the most likely to have experienced a recent major merger. We discuss the implications of these results on observable dwarf merger remnants, their star formation histories, the gas content of mergers, and massive black holes in dwarf galaxies.

  2. Evolution of stars and galaxies

    International Nuclear Information System (INIS)

    Baade, W.

    1975-01-01

    Transcriptions of recorded lectures given by the author have been edited into book form. Topics covered include: historical introduction, classification of galaxies; observation of galaxies; photography of galaxies; the andromeda nebula, spiral structure; dust and gas in galaxies; outline of stellar evolution; the distances to the galaxies; galactic clusters; stellar associations; the T Tauri stars; globular clusters: color-magnitude diagrams; spectra of population II stars; variable stars in globular clusters; elliptical galaxies; irregular galaxies and star formation; the magellanic clouds; the andromeda nebula, photometry; evolution of galaxies; the structure of the galaxy; the galactic nucleus; the galactic disk; and kinematics and evolution of the galaxy. 27 tables, 26 figures

  3. Triple bar, high efficiency mechanical sealer

    Science.gov (United States)

    Pak, Donald J.; Hawkins, Samantha A.; Young, John E.

    2013-03-19

    A clamp with a bottom clamp bar that has a planar upper surface is provided. The clamp may also include a top clamp bar connected to the bottom clamp bar, and a pressure distribution bar between the top clamp bar and the bottom clamp bar. The pressure distribution bar may have a planar lower surface in facing relation to the upper surface of the bottom clamp bar. An object is capable of being disposed in a clamping region between the upper surface and the lower surface. The width of the planar lower surface may be less than the width of the upper surface within the clamping region. Also, the pressure distribution bar may be capable of being urged away from the top clamp bar and towards the bottom clamp bar.

  4. USING COLORS TO IMPROVE PHOTOMETRIC METALLICITY ESTIMATES FOR GALAXIES

    International Nuclear Information System (INIS)

    Sanders, N. E.; Soderberg, A. M.; Levesque, E. M.

    2013-01-01

    There is a well known correlation between the mass and metallicity of star-forming galaxies. Because mass is correlated with luminosity, this relation is often exploited, when spectroscopy is not available, to estimate galaxy metallicities based on single band photometry. However, we show that galaxy color is typically more effective than luminosity as a predictor of metallicity. This is a consequence of the correlation between color and the galaxy mass-to-light ratio and the recently discovered correlation between star formation rate (SFR) and residuals from the mass-metallicity relation. Using Sloan Digital Sky Survey spectroscopy of ∼180, 000 nearby galaxies, we derive 'LZC relations', empirical relations between metallicity (in seven common strong line diagnostics), luminosity, and color (in 10 filter pairs and four methods of photometry). We show that these relations allow photometric metallicity estimates, based on luminosity and a single optical color, that are ∼50% more precise than those made based on luminosity alone; galaxy metallicity can be estimated to within ∼0.05-0.1 dex of the spectroscopically derived value depending on the diagnostic used. Including color information in photometric metallicity estimates also reduces systematic biases for populations skewed toward high or low SFR environments, as we illustrate using the host galaxy of the supernova SN 2010ay. This new tool will lend more statistical power to studies of galaxy populations, such as supernova and gamma-ray burst host environments, in ongoing and future wide-field imaging surveys

  5. Revisiting The First Galaxies: The Epoch of Population III Stars

    Science.gov (United States)

    Muratov, Alexander; Gnedin, O. Y.; Gnedin, N. Y.; Zemp, M. K.

    2013-01-01

    We study the formation of the first galaxies using new hydrodynamic cosmological simulations with the ART code. Our simulations feature a recently developed model for dust-based formation of molecular gas. Here, we develop and implement a new recipe for the formation of metal-free Pop III stars. We reach a spatial resolution of 2 pc at z=10 and resolve star-forming galaxies with the masses above 10^6 solar masses. We find the epoch during which Pop III stars dominate the energy and metal budget of the universe to be short-lived. While these stars seed their host galaxies with metals, they cannot drive significant outflows to enrich the IGM in our simulations. Feedback from pair instability supernovae causes Pop III star formation to self-terminate within their host galaxies, but is not strong enough to suppress star formation in external galaxies. Within any individual galaxy, Pop II stars overtake Pop III stars within ~50-150 Myr. A threshold of M = 3 * 10^6 solar masses separates galaxies that lose a significant fraction of their baryons due to Pop III feedback from those that do not. Understanding the nature of the transition between Pop III and Pop II star formation is of key importance for studying the dawn of galaxy formation.

  6. Stellar-to-halo mass relation of cluster galaxies

    International Nuclear Information System (INIS)

    Niemiec, Anna; Jullo, Eric; Limousin, Marceau; Giocoli, Carlo

    2017-01-01

    In the formation of galaxy groups and clusters, the dark matter haloes containing satellite galaxies are expected to be tidally stripped in gravitational interactions with the host. We use galaxy-galaxy weak lensing to measure the average mass of dark matter haloes of satellite galaxies as a function of projected distance to the centre of the host, since stripping is expected to be greater for satellites closer to the centre of the cluster. We further classify the satellites according to their stellar mass: assuming that the stellar component of the galaxy is less disrupted by tidal stripping, stellar mass can be used as a proxy of the infall mass. We study the stellar to halo mass relation of satellites as a function of the cluster-centric distance to measure tidal stripping. We use the shear catalogues of the DES science veri cation archive, the CFHTLenS and the CFHT Stripe 82 surveys, and we select satellites from the redMaPPer catalogue of clusters. For galaxies located in the outskirts of clusters, we nd a stellar to halo mass relation in good agreement with the theoretical expectations from Moster, Naab & White (2013) for central galaxies. In the centre of the cluster, we nd that this relation is shifted to smaller halo mass for a given stellar mass. We interpret this nding as further evidence for tidal stripping of dark matter haloes in high density environments.

  7. Galaxies Die in Groups: An IRAC Autopsy

    Science.gov (United States)

    Wilman, D. J.; Pierini, D.; Tyler, K.; McGee, S. L.; Oemler, A., Jr.; Morris, S. L.; Balogh, M. L.; Bower, R. G.; Mulchaey, J. S.

    2008-10-01

    The most massive galaxies in the Universe are also the oldest. To overturn this apparent contradiction with hierarchical growth models, we focus on the group-scale haloes which host most of these galaxies. Our z˜0.4 group sample is selected in redshift space from the CNOC2 redshift survey. A stellar mass selected M_{*} ≲ 2×10^{10}M_{⊙} sample is constructed using IRAC observations. A sensitive Mid InfraRed (MIR) IRAC colour is used to isolate passive galaxies. It produces a bimodal distribution, in which passive galaxies (highlighted by morphological early-types) define a tight MIR colour sequence (Infrared Passive Sequence, IPS). This is due to stellar atmospheric emission from old stellar populations. Significantly offset from the IPS are galaxies where reemission by dust boosts emission at λ_{obs}=8 micron. We term them InfraRed-Excess galaxies whether star formation and/or AGN activity are present. They include all known morphological late-types. The fraction of InfraRed Excess galaxies, f(IRE) drops with M_{*}, such that f(IRE)=0.5 at a ``crossover mass'' of M_{cr}˜ 1.3×10^{11}M_{⊙}. Within our optically-defined group sample there is a strong and consistent deficit in f(IRE) at all masses, but most clearly at M_{*} ≲ 10^{11}M_{⊙}. Suppression of star formation must mainly occur in groups, and the observed trend of f(IRE) with M_{*} can be explained if suppression of M_{*} ≲ 10^{11}M_{⊙} galaxies occurs primarily in the group environment.

  8. Selections from 2016: A Very Dark Galaxy

    Science.gov (United States)

    Kohler, Susanna

    2016-12-01

    Editors note:In these last two weeks of 2016, well be looking at a few selections that we havent yet discussed on AAS Nova from among the most-downloaded paperspublished in AAS journals this year. The usual posting schedule will resume after the AAS winter meeting.A High Stellar Velocity Dispersion and 100 Globular Clusters for the Ultra-Diffuse Galaxy Dragonfly 44Published August2016Main takeaway:Using the Keck Observatory and the Gemini North telescope in Hawaii, a team led by Pieter van Dokkum (Yale University) discovered the very dim galaxy Dragonfly 44, located in the Coma cluster. The team estimated the center of this galaxys disk to be a whopping 98% dark matter.Why its interesting:Dragonfly 44, though dim, was discovered to host around 100 globular clusters. Measuring the dynamics of these clusters allowed van Dokkum and collaborators to estimate the mass of Dragonfly 44: roughly a trillion times the mass of the Sun. This is similar to the mass of the Milky Way, and yet the Milky Way has over a hundred times more stars than this intriguing galaxy. Its very unexpected to find a galaxy this massive that has a dark-matter fraction this high.What we can learn from this:How do ultra-faint galaxies like these form? One theory is that theyre failed normal galaxies: they have the sizes, dark-matter content, and globular cluster systems of much more luminous galaxies, but they were prevented from building up a normal stellar population. So far, Dragonfly 44s properties seem consistent with this picture.CitationPieter van Dokkum et al 2016 ApJL 828 L6. doi:10.3847/2041-8205/828/1/L6

  9. Paired and interacting galaxies: Conference summary

    International Nuclear Information System (INIS)

    Norman, C.A.

    1990-01-01

    The author gives a summary of the conference proceedings. The conference began with the presentation of the basic data sets on pairs, groups, and interacting galaxies with the latter being further discussed with respect to both global properties and properties of the galactic nuclei. Then followed the theory, modelling and interpretation using analytic techniques, simulations and general modelling for spirals and ellipticals, starbursts and active galactic nuclei. Before the conference the author wrote down the three questions concerning pairs, groups and interacting galaxies that he hoped would be answered at the meeting: (1) How do they form, including the role of initial conditions, the importance of subclustering, the evolution of groups to compact groups, and the fate of compact groups; (2) How do they evolve, including issues such as relevant timescales, the role of halos and the problem of overmerging, the triggering and enhancement of star formation and activity in the galactic nuclei, and the relative importance of dwarf versus giant encounters; and (3) Are they important, including the frequency of pairs and interactions, whether merging and interactions are very important aspects of the life of a normal galaxy at formation, during its evolution, in forming bars, shells, rings, bulges, etc., and in the formation and evolution of active galaxies? Where possible he focuses on these three central issues in the summary

  10. Galaxy Zoo: Infrared and Optical Morphology

    Science.gov (United States)

    Carla Shanahan, Jesse; Lintott, Chris; Zoo, Galaxy

    2018-01-01

    We present the detailed, visual morphologies of approximately 60,000 galaxies observed by the UKIRT Infrared Deep Sky Survey and then classified by participants in the Galaxy Zoo project. Our sample is composed entirely of nearby objects with redshifts of z ≤ 0.3, which enables us to robustly analyze their morphological characteristics including smoothness, bulge properties, spiral structure, and evidence of bars or rings. The determination of these features is made via a consensus-based analysis of the Galaxy Zoo project data in which inconsistent and outlying classifications are statistically down-weighted. We then compare these classifications of infrared morphology to the objects’ optical classifications in the Galaxy Zoo 2 release (Willett et al. 2013). It is already known that morphology is an effective tool for uncovering a galaxy’s dynamical past, and previous studies have shown significant correlations with physical characteristics such as stellar mass distribution and star formation history. We show that majority of the sample has agreement or expected differences between the optical and infrared classifications, but also present a preliminary analysis of a subsample of objects with striking discrepancies.

  11. Star clusters in evolving galaxies

    Science.gov (United States)

    Renaud, Florent

    2018-04-01

    Their ubiquity and extreme densities make star clusters probes of prime importance of galaxy evolution. Old globular clusters keep imprints of the physical conditions of their assembly in the early Universe, and younger stellar objects, observationally resolved, tell us about the mechanisms at stake in their formation. Yet, we still do not understand the diversity involved: why is star cluster formation limited to 105M⊙ objects in the Milky Way, while some dwarf galaxies like NGC 1705 are able to produce clusters 10 times more massive? Why do dwarfs generally host a higher specific frequency of clusters than larger galaxies? How to connect the present-day, often resolved, stellar systems to the formation of globular clusters at high redshift? And how do these links depend on the galactic and cosmological environments of these clusters? In this review, I present recent advances on star cluster formation and evolution, in galactic and cosmological context. The emphasis is put on the theory, formation scenarios and the effects of the environment on the evolution of the global properties of clusters. A few open questions are identified.

  12. Galaxy Formation and Evolution

    CERN Document Server

    Spinrad, Hyron

    2005-01-01

    The evolution in the form and structure of galaxies which has taken place since the universe was in its infancy is one of the most closely studied by astrophysicists and cosmologists today. It has profound implications for our understanding of how the universe itself has evolved over the past 12 billion years or so. This book will discuss the evolution of galaxies in detail, emphasising the boundaries of our knowledge about the most distant galaxies, but demonstrating how it is possible to make important comparisons between nearby galaxies and the most distant current observed. The author will also review galaxy morphology and its likely (but as yet unproven) history.

  13. From nearby to distant galaxies: kinematical and dynamical studies

    Science.gov (United States)

    Epinat, Benoit

    2009-09-01

    Kinematical studies of low and high redshift galaxies enables to probe galaxy formation and evolution scenarios. Integral field spectroscopy is a powerful tool to study with accuracy nearby galaxies kinematics. Recent observations also gives a new 2D vision of high redshift galaxies kinematics. This work mostly relies on the kinematical sample of galaxies GHASP. This control sample, composed of 203 local spiral and irregular galaxies in low density environments observed with Fabry-Perot techniques in the Ha line (6563 A), is by now the largest sample of Fabry-Perot data. After a revue on Fabry-Perot interferometry and a presentation of new data reduction procedures, my implications on both 3D-NTT Fabry-Perot instrument and the wide field spectrograph project (WFSpec) for galaxy evolution study with the european ELT are developed. The second section is dedicated to GHASP data. This sample have been fully reduced and analysed using new methods. The kinematical analysis of 2D kinematical maps has been undertaken with the study of the dark matter distribution, the rotation curves shape, bar signatures and the ionized gas velocity dispersion. In a third section, this local reference sample is used as a zero point for high redshift galaxies kinematical studies. The GHASP sample is projected at high redshift (z=1.7) in order to disentangle evolution effects from distance biases in high redshift galaxies kinematical data observed with SINFONI, OSIRIS and GIRAFFE. The kinematical analysis of new SINFONI high redshift observations is also presented and high redshift data found in the literature are compared with GHASP projected sample, suggesting some evolution of the galaxy dynamical support within the ages.

  14. Black Hole Caught Zapping Galaxy into Existence?

    Science.gov (United States)

    2009-11-01

    Which come first, the supermassive black holes that frantically devour matter or the enormous galaxies where they reside? A brand new scenario has emerged from a recent set of outstanding observations of a black hole without a home: black holes may be "building" their own host galaxy. This could be the long-sought missing link to understanding why the masses of black holes are larger in galaxies that contain more stars. "The 'chicken and egg' question of whether a galaxy or its black hole comes first is one of the most debated subjects in astrophysics today," says lead author David Elbaz. "Our study suggests that supermassive black holes can trigger the formation of stars, thus 'building' their own host galaxies. This link could also explain why galaxies hosting larger black holes have more stars." To reach such an extraordinary conclusion, the team of astronomers conducted extensive observations of a peculiar object, the nearby quasar HE0450-2958 (see eso0523 for a previous study of this object), which is the only one for which a host galaxy has not yet been detected [1]. HE0450-2958 is located some 5 billion light-years away. Until now, it was speculated that the quasar's host galaxy was hidden behind large amounts of dust, and so the astronomers used a mid-infrared instrument on ESO's Very Large Telescope for the observations [2]. At such wavelengths, dust clouds shine very brightly, and are readily detected. "Observing at these wavelengths would allow us to trace dust that might hide the host galaxy," says Knud Jahnke, who led the observations performed at the VLT. "However, we did not find any. Instead we discovered that an apparently unrelated galaxy in the quasar's immediate neighbourhood is producing stars at a frantic rate." These observations have provided a surprising new take on the system. While no trace of stars is revealed around the black hole, its companion galaxy is extremely rich in bright and very young stars. It is forming stars at a rate

  15. SATELLITE DWARF GALAXIES IN A HIERARCHICAL UNIVERSE: THE PREVALENCE OF DWARF-DWARF MAJOR MERGERS

    OpenAIRE

    Deason, A; Wetzel, A; Garrison-Kimmel, S

    2014-01-01

    Mergers are a common phenomenon in hierarchical structure formation, especially for massive galaxies and clusters, but their importance for dwarf galaxies in the Local Group remains poorly understood. We investigate the frequency of major mergers between dwarf galaxies in the Local Group using the ELVIS suite of cosmological zoom-in dissipationless simulations of Milky Way- and M31-like host halos. We find that ~10% of satellite dwarf galaxies with M_star > 10^6 M_sun that are within the host...

  16. Chemical evolution of galaxies

    CERN Document Server

    Matteucci, Francesca

    2012-01-01

    The term “chemical evolution of galaxies” refers to the evolution of abundances of chemical species in galaxies, which is due to nuclear processes occurring in stars and to gas flows into and out of galaxies. This book deals with the chemical evolution of galaxies of all morphological types (ellipticals, spirals and irregulars) and stresses the importance of the star formation histories in determining the properties of stellar populations in different galaxies. The topic is approached in a didactical and logical manner via galaxy evolution models which are compared with observational results obtained in the last two decades: The reader is given an introduction to the concept of chemical abundances and learns about the main stellar populations in our Galaxy as well as about the classification of galaxy types and their main observables. In the core of the book, the construction and solution of chemical evolution models are discussed in detail, followed by descriptions and interpretations of observations of ...

  17. Glass Fiber Reinforced Polymer Dowel Bar Evaluation

    Science.gov (United States)

    2012-09-01

    Glass Fiber Reinforced Polymer (GFRP) dowel bars were installed on one new construction project and two dowel bar : retrofit projects to evaluate the performance of this type of dowel bar in comparison to steel dowel bars installed on the same : cont...

  18. All-sky catalog of local radio galaxies

    Science.gov (United States)

    van Velzen, S.; Falcke, H.

    2013-07-01

    The final episode in the history of black hole accretion and galaxy formation takes place in our cosmic backyard, the local universe. Within this volume must also reside the - until now unknown - sources of observed ultra-high energy cosmic rays (UHECRs). A thorough study of the local universe requires full-sky coverage to obtain a sizable sample and map the matter anisotropy. We recently constructed the first catalog of radio-emitting galaxies that meets this requirement. The sample contains all radio galaxies similar to Centaurus~A out to ~100 Mpc. Only 3% of the hosts of the powerful radio jets are classified as Spiral galaxies, while for non-radio galaxies of similar mass, this fraction is 34%. The energy injected by radio jets per unit volume indicates that Cen A-like radio galaxies have in principle sufficient power to accelerate cosmic rays to ultra-high energies. A significantly enhanced clustering of radio-loud galaxies compared to normal galaxies of the same luminosity is observed. This indicates a causal relation between galaxy environment and jet power, independent of black hole mass.

  19. RADIO GALAXY FEEDBACK IN X-RAY-SELECTED GROUPS FROM COSMOS: THE EFFECT ON THE INTRACLUSTER MEDIUM

    International Nuclear Information System (INIS)

    Giodini, S.; Finoguenov, A.; Boehringer, H.; Pierini, D.; Smolcic, V.; Massey, R.; BIrzan, L.; Zamorani, G.; Oklopcic, A.; Pratt, G. W.; Schinnerer, E.; Koekemoer, A. M.; Salvato, M.; Sanders, D. B.; Kartaltepe, J. S.; Thompson, D.

    2010-01-01

    We quantify the importance of the mechanical energy released by radio galaxies inside galaxy groups. We use scaling relations to estimate the mechanical energy released by 16 radio-active galactic nuclei located inside X-ray-detected galaxy groups in the COSMOS field. By comparing this energy output to the host groups' gravitational binding energy, we find that radio galaxies produce sufficient energy to unbind a significant fraction of the intragroup medium. This unbinding effect is negligible in massive galaxy clusters with deeper potential wells. Our results correctly reproduce the breaking of self-similarity observed in the scaling relation between entropy and temperature for galaxy groups.

  20. New Methods for Tracking Galaxy and Black Hole Evolution Using Post-Starburst Galaxies

    Science.gov (United States)

    French, Katheryn Decker

    2017-08-01

    Galaxies in transition from star-forming to quiescence are a natural laboratory for exploring the processes responsible for this evolution. Using a sample of post-starburst galaxies identified to have recently experienced a recent burst of star formation that has now ended, I explore both the fate of the molecular gas that drives star formation and the increased rate of stars disrupted by the central supermassive black hole. Chapter 1 provides an introduction to galaxy evolution through the post-starburst phase and to tidal disruption events, which surprisingly favor post-starburst galaxy hosts. In Chapter 2, I present a survey of the molecular gas properties of 32 post-starburst galaxies traced by CO (1-0) and CO (2-1). In order to accurately put galaxies on an evolutionary sequence, we must select likely progenitors and descendants. We do this by identifying galaxies with similar starburst properties, such as the amount of mass produced in the burst and the burst duration. In Chapter 3, I describe a method to determine the starburst properties and the time elapsed since the starburst ended, and discuss trends in the molecular gas properties of these galaxies with time. In Chapter 4, I present the results of followup observations with ALMA of HCN (1-0) and HCO+ (1-0) in two post-starburst galaxies. CO (1-0) is detected in over half (17/32) the post-starburst sample and the molecular gas mass traced by CO declines on ˜100 Myr timescales after the starburst has ended. HCN (1-0) is not detected in either galaxy targeted, indicating the post-starbursts are now quiescent because of a lack of the denser molecular gas traced by HCN. In Chapter 5 I quantify the increase in TDE rate in quiescent galaxies with strong Balmer absorption to be 30 - 200x higher than in normal galaxies. Using the stellar population fitting method from Chapter 3, I examine possible reasons for the increased TDE rate in post-starburst galaxies in Chapter 6. The TDE rate could be boosted due to a

  1. ON THE RATES OF TYPE Ia SUPERNOVAE IN DWARF AND GIANT HOSTS WITH ROTSE-IIIb

    Energy Technology Data Exchange (ETDEWEB)

    Quimby, Robert M. [Kavli IPMU, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8583 (Japan); Yuan Fang [Research School of Astronomy and Astrophysics, Australian National University, Weston Creek, ACT 2611 (Australia); Akerlof, Carl [Physics Department, University of Michigan, Ann Arbor, MI 48109 (United States); Wheeler, J. Craig [Department of Astronomy, McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Warren, Michael S. [Theoretical Division, Mail Stop B227, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2012-12-01

    We present a sample of 23 spectroscopically confirmed Type Ia supernovae (SNe Ia) that were discovered in the background of galaxy clusters targeted by ROTSE-IIIb and use up to 18 of these to determine the local (z-bar 0.05) volumetric rate. Since our survey is flux limited and thus biased against fainter objects, the pseudo-absolute magnitude distribution (pAMD) of SNe Ia in a given volume is an important concern, especially the relative frequency of high- to low-luminosity SNe Ia. We find that the pAMD derived from the volume-limited Lick Observatory Supernova Search (LOSS) sample is incompatible with the distribution of SNe Ia in a volume-limited (z < 0.12) sub-sample of the Sloan Digital Sky Survey II (SDSS-II). The LOSS sample requires far more low-luminosity SNe Ia than the SDSS-II can accommodate. Even though LOSS and SDSS-II have sampled different SNe Ia populations, their volumetric rates are surprisingly similar. Using the same model pAMD adopted in the SDSS-II SNe Ia rate calculation and excluding two high-luminosity SNe Ia from our sample, we derive a rate that is marginally higher than previous low-redshift determinations. With our full sample and the LOSS pAMD, our rate is more than double the canonical value. We also find that 5 of our 18 SNe Ia are hosted by very low luminosity (M{sub B} > -16) galaxies, whereas only 1 out of 79 nearby SDSS-II SNe Ia have such faint hosts. It is possible that previous works have undercounted either low-luminosity SNe Ia, SNe Ia in low-luminosity hosts, or peculiar SNe Ia (sometimes explicitly), and the total SNe Ia rate may be higher than the canonical value.

  2. Galaxy Zoo: dust in spiral galaxies star

    OpenAIRE

    Masters, Karen L.; Nichol, Robert; Bamford, Steven; Mosleh, Moein; Lintott, Chris J.; Andreescu, Dan; Edmondson, Edward M.; Keel, William C.; Murray, Phil; Raddick, M. Jordan; Schawinski, Kevin; Slosar, Anze; Szalay, Alexander S.; Thomas, Daniel; Vandenberg, Jan

    2010-01-01

    We investigate the effect of dust on spiral galaxies by measuring the inclination dependence of optical colours for 24 276 well-resolved Sloan Digital Sky Survey (SDSS) galaxies visually classified via the Galaxy Zoo project. We find clear trends of reddening with inclination which imply a total extinction from face-on to edge-on of 0.7, 0.6, 0.5 and 0.4 mag for the ugri passbands (estimating 0.3 mag of extinction in z band). We split the sample into ‘bulgy’ (early-type) and ‘discy’ (late-typ...

  3. Measurement of the asymmetry parameter for the decay $\\bar\\Lambda \\to \\bar p\\pi^+$

    OpenAIRE

    BES collaboration

    2009-01-01

    Based on a sample of $58\\times10^6J/\\psi$ decays collected with the BESII detector at the BEPC, the $\\bar\\Lambda$ decay parameter $\\alpha_{\\bar\\Lambda}$ for $\\bar\\Lambda\\to \\bar p \\pi^+$ is measured using about 9000 $J/\\psi\\to\\Lambda\\bar\\Lambda\\to p \\bar p \\pi^+\\pi^-$ decays. A fit to the joint angular distributions yields $\\alpha_{\\bar\\Lambda}(\\bar\\Lambda\\to \\bar p\\pi^+)=-0.755\\pm0.083\\pm0.063$, where the first error is statistical, and the second systematic.

  4. The Evolution of Galaxies Through the Spatial Distribution of Their Globular Clusters: the Brightest Galaxies in Fornax

    Science.gov (United States)

    Zegeye, David W.

    2018-01-01

    We present a study of the evolution of the 10 brightest galaxies in the Fornax Cluster, as reconstructed through their Globular Cluster (GC) populations. GCs can be characterized by their projected two-dimensional (2D) spatial distribution. Over- or under-densities in the GC distribution, can be linked to events in the host galaxy assembly history, and used to constrain the properties of their progenitors. With HST/ACS imaging, we identified significant structures in the GC distribution of the 10 galaxies investigated, with some of the galaxies possessing structures with >10-sigma significance. GC over-densities have been found within the galaxies, with significant differences between the red and blue GC population. For elongated galaxies, structures are preferentially to be aligned along the major axis. Fornax Cluster galaxies appear to be more dynamically relaxed than the Virgo Cluster galaxies previously investigated with the same methodology by D'Abrusco et al. (2016). However, from these observations, the evident imprints left in the spatial distribution of GCs in these galaxies suggest a similarly intense history of interactions.The SAO REU program is funded by the National Science Foundation REU and Department of Defense ASSURE programs under NSF Grant AST-1659473, and by the Smithsonian Institution.

  5. ECO and RESOLVE: Galaxy Disk Growth in Environmental Context

    Science.gov (United States)

    Moffett, Amanda J.; Kannappan, Sheila J.; Berlind, Andreas A.; Eckert, Kathleen D.; Stark, David V.; Hendel, David; Norris, Mark A.; Grogin, Norman A.

    2015-10-01

    We study the relationships between galaxy environments and galaxy properties related to disk (re)growth, considering two highly complete samples that are approximately baryonic mass limited into the high-mass dwarf galaxy regime, the Environmental COntext catalog (data release herein) and the B-semester region of the REsolved Spectroscopy Of a Local VolumE survey. We quantify galaxy environments using both group identification and smoothed galaxy density field methods. We use by-eye and quantitative morphological classifications plus atomic gas content measurements and estimates. We find that blue early-type (E/S0) galaxies, gas-dominated galaxies, and UV-bright disk host galaxies all become distinctly more common below group halo mass ˜ {10}11.5 {M}⊙ , implying that this low group halo mass regime may be a preferred regime for significant disk growth activity. We also find that blue early-type and blue late-type galaxies inhabit environments of similar group halo mass at fixed baryonic mass, consistent with a scenario in which blue early-types can regrow late-type disks. In fact, we find that the only significant difference in the typical group halo mass inhabited by different galaxy classes is for satellite galaxies with different colors, where at fixed baryonic mass red early- and late-types have higher typical group halo masses than blue early- and late-types. More generally, we argue that the traditional morphology-environment relation (i.e., that denser environments tend to have more early-types) can be largely attributed to the morphology-galaxy mass relation for centrals and the color-environment relation for satellites.

  6. Early-type galaxies with extended HI reservoirs

    Science.gov (United States)

    Donovan Meyer, Jennifer

    2018-01-01

    I will present observations of NGC 404 and ESO 381-47, both early-type galaxies known for hosting extended HI rings and recent star formation in their outskirts. Thanks to the Green Bank Telescope, an instrument uniquely suited to observing diffuse, low column density HI around nearby galaxies, we report new measurements of the extent of the disk around NGC 404 as well as the presence of a large, coherent HI filament which appears to be accreting onto the ring surrounding the galaxy. We compare the environments of the two systems and interpret the potential utility of such gas-bearing field early-type galaxies as tracers of galaxy accretion and growth.

  7. Alignment between galaxies and large-scale structure

    International Nuclear Information System (INIS)

    Faltenbacher, A.; Li Cheng; White, Simon D. M.; Jing, Yi-Peng; Mao Shude; Wang Jie

    2009-01-01

    Based on the Sloan Digital Sky Survey DR6 (SDSS) and the Millennium Simulation (MS), we investigate the alignment between galaxies and large-scale structure. For this purpose, we develop two new statistical tools, namely the alignment correlation function and the cos(2θ)-statistic. The former is a two-dimensional extension of the traditional two-point correlation function and the latter is related to the ellipticity correlation function used for cosmic shear measurements. Both are based on the cross correlation between a sample of galaxies with orientations and a reference sample which represents the large-scale structure. We apply the new statistics to the SDSS galaxy catalog. The alignment correlation function reveals an overabundance of reference galaxies along the major axes of red, luminous (L ∼ * ) galaxies out to projected separations of 60 h- 1 Mpc. The signal increases with central galaxy luminosity. No alignment signal is detected for blue galaxies. The cos(2θ)-statistic yields very similar results. Starting from a MS semi-analytic galaxy catalog, we assign an orientation to each red, luminous and central galaxy, based on that of the central region of the host halo (with size similar to that of the stellar galaxy). As an alternative, we use the orientation of the host halo itself. We find a mean projected misalignment between a halo and its central region of ∼ 25 deg. The misalignment decreases slightly with increasing luminosity of the central galaxy. Using the orientations and luminosities of the semi-analytic galaxies, we repeat our alignment analysis on mock surveys of the MS. Agreement with the SDSS results is good if the central orientations are used. Predictions using the halo orientations as proxies for central galaxy orientations overestimate the observed alignment by more than a factor of 2. Finally, the large volume of the MS allows us to generate a two-dimensional map of the alignment correlation function, which shows the reference

  8. Dwarf elliptical galaxies with kinematically decoupled cores

    Science.gov (United States)

    De Rijcke, S.; Dejonghe, H.; Zeilinger, W. W.; Hau, G. K. T.

    2004-10-01

    We present, for the first time, photometric and kinematical evidence, obtained with FORS2 on the VLT, for the existence of kinematically decoupled cores (KDCs) in two dwarf elliptical galaxies; FS76 in the NGC 5044 group and FS373 in the NGC 3258 group. Both kinematically peculiar subcomponents rotate in the same sense as the main body of their host galaxy but betray their presence by a pronounced bump in the rotation velocity profiles at a radius of about 1''. The KDC in FS76 rotates at 10 ± 3 km s-1, with the host galaxy rotating at 15 ± 6 km s-1; the KDC in FS373 has a rotation velocity of 6 ± 2 km s-1 while the galaxy itself rotates at 20 ± 5 km s-1. FS373 has a very complex rotation velocity profile with the velocity changing sign at 1.5 Re. The velocity and velocity dispersion profiles of FS76 are asymmetric at larger radii. This could be caused by a past gravitational interaction with the giant elliptical NGC 5044, which is at a projected distance of 50 kpc. We argue that these decoupled cores are most likely not produced by mergers in a group or cluster environment because of the prohibitively large relative velocities. A plausible alternative is offered by flyby interactions between a dwarf elliptical or its disky progenitor and a massive galaxy. The tidal forces during an interaction at the relative velocities and impact parameters typical for a group environment exert a torque on the dwarf galaxy that, according to analytical estimates, transfers enough angular momentum to its stellar envelope to explain the observed peculiar kinematics.

  9. Suppression of star formation in early-type galaxies by feedback from supermassive black holes.

    Science.gov (United States)

    Schawinski, Kevin; Khochfar, Sadegh; Kaviraj, Sugata; Yi, Sukyoung K; Boselli, Alessandro; Barlow, Tom; Conrow, Tim; Forster, Karl; Friedman, Peter G; Martin, D Chris; Morrissey, Patrick; Neff, Susan; Schiminovich, David; Seibert, Mark; Small, Todd; Wyder, Ted K; Bianchi, Luciana; Donas, Jose; Heckman, Tim; Lee, Young-Wook; Madore, Barry; Milliard, Bruno; Rich, R Michael; Szalay, Alex

    2006-08-24

    Detailed high-resolution observations of the innermost regions of nearby galaxies have revealed the presence of supermassive black holes. These black holes may interact with their host galaxies by means of 'feedback' in the form of energy and material jets; this feedback affects the evolution of the host and gives rise to observed relations between the black hole and the host. Here we report observations of the ultraviolet emissions of massive early-type galaxies. We derive an empirical relation for a critical black-hole mass (as a function of velocity dispersion) above which the outflows from these black holes suppress star formation in their hosts by heating and expelling all available cold gas. Supermassive black holes are negligible in mass compared to their hosts but nevertheless seem to play a critical role in the star formation history of galaxies.

  10. Isolated galaxies, pairs, and groups of galaxies

    International Nuclear Information System (INIS)

    Kuneva, I.; Kalinkov, M.

    1990-01-01

    The authors searched for isolated galaxies, pairs and groups of galaxies in the CfA survey (Huchra et al. 1983). It was assumed that the distances to galaxies are given by R = V/H sub o, where H sub o = 100 km s(exp -1) Mpc(exp -1) and R greater than 6 Mpc. The searching procedure is close to those, applied to find superclusters of galaxies (Kalinkov and Kuneva 1985, 1986). A sphere with fixed radius r (asterisk) is described around each galaxy. The mean spatial density in the sphere is m. Let G 1 be any galaxy and G 2 be its nearest neighbor at a distance R 2 . If R sub 2 exceeds the 95 percent quintile in the distribution of the distances of the second neighbors, then G 1 is an isolated galaxy. Let the midpoint of G 1 and G 2 be O 2 and r 2 =R 2 2. For the volume V 2 , defined with the radius r 2 , the density D 2 less than k mu, the galaxy G 2 is a single one and the procedure for searching for pairs and groups, beginning with this object is over and we have to pass to another object. Here the authors present the groups - isolated and nonisolated - with n greater than 3, found in the CfA survey in the Northern galactic hemisphere. The parameters used are k = 10 and r (asterisk) = 5 Mpc. Table 1 contains: (1) the group number, (2) the galaxy, nearest to the multiplet center, (3) multiplicity n, (4) the brightest galaxy if it is not listed in (2); (5) and (6) are R.A. and Dec. (1950), (7) - mean distance D in Mpc. Further there are the mean density rho (8) of the multiplet (galaxies Mpc (exp -3)), (9) the density rho (asterisk) for r (asterisk) = 5 Mpc and (10) the density rho sub g for the group with its nearest neighbor. The parenthesized digits for densities in the last three columns are powers of ten

  11. A UNIFIED FRAMEWORK FOR THE ORBITAL STRUCTURE OF BARS AND TRIAXIAL ELLIPSOIDS

    Energy Technology Data Exchange (ETDEWEB)

    Valluri, Monica; Abbott, Caleb [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Shen, Juntai [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Debattista, Victor P., E-mail: mvalluri@umich.edu, E-mail: calebga@umich.edu, E-mail: jshen@shao.ac.cn, E-mail: vpdebattista@uclan.ac.uk [Jeremiah Horrocks Institute, University of Central Lancashire, Preston, PR1 2HE (United Kingdom)

    2016-02-20

    We examine a large random sample of orbits in two self-consistent simulations of N-body bars. Orbits in these bars are classified both visually and with a new automated orbit classification method based on frequency analysis. The well-known prograde x1 orbit family originates from the same parent orbit as the box orbits in stationary and rotating triaxial ellipsoids. However, only a small fraction of bar orbits (∼4%) have predominately prograde motion like their periodic parent orbit. Most bar orbits arising from the x1 orbit have little net angular momentum in the bar frame, making them equivalent to box orbits in rotating triaxial potentials. In these simulations a small fraction of bar orbits (∼7%) are long-axis tubes that behave exactly like those in triaxial ellipsoids: they are tipped about the intermediate axis owing to the Coriolis force, with the sense of tipping determined by the sign of their angular momentum about the long axis. No orbits parented by prograde periodic x2 orbits are found in the pure bar model, but a tiny population (∼2%) of short-axis tube orbits parented by retrograde x4 orbits are found. When a central point mass representing a supermassive black hole (SMBH) is grown adiabatically at the center of the bar, those orbits that lie in the immediate vicinity of the SMBH are transformed into precessing Keplerian orbits that belong to the same major families (short-axis tubes, long-axis tubes and boxes) occupying the bar at larger radii. During the growth of an SMBH, the inflow of mass and outward transport of angular momentum transform some x1 and long-axis tube orbits into prograde short-axis tubes. This study has important implications for future attempts to constrain the masses of SMBHs in barred galaxies using orbit-based methods like the Schwarzschild orbit superposition scheme and for understanding the observed features in barred galaxies.

  12. The Merger-Free Growth of Galaxies and Supermassive Black Holes

    Science.gov (United States)

    Simmons, Brooke; Smethurst, Rebecca; Lintott, Chris; Martin, Garreth; Kaviraj, Sugata; Devriendt, Julien; Galaxy Zoo Team

    2018-01-01

    There is now clear evidence that the merger-driven pathway to black hole and galaxy growth is only half the story. Merger-free evolution contributes roughly equally to the overall growth of black holes in the Universe and is also responsible for a significant amount of galaxy growth over cosmic time. A recent study examining the growth of black holes in unambiguously disk-dominated galaxies shows these black holes reach quasar-like luminosities and black hole masses typical of those hosted in bulge-dominated and elliptical galaxies with major mergers in their evolutionary histories. However, while there appears to be no correlation between the size of the black hole and upper limits on the host galaxy bulges, the fitted correlation between black hole mass and total galaxy stellar mass in these merger-free systems is fully consistent with the canonical relationship based on merger-driven systems. There is further evidence via comparison between observed populations and cosmological simulations confirming that bulgeless systems are generally consistent with having merger-free histories. If bulgeless and disk-dominated galaxies are indeed signatures of systems with no violent mergers in their formation histories, the same correlation between black hole and galaxy in these systems versus that seen in elliptical galaxy samples indicates the black hole-galaxy connection must originate with a process more fundamental than the dynamical configuration of a galaxy's stars.

  13. Galaxy formation and evolution

    CERN Document Server

    Mo, Houjun; White, Simon

    2010-01-01

    The rapidly expanding field of galaxy formation lies at the interface between astronomy, particle physics, and cosmology. Covering diverse topics from these disciplines, all of which are needed to understand how galaxies form and evolve, this book is ideal for researchers entering the field. Individual chapters explore the evolution of the Universe as a whole and its particle and radiation content; linear and nonlinear growth of cosmic structure; processes affecting the gaseous and dark matter components of galaxies and their stellar populations; the formation of spiral and elliptical galaxies; central supermassive black holes and the activity associated with them; galaxy interactions; and the intergalactic medium. Emphasizing both observational and theoretical aspects, this book provides a coherent introduction for astronomers, cosmologists, and astroparticle physicists to the broad range of science underlying the formation and evolution of galaxies.

  14. Diversity among galaxy clusters

    International Nuclear Information System (INIS)

    Struble, M.F.; Rood, H.J.

    1988-01-01

    The classification of galaxy clusters is discussed. Consideration is given to the classification scheme of Abell (1950's), Zwicky (1950's), Morgan, Matthews, and Schmidt (1964), and Morgan-Bautz (1970). Galaxies can be classified based on morphology, chemical composition, spatial distribution, and motion. The correlation between a galaxy's environment and morphology is examined. The classification scheme of Rood-Sastry (1971), which is based on clusters's morphology and galaxy population, is described. The six types of clusters they define include: (1) a cD-cluster dominated by a single large galaxy, (2) a cluster dominated by a binary, (3) a core-halo cluster, (4) a cluster dominated by several bright galaxies, (5) a cluster appearing flattened, and (6) an irregularly shaped cluster. Attention is also given to the evolution of cluster structures, which is related to initial density and cluster motion

  15. Signaling behind bars: a role for bar domains

    NARCIS (Netherlands)

    de Kreuk, B.J.

    2012-01-01

    In this thesis we describe several novel components of growth factor receptor and RhoGTPase activation and signaling. We have demonstrated that the F-BAR protein PACSIN2 is an important regulator of Rac1 output and, as a consequence, cell spreading and migration. This study further established the

  16. Cosmic axion background propagation in galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Day, Francesca V., E-mail: francesca.day@physics.ox.ac.uk

    2016-02-10

    Many extensions of the Standard Model include axions or axion-like particles (ALPs). Here we study ALP to photon conversion in the magnetic field of the Milky Way and starburst galaxies. By modelling the effects of the coherent and random magnetic fields, the warm ionized medium and the warm neutral medium on the conversion process, we simulate maps of the conversion probability across the sky for a range of ALP energies. In particular, we consider a diffuse cosmic ALP background (CAB) analogous to the CMB, whose existence is suggested by string models of inflation. ALP–photon conversion of a CAB in the magnetic fields of galaxy clusters has been proposed as an explanation of the cluster soft X-ray excess. We therefore study the phenomenology and expected photon signal of CAB propagation in the Milky Way. We find that, for the CAB parameters required to explain the cluster soft X-ray excess, the photon flux from ALP–photon conversion in the Milky Way would be unobservably small. The ALP–photon conversion probability in galaxy clusters is 3 orders of magnitude higher than that in the Milky Way. Furthermore, the morphology of the unresolved cosmic X-ray background is incompatible with a significant component from ALP–photon conversion. We also consider ALP–photon conversion in starburst galaxies, which host much higher magnetic fields. By considering the clumpy structure of the galactic plasma, we find that conversion probabilities comparable to those in clusters may be possible in starburst galaxies.

  17. A vast, thin plane of corotating dwarf galaxies orbiting the Andromeda galaxy.

    Science.gov (United States)

    Ibata, Rodrigo A; Lewis, Geraint F; Conn, Anthony R; Irwin, Michael J; McConnachie, Alan W; Chapman, Scott C; Collins, Michelle L; Fardal, Mark; Ferguson, Annette M N; Ibata, Neil G; Mackey, A Dougal; Martin, Nicolas F; Navarro, Julio; Rich, R Michael; Valls-Gabaud, David; Widrow, Lawrence M

    2013-01-03

    Dwarf satellite galaxies are thought to be the remnants of the population of primordial structures that coalesced to form giant galaxies like the Milky Way. It has previously been suspected that dwarf galaxies may not be isotropically distributed around our Galaxy, because several are correlated with streams of H I emission, and may form coplanar groups. These suspicions are supported by recent analyses. It has been claimed that the apparently planar distribution of satellites is not predicted within standard cosmology, and cannot simply represent a memory of past coherent accretion. However, other studies dispute this conclusion. Here we report the existence of a planar subgroup of satellites in the Andromeda galaxy (M 31), comprising about half of the population. The structure is at least 400 kiloparsecs in diameter, but also extremely thin, with a perpendicular scatter of less than 14.1 kiloparsecs. Radial velocity measurements reveal that the satellites in this structure have the same sense of rotation about their host. This shows conclusively that substantial numbers of dwarf satellite galaxies share the same dynamical orbital properties and direction of angular momentum. Intriguingly, the plane we identify is approximately aligned with the pole of the Milky Way's disk and with the vector between the Milky Way and Andromeda.

  18. (Almost) Dark Galaxies in the ALFALFA Survey: HI-bearing Ultra-Diffuse Galaxies, and Beyond

    Science.gov (United States)

    Leisman, Luke; Haynes, Martha P.; Giovanelli, Riccardo; ALFALFA Almost Darks Team

    2017-01-01

    Scaling relations between HI and stars in galaxies suggest strong ties between their atomic gas content and star formation laws. The Arecibo Legacy Fast ALFA (ALFALFA) blind extragalactic HI survey is well positioned to locate very low surface brightness sources that lie off these relations, the most extreme of which may fall below optical detection limits. Thus, the ALFALFA (Almost) Darks Project has been investigating extreme outliers from these relations by studying the ~1% of ALFALFA sources without apparent stellar counterparts in major optical surveys. We have obtained deep HI and optical imaging of 25 of these candidate "dark" sources. We find that most "dark" sources are not extreme "(almost) dark" galaxies. A few are rare OH Megamasers, redshifted into the ALFALFA bandpass, and many are part of large galactic plumes, stretching as far as 600 kpc from their host galaxy. However, a small handful of sources appear to be galaxies with extreme stellar systems. We find multiple systems with HI mass to stellar mass ratios an order of magnitude larger than typical gas rich dwarfs. Further, we find an isolated population of HI-bearing "ultra diffuse" galaxies (UDGs), with stellar masses of dwarfs, but HI and optical radii of L* galaxies. We suggest that these sources may be related to recently reported gas poor, quiescent UDGs.

  19. An over-massive black hole in the compact lenticular galaxy NGC 1277.

    Science.gov (United States)

    van den Bosch, Remco C E; Gebhardt, Karl; Gültekin, Kayhan; van de Ven, Glenn; van der Wel, Arjen; Walsh, Jonelle L

    2012-11-29

    Most massive galaxies have supermassive black holes at their centres, and the masses of the black holes are believed to correlate with properties of the host-galaxy bulge component. Several explanations have been proposed for the existence of these locally established empirical relationships, including the non-causal, statistical process of galaxy-galaxy merging, direct feedback between the black hole and its host galaxy, and galaxy-galaxy merging and the subsequent violent relaxation and dissipation. The empirical scaling relations are therefore important for distinguishing between various theoretical models of galaxy evolution, and they furthermore form the basis for all black-hole mass measurements at large distances. Observations have shown that the mass of the black hole is typically 0.1 per cent of the mass of the stellar bulge of the galaxy. Until now, the galaxy with the largest known fraction of its mass in its central black hole (11 per cent) was the small galaxy NGC 4486B. Here we report observations of the stellar kinematics of NGC 1277, which is a compact, lenticular galaxy with a mass of 1.2 × 10(11) solar masses. From the data, we determine that the mass of the central black hole is 1.7 × 10(10) solar masses, or 59 per cent of its bulge mass. We also show observations of five other compact galaxies that have properties similar to NGC 1277 and therefore may also contain over-massive black holes. It is not yet known if these galaxies represent a tail of a distribution, or if disk-dominated galaxies fail to follow the usual black-hole mass scaling relations.

  20. The origin of galaxies

    International Nuclear Information System (INIS)

    Carr, B.J.

    1982-01-01

    The existence of galaxies implies that the early Universe must have contained initial density fluctuations. Overdense regions would then expand more slowly than the background and eventually - providing the fluctuations were not damped out first - they would stop expanding altogether and collapse to form bound objects. To understand how galaxies form we therefore need to know: how the initial density fluctuations arise, under what circumstances they evolve into bound objects, and how the bound objects develop the observed characteristics of galaxies. (author)

  1. HI in elliptical galaxies

    OpenAIRE

    Sadler, Elaine M.; Oosterloo, Tom; Morganti, Raffaella

    2002-01-01

    Neutral hydrogen is an important component of the interstellar medium in elliptical galaxies as well as a potentially valuable mass tracer. Until recently, HI surveys of early-type galaxies have been sparse and inhomogeneous but this has changed with the advent of the HI Parkes All-Sky Survey (HIPASS; Barnes et al. 2001). We discuss HIPASS observations of a sample of ~2500 nearby E/S0 galaxies, as well as detailed HI imaging of a range of individual objects.

  2. Galaxy evolution. Galactic paleontology.

    Science.gov (United States)

    Tolstoy, Eline

    2011-07-08

    Individual low-mass stars have very long lives, comparable to the age of the universe, and can thus be used to probe ancient star formation. At present, such stars can be identified and studied only in the Milky Way and in the very closest of our neighboring galaxies, which are predominantly small dwarf galaxies. These nearby ancient stars are a fossil record that can provide detailed information about the physical processes that dominated the epoch of galaxy formation and subsequent evolution.

  3. Amazing Andromeda Galaxy

    Science.gov (United States)

    2006-01-01

    The many 'personalities' of our great galactic neighbor, the Andromeda galaxy, are exposed in this new composite image from NASA's Galaxy Evolution Explorer and the Spitzer Space Telescope. The wide, ultraviolet eyes of Galaxy Evolution Explorer reveal Andromeda's 'fiery' nature -- hotter regions brimming with young and old stars. In contrast, Spitzer's super-sensitive infrared eyes show Andromeda's relatively 'cool' side, which includes embryonic stars hidden in their dusty cocoons. Galaxy Evolution Explorer detected young, hot, high-mass stars, which are represented in blue, while populations of relatively older stars are shown as green dots. The bright yellow spot at the galaxy's center depicts a particularly dense population of old stars. Swaths of red in the galaxy's disk indicate areas where Spitzer found cool, dusty regions where stars are forming. These stars are still shrouded by the cosmic clouds of dust and gas that collapsed to form them. Together, Galaxy Evolution Explorer and Spitzer complete the picture of Andromeda's swirling spiral arms. Hints of pinkish purple depict regions where the galaxy's populations of hot, high-mass stars and cooler, dust-enshrouded stars co-exist. Located 2.5 million light-years away, the Andromeda is our largest nearby galactic neighbor. The galaxy's entire disk spans about 260,000 light-years, which means that a light beam would take 260,000 years to travel from one end of the galaxy to the other. By comparison, our Milky Way galaxy's disk is about 100,000 light-years across. This image is a false color composite comprised of data from Galaxy Evolution Explorer's far-ultraviolet detector (blue), near-ultraviolet detector (green), and Spitzer's multiband imaging photometer at 24 microns (red).

  4. Galaxies: The Long Wavelength View

    National Research Council Canada - National Science Library

    Fischer, J

    2000-01-01

    ... (more than 2 orders of magnitude) in the [C II]/FIR ratios in galaxies extending from blue compact dwarfs, to normal and starburst galaxies, down to elliptical and ultraluminous galaxies (ULICs...

  5. Galaxy Zoo: dust in spiral galaxies

    Science.gov (United States)

    Masters, Karen L.; Nichol, Robert; Bamford, Steven; Mosleh, Moein; Lintott, Chris J.; Andreescu, Dan; Edmondson, Edward M.; Keel, William C.; Murray, Phil; Raddick, M. Jordan; Schawinski, Kevin; Slosar, Anže; Szalay, Alexander S.; Thomas, Daniel; Vandenberg, Jan

    2010-05-01

    We investigate the effect of dust on spiral galaxies by measuring the inclination dependence of optical colours for 24276 well-resolved Sloan Digital Sky Survey (SDSS) galaxies visually classified via the Galaxy Zoo project. We find clear trends of reddening with inclination which imply a total extinction from face-on to edge-on of 0.7, 0.6, 0.5 and 0.4mag for the ugri passbands (estimating 0.3mag of extinction in z band). We split the sample into `bulgy' (early-type) and `discy' (late-type) spirals using the SDSS fracdeV (or fDeV) parameter and show that the average face-on colour of `bulgy' spirals is redder than the average edge-on colour of `discy' spirals. This shows that the observed optical colour of a spiral galaxy is determined almost equally by the spiral type (via the bulge-disc ratio and stellar populations), and reddening due to dust. We find that both luminosity and spiral type affect the total amount of extinction, with discy spirals at Mr ~ -21.5mag having the most reddening - more than twice as much as both the lowest luminosity and most massive, bulge-dominated spirals. An increase in dust content is well known for more luminous galaxies, but the decrease of the trend for the most luminous has not been observed before and may be related to their lower levels of recent star formation. We compare our results with the latest dust attenuation models of Tuffs et al. We find that the model reproduces the observed trends reasonably well but overpredicts the amount of u-band attenuation in edge-on galaxies. This could be an inadequacy in the Milky Way extinction law (when applied to external galaxies), but more likely indicates the need for a wider range of dust-star geometries. We end by discussing the effects of dust on large galaxy surveys and emphasize that these effects will become important as we push to higher precision measurements of galaxy properties and their clustering. This publication has been made possible by the participation of more than

  6. Evolutionary phenomena in galaxies

    International Nuclear Information System (INIS)

    Beckman, J.E.; Pagel, B.E.J.

    1989-01-01

    This book reviews the subject of evolutionary phenomena in galaxies, bringing together contributions by experts on all the relevant physics and astrophysics necessary to understand galaxies and how they work. The book is based on the proceedings of a conference held in July 1988 in Puerto de la Cruz, Tenerife which was timed to coincide with the first year of operation of the 4.2 m William Herschel Telescope. The broad topics covered include formation of galaxies and their ages, stellar dynamics, galactic scale gas and its role in star formation and the production and distribution of the chemical elements within galaxies. (author)

  7. The Inner Regions of Disk Galaxies: A Constant Baryonic Fraction?

    Directory of Open Access Journals (Sweden)

    Federico Lelli

    2014-07-01

    Full Text Available For disk galaxies (spirals and irregulars, the inner circular-velocity gradient dRV0 (inner steepness of the rotation curve correlates with the central surface brightness ∑*,0 with a slope of ~0.5. This implies that the central dynamical mass density scales almost linearly with the central baryonic density. Here I show that this empirical relation is consistent with a simple model where the central baryonic fraction ƒbar,0 is fixed to 1 (no dark matter and the observed scatter is due to differences in the baryonic mass-to-light ratio Mbar / LR (ranging from 1 to 3 in the R-band and in the characteristic thickness of the central stellar component Δz (ranging from 100 to 500 pc. Models with lower baryonic fractions are possible, although they require some fine-tuning in the values of Mbar/LR and Δz. Regardless of the actual value of ƒbar,0, the fact that different types of galaxies do not show strong variations in ƒbar,0 is surprising, and may represent a challenge for models of galaxy formation in a Λ Cold Dark Matter (ΛCDM cosmology.

  8. Violence in the hearts of galaxies: aberration or adolescence?

    Science.gov (United States)

    Mundell, Carole G

    2002-12-15

    Violent activity in the nuclei of galaxies has long been considered a curiosity in its own right; manifestations of this phenomenon include distant quasars in the early Universe and comparatively nearby Seyfert galaxies, both thought to be powered by the release of gravitational potential energy as material from the host galaxy accretes onto a central supermassive black hole (SMBH). Traditionally, the broader study of the formation, structure and evolution of galaxies has largely excluded active galactic nuclei. Recently, however, this situation has changed dramatically, both observationally and theoretically, with the realization that the growth and influence of the SMBH, the origin and development of galaxies and nuclear activity at different epochs in the Universe may be intimately related. The most spectacular fireworks seen in distant quasars may be relatively easy to explain, since the era of greatest quasar activity seems to coincide with turbulent dynamics at the epoch of galaxy formation in the young, gas-rich Universe. Ubiquitous black holes are believed to be a legacy of this violent birth. Alternatively, black holes may be the seeds that drive galaxy formation in the first place. Closer to home, and hence more recently in the history of the Universe, a fraction of comparatively ordinary galaxies, similar to our own, has reignited their central engines, albeit at a lower level of activity. Since these galaxies are more established than their younger and more distant counterparts, the activity here is all the more puzzling. Whatever the mechanisms involved, they are likely to play an important role in galaxy evolution. I review the intriguing evidence for causal links between SMBHs, nuclear activity and the formation and evolution of galaxies, and describe opportunities for testing these relationships using the next generation of earthbound and space-borne astronomical facilities.

  9. Violence in the hearts of galaxies: aberration or adolescence?

    Science.gov (United States)

    Mundell, Carole G.

    2002-12-01

    Violent activity in the nuclei of galaxies has long been considered a curiosity in its own right; manifestations of this phenomenon include distant quasars in the early Universe and comparatively nearby Seyfert galaxies, both thought to be powered by the release of gravitational potential energy as material from the host galaxy accretes onto a central supermassive black hole (SMBH). Traditionally, the broader study of the formation, structure and evolution of galaxies has largely excluded active galactic nuclei. Recently, however, this situation has changed dramatically, both observationally and theoretically, with the realization that the growth and influence of the SMBH, the origin and development of galaxies and nuclear activity at different epochs in the Universe may be intimately related. The most spectacular fireworks seen in distant quasars may be relatively easy to explain, since the era of greatest quasar activity seems to coincide with turbulent dynamics at the epoch of galaxy formation in the young, gas-rich Universe. Ubiquitous black holes are believed to be a legacy of this violent birth. Alternatively, black holes may be the seeds that drive galaxy formation in the first place. Closer to home, and hence more recently in the history of the Universe, a fraction of comparatively ordinary galaxies, similar to our own, has reignited their central engines, albeit at a lower level of activity. Since these galaxies are more established than their younger and more distant counterparts, the activity here is all the more puzzling. Whatever the mechanisms involved, they are likely to play an important role in galaxy evolution. I review the intriguing evidence for causal links between SMBHs, nuclear activity and the formation and evolution of galaxies, and describe opportunities for testing these relationships using the next generation of earthbound and space-borne astronomical facilities.

  10. EARLY-TYPE GALAXIES WITH TIDAL DEBRIS AND THEIR SCALING RELATIONS IN THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S4G)

    International Nuclear Information System (INIS)

    Kim, Taehyun; Sheth, Kartik; Muñoz-Mateos, Juan-Carlos; Hinz, Joannah L.; Zaritsky, Dennis; Lee, Myung Gyoon; Gadotti, Dimitri A.; Knapen, Johan H.; Schinnerer, Eva; Ho, Luis C.; Madore, Barry F.; Laurikainen, Eija; Salo, Heikki; Athanassoula, E.; Bosma, Albert; De Swardt, Bonita; Comerón, Sébastien; Regan, Michael W.; Menéndez-Delmestre, Karín; De Paz, Armando Gil

    2012-01-01

    Tidal debris around galaxies can yield important clues on their evolution. We have identified tidal debris in 11 early-type galaxies (T ≤ 0) from a sample of 65 early types drawn from the Spitzer Survey of Stellar Structure in Galaxies (S 4 G). The tidal debris includes features such as shells, ripples, and tidal tails. A variety of techniques, including two-dimensional decomposition of galactic structures, were used to quantify the residual tidal features. The tidal debris contributes ∼3%-10% to the total 3.6 μm luminosity of the host galaxy. Structural parameters of the galaxies were estimated using two-dimensional profile fitting. We investigate the locations of galaxies with tidal debris in the fundamental plane and Kormendy relation. We find that galaxies with tidal debris lie within the scatter of early-type galaxies without tidal features. Assuming that the tidal debris is indicative of recent gravitational interaction or merger, this suggests that these galaxies have either undergone minor merging events so that the overall structural properties of the galaxies are not significantly altered, or they have undergone a major merging events but already have experienced sufficient relaxation and phase mixing so that their structural properties become similar to those of the non-interacting early-type galaxies.

  11. Plan de negocios para el diseño y puesta en marcha de un bar temático en la ciudad de Quito

    OpenAIRE

    Carrera Clavijo, Paulina Alexandra; Cabrera Aguirre, Luis Fernando

    2013-01-01

    Beer Pong Bar and Grill is a theme bar; its name comes from the game that is also the bar is main attraction. This game is very popular in the US, especially in college and university fraternities, and bars around campus, it popularity has grown so much that even a National beer pong league was established, they host and organize many championships during the year and the master beer pong tournament every once a year, with big cash prices to all winners. Besides the game the bar will offer to...

  12. THE NUMBER OF TIDAL DWARF SATELLITE GALAXIES IN DEPENDENCE OF BULGE INDEX

    International Nuclear Information System (INIS)

    López-Corredoira, Martín; Kroupa, Pavel

    2016-01-01

    We show that a significant correlation (up to 5σ) emerges between the bulge index, defined to be larger for a larger bulge/disk ratio, in spiral galaxies with similar luminosities in the Galaxy Zoo 2 of the Sloan Digital Sky Survey and the number of tidal-dwarf galaxies in the catalog by Kaviraj et al. In the standard cold or warm dark matter cosmological models, the number of satellite galaxies correlates with the circular velocity of the dark matter host halo. In generalized gravity models without cold or warm dark matter, such a correlation does not exist, because host galaxies cannot capture infalling dwarf galaxies due to the absence of dark-matter-induced dynamical friction. However, in such models, a correlation is expected to exist between the bulge mass and the number of satellite galaxies because bulges and tidal-dwarf satellite galaxies form in encounters between host galaxies. This is not predicted by dark matter models in which bulge mass and the number of satellites are a priori uncorrelated because higher bulge/disk ratios do not imply higher dark/luminous ratios. Hence, our correlation reproduces the prediction of scenarios without dark matter, whereas an explanation is not found readily from the a priori predictions of the standard scenario with dark matter. Further research is needed to explore whether some application of the standard theory may explain this correlation

  13. Going Smokefree Matters - Bars and Restaurants Infographic

    Data.gov (United States)

    U.S. Department of Health & Human Services — Explore the Going Smokefree Matters – Bars and Restaurants Infographic which outlines key facts related to the effects of secondhand smoke exposure in bars and...

  14. Going Smokefree Matters - Bars and Restaurants Infographic

    Data.gov (United States)

    U.S. Department of Health & Human Services — Explore the Going Smokefree Matters – Bars and Restaurants Infographic which outlines key facts related to the effects of secondhand smoke exposure in bars and...

  15. The global warming of group satellite galaxies

    Science.gov (United States)

    Yozin, C.; Bekki, K.

    2016-08-01

    Recent studies adopting λRe, a proxy for specific angular momentum, have highlighted how early-type galaxies (ETGs) are composed of two kinematical classes for which distinct formation mechanisms can be inferred. With upcoming surveys expected to obtain λRe from a broad range of environments (e.g. SAMI, MaNGA), we investigate in this numerical study how the λRe-ɛe distribution of fast-rotating dwarf satellite galaxies reflects their evolutionary state. By combining N-body/SPH simulations of progenitor disc galaxies (stellar mass ≃109 M⊙), their cosmologically-motivated sub-halo infall history and a characteristic group orbit/potential, we demonstrate the evolution of a satellite ETG population driven by tidal interactions (e.g. harassment). As a general result, these satellites remain intrinsically fast-rotating oblate stellar systems since their infall as early as z = 2; mis-identifications as slow rotators often arise due to a bar/spiral lifecycle which plays an integral role in their evolution. Despite the idealistic nature of its construction, our mock λRe-ɛe distribution at z < 0.1 reproduces its observational counterpart from the ATLAS3D/SAURON projects. We predict therefore how the observed λRe-ɛe distribution of a group evolves according to these ensemble tidal interactions.

  16. The Evolution of Galaxies

    Czech Academy of Sciences Publication Activity Database

    Palouš, Jan

    2007-01-01

    Roč. 17, - (2007), s. 34-40 ISSN 1220-5168. [Heliospere and galaxy. Sinaia, 03.05.2007-05.05.2007] R&D Projects: GA MŠk(CZ) LC06014 Institutional research plan: CEZ:AV0Z10030501 Keywords : ISM structure * stars formation * evolution of galaxies Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  17. Hubble's Menagerie of Galaxies

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 3. Hubble's Managerie of Galaxies. Biman Nath. General Article Volume 14 Issue 3 March 2009 pp 226-235. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/014/03/0226-0235. Keywords. Galaxies ...

  18. Our galaxy is exploding

    International Nuclear Information System (INIS)

    Closets, Francois de.

    1977-01-01

    Improvements made in radioastronomy, and infrared, X and γ emission studies of the Galaxy have allowed to study the galactic nucleus, which is characterized by an intense activity. The most recent hypotheses made to explain this activity and replace it in the general context of the evolution of the galaxies are presented [fr

  19. Dwarf Elliptical Galaxies

    Science.gov (United States)

    Caldwell, N.; Murdin, P.

    2000-11-01

    DWARF SPHEROIDAL GALAXIES were first identified by Shapley, who had noticed two very diffuse collections of stars on Harvard patrol plates. Although these systems had about as many stars as a GLOBULAR CLUSTER, they were of much lower density, and hence much larger radius, and thus were considered distinct galaxies. These two, named Fornax and Sculptor after the constellations in which they ap...

  20. Hubble's Menagerie of Galaxies

    Indian Academy of Sciences (India)

    Srimath

    astronom ers have even w ondered ifH ubble's galaxy typ es form an evolutionary sequence: does one type of galaxy evolve into another? 1. T he D iscovery of G alaxies. A stronom ers began to ponder these issues only after they discovered w hat ...

  1. Visibility of galaxies

    International Nuclear Information System (INIS)

    Disney, M.J.

    1976-01-01

    It is stated that counts of galaxies could be seriously biased by selection effects, largely influenced by the brightness of the night sky. To illustrate this suppose the Earth were situated near the center of a giant elliptical galaxy. The mean surface brightness of the sky would then appear some 8 to 9 mag. brighter than is observed from our position in the Galaxy. Extragalactic space would then appear to be empty void; spiral and irregular galaxies would be invisible, and all that could be easily detected would be the core regions of galaxy ellipticals very similar to our own. Much of the Universe would be blinded by the surface brightness of the parent galaxy. This blinding, however, is a relative matter and the question arises as to what extent we are blinded by the spiral galaxy in which we exist. Strong indirect evidence exists that our knowledge of galaxies is heavily biased by the sky background, and the true population of extragalactic space may be very different from that seen. Other relevant work is also discussed, and further investigational work is indicated. (U.K.)

  2. The Mutable Galaxies -10 ...

    Indian Academy of Sciences (India)

    of spectacular explosions, called supernovae. The next generation stars which ... nova explosion of massive stars. Galaxies then must go throug;h this 'chemical' evolution, slowly changing the abundance of heavy elements in its gas and in stars. A spectacular .... small, which is the case in our galaxy. One finds that p is of ...

  3. Cold gas & mergers: fundamental difference in HI properties of different types of radio galaxies?

    NARCIS (Netherlands)

    Emonts, Bjorn; Morganti, Raffaella; Oosterloo, Tom; van Gorkom, Jacqueline

    2008-01-01

    We present results of a study of large-scale neutral hydrogen (HI) gas in nearby radio galaxies. We find that the early-type host galaxies of different types of radio sources (compact, FR-I and FR-II) appear to contain fundamentally different large-scale HI properties: enormous regular rotating

  4. Fossil evidence for spin alignment of Sloan Digital Sky Survey galaxies in filaments

    NARCIS (Netherlands)

    Jones, Bernard J. T.; van de Weijgaert, Marinus; Aragon-Calvo, Miguel A.

    2010-01-01

    We search for and find fossil evidence that the spin axes of galaxies in cosmic web filaments relative to their host filaments are not randomly distributed. This indicates the fact that the action of large-scale tidal torques affected the alignments of galaxies located in cosmic filaments. To this

  5. Timescales of merger, starburst and AGN activity in radio galaxy B2 0648+27

    NARCIS (Netherlands)

    Emonts, B. H. C.; Morganti, R.; Tadhunter, C. N.; Holt, J.; Oosterloo, T. A. V; Hulst, J. M. van der; Wills, K. A.

    We use neutral hydrogen (HI) and optical spectroscopic observations to compare the timescales of a merger event, starburst episode and radio-AGN activity in the radio galaxy B2 0648+27. We detect a large ring-like structure of HI in emission around the early-type host galaxy of B2 0648+27 (M-HI =

  6. A ROSAT survey of Wolf-Rayet galaxies - II. The extended sample

    Science.gov (United States)

    Stevens, Ian R.; Strickland, David K.

    1998-11-01

    We present results from an ongoing X-ray survey of Wolf-Rayet (WR) galaxies, a class of objects believed to be very young starbursts. This paper extends the first X-ray survey of WR galaxies by Stevens & Strickland by studying WR galaxies identified subsequent to the original WR galaxy catalogue of Conti. Out of a sample of 40 new WR galaxies a total of 10 have been observed with the ROSAT PSPC, and of these seven have been detected (NGC 1365, NGC 1569, I Zw 18, NGC 3353, NGC 4449, NGC 5408 and a marginal detection of NGC 2366). Of these, all are dwarf starbursts except for NGC 1365, which is a barred spiral galaxy possibly with an active nucleus. We also report on observations of the related emission-line galaxy IRAS 0833+6517. The X-ray properties of these galaxies are broadly in line with those found for the original sample; they are X-ray overluminous compared with their blue luminosity and have thermal spectra with typically kT~0.4-1.0keV. There are some oddities: NGC 5408 is very overluminous in X-rays, even compared with other WR galaxies; I Zw 18 has a harder X-ray spectrum; NGC 1365, although thought to contain an active nucleus, has X-ray properties that are broadly similar to other WR galaxies, and we suggest that the X-ray emission from NGC 1365 is due to starburst activity. A good correlation between X-ray and blue luminosity is found for the WR galaxy sample as a whole. However, when just dwarf galaxies are considered there is little evidence of correlation. We discuss the implications of these results on our understanding of the X-ray emission from WR galaxies and suggest that the best explanation for the X-ray activity is starburst activity from a young starburst region.

  7. Gas accretion onto galaxies

    CERN Document Server

    Davé, Romeel

    2017-01-01

    This edited volume presents the current state of gas accretion studies from both observational and theoretical perspectives, and charts our progress towards answering the fundamental yet elusive question of how galaxies get their gas. Understanding how galaxies form and evolve has been a central focus in astronomy for over a century. These studies have accelerated in the new millennium, driven by two key advances: the establishment of a firm concordance cosmological model that provides the backbone on which galaxies form and grow, and the recognition that galaxies grow not in isolation but within a “cosmic ecosystem” that includes the vast reservoir of gas filling intergalactic space. This latter aspect in which galaxies continually exchange matter with the intergalactic medium via inflows and outflows has been dubbed the “baryon cycle”. The topic of this book is directly related to the baryon cycle, in particular its least well constrained aspect, namely gas accretion. Accretion is a rare area of ast...

  8. MULTIPLE GALAXY COLLISIONS

    Science.gov (United States)

    2002-01-01

    Here is a sampling of 15 ultraluminous infrared galaxies viewed by NASA's Hubble Space Telescope. Hubble's sharp vision reveals more complexity within these galaxies, which astronomers are interpreting as evidence of a multiple-galaxy pileup. These images, taken by the Wide Field and Planetary Camera 2, are part of a three-year study of 123 galaxies within 3 billion light-years of Earth. The study was conducted in 1996, 1997, and 1999. False colors were assigned to these photos to enhance fine details within these coalescing galaxies. Credits: NASA, Kirk Borne (Raytheon and NASA Goddard Space Flight Center, Greenbelt, Md.), Luis Colina (Instituto de Fisica de Cantabria, Spain), and Howard Bushouse and Ray Lucas (Space Telescope Science Institute, Baltimore, Md.)

  9. Is the cluster environment quenching the Seyfert activity in elliptical and spiral galaxies?

    Science.gov (United States)

    de Souza, R. S.; Dantas, M. L. L.; Krone-Martins, A.; Cameron, E.; Coelho, P.; Hattab, M. W.; de Val-Borro, M.; Hilbe, J. M.; Elliott, J.; Hagen, A.; COIN Collaboration

    2016-09-01

    We developed a hierarchical Bayesian model (HBM) to investigate how the presence of Seyfert activity relates to their environment, herein represented by the galaxy cluster mass, M200, and the normalized cluster centric distance, r/r200. We achieved this by constructing an unbiased sample of galaxies from the Sloan Digital Sky Survey, with morphological classifications provided by the Galaxy Zoo Project. A propensity score matching approach is introduced to control the effects of confounding variables: stellar mass, galaxy colour, and star formation rate. The connection between Seyfert-activity and environmental properties in the de-biased sample is modelled within an HBM framework using the so-called logistic regression technique, suitable for the analysis of binary data (e.g. whether or not a galaxy hosts an AGN). Unlike standard ordinary least square fitting methods, our methodology naturally allows modelling the probability of Seyfert-AGN activity in galaxies on their natural scale, I.e. as a binary variable. Furthermore, we demonstrate how an HBM can incorporate information of each particular galaxy morphological type in an unified framework. In elliptical galaxies our analysis indicates a strong correlation of Seyfert-AGN activity with r/r200, and a weaker correlation with the mass of the host cluster. In spiral galaxies these trends do not appear, suggesting that the link between Seyfert activity and the properties of spiral galaxies are independent of the environment.

  10. The galaxy ancestor problem

    Science.gov (United States)

    Disney, M. J.; Lang, R. H.

    2012-11-01

    The Hubble Space Telescope (HST) findsgalaxies whose Tolman dimming exceeds 10 mag. Could evolution alone explain these as our ancestor galaxies or could they be representatives of quite a different dynasty whose descendants are no longer prominent today? We explore the latter hypothesis and argue that surface brightness selection effects naturally bring into focus quite different dynasties from different redshifts. Thus, the HST z = 7 galaxies could be examples of galaxies whose descendants are both too small and too choked with dust to be recognizable in our neighbourhood easily today. Conversely, the ancestors of the Milky Way and its obvious neighbours would have completely sunk below the sky at z > 1.2, unless they were more luminous in the past, although their diffused light could account for the missing re-ionization flux. This Succeeding Prominent Dynasties Hypothesis (SPDH) fits the existing observations both naturally and well even without evolution, including the bizarre distributions of galaxy surface brightness found in deep fields, the angular size ˜(1 + z)-1 law, 'downsizing' which turns out to be an 'illusion' in the sense that it does not imply evolution, 'infant mortality', that is, the discrepancy between stars born and stars seen, the existence of 'red nuggets', and finally the recently discovered and unexpected excess of quasar absorption line damped Lyα systems at high redshift. If galaxies were not significantly brighter in the past and the SPDH were true, then a large proportion of galaxies could remain sunk from sight, possibly at all redshifts, and these sunken galaxies could supply the missing re-ionization flux. We show that fishing these sunken galaxies out of the sky by their optical emissions alone is practically impossible, even when they are nearby. More ingenious methods are needed to detect them. It follows that disentangling galaxy evolution through studying ever higher redshift galaxies may be a forlorn hope because one could

  11. Bar code instrumentation for nuclear safeguards

    International Nuclear Information System (INIS)

    Bieber, A.M. Jr.

    1984-01-01

    This paper presents a brief overview of the basic principles of bar codes and the equipment used to make and to read bar code labels, and a summary of some of the more important factors that need to be considered in integrating bar codes into an information system

  12. The structural evolution of galaxies with both thin and thick discs

    Science.gov (United States)

    Aumer, Michael; Binney, James

    2017-09-01

    We perform controlled N-body simulations of disc galaxies growing within live dark matter (DM) haloes to present-day galaxies that contain both thin and thick discs. We consider two types of models: (a) thick-disc initial conditions to which stars on near-circular orbits are continuously added over ˜10 Gyr, and (b) models in which the birth velocity dispersion of stars decreases continuously over the same time-scale. We show that both schemes produce double-exponential vertical profiles similar to that of the Milky Way (MW). We indicate how the spatial age structure of galaxies can be used to discriminate between scenarios. We show that the presence of a thick disc significantly alters and delays bar formation and thus makes possible models with a realistic bar and a high baryon-to-DM mass ratio in the central regions, as required by microlensing constraints. We examine how the radial mass distribution in stars and DM is affected by disc growth and non-axisymmetries. We discuss how bar buckling shapes the vertical age distribution of thin- and thick-disc stars in the bar region. The extent to which the combination of observationally motivated inside-out growth histories and cosmologically motivated dark halo properties leads to the spontaneous formation of non-axisymmetries that steer the models towards present-day MW-like galaxies is noteworthy.

  13. Jackson Bar Training Structure Study

    Science.gov (United States)

    2015-05-01

    0.039 7 Creek 0.028 8 Jackson Bar 0.032 9 Jackson Bar Dredge Cut 0.032 10 Left Bridge 0.038 11 Right Bridge 0.038 12 Over Bank 0.04 13 Rip- Rap ...15 20 25 30 35 Si m ul at ed b as e da ta , w at er s ur fa ce el ev at io n N G VD 1 92 9 fe et Leroy field data, water surface elevation...and 1987 WES PM bathymetry 573 ft upstream of the Norfolk Southern railroad bridge. -30 -20 -10 0 10 20 30 40 0 500 1000 1500 2000 El ev at

  14. The Influence of Galaxy Environment on the Stellar Initial Mass Function of Early-Type Galaxies

    Science.gov (United States)

    Rosani, Giulio; Pasquali, Anna; La Barbera, Francesco; Ferreras, Ignacio; Vazdekis, Alexandre

    2018-02-01

    In this paper we investigate whether the stellar initial mass function of early-type galaxies depends on their host environment. To this purpose, we have selected a sample of early-type galaxies from the SPIDER catalogue, characterized their environment through the group catalogue of Wang et al. and used their optical SDSS spectra to constrain the IMF slope, through the analysis of IMF-sensitive spectral indices. To reach a high enough signal-to-noise ratio, we have stacked spectra in velocity dispersion (σ0) bins, on top of separating the sample by galaxy hierarchy and host halo mass, as proxies for galaxy environment. In order to constrain the IMF, we have compared observed line strengths to predictions of MIUSCAT/EMILES synthetic stellar population models, with varying age, metallicity, and "bimodal" (low-mass tapered) IMF slope (Γ _b). Consistent with previous studies, we find that Γ _b increases with σ0, becoming bottom-heavy (i.e. an excess of low-mass stars with respect to the Milky-Way-like IMF) at high σ0. We find that this result is robust against the set of isochrones used in the stellar population models, as well as the way the effect of elemental abundance ratios is taken into account. We thus conclude that it is possible to use currently state-of-the-art stellar population models and intermediate resolution spectra to consistently probe IMF variations. For the first time, we show that there is no dependence of Γb on environment or galaxy hierarchy, as measured within the 3″ SDSS fibre, thus leaving the IMF as an intrinsic galaxy property, possibly set already at high redshift.

  15. Bar-holding prosthetic limb

    Science.gov (United States)

    Vest, Thomas W. (Inventor); Norton, William E. (Inventor); Belcher, Jewell G. (Inventor); Carden, James R. (Inventor)

    1992-01-01

    A prosthetic device for below-the-elbow amputees is disclosed. The device has a removable effector, which is attached to the end of an arm cuff. The effector is comprised of a pair of C-shaped members that are oriented so as to face each other. Working in concert, the C-shaped members are able to hold a bar such as a chainsaw handle. A flat spring is fitted around the C-shaped members to hold them together.

  16. Are spiral galaxies heavy smokers?

    International Nuclear Information System (INIS)

    Davies, J.; Disney, M.; Phillipps, S

    1990-01-01

    The dustiness of spiral galaxies is discussed. Starburst galaxies and the shortage of truly bright spiral galaxies is cited as evidence that spiral galaxies are far dustier than has been thought. The possibility is considered that the dust may be hiding missing mass

  17. Bar Coding and Tracking in Pathology.

    Science.gov (United States)

    Hanna, Matthew G; Pantanowitz, Liron

    2016-03-01

    Bar coding and specimen tracking are intricately linked to pathology workflow and efficiency. In the pathology laboratory, bar coding facilitates many laboratory practices, including specimen tracking, automation, and quality management. Data obtained from bar coding can be used to identify, locate, standardize, and audit specimens to achieve maximal laboratory efficiency and patient safety. Variables that need to be considered when implementing and maintaining a bar coding and tracking system include assets to be labeled, bar code symbologies, hardware, software, workflow, and laboratory and information technology infrastructure as well as interoperability with the laboratory information system. This article addresses these issues, primarily focusing on surgical pathology. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. The Impact of Assembly Bias on the Galaxy Content of Dark Matter Halos

    Science.gov (United States)

    Zehavi, Idit; Contreras, Sergio; Padilla, Nelson; Smith, Nicholas J.; Baugh, Carlton M.; Norberg, Peder

    2018-01-01

    We study the dependence of the galaxy content of dark matter halos on large-scale environment and halo formation time using semi-analytic galaxy models applied to the Millennium simulation. We analyze subsamples of halos at the extremes of these distributions and measure the occupation functions for the galaxies they host. We find distinct differences among these occupation functions. The main effect with environment is that central galaxies (and in one model, also the satellites) in denser regions start populating lower-mass halos. A similar, but significantly stronger, trend exists with halo age, where early-forming halos are more likely to host central galaxies at lower halo mass. We discuss the origin of these trends and the connection to the stellar mass–halo mass relation. We find that, at fixed halo mass, older halos and to some extent also halos in dense environments tend to host more massive galaxies. Additionally, we see a reverse trend for the occupation of satellite galaxies where early-forming halos have fewer satellites, likely due to having more time for them to merge with the central galaxy. We describe these occupancy variations in terms of the changes in the occupation function parameters, which can aid in constructing realistic mock galaxy samples. Finally, we study the corresponding galaxy auto- and cross-correlation functions of the different samples and elucidate the impact of assembly bias on galaxy clustering. Our results can inform theoretical modeling of galaxy assembly bias and attempts to detect it in the real universe.

  19. Dwarf galaxies : Important clues to galaxy formation

    NARCIS (Netherlands)

    Tolstoy, E

    2003-01-01

    The smallest dwarf galaxies are the most straight forward objects in which to study star formation processes on a galactic scale. They are typically single cell star forming entities, and as small potentials in orbit around a much larger one they are unlikely to accrete much (if any) extraneous

  20. Accretion by the Galaxy

    Directory of Open Access Journals (Sweden)

    Binney J.

    2012-02-01

    Full Text Available Cosmology requires at least half of the baryons in the Universe to be in the intergalactic medium, much of which is believed to form hot coronae around galaxies. Star-forming galaxies must be accreting from their coronae. Hi observations of external galaxies show that they have Hi halos associated with star formation. These halos are naturally modelled as ensembles of clouds driven up by supernova bubbles. These models can fit the data successfully only if clouds exchange mass and momentum with the corona. As a cloud orbits, it is ablated and forms a turbulent wake where cold high-metallicity gas mixes with hot coronal gas causing the prompt cooling of the latter. As a consequence the total mass of Hi increases. This model has recently been used to model the Leiden-Argentina-Bonn survey of Galactic Hi. The values of the model’s parameters that are required to model NGC 891, NGC 2403 and our Galaxy show a remarkable degree of consistency, despite the very different natures of the two external galaxies and the dramatic difference in the nature of the data for our Galaxy and the external galaxies. The parameter values are also consistent with hydrodynamical simulations of the ablation of individual clouds. The model predicts that a galaxy that loses its cool-gas disc for instance through a major merger cannot reform it from its corona; it can return to steady star formation only if it can capture a large body of cool gas, for example by accreting a gas-rich dwarf. Thus the model explains how major mergers can make galaxies “red and dead.”

  1. Quenching or Bursting: Star Formation Acceleration—A New Methodology for Tracing Galaxy Evolution

    Science.gov (United States)

    Martin, D. Christopher; Gonçalves, Thiago S.; Darvish, Behnam; Seibert, Mark; Schiminovich, David

    2017-06-01

    We introduce a new methodology for the direct extraction of galaxy physical parameters from multiwavelength photometry and spectroscopy. We use semianalytic models that describe galaxy evolution in the context of large-scale cosmological simulation to provide a catalog of galaxies, star formation histories, and physical parameters. We then apply models of stellar population synthesis and a simple extinction model to calculate the observable broadband fluxes and spectral indices for these galaxies. We use a linear regression analysis to relate physical parameters to observed colors and spectral indices. The result is a set of coefficients that can be used to translate observed colors and indices into stellar mass, star formation rate, and many other parameters, including the instantaneous time derivative of the star formation rate, which we denote the Star Formation Acceleration (SFA), We apply the method to a test sample of galaxies with GALEX photometry and SDSS spectroscopy, deriving relationships between stellar mass, specific star formation rate, and SFA. We find evidence for a mass-dependent SFA in the green valley, with low-mass galaxies showing greater quenching and higher-mass galaxies greater bursting. We also find evidence for an increase in average quenching in galaxies hosting an active galactic nucleus. A simple scenario in which lower-mass galaxies accrete and become satellite galaxies, having their star-forming gas tidally and/or ram-pressure stripped, while higher-mass galaxies receive this gas and react with new star formation, can qualitatively explain our results.

  2. Quenching or Bursting: Star Formation Acceleration—A New Methodology for Tracing Galaxy Evolution

    Energy Technology Data Exchange (ETDEWEB)

    Martin, D. Christopher; Darvish, Behnam; Seibert, Mark [California Institute of Technology, MC 405-47, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Gonçalves, Thiago S. [Observatorio do Valongo, Universidade Federal do Rio de Janeiro, Ladeira Pedro Antonio, 43, Saude, Rio de Janeiro-RJ 20080-090 (Brazil); Schiminovich, David [Department of Astronomy, Columbia University, New York, NY 10027 (United States)

    2017-06-10

    We introduce a new methodology for the direct extraction of galaxy physical parameters from multiwavelength photometry and spectroscopy. We use semianalytic models that describe galaxy evolution in the context of large-scale cosmological simulation to provide a catalog of galaxies, star formation histories, and physical parameters. We then apply models of stellar population synthesis and a simple extinction model to calculate the observable broadband fluxes and spectral indices for these galaxies. We use a linear regression analysis to relate physical parameters to observed colors and spectral indices. The result is a set of coefficients that can be used to translate observed colors and indices into stellar mass, star formation rate, and many other parameters, including the instantaneous time derivative of the star formation rate, which we denote the Star Formation Acceleration (SFA), We apply the method to a test sample of galaxies with GALEX photometry and SDSS spectroscopy, deriving relationships between stellar mass, specific star formation rate, and SFA. We find evidence for a mass-dependent SFA in the green valley, with low-mass galaxies showing greater quenching and higher-mass galaxies greater bursting. We also find evidence for an increase in average quenching in galaxies hosting an active galactic nucleus. A simple scenario in which lower-mass galaxies accrete and become satellite galaxies, having their star-forming gas tidally and/or ram-pressure stripped, while higher-mass galaxies receive this gas and react with new star formation, can qualitatively explain our results.

  3. Revisiting The First Galaxies: The epoch of Population III stars

    Energy Technology Data Exchange (ETDEWEB)

    Muratov, Alexander L. [U. Michigan, Dept. Astron.; Gnedin, Oleg Y. [U. Michigan, Dept. Astron.; Gnedin, Nickolay Y. [Chicago U., Astron. Astrophys. Ctr.; Zemp, Marcel [Beijing, KITPC

    2013-07-19

    We investigate the transition from primordial Population III (Pop III) star formation to normal Pop II star formation in the first galaxies using new cosmological hydrodynamic simulations. We find that while the first stars seed their host galaxies with metals, they cannot sustain significant outflows to enrich the intergalactic medium, even assuming a top-heavy initial mass function. This means that Pop III star formation could potentially continue until z 6 in different unenriched regions of the universe, before being ultimately shut off by cosmic reionization. Within an individual galaxy, the metal production and stellar feedback from Pop II stars overtake Pop III stars in 20-200 Myr, depending on galaxy mass.

  4. Do AGN and galaxies truly co-evolve?

    Science.gov (United States)

    Fiore, Fabrizio

    2014-11-01

    Why did galaxies during their cosmological evolution stop to form stars? Why black holes in galactic nuclei have masses proportional to bulge masses? A mantra developed in the latter years suggests that AGN driven outflows may play a major role in galaxy evolution, but, is this truly the case? I will review searches for AGN feedback using X-ray, O/NIR and mm observations, and present new correlations between outflow kinetic energy, the Eddington ratio and the host galaxy SF efficiency. I will then discuss whether these observations can distinguish between two broad scenarios. In the first AGN winds regulates both further nuclear accretion and SF. In the second the correlations are interpreted as scaling laws where gas accretion and ejection and SF scale according to the galaxy size.

  5. Black-hole-regulated star formation in massive galaxies.

    Science.gov (United States)

    Martín-Navarro, Ignacio; Brodie, Jean P; Romanowsky, Aaron J; Ruiz-Lara, Tomás; van de Ven, Glenn

    2018-01-18

    Supermassive black holes, with masses more than a million times that of the Sun, seem to inhabit the centres of all massive galaxies. Cosmologically motivated theories of galaxy formation require feedback from these supermassive black holes to regulate star formation. In the absence of such feedback, state-of-the-art numerical simulations fail to reproduce the number density and properties of massive galaxies in the local Universe. There is, however, no observational evidence of this strongly coupled coevolution between supermassive black holes and star formation, impeding our understanding of baryonic processes within galaxies. Here we report that the star formation histories of nearby massive galaxies, as measured from their integrated optical spectra, depend on the mass of the central supermassive black hole. Our results indicate that the black-hole mass scales with the gas cooling rate in the early Universe. The subsequent quenching of star formation takes place earlier and more efficiently in galaxies that host higher-mass central black holes. The observed relation between black-hole mass and star formation efficiency applies to all generations of stars formed throughout the life of a galaxy, revealing a continuous interplay between black-hole activity and baryon cooling.

  6. The Universe's Most Extreme Star-forming Galaxies

    Science.gov (United States)

    Casey, Caitlin

    2017-06-01

    Dusty star-forming galaxies host the most intense stellar nurseries in the Universe. Their unusual characteristics (SFRs=200-2000Msun/yr, Mstar>1010 Msun) pose a unique challenge for cosmological simulations and galaxy formation theory, particularly at early times. Although rare today, they were factors of 1000 times more prevalent at z~2-5, contributing significantly to the buildup of the Universe's stellar mass and the formation of high-mass galaxies. At even earlier times (within 1Gyr post Big Bang) they could have played a pivotal role in enriching the IGM. However, an ongoing debate lingers as to their evolutionary origins at high-redshift, whether or not they are triggered by major mergers of gas-rich disk galaxies, or if they are solitary galaxies continually fed pristine gas from the intergalactic medium. Furthermore, their presence in early protoclusters, only revealed quite recently, pose intriguing questions regarding the collapse of large scale structure. I will discuss some of the latest observational programs dedicated to understanding dust-obscuration in and gas content of the early Universe, their context in the cosmic web, and future long-term observing campaigns that may reveal their relationship to `normal’ galaxies, thus teaching us valuable lessons on the physical mechanisms of galaxy growth and the collapse of large scale structure in an evolving Universe.

  7. Black-hole-regulated star formation in massive galaxies

    Science.gov (United States)

    Martín-Navarro, Ignacio; Brodie, Jean P.; Romanowsky, Aaron J.; Ruiz-Lara, Tomás; van de Ven, Glenn

    2018-01-01

    Supermassive black holes, with masses more than a million times that of the Sun, seem to inhabit the centres of all massive galaxies. Cosmologically motivated theories of galaxy formation require feedback from these supermassive black holes to regulate star formation. In the absence of such feedback, state-of-the-art numerical simulations fail to reproduce the number density and properties of massive galaxies in the local Universe. There is, however, no observational evidence of this strongly coupled coevolution between supermassive black holes and star formation, impeding our understanding of baryonic processes within galaxies. Here we report that the star formation histories of nearby massive galaxies, as measured from their integrated optical spectra, depend on the mass of the central supermassive black hole. Our results indicate that the black-hole mass scales with the gas cooling rate in the early Universe. The subsequent quenching of star formation takes place earlier and more efficiently in galaxies that host higher-mass central black holes. The observed relation between black-hole mass and star formation efficiency applies to all generations of stars formed throughout the life of a galaxy, revealing a continuous interplay between black-hole activity and baryon cooling.

  8. ALMA Explores How Supermassive Black Holes Talk to Their Galaxies

    Science.gov (United States)

    Kohler, Susanna

    2017-03-01

    We believe that supermassive black holes evolve in tandem with their host galaxies but how do the two communicate? Observations from the Atacama Large Millimeter/submillimeter Array (ALMA) have revealed new clues about how a monster black hole talks to its galaxy.A Hubble image of the central galaxy in the Phoenix cluster. [Adapted from Russell et al. 2017]Observing FeedbackActive galactic nuclei (AGN), the highly luminous centers of some galaxies, are thought to radiate due to active accretion onto the supermassive black hole at their center.Its long been suspected that the radiation and outflowing material which often takes the form of enormous bipolar radio jets emitted into the surroundings influence the AGNs host galaxy, affecting star formation rates and the evolution of the galaxy. This AGN feedback has been alternately suggested to trigger star formation, quench it, and truncate the growth of massive galaxies.The details of this feedback process, however, have yet to be thoroughly understood in part because its difficult to obtain detailed observations of how AGN outflows interact with the galactic gas surrounding them. Now, a team of scientists led by Helen Russell (Institute of Astronomy in Cambridge, UK) has published the results of a new, high-resolution look at the gas in a massive galaxy in the center of the Phoenix cluster.Many Uses for FuelThe Phoenix cluster, a nearby (z = 0.596) group of star-forming galaxies, is the most luminous X-ray cluster known. The central galaxy in the cluster is especially active: it hosts a starburst of 500800 solar masses per year, the largest starburst found in any galaxy below a redshift of z= 1.The star formation in this galaxy is sustained by an enormous reservoir of cold molecular gas roughly 20 billion solar masses worth. Thi