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Sample records for osubgs sample galaxies

  1. The Arecibo Galaxy Environment Survey IX: the isolated galaxy sample

    NASA Astrophysics Data System (ADS)

    Minchin, R. F.; Auld, R.; Davies, J. I.; Karachentsev, I. D.; Keenan, O. C.; Momjian, E.; Rodriguez, R.; Taber, T.; Taylor, R.

    2016-02-01

    We have used the Arecibo L-band Feed Array (ALFA) to map three regions, each of 5 deg2, around the isolated galaxies NGC 1156, UGC 2082, and NGC 5523. In the vicinity of these galaxies we have detected two dwarf companions: one near UGC 2082, previously discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey, and one near NGC 1156, discovered by this project and reported in an earlier paper. This is significantly fewer than the 15.4^{+1.7}_{-1.5} that would be expected from the field H I mass function from ALFALFA or the 8.9 ± 1.2 expected if the H I mass function from the Local Group applied in these regions. The number of dwarf companions detected is, however, consistent with a flat or declining H I mass function as seen by a previous, shallower, H I search for companions to isolated galaxies. We attribute this difference in H I mass functions to the different environments in which they are measured. This agrees with the general observation that lower ratios of dwarf to giant galaxies are found in lower density environments.

  2. Relativistic effects on galaxy redshift samples due to target selection

    NASA Astrophysics Data System (ADS)

    Alam, Shadab; Croft, Rupert A. C.; Ho, Shirley; Zhu, Hongyu; Giusarma, Elena

    2017-10-01

    In a galaxy redshift survey, the objects to be targeted for spectra are selected from a photometrically observed sample. The observed magnitudes and colours of galaxies in this parent sample will be affected by their peculiar velocities, through relativistic Doppler and relativistic beaming effects. In this paper, we compute the resulting expected changes in galaxy photometry. The magnitudes of the relativistic effects are a function of redshift, stellar mass, galaxy velocity and velocity direction. We focus on the CMASS sample from the Sloan Digital Sky Survey (SDSS) and Baryon Oscillation Spectroscopic Survey (BOSS), which is selected on the basis of colour and magnitude. We find that 0.10 per cent of the sample (∼585 galaxies) has been scattered into the targeted region of colour-magnitude space by relativistic effects, and conversely 0.09 per cent of the sample (∼532 galaxies) has been scattered out. Observational consequences of these effects include an asymmetry in clustering statistics, which we explore in a companion paper. Here, we compute a set of weights that can be used to remove the effect of modulations introduced into the density field inferred from a galaxy sample. We conclude by investigating the possible effects of these relativistic modulation on large-scale clustering of the galaxy sample.

  3. Turbulence and Star Formation in a Sample of Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Maier, Erin; Chien, Li-Hsin; Hunter, Deidre A.

    2016-11-01

    We investigate turbulent gas motions in spiral galaxies and their importance to star formation in far outer disks, where the column density is typically far below the critical value for spontaneous gravitational collapse. Following the methods of Burkhart et al. on the Small Magellanic Cloud, we use the third and fourth statistical moments, as indicators of structures caused by turbulence, to examine the neutral hydrogen (H i) column density of a sample of spiral galaxies selected from The H i Nearby Galaxy Survey. We apply the statistical moments in three different methods—the galaxy as a whole, divided into a function of radii and then into grids. We create individual grid maps of kurtosis for each galaxy. To investigate the relation between these moments and star formation, we compare these maps with their far-ultraviolet images taken by the Galaxy Evolution Explorer satellite.We find that the moments are largely uniform across the galaxies, in which the variation does not appear to trace any star-forming regions. This may, however, be due to the spatial resolution of our analysis, which could potentially limit the scale of turbulent motions that we are sensitive to greater than ∼700 pc. From comparison between the moments themselves, we find that the gas motions in our sampled galaxies are largely supersonic. This analysis also shows that the Burkhart et al. methods may be applied not just to dwarf galaxies but also to normal spiral galaxies.

  4. Galaxy Evolution in Mass-Selected Samples

    NASA Astrophysics Data System (ADS)

    Fontana, Adriano

    I summarize the recent results from the HDFS and K20 surveys that allow to trace the evolution of massive galaxies up to z≃ 3. I show that the evolution of both the specific star-formation rate and of the stellar mass density suggest that, at z>1, we observe the epoch where the evolution of massive objects becomes appreciable. At z≃ 1.8, we indeed find that about 40% of the local density has been locked in massive galaxies. This is associated with a change in the physical properties of massive galaxies, with star-forming objects that contribute to a substantial fraction of the observed mass density. I quantitatively show that these results do not pose challenges to current Λ-CDM models, but represent valuable constraints to understand the complex physical mechanisms involved in the assembly of massive galaxies.

  5. Properties of an H I-selected galaxy sample

    NASA Technical Reports Server (NTRS)

    Szomoru, Arpad; Guhathakurta, Puragra; Van Gorkom, Jacqueline H.; Knapen, Johan H.; Weinberg, David H.; Fruchter, Andrew S.

    1994-01-01

    We analyze the properties of a sample of galaxies identified in a 21cm, H I-line survey of selected areas in the Perseus-Pisces supercluster and its foreground void. Twelve fields were observed in the supercluster, five of them (target fields) centered on optically bright galaxies, and the other seven (blank fields) selected to contain no bright galaxies within 45 min. of their centers. We detected nine previously uncatalogued, gas-rich galaxies, six of them in the target fields. We also detected H I from seven previously catalogued galaxies in these fields. Observations in the void covered the same volume as the 12 supercluster fields at the same H I-mass sensitivity, but no objects were detected. Combining out H I data with optical broadband and H alpha imaging, we conclude that the properties of H I-selected galaxies do not differ substantially from those of late-type galaxies found in optical surveys. In particular, the galaxies in our sample do not appear to be unusually faint for their H I mass, or for their circular velocity. We find tentative evidence for a connection between optical surface brightness and degree of isolation, in the sense that low surface brightness galaxies tend to be more isolated. The previously catalogued, optically bright galaxies in our survey volume dominate the total H I mass density and cross section; the uncatalogued galaxies contribute only approximately 19 percent of the mass and approximately 12 percent of the cross section. Thus, existing estimates of the density and cross section of neutral hydrogen, most of which are based on optically selected galaxy samples, are probably accurate. Such estimates can be used to compare the nearby universe to the high-redshift universe probed by quasar absorption lines.

  6. Turbulence and Star Formation in a Sample of Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Maier, Erin R.; Hunter, Deidre Ann; Chien, Li-Hsin

    2016-01-01

    We investigate turbulent gas motions in spiral galaxies and their importance to star formation in far outer disks, where the column density is typically far below the critical value for spontaneous gravitational collapse. Following the methods of Burkhart et al. (2010) as applied to the Small Magellanic Cloud, we use the third and fourth statistical moments, skewness and kurtosis, which are indicators of structures caused by turbulence, to examine the integrated neutral hydrogen (Hι) column density of a sample of spiral galaxies selected from The Hι Nearby Galaxy Survey (THINGS, Walter et al. 2008). We examine the kurtosis and skewness values of each galaxy as a whole, as well as their variation as a function of radius and in discrete sub-regions defined by a square, moving 'kernel,' essentially splitting each galaxy into a grid. We then create individual grid maps of kurtosis and skewness for each galaxy. To investigate the relation between these moments and star formation, we compare these maps with maps of each galaxy's far-ultraviolet (FUV) image, taken by the Galaxy Evolution Explorer (GALEX) satellite. We find that the moments are largely uniform across the galaxies: the variation does not appear to trace any star forming regions. This may, however, be due to the spatial resolution of our analysis, which could potentially limit the scale of turbulent motions to at most ~700 pc. From our analysis of the comparison between the two moments themselves, we find that the gas motions in our sample galaxies are largely supersonic. This analysis shows that Burkhart et al. (2010)'s methods may be applied not just to dwarf galaxies but normal spiral galaxies as well.We acknowledge the NSF for their funding of this work through their Research Experience for Undergraduates (REU) program (Grant No. AST-1461200).

  7. Characterisation of an isolated galaxy sample: Astrophysical implications

    NASA Astrophysics Data System (ADS)

    Argudo Fernandez, Maria del Carmen

    2013-11-01

    In order to understand the evolution of galaxies, it is necessary to have a reference sample where the effects of the environment are minimised and quantified. Recent advances in large redshift galaxy surveys, such as the Sloan Digital Sky Survey (SDSS-DR9), allow to reach a 3-dimensional picture of the environment. In the first two parts of the thesis, we present, in the framework of the AMIGA project (Analysis of the interstellar Medium of Isolated GAlaxies), a revision of the isolation degree and a study of the 3-dimensional environment for galaxies in the Catalogue of Isolated Galaxies (CIG, Karachentseva 1973). Using the 3-dimensional information, new catalogues of isolated galaxies, isolated pairs, and isolated triplets are assembled in the third part of the thesis. The main aims of this thesis are: * to refine the photographic-based CIG and to provide an improvement of the quantification of the isolation degree with respect to previous works, using both photometry and spectroscopy; * to identify and quantify the effects of the physical satellite distribution around galaxies in the CIG, as well as the effects of the Large Scale Structure (LSS); * to construct a catalogue of galaxies isolated in 3-dimension, and build catalogues of physically associated isolated pairs and isolated triplets. We develop an automatic method to search for neighbours around each CIG galaxy in the SDSS, within a projected area up to 3 Mpc. To recover the physically bound neighbour galaxies we focus on the satellites which are within the escape speed of each CIG galaxy. The local number density, at the 5 th nearest neighbour, and the tidal strength affecting the CIG galaxy are estimated to quantify the local and LSS isolation degrees. For the first time, the environment and the isolation degree of CIG galaxies are quantified using digital data. Besides, the availability of the spectroscopic data allows us to check the validity of the CIG isolation criterion, and shows that it is not

  8. The AMIGA sample of isolated galaxies. X. A first look at isolated galaxy colors

    NASA Astrophysics Data System (ADS)

    Fernández Lorenzo, M.; Sulentic, J.; Verdes-Montenegro, L.; Ruiz, J. E.; Sabater, J.; Sánchez, S.

    2012-04-01

    Context. The basic properties of galaxies can be affected by both nature (internal processes) or nurture (interactions and effects of environment). Deconvolving the two effects is an important current effort in astrophysics. Observed properties of a sample of isolated galaxies should be mainly the result of internal (natural) evolution. It follows that nurture-induced galaxy evolution can only be understood through a comparative study of galaxies in different environments. Aims: We take a first look at SDSS (g - r) colors of galaxies in the AMIGA sample, which consists of many of the most isolated galaxies in the local Universe. This alerted us at the same time to the pitfalls of using automated SDSS colors. Methods: We focused on median values for the principal morphological subtypes found in the AMIGA sample (E/S0 and Sb-Sc) and compared them with equivalent measures obtained for galaxies in denser environments. Results: We find a weak tendency for AMIGA spiral galaxies to be redder than objects in close pairs. We find no clear difference when we compared this with galaxies in other (e.g. group) environments. However, the (g - r) color of isolated galaxies shows a Gaussian distribution, as might be expected assuming nurture-free evolution. We find a smaller median absolute deviation in colors for isolated galaxies compared to both wide and close pairs. The majority of the deviation on median colors for spiral subtypes is caused by a color-luminosity correlation. Surprisingly, isolated and non-isolated early-type galaxies show similar (g - r). We see little evidence for a green valley in our sample because most spirals redder than (g - r) = 0.7 have spurious colors. Conclusions: The redder colors of AMIGA spirals and lower color dispersions for AMIGA subtypes - compared with close pairs - are likely caused by a more passive star formation in very isolated galaxies. Full Tables 1 and 2 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130

  9. The AMIGA sample of isolated galaxies. IV. A catalogue of neighbours around isolated galaxies

    NASA Astrophysics Data System (ADS)

    Verley, S.; Odewahn, S. C.; Verdes-Montenegro, L.; Leon, S.; Combes, F.; Sulentic, J.; Bergond, G.; Espada, D.; García, E.; Lisenfeld, U.; Sabater, J.

    2007-08-01

    Context: Studies of the effects of environment on galaxy properties and evolution require well defined control samples. Such isolated galaxy samples have up to now been small or poorly defined. The AMIGA project (Analysis of the interstellar Medium of Isolated GAlaxies) represents an attempt to define a statistically useful sample of the most isolated galaxies in the local (z ≤ 0.05) Universe. Aims: A suitable large sample for the AMIGA project already exists, the Catalogue of Isolated Galaxies (CIG, Karachentseva, 1973, Astrofizicheskie Issledovaniia Izvestiya Spetsial'noj Astrofizicheskoj Observatorii, 8, 3; 1050 galaxies), and we use this sample as a starting point to refine and perform a better quantification of its isolation properties. Methods: Digitised POSS-I E images were analysed out to a minimum projected radius R ≥ 0.5 Mpc around 950 CIG galaxies (those within Vr = 1500 km s-1 were excluded). We identified all galaxy candidates in each field brighter than B = 17.5 with a high degree of confidence using the LMORPHO software. We generated a catalogue of approximately 54 000 potential neighbours (redshifts exist for ≈30% of this sample). Results: Six hundred sixty-six galaxies pass and two hundred eighty-four fail the original CIG isolation criterion. The available redshift data confirm that our catalogue involves a largely background population rather than physically associated neighbours. We find that the exclusion of neighbours within a factor of four in size around each CIG galaxy, employed in the original isolation criterion, corresponds to Δ Vr ≈ 18 000 km s-1 indicating that it was a conservative limit. Conclusions: Galaxies in the CIG have been found to show different degrees of isolation. We conclude that a quantitative measure of this is mandatory. It will be the subject of future work based on the catalogue of neighbours obtained here. Full Table [see full text] is only available in electronic form at the CDS via anonymous ftp to cdsarc

  10. Fourier photometric analysis of isolated galaxies in the context of the AMIGA project

    NASA Astrophysics Data System (ADS)

    Durbala, A.; Buta, R.; Sulentic, J. W.; Verdes-Montenegro, L.

    2009-08-01

    We present here the results of a Fourier photometric decomposition of a representative sample of ~100 isolated CIG galaxies (Catalog of Isolated Galaxies) in the morphological range Sb-Sc. This study is an integral part of the AMIGA (Analysis of the Interstellar Medium of Isolated Galaxies) project. It complements the photometric analysis presented in our previous paper for the same sample of disc galaxies by allowing a description of the spiral structure morphology. We also estimate dynamical measures like torque strength for bar and spiral, and also the total non-axisymmetric torque by assuming a constant mass-to-light ratio, and explore the interplay between the spiral and bar components of galaxies. Both the length (lbar) and the contrast (e.g. A2b) of the Fourier bars decrease along the morphological sequence Sb-Sbc-Sc, with bars in earlier types being longer and showing higher contrast. The bars of Sb galaxies are ~three times longer than the bars in Sc types, consistent with our previous study. We find that the longer bars are not necessarily stronger (as quantified by the torque Qb measure), but longer bars show a higher contrast A2b, in very good agreement with theoretical predictions. Our data suggest that bar and spiral components are rather independent in the sense that the torque strengths of the two components are not correlated. The total strength Qg is a very reliable tracer of the bar strength measure Qb, the two quantities showing a very tight linear correlation. Comparison with a similar sample of disc galaxies (same morphological range) extracted from the OSUBGS (Ohio State University Bright Galaxy Survey) indicates that the isolated CIG/AMIGA galaxies host significantly longer Fourier bars and possibly show a different distribution of spiral torque Qs. The Fourier analysis also revealed a potential case of counterwinding spiral structure (KIG652/NGC5768), which deserves further kinematic study. We find that m = 2 (i.e. dominating two

  11. A comparison of multifractal behavior in galaxy samples from SDSS

    NASA Astrophysics Data System (ADS)

    García-Farieta, J. E.; Casas-Miranda, R. A.

    2017-07-01

    We studied the spatial distribution of galaxies with samples from the Sloan Digital Sky Survey (SDSS) including observational holes in the masks. From a multifractal formalism and using the sliding window technique for each sample, we have determined the fractal dimension and the lacunarity spectrum. Aditionally, the scale of homogeneity was determined for each struture parameter. Our results show that the galaxy clustering exhibits a behavior that depends on the radial distance, revealing that the hierarchical distribution is not a fractal at large-scales, with a transition to homogeneity on large scales below 130 Mpc/h.

  12. Kinematics of early-type galaxies from the Nuker sample

    NASA Astrophysics Data System (ADS)

    Pinkney, J.; Gebhardt, K.; Bender, R.; Richstone, D.; Nuker Team

    2000-05-01

    The Nuker team has STIS Ca triplet spectroscopy of the centers of 10 early-type galaxies. We have measured the first four moments of the losvd's from these data using three techniques: FQ, FCQ and Penalized Maximum Likelihood. To complement the modelling of the stellar orbital structure (Gebhardt, this session), we will compare these moments to other properties of the galaxies. These properties include the ground-based kinematics (e.g., global dispersion) and photometric properties (e.g., bulge luminosity). The sample shows a tendancy toward negative H4 values (i.e., boxy losvd's) near the center. The galaxies that are significantly negative are N3608 and N4473, both of which show signs of merger. We acknowledge support from HST grant GO-07388.01 and LTSA grant NAG5-8238 to D. Richstone.

  13. The AMIGA sample of isolated galaxies. IX. Molecular gas properties

    NASA Astrophysics Data System (ADS)

    Lisenfeld, U.; Espada, D.; Verdes-Montenegro, L.; Kuno, N.; Leon, S.; Sabater, J.; Sato, N.; Sulentic, J.; Verley, S.; Yun, M. S.

    2011-10-01

    Aims: We characterize the molecular gas content (ISM cold phase) using CO emission of a redshift-limited subsample of isolated galaxies from the AMIGA (Analysis of the interstellar Medium of Isolated GAlaxies) project in order to provide a comparison sample for studies of galaxies in different environments. Methods: We present the 12CO(1-0) data for 273 AMIGA galaxies, most of them (n = 186) from our own observations with the IRAM 30 m and the FCRAO 14 m telescopes and the rest from the literature. We constructed a redshift-limited sample containing galaxies with 1500 km s-1 < v < 5000 km s-1 and excluded objects with morphological evidence of possible interaction. This sample (n = 173) is the basis for our statistical analysis. It contains galaxies with molecular gas masses, MH2, in the range of ~108 - 1010 M⊙. It is dominated, both in absolute number and in detection rate, by spiral galaxies of type T = 3-5 (Sb-Sc). Most galaxies were observed with a single pointing towards their centers. Therefore, we performed an extrapolation to the total molecular gas mass expected in the entire disk based on the assumption of an exponential distribution. We then studied the relationships between MH2 and other galactic properties (LB, D_25^2, LK, LFIR, and MHI). Results: We find correlations between MH2 and LB, D_25^2, LK, and LFIR. The tightest correlation of MH2 holds with LFIR and, for T = 3-5, with LK, and the poorest with D_25^2. The correlations with LFIR and LK are very close to linearity. The correlation with LB is nonlinear so that MH2/LB increases with LB. The molecular and the atomic gas masses of our sample show no strong correlation. We find a low mean value, log(MH2/MHI) = -0.7 (for T = 3-5), and a strong decrease in this ratio with morphological type. The molecular gas column density and the surface density of the star formation rate (the Kennicutt-Schmidt law) show a tight correlation with a rough unity slope. We compare the relations of MH2 with LB and LK

  14. A homogeneous sample of binary galaxies: Basic observational properties

    NASA Technical Reports Server (NTRS)

    Karachentsev, I. D.

    1990-01-01

    A survey of optical characteristics for 585 binary systems, satisfying a condition of apparent isolation on the sky, is presented. Influences of various selection effects distorting the average parameters of the sample are noted. The pair components display mutual similarity over all the global properties: luminosity, diameter, morphological type, mass-to-luminosity ratio, angular momentum etc., which is not due only to selection effects. The observed correlations must be caused by common origin of pair members. Some features (nuclear activity, color index) could acquire similarity during synchronous evolution of double galaxies. Despite the observed isolation, the sample of double systems is seriously contaminated by accidental pairs, and also by members of groups and clusters. After removing false pairs estimates of orbital mass-to-luminosity ratio range from 0 to 30 f(solar), with the mean value (7.8 plus or minus 0.7) f(solar). Binary galaxies possess nearly circular orbits with a typical eccentrity e = 0.25, probably resulting from evolutionary selection driven by component mergers under dynamical friction. The double-galaxy population with space abundance 0.12 plus or minus 0.02 and characteristic merger timescale 0.2 H(exp -1) may significantly influence the rate of dynamical evolution of galaxies.

  15. Analysis of the Einstein sample of early-type galaxies

    NASA Technical Reports Server (NTRS)

    Eskridge, Paul B.; Fabbiano, Giuseppina

    1993-01-01

    The EINSTEIN galaxy catalog contains x-ray data for 148 early-type (E and SO) galaxies. A detailed analysis of the global properties of this sample are studied. By comparing the x-ray properties with other tracers of the ISM, as well as with observables related to the stellar dynamics and populations of the sample, we expect to determine more clearly the physical relationships that determine the evolution of early-type galaxies. Previous studies with smaller samples have explored the relationships between x-ray luminosity (L(sub x)) and luminosities in other bands. Using our larger sample and the statistical techniques of survival analysis, a number of these earlier analyses were repeated. For our full sample, a strong statistical correlation is found between L(sub X) and L(sub B) (the probability that the null hypothesis is upheld is P less than 10(exp -4) from a variety of rank correlation tests. Regressions with several algorithms yield consistent results.

  16. On the fairness of the main galaxy sample of SDSS

    NASA Astrophysics Data System (ADS)

    Meng, Ke-Lai; Ma, Bin; Pan, Jun; Feng, Long-Long

    2011-06-01

    Flux-limited and volume-limited galaxy samples are constructed from the Sloan Digital Sky Survey (SDSS) data releases DR4, DR6 and DR7 for statistical analysis. The two-point correlation functions ξ(s), monopole of three-point correlation functions ζ0, projected two-point correlation function wp and pairwise velocity dispersion σ12 are measured to test if galaxy samples are fair for these statistics. We find that with the increment of sky coverage of subsequent data releases in SDSS, ξ(s) of the flux-limited sample is extremely robust and insensitive to local structures at low redshift. However, for volume-limited samples fainter than L* at large scales s ≳ 10 h-1 Mpc, the deviation of ξ(s) from different SDSS data releases (DR7, DR6 and DR4) increases with the increment of absolute magnitude. The case of ζ0(s) is similar to that of ξ(s). In the weakly nonlinear regime, there is no agreement between ζ0 of different data releases in all luminosity bins. Furthermore, wp of volume-limited samples of DR7 in luminosity bins fainter than -Mr,0.1 = [18.5, 19.5] are significantly larger and σ12 of the two faintest volume-limited samples of DR7 display a very different scale dependence than results from DR4 and DR6. Our findings call for caution in understanding clustering analysis results of SDSS faint galaxy samples and higher order statistics of SDSS volume-limited samples in the weakly nonlinear regime. The first zero-crossing points of ξ(s) from volume-limited samples are also investigated and discussed.

  17. VizieR Online Data Catalog: New sample of bright galaxy pairs in UZC (Focardi+, 2006)

    NASA Astrophysics Data System (ADS)

    Focardi, P.; Zitelli, V.; Marinoni, S.; Kelm, B.

    2006-06-01

    We present a new sample of bright galaxy pairs extracted applying an objective selection code to the UZC catalog. The sample is volume-limited to Mzw=-18.9+5logh and contains 89 galaxy pairs. We analyze the kinematical, morphological, and photometrical properties of galaxies belonging to this sample. (1 data file).

  18. NIR surface photometry of a sample of nearby spiral galaxies

    NASA Astrophysics Data System (ADS)

    Castro-Rodríguez, N.; Garzón, F.

    2003-11-01

    The first results of an observational programme aimed at mapping a sample of face-on spiral galaxies in the NIR are presented. This paper shows the surface photometry of the first ten galaxies in the sample. The data were taken in the broad band J (1.2 mu m) and Ks (2.2 mu m) filters. The sources were selected mainly according to their size and brightness in order to suit the characteristics of the CAIN 2D NIR camera on the 1.5-m Carlos Sánchez Telescope (Tenerife, Spain). The primary scientific goal is to provide a comprehensive and uniform database of the main structural and photometric parameters of the sample members from NIR surface photometry. To this end, elliptical isophotal fitting was performed on each galaxy image to extract information about the size and location of its morphological components and provide the azimuthally averaged radial brightness profile. Analytical functions for each component's brightness distribution were then used to match that profile, and their functional parameters obtained from the global fitting. This first report includes data for NGC 3344, NGC 3686, NGC 3938, NGC 3953, NGC 4254, NGC 4303, NGC 4314, NGC 5248, NGC 6384 and NGC 7479.

  19. THE MULTI-WAVELENGTH EXTREME STARBURST SAMPLE OF LUMINOUS GALAXIES. I. SAMPLE CHARACTERISTICS

    SciTech Connect

    Laag, Edward; Croft, Steve; Canalizo, Gabriela; Lacy, Mark

    2010-12-15

    This paper introduces the Multi-wavelength Extreme Starburst Sample (MESS), a new catalog of 138 star-forming galaxies (0.1 < z < 0.3) optically selected from the Sloan Digital Sky Survey using emission line strength diagnostics to have a high absolute star formation rate (SFR; minimum 11 M{sub sun} yr{sup -1} with median SFR {approx} 61 M{sub sun} yr{sup -1} based on a Kroupa initial mass function). The MESS was designed to complement samples of nearby star-forming galaxies such as the luminous infrared galaxies (LIRGs) and ultraviolet luminous galaxies (UVLGs). Observations using the Multi-band Imaging Photometer (24, 70, and 160 {mu}m channels) on the Spitzer Space Telescope indicate that the MESS galaxies have IR luminosities similar to those of LIRGs, with an estimated median L{sub TIR} {approx} 3 x 10{sup 11} L{sub sun}. The selection criteria for the MESS objects suggest they may be less obscured than typical far-IR-selected galaxies with similar estimated SFRs. Twenty out of 70 of the MESS objects detected in the Galaxy Evolution Explorer FUV band also appear to be UVLGs. We estimate the SFRs based directly on luminosities to determine the agreement for these methods in the MESS. We compare these estimates to the emission line strength technique, since the effective measurement of dust attenuation plays a central role in these methods. We apply an image stacking technique to the Very Large Array FIRST survey radio data to retrieve 1.4 GHz luminosity information for 3/4 of the sample covered by FIRST including sources too faint, and at too high a redshift, to be detected in FIRST. We also discuss the relationship between the MESS objects and samples selected through alternative criteria. Morphologies will be the subject of a forthcoming paper.

  20. Studying the diverse nature of faint galaxies in nearby clusters of the WINGS sample

    NASA Astrophysics Data System (ADS)

    Bettoni, D.; Kjærgaard, P.; Milvang-Jensen, B.; D'Onofrio, M.; Moretti, A.; Poggianti, B. M.; Fasano, G.; Moles, M.

    2011-03-01

    We present the first results of our X-shooter observations for a sample of dwarf (-17 galaxies in nearby (0.04 < z < 0.07) galaxy clusters. This luminosity range is fundamental to trace the evolution of higher-z star-forming cluster galaxies down to the present day, and to explore the galaxy scaling relations of early-type galaxies over a broad mass range. Thanks to high resolution and availability of several lines we can derive the velocity dispersion of the galaxies in this range of luminosities and we begin the construction of the fundamental plane of faint early-type galaxies.

  1. The Herschel Virgo Cluster Survey - VIII. The Bright Galaxy Sample

    NASA Astrophysics Data System (ADS)

    Davies, J. I.; Bianchi, S.; Cortese, L.; Auld, R.; Baes, M.; Bendo, G. J.; Boselli, A.; Ciesla, L.; Clemens, M.; Corbelli, E.; De Looze, I.; di Serego Alighieri, S.; Fritz, J.; Gavazzi, G.; Pappalardo, C.; Grossi, M.; Hunt, L. K.; Madden, S.; Magrini, L.; Pohlen, M.; Smith, M. W. L.; Verstappen, J.; Vlahakis, C.

    2012-02-01

    We describe the Herschel Virgo Cluster Survey and the first data that cover the complete survey area (four 4 × 4 deg2 regions). We use these data to measure and compare the global far-infrared properties of 78 optically bright galaxies that are selected at 500 μm and detected in all five far-infrared bands. We show that our measurements and calibration are broadly consistent with previous data obtained by the IRAS, ISO, Spitzer and Planck. We use SPIRE and PACS photometry data to produce 100-, 160-, 250-, 350- and 500-μm cluster luminosity distributions. These luminosity distributions are not power laws, but 'peaked', with small numbers of both faint and bright galaxies. We measure a cluster 100-500 μm far-infrared luminosity density of 1.6(7.0) ± 0.2 × 109 L⊙ Mpc-3. This compares to a cluster 0.4-2.5 μm optical luminosity density of 5.0(20.0) × 109 L⊙ Mpc-3, some 3.2(2.9) times larger than the far-infrared. A 'typical' photon originates from an optical depth of 0.4 ± 0.1. Most of our sample galaxies are well fitted by a single modified blackbody (β= 2), leading to a mean dust mass of log MDust= 7.31 M⊙ and temperature of 20.0 K. We also derive both stellar and atomic hydrogen masses from which we calculate mean values for the star-to-gas (atomic) and gas (atomic)-to-dust mass ratios of 15.1 and 58.2, respectively. Using our derived dust, atomic gas and stellar masses, we estimate cluster mass densities of 8.6(27.8) × 106, 4.6(13.9) × 108 and 7.8(29.7) × 109 M⊙ Mpc-3 for dust, atomic gas and stars, respectively. These values are higher than those derived for field galaxies by factors of 39(126), 6(18) and 34(129), respectively. In the above, the luminosity/mass densities are given using the whole sample with the values in brackets using just those galaxies that lie between 17 and 23 Mpc. We provide a data table of flux densities in all the Herschel bands for all 78 bright Virgo Cluster galaxies. Herschel is an ESA space observatory with science

  2. The Herschel Fornax Cluster Survey - I. The bright galaxy sample

    NASA Astrophysics Data System (ADS)

    Davies, J. I.; Bianchi, S.; Baes, M.; Boselli, A.; Ciesla, L.; Clemens, M.; Davis, T. A.; De Looze, I.; di Serego Alighieri, S.; Fuller, C.; Fritz, J.; Hunt, L. K.; Serra, P.; Smith, M. W. L.; Verstappen, J.; Vlahakis, C.; Xilouris, E. M.; Bomans, D.; Hughes, T.; Garcia-Appadoo, D.; Madden, S.

    2013-01-01

    We present Herschel Space Telescope observations of the nearby Fornax cluster at 100, 160, 250, 350 and 500 μm with a spatial resolution of 7-36 arcsec (10 arcsec ≈ 1 kpc at dFornax = 17.9 Mpc). We define a sample of 11 bright galaxies, selected at 500 μm, that can be directly compared with our past work on the Virgo cluster. We check and compare our results with previous observations made by IRAS and Planck, finding good agreement. The far-infrared luminosity density is higher, by about a factor of 3, in Fornax compared to Virgo, consistent with the higher number density of galaxies. The 100 μm (42.5-122.5 μm) luminosity is two orders of magnitude larger in Fornax than in the local field as measured by IRAS. We calculate stellar (L0.4-2.5) and far-infrared (L100-500) luminosities for each galaxy and use these to estimate a mean optical depth of τ = 0.4 ± 0.1 - the same value as we previously found for Virgo cluster galaxies. For 10 of the 11 galaxies (NGC 1399 excepted), we fit a modified blackbody curve (β = 2.0) to our observed flux densities to derive dust masses and temperatures of 106.54-8.35 M⊙ and T =14.6-24.2 K, respectively, values comparable to those found for Virgo. The derived stars-to-gas(atomic) and gas(atomic)-to-dust ratios vary from 1.1-67.6 to 9.8-436.5, respectively, again broadly consistent with values for Virgo. Fornax is a mass overdensity in stars and dust of about 120 when compared to the local field (30 for Virgo). Fornax and Virgo are both a factor of 6 lower overdensities in gas(atomic) than in stars and dust indicating loss of gas, but not dust and stars, in the cluster environment. We consider in more detail two of the sample galaxies. As the brightest source in either Fornax or Virgo, NGC 1365 is also detected by Planck. The Planck data fit the PACS/SPIRE spectral energy distribution out to 1382 μm with no evidence of other sources of emission (`spinning dust', free-free, synchrotron). At the opposite end of the scale, NGC

  3. Statistical study of warps in a sample of spiral and lenticular galaxies

    NASA Astrophysics Data System (ADS)

    Hendy, Y. H. M.; Samir, R. M.; Shaker, A. A.; Ibrahim, Alhassan I.

    2016-12-01

    A sample of edge-on (or nearly edge-on) spiral and lenticular galaxies is selected to study the warp phenomenon in their disks. This sample contains 36 disk galaxies selected from Watanabe's catalogue (Watanabe, 1983). We investigate the existence of physical relations between photometric and spectroscopic parameters and the warp degree of galaxies.

  4. Integral field spectroscopy of a sample of nearby galaxies. I. Sample, observations, and data reduction

    NASA Astrophysics Data System (ADS)

    Mármol-Queraltó, E.; Sánchez, S. F.; Marino, R. A.; Mast, D.; Viironen, K.; Gil de Paz, A.; Iglesias-Páramo, J.; Rosales-Ortega, F. F.; Vilchez, J. M.

    2011-10-01

    Aims: Integral field spectroscopy (IFS) is a powerful approach to studying nearby galaxies since it enables a detailed analysis of their resolved physical properties. Here we present our study of a sample of nearby galaxies selected to exploit the two-dimensional information provided by the IFS. Methods: We observed a sample of 48 galaxies from the local universe with the PPaK integral field spectroscopy unit (IFU), of the PMAS spectrograph, mounted at the 3.5 m telescope at Calar Alto Observatory (Almeria, Spain). Two different setups were used during these studies (low - V300 - and medium - V600 - resolution mode) covering a spectral range of around 3700-7000 ÅÅ. We developed a full automatic pipeline for the data reduction, which includes an analysis of the quality of the final data products. We applied a decoupling method to obtain the ionised gas and stellar content of these galaxies, and derive the main physical properties of the galaxies. To assess the accuracy in the measurements of the different parameters, we performed a set of simulations to derive the expected relative errors obtained with these data. In addition, we extracted spectra for two types of aperture, one central and another integrated over the entire galaxy, from the datacubes. The main properties of the stellar populations and ionised gas of these galaxies and an estimate of their relative errors are derived from those spectra, as well as from the whole datacubes. Results: We compare the central spectrum extracted from our datacubes and the SDSS spectrum for each of the galaxies for which this is possible, and find close agreement between the derived values for both samples. We find differences on the properties of galaxies when comparing a central and an integrated spectra, showing the effects of the extracted aperture on the interpretation of the data. Finally, we present two-dimensional maps of some of the main properties derived with the decoupling procedure. Based on observations

  5. Extremely isolated galaxies - I. Sample and simulation analysis

    NASA Astrophysics Data System (ADS)

    Spector, O.; Brosch, N.

    2016-02-01

    We have selected a sample of extremely isolated galaxies (EIGs) from the local Universe (z < 0.024), using a simple isolation criterion: having no known neighbours closer than 300 km s-1(3 h-1 Mpc) in the three-dimensional redshift space (α, δ, z). The sample is unique both in its level of isolation and in the fact that it utilizes H I redshifts from the Arecibo Legacy Fast ALFA (ALFALFA) survey. We analysed the EIG sample using cosmological simulations and found that it contains EIGs with normal mass haloes which have evolved gradually with little or no `major events' (major mergers, or major mass-loss events) in the last 3 Gyr. The fraction of EIGs which deviate from this definition (false positives) is 5-10 per cent. For the general population of dark matter haloes, it was further found that the mass accretion (relative to the current halo mass) is affected by the halo environment mainly through strong interactions with its neighbours. As long as a halo does not experience major events, its mass accretion history does not depend significantly on its environment. `Major events' seem to be the main mechanism that creates low-mass subhaloes (Mhalo < 1010 h- 1 M⊙) that host galaxies (with Mg ≲ -14).

  6. Preliminary results on the study of the environment of a complete sample of Seyfert galaxies

    NASA Astrophysics Data System (ADS)

    Salvato, M.; Rafanelli, P.

    1997-07-01

    The results of the study of the environment of a complete sample of Seyfert galaxies taken from the CfA Redshift Survey (Davis et al. 1983; Huchra et al. 1983) are shown. In particular we compare the distribution of the positions of all galaxies located within five diameters from each Seyfert galaxy of our sample with the analogous distribution observed in a control sample of normal galaxies taken from the Merged Catalogue of Galaxies (hereafter MERCG) (Kogoshvili 1986). This research is based on the analysis of the digitized images of the "Digitized Sky Survey" and on the on--line catalogues APM (Automatic Plate Measuring System) and APS (Automated Plate Scanner).

  7. The Fastest Galaxy Evolution in an Unbiased Compact Group Sample with WISE

    NASA Astrophysics Data System (ADS)

    Lee, Gwang-Ho; Hwang, Ho Seong; Sohn, Jubee; Lee, Myung Gyoon

    2017-02-01

    We study the mid-infrared (MIR) properties of galaxies in compact groups and their environmental dependence using the Wide-field Infrared Survey Explorer (WISE) data. We use a volume-limited sample of 670 compact groups and their 2175 member galaxies with {M}r< -19.77 and 0.01< z< 0.0741, drawn from Sohn et al., which were identified using a friends-of-friends algorithm. Among the 2175 galaxies, 1541 galaxies are detected at WISE 12 μ {{m}} with a signal-to-noise ratio greater than 3. Among the 1541 galaxies, 433 AGN-host galaxies are identified by using both optical and MIR classification schemes. Using the remaining 1108 non-AGN galaxies, we find that the MIR [3.4]–[12] colors of compact group early-type galaxies are on average bluer than those of cluster early-type galaxies. When compact groups have both early- and late-type member galaxies, the MIR colors of the late-type members in those compact groups are bluer than the MIR colors of cluster late-type galaxies. As compact groups are located in denser regions, they tend to have larger early-type galaxy fractions and bluer MIR color galaxies. These trends are also seen for neighboring galaxies around compact groups. However, compact group member galaxies always have larger early-type galaxy fractions and bluer MIR colors than their neighboring galaxies. Our findings suggest that the properties of compact group galaxies depend on both internal and external environments of compact groups, and that galaxy evolution is faster in compact groups than in the central regions of clusters.

  8. The Properties of Faint Galaxies in Nearby Clusters of the WINGS Sample

    NASA Astrophysics Data System (ADS)

    Bettoni, D.; Kjærgaard, P.; Milvan-Jensen, B.; D'Onofrio, M.; Moretti, A.; Poggianti, B. M.; Fasano, G.; Cava, A.; Couch, W.; Fritz, J.; Moles, M.

    We present the results of our X-shooter observations for a sample of dwarf (-17 < MB < -15) galaxies in nearby (0. 040 < z < 0. 068) galaxy clusters of the WINGS sample. The study of galaxies in this faint luminosity range is fundamental to trace the evolution of high-z star-forming cluster galaxies down to the present day. We measure the velocity dispersion of 22 galaxies in this range of luminosity and we explore their scaling relations. We found that the Fundamental Plane has a peculiar feature, suggesting the existence of some kind of warping at low luminosities.

  9. Dynamical Analyses of Galaxy Clusters With Large Redshift Samples

    NASA Astrophysics Data System (ADS)

    Mohr, J. J.; Richstone, D. O.; Wegner, G.

    1998-12-01

    We construct equilibrium models of galaxy orbits in five nearby galaxy clusters to study the distribution of binding mass, the nature of galaxy orbits and the kinematic differences between cluster populations of emission-line and non emission-line galaxies. We avail ourselves of 1718 galaxy redshifts (and 1203 cluster member redshifts) in this Jeans analysis; most of these redshifts are new, coming from multifiber spectroscopic runs on the MDM 2.4m with the Decaspec and queue observing on WIYN with Hydra. In addition to the spectroscopic data we have V and R band CCD mosaics (obtained with the MDM 1.3m) of the Abell region in each of these clusters. Our scientific goals include: (i) a quantitative estimate of the range of binding masses M500 consistent with the optical and X-ray data, (ii) an estimate of the typical galaxy oribital anisotropies required to make the galaxy data consistent with the NFW expectation for the cluster potential, (iii) a better understanding of the systematics inherent in the process of rescaling and ``stacking'' galaxy cluster observations, (iv) a reexamination of the recent CNOC results implying that emission-line (blue) galaxies are an equilibrium population with a more extended radial distribution than their non emission-line (red) galaxy counterparts and (v) a measure of the galaxy contribution to the cluster mass of baryons.

  10. The AMIGA sample of isolated galaxies. XII. Revision of the isolation degree for AMIGA galaxies using the SDSS

    NASA Astrophysics Data System (ADS)

    Argudo-Fernández, M.; Verley, S.; Bergond, G.; Sulentic, J.; Sabater, J.; Fernández Lorenzo, M.; Leon, S.; Espada, D.; Verdes-Montenegro, L.; Santander-Vela, J. D.; Ruiz, J. E.; Sánchez-Expósito, S.

    2013-12-01

    Context. To understand the evolution of galaxies, it is necessary to have a reference sample where the effect of the environment is minimized and quantified. In the framework of the AMIGA project (Analysis of the interstellar Medium of Isolated GAlaxies), we present a revision of the environment for galaxies in the Catalogue of Isolated Galaxies (CIG, Karachentseva 1973, Astrof. Issledovaniia Byu. Spec. Ast. Obs., 8, 3) using the ninth data release of the Sloan Digital Sky Survey (SDSS-DR9). Aims: The aims of this study are to refine the photometric-based AMIGA sample of isolated galaxies and to provide an improvement of the quantification of the isolation degree with respect to previous works, using both photometry and spectroscopy. Methods: We developed an automatic method to search for neighbours within a projected area of 1 Mpc radius centred on each primary galaxy to revise the CIG isolation criteria introduced by Karachentseva (1973). The local number density at the fifth nearest neighbour and the tidal strength affecting the CIG galaxy were estimated to quantify the isolation degree. Results: Of the 636 CIG galaxies considered in the photometric study, 426 galaxies fulfil the CIG isolation criteria within 1 Mpc, taking into account projected neighbours. Of the 411 CIG galaxies considered in the spectroscopic study, 347 galaxies fulfil the CIG isolation criteria when a criterion about redshift difference is added. The available redshifts allow us to reject background neighbours and thus improve the photometric assessment. On average, galaxies in the AMIGA sample show lower values in the local number density and the tidal strength parameters than galaxies in denser environments such as pairs, triplets, compact groups, and clusters. Conclusions: For the first time, the environment and the isolation degree of AMIGA galaxies are quantified using digital data. The use of the SDSS database permits one to identify fainter and smaller-size satellites than in previous

  11. EXTREMELY ISOLATED EARLY-TYPE GALAXIES IN THE SLOAN DIGITAL SKY SURVEY. I. THE SAMPLE

    SciTech Connect

    Fuse, C.; Marcum, P.; Fanelli, M. E-mail: pamela.m.marcum@nasa.gov

    2012-08-15

    We describe the properties of a sample of extremely isolated early-type galaxies (IEGs) selected from the spectroscopic Sloan Digital Sky Survey. Sample galaxies are isolated from nearest neighbors more luminous than M{sub V} = -16.5 by a minimum distance corresponding to 2.5 Mpc and 350 km s{sup -1} in redshift space. The candidate IEGs exhibit a number of unusual features as compared to bulge-dominated galaxies in cluster and group environments, including fainter luminosities, blue colors suggesting possible recent star formation, and smaller physical sizes. The paper is the first in a series analyzing this isolated galaxy sample.

  12. A Survey of a Complete Sample of HII Galaxies to Detect HI Companions

    NASA Astrophysics Data System (ADS)

    Taylor, C. L.; Brinks, E.; Skillman, E. D.

    1993-12-01

    \\HII\\ Galaxies are \\HI\\ rich galaxies which contain one or a few high surface brightness optical knots whose spectra resemble those of \\HII\\ regions. These knots are areas of intense star formation. The current star formation rates are too high to last a Hubble time, leading to the hypothesis that \\HII\\ galaxies undergo star formation in discrete bursts. (Searle & Sargent, 1972, ApJ 173, p. 25) One possible explanation for this phenomenon is that a gravitational interaction triggers the burst of star formation in an otherwise quiescent galaxy. Taylor, Brinks, & Skillman (1993, AJ 105, p. 128) mapped in \\HI\\ 9 isolated \\HII\\ galaxies with the VLA in its most compact configuration. Five \\HI\\ companions were discovered near four of the \\HII\\ galaxies. These \\HI\\ companions were within a radius of 30 arcmin and within 240 \\kms. The companions were typically one order of magnitude smaller than their parent galaxies in both neutral hydrogen and total mass. Motivated by this success, we have obtained 21-cm VLA observations of a complete, volume limited sample of \\HII\\ galaxies without obvious interaction partners. The current sample consists of nineteen members with velocities less than 2500 \\kms. From our observations we have positively identified 10 companions around 8 galaxies, plus a further four sample members which are gravitationaly interacting with nearby sample members, for a total of at least 12 interacting systems. A preliminary analysis of these objects and the statistical significance of the detection rate will be discussed.

  13. Searching for metal-deficient emission-line galaxy candidates: the final sample of the SDSS DR12 galaxies

    NASA Astrophysics Data System (ADS)

    Guseva, N. G.; Izotov, Y. I.; Fricke, K. J.; Henkel, C.

    2017-03-01

    We present a spectroscopic study of metal-deficient dwarf galaxy candidates, selected from the SDSS DR12. The oxygen abundances were derived using the direct method in galaxies with the electron temperature-sensitive emission line [O iii]λ4363 Å measured with an accuracy better than 30%. The oxygen abundances for the remaining galaxies with larger uncertainties of the [O iii]λ4363 Å line fluxes were calculated using a strong-line semi-empirical method by Izotov and Thuan. The resulting sample consists of 287 low-metallicity candidates with oxygen abundances below 12 + log O/H = 7.65 including 23 extremely metal-deficient (XMD) candidates with 12 + log O/H ≤ 7.35. Ten out of sixteen XMDs known so far (or 60%) have been discovered by our team using the direct method. Three XMDs were found in the present study. We study relations between global parameters of low-metallicity galaxies, including absolute optical magnitudes, Hβ luminosities (or equivalently star formation rates), stellar masses, mid-infrared colours, and oxygen abundances. Low-metallicity and XMD galaxies strongly deviate to lower metallicities in L-Z, L(Hβ)-Z and M∗-Z diagrams than in relations obtained for large samples of low-redshift, star-forming galaxies with non-restricted metallicities. These less chemically evolved galaxies with stellar masses ≈106-108M⊙, Hβ luminosities ≈1038-1041 erg s-1, SFR ≈ 0.01-1.0 M⊙ yr-1, and sSFR 50 Gyr-1 have physical conditions which may be characteristic of high-redshift low-mass star-forming galaxies which are still awaiting discovery.

  14. Galaxies

    SciTech Connect

    Not Available

    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.

  15. Exploring cosmic homogeneity with the BOSS DR12 galaxy sample

    NASA Astrophysics Data System (ADS)

    Ntelis, Pierros; Hamilton, Jean-Christophe; Le Goff, Jean-Marc; Burtin, Etienne; Laurent, Pierre; Rich, James; Guillermo Busca, Nicolas; Tinker, Jeremy; Aubourg, Eric; du Mas des Bourboux, Hélion; Bautista, Julian; Palanque Delabrouille, Nathalie; Delubac, Timothée; Eftekharzadeh, Sarah; Hogg, David W.; Myers, Adam; Vargas-Magaña, Mariana; Pâris, Isabelle; Petitjean, Partick; Rossi, Graziano; Schneider, Donald P.; Tojeiro, Rita; Yeche, Christophe

    2017-06-01

    In this study, we probe the transition to cosmic homogeneity in the Large Scale Structure (LSS) of the Universe using the CMASS galaxy sample of BOSS spectroscopic survey which covers the largest effective volume to date, 3 h-3 Gpc3 at 0.43 <= z <= 0.7. We study the scaled counts-in-spheres, N(2.97 for r>RH, we find RH = (63.3±0.7) h-1 Mpc, in agreement at the percentage level with the predictions of the ΛCDM model RH=62.0 h-1 Mpc. Thanks to the large cosmic depth of the survey, we investigate the redshift evolution of the transition to homogeneity scale and find agreement with the ΛCDM prediction. Finally, we find that Script D2 is compatible with 3 at scales larger than 300 h-1 Mpc in all redshift bins. These results consolidate the Cosmological Principle and represent a precise consistency test of the ΛCDM model.

  16. VizieR Online Data Catalog: Sample of Compact Group (CG) galaxies (Scudder+, 2012)

    NASA Astrophysics Data System (ADS)

    Scudder, J. M.; Ellison, S. L.; Mendel, J. T.

    2013-04-01

    We construct a sample of 75863 star-forming galaxies with robust metallicity and star formation rate (SFR) measurements from the Sloan Digital Sky Survey Data Release 7, from which we select a clean sample of compact group (CG) galaxies. The CGs are defined to be close configurations of at least four galaxies that are otherwise apparently isolated. Our selection results in a sample of 112 spectroscopically identified CG galaxies, which can be further divided into groups that are either embedded within a larger structure, such as a cluster or large group, or truly isolated systems. The CGs then serve as a probe into the influence of large-scale environment on a galaxy's evolution, while keeping the local density fixed at high values. W (2 data files).

  17. VizieR Online Data Catalog: LAMOST metal-poor galaxies sample (Gao+, 2017)

    NASA Astrophysics Data System (ADS)

    Gao, Y.-L.; Lian, J.-H.; Kong, X.; Lin, Z.-S.; Hu, N.; Liu, H.-Y.; Wang, E.-C.; Cao, Z.-H.; Hou, Y.-H.; Wang, Y.-F.; Zhang, Y.

    2017-08-01

    Among all galaxies from the LAMOST ExtraGAlactic Surveys (LEGAS), we first select a subsample of metal-poor galaxies with emission line flux ratios [NII]λ6583/Hα<=0.1, which yields 665 galaxies. Among them, we identify 237 objects with [OIII]λ4363 detection at >=3σ. We inspect these 237 objects visually, and find 73 of them are false detections. We also exclude 115 objects that are HI regions in nearby large galaxies using optical images with SDSS SkyServer. Finally, we check the right ascension and declination of the remaining sources, and note that one object was observed twice by LAMOST. We keep the observation that has better spectral quality. As a consequence, our final sample consists of 48 galaxies, making up only 0.05% of all the LAMOST galaxies until DR4 Q2. (1 data file).

  18. Surface photometry of a sample of elliptical and S0 galaxies

    SciTech Connect

    De carvalho, R.R.; Da costa, L.N.; Djorgovski, S. California Institute of Technology, Pasadena )

    1991-08-01

    The results are reported of surface photometry of 38 early-type galaxies, located mainly in the Fornax Cluster. Detailed comparisons with previously published work are given along with internal and external error estimates for all quantities, and some serious systematic discrepancies in the older aperture photometry of some of the galaxies in the present sample are pointed out. 15 refs.

  19. CALIFA: a diameter-selected sample for an integral field spectroscopy galaxy survey

    NASA Astrophysics Data System (ADS)

    Walcher, C. J.; Wisotzki, L.; Bekeraité, S.; Husemann, B.; Iglesias-Páramo, J.; Backsmann, N.; Barrera Ballesteros, J.; Catalán-Torrecilla, C.; Cortijo, C.; del Olmo, A.; Garcia Lorenzo, B.; Falcón-Barroso, J.; Jilkova, L.; Kalinova, V.; Mast, D.; Marino, R. A.; Méndez-Abreu, J.; Pasquali, A.; Sánchez, S. F.; Trager, S.; Zibetti, S.; Aguerri, J. A. L.; Alves, J.; Bland-Hawthorn, J.; Boselli, A.; Castillo Morales, A.; Cid Fernandes, R.; Flores, H.; Galbany, L.; Gallazzi, A.; García-Benito, R.; Gil de Paz, A.; González-Delgado, R. M.; Jahnke, K.; Jungwiert, B.; Kehrig, C.; Lyubenova, M.; Márquez Perez, I.; Masegosa, J.; Monreal Ibero, A.; Pérez, E.; Quirrenbach, A.; Rosales-Ortega, F. F.; Roth, M. M.; Sanchez-Blazquez, P.; Spekkens, K.; Tundo, E.; van de Ven, G.; Verheijen, M. A. W.; Vilchez, J. V.; Ziegler, B.

    2014-09-01

    We describe and discuss the selection procedure and statistical properties of the galaxy sample used by the Calar Alto Legacy Integral Field Area (CALIFA) survey, a public legacy survey of 600 galaxies using integral field spectroscopy. The CALIFA "mother sample" was selected from the Sloan Digital Sky Survey (SDSS) DR7 photometric catalogue to include all galaxies with an r-band isophotal major axis between 45'' and 79.2'' and with a redshift 0.005 < z < 0.03. The mother sample contains 939 objects, 600 of which will be observed in the course of the CALIFA survey. The selection of targets for observations is based solely on visibility and thus keeps the statistical properties of the mother sample. By comparison with a large set of SDSS galaxies, we find that the CALIFA sample is representative of galaxies over a luminosity range of -19 > Mr > -23.1 and over a stellar mass range between 109.7 and 1011.4 M⊙. In particular, within these ranges, the diameter selection does not lead to any significant bias against - or in favour of - intrinsically large or small galaxies. Only below luminosities of Mr = -19 (or stellar masses <109.7 M⊙) is there a prevalence of galaxies with larger isophotal sizes, especially of nearly edge-on late-type galaxies, but such galaxies form <10% of the full sample. We estimate volume-corrected distribution functions in luminosities and sizes and show that these are statistically fully compatible with estimates from the full SDSS when accounting for large-scale structure. For full characterization of the sample, we also present a number of value-added quantities determined for the galaxies in the CALIFA sample. These include consistent multi-band photometry based on growth curve analyses; stellar masses; distances and quantities derived from these; morphological classifications; and an overview of available multi-wavelength photometric measurements. We also explore different ways of characterizing the environments of CALIFA galaxies

  20. Multiwavelength Study of Radio Loud Early-Type Galaxies from the B2 Sample

    NASA Astrophysics Data System (ADS)

    Sahu, Sheetal Kumar; Chaware, Laxmikant; Pandey, S. K.; Kulkarni, Samridhi; Pandge, M. B.; Chakradhari, N. K.

    2014-07-01

    We present multiwavelength study of a sample of radio loud early-type galaxies chosen from the B2 sample. We performed surface photometry in BVR broad band filters and Hα narrow band filter on CCD images of sample galaxies using IGO 2m telescope, Pune (INDIA), to get radial profiles of various photometric and geometrical parameters that describe elliptical isophotes fitted to the 2D light distribution of the galaxies. The analysis of radial profiles of quantities such as the (local) surface brightness, the ellipticity, and the deviations from elliptical isophotes parametrized by the Fourier coefficients are main focus of our study. We generated color maps, residual maps, and dust extinction maps, Hα emission maps of the galaxies to study the morphology of the dust and ionized gas content present in the galaxies. We carried out detailed analysis of the properties of the dust present in our sample galaxies. Additionaly, we investigated properties of the dust in the central ~10 arcsec region of our sample galaxies using optical images available from the HST (WFPC2) data archive. We estimated mass and temperature of the dust, molecular gas mass, in the sample galaxies using FIR fluxes of the galaxies obtained from IRAS. We used spectroscopic data available from the SDSS (DR7) to get an estimate of the mass of the central super massive black-hole for B2 1257+28 (NGC 4874). We plotted rotation curve for coma cluster (Abell 1656), which indicates the presence of dark matter halo around the galaxy B2 1257+28.

  1. The SAGES Legacy Unifying Globulars and GalaxieS Survey (SLUGGS): Sample Definition, Methods, and Initial Results

    NASA Astrophysics Data System (ADS)

    Brodie, Jean P.; Romanowsky, Aaron J.; Strader, Jay; Forbes, Duncan A.; Foster, Caroline; Jennings, Zachary G.; Pastorello, Nicola; Pota, Vincenzo; Usher, Christopher; Blom, Christina; Kader, Justin; Roediger, Joel C.; Spitler, Lee R.; Villaume, Alexa; Arnold, Jacob A.; Kartha, Sreeja S.; Woodley, Kristin A.

    2014-11-01

    We introduce and provide the scientific motivation for a wide-field photometric and spectroscopic chemodynamical survey of nearby early-type galaxies (ETGs) and their globular cluster (GC) systems. The SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey is being carried out primarily with Subaru/Suprime-Cam and Keck/DEIMOS. The former provides deep gri imaging over a 900 arcmin2 field-of-view to characterize GC and host galaxy colors and spatial distributions, and to identify spectroscopic targets. The NIR Ca II triplet provides GC line-of-sight velocities and metallicities out to typically ~8 R e, and to ~15 R e in some cases. New techniques to extract integrated stellar kinematics and metallicities to large radii (~2-3 R e) are used in concert with GC data to create two-dimensional (2D) velocity and metallicity maps for comparison with simulations of galaxy formation. The advantages of SLUGGS compared with other, complementary, 2D-chemodynamical surveys are its superior velocity resolution, radial extent, and multiple halo tracers. We describe the sample of 25 nearby ETGs, the selection criteria for galaxies and GCs, the observing strategies, the data reduction techniques, and modeling methods. The survey observations are nearly complete and more than 30 papers have so far been published using SLUGGS data. Here we summarize some initial results, including signatures of two-phase galaxy assembly, evidence for GC metallicity bimodality, and a novel framework for the formation of extended star clusters and ultracompact dwarfs. An integrated overview of current chemodynamical constraints on GC systems points to separate, in situ formation modes at high redshifts for metal-poor and metal-rich GCs.

  2. Complete identification of the Parkes half-Jansky sample of GHz peaked spectrum radio galaxies

    NASA Astrophysics Data System (ADS)

    de Vries, N.; Snellen, I. A. G.; Schilizzi, R. T.; Lehnert, M. D.; Bremer, M. N.

    2007-03-01

    Context: Gigahertz Peaked Spectrum (GPS) radio galaxies are generally thought to be the young counterparts of classical extended radio sources. Statistically complete samples of GPS sources are vital for studying the early evolution of radio-loud AGN and the trigger of their nuclear activity. The "Parkes half-Jansky" sample of GPS radio galaxies is such a sample, representing the southern counterpart of the 1998 Stanghellini sample of bright GPS sources. Aims: As a first step of the investigation of the sample, the host galaxies need to be identified and their redshifts determined. Methods: Deep R-band VLT-FORS1 and ESO 3.6 m EFOSC II images and long slit spectra have been taken for the unidentified sources in the sample. Results: We have identified all twelve previously unknown host galaxies of the radio sources in the sample. Eleven have host galaxies in the range 21.0 < RC < 23.0, while one object, PKS J0210+0419, is identified in the near infrared with a galaxy with Ks = 18.3. The redshifts of 21 host galaxies have been determined in the range 0.474 < z < 1.539, bringing the total number of redshifts to 39 (80%). Analysis of the absolute magnitudes of the GPS host galaxies show that at z>1 they are on average a magnitude fainter than classical 3C radio galaxies, as found in earlier studies. However their restframe UV luminosities indicate that there is an extra light contribution from the AGN, or from a population of young stars. Based on observations collected at the European Southern Observatory Very Large Telescope, Paranal, Chile (ESO prog. ID No. 073.B-0289(B)) and the European Southern Observatory 3.6 m Telescope, La Silla, Chile (prog. ID No. 073.B-0289(A)). Appendices are only available in electronic form at http://www.aanda.org

  3. The Ultraviolet and Infrared Star Formation Rates of Compact Group Galaxies: An Expanded Sample

    NASA Technical Reports Server (NTRS)

    Lenkic, Laura; Tzanavaris, Panayiotis; Gallagher, Sarah C.; Desjardins, Tyler D.; Walker, Lisa May; Johnson, Kelsey E.; Fedotov, Konstantin; Charlton, Jane; Cardiff, Ann H.; Durell, Pat R.

    2016-01-01

    Compact groups of galaxies provide insight into the role of low-mass, dense environments in galaxy evolution because the low velocity dispersions and close proximity of galaxy members result in frequent interactions that take place over extended time-scales. We expand the census of star formation in compact group galaxies by Tzanavaris et al. (2010) and collaborators with Swift UVOT, Spitzer IRAC and MIPS 24 m photometry of a sample of 183 galaxies in 46 compact groups. After correcting luminosities for the contribution from old stellar populations, we estimate the dust-unobscured star formation rate (SFRUV) using the UVOT uvw2 photometry. Similarly, we use the MIPS 24 m photometry to estimate the component of the SFR that is obscured by dust (SFRIR). We find that galaxies which are MIR-active (MIR-red), also have bluer UV colours, higher specific SFRs, and tend to lie in Hi-rich groups, while galaxies that are MIR-inactive (MIR-blue) have redder UV colours, lower specific SFRs, and tend to lie in Hi-poor groups. We find the SFRs to be continuously distributed with a peak at about 1 M yr1, indicating this might be the most common value in compact groups. In contrast, the specific SFR distribution is bimodal, and there is a clear distinction between star-forming and quiescent galaxies. Overall, our results suggest that the specific SFR is the best tracer of gas depletion and galaxy evolution in compact groups.

  4. Sampling Studies Of Quasars, Radio-loud Galaxies, & Radio-quiet Galaxies -- Searching For The Cause Of Radio Emission

    NASA Astrophysics Data System (ADS)

    Coldwell, G.; Salois, Amee; Soechting, I.; Smith, M.

    2011-01-01

    Comparing the environments of Radio-Loud Galaxies, Radio-Quiet Galaxies, and Quasars offers an opportunity to study the evolution of these objects. Our samples have been carefully chosen from Data Release 7 of the Sloan Digital Sky Survey, which also includes samples studied in the FIRST survey, and have been cut to determine the best possible results. Our study includes three samples. The Quasar sample currently contains 69 objects, the Radio-Loud Galaxy (RLG) sample has 1,335 objects, and the Radio-Quiet Galaxy (RQG) sample contains 2,436 objects (any updates will be given at the meeting). A number of trims were made to produce (smaller) samples with characteristics suited for precise results. By comparing the environments of these three samples we will be able to see any similarities or differences between them. If similarities are detected it suggests that the central object has evolved according to 'nature' - in an isolated manner with little environmental feedback, which may or may not have an effect on its evolution, as supposed by Coldwell et al. (2009). If differences are detected it suggests that the central object has evolved according to `nurture’ and that the environment may have played an important role in the development of their properties. We employ similar procedures used by Coldwell et al. (2009) in their study of blue and red AGNs. Upon the completion of an accurate sample, future work will be pursued studying a number of properties of the environments including studies of: the stellar masses, star formation rates, sersic morphologies, as well as densities and ages of the environments.

  5. A Survey of a Complete Sample of HII Galaxies to Detect HI Companions

    NASA Astrophysics Data System (ADS)

    Taylor, C. L.; Skillman, E. D.; Brinks, E.

    1992-12-01

    HII Galaxies are HI rich galaxies which contain one or a few high surface brightness optical knots whose spectra resemble those of HII regions. These knots are areas of intense star formation. The current star formation rates are too high to last a Hubble time, leading to the hypothesis that HII galaxies undergo star formation in discrete bursts. One possible explanation for this phenomenon is that a gravitational interaction triggers the burst of star formation in an otherwise quiescent galaxy. Taylor, Brinks, and Skillman (1993, AJ in press) mapped in HI 9 isolated HII galaxies with the VLA in its most compact configuration. Five HI companions were discovered near four of the HII galaxies. These HI companions were within a radius of 30 arcmin and within 240 km/s. The companions were typically one order of magnitude smaller than their parent galaxies in both neutral hydrogen and total mass. Motivated by this success, we have obtained 21-cm VLA observations of a complete, volume limited sample of HII galaxies without obvious interaction partners. The current sample consists of nineteen members with velocities less than 2500 km/s. From our observations we have positively identified five companions, and are investigating seven more potential detections. A preliminary analysis of the these objects, and the statistical significance of the detection rate, are presented.

  6. A multiwavelength study of the IRAS Deep Survey galaxy sample. III. Spectral classification and dynamical properties

    NASA Astrophysics Data System (ADS)

    Bettoni, D.; Mazzei, P.; Della Valle, A.

    2012-02-01

    Context. The infrared deep sample (IDS), in the north ecliptical polar region (NEPR), is the first complete, far-IR selected sample, on which numerous studies of galaxy evolution are based. Such a sample allows direct investigation of the evolution of dusty galaxies up to a redshift of about 0.3, where the global star formation rate is known to evolve very fast. As discussed in previous papers, we performed optical and IR (ISOCAM, 15 μm,) follow-up of its galaxies and exploited our IR observations to correct the 60 μm fluxes for confusion effects and observational biases. In them we found indications of a significant incompleteness of IDS sample below S(60) ≃ 80 mJy. We constructed 15 μm and far-IR (60 μm) luminosity functions of a complete sample of 56 ISO/IRAS sources. Aims: Here we present and analyze the spectral classification of several galaxies in the IDS sample together with rotation curves which allow estimating the lower mass limits of a subsample of objects. Methods: We measured fluxes and intensity ratios of the emission lines in the visible region of the spectrum (λ4000-9000 Å) for 75 galaxy members. Moreover, for some of them (55%), the spectra obtained with the Keck II telescope have sufficient wavelength and spatial resolution to derive their rotation curve. Results: These galaxies turn out to be disk like systems, with a high fraction (~50%) of interacting systems. The spectroscopic classification of 42 galaxies, using the emission-line ratio diagnostic diagrams, shows that the NEPR sample is predominantly composed of starburst galaxies (71%), while the fraction of AGNs (7%) and LINERs (21%) is small. The dynamical analysis allows us to estimate the lower mass limits of 39 galaxies. Conclusions: The rest-frame FIR luminosity distribution of these galaxies spans the same range as that of the FIR selected complete sample, i.e. three orders of magnitude, with the same mean value, log(LFIR) = 10.2. This emphasizes that such galaxies represent

  7. Barred Galaxy Photometry: Comparing results from the Cananea sample with N-body simulations

    NASA Astrophysics Data System (ADS)

    Athanassoula, E.; Gadotti, D. A.; Carrasco, L.; Bosma, A.; de Souza, R. E.; Recillas, E.

    2009-11-01

    We compare the results of the photometrical analysis of barred galaxies with those of a similar analysis from N-body simulations. The photometry is for a sample of nine barred galaxies observed in the J and K[s] bands with the CANICA near infrared (NIR) camera at the 2.1 m telescope of the Observatorio Astrofísico Guillermo Haro (OAGH) in Cananea, Sonora, Mexico. The comparison includes radial ellipticity profiles and surface brightness (density for the N-body galaxies) profiles along the bar major and minor axes. We find very good agreement, arguing that the exchange of angular momentum within the galaxy plays a determinant role in the evolution of barred galaxies.

  8. Galaxy evolution in a large sample of X-ray clusters

    NASA Astrophysics Data System (ADS)

    Urquhart, Sheona Anne

    It is long established that the evolution of populations of galaxies is dependent upon the environment in which they are located, from low mass galaxy groups to rich galaxy clusters. However, what is not so clear is which physical process(es) dominate this evolution. There are a number of different mechanisms which have been proposed and these can be broadly divided into two categories. There are those caused by interactions with the cluster environment itself (including ram-pressure stripping) and those caused by galaxy-galaxy interactions (including merging events). Disentangling these is a non-trivial task. In this thesis, we use a number of parameters to do so all based upon our uniform CFHT Megacam photometry for X-ray selected galaxy clusters drawn from the X-Ray Multi-Mirror (XMM) Large Scale Structure (LSS) survey and the Canadian Cluster Comparison Project (CCCP). These clusters possess well determined X-ray temperatures spanning the range 1 < kT(keV) < 12 and occupy a relatively narrow redshift interval (0.15 < z < 0.41) in order to minimise any redshift dependent photometric effects. We investigate the colour bimodality of cluster galaxy populations and compute blue fractions using the criteria of Butcher and Oemler (1984) and identify a trend of observing increasing blue fractions versus redshift in common with numerous previous studies. However, we also identify an environmental dependence of cluster blue fraction in that cool (low mass) clusters display higher blue fractions than hotter (higher mass) clusters. Introducing the local galaxy density parameter, Sigma5, we find that there is a greater variation in blue fraction as a function of Sigma 5 in the low mass groups compared to the high mass clusters, but all of our samples (cool, mid and hot temperatures) show a decrease in blue fraction with an increase in local galaxy density, consistent with galaxy-galaxy interactions. We also show that the global cluster environment is playing a role since we

  9. Identifying Extraplanar Diffuse Ionized Gas in a Sample of MaNGA Galaxies

    NASA Astrophysics Data System (ADS)

    Hubbard, Ryan J.; Diamond-Stanic, Aleksandar M.; MaNGA Team

    2016-01-01

    The efficiency with which galaxies convert gas into stars is driven by the continuous cycle of accretion and feedback processes within the circumgalactic medium. Extraplanar diffuse ionized gas (eDIG) can provide insights into the tumultuous processes that govern the evolution of galactic disks because eDIG emission traces both inflowing and outflowing gas. With the help of state-of-the-art, spatially-resolved spectroscopy from MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), we developed a computational method to identify eDIG based on the strength of and spatial extent of optical emission lines for a diverse sample of 550 nearby galaxies. This sample includes roughly half of the MaNGA galaxies that will become publicly available in summer 2016 as part of the Thirteenth Data Release of the Sloan Digital Sky Survey. We identified signatures of eDIG in 8% of the galaxies in this sample, and we found that these signatures are particularly common among galaxies with active star formation and inclination angles >45 degrees. Our analysis of the morphology, incidence, and kinematics of eDIG has important implications for current models of accretion and feedback processes that regulate star formation in galaxies. We acknowledge support from the Astrophysics REU program at the University of Wisconsin-Madison, the National Astronomy Consortium, and The Grainger Foundation.

  10. Low X-Ray Luminosity Galaxy Clusters: Main Goals, Sample Selection, Photometric and Spectroscopic Observations

    NASA Astrophysics Data System (ADS)

    Nilo Castellón, José Luis; Alonso, M. Victoria; García Lambas, Diego; Valotto, Carlos; O'Mill, Ana Laura; Cuevas, Héctor; Carrasco, Eleazar R.; Ramírez, Amelia; Astudillo, José M.; Ramos, Felipe; Jaque Arancibia, Marcelo; Ulloa, Natalie; Órdenes, Yasna

    2016-06-01

    We present our study of 19 low X-ray luminosity galaxy clusters (L{}X ˜ 0.5-45 × 1043 erg s-1), selected from the ROSAT Position Sensitive Proportional Counters Pointed Observations and the revised version of Mullis et al. in the redshift range of 0.16-0.7. This is the introductory paper of a series presenting the sample selection, photometric and spectroscopic observations, and data reduction. Photometric data in different passbands were taken for eight galaxy clusters at Las Campanas Observatory; three clusters at Cerro Tololo Interamerican Observatory; and eight clusters at the Gemini Observatory. Spectroscopic data were collected for only four galaxy clusters using Gemini telescopes. Using the photometry, the galaxies were defined based on the star-galaxy separation taking into account photometric parameters. For each galaxy cluster, the catalogs contain the point-spread function and aperture magnitudes of galaxies within the 90% completeness limit. They are used together with structural parameters to study the galaxy morphology and to estimate photometric redshifts. With the spectroscopy, the derived galaxy velocity dispersion of our clusters ranged from 507 km s-1 for [VMF98]022 to 775 km s-1 for [VMF98]097 with signs of substructure. Cluster membership has been extensively discussed taking into account spectroscopic and photometric redshift estimates. In this sense, members are the galaxies within a projected radius of 0.75 Mpc from the X-ray emission peak and with clustercentric velocities smaller than the cluster velocity dispersion or 6000 km s-1, respectively. These results will be used in forthcoming papers to study, among the main topics, the red cluster sequence, blue cloud and green populations, the galaxy luminosity function, and cluster dynamics.

  11. The far-infrared properties of the CfA galaxy sample. I - The catalog

    NASA Technical Reports Server (NTRS)

    Thuan, T. X.; Sauvage, M.

    1992-01-01

    IRAS flux densities are presented for all galaxies in the Center for Astrophysics magnitude-limited sample (mB not greater than 14.5) detected in the IRAS Faint Source Survey (FSS), a total of 1544 galaxies. The detection rate in the FSS is slightly larger than in the PSC for the long-wavelength 60- and 100-micron bands, but improves by a factor of about 3 or more for the short wavelength 12- and 25-micron bands. This optically selected sample consists of galaxies which are, on average, much less IR-active than galaxies in IR-selected samples. It possesses accurate and complete redshift, morphological, and magnitude information, along with observations at other wavelengths.

  12. High–frequency cluster radio galaxies: Luminosity functions and implications for SZE–selected cluster samples

    DOE PAGES

    Gupta, Nikhel; Saro, A.; Mohr, J. J.; ...

    2017-01-15

    We study the overdensity of point sources in the direction of X-ray-selected galaxy clusters from the meta-catalogue of X-ray-detected clusters of galaxies (MCXC; < z > = 0.14) at South Pole Telescope (SPT) and Sydney University Molonglo Sky Survey (SUMSS) frequencies. Flux densities at 95, 150 and 220 GHz are extracted from the 2500 deg2 SPT-SZ survey maps at the locations of SUMSS sources, producing a multifrequency catalogue of radio galaxies. In the direction of massive galaxy clusters, the radio galaxy flux densities at 95 and 150 GHz are biased low by the cluster Sunyaev–Zel’dovich Effect (SZE) signal, which ismore » negative at these frequencies. We employ a cluster SZE model to remove the expected flux bias and then study these corrected source catalogues. We find that the high-frequency radio galaxies are centrally concentrated within the clusters and that their luminosity functions (LFs) exhibit amplitudes that are characteristically an order of magnitude lower than the cluster LF at 843 MHz. We use the 150 GHz LF to estimate the impact of cluster radio galaxies on an SPT-SZ like survey. The radio galaxy flux typically produces a small bias on the SZE signal and has negligible impact on the observed scatter in the SZE mass–observable relation. If we assume there is no redshift evolution in the radio galaxy LF then 1.8 ± 0.7 per cent of the clusters with detection significance ξ ≥ 4.5 would be lost from the sample. As a result, allowing for redshift evolution of the form (1 + z)2.5 increases the incompleteness to 5.6 ± 1.0 per cent. Improved constraints on the evolution of the cluster radio galaxy LF require a larger cluster sample extending to higher redshift.« less

  13. High Frequency Cluster Radio Galaxies: Luminosity Functions and Implications for SZE Selected Cluster Samples

    NASA Astrophysics Data System (ADS)

    Gupta, N.; Saro, A.; Mohr, J. J.; Benson, B. A.; Bocquet, S.; Capasso, R.; Carlstrom, J. E.; Chiu, I.; Crawford, T. M.; de Haan, T.; Dietrich, J. P.; Gangkofner, C.; Holzapfel, W. L.; McDonald, M.; Rapetti, D.; Reichardt, C. L.

    2017-01-01

    We study the overdensity of point sources in the direction of X-ray-selected galaxy clusters from the Meta-Catalog of X-ray detected Clusters of galaxies (MCXC; = 0.14) at South Pole Telescope (SPT) and Sydney University Molonglo Sky Survey (SUMSS) frequencies. Flux densities at 95, 150 and 220 GHz are extracted from the 2500 deg2 SPT-SZ survey maps at the locations of SUMSS sources, producing a multi-frequency catalog of radio galaxies. In the direction of massive galaxy clusters, the radio galaxy flux densities at 95 and 150 GHz are biased low by the cluster Sunyaev-Zel'dovich Effect (SZE) signal, which is negative at these frequencies. We employ a cluster SZE model to remove the expected flux bias and then study these corrected source catalogs. We find that the high frequency radio galaxies are centrally concentrated within the clusters and that their luminosity functions (LFs) exhibit amplitudes that are characteristically an order of magnitude lower than the cluster LF at 843 MHz. We use the 150 GHz LF to estimate the impact of cluster radio galaxies on an SPT-SZ like survey. The radio galaxy flux typically produces a small bias on the SZE signal and has negligible impact on the observed scatter in the SZE mass-observable relation. If we assume there is no redshift evolution in the radio galaxy LF then 1.8 ± 0.7 percent of the clusters with detection significance ξ ≥ 4.5 would be lost from the sample. Allowing for redshift evolution of the form (1 + z)2.5 increases the incompleteness to 5.6 ± 1.0 percent. Improved constraints on the evolution of the cluster radio galaxy LF require a larger cluster sample extending to higher redshift.

  14. High-frequency cluster radio galaxies: luminosity functions and implications for SZE-selected cluster samples

    NASA Astrophysics Data System (ADS)

    Gupta, N.; Saro, A.; Mohr, J. J.; Benson, B. A.; Bocquet, S.; Capasso, R.; Carlstrom, J. E.; Chiu, I.; Crawford, T. M.; de Haan, T.; Dietrich, J. P.; Gangkofner, C.; Holzapfel, W. L.; McDonald, M.; Rapetti, D.; Reichardt, C. L.

    2017-05-01

    We study the overdensity of point sources in the direction of X-ray-selected galaxy clusters from the meta-catalogue of X-ray-detected clusters of galaxies (MCXC; = 0.14) at South Pole Telescope (SPT) and Sydney University Molonglo Sky Survey (SUMSS) frequencies. Flux densities at 95, 150 and 220 GHz are extracted from the 2500 deg2 SPT-SZ survey maps at the locations of SUMSS sources, producing a multifrequency catalogue of radio galaxies. In the direction of massive galaxy clusters, the radio galaxy flux densities at 95 and 150 GHz are biased low by the cluster Sunyaev-Zel'dovich Effect (SZE) signal, which is negative at these frequencies. We employ a cluster SZE model to remove the expected flux bias and then study these corrected source catalogues. We find that the high-frequency radio galaxies are centrally concentrated within the clusters and that their luminosity functions (LFs) exhibit amplitudes that are characteristically an order of magnitude lower than the cluster LF at 843 MHz. We use the 150 GHz LF to estimate the impact of cluster radio galaxies on an SPT-SZ like survey. The radio galaxy flux typically produces a small bias on the SZE signal and has negligible impact on the observed scatter in the SZE mass-observable relation. If we assume there is no redshift evolution in the radio galaxy LF then 1.8 ± 0.7 per cent of the clusters with detection significance ξ ≥ 4.5 would be lost from the sample. Allowing for redshift evolution of the form (1 + z)2.5 increases the incompleteness to 5.6 ± 1.0 per cent. Improved constraints on the evolution of the cluster radio galaxy LF require a larger cluster sample extending to higher redshift.

  15. An X-ray survey of a complete sample of 3CR radio galaxies

    NASA Technical Reports Server (NTRS)

    Fabbiano, G.; Trinchieri, G.; Elvis, M.; Miller, L.; Longair, M.

    1984-01-01

    The X-ray survey of the galaxies, 40 in all, was made with the Einstein Observatory. By comparing the distributions of X-ray luminosities, it is found that 3CR galaxies with double radio morphology (FR 2) and optical emission-line spectra tend to be the more powerful X-ray emitters, with broad-line galaxies at the top of the distribution. It is also found that the X-ray luminosity is strongly correlated with the 5 GHz radio nuclear luminosity. Through an analysis of the complete optical and radio sample with the Spearman partial rank correlation technique, it is determined that nuclear radio luminosity at 5 GHz is correlated with both total radio luminosity at 178 MHz and with galaxy optical luminosity. Other weaker correlations are found of the X-ray luminosity with the total radio luminosity at 178 MHz and the optical luminosity of the galaxy. The results are seen as underlining the importance of nuclear phenomena in radio galaxies and indicating a nuclear origin of their X-ray emission. In addition, it is found that the 3CR emission-line galaxies are similar to both Seyfert galaxies and quasars with double radio morphology in their X-ray properties, strongly reinforcing a unified picture of active nuclei.

  16. The baryonic Tully-Fisher relation cares about the galaxy sample

    NASA Astrophysics Data System (ADS)

    Sorce, Jenny G.; Guo, Quan

    2016-05-01

    The baryonic Tully-Fisher relation (BTFR) is a clear manifestation of the underlying physics of galaxy formation. As such, it is used to constrain and test galaxy formation and evolution models. Of particular interest, apart from the slope of the relation, is its intrinsic scatter. In this article, we use the EAGLE simulation to study the dependence of the BTFR on the size of the simulated galaxy sample. The huge number of data points available in the simulation is indeed not available with current observations. Observational studies that computed the BTFR used various (small) size samples, with the only obligation to have galaxies spanning a large range of masses and rotation rates. Accordingly, to compare observational and theoretical results, we build a large number of various size data sets using the same criterion and derive the BTFR for all of them. Unmistakably, there is an effect resulting from the number of galaxies used to derive the relation. The smaller the number, the larger the standard deviation around the average slope and intrinsic scatter of a given size sample of galaxies. This observation allows us to alleviate the tensions between observational measurements and ΛCDM predictions. Namely, the size of the observational samples adds up to the complexity in comparing observed and simulated relations to discredit or confirm ΛCDM. Similarly, samples, even large, that do not reflect the galaxy distribution give biased results on average. Large size samples reproducing the underlying distribution of galaxies constitute a supplementary necessity to compare observations and simulations efficiently.

  17. Comparative study of fine structure in samples of isolated and paired early-type galaxies

    NASA Astrophysics Data System (ADS)

    Reduzzi, L.; Longhetti, M.; Rampazzo, R.

    1996-09-01

    Fine structure in early-type galaxies is considered to be among the more robust indicators of a past merging or acquisition event, although growing evidence from numerical simulations suggests that fine structure may be also interpreted in a `weak interaction' framework. We present a morphological study of a sample composed of 61 `isolated' early-type galaxies addressed to the detection of fine structure. This sample has been selected in order to be statistically comparable to a set of 54 early-type galaxies, members of pairs analysed by Reduzzi & Rampazzo with a similar technique. The rate of occurrence of fine structure detected in the `isolated' galaxy sample is significantly higher than that found for the pairs. In particular, the fraction of isolated early-type galaxies exhibiting shells is 16.4 per cent, a percentage similar to that found by Malin & Carter for RC2 isolated objects in the southern sky, while the fraction of early-type galaxies in pairs is ~=4 per cent. We discuss the comparison between the two samples in the context of the merger versus the weak interaction origin of fine structures. Concerning the formation of shells, although the merger origin cannot be ruled out, the observed difference is more naturally explained within the weak interaction framework.

  18. An XMM Survey of a Distance-limited (D < 20Mpc) sample of Seyfert Galaxies

    NASA Astrophysics Data System (ADS)

    Di Cocco, G.; Cappi, M.; Trifoglio, M.; Gianotti, F.; Stephen, J.

    2000-10-01

    ASCA and BeppoSAX results have demonstrated that X-ray Observations of Seyfert galaxies are important to i) verify the predictions and, thus, validity of unified models and ii) understand the origin of the X-ray background. However, average intrinsic properties and "true" column density distribution of Seyfert galaxies obtained from an unbiased sample, the most crucial points in issues i) and ii), are still lacking at present. We therefore show how an XMM study (250 ks awarded in the EPIC GT) on a well-defined, complete, and statistically significant sample of the nearest known 27 Seyfert galaxies could fill this lacuna. Moreover, this study will allow a comprehensive study of the serendipitous source populations in the host galaxies and in the fields.

  19. Multiwavelength Energy Distributions and Bolometric Luminosities of the 12 Micron Galaxy Sample

    NASA Astrophysics Data System (ADS)

    Spinoglio, Luigi; Malkan, Matthew A.; Rush, Brian; Carrasco, Luis; Recillas-Cruz, Elsa

    1995-11-01

    Aperture photometry from our own observations and the literature is presented for the 12 microns galaxies in the near-infrared J, H, and K bands and, in some cases, in the L band. These data are corrected to "total" near-infrared magnitudes (with a typical uncertainty of 0.3 mag) for a direct comparison with our IRAS fluxes which apply to the entire galaxy. The corrected data are used to derive integrated total near-infrared and far-infrared luminosities. We then combine these with blue photometry and an estimate of the flux contribution from cold dust at wavelengths longward of 100 microns to derive the first bolometric luminosities for a large sample of galaxies. The presence of nonstellar radiation at 2-3 microns correlates very well with nonstellar IRAS colors. This enables us to identify a universal Seyfert nuclear continuum from near- to far-infrared wavelengths. Thus, there is a sequence of infrared colors which runs from a pure "normal galaxy" to a pure Seyfert/quasar nucleus. Seyfert 2 galaxies fall close to this same sequence, although only a few extreme narrow-line Seyfert galaxies have quasar-like colors, and these show strong evidence of harboring an obscured broad-line region. A corollary is that the host galaxies of Seyfert nuclei have normal near- to far-infrared spectra on average. Starburst galaxies lie significantly off the sequence, having a relative excess of 60 microns emission probably as a result of stochastically heated dust grains. We use these correlations to identify several combinations of infrared colors which discriminate between Seyfert 1 and 2 galaxies, LINERs, and ultraluminous starbursts. In the infrared, Seyfert 2 galaxies are much more like Seyfert 1s than they are like starbursts, presumably because both kinds of Seyferts are heated by a single central source, rather than a distributed region of star formation. Moreover, combining the [25-2.2 mum] color with the [60-12 mum] color, it appears that Seyfert 1 galaxies are

  20. Constraining CIII] Emission in a Statistic Sample of Five z = 5.7 Galaxies

    NASA Astrophysics Data System (ADS)

    Ding, Jiani; Cai, Zheng; Fan, Xiaohui; Stark, Daniel; Bian, Fuyan; Jiang, Linhua; McGreer, Ian D.; Robertson, Brant E.; Siana, Brian D.; Space Telescope Science Institute

    2017-01-01

    Recent observations have suggested that the CIII]1907/1909 emission line could be an alternative diagnostic line for galaxies in reionization epoch. We use F128N narrowband filter on the Hubble Space Telescope's (HST) Wide Field Camera 3 (WFC3) to search for CIII] emission in a sample of five galaxies at z = 5.7 discovered by Subaru deep fields. Using the F128N narrowband imaging, together with the broadband imaging, we report a 2-sigma signal of CIII] flux of 3.39±1.81x10^(-18) erg/s/cm^(2) in J132416.13+274411.6, the brightest galaxy in our sample (z = 5.7, JAB = 24.1). We do not detect the CIII] for the rest of 4 faint galaxies with JAB ranging from 25 - 27. Using the stacked image, we put a 2-sigma upper limit of 1.66 A on the mean CIII] equivalent width for our sample of galaxies at z = 5.7. Further, we provide the continuum-subtracted narrowband images for each galaxy and we found a 2-sigma residual flux of 3.39±1.81x10^(-18) erg/s/cm^(2) for galaxy J132416.13+274411.6 and put a 2-sigma upper limit of 1.19x10^(-18) erg/s/cm^(2) for the other four faint galaxies (z = 5.7, JAB ranging from 25 - 27). Our observations set an upper limit for CIII] emission at z = 5.7 and could be used as a guide for future observations in the reionization epoch.

  1. The X-Ray Weakness of GPS Radio Galaxies: A Volume-Limited Complete Sample

    NASA Technical Reports Server (NTRS)

    Mushotsky, Richard (Technical Monitor); Siemiginowska, Aneta

    2005-01-01

    The XMM-Newton observations of the GPS sample was completed last summer. We are in process of finalizing the paper describing the data and the results. The main goal of the project was to determine the X-ray spectra of the GPS galaxies in comparison to regular radio galaxies. Our XMM observations show evidence that the GPS galaxies are heavily obscured with the large absorbing columns exceeding N(H)greater than le22 cm^-2. Taking into account the obscuration we determined that the intrinsic X-ray luminosities of GPS galaxies are of order le43-le44 erg/s, comparable to low luminosity radio loud quasars. The large GPS samples can confirm the result, as at this moment our evidence is based only on 7 GPS galaxies observed with good S/N/ in X-rays. The first paper summarizing the results of the XMM observation of Mkn 668 has been published Astronomy & Astrophysics. We found soft X-ray signatures of a hot plasma (kT approximately 10^7K) and a hard X-ray emission from the nucleus. The X-ray spectrum above 2.5-keV is characterized by a very flat (observed photon index, Gamma-0.5) power-law continuum, alongside with a strong Fe-K-alpha neutral iron fluorescent line (EW600-eV). The best explanation for the origin of this high energy X-ray emission is in terms of the Compton-reflection of the nuclear emission. The primary X-ray emission is obscured by a Compton-thick (N_H to 10^24 cm-2) matter which becomes transparent at higher energies. The observed above 2.5-keV X-rays are mostly due to reflection which is indicated by a strong Fe-K-alpha line. This source represented the second hard X-ray detection of the GPS galaxy ever (the first one being 1345+125; O'Dea et al. 2000). The observations of the other GPS galaxies in our sample confirmed the trend of the large obscuration present in the spectra. However, we do not have a compelling evidence for a hot gas in the nucleus. The two other GPS galaxies observed with Chandra were added to the total of 7 GPS galaxies. This GPS

  2. A sample of X-ray emitting normal galaxies from the BMW-HRI Catalogue

    NASA Astrophysics Data System (ADS)

    Tajer, M.; Trinchieri, G.; Wolter, A.; Campana, S.; Moretti, A.; Tagliaferri, G.

    2005-06-01

    We obtained a sample of 143 normal galaxies with X-ray luminosity in the range 1038{-}1043 erg s-1 from the cross-correlation of the ROSAT HRI Brera Multi-scale Wavelet (BMW-HRI) Catalogue with the Lyon-Meudon Extragalactic Database (LEDA). We find that the average X-ray properties of this sample are in good agreement with those of other samples of galaxies in the literature. We selected a complete flux limited serendipitous sample of 32 galaxies from which we derived the log N-log S distribution of normal galaxies in the flux range 1.1{-} 110 × 10-14 erg cm-2 s-1. The resulting distribution is consistent with the Euclidean -1.5 slope. Comparisons with other samples, such as the Extended Medium Sensitivity Survey, the ROSAT All Sky Survey, the XMM-Newton/2dF survey, and the Chandra Deep Field Survey indicate that the log N -log S distribution of normal galaxies is consistent with a Euclidean slope over a flux range of about 6 decades.

  3. Nuclear activity and stellar population of a sample of interacting galaxies

    NASA Astrophysics Data System (ADS)

    Pastoriza, M. G.; Donzelli, C. J.; Bonatto, C.

    1999-07-01

    In this paper we investigate the nuclear activity and stellar population in a sample of 27 physical galaxy pairs. Equivalent widths of absorption features are used to characterise the nuclear stellar population according to templates: most galaxies of the sample have important flux contributions from stars younger than 10(8) years. According to classical diagnostic-diagrams the galaxies in our sample are either classified as H II regions or have emission line ratios near the transition zone between H II regions and LINERs. Based on the observed spectra, only 4 galaxies show LINER properties and 1 nucleus is a Seyfert 2. We found that the spectrum of a transition object (38% of the sample) can be described by a combination of an AGN with an H II region. As a result, 20 galaxies of the present sample may host a low-luminosity active nucleus. Based on observations made at CASLEO and CTIO. Complejo Astronómico El Leoncito (CASLEO) is operated under agreement between the Consejo Nacional de Investigaciones Cient\\'\\i ficas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan.

  4. The ultraviolet and infrared star formation rates of compact group galaxies: an expanded sample

    NASA Astrophysics Data System (ADS)

    Lenkić, Laura; Tzanavaris, Panayiotis; Gallagher, Sarah C.; Desjardins, Tyler D.; Walker, Lisa May; Johnson, Kelsey E.; Fedotov, Konstantin; Charlton, Jane; Hornschemeier, Ann E.; Durrell, Pat R.; Gronwall, Caryl

    2016-07-01

    Compact groups of galaxies provide insight into the role of low-mass, dense environments in galaxy evolution because the low velocity dispersions and close proximity of galaxy members result in frequent interactions that take place over extended time-scales. We expand the census of star formation in compact group galaxies by Tzanavaris et al. (2010) and collaborators with Swift UVOT, Spitzer IRAC and MIPS 24 μm photometry of a sample of 183 galaxies in 46 compact groups. After correcting luminosities for the contribution from old stellar populations, we estimate the dust-unobscured star formation rate (SFRUV) using the UVOT uvw2 photometry. Similarly, we use the MIPS 24 μm photometry to estimate the component of the SFR that is obscured by dust (SFRIR). We find that galaxies which are MIR-active (MIR-`red'), also have bluer UV colours, higher specific SFRs, and tend to lie in H I-rich groups, while galaxies that are MIR-inactive (MIR-`blue') have redder UV colours, lower specific SFRs, and tend to lie in H I-poor groups. We find the SFRs to be continuously distributed with a peak at about 1 M⊙ yr-1, indicating this might be the most common value in compact groups. In contrast, the specific SFR distribution is bimodal, and there is a clear distinction between star-forming and quiescent galaxies. Overall, our results suggest that the specific SFR is the best tracer of gas depletion and galaxy evolution in compact groups.

  5. Redshift-Distance Survey of Early-Type Galaxies. I. Sample Selection, Properties, and Completeness

    NASA Astrophysics Data System (ADS)

    da Costa, L. N.; Bernardi, M.; Alonso, M. V.; Wegner, G.; Willmer, C. N. A.; Pellegrini, P. S.; Rité, C.; Maia, M. A. G.

    2000-07-01

    This is the first in a series of papers describing the recently completed all-sky redshift-distance survey of Early-type NEARby galaxies (ENEAR) carried out for peculiar velocity analysis. The sample is divided into two parts and consists of 1607 elliptical and lenticular galaxies with cz<=7000 km s-1 and with blue magnitudes brighter than mB=14.5 (ENEARm) and of galaxies in clusters (ENEARc). Galaxy distances based on the Dn-σ and fundamental plane (FP) relations are now available for 1359 and 1107 ENEARm galaxies, respectively, with roughly 80% based on new data gathered by our group. The Dn-σ and FP template distance relations are derived by combining 569 and 431 galaxies in 28 clusters, respectively, of which about 60% are based on our new measurements. To date the ENEAR survey has accumulated 2200 R-band images yielding photometric parameters for 1398 galaxies and 2300 spectra yielding 1745 measurements of central velocity dispersions and spectral line indices for 1210 galaxies. In addition, there are some 1834 spectra of early-type galaxies available in the Southern Sky Redshift Survey (SSRS+SSRS2) database, out of which roughly 800 galaxies yield high-quality measurements of velocity dispersions and spectral line indices, bringing the total number of galaxies with available spectral information to about 2000. Combined with measurements publicly available, a catalog has been assembled comprising ~4500 measurements of central velocity dispersions for about 2800 galaxies, ~3700 measurements of photometric parameters for about 2000 galaxies, and distances for about 1900 galaxies. This extensive database provides information on galaxies with multiple observations from different telescope/instrument configurations and from different authors. These overlapping data are used to derive relations to transform all available measurements into a common system, thereby ensuring the homogeneity of the database. The ENEARm redshift-distance survey extends the earlier work

  6. A sample of metal-poor galaxies identified from the LAMOST spectral survey

    NASA Astrophysics Data System (ADS)

    Gao, Yu-Long; Lian, Jian-Hui; Kong, Xu; Lin, Ze-Sen; Hu, Ning; Liu, Hai-Yang; Wang, En-Ci; Cao, Zi-Huang; Hou, Yong-Hui; Wang, Yue-Fei; Zhang, Yong

    2017-04-01

    We present a sample of 48 metal-poor galaxies at z< 0.14 selected from 92 510 galaxies in the LAMOST survey. These galaxies are identified by their detection of the auroral emission line [{{O}} {\\small{{III}}}]λ 4363 above the 3σ level, which allows a direct measurement of electron temperature and oxygen abundance. The emission line fluxes are corrected for internal dust extinction using the Balmer decrement method. With electron temperature derived from [{{O}} {\\small{{III}}}]λ λ 4959,5007/[{{O}} {\\small{{III}}}]λ 4363 and electron density from [{{S}} {\\small{{II}}}]λ 6731/[{{S}} {\\small{{II}}}]λ 6717, we obtain the oxygen abundances in our sample which range from 12+{log}({{O}}/{{H}})=7.63(0.09 {Z}⊙ ) to 8.46 (0.6 {Z}⊙ ). We find an extremely metal-poor galaxy with 12+{log}({{O}}/{{H}})=7.63+/- 0.01. With multiband photometric data from FUV to NIR and {{H}}α measurements, we also determine the stellar masses and star formation rates, based on the spectral energy distribution fitting and {{H}}α luminosity, respectively. We find that our galaxies have low and intermediate stellar masses with 6.39≤ {log}(M/{M}⊙ )≤ 9.27, and high star formation rates (SFRs) with -2.18≤ {log}({SFR}/{M}⊙ {{yr}}-1)≤ 1.95. We also find that the metallicities of our galaxies are consistent with the local {T}{{e}}-based mass-metallicity relation, while the scatter is about 0.28 dex. Additionally, assuming the coefficient of α =0.66, we find most of our galaxies follow the local mass-metallicity-SFR relation, but a scatter of about 0.24 dex exists, suggesting the mass-metallicity relation is weakly dependent on SFR for those metal-poor galaxies.

  7. Redshift-Distance Survey of Early-Type Galaxies. I. The ENEARc Cluster Sample

    NASA Astrophysics Data System (ADS)

    Bernardi, M.; Alonso, M. V.; da Costa, L. N.; Willmer, C. N. A.; Wegner, G.; Pellegrini, P. S.; Rité, C.; Maia, M. A. G.

    2002-06-01

    This paper presents data on the ENEARc subsample of the larger ENEAR survey of nearby early-type galaxies. The ENEARc galaxies belong to clusters and were specifically chosen to be used for the construction of a Dn-σ template. The ENEARc sample includes new measurements of spectroscopic and photometric parameters (redshift, velocity dispersion, line index Mg2, and the angular diameter dn), as well as data from the literature. New spectroscopic data are given for 229 cluster early-type galaxies, and new photometry is presented for 348 objects. Repeat and overlap observations with external data sets are used to construct a final merged catalog consisting of 640 early-type galaxies in 28 clusters. Objective criteria, based on catalogs of groups of galaxies derived from complete redshift surveys of the nearby universe, are used to assign galaxies to clusters. In a companion paper, these data are used to construct the template Dn-σ distance relation for early-type galaxies, which has been used to estimate galaxy distances and derive peculiar velocities for the ENEAR all-sky sample. Based on observations at Complejo Astronomico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan; Cerro Tololo Inter-American Observatory, National Optical Astronomical Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation; the European Southern Observatory (ESO), partially under the ESO-ON agreement; the Fred Lawrence Whipple Observatory; the Observatório do Pico dos Dias, operated by the Laboratório Nacional de Astrofísica and the MDM Observatory at Kitt Peak.

  8. Constraining C iii] Emission in a Sample of Five Luminous z = 5.7 Galaxies

    NASA Astrophysics Data System (ADS)

    Ding, Jiani; Cai, Zheng; Fan, Xiaohui; Stark, Daniel P.; Bian, Fuyan; Jiang, Linhua; McGreer, Ian D.; Robertson, Brant E.; Siana, Brian

    2017-04-01

    Recent observations have suggested that the C iii]λ 1907/1909 emission lines could be alternative diagnostic lines for galaxies in the reionization epoch. We use the F128N narrowband filter on the Hubble Space Telescope’s (HST) Wide Field Camera 3 (WFC3) to search for C iii] emission in a sample of five galaxies at z = 5.7 in the Subaru Deep Field and the Subaru/XMM-Newton Deep Field. Using the F128N narrowband imaging, together with the broadband imaging, we do not detect C iii] emission for the five galaxies with {J}{AB} ranging from 24.10 to 27.00 in our sample. For the brightest galaxy J132416.13+274411.6 in our sample (z = 5.70, {J}{AB}=24.10), which has a significantly higher signal to noise, we report a C iii] flux of 3.34+/- 1.81× {10}-18 {erg} {{{s}}}-1 {{cm}}-2, which places a stringent 3σ upper limit of 5.43× {10}-18 {erg} {{{s}}}-1 {{cm}}-2 on C iii] flux and 6.57 Å on the C iii] equivalent width. Using the stacked image, we put a 3σ upper limit on the mean C iii] flux of 2.55× {10}-18 {erg} {{{s}}}-1 {{cm}}-2 and a 3σ upper limit on the mean C iii] equivalent width of 4.20 Å for this sample of galaxies at z = 5.70. Combined with strong C iii] detection reported among high-z galaxies in the literature, our observations suggest that the equivalent widths of C iii] from galaxies at z > 5.70 exhibit a wide range of distribution. Our strong limits on C iii] emission could be used as a guide for future observations in the reionization epoch.

  9. HICOSMO - cosmology with a complete sample of galaxy clusters - I. Data analysis, sample selection and luminosity-mass scaling relation

    NASA Astrophysics Data System (ADS)

    Schellenberger, G.; Reiprich, T. H.

    2017-08-01

    The X-ray regime, where the most massive visible component of galaxy clusters, the intracluster medium, is visible, offers directly measured quantities, like the luminosity, and derived quantities, like the total mass, to characterize these objects. The aim of this project is to analyse a complete sample of galaxy clusters in detail and constrain cosmological parameters, like the matter density, Ωm, or the amplitude of initial density fluctuations, σ8. The purely X-ray flux-limited sample (HIFLUGCS) consists of the 64 X-ray brightest galaxy clusters, which are excellent targets to study the systematic effects, that can bias results. We analysed in total 196 Chandra observations of the 64 HIFLUGCS clusters, with a total exposure time of 7.7 Ms. Here, we present our data analysis procedure (including an automated substructure detection and an energy band optimization for surface brightness profile analysis) that gives individually determined, robust total mass estimates. These masses are tested against dynamical and Planck Sunyaev-Zeldovich (SZ) derived masses of the same clusters, where good overall agreement is found with the dynamical masses. The Planck SZ masses seem to show a mass-dependent bias to our hydrostatic masses; possible biases in this mass-mass comparison are discussed including the Planck selection function. Furthermore, we show the results for the (0.1-2.4) keV luminosity versus mass scaling relation. The overall slope of the sample (1.34) is in agreement with expectations and values from literature. Splitting the sample into galaxy groups and clusters reveals, even after a selection bias correction, that galaxy groups exhibit a significantly steeper slope (1.88) compared to clusters (1.06).

  10. Inner and outer star forming regions over the discs of spiral galaxies I. Sample characterization

    NASA Astrophysics Data System (ADS)

    Rodríguez-Baras, Marina; Díaz, A. I.; Rosales-Ortega, F. F.

    2017-03-01

    This project is aimed at understanding the dependence of star formation on the environment by analysing young stellar populations in two very different positions in disk galaxies: circumnuclear and outer disk giant regions. Integral field spectroscopy (IFS) provide an ideal means to achieve these goals providing simultaneous spatial and spectral resolution. Here we present the characterization of the work sample, composed by 671 outer regions and 725 inner regions from 263 isolated spirals galaxies observed by the CALIFA survey. The wide number of regions in both samples allows us to obtain statistically relevant results about the influence of metallicity, density and environment on star formation, and how it disseminates over the galaxy, to obtain evolutionary stories for the star-forming regions and to compare our results with models of massive star formation and galactic chemical evolution.

  11. SDSS-IV MaNGA: faint quenched galaxies - I. Sample selection and evidence for environmental quenching

    NASA Astrophysics Data System (ADS)

    Penny, Samantha J.; Masters, Karen L.; Weijmans, Anne-Marie; Westfall, Kyle B.; Bershady, Matthew A.; Bundy, Kevin; Drory, Niv; Falcón-Barroso, Jesús; Law, David; Nichol, Robert C.; Thomas, Daniel; Bizyaev, Dmitry; Brownstein, Joel R.; Freischlad, Gordon; Gaulme, Patrick; Grabowski, Katie; Kinemuchi, Karen; Malanushenko, Elena; Malanushenko, Viktor; Oravetz, Daniel; Roman-Lopes, Alexandre; Pan, Kaike; Simmons, Audrey; Wake, David A.

    2016-11-01

    Using kinematic maps from the Sloan Digital Sky Survey (SDSS) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, we reveal that the majority of low-mass quenched galaxies exhibit coherent rotation in their stellar kinematics. Our sample includes all 39 quenched low-mass galaxies observed in the first year of MaNGA. The galaxies are selected with Mr > -19.1, stellar masses 109 M⊙ < M* < 5 × 109 M⊙, EWHα < 2 Å, and all have red colours (u - r) > 1.9. They lie on the size-magnitude and σ-luminosity relations for previously studied dwarf galaxies. Just six (15 ± 5.7 per cent) are found to have rotation speeds ve, rot < 15 km s-1 at ˜1 Re, and may be dominated by pressure support at all radii. Two galaxies in our sample have kinematically distinct cores in their stellar component, likely the result of accretion. Six contain ionized gas despite not hosting ongoing star formation, and this gas is typically kinematically misaligned from their stellar component. This is the first large-scale Integral Field Unit (IFU) study of low-mass galaxies selected without bias against low-density environments. Nevertheless, we find the majority of these galaxies are within ˜1.5 Mpc of a bright neighbour (MK < -23; or M* > 5 × 1010 M⊙), supporting the hypothesis that galaxy-galaxy or galaxy-group interactions quench star formation in low-mass galaxies. The local bright galaxy density for our sample is ρproj = 8.2 ± 2.0 Mpc-2, compared to ρproj = 2.1 ± 0.4 Mpc-2 for a star-forming comparison sample, confirming that the quenched low-mass galaxies are preferentially found in higher density environments.

  12. Updated 34-band Photometry for the Sings/KINGFISH Samples of Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Dale, D. A.; Cook, D. O.; Roussel, H.; Turner, J. A.; Armus, L.; Bolatto, A. D.; Boquien, M.; Brown, M. J. I.; Calzetti, D.; De Looze, I.; Galametz, M.; Gordon, K. D.; Groves, B. A.; Jarrett, T. H.; Helou, G.; Herrera-Camus, R.; Hinz, J. L.; Hunt, L. K.; Kennicutt, R. C.; Murphy, E. J.; Rest, A.; Sandstrom, K. M.; Smith, J.-D. T.; Tabatabaei, F. S.; Wilson, C. D.

    2017-03-01

    We present an update to the ultraviolet-to-radio database of global broadband photometry for the 79 nearby galaxies that comprise the union of the KINGFISH (Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel) and SINGS (Spitzer Infrared Nearby Galaxies Survey) samples. The 34-band data set presented here includes contributions from observational work carried out with a variety of facilities including GALEX, SDSS, Pan-STARRS1, NOAO, 2MASS, Wide-Field Infrared Survey Explorer, Spitzer, Herschel, Planck, JCMT, and the VLA. Improvements of note include recalibrations of previously published SINGS BVR C I C and KINGFISH far-infrared/submillimeter photometry. Similar to previous results in the literature, an excess of submillimeter emission above model predictions is seen primarily for low-metallicity dwarf or irregular galaxies. This 33-band photometric data set for the combined KINGFISH+SINGS sample serves as an important multiwavelength reference for the variety of galaxies observed at low redshift. A thorough analysis of the observed spectral energy distributions is carried out in a companion paper.

  13. HICOSMO: cosmology with a complete sample of galaxy clusters - II. Cosmological results

    NASA Astrophysics Data System (ADS)

    Schellenberger, G.; Reiprich, T. H.

    2017-10-01

    The X-ray bright, hot gas in the potential well of a galaxy cluster enables systematic X-ray studies of samples of galaxy clusters to constrain cosmological parameters. HIFLUGCS consists of the 64 X-ray brightest galaxy clusters in the Universe, building up a local sample. Here, we utilize this sample to determine, for the first time, individual hydrostatic mass estimates for all the clusters of the sample and, by making use of the completeness of the sample, we quantify constraints on the two interesting cosmological parameters, Ωm and σ8. We apply our total hydrostatic and gas mass estimates from the X-ray analysis to a Bayesian cosmological likelihood analysis and leave several parameters free to be constrained. We find Ωm = 0.30 ± 0.01 and σ8 = 0.79 ± 0.03 (statistical uncertainties, 68 per cent credibility level) using our default analysis strategy combining both a mass function analysis and the gas mass fraction results. The main sources of biases that we correct here are (1) the influence of galaxy groups (incompleteness in parent samples and differing behaviour of the Lx-M relation), (2) the hydrostatic mass bias, (3) the extrapolation of the total mass (comparing various methods), (4) the theoretical halo mass function and (5) other physical effects (non-negligible neutrino mass). We find that galaxy groups introduce a strong bias, since their number density seems to be over predicted by the halo mass function. On the other hand, incorporating baryonic effects does not result in a significant change in the constraints. The total (uncorrected) systematic uncertainties (∼20 per cent) clearly dominate the statistical uncertainties on cosmological parameters for our sample.

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

    NASA Technical Reports Server (NTRS)

    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.

  15. GMASS ultradeep spectroscopy of galaxies at z ~ 2. VII. Sample selection and spectroscopy

    NASA Astrophysics Data System (ADS)

    Kurk, J.; Cimatti, A.; Daddi, E.; Mignoli, M.; Pozzetti, L.; Dickinson, M.; Bolzonella, M.; Zamorani, G.; Cassata, P.; Rodighiero, G.; Franceschini, A.; Renzini, A.; Rosati, P.; Halliday, C.; Berta, S.

    2013-01-01

    Context. Ultra-deep imaging of small parts of the sky has revealed many populations of distant galaxies, providing insight into the early stages of galaxy evolution. Spectroscopic follow-up has mostly targeted galaxies with strong emission lines at z > 2 or concentrated on galaxies at z < 1. Aims: The populations of both quiescent and actively star-forming galaxies at 1 < z < 2 are still under-represented in our general census of galaxies throughout the history of the Universe. In the light of galaxy formation models, however, the evolution of galaxies at these redshifts is of pivotal importance and merits further investigation. In addition, photometry provides only limited clues about the nature and evolutionary status of these galaxies. We therefore designed a spectroscopic observing campaign of a sample of both massive, quiescent and star-forming galaxies at z > 1.4. Methods: To determine redshifts and physical properties, such as metallicity, dust content, dynamical masses, and star formation history, we performed ultra-deep spectroscopy with the red-sensitive optical spectrograph FORS2 at the Very Large Telescope. We first constructed a sample of objects, within the CDFS/GOODS area, detected at 4.5 μm, to be sensitive to stellar mass rather than star formation intensity. The spectroscopic targets were selected with a photometric redshift constraint (z > 1.4) and magnitude constraints (BAB < 26, IAB < 26.5), which should ensure that these are faint, distant, and fairly massive galaxies. Results: We present the sample selection, survey design, observations, data reduction, and spectroscopic redshifts. Up to 30 h of spectroscopy of 174 spectroscopic targets and 70 additional objects enabled us to determine 210 redshifts, of which 145 are at z > 1.4. The redshift distribution is clearly inhomogeneous with several pronounced redshift peaks. From the redshifts and photometry, we deduce that the BzK selection criteria are efficient (82%) and suffer low contamination

  16. The SAGES Legacy Unifying Globulars and Galaxies survey (SLUGGS): sample definition, methods, and initial results

    SciTech Connect

    Brodie, Jean P.; Romanowsky, Aaron J.; Jennings, Zachary G.; Pota, Vincenzo; Kader, Justin; Roediger, Joel C.; Villaume, Alexa; Arnold, Jacob A.; Woodley, Kristin A.; Strader, Jay; Forbes, Duncan A.; Pastorello, Nicola; Usher, Christopher; Blom, Christina; Kartha, Sreeja S.; Foster, Caroline; Spitler, Lee R.

    2014-11-20

    We introduce and provide the scientific motivation for a wide-field photometric and spectroscopic chemodynamical survey of nearby early-type galaxies (ETGs) and their globular cluster (GC) systems. The SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey is being carried out primarily with Subaru/Suprime-Cam and Keck/DEIMOS. The former provides deep gri imaging over a 900 arcmin{sup 2} field-of-view to characterize GC and host galaxy colors and spatial distributions, and to identify spectroscopic targets. The NIR Ca II triplet provides GC line-of-sight velocities and metallicities out to typically ∼8 R {sub e}, and to ∼15 R {sub e} in some cases. New techniques to extract integrated stellar kinematics and metallicities to large radii (∼2-3 R {sub e}) are used in concert with GC data to create two-dimensional (2D) velocity and metallicity maps for comparison with simulations of galaxy formation. The advantages of SLUGGS compared with other, complementary, 2D-chemodynamical surveys are its superior velocity resolution, radial extent, and multiple halo tracers. We describe the sample of 25 nearby ETGs, the selection criteria for galaxies and GCs, the observing strategies, the data reduction techniques, and modeling methods. The survey observations are nearly complete and more than 30 papers have so far been published using SLUGGS data. Here we summarize some initial results, including signatures of two-phase galaxy assembly, evidence for GC metallicity bimodality, and a novel framework for the formation of extended star clusters and ultracompact dwarfs. An integrated overview of current chemodynamical constraints on GC systems points to separate, in situ formation modes at high redshifts for metal-poor and metal-rich GCs.

  17. Supernova rates from the SUDARE VST-Omegacam search II. Rates in a galaxy sample

    NASA Astrophysics Data System (ADS)

    Botticella, M. T.; Cappellaro, E.; Greggio, L.; Pignata, G.; Della Valle, M.; Grado, A.; Limatola, L.; Baruffolo, A.; Benetti, S.; Bufano, F.; Capaccioli, M.; Cascone, E.; Covone, G.; De Cicco, D.; Falocco, S.; Haeussler, B.; Harutyunyan, V.; Jarvis, M.; Marchetti, L.; Napolitano, N. R.; Paolillo, M.; Pastorello, A.; Radovich, M.; Schipani, P.; Tomasella, L.; Turatto, M.; Vaccari, M.

    2017-02-01

    Aims: This is the second paper of a series in which we present measurements of the supernova (SN) rates from the SUDARE survey. The aim of this survey is to constrain the core collapse (CC) and Type Ia SN progenitors by analysing the dependence of their explosion rate on the properties of the parent stellar population averaging over a population of galaxies with different ages in a cosmic volume and in a galaxy sample. In this paper, we study the trend of the SN rates with the intrinsic colours, the star formation activity and the masses of the parent galaxies. To constrain the SN progenitors we compare the observed rates with model predictions assuming four progenitor models for SNe Ia with different distribution functions of the time intervals between the formation of the progenitor and the explosion, and a mass range of 8-40 M⊙ for CC SN progenitors. Methods: We considered a galaxy sample of approximately 130 000 galaxies and a SN sample of approximately 50 events. The wealth of photometric information for our galaxy sample allows us to apply the spectral energy distribution (SED) fitting technique to estimate the intrinsic rest frame colours, the stellar mass and star formation rate (SFR) for each galaxy in the sample. The galaxies have been separated into star-forming and quiescent galaxies, exploiting both the rest frame U-V vs. V-J colour-colour diagram and the best fit values of the specific star formation rate (sSFR) from the SED fitting. Results: We found that the SN Ia rate per unit mass is higher by a factor of six in the star-forming galaxies with respect to the passive galaxies, identified as such both on the U-V vs. V-J colour-colour diagram and for their sSFR. The SN Ia rate per unit mass is also higher in the less massive galaxies that are also younger. These results suggest a distribution of the delay times (DTD) less populated at long delay times than at short delays. The CC SN rate per unit mass is proportional to both the sSFR and the galaxy

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

    NASA Astrophysics Data System (ADS)

    Vavilkin, Tatjana

    2011-08-01

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

  19. BROAD Hβ EMISSION-LINE VARIABILITY IN A SAMPLE OF 102 LOCAL ACTIVE GALAXIES

    SciTech Connect

    Runco, Jordan N.; Cosens, Maren; Bennert, Vardha N.; Scott, Bryan; Komossa, S.; Malkan, Matthew A.; Treu, Tommaso; Lazarova, Mariana S.; Auger, Matthew W.; Park, Daeseong E-mail: mcosens@calpoly.edu E-mail: malkan@astro.ucla.edu E-mail: lazarovam2@unk.edu E-mail: daeseongpark@kasi.re.kr

    2016-04-10

    A sample of 102 local (0.02 ≤ z ≤ 0.1) Seyfert galaxies with black hole masses M{sub BH} > 10{sup 7}M{sub ⊙} was selected from the Sloan Digital Sky Survey (SDSS) and observed using the Keck 10 m telescope to study the scaling relations between M{sub BH} and host galaxy properties. We study profile changes of the broad Hβ emission line within the three to nine year time frame between the two sets of spectra. The variability of the broad Hβ emission line is of particular interest, not only because it is used to estimate M{sub BH}, but also because its strength and width are used to classify Seyfert galaxies into different types. At least some form of broad-line variability (in either width or flux) is observed in the majority (∼66%) of the objects, resulting in a Seyfert-type change for ∼38% of the objects, likely driven by variable accretion and/or obscuration. The broad Hβ line virtually disappears in 3/102 (∼3%) extreme cases. We discuss potential causes for these changing look active galactic nuclei. While similar dramatic transitions have previously been reported in the literature, either on a case-by-case basis or in larger samples focusing on quasars at higher redshifts, our study provides statistical information on the frequency of Hβ line variability in a sample of low-redshift Seyfert galaxies.

  20. Stellar Mass Functions of Galaxies At 4 < z < 7 from an IRAC-selected Sample in Cosmos/Ultravista: Limits on the Abundance of Very Massive Galaxies

    NASA Astrophysics Data System (ADS)

    Stefanon, Mauro; Marchesini, Danilo; Muzzin, Adam; Brammer, Gabriel; Dunlop, James S.; Franx, Marijin; Fynbo, Johan P. U.; Labbé, Ivo; Milvang-Jensen, Bo; van Dokkum, Pieter G.

    2015-04-01

    We build a Spitzer IRAC-complete catalog of objects complementing the Ks-band selected UltraVISTA catalog with objects detected in IRAC only. To identify massive (log ({{M}*}/{{M}⊙ })\\gt 11) galaxies at 4\\lt z\\lt 7, we consider the systematic effects on photometric redshift measurements from the introduction of an old and dusty template and of a bayesian prior on luminosity, as well as the systematic effects from different star formation histories (SFHs) and from nebular emission lines in estimated stellar population properties. Our results are most affected by the luminosity prior, while nebular lines and SFHs marginally increase the measurement dispersion; the samples include 52 to 382 galaxies, depending on the adopted configuration. Using these results we investigate, for the first time, the evolution of the massive end of the stellar mass functions (SMFs) at 4\\lt z\\lt 7. Given the rarity of massive galaxies at these redshifts, cosmic variance and Poisson noise dominate the total error budget. The SMFs obtained excluding the luminosity prior show no evolution from z˜ 6.5 to z˜ 3.5, indicating that massive galaxies could already be present at early epochs. The luminosity prior reduces the number of z\\gt 4 massive galaxies by 83%, implying a rapid growth of massive galaxies in the first 1.5 Gyr of cosmic history. The stellar-mass complete sample includes one candidate of a very massive (log ({{M}*}/{{M}⊙ })˜ 11.5), quiescent galaxy at z˜ 5.4 with MIPS 24 μ m detection, suggesting the presence of an obscured active galactic nucleus. Finally, we show that the observed number of 4\\lt z\\lt 7 massive galaxies matches the number of massive galaxies at 3\\lt z\\lt 6 predicted by current galaxy formation models.

  1. Far-infrared observations of an unbiased sample of gamma-ray burst host galaxies

    NASA Astrophysics Data System (ADS)

    Kohn, S. A.; Michałowski, M. J.; Bourne, N.; Baes, M.; Fritz, J.; Cooray, A.; De Looze, I.; De Zotti, G.; Dannerbauer, H.; Dunne, L.; Dye, S.; Eales, S.; Furlanetto, C.; Gonzalez-Nuevo, J.; Ibar, E.; Ivison, R. J.; Maddox, S. J.; Scott, D.; Smith, D. J. B.; Smith, M. W. L.; Symeonidis, M.; Valiante, E.

    2015-04-01

    Gamma-ray bursts (GRBs) are the most energetic phenomena in the Universe; believed to result from the collapse and subsequent explosion of massive stars. Even though it has profound consequences for our understanding of their nature and selection biases, little is known about the dust properties of the galaxies hosting GRBs. We present analysis of the far-infrared properties of an unbiased sample of 20 BeppoSAX and Swift GRB host galaxies (at an average redshift of z = 3.1) located in the Herschel Astrophysical Terahertz Large Area Survey, the Herschel Virgo Cluster Survey, the Herschel Fornax Cluster Survey, the Herschel Stripe 82 Survey and the Herschel Multi-tiered Extragalactic Survey, totalling 880 deg2, or ˜3 per cent of the sky in total. Our sample selection is serendipitous, based only on whether the X-ray position of a GRB lies within a large-scale Herschel survey - therefore our sample can be considered completely unbiased. Using deep data at wavelengths of 100-500 μm, we tentatively detected 1 out of 20 GRB hosts located in these fields. We constrain their dust masses and star formation rates (SFRs), and discuss these in the context of recent measurements of submillimetre galaxies and ultraluminous infrared galaxies. The average far-infrared flux of our sample gives an upper limit on SFR of <114 M⊙ yr-1. The detection rate of GRB hosts is consistent with that predicted assuming that GRBs trace the cosmic SFR density in an unbiased way, i.e. that the fraction of GRB hosts with SFR > 500 M⊙ yr-1 is consistent with the contribution of such luminous galaxies to the cosmic star formation density.

  2. Discordance of the unified scheme with observed properties of quasars and high-excitation galaxies in the 3CRR sample

    SciTech Connect

    Singal, Ashok K.

    2014-07-01

    We examine the consistency of the unified scheme of Fanaroff-Riley type II radio galaxies and quasars with their observed number and size distributions in the 3CRR sample. We separate the low-excitation galaxies from the high-excitation ones, as the former might not harbor a quasar within and thus may not be partaking in the unified scheme models. In the updated 3CRR sample, at low redshifts (z < 0.5), the relative number and luminosity distributions of high-excitation galaxies and quasars roughly match the expectations from the orientation-based unified scheme model. However, a foreshortening in the observed sizes of quasars, which is a must in the orientation-based model, is not seen with respect to radio galaxies even when the low-excitation galaxies are excluded. This dashes the hope that the unified scheme might still work if one includes only the high-excitation galaxies.

  3. The Brightest Galaxies at Cosmic Dawn: Securing the Largest Samples of z=9-11 galaxies for JWST by leveraging the HST archive with Spitzer/IRAC.

    NASA Astrophysics Data System (ADS)

    Bouwens, Rychard; Trenti, Michele; Calvi, Valentina; Bernard, Stephanie; Labbe, Ivo; Oesch, Pascal; Coe, Dan; Holwerda, Benne; Bradley, Larry; Mason, Charlotte; Schmidt, Kasper; Illingworth, Garth

    2015-10-01

    Hubble's WFC3 has been a game changer for studying early galaxy formation in the first 700 Myr after the Big Bang. Reliable samples of sources up to z~10, which can be discovered only from space, are now constraining the evolution of the galaxy luminosity function into the epoch of reionization. Despite these efforts, the size of the highest redshift galaxy samples (z >9 and especially z > 10) is still very small, particularly at high luminosities (L > L*). To deliver transformational results, much larger numbers of bright z > 9 galaxies are needed both to map out the bright end of the luminosity/mass function and for spectroscopic follow-up (with JWST and otherwise). One especially efficient way of expanding current samples is (1) to leverage the huge amounts of pure-parallel data available with HST to identify large numbers of candidate z ~ 9 - 11 galaxies and (2) to follow up each candidate with shallow Spitzer/IRAC observations to distinguish the bona- fide z ~ 9 - 11 galaxies from z ~ 2 old, dusty galaxies. For this program we are requesting shallow Spitzer/IRAC follow-up of 20 candidate z ~ 9 - 11 galaxies we have identified from 130 WFC3/IR pointings obtained from more than 4 separate HST programs with no existing IRAC coverage. Based on our previous CANDELS/GOODS searches, we expect to confirm 5 to 10 sources as L > L* galaxies at z >= 9. Our results will be used to constrain the bright end of the LF at z >= 9, to provide targets for Keck spectroscopy to constrain the ionization state of the z > 8 universe, and to furnish JWST with bright targets for spectroscopic follow-up studies.

  4. A large sample of Kohonen selected E+A (post-starburst) galaxies from the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Meusinger, H.; Brünecke, J.; Schalldach, P.; in der Au, A.

    2017-01-01

    Context. The galaxy population in the contemporary Universe is characterised by a clear bimodality, blue galaxies with significant ongoing star formation and red galaxies with only a little. The migration between the blue and the red cloud of galaxies is an issue of active research. Post starburst (PSB) galaxies are thought to be observed in the short-lived transition phase. Aims: We aim to create a large sample of local PSB galaxies from the Sloan Digital Sky Survey (SDSS) to study their characteristic properties, particularly morphological features indicative of gravitational distortions and indications for active galactic nuclei (AGNs). Another aim is to present a tool set for an efficient search in a large database of SDSS spectra based on Kohonen self-organising maps (SOMs). Methods: We computed a huge Kohonen SOM for 106 spectra from SDSS data release 7. The SOM is made fully available, in combination with an interactive user interface, for the astronomical community. We selected a large sample of PSB galaxies taking advantage of the clustering behaviour of the SOM. The morphologies of both PSB galaxies and randomly selected galaxies from a comparison sample in SDSS Stripe 82 (S82) were inspected on deep co-added SDSS images to search for indications of gravitational distortions. We used the Portsmouth galaxy property computations to study the evolutionary stage of the PSB galaxies and archival multi-wavelength data to search for hidden AGNs. Results: We compiled a catalogue of 2665 PSB galaxies with redshifts z < 0.4, among them 74 galaxies in S82 with EW(Hδ) > 3 Å and z < 0.25. In the colour-mass diagram, the PSB sample is clearly concentrated towards the region between the red and the blue cloud, in agreement with the idea that PSB galaxies represent the transitioning phase between actively and passively evolving galaxies. The relative frequency of distorted PSB galaxies is at least 57% for EW(Hδ) > 5 Å, significantly higher than in the comparison

  5. ROSAT Observations of a Complete Nearby Sample of Low Luminosity Radio Galaxies

    NASA Technical Reports Server (NTRS)

    Baum, Stefi

    2001-01-01

    We are studying the X-ray emission in a sample of nearby radio galaxies. The X-rays probe several important components: (1) the active galactic nuclei; (2) the interstellar medium of the host galaxy; and (3) the intergalactic or intracluster medium through which the jets propagate. The interaction of the radio plasma with the hot ambient gas will allow us to constrain the properties of the environments and the energetics of the radio source propagation. We have made excellent progress reducing the ROSAT new and archival data on our complete sample of nearby radio galaxies. The data reduction has taken longer than originally anticipated because we have identified bubbles of x-ray emission around many of the central galaxies and we have been exploring many different methodologies for assuring the results are robust before we publish and complete our interpretation. We have now begun the final phases of the work, with a draft paper under construction and a planned for submission date of early 2001. This work comprises 1/3 of the thesis work of a graduate student and will be the final phase in the completion of the thesis.

  6. A sample of galaxy pairs identified from the LAMOST spectral survey and the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Shen, Shi-Yin; Argudo-Fernández, Maria; Chen, Li; Chen, Xiao-Yan; Feng, Shuai; Hou, Jin-Liang; Hou, Yong-Hui; Jiang, Peng; Jing, Yi-Peng; Kong, Xu; Luo, A.-Li; Luo, Zhi-Jian; Shao, Zheng-Yi; Wang, Ting-Gui; Wang, Wen-Ting; Wang, Yue-Fei; Wu, Hong; Wu, Xue-Bing; Yang, Hai-Feng; Yang, Ming; Yuan, Fang-Ting; Yuan, Hai-Long; Zhang, Hao-Tong; Zhang, Jian-Nan; Zhang, Yong

    2016-03-01

    A small fraction (< 10%) of the SDSS main galaxy (MG) sample has not been targeted with spectroscopy due to the effect of fiber collisions. These galaxies have been compiled into the input catalog of the LAMOST ExtraGAlactic Surveys and named the complementary galaxy sample. In this paper, we introduce this project and status of the spectroscopies associated with the complementary galaxies in the first two years of the LAMOST spectral survey (till Sep. of 2014). Moreover, we present a sample of 1102 galaxy pairs identified from the LAMOST complementary galaxies and SDSS MGs, which are defined as two members that have a projected distance smaller than 100 h-170kpc and a recessional velocity difference smaller than 500 km s-1. Compared with galaxy pairs that are only selected from SDSS, the LAMOST-SDSS pairs have the advantages of not being biased toward large separations and therefore act as a useful supplement in statistical studies of galaxy interaction and galaxy merging.

  7. The Galaxy mass function up to z =4 in the GOODS-MUSIC sample: into the epoch of formation of massive galaxies

    NASA Astrophysics Data System (ADS)

    Fontana, A.; Salimbeni, S.; Grazian, A.; Giallongo, E.; Pentericci, L.; Nonino, M.; Fontanot, F.; Menci, N.; Monaco, P.; Cristiani, S.; Vanzella, E.; de Santis, C.; Gallozzi, S.

    2006-12-01

    Aims.The goal of this work is to measure the evolution of the Galaxy Stellar Mass Function and of the resulting Stellar Mass Density up to redshift ≃4, in order to study the assembly of massive galaxies in the high redshift Universe. Methods: .We have used the GOODS-MUSIC catalog, containing 3000 Ks-selected galaxies with multi-wavelength coverage extending from the U band to the Spitzer 8 μm band, of which 27% have spectroscopic redshifts and the remaining fraction have accurate photometric redshifts. On this sample we have applied a standard fitting procedure to measure stellar masses. We compute the Galaxy Stellar Mass Function and the resulting Stellar Mass Density up to redshift ≃4, taking into proper account the biases and incompleteness effects. Results: .Within the well known trend of global decline of the Stellar Mass Density with redshift, we show that the decline of the more massive galaxies may be described by an exponential timescale of ≃6 Gyr up to z≃ 1.5, and proceeds much faster thereafter, with an exponential timescale of ≃0.6 Gyr. We also show that there is some evidence for a differential evolution of the Galaxy Stellar Mass Function, with low mass galaxies evolving faster than more massive ones up to z≃ 1{-}1.5 and that the Galaxy Stellar Mass Function remains remarkably flat (i.e. with a slope close to the local one) up to z≃ 1{-}1.3. Conclusions: .The observed behaviour of the Galaxy Stellar Mass Function is consistent with a scenario where about 50% of present-day massive galaxies formed at a vigorous rate in the epoch between redshift 4 and 1.5, followed by a milder evolution until the present-day epoch.

  8. Multicolor surface photometry of a sample of low luminosity radio galaxies

    NASA Astrophysics Data System (ADS)

    Sahu, Sheetal Kumar; Pandey, S. K.; Chakradhari, N. K.; Baburao Pandge, Mahadev

    2015-08-01

    We present a detailed multiband photometric study of five galaxies, selected from a sample of low luminosity early-type galaxies from B2 sample, which have mpg = 15.7, mV = 16.5, redshifts up to 0.2, radio powers P408 = 1023 - 1026.5 W Hz-1 and between 1022 - 1025 W Hz-1 at 1.4 GHz. We have used observed BVR and Hα images from IGO 2m telescope (Pune, India) and 2m HCT, Indian Astronomical Observatory (IAO Hanle, India), and archival multiband data from SDSS (ugriz), 2MASS (JHKs ), WISE, Spitzer (mid-IR), XMM, CHANDRA (X-ray), UV (GALEX) and radio from VLA, IRAM for this study.We used standard technique of surface photometry by fitting ellipses to the isophotes for studying the distribution of light in the galaxies by studying their surface brightness profiles, ellipticity profiles, position angle profiles, variation of center of isophotes along semi-major axis, shapes of isophotes, radial color gradients, twists in isophotes and fine structure variations from smooth light profile. The obtained surface brightness profiles are fitted to the core-Sersic model for decomposing the galaxy light profiles and quantify the radial stellar distributions of the sample galaxies.The multiband color index profiles, e.g. u-g, g-r, r-i, i-z, B-R, B-V, J-Hs , J-Ks , H-Ks , R-Ks , 3.4-4.6 μm, 4.6-12 μm (mid-IR) and FUV-NUV(UV), are obtained and combined with various maps e.g . unsharp-masked images, residual maps, quotient maps, dust extinction maps, Hα emission maps, CO intensity maps, diffuse X-ray emission maps and extinction curves of the galaxies to study the morphology, properties and physical correlations of different phases (e.g cool gas, dust, ionized gas and hot gases) of Inter Stellar Medium and to examine various star formation related processes in the galaxies.

  9. Mass assembly of galaxies from the MASSIV survey and the MIRAGE simulation sample

    NASA Astrophysics Data System (ADS)

    Amram, Philippe

    2015-08-01

    The MIRAGE (Merging & isolated high-redshift AMR galaxies, Perret et al. 2014) sample has been built in order to understand the contribution of the merger processes to the mass assembly in the MASSIV (Mass Assembly Survey with SINFONI in VVDS, Contini et al. 2012) sample. It consists of a sample of idealized simulations based on the RAMSES code; the initial conditions were designed to reproduce the physical properties of the most gas-rich young galaxies. It is composed of simulations of mergers exploring the initial parameters of mass and orientation of the disks with a spatial resolution reaching 7 parsecs. We carry out a comparative study of the MASSIV kinematical data to a set of more than 4000 pseudo-observations at z=1.7 built from simulations of the MIRAGE sample to determine the ability to detect galaxy merger signatures under the observational conditions of the SINFONI instrument. The MIRAGE simulations show (i) an absence of star formation bursts in mergers of fragmented and turbulent disks, suggesting a saturation mechanism; (ii) that the gas rich clump merging mechanism is able to control the bulge mass growth, to erode the central profile of the dark matter halo and to drive massive gas outflows into the disk plane; (iii) irrespectively of the orbital configuration and of the mass ratio between the disks a new disk of gas is reconstructed quickly after the merger.

  10. Mass Assembly of galaxies from the MASSIV survey and the MIRAGE simulation sample.

    NASA Astrophysics Data System (ADS)

    Amram, Philippe

    2015-08-01

    The MIRAGE (Merging & isolated high-redshift AMR galaxies, Perret et al. 2014) sample has been built in order to understand the contribution of the merger processes to the mass assembly in the MASSIV (Mass Assembly Survey with SINFONI in VVDS, Contini et al. 2012) sample. It consists of a sample of idealized simulations based on the RAMSES code; the initial conditions were designed to reproduce the physical properties of the most gas-rich young galaxies. It is composed of simulations of mergers exploring the initial parameters of mass and orientation of the disks with a spatial resolution reaching 7 parsecs. We carry out a comparative study of the MASSIV kinematical data to a set of more than 4000 pseudo-observations at z=1.7 built from simulations of the MIRAGE sample to determine the ability to detect galaxy merger signatures under the observational conditions of the SINFONI instrument. The MIRAGE simulations show (i) an absence of star formation bursts in mergers of fragmented and turbulent disks, suggesting a saturation mechanism; (ii) that the gas rich clump merging mechanism is able to control the bulge mass growth, to erode the central profile of the dark matter halo and to drive massive gas outflows into the disk plane; (iii) irrespectively of the orbital configuration and of the mass ratio between the disks a new disk of gas is reconstructed quickly after the merger.

  11. DOUBLE-PEAKED NARROW EMISSION-LINE GALAXIES FROM THE SLOAN DIGITAL SKY SURVEY. I. SAMPLE AND BASIC PROPERTIES

    SciTech Connect

    Ge Junqiang; Hu Chen; Wang Jianmin; Zhang Shu; Bai Jinming

    2012-08-01

    Recently, much attention has been paid to double-peaked narrow emission-line (NEL) galaxies, some of which are suggested to be related to merging galaxies. We make a systematic search to build the largest sample of these sources from Data Release 7 of the Sloan Digital Sky Survey (SDSS). With reasonable criteria for fluxes, FWHMs of the emission lines, and separations of the peaks, we select 3030 double-peaked NEL galaxies. In light of the existence of broad Balmer lines and the locations of the two components of double-peaked NELs distinguished by the Kauffmann et al. criteria in the Baldwin-Phillips-Terlevich diagram, we find that there are 81 Type I active galactic nuclei (AGNs), 837 double Type II AGNs (2-Type II), 708 galaxies with double star-forming components (2-SF), 400 with mixed star-forming and Type II AGN components (Type II + SF), and 1004 unknown-type objects. As a by-product, a sample of galaxies (12,582) with asymmetric or top-flat profiles of emission lines is established. After visually inspecting the SDSS images of the two samples, we find 54 galaxies with dual cores. The present samples can be used to study the dynamics of merging galaxies, the triggering mechanism of black hole activity, the hierarchical growth of galaxies, and the dynamics of narrow line regions driven by outflows and a rotating disk.

  12. The Sloan Lens ACS Survey. I. A Large Spectroscopically Selected Sample of Massive Early-Type Lens Galaxies

    NASA Technical Reports Server (NTRS)

    Bolton, Adam S.; Burles, Scott; Koopmans, Leon V. E.; Treu, Tommaso; Moustakas, Leonidas A.

    2006-01-01

    The Sloan Lens ACS (SLACS) Survey is an efficient Hubble Space Telescope (HST) Snapshot imaging survey for new galaxy-scale strong gravitational lenses. The targeted lens candidates are selected spectroscopically from the Sloan Digital Sky Survey (SDSS) database of galaxy spectra for having multiple nebular emission lines at a redshift significantly higher than that of the SDSS target galaxy. The SLACS survey is optimized to detect bright early-type lens galaxies with faint lensed sources in order to increase the sample of known gravitational lenses suitable for detailed lensing, photometric, and dynamical modeling. In this paper, the first in a series on the current results of our HST Cycle 13 imaging survey, we present a catalog of 19 newly discovered gravitational lenses, along with nine other observed candidate systems that are either possible lenses, nonlenses, or nondetections. The survey efficiency is thus >=68%. We also present Gemini 8 m and Magellan 6.5 m integral-field spectroscopic data for nine of the SLACS targets, which further support the lensing interpretation. A new method for the effective subtraction of foreground galaxy images to reveal faint background features is presented. We show that the SLACS lens galaxies have colors and ellipticities typical of the spectroscopic parent sample from which they are drawn (SDSS luminous red galaxies and quiescent MAIN sample galaxies), but are somewhat brighter and more centrally concentrated. Several explanations for the latter bias are suggested. The SLACS survey provides the first statistically significant and homogeneously selected sample of bright early-type lens galaxies, furnishing a powerful probe of the structure of early-type galaxies within the half-light radius. The high confirmation rate of lenses in the SLACS survey suggests consideration of spectroscopic lens discovery as an explicit science goal of future spectroscopic galaxy surveys.

  13. The Sloan Lens ACS Survey. I. A Large Spectroscopically Selected Sample of Massive Early-Type Lens Galaxies

    NASA Technical Reports Server (NTRS)

    Bolton, Adam S.; Burles, Scott; Koopmans, Leon V. E.; Treu, Tommaso; Moustakas, Leonidas A.

    2006-01-01

    The Sloan Lens ACS (SLACS) Survey is an efficient Hubble Space Telescope (HST) Snapshot imaging survey for new galaxy-scale strong gravitational lenses. The targeted lens candidates are selected spectroscopically from the Sloan Digital Sky Survey (SDSS) database of galaxy spectra for having multiple nebular emission lines at a redshift significantly higher than that of the SDSS target galaxy. The SLACS survey is optimized to detect bright early-type lens galaxies with faint lensed sources in order to increase the sample of known gravitational lenses suitable for detailed lensing, photometric, and dynamical modeling. In this paper, the first in a series on the current results of our HST Cycle 13 imaging survey, we present a catalog of 19 newly discovered gravitational lenses, along with nine other observed candidate systems that are either possible lenses, nonlenses, or nondetections. The survey efficiency is thus >=68%. We also present Gemini 8 m and Magellan 6.5 m integral-field spectroscopic data for nine of the SLACS targets, which further support the lensing interpretation. A new method for the effective subtraction of foreground galaxy images to reveal faint background features is presented. We show that the SLACS lens galaxies have colors and ellipticities typical of the spectroscopic parent sample from which they are drawn (SDSS luminous red galaxies and quiescent MAIN sample galaxies), but are somewhat brighter and more centrally concentrated. Several explanations for the latter bias are suggested. The SLACS survey provides the first statistically significant and homogeneously selected sample of bright early-type lens galaxies, furnishing a powerful probe of the structure of early-type galaxies within the half-light radius. The high confirmation rate of lenses in the SLACS survey suggests consideration of spectroscopic lens discovery as an explicit science goal of future spectroscopic galaxy surveys.

  14. The WSRT wide-field H I survey. I. The background galaxy sample

    NASA Astrophysics Data System (ADS)

    Braun, R.; Thilker, D.; Walterbos, R. A. M.

    2003-08-01

    We have used the Westerbork array to carry out an unbiased wide-field survey for H I emission features, achieving an RMS sensitivity of about 18 mJy/Beam at a velocity resolution of 17 km s-1 over 1800 deg2 and between -1000 < VHel <+6500 km s-1. The primary data consists of auto-correlation spectra with an effective angular resolution of 49' FWHM, although cross-correlation data were also acquired. The survey region is centered approximately on the position of Messier 31 and is Nyquist-sampled over 60x 30o in RA x Dec. More than 100 distinct features are detected at high significance in each of the two velocity regimes (negative and positive LGSR velocities). In this paper we present the results for our H I detections of external galaxies at positive LGSR velocity. We detect 155 external galaxies in excess of 8sigma in integrated H I flux density. Plausible optical associations are found within a 30' search radius for all but one of our H I detections in DSS images, although several are not previously cataloged or do not have published red-shift determinations. Our detection without a DSS association is at low galactic latitude. Twenty-three of our objects are detected in H I for the first time. We classify almost half of our detections as ``confused'', since one or more companions is cataloged within a radius of 30' and a velocity interval of 400 km s-1. We identify a handful of instances of significant positional offsets exceeding 10 kpc of unconfused optical galaxies with the associated H I centroid, possibly indicative of severe tidal distortions or uncataloged gas-rich companions. A possible trend is found for an excess of detected H I flux in unconfused galaxies within our large survey beam relative to that detected previously in smaller telescope beams, both as function of increasing distance and increasing gas mass. This may be an indication for a diffuse gaseous component on 100 kpc scales in the environment of massive galaxies or a population of

  15. The Atacama Cosmology Telescope Sunyaev-Zel'dovich Equatorial Galaxy Cluster Sample

    NASA Astrophysics Data System (ADS)

    Menanteau, Felipe; Cosmology Telescope, Atacama

    2012-05-01

    We have reached the era where microwave surveys such as the Atacama Cosmology Telescope (ACT), the South Pole Telescope (SPT) and Planck are reporting the first samples of massive galaxy clusters through the Sunyaev-Zel'dovich (SZ) effect. Here I will introduce a new mass-selected and redshift-independent sample of optically-confirmed galaxy clusters detected by ACT over approximately 300 square-degrees along the celestial equator overlapping the deep optical u,g,r,i and z imaging from SDSS Stripe 82. This work was supported by the U.S. National Science Foundation through awards AST- 0408698 for the ACT project and PHY-0355328, AST-0707731, and PIRE-0507768 (award number OISE-0530095).

  16. Redshift Survey of Galaxies around a Selected Sample of Compact Groups

    NASA Astrophysics Data System (ADS)

    de Carvalho, Reinaldo R.; Ribeiro, André L. B.; Capelato, Hugo V.; Zepf, Stephen E.

    We report the results of a spectroscopic survey of faint galaxies in the regions surrounding Hickson compact groups. Our sample is composed of 17 groups within 9000 km s-1. The spectra were taken at the prime focus of the Tololo 4 m telescope, using the ARGUS fiber-fed spectrograph. From these observations, redshifts were determined for the faint galaxies previously identified by de Carvalho, Ribeiro, & Zepf in the surroundings of the groups. Statistical methods were applied to the resultant catalog in order to determine the kinematical structure of each group. This analysis confirms the idea that the Hickson sample of compact groups contains a wide variety of projection and dynamical configurations. Our results demonstrate the necessity of new spectroscopic surveys around compact groups in order to assess their complete velocity distribution.

  17. Gas and Stars in an H I-Selected Galaxy Sample

    NASA Astrophysics Data System (ADS)

    Rosenberg, Jessica L.; Schneider, Stephen E.; Posson-Brown, Jennifer

    2005-03-01

    We present the results of a J-band study of the H I-selected Arecibo Dual-Beam Survey and Arecibo Slice Survey galaxy samples using Two Micron All Sky Survey data. We find that these galaxies span a wide range of stellar and gas properties. However, despite the diversity within the samples, we find a very tight correlation between luminosity and size in the J band, similar to that found in a previous paper by Rosenberg & Schneider between the H I mass and size. We also find that the correlation between the baryonic mass and the J-band diameter is even tighter than that between the baryonic mass and the rotational velocity.

  18. Observations of Paschen alpha in a Complete Sample of Radio Galaxies

    NASA Astrophysics Data System (ADS)

    Hill, Gary J.; Goodrich, Robert W.; Depoy, D. L.

    1996-05-01

    We present infrared spectrophotometry of the Paα (n = 4-3) emission line of hydrogen, together with optical spectrophotometry of Hα and Hβ, of a flux-limited sample of 11 radio sources. The sample consists of all FR II 3CR radio sources with 0.1 <= z <= 0.2 and 5^h^ < R.A. < 16^h^ which contains eight narrow-line radio galaxies (3CR 135, 184.1, 219, 223, 236, 319, 321, and 327), two broad-line radio galaxies (3CR 234 and 3CR 303), and one quasar (3CR 273). The observations were aimed at the detection of obscured broad lines, hidden from our view by dust absorption, as a means of testing theories of the unification of radio galaxies and quasars. All the objects except 3CR 236 and 3CR 273 show significant reddening of the narrow and broad lines, typically of order A_V_ ~ 1.5 for narrow lines and ~3 for broad lines. We detect highly obscured broad-line regions in 3CR 184.1, 219, and 223, which appear to be narrow-line objects in the optical, so these should be reclassified as broad-line radio galaxies. In all cases except 3CR 273 and 3CR 303, the broad lines are reddened more than the narrow lines, locating much of the dust responsible for absorbing the broad-line emission between the broad- and narrow-line regions. The dereddened line luminosities range up to those of low-luminosity quasars. The results are broadly consistent with models which seek to unify radio galaxies and quasars through orientation, where an axisymmetric equatorial obscuring region hides the quasar nucleus from view unless the radio axis is pointing close to our line of sight. These data provide the first opportunity to model the distribution of broad-line region extinctions in a complete sample, rather than model just the fraction of quasars and radio galaxies. We develop a simple unification model that matches the observed distribution of extinctions, explains our observations, and makes predictions about the fraction of obscured quasars that will be present in samples of higher radio

  19. Sample of Wolf-Rayet galaxies from the SLOAN digital sky survey

    NASA Astrophysics Data System (ADS)

    Agienko, K. B.; Guseva, N. G.; Izotov, Yu. I.

    2013-05-01

    We have analyzed the spectra of blue compact dwarf galaxies from the SLOAN Digital Sky Survey (SDSS) Data Release 7 and created a sample of 271 galaxies with Wolf-Rayet (WR) spectral features produced by high-velocity stellar winds. A blue WR feature (bump) is a blend of the N V λλ 460.5 and 462.0 nm, N III λλ 463.4 and 464.0 nm, C III λλ 465.0 nm, C IV λ 465.8 nm, and He II λ 468.6 nm emission lines. A red WR feature (bump) is the broad C IV λ 580.8 nm emission. The blue WR bump is mainly due to emissions of nitrogen WR (WN) stars, while the red bump is fully produced by emissions of carbon WR (WC) stars. All the sample spectra show the blue WR bumps, whereas the red WR bumps are only identified in 50% of sample spectra. We have derived the numbers of early-type WC stars (WCE) and late-type WN stars (WNL) in the galaxies using the luminosities of single WC and WN stars in the red and blue bumps, respectively. The number of O stars is estimated using the Hβ luminosity. The ratio of the overall number of WR stars of different types to the number of all massive stars N(WR)/N(O + WR) decreases with decreasing metallicity, corresponding to the evolution population synthesis models.

  20. Integral field spectroscopy of a sample of nearby galaxies. II. Properties of the H ii regions

    NASA Astrophysics Data System (ADS)

    Sánchez, S. F.; Rosales-Ortega, F. F.; Marino, R. A.; Iglesias-Páramo, J.; Vílchez, J. M.; Kennicutt, R. C.; Díaz, A. I.; Mast, D.; Monreal-Ibero, A.; García-Benito, R.; Bland-Hawthorn, J.; Pérez, E.; González Delgado, R.; Husemann, B.; López-Sánchez, Á. R.; Cid Fernandes, R.; Kehrig, C.; Walcher, C. J.; Gil de Paz, A.; Ellis, S.

    2012-10-01

    We analyse the spectroscopic properties of thousands of H ii regions identified in 38 face-on spiral galaxies. All galaxies were observed out to 2.4 effective radii using integral field spectroscopy (IFS) over the wavelength range ~3700 to ~6900 Å. The near uniform sample has been assembled from the PPAK IFS Nearby Galaxy (PINGS) survey and a sample described in Paper I. We develop a new automatic procedure to detect H ii regions, based on the contrast of the Hα intensity maps extracted from the datacubes. Once detected, the algorithm provides us with the integrated spectra of each individual segmented region. In total, we derive good quality spectroscopic information for ~2600 independent H ii regions/complexes. This is by far the largest H ii region survey of its kind. Our selection criteria and the use of 3D spectroscopy guarantee that we cover the regions in an unbiased way. A well-tested automatic decoupling procedure has been applied to remove the underlying stellar population, deriving the main properties (intensity, dispersion and velocity) of the strongest emission lines in the considered wavelength range (covering from [O ii] λ3727 to [S ii] λ6731). A final catalogue of the spectroscopic properties of H ii regions has been created for each galaxy, which includes information on morphology, spiral structure, gaskinematics, and surface brightness of the underlying stellar population. In the current study, we focus on the understanding of the average properties of the H ii regions and their radial distributions. We find a significant change in the ionisation characteristics of H ii regions within r < 0.25 re due to contamination from sources with different ionising characteristics, as we discuss. We find that the gas-phase oxygen abundance and the Hα equivalent width present a negative and positive gradient, respectively. The distribution of slopes is statistically compatible with a random Gaussian distribution around the mean value, if the radial

  1. VLBI observations of a complete sample of radio galaxies. 4: The radio galaxies NGC 2484, 3C 109, and 3C 382

    NASA Technical Reports Server (NTRS)

    Giovannini, G.; Feretti, L.; Venturi, T.; Lara, L.; Marcaide, J.; Rioja, M.; Spangler, S. R.; Wehrle, A. E.

    1994-01-01

    We present here new Very Long Base Interferometry (VLBI) observations of one Fanaroff and Riley (F-R) I radio galaxy (NGC 2484) and two broad-line F-R II radio galaxies (3C 109 and 3C 382). For 3C 109 new Very Large Array (VLA) maps are also shown. These sources belong to a complete sample of radio galaxies under study for a better knowledge of their structures at parsec resolution. The parsec structure of these three objects is very similar: asymmetric emission, which we interpret as the core plus a one-side jet. The parsec-scale jet is always on the same side of the main kiloparsec-scale jet. The limit on the jet to counterjet brightness ratio, the ratio of the core radio power to the total radio power and the synchrotron-self Compton model allow us to derive some constraints on the jet velocity and orientation with respect to the line of sight. From these data and from those published on two other sources of our sample, we suggest that parsec-scale jets are relativistic in both F-R I and F-R II radio galaxies and that parsec scale properties in F-R I and F-R II radio galaxies are very similar despite the large difference between these two classes of radio galaxies on the kiloparsec scale.

  2. VLBI observations of a complete sample of radio galaxies. 4: The radio galaxies NGC 2484, 3C 109, and 3C 382

    NASA Technical Reports Server (NTRS)

    Giovannini, G.; Feretti, L.; Venturi, T.; Lara, L.; Marcaide, J.; Rioja, M.; Spangler, S. R.; Wehrle, A. E.

    1994-01-01

    We present here new Very Long Base Interferometry (VLBI) observations of one Fanaroff and Riley (F-R) I radio galaxy (NGC 2484) and two broad-line F-R II radio galaxies (3C 109 and 3C 382). For 3C 109 new Very Large Array (VLA) maps are also shown. These sources belong to a complete sample of radio galaxies under study for a better knowledge of their structures at parsec resolution. The parsec structure of these three objects is very similar: asymmetric emission, which we interpret as the core plus a one-side jet. The parsec-scale jet is always on the same side of the main kiloparsec-scale jet. The limit on the jet to counterjet brightness ratio, the ratio of the core radio power to the total radio power and the synchrotron-self Compton model allow us to derive some constraints on the jet velocity and orientation with respect to the line of sight. From these data and from those published on two other sources of our sample, we suggest that parsec-scale jets are relativistic in both F-R I and F-R II radio galaxies and that parsec scale properties in F-R I and F-R II radio galaxies are very similar despite the large difference between these two classes of radio galaxies on the kiloparsec scale.

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

    NASA Astrophysics Data System (ADS)

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

    2017-10-01

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

  4. A COMPLETE SAMPLE OF ULTRALUMINOUS X-RAY SOURCE HOST GALAXIES

    SciTech Connect

    Swartz, Douglas A.; Soria, Roberto; Tennant, Allyn F.; Yukita, Mihoko

    2011-11-01

    One hundred seven ultraluminous X-ray sources (ULXs) with 0.3-10.0 keV luminosities in excess of 10{sup 39} erg s{sup -1} are identified in a complete sample of 127 nearby galaxies. The sample includes all galaxies within 14.5 Mpc above the completeness limits of both the Uppsala Galaxy Catalogue and the Infrared Astronomical Satellite survey. The galaxy sample spans all Hubble types, a four-decade range in mass, 7.5 < log (M/M{sub sun}) < 11.4, and in star formation rate, 0.0002 < SFR(M{sub sun} yr{sup -1}) {<=} 3.6. ULXs are detected in this sample at rates of one per 3.2 Multiplication-Sign 10{sup 10} M{sub sun}, one per {approx}0.5 M{sub sun} yr{sup -1} star formation rate, and one per 57 Mpc{sup 3} corresponding to a luminosity density of {approx}2 Multiplication-Sign 10{sup 37} erg s{sup -1} Mpc{sup -3}. At these rates we estimate as many as 19 additional ULXs remain undetected in fainter dwarf galaxies within the survey volume. An estimated 14 objects, or 13%, of the 107 ULX candidates are expected to be background sources. The differential ULX luminosity function shows a power-law slope {alpha} {approx} -0.8 to -2.0 with an exponential cutoff at {approx}20 Multiplication-Sign 10{sup 39} erg s{sup -1} with precise values depending on the model and on whether the ULX luminosities are estimated from their observed numbers of counts or, for a subset of candidates, from their spectral shapes. Extrapolating the observed luminosity function predicts at most one very luminous ULX, L{sub X} {approx} 10{sup 41} erg s{sup -1}, within a distance as small as 100 Mpc. The luminosity distribution of ULXs within the local universe cannot account for the recent claims of luminosities in excess of 2 Multiplication-Sign 10{sup 41} erg s{sup -1}, requiring a new population class to explain these extreme objects.

  5. A redshift survey of IRAS galaxies. VII - The infrared and redshift data for the 1.936 Jansky sample

    NASA Technical Reports Server (NTRS)

    Strauss, Michael A.; Huchra, John P.; Davis, Marc; Yahil, Amos; Fisher, Karl B.; Tonry, John

    1992-01-01

    We present the data for a redshift survey of galaxies selected from the database of the Infrared Astronomical Satellite (IRAS). The sample is flux limited to 1.936 Jy at 60 microns and covers 11.01 sr of the sky. It consists of 5014 objects, of which 2658 are galaxies. The remaining 2356 sources are listed in a separate table with identifications. Redshift data are also given for 212 IRAS galaxies which are not part of the complete sample, but were measured in conjunction with this project.

  6. The Properties of X-ray Cold Fronts in a Statistical Sample of Simulated Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Hallman, Eric J.; Skillman, Samuel W.; Jeltema, Tesla E.; Smith, Britton D.; O'Shea, Brian W.; Burns, Jack O.; Norman, Michael L.

    2010-12-01

    We examine the incidence of cold fronts in a large sample of galaxy clusters extracted from a (512 h -1 Mpc) hydrodynamic/N-body cosmological simulation with adiabatic gas physics computed with the Enzo adaptive mesh refinement code. This simulation contains a sample of roughly 4000 galaxy clusters with M >=1014 M sun at z = 0. For each simulated galaxy cluster, we have created mock 0.3-8.0 keV X-ray observations and spectroscopic-like temperature maps. We have searched these maps with a new automated algorithm to identify the presence of cold fronts in projection. Using a threshold of a minimum of 10 cold front pixels in our images, corresponding to a total comoving length L cf>156 h -1 kpc, we find that roughly 10%-12% of all projections in a mass-limited sample would be classified as cold front clusters. Interestingly, the fraction of clusters with extended cold front features in our synthetic maps of a mass-limited sample trends only weakly with redshift out to z = 1.0. However, when using different selection functions, including a simulated flux limit, the trending with redshift changes significantly. The likelihood of finding cold fronts in the simulated clusters in our sample is a strong function of cluster mass. In clusters with M>7.5 × 1014 M sun the cold front fraction is 40%-50%. We also show that the presence of cold fronts is strongly correlated with disturbed morphology as measured by quantitative structure measures. Finally, we find that the incidence of cold fronts in the simulated cluster images is strongly dependent on baryonic physics.

  7. THE PROPERTIES OF X-RAY COLD FRONTS IN A STATISTICAL SAMPLE OF SIMULATED GALAXY CLUSTERS

    SciTech Connect

    Hallman, Eric J.; Skillman, Samuel W.; Smith, Britton D.; Burns, Jack O.; Jeltema, Tesla E.; Norman, Michael L.

    2010-12-10

    We examine the incidence of cold fronts in a large sample of galaxy clusters extracted from a (512 h {sup -1} Mpc) hydrodynamic/N-body cosmological simulation with adiabatic gas physics computed with the Enzo adaptive mesh refinement code. This simulation contains a sample of roughly 4000 galaxy clusters with M {>=}10{sup 14} M{sub sun} at z = 0. For each simulated galaxy cluster, we have created mock 0.3-8.0 keV X-ray observations and spectroscopic-like temperature maps. We have searched these maps with a new automated algorithm to identify the presence of cold fronts in projection. Using a threshold of a minimum of 10 cold front pixels in our images, corresponding to a total comoving length L{sub cf}>156 h {sup -1} kpc, we find that roughly 10%-12% of all projections in a mass-limited sample would be classified as cold front clusters. Interestingly, the fraction of clusters with extended cold front features in our synthetic maps of a mass-limited sample trends only weakly with redshift out to z = 1.0. However, when using different selection functions, including a simulated flux limit, the trending with redshift changes significantly. The likelihood of finding cold fronts in the simulated clusters in our sample is a strong function of cluster mass. In clusters with M>7.5 x 10{sup 14} M{sub sun} the cold front fraction is 40%-50%. We also show that the presence of cold fronts is strongly correlated with disturbed morphology as measured by quantitative structure measures. Finally, we find that the incidence of cold fronts in the simulated cluster images is strongly dependent on baryonic physics.

  8. Ca II AND Na I QUASAR ABSORPTION-LINE SYSTEMS IN AN EMISSION-SELECTED SAMPLE OF SDSS DR7 GALAXY/QUASAR PROJECTIONS. I. SAMPLE SELECTION

    SciTech Connect

    Cherinka, B.; Schulte-Ladbeck, R. E.

    2011-10-15

    The aim of this project is to identify low-redshift host galaxies of quasar absorption-line systems by selecting galaxies that are seen in projection onto quasar sightlines. To this end, we use the Seventh Data Release of the Sloan Digital Sky Survey to construct a parent sample of 97,489 galaxy/quasar projections at impact parameters of up to 100 kpc to the foreground galaxy. We then search the quasar spectra for absorption-line systems of Ca II and Na I within {+-}500 km s{sup -1} of the galaxy's velocity. This yields 92 Ca II and 16 Na I absorption systems. We find that most of the Ca II and Na I systems are sightlines through the Galactic disk, through high-velocity cloud complexes in our halo, or Virgo Cluster sightlines. Placing constraints on the absorption line rest equivalent width significance ({>=}3.0{sigma}), the local standard of rest velocity along the sightline ({>=}345 km s{sup -1}), and the ratio of the impact parameter to the galaxy optical radius ({<=}5.0), we identify four absorption-line systems that are associated with low-redshift galaxies at high confidence, consisting of two Ca II systems (one of which also shows Na I) and two Na I systems. These four systems arise in blue, {approx}L*{sub r} galaxies. Tables of the 108 absorption systems are provided to facilitate future follow-up.

  9. The Wasilewski sample of emission-line galaxies - Follow-up CCD imaging and spectroscopic and IRAS observations

    NASA Technical Reports Server (NTRS)

    Bothun, Gregory D.; Schmitz, Mark; Halpern, Jules P.; Lonsdale, Carol J.; Impey, Chris

    1989-01-01

    The results of an extensive imaging and spectroscopic follow-up of the objective prism-selected emission line galaxy (ELG) sample of Wasilewski (1982) are presented. Fluxes at 12, 25, 60, and 100 microns were also obtained from the coadded IRAS survey data. ELGs found by objective prism surveys are found to be generally small and underluminous galaxies which usually have higher than average optical surface brightness. The Seyfert detection rate in objective prism surveys is roughly 10 percent and the ratio of the space densities of Seyfert 2 to Seyfert 1 galaxies is significantly larger than unity. Most of the galaxies selected by objective prism surveys are star-forming, late-type spirals which often show disturbed morphology. About 25 percent of the galaxies detected by the surveys are faint, high-excitation metal-poor compact H II regions.

  10. A Further Examination of Manifold Theory

    NASA Astrophysics Data System (ADS)

    Treuthardt, Patrick; Grouchy, Rebecca

    2015-08-01

    Manifold theory, an alternative to density wave theory, proposes that the spiral structure found in disk galaxies is the result of chaotic orbits guided by invariant manifolds. One prediction by this theory is that galaxies with stronger bars have more open spiral arms (i.e. larger pitch angles, P) compared to galaxies with weaker bars. A study by Martínez-García examined a limited sample of 27 galaxies from the Ohio State University Bright Galaxy Survey (OSUBGS) and found a trend between the overall perturbation strength in a galaxy, Qt(r), and P. While Qt(r) is a good measure of bar strength, it is affected by spiral arm torques. Our analysis advances that of Martínez-García by studying approximately 100 galaxies from the OSUBGS that have separate bar and spiral perturbation strength calculations and comparing these values to robust measurements of P via an algorithm developed by Davis et al.

  11. Near-infrared surface photometry of a sample of barred galaxies

    NASA Astrophysics Data System (ADS)

    Gadotti, D. A.; Athanassoula, E.; Carrasco, L.; Bosma, A.; de Souza, R. E.; Recillas, E.

    2007-11-01

    We have obtained deep J and Ks images of a sample of nine barred galaxies in order to collect a reliable and homogeneous set of images to which N-body simulations of barred galaxies will be compared. The observations were performed using the new near-infrared camera available at the 2.1-m telescope of the Observatorio Astrofísico Guillermo Haro (OAGH) in Cananea, Sonora, Mexico. We present the results of surface photometry techniques applied to the observed images, as well as to the deprojected images. These results include radial profiles of surface brightness (elliptically averaged), colour, position angle, ellipticity and the b4 Fourier component. In addition, we present isophotal maps, colour maps, surface brightness profiles along the bar major and minor axes, characteristic radial scalelengths and bar length estimates. We discuss how projection effects can influence these measurements and the uncertainties introduced by deprojecting galaxy images. We show that analytical expressions can be used to obtain reliable estimates of deprojected bar lengths, ellipticities and position angles directly from the observed images. These expressions are based on the assumption that the outer parts of the bar are vertically thin, as shown by theoretical work. The usefulness of our data in addressing issues on bar formation and evolution is also discussed. In particular, we present results showing a steep drop in the ellipticity profile, as expected for bar formation processes in which the dark matter halo plays a fundamental role. Furthermore, we show that the location of this drop is a good indicator of the end of the bar in strongly barred galaxies, as predicted by numerical models.

  12. A spectroscopic sample of massive, quiescent z ∼ 2 galaxies: implications for the evolution of the mass-size relation

    SciTech Connect

    Krogager, J.-K.; Zirm, A. W.; Toft, S.; Man, A.; Brammer, G.

    2014-12-10

    We present deep, near-infrared Hubble Space Telescope/Wide Field Camera 3 grism spectroscopy and imaging for a sample of 14 galaxies at z ≈ 2 selected from a mass-complete photometric catalog in the COSMOS field. By combining the grism observations with photometry in 30 bands, we derive accurate constraints on their redshifts, stellar masses, ages, dust extinction, and formation redshifts. We show that the slope and scatter of the z ∼ 2 mass-size relation of quiescent galaxies is consistent with the local relation, and confirm previous findings that the sizes for a given mass are smaller by a factor of two to three. Finally, we show that the observed evolution of the mass-size relation of quiescent galaxies between z = 2 and 0 can be explained by the quenching of increasingly larger star forming galaxies at a rate dictated by the increase in the number density of quiescent galaxies with decreasing redshift. However, we find that the scatter in the mass-size relation should increase in the quenching-driven scenario in contrast to what is seen in the data. This suggests that merging is not needed to explain the evolution of the median mass-size relation of massive galaxies, but may still be required to tighten its scatter, and explain the size growth of individual z = 2 galaxies quiescent galaxies.

  13. Brightest cluster galaxies in the extended GMRT radio halo cluster sample. Radio properties and cluster dynamics

    NASA Astrophysics Data System (ADS)

    Kale, R.; Venturi, T.; Cassano, R.; Giacintucci, S.; Bardelli, S.; Dallacasa, D.; Zucca, E.

    2015-09-01

    Aims: First-ranked galaxies in clusters, usually referred to as brightest cluster galaxies (BCGs), show exceptional properties over the whole electromagnetic spectrum. They are the most massive elliptical galaxies and show the highest probability to be radio loud. Moreover, their special location at the centres of galaxy clusters raises the question of the role of the environment in shaping their radio properties. In the attempt to separate the effect of the galaxy mass and of the environment on their statistical radio properties, we investigate the possible dependence of the occurrence of radio loudness and of the fractional radio luminosity function on the dynamical state of the hosting cluster. Methods: We studied the radio properties of the BCGs in the Extended GMRT Radio Halo Survey (EGRHS), which consists of 65 clusters in the redshift range 0.2-0.4, with X-ray luminosity LX ≥ 5 × 1044 erg s-1, and quantitative information on their dynamical state from high-quality Chandra imaging. We obtained a statistical sample of 59 BCGs, which we divided into two classes, depending on whether the dynamical state of the host cluster was merging (M) or relaxed (R). Results: Of the 59 BCGs, 28 are radio loud and 31 are radio quiet. The radio-loud sources are favourably located in relaxed clusters (71%), while the reverse is true for the radio-quiet BCGs, which are mostly located in merging systems (81%). The fractional radio luminosity function for the BCGs in merging and relaxed clusters is different, and it is considerably higher for BCGs in relaxed clusters, where the total fraction of radio loudness reaches almost 90%, to be compared to the ~30% in merging clusters. For relaxed clusters, we found a positive correlation between the radio power of the BCGs and the strength of the cool core, consistent with previous studies on local samples. Conclusions: Our study suggests that the radio loudness of the BCGs strongly depends on the cluster dynamics; their fraction is

  14. VizieR Online Data Catalog: DYNAMO. Hα luminous galaxies sample (Green+, 2014)

    NASA Astrophysics Data System (ADS)

    Green, A. W.; Glazebrook, K.; McGregor, P. J.; Damjanov, I.; Wisnioski, E.; Abraham, R. G.; Colless, M.; Sharp, R. G.; Crain, R. A.; Poole, G. B.; McCarthy, P. J.

    2014-11-01

    We have selected a representative sample of 67 galaxies classified as star forming in the Max-Planck-Institut fur Astrophysik and Johns Hopkins University (MPA-JHU) value-added catalogue (http://www.mpa-garching.mpg.de/SDSS/DR4/) of the Sloan Digital Sky Survey (SDSS, York et al., 2000AJ....120.1579Y). Integral-field spectroscopic data were obtained using two different telescopes; the 3.9m Anglo-Australian Telescope and the ANU 2.3m Telescope, both situated at Siding Spring Observatory, Australia. (4 data files).

  15. SPECTROSCOPIC PROPERTIES OF STAR-FORMING HOST GALAXIES AND TYPE Ia SUPERNOVA HUBBLE RESIDUALS IN A NEARLY UNBIASED SAMPLE

    SciTech Connect

    D'Andrea, Chris B.; Gupta, Ravi R.; Sako, Masao; Morris, Matt; Nichol, Robert C.; Campbell, Heather; Lampeitl, Hubert; Brown, Peter J.; Olmstead, Matthew D.; Frieman, Joshua A.; Kessler, Richard; Garnavich, Peter; Jha, Saurabh W.; Marriner, John; Schneider, Donald P.; Smith, Mathew

    2011-12-20

    We examine the correlation between supernova (SN) host-galaxy properties and their residuals in the Hubble diagram. We use SNe 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 (SN Ia) 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{sub 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 (SFRs) from host galaxies with active star formation. From a final sample of {approx}40 emission-line galaxies, we find that light-curve-corrected SNe Ia are {approx}0.1 mag brighter in high-metallicity hosts than in low-metallicity hosts. We also find a significant (>3{sigma}) correlation between the Hubble Residuals of SNe Ia and the specific SFR of the host galaxy. We comment on the importance of SN/host-galaxy correlations as a source of systematic bias in future deep SN surveys.

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

    SciTech Connect

    D'Andrea, Chris B.; 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.

  17. The Fraction of Stars Formed In A Diverse Sample of 8 Galaxies

    NASA Astrophysics Data System (ADS)

    Chandar, Rupali

    2017-01-01

    We have estimated the fraction of stars born in compact star clusters, Gamma, in a diverse sample of 8 galaxies, including two irregulars, two dwarf starbursts, two spirals, and two mergers. We find an average value for our sample of Gamma ~30 +/- 12 %. We also calculate the fraction of stars found in clusters that have survived to older ages, and find values of 4.6 +/- 2.5% for 10-100 Myr clusters, and 2.4+/-1.1 % for 100-400 Myr clusters. Intriguingly, Gamma does not appear to vary with the star formation rate (SFR), the SFR density or the gas density in our sample. These new results are at odds with the well-established picture where a higher fraction of stars form in clusters when the star formation and gas densities are high. We explore reasons for the differences between our results and previous work, and describe how the LEGUS plus Halpha-LEGUS surveys will be used to help settle the issue of whether or not Gamma varies with galaxy property.

  18. Occurrence of radio halos in galaxy clusters. Insight from a mass-selected sample

    NASA Astrophysics Data System (ADS)

    Cuciti, V.; Cassano, R.; Brunetti, G.; Dallacasa, D.; Kale, R.; Ettori, S.; Venturi, T.

    2015-08-01

    Context. Giant radio halos (RH) are diffuse Mpc-scale synchrotron sources detected in some massive and merging galaxy clusters. An unbiased study of the statistical properties of RHs is crucial to constraining their origin and evolution. Aims: We investigate the occurrence of RHs and its dependence on the cluster mass in a Sunyaev-Zel'dovich (SZ)-selected sample of galaxy clusters, which is nearly a mass-selected sample. Moreover, we analyse the connection between RHs and merging clusters. Methods: We selected from the Planck SZ catalogue clusters with M ≥ 6 × 1014M⊙ at z = 0.08-0.33 and we searched for the presence of RHs using the NVSS for z < 0.2 and the GMRT RH survey (GRHS) and its extension (EGRHS) for 0.2 < z < 0.33. We used archival Chandra X-ray data to derive information on the dynamical status of the clusters. Results: We confirm that RH clusters are merging systems while the majority of clusters without RH are relaxed, thus supporting the idea that mergers play a fundamental role in the generation of RHs. We find evidence for an increase in the fraction of clusters with RHs with the cluster mass and this is in line with expectations derived on the basis of the turbulence re-acceleration scenario. Finally, we discuss the effect of the incompleteness of our sample on this result.

  19. The CoNFIG FRI sample: evolution of FRI galaxies and their role in AGN feedback.

    NASA Astrophysics Data System (ADS)

    Gendre, Melanie; Ricci, Roberto; Wall, Jasper; Feain, Ilana; Best, Philip; Dunlop, James; Grant, Julie; Taylor, Russ; Stil, Jeroen

    2008-10-01

    The proposal is to examine two major AGN aspects: (1) detailed testing and analysis of the FRI-galaxy space density evolution, (2) to study the polarization properties of AGN cores as a function of flux and redshift and (3) a precise history of cosmic downsizing ('differential evolution') in radio AGN to examine the importance of FRI versus FRII sources in the AGN feedback process now appearing to govern galaxy formation. The investigation is based on the CoNFIG FRI sub-samples (obtained from the 1.4-GHz NVSS in regions of FIRST) and the CENSORS sample (obtained from the NVSS and the deep EIS optical survey in a small region of southern sky). From these we have a total of 206 extragalactic sources for which we desire unambiguous morphologies and FRI/FRII classification in particular. Of the 206 sources, we request ATCA 6km array observations at 3 cm for 40 sources which, from our previous observations and analysis, remain ambiguous in classification. This sample can at last define the detailed cosmic evolution of FRI radio sources together with the 'transition region' to FRII sources.

  20. H I detection survey of a complete magnitude-limited sample of dwarf irregular galaxies in the Virgo Cluster area

    NASA Technical Reports Server (NTRS)

    Hoffman, G. Lyle; Glosson, John; Helou, George; Salpeter, E. E.; Sandage, A.

    1987-01-01

    New single-beam Arecibo H I observations of 298 late-type galaxies in the Virgo Cluster drawn mostly from the new catalog of Binggeli, Sandage, and Tammann (1985) are presented. Two hundred seventeen of these constitute a magnitude-limited 'complete sample' of such galaxies, types Sdm through Im and BCD. Sixty-one percent of this 'complete sample' was detected, greatly enhancing the store of redshifts and H I masses for such galaxies in the Virgo Cluster. For detected galaxies, heliocentric velocities, 50 percent profile widths, and single-beam fluxes are presented. For those that escaped detection, upper limits are computed to the flux appropriate to the redshift range (-600 to +3000 km/s).

  1. Statistics and properties of H II regions in a sample of grand design galaxies I. Luminosity functions.

    NASA Astrophysics Data System (ADS)

    Rozas, M.; Beckman, J. E.; Knapen, J. H.

    1996-03-01

    We present new high quality continuum-subtracted Hα images of the grand-design galaxies NGC 157, NGC 3631, NGC 6764 and NGC 6951. We have determined the positions, angular sizes, and fluxes of their individual HII regions, and describe statistical properties of the HII region samples. We construct luminosity functions for all the HII regions in the disc and separately for arm and interarm zones for each galaxy. The slopes of the luminosity functions for the complete sample agree well with values published for other spiral galaxies of comparable morphological type. For three galaxies we determined the slopes of the luminosity functions for the spiral arm and interarm zones separately. We find that for NGC 157, NGC 3631, and NGC 6951 these slopes are equal within the errors of determination. We compare our results to those found from earlier work, specifically for M51 and NGC 6814, and discuss implications for massive star forming processes.

  2. STRIDES: Galaxy Evolution over Cosmic Time from new samples of Gravitationally Lensed Quasars

    NASA Astrophysics Data System (ADS)

    Agnello, Adriano; Treu, Tommaso

    2015-08-01

    When a quasar is gravitationally lensed by a galaxy, its multiple images show light-curves that are offset by awell defined time delay, which depends on the mass profile of the lens and on cosmological distances to the lens and the source. By measuring the time-delay and accurately modelling the deflector's mass profile, this provides one-step measurements of cosmological distances to objects at redshift $z\\sim1,$ whence the cosmological parameters (primarily $H_0$). One can turn this argument around and learn about galaxies instead, or even perform a joint (and less biased) inference. The joint modelling of the lens, the source structure and time-variability implies that the DM halos of lens galaxies at z~0.4-1 and the source properties of quasars and their hosts at z~1-2are inferred, besides information on cosmology that is complementary to other low-redshift probes such as SN Ia and BAO.A large (N~100) sample of lensed quasars will be transformative in this sense, as these systems are rare on the sky.I will describe our STRIDES[*] searches in the Dark Energy Survey, aiming at 120 previously unknown lensed quasars brighter than i=21. Candidates have been selected with a variety of data mining techniques and flagged for follow-up (on spectroscopy, high-resolution imaging and lightcurve variability), which will take place in the following months. I will also cover recent modelling development of already monitored lenses within our collaboration, including a sharp multi-band reconstruction of the sources and use of stellar kinematics to ensure unbiased uncertainties on the lens mass profiles.This will lead to: (i) percent-level uncertainties on cosmological parameters(ii) insight on the coevolution of quasars and their host galaxies throughout cosmic time, up to z~2(iii) a quantative description of dark matter density profiles and the substructure content in massive galaxies up to z~1.[*] strides.physics.ucsb.edu

  3. Testing different AGN tracers on a local sample of Seyfert galaxies

    NASA Astrophysics Data System (ADS)

    Pozzi, F.

    2016-08-01

    I will present our new study on a local sample of Seyfert galaxies selected at 12 micron. This sample, given its plenty of information, both photometric and spectroscopic, is a perfect sample to compare, from a statistical point of view, different AGN selection criteria, and AGN derived intrinsic properties. In detail, I will compare AGN activity derived from SED-fitting technique, X-ray luminosity and AGN activity traced by high excitation IR lines, like [NeV] and [OIV]. Moreover, for one particular obscured X-ray Compton-thick source, thanks also to the availability of ALMA data, I will derive a self-consistent overview of the physics behind the emission in different bands,by taking advantage of the photoionization code CLOUDY.

  4. INFRARED AND ULTRAVIOLET STAR FORMATION IN BRIGHTEST CLUSTER GALAXIES IN THE ACCEPT SAMPLE

    SciTech Connect

    Hoffer, Aaron S.; Donahue, Megan; Hicks, Amalia; Barthelemy, R. S. E-mail: donahue@pa.msu.edu E-mail: ramon.s.barthelemy@wmich.edu

    2012-03-01

    We present infrared (IR) and ultraviolet (UV) photometry for a sample of brightest cluster galaxies (BCGs). The BCGs are from a heterogeneous but uniformly characterized sample, the Archive of Chandra Cluster Entropy Profile Tables (ACCEPT), of X-ray galaxy clusters from the Chandra X-ray telescope archive with published gas temperature, density, and entropy profiles. We use archival Galaxy Evolution Explorer (GALEX), Spitzer Space Telescope, and Two Micron All Sky Survey (2MASS) observations to assemble spectral energy distributions (SEDs) and colors for BCGs. We find that while the SEDs of some BCGs follow the expectation of red, dust-free old stellar populations, many exhibit signatures of recent star formation in the form of excess UV or mid-IR emission, or both. We establish a mean near-UV (NUV) to 2MASS K color of 6.59 {+-} 0.34 for quiescent BCGs. We use this mean color to quantify the UV excess associated with star formation in the active BCGs. We use both fits to a template of an evolved stellar population and library of starburst models and mid-IR star formation relations to estimate the obscured star formation rates (SFRs). We show that many of the BCGs in X-ray clusters with low central gas entropy exhibit enhanced UV (38%) and mid-IR emission (43%) from 8 to 160 {mu}m, above that expected from an old stellar population. These excesses are consistent with ongoing star formation activity in the BCG, star formation that appears to be enabled by the presence of high-density, X-ray-emitting intergalactic gas in the core of the cluster of galaxies. This hot, X-ray-emitting gas may provide the enhanced ambient pressure and some of the fuel to trigger star formation. This result is consistent with previous works that showed that BCGs in clusters with low central gas entropies host H{alpha} emission-line nebulae and radio sources, while clusters with high central gas entropy exhibit none of these features. GALEX UV and Spitzer mid-IR measurements combined

  5. SPIDER - I. Sample and galaxy parameters in the grizYJHK wavebands

    NASA Astrophysics Data System (ADS)

    La Barbera, F.; de Carvalho, R. R.; de La Rosa, I. G.; Lopes, P. A. A.; Kohl-Moreira, J. L.; Capelato, H. V.

    2010-11-01

    This is the first paper of a series presenting the Spheroids Panchromatic Investigation in Different Environmental Regions (SPIDER). The sample of spheroids consists of 5080 bright (Mr < -20) early-type galaxies (ETGs), in the redshift range of 0.05 to 0.095, with optical (griz) photometry and spectroscopy from the Sloan Digital Sky Survey Data Release 6 (SDSS-DR6) and near-infrared (YJHK) photometry from the UKIRT Infrared Deep Sky Survey-Large Area Survey (UKIDSS-LAS) (DR4). We describe how homogeneous photometric parameters (galaxy colours and structural parameters) are derived using grizYJHK wavebands. We find no systematic steepening of the colour-magnitude relation when probing the baseline from g - r to g - K, implying that internal colour gradients drive most of the mass-metallicity relation in ETGs. As far as structural parameters are concerned we find that the mean effective radius of ETGs smoothly decreases, by 30 per cent, from g through K, while no significant dependence on waveband is detected for the axial ratio, Sersic index and a4 parameters. Furthermore, velocity dispersions are remeasured for all the ETGs using STARLIGHT and compared to those obtained by SDSS. The velocity dispersions are rederived using a combination of simple stellar population models as templates, hence accounting for the kinematics of different galaxy stellar components. We compare our (2DPHOT) measurements of total magnitude, effective radius and mean surface brightness with those obtained as part of the SDSS pipeline (PHOTO). Significant differences are found and reported, including comparisons with a third and independent part. A full characterization of the sample completeness in all wavebands is presented, establishing the limits of application of the characteristic parameters presented here for the analysis of the global scaling relations of ETGs.

  6. COSMIC EVOLUTION OF BLACK HOLES AND SPHEROIDS. V. THE RELATION BETWEEN BLACK HOLE MASS AND HOST GALAXY LUMINOSITY FOR A SAMPLE OF 79 ACTIVE GALAXIES

    SciTech Connect

    Park, Daeseong; Woo, Jong-Hak; Bennert, Vardha N.; Treu, Tommaso; Auger, Matthew W.; Malkan, Matthew A. E-mail: woo@astro.snu.ac.kr E-mail: vbennert@calpoly.edu E-mail: malkan@astro.ucla.edu

    2015-02-01

    We investigate the cosmic evolution of the black hole (BH) mass-bulge luminosity relation using a sample of 52 active galaxies at z ∼ 0.36 and z ∼ 0.57 in the BH mass range of 10{sup 7.4}-10{sup 9.1} M {sub ☉}. By consistently applying multicomponent spectral and structural decomposition to high-quality Keck spectra and high-resolution Hubble Space Telescope images, BH masses (M {sub BH}) are estimated using the Hβ broad emission line combined with the 5100 Å nuclear luminosity, and bulge luminosities (L {sub bul}) are derived from surface photometry. Comparing the resulting M {sub BH} – L {sub bul} relation to local active galaxies and taking into account selection effects, we find evolution of the form M {sub BH}/L {sub bul}∝(1 + z){sup γ} with γ = 1.8 ± 0.7, consistent with BH growth preceding that of the host galaxies. Including an additional sample of 27 active galaxies with 0.5 < z < 1.9 taken from the literature and measured in a consistent way, we obtain γ = 0.9 ± 0.7 for the M {sub BH} – L {sub bul} relation and γ = 0.4 ± 0.5 for the M {sub BH}-total host galaxy luminosity (L {sub host}) relation. The results strengthen the findings from our previous studies and provide additional evidence for host galaxy bulge growth being dominated by disk-to-bulge transformation via minor mergers and/or disk instabilities.

  7. Companions to isolated elliptical galaxies: revisiting the Bothun-Sullivan (1977) sample using the NASA/IPAC extragalactic database

    NASA Technical Reports Server (NTRS)

    Madore, B. F.; Freedman, W. L.; Bothun, G. D.

    2002-01-01

    We investigate the number of physical companion galaxies for a sample of relatively isolated elliptical galaxies. The NASA/IPAC Extragalactic Database (NED) has been usedto reinvestigate the incidence of satellite galaxies for a sample of 34 elliptical galaxies, firstinvestigated by Bothun & Sullivan (1977) using a visual inspection of Palomar Sky Survey prints out to a projected search radius of 75 kpc. We have repeated their original investigation usingdata cataloged data in NED. Nine of these ellipticals appear to be members of galaxy clusters:the remaining sample of 25 galaxies reveals an average of +1.0 f 0.5 apparent companions per galaxy within a projected search radius of 75 kpc, in excess of two equal-area comparisonregions displaced by 150-300 kpc. This is nearly an order of magnitude larger than the +0.12+/- 0.42 companions/galaxy found by Bothun & Sullivan for the identical sample. Making use of published radial velocities, mostly available since the completion of the Bothun-Sullivan study,identifies the physical companions and gives a somewhat lower estimate of +0.4 companions per elliptical. This is still a factor of 3x larger than the original statistical study, but giventhe incomplete and heterogeneous nature of the survey redshifts in NED, it still yields a firmlower limit on the number (and identity) of physical companions. An expansion of the searchradius out to 300 kpc, again restricted to sampling only those objects with known redshifts in NED, gives another lower limit of 4.3 physical companions per galaxy. (Excluding fiveelliptical galaxies in the Fornax cluster this average drops to 3.5 companions per elliptical.)These physical companions are individually identified and listed, and the ensemble-averagedradial density distribution of these associated galaxies is presented. For the ensemble, the radial density distribution is found to have a fall-off consistent with p c( R^-0.5 out to approximately150 kpc. For non-Fornax cluster companions the

  8. Companions to isolated elliptical galaxies: revisiting the Bothun-Sullivan (1977) sample using the NASA/IPAC extragalactic database

    NASA Technical Reports Server (NTRS)

    Madore, B. F.; Freedman, W. L.; Bothun, G. D.

    2002-01-01

    We investigate the number of physical companion galaxies for a sample of relatively isolated elliptical galaxies. The NASA/IPAC Extragalactic Database (NED) has been usedto reinvestigate the incidence of satellite galaxies for a sample of 34 elliptical galaxies, firstinvestigated by Bothun & Sullivan (1977) using a visual inspection of Palomar Sky Survey prints out to a projected search radius of 75 kpc. We have repeated their original investigation usingdata cataloged data in NED. Nine of these ellipticals appear to be members of galaxy clusters:the remaining sample of 25 galaxies reveals an average of +1.0 f 0.5 apparent companions per galaxy within a projected search radius of 75 kpc, in excess of two equal-area comparisonregions displaced by 150-300 kpc. This is nearly an order of magnitude larger than the +0.12+/- 0.42 companions/galaxy found by Bothun & Sullivan for the identical sample. Making use of published radial velocities, mostly available since the completion of the Bothun-Sullivan study,identifies the physical companions and gives a somewhat lower estimate of +0.4 companions per elliptical. This is still a factor of 3x larger than the original statistical study, but giventhe incomplete and heterogeneous nature of the survey redshifts in NED, it still yields a firmlower limit on the number (and identity) of physical companions. An expansion of the searchradius out to 300 kpc, again restricted to sampling only those objects with known redshifts in NED, gives another lower limit of 4.3 physical companions per galaxy. (Excluding fiveelliptical galaxies in the Fornax cluster this average drops to 3.5 companions per elliptical.)These physical companions are individually identified and listed, and the ensemble-averagedradial density distribution of these associated galaxies is presented. For the ensemble, the radial density distribution is found to have a fall-off consistent with p c( R^-0.5 out to approximately150 kpc. For non-Fornax cluster companions the

  9. Bulgeless Galaxies at Intermediate Redshift: Sample Selection, Color Properties, and the Existence of Powerful Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Bizzocchi, Luca; Filho, Mercedes E.; Leonardo, Elvira; Grossi, Marco; Griffith, Roger L.; Afonso, José; Fernandes, Cristina; Retrê, João; Anton, Sonia; Bell, Eric F.; Brinchmann, Jarle; Henriques, Bruno; Lobo, Catarina; Messias, Hugo

    2014-02-01

    We present a catalog of bulgeless galaxies, which includes 19,225 objects selected in four of the deepest, largest multi-wavelength data sets available—COSMOS, AEGIS, GEMS, and GOODS—at intermediate redshift (0.4 <= z <= 1.0). The morphological classification was provided by the Advanced Camera for Surveys General Catalog (ACS-GC), which used publicly available data obtained with the ACS instrument on the Hubble Space Telescope. Rest-frame photometric quantities were derived using kcorrect. We analyze the properties of the sample and the evolution of pure-disk systems with redshift. Very massive [log (M sstarf/M ⊙) > 10.5] bulgeless galaxies contribute to ~30% of the total galaxy population number density at z >= 0.7, but their number density drops substantially with decreasing redshift. We show that only a negligible fraction of pure disks appear to be quiescent systems, and red sequence bulgeless galaxies show indications of dust-obscured star formation. X-ray catalogs were used to search for X-ray emission within our sample. After visual inspection and detailed parametric morphological fitting we identify 30 active galactic nuclei (AGNs) that reside in galaxies without a classical bulge. The finding of such peculiar objects at intermediate redshift shows that while AGN growth in merger-free systems is a rare event (0.2% AGN hosts in this sample of bulgeless galaxies), it can indeed happen relatively early in the history of the universe.

  10. Bulgeless galaxies at intermediate redshift: Sample selection, color properties, and the existence of powerful active galactic nuclei

    SciTech Connect

    Bizzocchi, Luca; Leonardo, Elvira; Grossi, Marco; Afonso, José; Fernandes, Cristina; Retrê, João; Filho, Mercedes E.; Lobo, Catarina; Griffith, Roger L.; Anton, Sonia; Bell, Eric F.; Brinchmann, Jarle; Henriques, Bruno; Messias, Hugo

    2014-02-10

    We present a catalog of bulgeless galaxies, which includes 19,225 objects selected in four of the deepest, largest multi-wavelength data sets available—COSMOS, AEGIS, GEMS, and GOODS—at intermediate redshift (0.4 ≤ z ≤ 1.0). The morphological classification was provided by the Advanced Camera for Surveys General Catalog (ACS-GC), which used publicly available data obtained with the ACS instrument on the Hubble Space Telescope. Rest-frame photometric quantities were derived using kcorrect. We analyze the properties of the sample and the evolution of pure-disk systems with redshift. Very massive [log (M {sub *}/M {sub ☉}) > 10.5] bulgeless galaxies contribute to ∼30% of the total galaxy population number density at z ≥ 0.7, but their number density drops substantially with decreasing redshift. We show that only a negligible fraction of pure disks appear to be quiescent systems, and red sequence bulgeless galaxies show indications of dust-obscured star formation. X-ray catalogs were used to search for X-ray emission within our sample. After visual inspection and detailed parametric morphological fitting we identify 30 active galactic nuclei (AGNs) that reside in galaxies without a classical bulge. The finding of such peculiar objects at intermediate redshift shows that while AGN growth in merger-free systems is a rare event (0.2% AGN hosts in this sample of bulgeless galaxies), it can indeed happen relatively early in the history of the universe.

  11. The Circumgalactic Medium of Submillimeter Galaxies. I. First Results from a Radio-identified Sample

    NASA Astrophysics Data System (ADS)

    Fu, Hai; Hennawi, J. F.; Prochaska, J. X.; Mutel, R.; Casey, C.; Cooray, A.; Kereš, D.; Zhang, Z.-Y.; Clements, D.; Isbell, J.; Lang, C.; McGinnis, D.; Michałowski, M. J.; Mooley, K.; Perley, D.; Stockton, A.; Thompson, D.

    2016-11-01

    We present the first results from an ongoing survey to characterize the circumgalactic medium (CGM) of massive high-redshift galaxies detected as submillimeter galaxies (SMGs). We constructed a parent sample of 163 SMG-QSO pairs with separations less than ˜36″ by cross-matching far-infrared-selected galaxies from Herschel with spectroscopically confirmed QSOs. The Herschel sources were selected to match the properties of the SMGs. We determined the sub-arcsecond positions of six Herschel sources with the Very Large Array and obtained secure redshift identification for three of those with near-infrared spectroscopy. The QSO sightlines probe transverse proper distances of 112, 157, and 198 kpc at foreground redshifts of 2.043, 2.515, and 2.184, respectively, which are comparable to the virial radius of the ˜1013 M ⊙ halos expected to host SMGs. High-quality absorption-line spectroscopy of the QSOs reveals systematically strong H i Lyα absorption around all three SMGs, with rest-frame equivalent widths of ˜2-3 Å. However, none of the three absorbers exhibit compelling evidence for optically thick H i gas or metal absorption, in contrast to the dominance of strong neutral absorbers in the CGM of luminous z ˜ 2 QSOs. The low covering factor of optically thick H i gas around SMGs tentatively indicates that SMGs may not have as prominent cool gas reservoirs in their halos as the coeval QSOs and that they may inhabit less massive halos than previously thought.

  12. Characterization and Modeling of Contamination for Lyman Break Galaxy Samples at High Redshift

    NASA Astrophysics Data System (ADS)

    Vulcani, Benedetta; Trenti, Michele; Calvi, Valentina; Bouwens, Rychard; Oesch, Pascal; Stiavelli, Massimo; Franx, Marijn

    2017-02-01

    The selection of high-redshift sources from broadband photometry using the Lyman-break galaxy (LBG) technique is a well established methodology, but the characterization of its contamination for the faintest sources is still incomplete. We use the optical and near-IR data from four (ultra)deep Hubble Space Telescope legacy fields to investigate the contamination fraction of LBG samples at z˜ 5{--}8 selected using a color-color method. Our approach is based on characterizing the number count distribution of interloper sources, that is, galaxies with colors similar to those of LBGs, but showing detection at wavelengths shorter than the spectral break. Without sufficient sensitivity at bluer wavelengths, a subset of interlopers may not be properly classified, and contaminate the LBG selection. The surface density of interlopers in the sky gets steeper with increasing redshift of LBG selections. Since the intrinsic number of dropouts decreases significantly with increasing redshift, this implies increasing contamination from misclassified interlopers with increasing redshift, primarily by intermediate redshift sources with unremarkable properties (intermediate ages, lack of ongoing star formation and low/moderate dust content). Using Monte-Carlo simulations, we estimate that the CANDELS deep data have contamination induced by photometric scatter increasing from ˜ 2 % at z˜ 5 to ˜ 6 % at z˜ 8 for a typical dropout color ≥slant 1 mag, with contamination naturally decreasing for a more stringent dropout selection. Contaminants are expected to be located preferentially near the detection limit of surveys, ranging from 0.1 to 0.4 contaminants per arcmin2 at {J}125 = 30, depending on the field considered. This analysis suggests that the impact of contamination in future studies of z> 10 galaxies needs to be carefully considered.

  13. A search at the millijansky level for milli-arcsecond cores in a complete sample of radio galaxies

    NASA Technical Reports Server (NTRS)

    Wehrle, A. E.; Preston, R. A.; Meier, D. L.; Gorenstein, M. V.; Shapiro, I. I.; Rogers, A. E. E.; Rius, A.

    1984-01-01

    A complete sample of 26 extended radio galaxies was observed at 2.29 GHz with the Mark III VLBI system. The fringe spacing was about 3 milli-arcsec, and the detection limit was about 2 millijanskys. Half of the galaxies were found to possess milli-arcsec radio cores. In all but three sources, the nuclear flux density was less than 0.04 of the total flux density. Galaxies with high optical luminosity (less than -21.2) were more likely than less luminous galaxies to contain a detectable milliparcsec radio core (69 percent vs. 20 percent). For objects with arcsec cores, 80 percent were found to have a milli-arcsec core, even though the milli-arcsec object did not always contribute the greater part of the arcsec flux density.

  14. Disturbed galaxy clusters are more abundant in an X-ray volume-limited sample

    NASA Astrophysics Data System (ADS)

    Chon, Gayoung; Böhringer, Hans

    2017-10-01

    X-ray observations of clusters of galaxies have been used to study the large-scale structure of our Universe and to test cosmological models. In such studies it is critical to understand the unique survey selection function correctly. In comparison to the cluster detection by the Sunyaev-Zel'dovich effect (SZE), it has been shown that X-ray observations preferentially detect clusters that have cool cores or are more relaxed as opposed to more disturbed or non-cool-core clusters found in SZE surveys. In this Letter we show that it is not the means of detection, X-rays or SZE, but the sampling strategy, flux-limited or volume-limited surveying, that makes the difference. XMM-Newton observations of the REFLEX clusters in our Volume-Limited Sample (ReVols) show that the fraction of disturbed clusters, determined by the third moment of the power ratios and by centre shifts, is larger by about a factor of two than that of relaxed clusters. In contrast, two flux-limited cluster samples that can be constructed out of ReVols contain more comparable fractions of disturbed and relaxed clusters, which differ by only ten per cent. We use the ratio of the luminosity measured within r500 to that measured in the same aperture without the core region as an indicator for a cool core and find that the number of non-cool-core clusters is comparable to or larger than that of the cool-core clusters in ReVols. In addition, we show that the X-ray luminosity distributions of the disturbed and relaxed clusters are distinctly different, and on average, a displacement of 60% in luminosity is required to match two distributions. Therefore the larger fraction of relaxed and cool-core clusters reported in previous X-ray surveys does not result from the X-ray detection per se, but from the fact that these samples were constructed from flux-limited surveys. Our findings also suggest that the Malmquist bias correction used in cosmological studies with X-ray galaxy clusters could be improved by

  15. A SAMPLE OF SEYFERT-2 GALAXIES WITH ULTRALUMINOUS GALAXY-WIDE NARROW-LINE REGIONS: QUASAR LIGHT ECHOES?

    SciTech Connect

    Schirmer, M.; Diaz, R.; Levenson, N. A.; Winge, C.; Holhjem, K.

    2013-01-20

    We report the discovery of Seyfert-2 galaxies in SDSS-DR8 with galaxy-wide, ultraluminous narrow-line regions (NLRs) at redshifts z = 0.2-0.6. With a space density of 4.4 Gpc{sup -3} at z {approx} 0.3, these 'green beans' (GBs) are amongst the rarest objects in the universe. We are witnessing an exceptional and/or short-lived phenomenon in the life cycle of active galactic nuclei (AGNs). The main focus of this paper is on a detailed analysis of the GB prototype galaxy J2240-0927 (z = 0.326). Its NLR extends over 26 Multiplication-Sign 44 kpc and is surrounded by an extended NLR. With a total [O III] {lambda}5008 luminosity of (5.7 {+-} 0.9) Multiplication-Sign 10{sup 43} erg s{sup -1}, this is one of the most luminous NLRs known around any type-2 galaxy. Using VLT/XSHOOTER, we show that the NLR is powered by an AGN, and we derive resolved extinction, density, and ionization maps. Gas kinematics is disturbed on a global scale, and high-velocity outflows are absent or faint. This NLR is unlike any other NLR or extended emission line region known. Spectroscopy with Gemini/GMOS reveals extended, high-luminosity [O III] emission also in other GBs. WISE 24 {mu}m luminosities are 5-50 times lower than predicted by the [O III] fluxes, suggesting that the NLRs reflect earlier, very active quasar states that have strongly subsided in less than a galaxy's light-crossing time. These light echoes, or ionization echoes, are about 100 times more luminous than any other such echo known to date. X-ray data are needed for photoionization modeling and to verify the light echoes.

  16. Spectroscopy and Photometry of Elliptical Galaxies. VI. Sample Selection and Data Summary: Erratum

    NASA Astrophysics Data System (ADS)

    Faber, S. M.; Wegner, Gary; Burstein, David; Davies, Roger L.; Dressler, Alan; Lynden-Bell, D.; Terlevich, R. J.

    1989-09-01

    In the paper "Spectroscopy and Photometry of Elliptical Galaxies. VI. Sample Selection and Data Summary" by S. M. Faber, G. Wegner, D. Burstein, Roger L. Davies, A. Dressler, D. Lynden-Bell, and R. J. Terlevich (Ap. J. Suppl., 69, 763 [1989] the (B-V)_0_ coIors listed in Table 1, column (9), are incorrectly identified in the text as coming from an average of all photoelectric observations made in apertures <=67" in diameter. The (B - V)_0_ colors in apertures <=67" in diameter are given in a paper by David Burstein, Roger L. Davies, Alan Dressler, S. M. Faber, Remington P. S. Stone, Donald Lynden-Bell, Roberto J. Terlevich, and Gary Wegner (Ap. J. Suppl., 64, 601 [1987]). The (B-V)_0_ colors listed in Tab1e 1 in the present paper come from an average of all photoelectric observations made in apertures <=30" in diameter. The number of observations per galaxy given in Table 1 also refers to those made in apertures <= 30" in diameter. In both cases, the colors given are corrected for the same Galactic extinction and cosmological effects. The incorrect identification of the aperture size of the (B-V)_0_ colors has no other effect on this paper. We thank Marijn Franx for first pointing out the difference in the (B - V)0 colors listed in the present paper and Burstein et al. (1987).

  17. The ESO Slice Project (ESP) galaxy redshift survey. III. The sample

    NASA Astrophysics Data System (ADS)

    Vettolani, G.; Zucca, E.; Merighi, R.; Mignoli, M.; Proust, D.; Zamorani, G.; Cappi, A.; Guzzo, L.; Maccagni, D.; Ramella, M.; Stirpe, G. M.; Blanchard, A.; Cayatte, V.; Collins, C.; MacGillivray, H.; Maurogordato, S.; Scaramella, R.; Balkowski, C.; Chincarini, G.; Felenbok, P.

    1998-06-01

    The ESO Slice Project (ESP) is a galaxy redshift survey extending over about 23 square degrees, in a region near the South Galactic Pole. The survey is ~ 85% complete to the limiting magnitude b_J=19.4 and consists of 3342 galaxies with redshift determination. The ESP survey is intermediate between shallow, wide angle samples and very deep, one-dimensional pencil beams; the spanned volume is ~ 5 \\ 10(4) \\htre at the sensitivity peak (z ~ 0.1). In this paper we present the description of the observations and of the data reduction, the ESP redshift catalogue and the analysis of the quality of the velocity determinations. based on observations collected at the European Southern Observatory, La Silla, Chile. Table 3 is only available (and Table 2 is also available) in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

  18. The ESO Slice Project [ESP] galaxy redshift survey. V. Evidence for a D=3 sample dimensionality

    NASA Astrophysics Data System (ADS)

    Scaramella, R.; Guzzo, L.; Zamorani, G.; Zucca, E.; Balkowski, C.; Blanchard, A.; Cappi, A.; Cayatte, V.; Chincarini, G.; Collins, C.; Fiorani, A.; Maccagni, D.; MacGillivray, H.; Maurogordato, S.; Merighi, R.; Mignoli, M.; Proust, D.; Ramella, M.; Stirpe, G. M.; Vettolani, G.

    1998-06-01

    The issue of the approximate isotropy and homogeneity of the observable universe is one of the major topics in modern Cosmology: the common use of the Friedmann-Robertson-Walker [FWR] metric relies on these assumptions. Therefore, results conflicting with the ``canonical'' picture would be of the utmost importance. In a number of recent papers it has been suggested that strong evidence of a fractal distribution with dimension D =~ 2 exists in several samples, including Abell clusters [ACO] and galaxies from the ESO Slice Project redshift survey [ESP]. Here we report the results of an independent analysis of the radial density run, N(samples the dimensionality of the ESP sample is D ~ 3, and the value D = 2 is always excluded at the level of at least five (bootstrap) standard deviations. The only way in which we reproduce D ~ 2 is by both unphysically ignoring the galaxy k-correction and using Euclidean rather than FRW cosmological distances. In the cluster case the problems related to the choice of metrics and k-correction are much lessened, and we find that ACO clusters have DACO = 3.07 +/- 0.18 and DACO = 2.93 +/- 0.15 for richness class R >= 1 and R >= 0, respectively. Therefore D=2 is excluded with high significance also for the cluster data. based on observations collected at the European Southern Observatory, La Silla, Chile.

  19. Herschel-ATLAS: Toward a Sample of ~1000 Strongly Lensed Galaxies

    NASA Astrophysics Data System (ADS)

    González-Nuevo, J.; Lapi, A.; Fleuren, S.; Bressan, S.; Danese, L.; De Zotti, G.; Negrello, M.; Cai, Z.-Y.; Fan, L.; Sutherland, W.; Baes, M.; Baker, A. J.; Clements, D. L.; Cooray, A.; Dannerbauer, H.; Dunne, L.; Dye, S.; Eales, S.; Frayer, D. T.; Harris, A. I.; Ivison, R.; Jarvis, M. J.; Michałowski, M. J.; López-Caniego, M.; Rodighiero, G.; Rowlands, K.; Serjeant, S.; Scott, D.; van der Werf, P.; Auld, R.; Buttiglione, S.; Cava, A.; Dariush, A.; Fritz, J.; Hopwood, R.; Ibar, E.; Maddox, S.; Pascale, E.; Pohlen, M.; Rigby, E.; Smith, D.; Temi, P.

    2012-04-01

    While the selection of strongly lensed galaxies (SLGs) with 500 μm flux density S 500 > 100 mJy has proven to be rather straightforward, for many applications it is important to analyze samples larger than the ones obtained when confining ourselves to such a bright limit. Moreover, only by probing to fainter flux densities is it possible to exploit strong lensing to investigate the bulk of the high-z star-forming galaxy population. We describe HALOS (the Herschel-ATLAS Lensed Objects Selection), a method for efficiently selecting fainter candidate SLGs, reaching a surface density of ~= 1.5-2 deg-2, i.e., a factor of about 4-6 higher than that at the 100 mJy flux limit. HALOS will allow the selection of up to ~1000 candidate SLGs (with amplifications μ >~ 2) over the full H-ATLAS survey area. Applying HALOS to the H-ATLAS Science Demonstration Phase field (sime 14.4 deg2) we find 31 candidate SLGs, whose candidate lenses are identified in the VIKING near-infrared catalog. Using the available information on candidate sources and candidate lenses we tentatively estimate a ~= 72% purity of the sample. As expected, the purity decreases with decreasing flux density of the sources and with increasing angular separation between candidate sources and lenses. The redshift distribution of the candidate lensed sources is close to that reported for most previous surveys for lensed galaxies, while that of candidate lenses extends to redshifts substantially higher than found in the other surveys. The counts of candidate SLGs are also in good agreement with model predictions. Even though a key ingredient of the method is the deep near-infrared VIKING photometry, we show that H-ATLAS data alone allow the selection of a similarly deep sample of candidate SLGs with an efficiency close to 50%; a slightly lower surface density (sime 1.45 deg-2) can be reached with a ~70% efficiency. Herschel is an ESA space observatory with science instruments provided by European-led Principal

  20. Variation of the Tully-Fisher relation as a function of the magnitude interval of a sample of galaxies

    NASA Astrophysics Data System (ADS)

    Ruelas-Mayorga, A.; Sánchez, L. J.; Trujillo-Lara, M.; Nigoche-Netro, A.; Echevarría, J.; García, A. M.; Ramírez-Vélez, J.

    2016-10-01

    In this paper we carry out a preliminary study of the dependence of the Tully-Fisher Relation (TFR) with the width and intensity level of the absolute magnitude interval of a limited sample of 2411 galaxies taken from Mathewson and Ford (Astrophys. J. Suppl. Ser. 107:97, 1996). The galaxies in this sample do not differ significantly in morphological type, and are distributed over an ˜ 11-magnitude interval (-24.4 < I < -13.0). We take as directives the papers by Nigoche-Netro et al. (Astron. Astrophys. 491:731, 2008; Mon. Not. R. Astron. Soc. 392:1060, 2009; Astron. Astrophys. 516:96, 2010) in which they study the dependence of the Kormendy (KR), the Fundamental Plane (FPR) and the Faber-Jackson Relations (FJR) with the magnitude interval within which the observed galaxies used to derive these relations are contained. We were able to characterise the behaviour of the TFR coefficients (α, β ) with respect to the width of the magnitude interval as well as with the brightness of the galaxies within this magnitude interval. We concluded that the TFR for this specific sample of galaxies depends on observational biases caused by arbitrary magnitude cuts, which in turn depend on the width and intensity of the chosen brightness levels.

  1. Physical properties from VLT spectroscopy of a sample of star-forming dwarf galaxies at intermediate redshift

    NASA Astrophysics Data System (ADS)

    Rodríguez-Muñoz, L.; Gallego, J.; Pérez-González, P. G.; Tresse, L.; Gil de Paz, A.; Barro, G.; Villar, V.; Le Fèvre, O.

    2013-05-01

    Dwarf galaxies remain as one of the most important and missing pieces of the great puzzle of formation and evolution of galaxies. Due to their low luminosities, their study has been mainly biased to the local universe or clusters, which hampers our knowledge of their redshift of formation and properties along the cosmological time, strong observational tests to recent models of formation and evolution of low-mass galaxies. Using the multiwavelength database RAINBOW, that provides photometric redshifts and masses estimations, we selected a representative sample of dwarf galaxies in the Chandra Deep Field-South (CDFS) within the redshift range 0.3sample, carried out using own spectra obtained with the spectrograph VIMOS at the VLT-ESO. These observational data provide spectroscopic redshifts and measurements of emission lines such as [OII]3727Å , Hβ, [OIII]4958,5007Å , and Hα, from which we estimate the physical properties of our dwarf galaxy sample.

  2. Kinematic modeling of the galaxy. II - Two samples of high proper motion stars

    NASA Technical Reports Server (NTRS)

    Casertano, Stefano; Ratnatunga, Kavan U.; Bahcall, John N.

    1990-01-01

    The paper analyzes two independent surveys, due to Fouts and Sandage and to Carney and Latham, of high proper motion stars with photoelectric photometry and line-of-sight velocity information. A purely kinematic study of both samples indicates that a two-component classical (disk + spheroid) model of the Galaxy is inadequate to represent the kinematics of stars in the solar neighborhood. A component with intermediate kinematic properties (old disk) is required. An asymmetric drift of 50 + or - 15 km/s and principal velocity dispersions of (66, 37, 38) + or - 10 km/s are determined, in good agreement with the results of the metallicity-based analysis of Sandage and Fouts and of Carney and collaborators. The density of this component is poorly constrained, and is 10 percent + or - 5 percent of the local disk density for the same color range; the scale height is less than 1 kpc.

  3. VizieR Online Data Catalog: Observed sample of z~0.7 massive galaxies (Gallazzi+, 2014)

    NASA Astrophysics Data System (ADS)

    Gallazzi, A.; Bell, E. F.; Zibetti, S.; Brinchmann, J.; Kelson, D. D.

    2017-07-01

    The sample has been selected from the COMBO-17 catalog of the Extended Chandra Deep Field South (E-CDFS) survey (Wolf et al. 2004A&A...421..913W, Cat. II/253; see also Section 2.4.1) to have photometric redshift (or spectroscopic when available) in the range 0.65=sample of 717 galaxies (of which 200 already had a spectroscopic redshift from the literature at the time at which the targets were selected). We further restrict the selection to galaxies with apparent R-band magnitude R<22.7, which allows sampling the red sequence down to its completeness limit of 3x1010 Mȯ at this redshift (Borch et al. 2006A&A...453..869B) and the massive end of the blue cloud. From the so-selected sample of 521 galaxies we observed a final sample of 77 galaxies with a single IMACS mask designed. (1 data file).

  4. A Catalog Sample of Low-mass Galaxies Observed in X-Rays with Central Candidate Black Holes

    NASA Astrophysics Data System (ADS)

    Nucita, A. A.; Manni, L.; De Paolis, F.; Giordano, M.; Ingrosso, G.

    2017-03-01

    We present a sample of X-ray-selected candidate black holes in 51 low-mass galaxies with z ≤ 0.055 and masses up to 1010 M ⊙ obtained by cross-correlating the NASA-SLOAN Atlas with the 3XMM catalog. We have also searched in the available catalogs for radio counterparts of the black hole candidates and find that 19 of the previously selected sources also have a radio counterpart. Our results show that about 37% of the galaxies of our sample host an X-ray source (associated with a radio counterpart) spatially coincident with the galaxy center, in agreement with other recent works. For these nuclear sources, the X-ray/radio fundamental plane relation allows one to estimate the mass of the (central) candidate black holes, which are in the range of 104–2 × 108 M ⊙ (with a median value of ≃3 × 107 M ⊙ and eight candidates having masses below 107 M ⊙). This result, while suggesting that X-ray emitting black holes in low-mass galaxies may have had a key role in the evolution of such systems, makes it even more urgent to explain how such massive objects formed in galaxies. Of course, dedicated follow-up observations both in the X-ray and radio bands, as well as in the optical, are necessary in order to confirm our results.

  5. Mass distribution and Dynamical State of Galaxy Clusters in the LZLS Sample

    NASA Astrophysics Data System (ADS)

    Campusano, L. E.; Cypriano, E. S.; Sodré, L., Jr.; Kneib, J.-P.

    We use the weak gravitational lensing effect to study the mass distribution of a sample of 50 southern Abell clusters (0.05 5 × 1044 erg s-1 observed with ESO-VLT under uniform sky conditions and subarsecond (0.6'') image quality. Their dynamical equibrium is assesed through comparison of the clusters mass estimates made by weak-lensing, velocity-dispersions and X-ray techniques. So far, for 24 clusters (Cypriano et al. 2004), we find: a) the center of their mass and light distributions are coincident for 77% of the sample; b) the elongations of the fitted mass profiles and of the light of the cD galaxies generally match with each other; c) although most of the clusters are found to be in dynamical equilibrium, those with TX ≥ 8 keV (or σv ≥ 1120 km s-1) are the discordant ones. The preliminary bright arc statistics for our whole sample (LZLS) suggests the presence of a cut-off at z˜0.07 which is qualitatively consistent with predictions done in a ΛCDM cosmology (Meneghetti et al. 2003).

  6. Occurrence of Radio Minihalos in a Mass-Limited Sample of Galaxy Clusters

    NASA Technical Reports Server (NTRS)

    Giacintucci, Simona; Markevitch, Maxim; Cassano, Rossella; Venturi, Tiziana; Clarke, Tracy E.; Brunetti, Gianfranco

    2017-01-01

    We investigate the occurrence of radio minihalos-diffuse radio sources of unknown origin observed in the cores of some galaxy clusters-in a statistical sample of 58 clusters drawn from the Planck Sunyaev-Zeldovich cluster catalog using a mass cut (M(sub 500) greater than 6 x 10(exp 14) solar mass). We supplement our statistical sample with a similarly sized nonstatistical sample mostly consisting of clusters in the ACCEPT X-ray catalog with suitable X-ray and radio data, which includes lower-mass clusters. Where necessary (for nine clusters), we reanalyzed the Very Large Array archival radio data to determine whether a minihalo is present. Our total sample includes all 28 currently known and recently discovered radio minihalos, including six candidates. We classify clusters as cool-core or non-cool-core according to the value of the specific entropy floor in the cluster center, rederived or newly derived from the Chandra X-ray density and temperature profiles where necessary (for 27 clusters). Contrary to the common wisdom that minihalos are rare, we find that almost all cool cores-at least 12 out of 15 (80%)-in our complete sample of massive clusters exhibit minihalos. The supplementary sample shows that the occurrence of minihalos may be lower in lower-mass cool-core clusters. No minihalos are found in non-cool cores or "warm cores." These findings will help test theories of the origin of minihalos and provide information on the physical processes and energetics of the cluster cores.

  7. Occurrence of Radio Minihalos in a Mass-limited Sample of Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Giacintucci, Simona; Markevitch, Maxim; Cassano, Rossella; Venturi, Tiziana; Clarke, Tracy E.; Brunetti, Gianfranco

    2017-06-01

    We investigate the occurrence of radio minihalos—diffuse radio sources of unknown origin observed in the cores of some galaxy clusters—in a statistical sample of 58 clusters drawn from the Planck Sunyaev-Zel’dovich cluster catalog using a mass cut (M 500 > 6 × 1014 M ⊙). We supplement our statistical sample with a similarly sized nonstatistical sample mostly consisting of clusters in the ACCEPT X-ray catalog with suitable X-ray and radio data, which includes lower-mass clusters. Where necessary (for nine clusters), we reanalyzed the Very Large Array archival radio data to determine whether a minihalo is present. Our total sample includes all 28 currently known and recently discovered radio minihalos, including six candidates. We classify clusters as cool-core or non-cool-core according to the value of the specific entropy floor in the cluster center, rederived or newly derived from the Chandra X-ray density and temperature profiles where necessary (for 27 clusters). Contrary to the common wisdom that minihalos are rare, we find that almost all cool cores—at least 12 out of 15 (80%)—in our complete sample of massive clusters exhibit minihalos. The supplementary sample shows that the occurrence of minihalos may be lower in lower-mass cool-core clusters. No minihalos are found in non-cool cores or “warm cores.” These findings will help test theories of the origin of minihalos and provide information on the physical processes and energetics of the cluster cores.

  8. Emission Line Properties of Seyfert Galaxies in the 12 μm Sample

    NASA Astrophysics Data System (ADS)

    Malkan, Matthew A.; Jensen, Lisbeth D.; Rodriguez, David R.; Spinoglio, Luigi; Rush, Brian

    2017-09-01

    We present optical and ultraviolet spectroscopic measurements of the emission lines of 81 Seyfert 1 and 104 Seyfert 2 galaxies that comprise nearly all of the IRAS 12 μm AGN sample. We have analyzed the emission-line luminosity functions, reddening, and other diagnostics. For example, the narrow-line regions (NLR) of Seyfert 1 and 2 galaxies do not significantly differ from each other in most of these diagnostics. Combining the Hα/Hβ ratio with a new reddening indicator—the [S ii]6720/[O ii]3727 ratio—we find the average E(B–V) is 0.49 ± 0.35 for type 1 and 0.52 ± 0.26 for type 2 Seyferts. The NLR of Sy 1s has an ionization level insignificantly higher than that of Sy 2s. For the broad-line region (BLR), we find that the C iv equivalent width correlates more strongly with [O iii]/Hβ than with UV luminosity. Our bright sample of local active galaxies includes 22 Seyfert nuclei with extremely weak broad wings in Hα, known as Seyfert 1.9s and 1.8s, depending on whether or not broad Hβ wings are detected. Aside from these weak broad lines, our low-luminosity Seyferts are more similar to the Sy 2s than to Sy 1s. In a BPT diagram, we find that Sy 1.8s and 1.9s overlap the region occupied by Sy 2s. We compare our results on optical emission lines with those obtained by previous investigators, using AGN subsamples from the Sloan Digital Sky Survey. The luminosity functions of forbidden emission lines [O ii]λ3727 Å, [O iii]λ5007 Å, and [S ii]λ6720 Å in Sy 1s and Sy 2s are indistinguishable. They all show strong downward curvature. Unlike the LFs of Seyfert galaxies measured by the Sloan Digital Sky Survey, ours are nearly flat at low luminosities. The larger number of faint Sloan “AGN” is attributable to their inclusion of weakly emitting LINERs and H ii+AGN “composite” nuclei, which do not meet our spectral classification criteria for Seyferts. In an Appendix, we have investigated which emission line luminosities can provide the most reliable

  9. Resolved Gas Kinematics in a Sample of Low-Redshift High Star-Formation Rate Galaxies

    NASA Astrophysics Data System (ADS)

    Varidel, Mathew; Pracy, Michael; Croom, Scott; Owers, Matt S.; Sadler, Elaine

    2016-03-01

    We have used integral field spectroscopy of a sample of six nearby (z 0.01-0.04) high star-formation rate (SFR ˜ 10-40 M_⊙ yr^{-1}) galaxies to investigate the relationship between local velocity dispersion and star-formation rate on sub-galactic scales. The low-redshift mitigates, to some extent, the effect of beam smearing which artificially inflates the measured dispersion as it combines regions with different line-of-sight velocities into a single spatial pixel. We compare the parametric maps of the velocity dispersion with the Hα flux (a proxy for local star-formation rate), and the velocity gradient (a proxy for the local effect of beam smearing). We find, even for these very nearby galaxies, the Hα velocity dispersion correlates more strongly with velocity gradient than with Hα flux-implying that beam smearing is still having a significant effect on the velocity dispersion measurements. We obtain a first-order non parametric correction for the unweighted and flux weighted mean velocity dispersion by fitting a 2D linear regression model to the spaxel-by-spaxel data where the velocity gradient and the Hα flux are the independent variables and the velocity dispersion is the dependent variable; and then extrapolating to zero velocity gradient. The corrected velocity dispersions are a factor of 1.3-4.5 and 1.3-2.7 lower than the uncorrected flux-weighted and unweighted mean line-of-sight velocity dispersion values, respectively. These corrections are larger than has been previously cited using disc models of the velocity and velocity dispersion field to correct for beam smearing. The corrected flux-weighted velocity dispersion values are σ m 20-50 km s-1.

  10. A robust sample of submillimetre galaxies: constraints on the prevalence of dusty, high-redshift starbursts

    NASA Astrophysics Data System (ADS)

    Ivison, R. J.; Smail, Ian; Dunlop, J. S.; Greve, T. R.; Swinbank, A. M.; Stevens, J. A.; Mortier, A. M. J.; Serjeant, S.; Targett, T. A.; Bertoldi, F.; Blain, A. W.; Chapman, S. C.

    2005-12-01

    The modest significance of most sources detected in current (sub)millimetre [(sub)mm] surveys can potentially compromise some analyses due to the inclusion of spurious sources in catalogues typically selected at >=3.0-3.5σ. Here, we develop and apply a dual-survey extraction technique to Submillimetre Common-User Bolometer Array (SCUBA) and Max-Planck Millimetre Bolometer (MAMBO) images of the Lockman Hole. Cut above 5σ, our catalogue of submillimetre galaxies (SMGs) is more robust than previous samples, with a reduced likelihood of real, but faint SMGs (beneath and around the confusion limit) entering via superposition with noise. Our selection technique yields 19 SMGs in an effective area of 165arcmin2, of which we expect at most two to be due to chance superposition of SCUBA and MAMBO noise peaks. The effective flux limit of the survey (~4mJy at ~1mm) is well matched to our deep 1.4-GHz image (σ= 4.6μJybeam-1). The former is sensitive to luminous, dusty galaxies at extreme redshifts whilst the latter probes the z<~ 3 regime. A high fraction of our robust SMGs (~80 per cent) have radio counterparts which, given the ~10per cent contamination by spurious sources, suggests that very distant SMGs (z>> 3) are unlikely to make up more than ~10 per cent of the bright SMG population. This implies that almost all of the S1mm>~ 4mJy SMG population is amenable to study via the deepest current radio imaging. We use these radio counterparts to provide an empirical calibration of the positional uncertainty in SMG catalogues. We then go on to outline the acquisition of redshifts for radio-identified SMGs, from sample selection in the submm, to counterpart selection in the radio and optical/infrared, to slit placement on spectrograph masks. We determine a median of z= 2.05 +/- 0.41 from a sample of six secure redshifts for unambiguous radio-identified submm sources and z= 2.14 +/- 0.27 when we include submm sources with multiple radio counterparts and/or less reliable

  11. The Nonlinear Biasing of the zCOSMOS Galaxies up to z ~ 1 from the 10k Sample

    NASA Astrophysics Data System (ADS)

    Kovač, K.; Porciani, C.; Lilly, S. J.; Marinoni, C.; Guzzo, L.; Cucciati, O.; Zamorani, G.; Iovino, A.; Oesch, P.; Bolzonella, M.; Peng, Y.; Meneux, B.; Zucca, E.; Bardelli, S.; Carollo, C. M.; Contini, T.; Kneib, J.-P.; Le Fèvre, O.; Mainieri, V.; Renzini, A.; Scodeggio, M.; Bongiorno, A.; Caputi, K.; Coppa, G.; de la Torre, S.; de Ravel, L.; Finoguenov, A.; Franzetti, P.; Garilli, B.; Kampczyk, P.; Knobel, C.; Lamareille, F.; Le Borgne, J.-F.; Le Brun, V.; Maier, C.; Mignoli, M.; Pello, R.; Perez-Montero, E.; Pozzetti, L.; Ricciardelli, E.; Silverman, J. D.; Tanaka, M.; Tasca, L. A. M.; Tresse, L.; Vergani, D.; Abbas, U.; Bottini, D.; Cappi, A.; Cassata, P.; Cimatti, A.; Fumana, M.; Koekemoer, A. M.; Leauthaud, A.; Maccagni, D.; McCracken, H. J.; Memeo, P.; Scaramella, R.; Scoville, N. Z.

    2011-04-01

    We use the zCOSMOS galaxy overdensity field to study the biasing of galaxies in the COSMOS field. By comparing the probability distribution function of the galaxy density contrast δ g to the lognormal approximation of the mass density contrast δ, we obtain the mean biasing function b(δ, z, R) between the galaxy and matter overdensity fields and its second moments \\hat{b} and \\tilde{b}. Over the redshift interval 0.4 < z < 1 the conditional mean function langδ g |δrang = b(δ, z, R)δ is of a characteristic shape, requiring nonlinear biasing in the most overdense and underdense regions. Taking into account the uncertainties due to cosmic variance, we do not detect any significant evolution in the langδ g |δrang function, but we do detect a significant redshift evolution in the linear biasing parameter \\hat{b} from 1.23 ± 0.11 at z ~ 0.55 to 1.62 ± 0.14 at z ~ 0.75, for a luminosity-complete sample of MB < -20 - z galaxies. The \\hat{b} parameter does not change significantly with smoothing scale between 8 and 12 h -1 Mpc, but increases systematically with luminosity (at 2σ-3σ significance between the MB < -20.5 - z and MB < -20 - z samples). The nonlinearity parameter \\tilde{b}/ \\hat{b} is offset from unity by at most 2%, with an uncertainty of the same order. The \\tilde{b}/\\hat{b} parameter does not show any significant redshift evolution, dependence on the smoothing scale or on the luminosity. By matching the linear bias of galaxies to the halo bias, we infer that the MB < -20 - z galaxies reside in dark matter halos with a characteristic mass of about (2.6 - 5.6) × 1012 M sun with a small dependence on the adopted bias-mass relation. Our detailed error analysis and comparison with previous studies lead us to conclude that cosmic variance is the main contributor to the differences in the linear bias measured from different surveys. While our results support the general picture of biased galaxy formation up to z ~ 1, the fine-tuning of the galaxy

  12. A Sample of Seyfert-2 Galaxies with Ultraluminous Galaxy-wide Narrow-line Regions: Quasar Light Echoes?

    NASA Astrophysics Data System (ADS)

    Schirmer, M.; Diaz, R.; Holhjem, K.; Levenson, N. A.; Winge, C.

    2013-01-01

    We report the discovery of Seyfert-2 galaxies in SDSS-DR8 with galaxy-wide, ultraluminous narrow-line regions (NLRs) at redshifts z = 0.2-0.6. With a space density of 4.4 Gpc-3 at z ~ 0.3, these "green beans" (GBs) are amongst the rarest objects in the universe. We are witnessing an exceptional and/or short-lived phenomenon in the life cycle of active galactic nuclei (AGNs). The main focus of this paper is on a detailed analysis of the GB prototype galaxy J2240-0927 (z = 0.326). Its NLR extends over 26 × 44 kpc and is surrounded by an extended NLR. With a total [O III] λ5008 luminosity of (5.7 ± 0.9) × 1043 erg s-1, this is one of the most luminous NLRs known around any type-2 galaxy. Using VLT/XSHOOTER, we show that the NLR is powered by an AGN, and we derive resolved extinction, density, and ionization maps. Gas kinematics is disturbed on a global scale, and high-velocity outflows are absent or faint. This NLR is unlike any other NLR or extended emission line region known. Spectroscopy with Gemini/GMOS reveals extended, high-luminosity [O III] emission also in other GBs. WISE 24 μm luminosities are 5-50 times lower than predicted by the [O III] fluxes, suggesting that the NLRs reflect earlier, very active quasar states that have strongly subsided in less than a galaxy's light-crossing time. These light echoes, or ionization echoes, are about 100 times more luminous than any other such echo known to date. X-ray data are needed for photoionization modeling and to verify the light echoes. Based on observations made with ESO Telescopes at the La Silla and Paranal Observatories, Chile. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. Based on observations

  13. Cosmological Implications from an X-Ray Flux-Limited Sample of Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Reiprich, Thomas H.; Böhringer, Hans

    A new X-ray selected/X-ray flux-limited galaxy cluster sample of the 63 X-ray brightest clusters in the sky has been compiled from recent X-ray cluster catalogs based on the ROSAT All-Sky Survey. Cluster masses have been determined homogeneously using mainly ROSAT pointed observations and mostly ASCA gas temperatures, assuming the intracluster gas to be in hydrostatic equilibrium. As the sample is statistically complete, a cluster mass function has been constructed. Integration of the mass function shows that the total gravitating mass contained within the virial radius of clusters with mass larger than 3.5 × 10^{13} h^{-1}_{50} M_⊙ (˜ Hickson group mass) is about two percent of the total mass in a critical density universe, i.e. Ω_{cluster} ≈ 0.02, and about six percent for a normalized matter density Ω_m = 0.3. This implies that by far most of the total mass in the universe resides outside virialized cluster regions. The mass fraction given by Fukugita et al., ApJ, 503, 518 (1998), based on the mass function determined by Bahcall & Cen, ApJ, 407, L49 (1993), is four times higher than the value found here at the corresponding minimum mass. The errors are currently being investigated.

  14. Statistics and properties of H II regions in a sample of grand-design galaxies. II. Physical properties.

    NASA Astrophysics Data System (ADS)

    Rozas, M.; Knapen, J. H.; Beckman, J. E.

    1996-08-01

    We describe statistical properties of complete samples of HII regions in the grand-design spiral galaxies NGC 157, NGC 3631, NGC 6764 and NGC 6951. We use the catalogues of HII regions obtained from high-quality Hα line images by Rozas et al. . Slopes and zero points of diameter distribution functions for these four galaxies coincide well with values published for other galaxies of similar morphological type. We also present density distributions and Hα scale lengths, as well as luminosity-volume and number-luminosity-size relations. The latter relations show evidence for the presence of a population of high luminosity density-bounded HII regions in the spiral arms. We see the change from ionization- to density-bounded HII regions occur clearly at a specific HII region flux level.

  15. Examining the X-ray Properties of Lenticular Galaxies: Rollins S0 X-ray Sample (RS0X)

    NASA Astrophysics Data System (ADS)

    Fuse, Christopher R.; Malespina, Alysa

    2017-01-01

    Lenticular galaxies represent a complex morphology in which many questions remain. The S0 morphology possesses spiral galaxy attributes, such as a disk, while also displaying the luminosity and old stellar population indicative of an elliptical galaxy. The proposed formation mechanisms for lenticulars are also varied, with the absence of gas suggesting a faded spiral and the high masses and luminosities implying a merger formation. The star formation and high-energy emission from a sample of S0s will be used to better understand the properties and formation mechanisms of this unique subset of galaxies.We use the Chandra X-ray Observatory archives cycle 1 - 16 to identify a sample of seventeen lenticular galaxies residing in a variety of environments. Data was analyzed using the CIAO software to produce true color images, radial profiles of the halo gas, gas contours, as well as determine the X-ray luminosities of the point sources and gas.The X-ray gas temperature of the sample S0s varied over a narrow range between 0.61 and 0.96 keV, with one outlier, NGC 4382 at 2.0 keV. The X-ray luminosity of the halo gas varies by four dex. The gas temperatures and X-ray luminosities do not vary by environment, with the majority of sample S0s displaying values of typical elliptical galaxies. The S0 sample is X-ray under-luminous relative to the optical luminosity as compared to the sample of early-type galaxies of Ellis & O’Sullivan (2006).The halo gas exhibited some distinct morphological features, such as multiple X-ray peaks, which may indicate a merger event, and highly concentrated gas, suggesting limited gravitational disturbance. Isolated S0, NGC 4406, displays an asymmetric halo, which could be interpreted as gas stripping. An isolated lenticular experiencing gas redistribution due to gravitational perturbation or a cluster-like medium could be interpreted as NGC 4406 forming in a higher galactic density environment than the field.

  16. AGN heating and ICM cooling in the HIFLUGCS sample of galaxy clusters

    NASA Astrophysics Data System (ADS)

    Mittal, R.; Hudson, D. S.; Reiprich, T. H.; Clarke, T.

    2009-07-01

    Active galactic nuclei (AGN) at the center of galaxy clusters with gas cooling times that are much shorter than the Hubble time have emerged as heating agents powerful enough to prevent further cooling of the intracluster medium (ICM). We carried out an intensive study of the AGN heating-ICM cooling network by comparing various cluster parameters to the integrated radio luminosity of the central AGN, LR, defined as the total synchrotron power between 10 MHz and 15 GHz. This study is based on the HIFLUGCS sample comprising the 64 X-ray brightest galaxy clusters. We adopted the central cooling time, tcool, as the diagnostic to ascertain cooling properties of the HIFLUGCS sample and classify clusters with tcool< 1 Gyr as strong cool-core (SCC) clusters, with 1 Gyr < tcool<7.7 Gyr as weak cool-core (WCC) clusters and with tcool> 7.7 Gyr as non-cool-core (NCC) clusters. We find 48 out of 64 clusters (75%) contain cluster center radio sources (CCRS) cospatial with or within 50 h71-1 kpc of the X-ray peak emission. Furthermore, we find that the probability of finding a CCRS increases from 45% to 67% to 100% for NCC, WCC, and SCC clusters, respectively. We use a total of 140 independent radio flux-density measurements, with data at more than two frequencies for more than 54% of the sources extending below 500 MHz, enabling the determination of accurate estimates of LR. We find that LR in SCC clusters depends strongly on the cluster scale such that more massive clusters harbor more powerful radio AGN. The same trend is observed between LR and the classical mass deposition rate, dot{M}classical in SCC and partly also in WCC clusters, and can be quantified as LR∝ dot{M}classical1.69±0.25. We also perform correlations of the luminosity for the brightest cluster galaxy, LBCG, close to the X-ray peak in all 64 clusters with LR and cluster parameters, such as the virial mass, M{500}, and the bolometric X-ray luminosity, LX. To this end, we use the 2MASS K-band magnitudes and

  17. The X-ray luminosity-temperature relation of a complete sample of low-mass galaxy clusters

    NASA Astrophysics Data System (ADS)

    Zou, S.; Maughan, B. J.; Giles, P. A.; Vikhlinin, A.; Pacaud, F.; Burenin, R.; Hornstrup, A.

    2016-11-01

    We present Chandra observations of 23 galaxy groups and low-mass galaxy clusters at 0.03 < z < 0.15 with a median temperature of {˜ }2{keV}. The sample is a statistically complete flux-limited subset of the 400 deg2 survey. We investigated the scaling relation between X-ray luminosity (L) and temperature (T), taking selection biases fully into account. The logarithmic slope of the bolometric L-T relation was found to be 3.29 ± 0.33, consistent with values typically found for samples of more massive clusters. In combination with other recent studies of the L-T relation, we show that there is no evidence for the slope, normalization, or scatter of the L-T relation of galaxy groups being different than that of massive clusters. The exception to this is that in the special case of the most relaxed systems, the slope of the core-excised L-T relation appears to steepen from the self-similar value found for massive clusters to a steeper slope for the lower mass sample studied here. Thanks to our rigorous treatment of selection biases, these measurements provide a robust reference against which to compare predictions of models of the impact of feedback on the X-ray properties of galaxy groups.

  18. Spectroscopic pilot study in the near infrared of a sample of star-forming galaxies at z = 2

    NASA Astrophysics Data System (ADS)

    Gallego, J.; Sánchez de Miguel, A.; Zamorano, J.; Pérez-González, P. G.; Cardiel, N.; Barro, G.

    2011-11-01

    In this work we present the results of the spectroscopic analysis inthe near-infrared K band of a sample of 12 active star forminggalaxies at z ˜ 2. The sample was selected by using photometricredshifts, blue colors and large fluxes in the 24 μ m band ofMIPS/Spitzer. To analyze their physical properties we have computedtheir sizes, colors, stellar masses, extinctions and other parametersavailable in literature and in the "Rainbow" database. We computeHα luminosities and star formation rates for all galaxies atthat redshift. We were able to estimate metallicities from [NII]6584for a sub sample of the objects. In particular the dependence of the metallicitywith the stellar mass has been studied and compared with the results of other samples ofgalaxies at several redshifts. For a fixed mass, the metallicities ofour galaxies are compatible than those similar at the corresponding redshift, following the general trend of lower metallicities for higher redshifts.

  19. The SL2S galaxy-scale lens sample. V. dark matter halos and stellar IMF of massive early-type galaxies out to redshift 0.8

    SciTech Connect

    Sonnenfeld, Alessandro; Treu, Tommaso; Marshall, Philip J.; Suyu, Sherry H.; Gavazzi, Raphaël; Auger, Matthew W.; Nipoti, Carlo

    2015-02-17

    Here, we investigate the cosmic evolution of the internal structure of massive early-type galaxies over half of the age of the universe. We also perform a joint lensing and stellar dynamics analysis of a sample of 81 strong lenses from the Strong Lensing Legacy Survey and Sloan ACS Lens Survey and combine the results with a hierarchical Bayesian inference method to measure the distribution of dark matter mass and stellar initial mass function (IMF) across the population of massive early-type galaxies. Lensing selection effects are taken into account. Furthermore, we found that the dark matter mass projected within the inner 5 kpc increases for increasing redshift, decreases for increasing stellar mass density, but is roughly constant along the evolutionary tracks of early-type galaxies. The average dark matter slope is consistent with that of a Navarro-Frenk-White profile, but is not well constrained. The stellar IMF normalization is close to a Salpeter IMF at log M * = 11.5 and scales strongly with increasing stellar mass. No dependence of the IMF on redshift or stellar mass density is detected. The anti-correlation between dark matter mass and stellar mass density supports the idea of mergers being more frequent in more massive dark matter halos.

  20. The SL2S galaxy-scale lens sample. V. dark matter halos and stellar IMF of massive early-type galaxies out to redshift 0.8

    DOE PAGES

    Sonnenfeld, Alessandro; Treu, Tommaso; Marshall, Philip J.; ...

    2015-02-17

    Here, we investigate the cosmic evolution of the internal structure of massive early-type galaxies over half of the age of the universe. We also perform a joint lensing and stellar dynamics analysis of a sample of 81 strong lenses from the Strong Lensing Legacy Survey and Sloan ACS Lens Survey and combine the results with a hierarchical Bayesian inference method to measure the distribution of dark matter mass and stellar initial mass function (IMF) across the population of massive early-type galaxies. Lensing selection effects are taken into account. Furthermore, we found that the dark matter mass projected within the innermore » 5 kpc increases for increasing redshift, decreases for increasing stellar mass density, but is roughly constant along the evolutionary tracks of early-type galaxies. The average dark matter slope is consistent with that of a Navarro-Frenk-White profile, but is not well constrained. The stellar IMF normalization is close to a Salpeter IMF at log M * = 11.5 and scales strongly with increasing stellar mass. No dependence of the IMF on redshift or stellar mass density is detected. The anti-correlation between dark matter mass and stellar mass density supports the idea of mergers being more frequent in more massive dark matter halos.« less

  1. THE SL2S GALAXY-SCALE LENS SAMPLE. V. DARK MATTER HALOS AND STELLAR IMF OF MASSIVE EARLY-TYPE GALAXIES OUT TO REDSHIFT 0.8

    SciTech Connect

    Sonnenfeld, Alessandro; Treu, Tommaso; Marshall, Philip J.; Suyu, Sherry H.; Gavazzi, Raphaël; Auger, Matthew W.; Nipoti, Carlo

    2015-02-20

    We investigate the cosmic evolution of the internal structure of massive early-type galaxies over half of the age of the universe. We perform a joint lensing and stellar dynamics analysis of a sample of 81 strong lenses from the Strong Lensing Legacy Survey and Sloan ACS Lens Survey and combine the results with a hierarchical Bayesian inference method to measure the distribution of dark matter mass and stellar initial mass function (IMF) across the population of massive early-type galaxies. Lensing selection effects are taken into account. We find that the dark matter mass projected within the inner 5 kpc increases for increasing redshift, decreases for increasing stellar mass density, but is roughly constant along the evolutionary tracks of early-type galaxies. The average dark matter slope is consistent with that of a Navarro-Frenk-White profile, but is not well constrained. The stellar IMF normalization is close to a Salpeter IMF at log M {sub *} = 11.5 and scales strongly with increasing stellar mass. No dependence of the IMF on redshift or stellar mass density is detected. The anti-correlation between dark matter mass and stellar mass density supports the idea of mergers being more frequent in more massive dark matter halos.

  2. The SL2S Galaxy-scale Lens Sample. V. Dark Matter Halos and Stellar IMF of Massive Early-type Galaxies Out to Redshift 0.8

    NASA Astrophysics Data System (ADS)

    Sonnenfeld, Alessandro; Treu, Tommaso; Marshall, Philip J.; Suyu, Sherry H.; Gavazzi, Raphaël; Auger, Matthew W.; Nipoti, Carlo

    2015-02-01

    We investigate the cosmic evolution of the internal structure of massive early-type galaxies over half of the age of the universe. We perform a joint lensing and stellar dynamics analysis of a sample of 81 strong lenses from the Strong Lensing Legacy Survey and Sloan ACS Lens Survey and combine the results with a hierarchical Bayesian inference method to measure the distribution of dark matter mass and stellar initial mass function (IMF) across the population of massive early-type galaxies. Lensing selection effects are taken into account. We find that the dark matter mass projected within the inner 5 kpc increases for increasing redshift, decreases for increasing stellar mass density, but is roughly constant along the evolutionary tracks of early-type galaxies. The average dark matter slope is consistent with that of a Navarro-Frenk-White profile, but is not well constrained. The stellar IMF normalization is close to a Salpeter IMF at log M * = 11.5 and scales strongly with increasing stellar mass. No dependence of the IMF on redshift or stellar mass density is detected. The anti-correlation between dark matter mass and stellar mass density supports the idea of mergers being more frequent in more massive dark matter halos.

  3. The star formation rate density of the local universe from an HI-selected sample of galaxies

    NASA Astrophysics Data System (ADS)

    Hanish, Daniel Jeffrey

    We derive observed Ha and R -band luminosity densities of an HI-selected sample of nearby galaxies using the SINGG sample to be [Special characters omitted.] = (8.6 ± 0.9) × 10^38 h 70 ergs s -1 Mpc -3 for Ha and [Special characters omitted.] = (4.3 ± 0.5) x 10 37 h 70 erg s -1 -1 Mpc -3 in the R band. This R -band luminosity density is approximately 70% of that found by the Sloan Digital Sky Survey. This leads to a local star formation rate density of log( [Special characters omitted.] [[Special characters omitted.] yr -1 Mpc -3 ]) = -1.81 [Special characters omitted.] ( random ) ± 0.03( systematic ) + log ( h 70 ) after applying a mean internal extinction correction of 0.87 mag. The gas cycling time of this sample is found to be t gas = 7.3 [Special characters omitted.] Gyr, and the volume-averaged equivalent width of the SINGG galaxies is EW (Ha) = 28.5 [Special characters omitted.] ° (20.0 ± 1.6 ° without internal dust correction). As with similar surveys, these results imply that [Special characters omitted.] ( z ) decreases drastically from z ~ 1.5 to the present. A comparison of the dynamical masses of the SINGG galaxies evaluated at their optical limits with their stellar and HI masses shows significant evidence of downsizing: the most massive galaxies have a larger fraction of their mass locked up in stars compared with H I, while the opposite is true for less massive galaxies. We show that the application of the Kennicutt star formation law to a galaxy having the median orbital time at the optical limit of this sample results in a star formation rate decay with cosmic time simi lar to that given by the [Special characters omitted.] ( z ) evolution. This implies that the [Special characters omitted.] ( z ) evolution is primarily due to the secular evolution of galaxies, rather than interactions or mergers. This is consistent with the morphologies predominantly seen in the SINGG sample.

  4. H I CONTENT AND OPTICAL PROPERTIES OF FIELD GALAXIES FROM THE ALFALFA SURVEY. I. SELECTION OF A CONTROL SAMPLE

    SciTech Connect

    Toribio, M. Carmen; Solanes, Jose M.; Giovanelli, Riccardo; Haynes, Martha P.; Masters, Karen L. E-mail: jm.solanes@ub.edu E-mail: haynes@astro.cornell.edu

    2011-05-10

    We report results from a study of the H I content and stellar properties of nearby galaxies detected by the Arecibo Legacy Fast ALFA blind 21 cm line survey and the Sloan Digital Sky Survey. We consider two declination strips covering a total area of 9 hr x 16 deg in the general direction of the Virgo Cluster. The present analysis focuses on gas-rich galaxies expected to show little or no evidence of interaction with their surroundings. We seek to assemble a control sample suitable for providing absolute measures of the H I content of gaseous objects, as well as to study the relationship between H I emission and widely used optical measures of morphology. From a database which includes more than 15,000 H I detections, we have assembled three samples that could provide adequate H I standards. The most reliable results are obtained with a sample of 5647 sources found in low-density environments, as defined by a nearest neighbor approach. The other two samples contain several hundred relatively isolated galaxies each, as determined from standard isolation algorithms based either on a combination of spectroscopic and photometric information or solely on photometric data. We find that isolated objects are not particularly gas-rich compared to their low-density-environment counterparts, while they suffer from selection bias and span a smaller dynamic range. All this makes them less suitable for defining a reference for H I content. We have explored the optical morphology of gaseous galaxies in quiet environments, finding that, within the volume surveyed, the vast majority of them display unequivocal late-type galaxy features. In contrast, bona fide gas-rich early-type systems account only for a negligible fraction of the 21 cm detections. We argue that H I emission provides the most reliable way to determine the morphological population to which a galaxy belongs. We have also observed that the color distribution of flux-limited samples of optically selected field H I

  5. A multiparametric analysis of the Einstein sample of early-type galaxies. 2: Galaxy formation history and properties of the interstellar medium

    NASA Technical Reports Server (NTRS)

    Eskridge, Paul B.; Fabbiano, Giuseppina; Kim, Dong-Woo

    1995-01-01

    We have conducted bivariate and multivariate statistical analysis of data measuring the integrated luminosity, shape, and potential depth of the Einstein sample of early-type galaxies (presented by Fabbiano et al. 1992). We find significant correlations between the X-ray properties and the axial ratios (a/b) of our sample, such that the roundest systems tend to have the highest L(sub x) and L(sub x)/L(sub B). The most radio-loud objects are also the roundest. We confirm the assertion of Bender et al. (1989) that galaxies with high L(sub x) are boxy (have negative a(sub 4)). Both a/b and a(sub 4) are correlated with L(sub B), but not with IRAS 12 um and 100 um luminosities. There are strong correlations between L(sub x), Mg(sub 2), and sigma(sub nu) in the sense that those systems with the deepest potential wells have the highest L(sub x) and Mg(sub 2). Thus the depth of the potential well appears to govern both the ability to reatin an ISM at the present epoch and to retain the enriched ejecta of early star formation bursts. Both L(sub x)/L(sub B) and L(sub 6) (the 6 cm radio luminosity) show threshold effects with sigma(sub nu) exhibiting sharp increases at log sigma(sub nu) approximately = 2.2. Finally, there is clearly an interrelationship between the various stellar and structural parameters: The scatter in the bivariate relationships between the shape parameters (a/b and a(sub 4)) and the depth parameter sigma(sub nu) is a function of abundance in the sense that, for a given a(sub 4) or a/b, the systems with the highest sigma(sub nu) also have the highest Mg(sub 2). Furthermore, for a constant sigma(sun nu), disky galaxies tend to have higher Mg(sub 2) than boxy ones. Alternatively, for a given abundance, boxy ellipticals tend to be more massive than disky ellipticals. One possibility is that early-type galaxies of a given mass, originating from mergers (boxy ellipticals), have lower abundances than 'primordial' (disky) early-type galaxies. Another is that

  6. A multiparametric analysis of the Einstein sample of early-type galaxies. 2: Galaxy formation history and properties of the interstellar medium

    NASA Technical Reports Server (NTRS)

    Eskridge, Paul B.; Fabbiano, Giuseppina; Kim, Dong-Woo

    1995-01-01

    We have conducted bivariate and multivariate statistical analysis of data measuring the integrated luminosity, shape, and potential depth of the Einstein sample of early-type galaxies (presented by Fabbiano et al. 1992). We find significant correlations between the X-ray properties and the axial ratios (a/b) of our sample, such that the roundest systems tend to have the highest L(sub x) and L(sub x)/L(sub B). The most radio-loud objects are also the roundest. We confirm the assertion of Bender et al. (1989) that galaxies with high L(sub x) are boxy (have negative a(sub 4)). Both a/b and a(sub 4) are correlated with L(sub B), but not with IRAS 12 um and 100 um luminosities. There are strong correlations between L(sub x), Mg(sub 2), and sigma(sub nu) in the sense that those systems with the deepest potential wells have the highest L(sub x) and Mg(sub 2). Thus the depth of the potential well appears to govern both the ability to reatin an ISM at the present epoch and to retain the enriched ejecta of early star formation bursts. Both L(sub x)/L(sub B) and L(sub 6) (the 6 cm radio luminosity) show threshold effects with sigma(sub nu) exhibiting sharp increases at log sigma(sub nu) approximately = 2.2. Finally, there is clearly an interrelationship between the various stellar and structural parameters: The scatter in the bivariate relationships between the shape parameters (a/b and a(sub 4)) and the depth parameter sigma(sub nu) is a function of abundance in the sense that, for a given a(sub 4) or a/b, the systems with the highest sigma(sub nu) also have the highest Mg(sub 2). Furthermore, for a constant sigma(sun nu), disky galaxies tend to have higher Mg(sub 2) than boxy ones. Alternatively, for a given abundance, boxy ellipticals tend to be more massive than disky ellipticals. One possibility is that early-type galaxies of a given mass, originating from mergers (boxy ellipticals), have lower abundances than 'primordial' (disky) early-type galaxies. Another is that

  7. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: baryon acoustic oscillations in the Data Releases 10 and 11 Galaxy samples

    NASA Astrophysics Data System (ADS)

    Anderson, Lauren; Aubourg, Éric; Bailey, Stephen; Beutler, Florian; Bhardwaj, Vaishali; Blanton, Michael; Bolton, Adam S.; Brinkmann, J.; Brownstein, Joel R.; Burden, Angela; Chuang, Chia-Hsun; Cuesta, Antonio J.; Dawson, Kyle S.; Eisenstein, Daniel J.; Escoffier, Stephanie; Gunn, James E.; Guo, Hong; Ho, Shirley; Honscheid, Klaus; Howlett, Cullan; Kirkby, David; Lupton, Robert H.; Manera, Marc; Maraston, Claudia; McBride, Cameron K.; Mena, Olga; Montesano, Francesco; Nichol, Robert C.; Nuza, Sebastián E.; Olmstead, Matthew D.; Padmanabhan, Nikhil; Palanque-Delabrouille, Nathalie; Parejko, John; Percival, Will J.; Petitjean, Patrick; Prada, Francisco; Price-Whelan, Adrian M.; Reid, Beth; Roe, Natalie A.; Ross, Ashley J.; Ross, Nicholas P.; Sabiu, Cristiano G.; Saito, Shun; Samushia, Lado; Sánchez, Ariel G.; Schlegel, David J.; Schneider, Donald P.; Scoccola, Claudia G.; Seo, Hee-Jong; Skibba, Ramin A.; Strauss, Michael A.; Swanson, Molly E. C.; Thomas, Daniel; Tinker, Jeremy L.; Tojeiro, Rita; Magaña, Mariana Vargas; Verde, Licia; Wake, David A.; Weaver, Benjamin A.; Weinberg, David H.; White, Martin; Xu, Xiaoying; Yèche, Christophe; Zehavi, Idit; Zhao, Gong-Bo

    2014-06-01

    We present a one per cent measurement of the cosmic distance scale from the detections of the baryon acoustic oscillations (BAO) in the clustering of galaxies from the Baryon Oscillation Spectroscopic Survey, which is part of the Sloan Digital Sky Survey III. Our results come from the Data Release 11 (DR11) sample, containing nearly one million galaxies and covering approximately 8500 square degrees and the redshift range 0.2 < z < 0.7. We also compare these results with those from the publicly released DR9 and DR10 samples. Assuming a concordance Λ cold dark matter (ΛCDM) cosmological model, the DR11 sample covers a volume of 13 Gpc3 and is the largest region of the Universe ever surveyed at this density. We measure the correlation function and power spectrum, including density-field reconstruction of the BAO feature. The acoustic features are detected at a significance of over 7σ in both the correlation function and power spectrum. Fitting for the position of the acoustic features measures the distance relative to the sound horizon at the drag epoch, rd, which has a value of rd,fid = 149.28 Mpc in our fiducial cosmology. We find DV = (1264 ± 25 Mpc)(rd/rd,fid) at z = 0.32 and DV = (2056 ± 20 Mpc)(rd/rd,fid) at z = 0.57. At 1.0 per cent, this latter measure is the most precise distance constraint ever obtained from a galaxy survey. Separating the clustering along and transverse to the line of sight yields measurements at z = 0.57 of DA = (1421 ± 20 Mpc)(rd/rd,fid) and H = (96.8 ± 3.4 km s-1 Mpc-1)(rd,fid/rd). Our measurements of the distance scale are in good agreement with previous BAO measurements and with the predictions from cosmic microwave background data for a spatially flat CDM model with a cosmological constant.

  8. A Principle Component Analysis of Galaxy Properties from a Large, Gas-Selected Sample

    DOE PAGES

    Chang, Yu-Yen; Chao, Rikon; Wang, Wei-Hao; ...

    2012-01-01

    Disney emore » t al. (2008) have found a striking correlation among global parameters of H i -selected galaxies and concluded that this is in conflict with the CDM model. Considering the importance of the issue, we reinvestigate the problem using the principal component analysis on a fivefold larger sample and additional near-infrared data. We use databases from the Arecibo Legacy Fast Arecibo L -band Feed Array Survey for the gas properties, the Sloan Digital Sky Survey for the optical properties, and the Two Micron All Sky Survey for the near-infrared properties. We confirm that the parameters are indeed correlated where a single physical parameter can explain 83% of the variations. When color ( g - i ) is included, the first component still dominates but it develops a second principal component. In addition, the near-infrared color ( i - J ) shows an obvious second principal component that might provide evidence of the complex old star formation. Based on our data, we suggest that it is premature to pronounce the failure of the CDM model and it motivates more theoretical work.« less

  9. The Dust Content and Radiation Fields of Sample of Galaxies in the ELAIS-N1 Field

    NASA Astrophysics Data System (ADS)

    Shalima, P.; Gogoi, Rupjyoti; Pathak, Amit; Misra, Ranjeev; Gupta, Ranjan; Vaidya, D. B.

    2015-08-01

    The Mid-IR colors ($F_{8}/F_{24}$) of galaxies together with their IR-UV luminosity correlations can be used to get some insight into the relative abundance of the different dust grain populations present in them. The ELAIS-N1 field contains thousands of galaxies which do not have optical spectra but have been observed in the Mid-IR by {\\it Spitzer} and UV by {\\it GALEX} making it ideal for these studies. As part of this work we have selected a sample of galaxies from the ELAIS-N1 field which have photometric observations in the MIR and UV as well as photometric redshifts from the SDSS database. We put the constraint that the redshifts are $\\le$ 0.1, thereby giving us a total of 309 galaxies. We find that the majority of the galaxies in the sample are PAH dominated due to their high MIR flux ratio. We also find a reasonable correlation between the Mid-IR and the UV luminosities out of which the Mid-IR emission from PAHs at 8 $\\mu$m is marginally better correlated than the 24 $\\mu$m VSG emission with the UV luminosities. However, if we divide the sample based on their $F_{8}/F_{24}$ ratios which is also an indicator of metallicity, the MIR-UV correlation seems to increase with the $F_{8}/F_{24}$ ratio. But the MIR-UV correlations are not very different for the PAHs and the VSG population within the individual metallicity groups.

  10. The FUV to Near-IR Morphologies of Luminous Infrared Galaxies in the Goals Sample

    NASA Astrophysics Data System (ADS)

    Petty, S. M.; Armus, L.; Charmandaris, V.; Evans, A. S.; Le Floc'h, E.; Bridge, C.; Díaz-Santos, T.; Howell, J. H.; Inami, H.; Psychogyios, A.; Stierwalt, S.; Surace, J. A.

    2014-12-01

    We compare the morphologies of a sample of 20 luminous infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey (GOALS) in the FUV, B, I, and H bands, using the Gini (G) and M20 parameters to quantitatively estimate the distribution and concentration of flux as a function of wavelength. Hubble Space Telescope (HST) images provide an average spatial resolution of ˜ 80 pc. While our LIRGs can be reliably classified as mergers across the entire range of wavelengths studied here, there is a clear shift toward more negative M20 (more bulge-dominated) and a less significant decrease in G values at longer wavelengths. We find no correlation between the derived FUV G-M20 parameters and the global measures of the IR to FUV flux ratio (IRX). Given the fine resolution in our HST data, this suggests either that the UV morphology and IRX are correlated on very small scales, or that the regions emitting the bulk of the IR emission emit almost no FUV light. We use our multi-wavelength data to simulate how merging LIRGs would appear from z˜ 0.5-3 in deep optical and near-infrared images such as the Hubble Ultra-Deep Field, and use these simulations to measure the G-M20 at these redshifts. Our simulations indicate a noticeable decrease in G, which flattens at z≥slant 2 by as much as 40%, resulting in mis-classifying our LIRGs as disk-like, even in the rest-frame FUV. The higher redshift values of M20 for the GOALS sources do not appear to change more than about 10% from the values at z˜ 0. The change in G-M20 is caused by the surface brightness dimming of extended tidal features and asymmetries, and also the decreased spatial resolution which reduced the number of individual clumps identified. This effect, seen as early as z˜ 0.5, could easily lead to an underestimate of the number of merging galaxies at high-redshift in the rest-frame FUV.

  11. The FUR to near-IR morphologies of luminous infrared galaxies in the goals sample

    SciTech Connect

    Petty, S. M.; Armus, L.; Díaz-Santos, T.; Howell, J. H.; Surace, J. A.; Charmandaris, V.; Psychogyios, A.; Evans, A. S.; Stierwalt, S.; Floc’h, E. Le; Bridge, C.; Inami, H.

    2014-12-01

    We compare the morphologies of a sample of 20 luminous infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey (GOALS) in the FUV, B, I, and H bands, using the Gini (G) and M{sub 20} parameters to quantitatively estimate the distribution and concentration of flux as a function of wavelength. Hubble Space Telescope (HST) images provide an average spatial resolution of ∼80 pc. While our LIRGs can be reliably classified as mergers across the entire range of wavelengths studied here, there is a clear shift toward more negative M{sub 20} (more bulge-dominated) and a less significant decrease in G values at longer wavelengths. We find no correlation between the derived FUV G-M{sub 20} parameters and the global measures of the IR to FUV flux ratio (IRX). Given the fine resolution in our HST data, this suggests either that the UV morphology and IRX are correlated on very small scales, or that the regions emitting the bulk of the IR emission emit almost no FUV light. We use our multi-wavelength data to simulate how merging LIRGs would appear from z∼0.5–3 in deep optical and near-infrared images such as the Hubble Ultra-Deep Field, and use these simulations to measure the G-M{sub 20} at these redshifts. Our simulations indicate a noticeable decrease in G, which flattens at z⩾2 by as much as 40%, resulting in mis-classifying our LIRGs as disk-like, even in the rest-frame FUV. The higher redshift values of M{sub 20} for the GOALS sources do not appear to change more than about 10% from the values at z∼0. The change in G-M{sub 20} is caused by the surface brightness dimming of extended tidal features and asymmetries, and also the decreased spatial resolution which reduced the number of individual clumps identified. This effect, seen as early as z∼0.5, could easily lead to an underestimate of the number of merging galaxies at high-redshift in the rest-frame FUV.

  12. Mg II Absorption Characteristics of a Volume-Limited Sample of Galaxies at z ~ 0.1

    NASA Astrophysics Data System (ADS)

    Barton, Elizabeth J.; Cooke, Jeff

    2009-12-01

    We present an initial survey of Mg II absorption characteristics in the halos of a carefully constructed, volume-limited subsample of galaxies embedded in the spectroscopic part of the Sloan Digital Sky Survey (SDSS). We observed quasars near sightlines to 20 low-redshift (z ~ 0.1), luminous (M r + 5log h <=-20.5) galaxies in SDSS DR4 and DR6 with the LRIS-B spectrograph on the Keck I telescope. The primary systematic criteria for the targeted galaxies are a redshift z gsim 0.1 and the presence of an appropriate bright background quasar within a projected 75 h -1 kpc of its center, although we preferentially sample galaxies with lower impact parameters and slightly more star formation within this range. Of the observed systems, six exhibit strong (W eq(2796) >= 0.3 Å) Mg II absorption at the galaxy's redshift, six systems have upper limits which preclude strong Mg II absorption, while the remaining observations rule out very strong (W eq(2796) >= 1-2 Å) absorption. The absorbers fall at higher impact parameters than many non-absorber sightlines, indicating a covering fraction fc lsim 0.4 for >=0.3 Å absorbers at z ~ 0.1, even at impact parameters <=35 h -1 kpc (f c ~ 0.25). The data are consistent with a possible dependence of covering fraction and/or absorption halo size on the environment or star-forming properties of the central galaxy. 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.

  13. Mg II ABSORPTION CHARACTERISTICS OF A VOLUME-LIMITED SAMPLE OF GALAXIES AT z {approx} 0.1

    SciTech Connect

    Barton, Elizabeth J.; Cooke, Jeff E-mail: cooke@uci.edu

    2009-12-15

    We present an initial survey of Mg II absorption characteristics in the halos of a carefully constructed, volume-limited subsample of galaxies embedded in the spectroscopic part of the Sloan Digital Sky Survey (SDSS). We observed quasars near sightlines to 20 low-redshift (z {approx} 0.1), luminous (M {sub r} + 5log h {<=}-20.5) galaxies in SDSS DR4 and DR6 with the LRIS-B spectrograph on the Keck I telescope. The primary systematic criteria for the targeted galaxies are a redshift z {approx}> 0.1 and the presence of an appropriate bright background quasar within a projected 75 h {sup -1} kpc of its center, although we preferentially sample galaxies with lower impact parameters and slightly more star formation within this range. Of the observed systems, six exhibit strong (W {sub eq}(2796) {>=} 0.3 A) Mg II absorption at the galaxy's redshift, six systems have upper limits which preclude strong Mg II absorption, while the remaining observations rule out very strong (W {sub eq}(2796) {>=} 1-2 A) absorption. The absorbers fall at higher impact parameters than many non-absorber sightlines, indicating a covering fraction f{sub c} {approx}< 0.4 for {>=}0.3 A absorbers at z {approx} 0.1, even at impact parameters {<=}35 h {sup -1} kpc (f {sub c} {approx} 0.25). The data are consistent with a possible dependence of covering fraction and/or absorption halo size on the environment or star-forming properties of the central galaxy.

  14. Deep WFPC2 and Ground-Based Imaging of a Complete Sample of 3C Quasars and Galaxies

    NASA Technical Reports Server (NTRS)

    Ridgway, Susan E.; Stockton, Alan

    1997-01-01

    We present the results of an HST and ground-based imaging study of a complete 3C sample of zeta approx. equal to 1 sources, comprising 5 quasars and 5 radio galaxies. We have observed all of the sample in essentially line-free bands at rest-frame 0.33 micrometers with WFPC2 and in rest-frame 1 micrometer images from the ground; we have also observed most of the sample in narrow-band filters centered on [O II]. We resolve continuum structure around all of our quasars in the high-resolution WFPC2 images, and in four of the five ground-based K' images. All of the quasars have some optical continuum structure that is aligned with the radio axis. In at least 3 of these cases, some of this optical structure is directly coincident with a portion of the radio structure, including optical counterparts to radio jets in 3C212 and 3C245 and an optical counterpart to a radio lobe in 3C2. These are most likely due to optical synchrotron radiation, and the radio and optical spectral indices in the northern lobe of 3C2 are consistent with this interpretation. The fact that we see a beamed optical synchotron component in the quasars but not in the radio galaxies complicates both the magnitude and the alignment comparisons. Nonetheless, the total optical and K' flux densities of the quasar hosts are consistent with those of the radio galaxies within the observed dispersion in our sample. The distributions of K' flux densities of both radio galaxies and quasar hosts exhibit similar mean and dispersion to that found for other radio galaxies at this redshift, and the average host galaxy luminosity is equivalent to, or a little fainter than, L*. The formal determination of the alignment in the optical and infrared in the two subsamples yields no significant difference between the radio galaxy and quasar subsamples, and the quasars 3C 196 and 3C 336 have aligned continuum and emission-line structure that is probably not due to beamed optical synchrotron emission. Very blue and/or edge

  15. A multiparametric analysis of the Einstein sample of early-type galaxies. 1: Luminosity and ISM parameters

    NASA Technical Reports Server (NTRS)

    Eskridge, Paul B.; Fabbiano, Giuseppina; Kim, Dong-Woo

    1995-01-01

    We have conducted bivariate and multivariate statistical analysis of data measuring the luminosity and interstellar medium of the Einstein sample of early-type galaxies (presented by Fabbiano, Kim, & Trinchieri 1992). We find a strong nonlinear correlation between L(sub B) and L(sub X), with a power-law slope of 1.8 +/- 0.1, steepening to 2.0 +/- if we do not consider the Local Group dwarf galaxies M32 and NGC 205. Considering only galaxies with log L(sub X) less than or equal to 40.5, we instead find a slope of 1.0 +/- 0.2 (with or without the Local Group dwarfs). Although E and S0 galaxies have consistent slopes for their L(sub B)-L(sub X) relationships, the mean values of the distribution functions of both L(sub X) and L(sub X)/L(sub B) for the S0 galaxies are lower than those for the E galaxies at the 2.8 sigma and 3.5 sigma levels, respectively. We find clear evidence for a correlation between L(sub X) and the X-ray color C(sub 21), defined by Kim, Fabbiano, & Trinchieri (1992b), which indicates that X-ray luminosity is correlated with the spectral shape below 1 keV in the sense that low-L(sub X) systems have relatively large contributions from a soft component compared with high-L(sub X) systems. We find evidence from our analysis of the 12 micron IRAS data for our sample that our S0 sample has excess 12 micron emission compared with the E sample, scaled by their optical luminosities. This may be due to emission from dust heated in star-forming regions in S0 disks. This interpretation is reinforced by the existence of a strong L(sub 12)-L(sub 100) correlation for our S0 sample that is not found for the E galaxies, and by an analysis of optical-IR colors. We find steep slopes for power-law relationships between radio luminosity and optical, X-ray, and far-IR (FIR) properties. This last point argues that the presence of an FIR-emitting interstellar medium (ISM) in early-type galaxies is coupled to their ability to generate nonthermal radio continuum, as

  16. C II 158 ??bservations of a Sample of Late-type Galaxies from the Virgo Cluster

    NASA Technical Reports Server (NTRS)

    Leech, K.; Volk, H.; Heinrichsen, I.; Hippelein, H.; Metcalfe, L.; Pierini, D.; Popescu, C.; Tuffs, R.; Xu, C.

    1999-01-01

    We have observed 19 Virgo cluster spiral galaxies with the Long Wavelength Spectrometer (LWS) onboard ESAs Infrared Space Observatory (ISO) obtaining spectra around the [CII] 157.741 ??ine structure line.

  17. Study of a homogeneous QSO sample: relations between the QSO and its host galaxy

    NASA Astrophysics Data System (ADS)

    Letawe, Y.; Letawe, G.; Magain, P.

    2010-04-01

    We analyse a sample of 69 quasi-stellar objects (QSOs) which have been randomly selected in a complete sample of 104 QSOs (R <= 18,0.142 < z < 0.198,δ < 10°). 60 have been observed with the NTT/SUSI2 at La Silla, through two filters in the optical band (WB 655 and V 812), and the remaining nine are taken from archive data bases. The filter V 812 contains the redshifted Hβ and forbidden [OIII] emission lines, while WB 655 covers a spectral region devoid of emission lines, thus measuring the QSO and stellar continua. The contributions of the QSO and the host are separated thanks to the MCS deconvolution algorithm, allowing a morphological classification of the host, and the computation of several parameters such as the host and nucleus absolute V magnitude, distance between the luminosity centre of the host and the QSO and colour of the host and nucleus. We define a new asymmetry coefficient, independent of any galaxy models and well suited for QSO host studies. The main results from this study are (i) 25 per cent of the total number of QSO hosts are spirals, 51 per cent are ellipticals and 60 per cent show signs of interaction, (ii) highly asymmetric systems tend to have a higher gas ionization level and (iii) elliptical hosts contain a substantial amount of ionized gas and some show off-nuclear activity. These results agree with hierarchical models merger driven evolution. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under programme IDs 77.B-0229 and 78.B-0081. E-mail: gletawe@ulg.ac.be

  18. INFRARED SPECTRAL ENERGY DISTRIBUTIONS OF SEYFERT GALAXIES: SPITZER SPACE TELESCOPE OBSERVATIONS OF THE 12 {mu}m SAMPLE OF ACTIVE GALAXIES

    SciTech Connect

    Gallimore, J. F.; Yzaguirre, A.; Jakoboski, J.; Stevenosky, M. J.; Axon, D. J.; O'Dea, C. P.; Robinson, A.; Baum, S. A.; Buchanan, C. L.; Elitzur, M.; Elvis, M.

    2010-03-01

    The mid-infrared spectral energy distributions (SEDs) of 83 active galaxies, mostly Seyfert galaxies, selected from the extended 12 {mu}m sample are presented. The data were collected using all three instruments, Infrared Array Camera (IRAC), Infrared Spectrograph (IRS), and Multiband Imaging Photometer for Spitzer (MIPS), aboard the Spitzer Space Telescope. The IRS data were obtained in spectral mapping mode, and the photometric data from IRAC and IRS were extracted from matched, 20'' diameter circular apertures. The MIPS data were obtained in SED mode, providing very low-resolution spectroscopy (R {approx} 20) between {approx}55 and 90 {mu}m in a larger, 20'' x 30'' synthetic aperture. We further present the data from a spectral decomposition of the SEDs, including equivalent widths and fluxes of key emission lines; silicate 10 {mu}m and 18 {mu}m emission and absorption strengths; IRAC magnitudes; and mid-far-infrared spectral indices. Finally, we examine the SEDs averaged within optical classifications of activity. We find that the infrared SEDs of Seyfert 1s and Seyfert 2s with hidden broad line regions (HBLRs, as revealed by spectropolarimetry or other technique) are qualitatively similar, except that Seyfert 1s show silicate emission and HBLR Seyfert 2s show silicate absorption. The infrared SEDs of other classes within the 12 {mu}m sample, including Seyfert 1.8-1.9, non-HBLR Seyfert 2 (not yet shown to hide a type 1 nucleus), LINER, and H II galaxies, appear to be dominated by star formation, as evidenced by blue IRAC colors, strong polycyclic aromatic hydrocarbon emission, and strong far-infrared continuum emission, measured relative to mid-infrared continuum emission.

  19. Redshifts for a sample of fainter galaxies in the first CfA survey slice

    NASA Technical Reports Server (NTRS)

    Thorstensen, J. R.; Wegner, G. A.; Hamwey, R.; Boley, F.; Geller, M. J.

    1989-01-01

    Redshifts were measured for 93 of the 94 galaxies in the Zwicky-Nilson merged catalog with the value of m(B/01) between 15.5 and 15.7 and with right ascension alpha between 8(h) and 17(h) and declination delta between 29 and 30 deg. This region is within the one covered by the first slice of the CfA (Center for Astrophysics) survey. The galaxies reinforce features already visible in the earlier survey.

  20. Precise Strong Lensing Mass Modeling of Four Hubble Frontier Field Clusters and a Sample of Magnified High-redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Kawamata, Ryota; Oguri, Masamune; Ishigaki, Masafumi; Shimasaku, Kazuhiro; Ouchi, Masami

    2016-03-01

    We conduct precise strong lensing mass modeling of four Hubble Frontier Field (HFF) clusters, Abell 2744, MACS J0416.1-2403, MACS J0717.5+3745, and MACS J1149.6+2223, for which HFF imaging observations are completed. We construct a refined sample of more than 100 multiple images for each cluster by taking advantage of the full-depth HFF images, and conduct mass modeling using the glafic software, which assumes simply parametrized mass distributions. Our mass modeling also exploits a magnification constraint from the lensed SN Ia HFF14Tom for Abell 2744 and positional constraints from the multiple images S1-S4 of the lensed supernova SN Refsdal for MACS J1149.6+2223. We find that our best-fitting mass models reproduce the observed image positions with rms errors of ˜0.″4, which are smaller than rms errors in previous mass modeling that adopted similar numbers of multiple images. Our model predicts a new image of SN Refsdal with a relative time delay and magnification that are fully consistent with a recent detection of reappearance. We then construct catalogs of z ˜ 6-9 dropout galaxies behind the four clusters and estimate magnification factors for these dropout galaxies with our best-fitting mass models. The dropout sample from the four cluster fields contains ˜120 galaxies at z ≳ 6, about 20 of which are predicted to be magnified by a factor of more than 10. Some of the high-redshift galaxies detected in the HFF have lensing-corrected magnitudes of MUV ˜ -15 to -14. Our analysis demonstrates that the HFF data indeed offer an ideal opportunity to study faint high-redshift galaxies. All lensing maps produced from our mass modeling will be made available on the Space Telescope Science Institute website (https://archive.stsci.edu/prepds/frontier/lensmodels/).

  1. Spectrophotometric study in the near-IR of a sample of H alpha-selected galaxies with active star formation at z = 0.84

    NASA Astrophysics Data System (ADS)

    Sánchez de Miguel, A.; Gallego, J.; Villar, V.; Zamorano, J.; Acosta, J.; Pérez-Gonzalez, P. G.; Barro, G.

    2011-11-01

    In this work we present the results of the spectroscopic analysis in the near-infrared J band of a sample of 48 star forming galaxies at z = 0.84. Half of the sample was selected by a narrow-band filter tuned to Hα at that redshift and the other half was selected by photometric redshifts at the same redshift. We provide Hα luminosities and star formation rates for all galaxies at that redshift. We were able to estimate metallicities from [NII]6584 Å for a sub sample of eight galaxies, two of the galaxies were from neckband selection. To analyze their physical properties we have computed their sizes, colors, stellar masses, extinctions and other parameters available in literature and in the Rainbow database. In particular the dependence of the stellar mass with the specific star formation rate and metallicity have been studied and compared with the results of other samples of galaxies at several redshifts. For a fixed mass, the metallicities of our galaxies are compatible than those similar at the local Universe, although with higher dispersion. This fact implies that selection in Hα is less biased than a selection in UV, since it includes galaxies with more evolved populations besides objects dominated by star formation. The comparison of the observed properties with models of evolution leads us to think that z = 0.8 star-forming galaxies have already undergone significant changes and begin to developed in a more passive way.

  2. Comparing Cool Cores in the Planck SZ Selected Samples of Clusters of Galaxies with Cool Cores in X-ray Selected Cluster Samples

    NASA Astrophysics Data System (ADS)

    Jones, Christine; Santos, Felipe A.; Forman, William R.; Kraft, Ralph P.; Lovisari, Lorenzo; Arnaud, Monique; Mazzotta, Pasquale; Van Weeren, Reinout J.; Churazov, Eugene; Ferrari, Chiara; Borgani, Stefano; Chandra-Planck Collaboration

    2016-06-01

    The Planck mission provided a representative sample of clusters of galaxies over the entire sky. With completed Chandra observations of 165 Planck ESZ and cosmology sample clusters at z<0.35, we can now characterize each cluster in terms of its X-ray luminosity, gas temperature, gas mass, total mass, gas entropy, gas central cooling time, presence of active AGN, gas cavities, radio emission, and cluster morphology. In this presentation we compare the percentages of cool core and non-cool core clusters in the Planck-selected clusters with the percentages in X-ray selected cluster samples. We find a significantly smaller percentage of cool core clusters in the Planck sample than in X-ray selected cluster samples. We will discuss the primary reasons for this smaller percentage of cool-core clusters in the Planck-selected cluster sample than in X-ray-selected samples.

  3. NIHAO project - I. Reproducing the inefficiency of galaxy formation across cosmic time with a large sample of cosmological hydrodynamical simulations

    NASA Astrophysics Data System (ADS)

    Wang, Liang; Dutton, Aaron A.; Stinson, Gregory S.; Macciò, Andrea V.; Penzo, Camilla; Kang, Xi; Keller, Ben W.; Wadsley, James

    2015-11-01

    We introduce project NIHAO (Numerical Investigation of a Hundred Astrophysical Objects), a set of 100 cosmological zoom-in hydrodynamical simulations performed using the GASOLINE code, with an improved implementation of the SPH algorithm. The haloes in our study range from dwarf (M200 ˜ 5 × 109 M⊙) to Milky Way (M200 ˜ 2 × 1012 M⊙) masses, and represent an unbiased sampling of merger histories, concentrations and spin parameters. The particle masses and force softenings are chosen to resolve the mass profile to below 1 per cent of the virial radius at all masses, ensuring that galaxy half-light radii are well resolved. Using the same treatment of star formation and stellar feedback for every object, the simulated galaxies reproduce the observed inefficiency of galaxy formation across cosmic time as expressed through the stellar mass versus halo mass relation, and the star formation rate versus stellar mass relation. We thus conclude that stellar feedback is the chief piece of physics required to limit the efficiency of star formation in galaxies less massive than the Milky Way.

  4. The X-Ray Weakness of GPS Radio Galaxies: A Volume-Limited Complete Sample

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard F. (Technical Monitor); Siemiginowska, Aneta (Principal Investigator)

    2004-01-01

    The XMM observations of Mkn 668 have been analyzed. We found soft X-ray signatures of a hot plasma (kT approximately 10^7 approximately K) and a hard X-ray emission from the nucleus. The X-ray spectrum above 2.5 approximately keV is characterized by a very flat (observed photon index, Gamma approximately 0.5) power-law continuum, alongside with a strong Fe-K-alpha neutral iron fluorescent line (EW approximately 600 approximately eV). The best explanation for the origin of this high energy X-ray emission is in terms of the Compton-reflection of the nuclear emission. The primary X-ray emission is obscured by a Compton-thick (N_H approximately 10^24 approximately cm-2) matter which becomes transparent at higher energies. The observed above 2.5-keV X-rays are mostly due to reflection which is indicated by a strong Fe-K-alpha line. This represents the second hard X-ray detection of the GPS galaxy ever (the first one being 1345+125; O Dea et al. 2000). Interestingly, the both such trend is confirmed by our on going XMM-Newton observations of a larger GPS sample, it would lead us to looking into the question on how the dense nuclear environment impacts the nature and evolution of a GPS source, and more generally, on the history of radio power in the universe. The paper summarizing the results has been submitted to Astronomy and Astrophysics in December 2003.

  5. Cosmic Voids in the SDSS DR12 BOSS Galaxy Sample: The Alcock-Paczynski Test

    NASA Astrophysics Data System (ADS)

    Mao, Qingqing; Berlind, Andreas A.; Scherrer, Robert J.; Neyrinck, Mark C.; Scoccimarro, Román; Tinker, Jeremy L.; McBride, Cameron K.; Schneider, Donald P.

    2017-02-01

    We apply the Alcock–Paczyński (AP) test to stacked voids identified using the final data release (DR12) of the Baryon Oscillation Spectroscopic Survey (BOSS). We also use 1000 mock galaxy catalogs that match the geometry, density, and clustering properties of the BOSS sample in order to characterize the statistical uncertainties of our measurements and take into account systematic errors such as redshift space distortions. For both BOSS data and mock catalogs, we use the ZOBOV algorithm to identify voids, we stack together all voids with effective radii of 30{--}100 {h}-1 {Mpc} in the redshift range of 0.43–0.7, and we accurately measure the shape of the stacked voids. Our tests with the mock catalogs show that we measure the stacked void ellipticity with a statistical precision of 2.6%. The stacked voids in redshift space are slightly squashed along the line of sight, consistent with previous studies. We repeat this measurement of stacked void shape in the BOSS data, assuming several values of {{{Ω }}}{{m}} within the flat {{Λ }}{CDM} model, and we compare this to the mock catalogs in redshift space to perform the AP test. We obtain a constraint of {{{Ω }}}{{m}}={0.38}-0.15+0.18 at the 68% confidence level from the AP test. We discuss the sources of statistical and systematic noise that affect the constraining power of this method. In particular, we find that the measured ellipticity of stacked voids changes more weakly with cosmology than the standard AP prediction, leading to significantly weaker constraints. We discuss how constraints will improve in future surveys with larger volumes and densities.

  6. Joint scaling properties of Sunyaev-Zel'dovich and optical richness observables in an optically-selected galaxy cluster sample

    NASA Astrophysics Data System (ADS)

    Greer, Christopher Holland

    Galaxy cluster abundance measurements are an important tool used to study the universe as a whole. The advent of multiple large-area galaxy cluster surveys across multiple ensures that cluster measurements will play a key role in understanding the dark energy currently thought to be accelerating the universe. The main systematic limitation at the moment is the understanding of the observable-mass relation. Recent theoretical work has shown that combining samples of clusters from surveys at different wavelengths can mitigate this systematic limitation. Precise measurements of the scatter in the observable-mass relation can lead to further improvements. We present Combined Array for Research in Millimeter-wave Astronomy (CARMA) observations of the Sunyaev-Zel'dovich (SZ) signal for 28 galaxy clusters selected from the Sloan Digital Sky Survey (SDSS) maxBCG catalog. This cluster sample represents a complete, volume-limited sample of the richest galaxy clusters in the SDSS between redshifts 0.2 ≥ z ≥ 0.3, as measured by the RedMaPPer algorithm being developed for the Dark Energy Survey (DES; Rykoff et al. 2012). We develop a formalism that uses the cluster abundance in tandem with the galaxy richness measurements from SDSS and the SZ signal measurements from CARMA to calibrate the SZ and optical observable-mass relations. We find that the scatter in richness at fixed mass is σlog λ| M = 0.24+0.09-0.07 using SZ signal calculated by integrating a cluster pressure profile to a radius of 1 Mpc at the redshift of the cluster. We also calculate the SZ signal at R500 and find that the choice of scaling relation used to determined R500 has a non-trivial effect on the constraints of the observable-mass relationship. Finally, we investigate the source of disagreement between the positions of the SZ signal and SDSS Brightest Cluster Galaxies (BCGs). Improvements to the richness calculator that account for blue BCGs in the cores of cool-core X-ray clusters, as well as

  7. Using dust, gas and stellar mass-selected samples to probe dust sources and sinks in low-metallicity galaxies

    NASA Astrophysics Data System (ADS)

    De Vis, P.; Gomez, H. L.; Schofield, S. P.; Maddox, S.; Dunne, L.; Baes, M.; Cigan, P.; Clark, C. J. R.; Gomez, E. L.; Lara-López, M.; Owers, M.

    2017-10-01

    We combine samples of nearby galaxies with Herschel photometry selected on their dust, metal, H I and stellar mass content, and compare these to chemical evolution models in order to discriminate between different dust sources. In a companion paper, we used an H i-selected sample of nearby galaxies to reveal a subsample of very gas-rich (gas fraction >80 per cent) sources with dust masses significantly below predictions from simple chemical evolution models, and well below Md/M* and Md/Mgas scaling relations seen in dust and stellar-selected samples of local galaxies. We use a chemical evolution model to explain these dust-poor, but gas-rich, sources as well as the observed star formation rates (SFRs) and dust-to-gas ratios. We find that (i) a delayed star formation history is required to model the observed SFRs; (ii) inflows and outflows are required to model the observed metallicities at low gas fractions; (iii) a reduced contribution of dust from supernovae (SNe) is needed to explain the dust-poor sources with high gas fractions. These dust-poor, low stellar mass galaxies require a typical core-collapse SN to produce 0.01-0.16 M⊙ of dust. To match the observed dust masses at lower gas fractions, significant grain growth is required to counteract the reduced contribution from dust in SNe and dust destruction from SN shocks. These findings are statistically robust, though due to intrinsic scatter it is not always possible to find one single model that successfully describes all the data. We also show that the dust-to-metal ratio decreases towards lower metallicity.

  8. The BRAVE Program. I. Improved Bulge Stellar Velocity Dispersion Estimates for a Sample of Active Galaxies

    NASA Astrophysics Data System (ADS)

    Batiste, Merida; Bentz, Misty C.; Manne-Nicholas, Emily R.; Onken, Christopher A.; Bershady, Matthew A.

    2017-02-01

    We present new bulge stellar velocity dispersion measurements for 10 active galaxies with secure MBH determinations from reverberation mapping. These new velocity dispersion measurements are based on spatially resolved kinematics from integral-field (IFU) spectroscopy. In all but one case, the field of view of the IFU extends beyond the effective radius of the galaxy, and in the case of Mrk 79 it extends to almost one half the effective radius. This combination of spatial resolution and field of view allows for secure determinations of stellar velocity dispersion within the effective radius for all 10 target galaxies. Spatially resolved maps of the first (V) and second (σ⋆) moments of the line of sight velocity distribution indicate the presence of kinematic substructure in most cases. In future projects we plan to explore methods of correcting for the effects of kinematic substructure in the derived bulge stellar velocity dispersion measurements.

  9. INTRACLUSTER MEDIUM ENTROPY PROFILES FOR A CHANDRA ARCHIVAL SAMPLE OF GALAXY CLUSTERS

    SciTech Connect

    Cavagnolo, Kenneth W.; Donahue, Megan; Voit, G. Mark; Sun Ming

    2009-05-15

    We present radial entropy profiles of the intracluster medium (ICM) for a collection of 239 clusters taken from the Chandra X-ray Observatory's Data Archive. Entropy is of great interest because it controls ICM global properties and records the thermal history of a cluster. Entropy is therefore a useful quantity for studying the effects of feedback on the cluster environment and investigating any breakdown of cluster self-similarity. We find that most ICM entropy profiles are well fitted by a model which is a power law at large radii and approaches a constant value at small radii: K(r) = K {sub 0} + K {sub 100}(r/100 kpc){sup {alpha}}, where K {sub 0} quantifies the typical excess of core entropy above the best-fitting power law found at larger radii. We also show that the K {sub 0} distributions of both the full archival sample and the primary Highest X-Ray Flux Galaxy Cluster Sample of Reiprich (2001) are bimodal with a distinct gap between K {sub 0} {approx} 30-50 keV cm{sup 2} and population peaks at K {sub 0} {approx} 15 keV cm{sup 2} and K {sub 0} {approx} 150 keV cm{sup 2}. The effects of point-spread function smearing and angular resolution on best-fit K {sub 0} values are investigated using mock Chandra observations and degraded entropy profiles, respectively. We find that neither of these effects is sufficient to explain the entropy-profile flattening we measure at small radii. The influence of profile curvature and number of radial bins on best-fit K {sub 0} is also considered, and we find no indication that K {sub 0} is significantly impacted by either. For completeness, we include previously unpublished optical spectroscopy of H{alpha} and [N II] emission lines discussed in Cavagnolo et al. (2008a). All data and results associated with this work are publicly available via the project Web site.

  10. Optical-infrared colors of a complete sample of field galaxies with spectroscopic redshifts.

    NASA Astrophysics Data System (ADS)

    Bershady, M.; Hereld, M.; Kron, R.; Koo, D.

    The authors investigate the optical-infrared color distribution of 135 optically selected field galaxies in the Koo-Kron redshift survey. All objects have UJBFNK photometry with spectroscopic redshifts ranging from 0.018 to 0.35 (a look back time of 4.5 h50-1Gyr, q0 = 0). The distribution in N-K vs z is explored with the aid of the K band luminosity and optical-infrared multi-color distributions. These results provide the basis for future tests of galaxy evolution models of optical and near-infrared light.

  11. VizieR Online Data Catalog: KINGFISH galaxy sample radial profile SED (Hunt+, 2015)

    NASA Astrophysics Data System (ADS)

    Hunt, L. K.; Draine, B. T.; Bianchi, S.; Gordon, K. D.; Aniano, G.; Calzetti, D.; Dale, D. A.; Helou, G.; Hinz, J. L.; Kennicutt, R. C.; Roussel, H.; Wilson, C. D.; Bolatto, A.; Boquien, M.; Croxall, K. V.; Galametz, M.; Gil de Paz, A.; Koda, J.; Munoz-Mateos, J. C.; Sandstrom, K. M.; Sauvage, M.; Vigroux, L.; Zibett, S.

    2014-10-01

    Radial profile spectral energy distributions (SEDs) for the KINGFISH galaxies. The profiles are extracted from the convolved and sky-subtracted images, and all have the same spatial resolution, roughly 39-arcsec. The annular fluxes were extracted along fixed-shape ellipses with radial bins of 18-arcsec. A masking technique was applied to galaxies more inclined than 60°. Uncertainties were calculated as the quadrature sum of calibration uncertainty and the mean error of the standard deviation of the surface brightness distribution along the elliptical isophote circumference. The uncertainties for PACS and MIPS data were adjusted when necessary for discrepancies larger than the nominal uncertainties. (2 data files).

  12. The 2XMMi/SDSS Galaxy Cluster Survey. II. The optically confirmed cluster sample and the LX - T relation

    NASA Astrophysics Data System (ADS)

    Takey, A.; Schwope, A.; Lamer, G.

    2013-10-01

    Aims: We compile a sample of X-ray-selected galaxy groups and clusters from the XMM-Newton serendipitous source catalogue (2XMMi-DR3) with optical confirmation and redshift measurement from the Sloan Digital Sky Survey (SDSS). We present an analysis of the X-ray properties of this new sample with particular emphasis on the X-ray luminosity-temperature (LX - T) relation. Methods: The X-ray cluster candidates were selected from the 2XMMi-DR3 catalogue in the footprint of the SDSS-DR7. We developed a finding algorithm to search for overdensities of galaxies at the positions of the X-ray cluster candidates in the photometric redshift space and to measure the redshifts of the clusters from the SDSS data. For optically confirmed clusters with good quality X-ray data we derived the X-ray flux, luminosity, and temperature from proper spectral fits, while the X-ray flux for clusters with low-quality X-ray data was obtained from the 2XMMi-DR3 catalogue. Results: The detection algorithm provides the photometric redshift of 530 galaxy clusters. Of these, 310 clusters have a spectroscopic redshift for at least one member galaxy. About 75 percent of the optically confirmed cluster sample are newly discovered X-ray clusters. Moreover, 301 systems are known as optically selected clusters in the literature while the remainder are new discoveries in X-ray and optical bands. The optically confirmed cluster sample spans a wide redshift range 0.03-0.70 (median z = 0.32). In this paper, we present the catalogue of X-ray-selected galaxy groups and clusters from the 2XMMi/SDSS galaxy cluster survey. The catalogue has two subsamples: (i) a cluster sample comprising 345 objects with their X-ray spectroscopic temperature and flux from the spectral fitting; and (ii) a cluster sample consisting of 185 systems with their X-ray flux from the 2XMMi-DR3 catalogue, because their X-ray data are insufficient for spectral fitting. For each cluster, the catalogue also provides the X-ray bolometric

  13. VizieR Online Data Catalog: Lynx-Cancer void sample galaxies HI data (Pustilnik+, 2016)

    NASA Astrophysics Data System (ADS)

    Pustilnik, S. A.; Martin, J.-M.

    2017-03-01

    The HI observations were made during the period 2007-2013 with the Nancay Radio Telescope (NRT). In Table A.1 we present the main parameters taken from NED1, SDSS2 or from the literature for all observed 45 void galaxies. ************************************************************************** * * * Sorry, but the author(s) never supplied the fits spectra as * * announced in the paper * * * ************************************************************************** (3 data files).

  14. Low Surface Brightness Galaxies Selected from the 40% Sky Area of the ALFALFA H I Survey. I. Sample and Statistical Properties

    NASA Astrophysics Data System (ADS)

    Du, Wei; Wu, Hong; Lam, Man I.; Zhu, Yinan; Lei, Fengjie; Zhou, Zhimin

    2015-06-01

    The population of low surface brightness (LSB) galaxies, which are objects with central surface brightnesses at least one magnitude fainter than the night sky, is crucial for understanding the extremes of galactic formation and evolution of the universe. As LSB galaxies are mostly rich in gas (H i), the α.40 Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) sample is one of the best survey combinations to select a sample of them in the local universe. Since the sky backgrounds are systematically overestimated for galactic images by the SDSS photometric pipeline, particularly for luminous galaxies or galaxies with extended LSB outskirts, in this paper, we above all estimated the sky backgrounds of SDSS images accurately in both the g and r bands for each galaxy in the α.40 SDSS DR7 sample, using a precise method of sky subtraction. Once subtracting the sky background, we did surface photometry with the Kron elliptical aperture using the SExtractor software and fitted geometric parameters with an exponential profile model using the Galfit software for each galactic image in the α.40 SDSS DR7 sample. Based on the photometric and geometric results, we further calculated the B-band central surface brightness, {{μ }0}(B), for each galaxy and ultimately defined a sample of LSB galaxies consisting of 1129 galaxies with {{μ }0}(B) > 22.5 mag arcsec-2 and the axis ratio b/a > 0.3 from the 12,423 α.40 SDSS DR7 galaxies. This H i-selected sample of LSB galaxies is a relatively unbiased sample of gas-rich and disk-dominated LSB galaxies, which is complete both in H i observation and the optical magnitude within the limit of the SDSS DR7 photometric survey. This LSB galactic sample spans from 22.5 to 28.3 in {{μ }0}(B) with a fraction of 4% fainter than 25.0 mag arcsec-2 in B-band central surface brightness and distributes from -27.0 to -12.3 mag in absolute magnitude in the B band (M(B)), including the 43 faintest galaxies (M(B) > -17.3 mag). This sample is a blue LSB

  15. Galaxy cluster X-ray luminosity scaling relations from a representative local sample (REXCESS)

    NASA Astrophysics Data System (ADS)

    Pratt, G. W.; Croston, J. H.; Arnaud, M.; Böhringer, H.

    2009-05-01

    We examine the X-ray luminosity scaling relations of 31 nearby galaxy clusters from the Representative XMM-Newton Cluster Structure Survey (REXCESS). The objects are selected only in X-ray luminosity, optimally sampling the cluster luminosity function. Temperatures range from 2 to 9 keV, and there is no bias toward any particular morphological type. To reduce measurement scatter we extract pertinent values in an aperture corresponding to R500, estimated using the tight correlation between YX (the product of gas mass and temperature) and total mass. The data exhibit power law relations between bolometric X-ray luminosity and temperature, YX and total mass, all with slopes that are significantly steeper than self-similar expectations. We examine the possible causes for the steepening, finding that structural variations have little effect and that the primary driver appears to be a systematic variation of the gas content with mass. Scatter about the relations is dominated in all cases by the presence of cool cores. The natural logarithmic scatter about the raw X-ray luminosity-temperature relation is about 70 per cent, and about the X-ray luminosity-YX relation it is 40 per cent. Systems with more morphological substructure show similar scatter about scaling relations than clusters with less substructure, due to the preponderance of cool core systems in the regular cluster subsample. Cool core and morphologically disturbed systems occupy distinct regions in the residual space with respect to the best fitting mean relation, the former lying systematically at the high luminosity side, the latter lying systematically at the low luminosity side. Simple exclusion of the central regions serves to reduce the scatter about the scaling relations by more than a factor of two. The scatter reduces by a similar amount with the use of the central gas density as a third parameter. Using YX as a total mass proxy, we derive a Malmquist bias-corrected local luminosity-mass relation and

  16. Galaxy-galaxy(-galaxy) lensing as a sensitive probe of galaxy evolution

    NASA Astrophysics Data System (ADS)

    Saghiha, H.; Hilbert, S.; Schneider, P.; Simon, P.

    2012-11-01

    Context. The gravitational lensing effect provides various ways to study the mass environment of galaxies. Aims: We investigate how galaxy-galaxy(-galaxy) lensing can be used to test models of galaxy formation and evolution. Methods: We consider two semi-analytic galaxy formation models based on the Millennium Run N-body simulation: the Durham model by Bower et al. (2006, MNRAS, 370, 645) and the Garching model by Guo et al. (2011, MNRAS, 413, 101). We generate mock lensing observations for the two models, and then employ Fast Fourier Transform methods to compute second- and third-order aperture statistics in the simulated fields for various galaxy samples. Results: We find that both models predict qualitatively similar aperture signals, but there are large quantitative differences. The Durham model predicts larger amplitudes in general. In both models, red galaxies exhibit stronger aperture signals than blue galaxies. Using these aperture measurements and assuming a linear deterministic bias model, we measure relative bias ratios of red and blue galaxy samples. We find that a linear deterministic bias is insufficient to describe the relative clustering of model galaxies below ten arcmin angular scales. Dividing galaxies into luminosity bins, the aperture signals decrease with decreasing luminosity for brighter galaxies, but increase again for fainter galaxies. This increase is likely an artifact due to too many faint satellite galaxies in massive group and cluster halos predicted by the models. Conclusions: Our study shows that galaxy-galaxy(-galaxy) lensing is a sensitive probe of galaxy evolution.

  17. OT1_hnetzer_1: Herschel study of black hole and galaxy evolution: The z<0.3 QUEST AGN sample.

    NASA Astrophysics Data System (ADS)

    Netzer, H.

    2010-07-01

    We propose 15.6 hours of Herschel time to secure high quality data,over the entire 70-500 micron range, for a group of 27 local, luminous active galactic nuclei (the QUEST AGN sample). The sources represent well the optically selected PG-QSO sample with redshifts up to z=0.3, and have been investigated, in great detail, in almost all other wavelength bands. The new far infrared (FIR) data set will be ideal to study various fundamental questions related to the connection and co-evolution of AGN and their host galaxies. Our previous Spitzer/IRS work on the sample has already revealed a clear relationship between the total AGN luminosity and the star formation rate (SFR) in their hosts. However, the previously undetected FIR sources may be situated in red-and-dead hosts and the Herschel observations can find these objects and allow a direct comparison of their AGN properties, like black hole (BH) mass and accretion rate, with those of the sources with high SFR. The observations will also provide unique information about the "intrinsic infrared AGN spectrum" with consequences to dust properties and distribution in such objects. Our sample is a needed ingredient in any Herschel-based studies that combine FIR-selected (IRAS, Spitzer, Herschel) and optically selected samples with their different biases. Its later comparison with similar high redshift observations will provide invaluable information about the cosmological evolution of AGN and star forming galaxies.

  18. Spectroscopic study in the visible and near infrared wavelength of an Hα-selected sample of star-forming galaxies at z = 0.84

    NASA Astrophysics Data System (ADS)

    Sánchez de Miguel, A.; Gallego, J.; Villar, V.; Pérez-González, P. G.; Zamorano, J.; Cardiel, N.; Acosta Pulido, J. A.

    2013-05-01

    In this work we study the physical properties of star-forming galaxies selected in an Hα near-infrared narrow-band survey tuned for redshift z=0.84 (Villar et al. 2008, 2011). Also, we present a sample at z˜1 with mass greater than 10^{10} M_{⊙} with Hα emission. The observations were carried out with WHT/LIRIS (see Sánchez de Miguel et al. 2011, in Highlights of Spanish Astrophysics VI). The rest of the data from the spectra archive of the RAINBOW Cosmological Survey database (Pérez-González et al. 2005, 2008; Barro et al. 2011ab). According to the redshift distribution of these galaxies, 65% of the galaxies are in a redshift range of 0.005. This velocity range corresponds to less than 25% of the effective volume. Which could be indicative of the presence of substructure. A total of 48 galaxies have detected Hα emission and other 12 show [NII]6584. To complete our multi-wavelength sample we found 23 galaxies with Hβ, [OIII]5007 or [OII]3727 detections. Using this photometry from ancillary data we will calculate nebular and stellar extinctions. We have calculated metallicities using the [NII]/Hα ratio and the Pettini & Pagel (2004) calibrations. The metallicity of samples are compatible with the local galaxies. We found that in all the diagnostic diagrams galaxies have similar properties to the local ones, except they are intrinsically brighter for the same equivalent width [OII]3727.

  19. The Herschel-ATLAS: a sample of 500 μm-selected lensed galaxies over 600 deg2

    NASA Astrophysics Data System (ADS)

    Negrello, M.; Amber, S.; Amvrosiadis, A.; Cai, Z.-Y.; Lapi, A.; Gonzalez-Nuevo, J.; De Zotti, G.; Furlanetto, C.; Maddox, S. J.; Allen, M.; Bakx, T.; Bussmann, R. S.; Cooray, A.; Covone, G.; Danese, L.; Dannerbauer, H.; Fu, H.; Greenslade, J.; Gurwell, M.; Hopwood, R.; Koopmans, L. V. E.; Napolitano, N.; Nayyeri, H.; Omont, A.; Petrillo, C. E.; Riechers, D. A.; Serjeant, S.; Tortora, C.; Valiante, E.; Verdoes Kleijn, G.; Vernardos, G.; Wardlow, J. L.; Baes, M.; Baker, A. J.; Bourne, N.; Clements, D.; Crawford, S. M.; Dye, S.; Dunne, L.; Eales, S.; Ivison, R. J.; Marchetti, L.; Michałowski, M. J.; Smith, M. W. L.; Vaccari, M.; van der Werf, P.

    2017-03-01

    We present a sample of 80 candidate strongly lensed galaxies with flux density above 100 mJy at 500 μm extracted from the Herschel Astrophysical Terahertz Large Area Survey, over an area of 600 deg2. Available imaging and spectroscopic data allow us to confirm the strong lensing in 20 cases and to reject it in one case. For other eight objects, the lensing scenario is strongly supported by the presence of two sources along the same line of sight with distinct photometric redshifts. The remaining objects await more follow-up observations to confirm their nature. The lenses and the background sources have median redshifts zL = 0.6 and zS = 2.5, respectively, and are observed out to zL = 1.2 and zS = 4.2. We measure the number counts of candidate lensed galaxies at 500 μm and compare them with theoretical predictions, finding a good agreement for a maximum magnification of the background sources in the range 10-20. These values are consistent with the magnification factors derived from the lens modelling of individual systems. The catalogue presented here provides sub-mm bright targets for follow-up observations aimed at exploiting gravitational lensing, to study with unprecedented details the morphological and dynamical properties of dusty star-forming regions in z ≳ 1.5 galaxies.

  20. Starburst galaxies

    NASA Technical Reports Server (NTRS)

    Weedman, Daniel W.

    1987-01-01

    The infrared properties of star-forming galaxies, primarily as determined by the Infrared Astronomy Satellite (IRAS), are compared to X-ray, optical, and radio properties. Luminosity functions are reviewed and combined with those derived from optically discovered samples using 487 Markarian galaxies with redshifts and published IRAS 60 micron fluxes, and 1074 such galaxies in the Center for Astrophysics redshift survey. It is found that the majority of infrared galaxies which could be detected are low luminosity sources already known from the optical samples, but non-infrared surveys have found only a very small fraction of the highest luminosity sources. Distributions of infrared to optical fluxes and available spectra indicate that the majority of IRAS-selected galaxies are starburst galaxies. Having a census of starburst galaxies and associated dust allow severl important global calculations. The source counts are predicted as a function of flux limits for both infrared and radio fluxes. These galaxies are found to be important radio sources at faint flux limits. Taking the integrated flux to z = 3 indicates that such galaxies are a significant component of the diffuse X-ray background, and could be the the dominant component depending on the nature of the X-ray spectra and source evolution.

  1. The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological analysis of the DR12 galaxy sample

    DOE PAGES

    Alam, Shadab; Ata, Metin; Bailey, Stephen; ...

    2017-03-28

    Here we present cosmological results from the final galaxy clustering data set of the Baryon Oscillation Spectroscopic Survey, part of the Sloan Digital Sky Survey III. Our combined galaxy sample comprises 1.2 million massive galaxies over an effective area of 9329 deg2 and volume of 18.7 Gpc3, divided into three partially overlapping redshift slices centred at effective redshifts 0.38, 0.51 and 0.61. We measure the angular diameter distance DM and Hubble parameter H from the baryon acoustic oscillation (BAO) method, in combination with a cosmic microwave background prior on the sound horizon scale, after applying reconstruction to reduce non-linear effectsmore » on the BAO feature. Using the anisotropic clustering of the pre-reconstruction density field, we measure the product DMH from the Alcock–Paczynski (AP) effect and the growth of structure, quantified by fσ8(z), from redshift-space distortions (RSD). We combine individual measurements presented in seven companion papers into a set of consensus values and likelihoods, obtaining constraints that are tighter and more robust than those from any one method; in particular, the AP measurement from sub-BAO scales sharpens constraints from post-reconstruction BAOs by breaking degeneracy between DM and H. Combined with Planck 2016 cosmic microwave background measurements, our distance scale measurements simultaneously imply curvature ΩK = 0.0003 ± 0.0026 and a dark energy equation-of-state parameter w = -1.01 ± 0.06, in strong affirmation of the spatially flat cold dark matter (CDM) model with a cosmological constant (ΛCDM). Our RSD measurements of fσ8, at 6 per cent precision, are similarly consistent with this model. When combined with supernova Ia data, we find H0 = 67.3 ± 1.0 km s-1 Mpc-1 even for our most general dark energy model, in tension with some direct measurements. Adding extra relativistic species as a degree of freedom loosens the constraint only slightly, to H0 = 67.8 ± 1.2km s-1 Mpc-1

  2. The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological analysis of the DR12 galaxy sample

    NASA Astrophysics Data System (ADS)

    Alam, Shadab; Ata, Metin; Bailey, Stephen; Beutler, Florian; Bizyaev, Dmitry; Blazek, Jonathan A.; Bolton, Adam S.; Brownstein, Joel R.; Burden, Angela; Chuang, Chia-Hsun; Comparat, Johan; Cuesta, Antonio J.; Dawson, Kyle S.; Eisenstein, Daniel J.; Escoffier, Stephanie; Gil-Marín, Héctor; Grieb, Jan Niklas; Hand, Nick; Ho, Shirley; Kinemuchi, Karen; Kirkby, David; Kitaura, Francisco; Malanushenko, Elena; Malanushenko, Viktor; Maraston, Claudia; McBride, Cameron K.; Nichol, Robert C.; Olmstead, Matthew D.; Oravetz, Daniel; Padmanabhan, Nikhil; Palanque-Delabrouille, Nathalie; Pan, Kaike; Pellejero-Ibanez, Marcos; Percival, Will J.; Petitjean, Patrick; Prada, Francisco; Price-Whelan, Adrian M.; Reid, Beth A.; Rodríguez-Torres, Sergio A.; Roe, Natalie A.; Ross, Ashley J.; Ross, Nicholas P.; Rossi, Graziano; Rubiño-Martín, Jose Alberto; Saito, Shun; Salazar-Albornoz, Salvador; Samushia, Lado; Sánchez, Ariel G.; Satpathy, Siddharth; Schlegel, David J.; Schneider, Donald P.; Scóccola, Claudia G.; Seo, Hee-Jong; Sheldon, Erin S.; Simmons, Audrey; Slosar, Anže; Strauss, Michael A.; Swanson, Molly E. C.; Thomas, Daniel; Tinker, Jeremy L.; Tojeiro, Rita; Magaña, Mariana Vargas; Vazquez, Jose Alberto; Verde, Licia; Wake, David A.; Wang, Yuting; Weinberg, David H.; White, Martin; Wood-Vasey, W. Michael; Yèche, Christophe; Zehavi, Idit; Zhai, Zhongxu; Zhao, Gong-Bo

    2017-09-01

    We present cosmological results from the final galaxy clustering data set of the Baryon Oscillation Spectroscopic Survey, part of the Sloan Digital Sky Survey III. Our combined galaxy sample comprises 1.2 million massive galaxies over an effective area of 9329 deg2 and volume of 18.7 Gpc3, divided into three partially overlapping redshift slices centred at effective redshifts 0.38, 0.51 and 0.61. We measure the angular diameter distance DM and Hubble parameter H from the baryon acoustic oscillation (BAO) method, in combination with a cosmic microwave background prior on the sound horizon scale, after applying reconstruction to reduce non-linear effects on the BAO feature. Using the anisotropic clustering of the pre-reconstruction density field, we measure the product DMH from the Alcock-Paczynski (AP) effect and the growth of structure, quantified by fσ8(z), from redshift-space distortions (RSD). We combine individual measurements presented in seven companion papers into a set of consensus values and likelihoods, obtaining constraints that are tighter and more robust than those from any one method; in particular, the AP measurement from sub-BAO scales sharpens constraints from post-reconstruction BAOs by breaking degeneracy between DM and H. Combined with Planck 2016 cosmic microwave background measurements, our distance scale measurements simultaneously imply curvature ΩK = 0.0003 ± 0.0026 and a dark energy equation-of-state parameter w = -1.01 ± 0.06, in strong affirmation of the spatially flat cold dark matter (CDM) model with a cosmological constant (ΛCDM). Our RSD measurements of fσ8, at 6 per cent precision, are similarly consistent with this model. When combined with supernova Ia data, we find H0 = 67.3 ± 1.0 km s-1 Mpc-1 even for our most general dark energy model, in tension with some direct measurements. Adding extra relativistic species as a degree of freedom loosens the constraint only slightly, to H0 = 67.8 ± 1.2 km s-1 Mpc-1. Assuming flat

  3. Non-thermal emission and dynamical state of massive galaxy clusters from CLASH sample

    NASA Astrophysics Data System (ADS)

    Pandey-Pommier, M.; Richard, J.; Combes, F.; Edge, A.; Guiderdoni, B.; Narasimha, D.; Bagchi, J.; Jacob, J.

    2016-12-01

    Massive galaxy clusters are the most violent large scale structures undergoing merger events in the Universe. Based upon their morphological properties in X-rays, they are classified as un-relaxed and relaxed clusters and often host (a fraction of them) different types of non-thermal radio emitting components, viz., 'haloes', 'mini-haloes', 'relics' and 'phoenix' within their Intra Cluster Medium (ICM). The radio haloes show steep (α = -1.2) and ultra steep (α < -1.5) spectral properties at low radio frequencies, giving important insights on the merger (pre or post) state of the cluster. Ultra steep spectrum radio halo emissions are rare and expected to be the dominating population to be discovered via LOFAR and SKA in the future. Further, the distribution of matter (morphological information), alignment of hot X-ray emitting gas from the ICM with the total mass (dark + baryonic matter) and the bright cluster galaxy (BCG) is generally used to study the dynamical state of the cluster. We present here a multi wavelength study on 14 massive clusters from the CLASH survey and show the correlation between the state of their merger in X-ray and spectral properties (1.4 GHz - 150 MHz) at radio wavelengths. Using the optical data we also discuss about the gas-mass alignment, in order to understand the interplay between dark and baryonic matter in massive galaxy clusters.

  4. THE BOSS EMISSION-LINE LENS SURVEY (BELLS). I. A LARGE SPECTROSCOPICALLY SELECTED SAMPLE OF LENS GALAXIES AT REDSHIFT {approx}0.5

    SciTech Connect

    Brownstein, Joel R.; Bolton, Adam S.; Pandey, Parul; Schlegel, David J.; Eisenstein, Daniel J.; Kochanek, Christopher S.; Connolly, Natalia; Maraston, Claudia; Seitz, Stella; Wake, David A.; Wood-Vasey, W. Michael; Brinkmann, Jon; Schneider, Donald P.; Weaver, Benjamin A.

    2012-01-01

    We present a catalog of 25 definite and 11 probable strong galaxy-galaxy gravitational lens systems with lens redshifts 0.4 {approx}< z {approx}< 0.7, discovered spectroscopically by the presence of higher-redshift emission lines within the Baryon Oscillation Spectroscopic Survey (BOSS) of luminous galaxies, and confirmed with high-resolution Hubble Space Telescope (HST) images of 44 candidates. Our survey extends the methodology of the Sloan Lens Advanced Camera for Surveys survey (SLACS) to higher redshift. We describe the details of the BOSS spectroscopic candidate detections, our HST ACS image processing and analysis methods, and our strong gravitational lens modeling procedure. We report BOSS spectroscopic parameters and ACS photometric parameters for all candidates, and mass-distribution parameters for the best-fit singular isothermal ellipsoid models of definite lenses. Our sample to date was selected using only the first six months of BOSS survey-quality spectroscopic data. The full five-year BOSS database should produce a sample of several hundred strong galaxy-galaxy lenses and in combination with SLACS lenses at lower redshift, strongly constrain the redshift evolution of the structure of elliptical, bulge-dominated galaxies as a function of luminosity, stellar mass, and rest-frame color, thereby providing a powerful test for competing theories of galaxy formation and evolution.

  5. Spot the difference. Impact of different selection criteria on observed properties of passive galaxies in zCOSMOS-20k sample

    NASA Astrophysics Data System (ADS)

    Moresco, M.; Pozzetti, L.; Cimatti, A.; Zamorani, G.; Bolzonella, M.; Lamareille, F.; Mignoli, M.; Zucca, E.; Lilly, S. J.; Carollo, C. M.; Contini, T.; Kneib, J.-P.; Le Fèvre, O.; Mainieri, V.; Renzini, A.; Scodeggio, M.; Bardelli, S.; Bongiorno, A.; Caputi, K.; Cucciati, O.; de la Torre, S.; de Ravel, L.; Franzetti, P.; Garilli, B.; Iovino, A.; Kampczyk, P.; Knobel, C.; Kovač, K.; Le Borgne, J.-F.; Le Brun, V.; Maier, C.; Pelló, R.; Peng, Y.; Perez-Montero, E.; Presotto, V.; Silverman, J. D.; Tanaka, M.; Tasca, L.; Tresse, L.; Vergani, D.; Barnes, L.; Bordoloi, R.; Cappi, A.; Diener, C.; Koekemoer, A. M.; Le Floc'h, E.; López-Sanjuan, C.; McCracken, H. J.; Nair, P.; Oesch, P.; Scarlata, C.; Scoville, N.; Welikala, N.

    2013-10-01

    Aims: We present the analysis of photometric, spectroscopic, and morphological properties for differently selected samples of passive galaxies up to z = 1 extracted from the zCOSMOS-20k spectroscopic survey. This analysis intends toexplore the dependence of galaxy properties on the selection criterion adopted, study the degree of contamination due to star-forming outliers, and provide a comparison between different commonly used selection criteria. This work is a first step to fully investigating the selection effects of passive galaxies for future massive surveys such as Euclid. Methods: We extracted from the zCOSMOS-20k catalog six different samples of passive galaxies, based on morphology (3336 "morphological" early-type galaxies), optical colors (4889 "red-sequence" galaxies and 4882 "red UVJ" galaxies), specific star-formation rate (2937 "quiescent" galaxies), a best fit to the observed spectral energy distribution (2603 "red SED" galaxies), and a criterion that combines morphological, spectroscopic, and photometric information (1530 "red & passive early-type galaxies"). For all the samples, we studied optical and infrared colors, morphological properties, specific star-formation rates (SFRs), and the equivalent widths of the residual emission lines; this analysis was performed as a function of redshift and stellar mass to inspect further possible dependencies. Results: We find that each passive galaxy sample displays a certain level of contamination due to blue/star-forming/nonpassive outliers. The morphological sample is the one that presents the higher percentage of contamination, with ~12-65% (depending on the mass range) of galaxies not located in the red sequence, ~25-80% of galaxies with a specific SFR up to ~25 times higher than the adopted definition of passive, and significant emission lines found in the median stacked spectra, at least for log (M/M⊙) < 10.25. The red & passive ETGs sample is the purest, with a percentage of contamination in color

  6. The SAMI Galaxy Survey: first 1000 galaxies

    NASA Astrophysics Data System (ADS)

    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.

  7. A MULTIWAVELENGTH STUDY OF A SAMPLE OF 70 {mu}m SELECTED GALAXIES IN THE COSMOS FIELD. II. THE ROLE OF MERGERS IN GALAXY EVOLUTION

    SciTech Connect

    Kartaltepe, Jeyhan S.; Sanders, D. B.; Le Floc'h, E.; Frayer, D. T.; Aussel, H.; Arnouts, S.; Ilbert, O.; Cassata, P.; Le Fevre, O.; Salvato, M.; Scoville, N. Z.; Capak, P.; Surace, J.; Yan, L.; Caputi, K.; Carollo, C. M.; Lilly, S.; Civano, F.; Hasinger, G.; Koekemoer, A. M.

    2010-09-20

    We analyze the morphological properties of a large sample of 1503 70 {mu}m selected galaxies in the COSMOS field spanning the redshift range 0.01 < z < 3.5 with a median redshift of 0.5 and an infrared luminosity range of 10{sup 8} < L{sub IR}(8 - 1000 {mu}m)< 10{sup 14} L{sub sun} with a median luminosity of 10{sup 11.4} L{sub sun}. In general, these galaxies are massive, with a stellar mass range of 10{sup 10}-10{sup 12} M{sub sun}, and luminous, with -25 < M{sub K} < -20. We find a strong correlation between the fraction of major mergers and L{sub IR}, with the fraction at the highest luminosity (L{sub IR} > 10{sup 12} L{sub sun}) being up to {approx}50%. We also find that the fraction of spirals drops dramatically with L{sub IR}. Minor mergers likely play a role in boosting the infrared luminosity for sources with low luminosities (L{sub IR} < 10{sup 11.5} L{sub sun}). The precise fraction of mergers in any given L{sub IR} bin varies by redshift due to sources at z > 1 being difficult to classify and subject to the effects of bandpass shifting; therefore, these numbers can only be considered lower limits. At z < 1, where the morphological classifications are most robust, major mergers clearly dominate the ULIRG population ({approx}50%-80%) and are important for the LIRG population ({approx}25%-40%). At z > 1, the fraction of major mergers is lower, but is at least 30%-40% for ULIRGs. In a comparison of our visual classifications with several automated classification techniques we find general agreement; however, the fraction of identified mergers is underestimated due to automated classification methods being sensitive to only certain timescales of a major merger. Although the general morphological trends agree with what has been observed for local (U)LIRGs, the fraction of major mergers is slightly lower than seen locally. This is in part due to the difficulty of identifying merger signatures at high redshift. The distribution of the U - V color of the

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

    SciTech Connect

    Stierwalt, S.; Armus, L.; Diaz-Santos, T.; Marshall, J.; Haan, S.; Howell, J.; Murphy, E. J.; Inami, H.; Petric, A. O.; Charmandaris, V.; Evans, A. S.; Iwasawa, K.; Kim, D. C.; Rich, J. A.; Spoon, H. W. W.; U, V.

    2014-08-01

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

  9. Hard X-Rays from a Complete Sample of the Brightest Ultraluminous Infrared Galaxies

    NASA Technical Reports Server (NTRS)

    Sanders, David B.

    2003-01-01

    We were awarded 70kS of XMM-Newton spacecraft time using the Epic pn camera to observe three ultraluminous infrared galaxies (ULIGs) in order to measure the spectral shape of their hard X-Ray emission, and to use this information to search for the presence of an highly obscured active galactic nucleus (AGN), and to separate out the contributions from a putative starburst. By observing three objects we hope to be able to better assess the role of AGN in the complete class of ULIGs and therefore to better constrain their contribution to the X-ray background. XMM-Newton was deemed to be better suited to our proposed measurements of ULIGs than the Chandra X-ray observatory due to its larger aperture and better sensitivity to hard (2-10 keV) X-rays.

  10. Arc Statistics with a sample of the Most X-Ray Luminous Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Kausch, Wolfgang; Schindler, Sabine; Erben, Thomas; Schwope, Axel; Wambsganss, Joachim

    2004-12-01

    We present a survey of 22 very X-ray luminous galaxy (Lx ≥ 0.5 × 1045 erg/sec in the 0.5-2keV band) clusters selected from the ROSAT Bright Survey. Because of their tremendous X-ray lumi- nosity all clusters are assumed to be very massive systems. In addition, the medium redshift range 0.1 ≤ z ≤ 0.52 was chosen, hence the probability for these clusters to act as gravitational lenses is very high. In these proceedings we present R- and V-band observations of the three clusters RBS325, RBS653 and RBS864 and discuss their photometric properties.

  11. Hard X-Rays from a Complete Sample of the Brightest Ultraluminous Infrared Galaxies

    NASA Technical Reports Server (NTRS)

    Sanders, David B.

    2003-01-01

    We were awarded 70kS of XMM-Newton spacecraft time using the Epic pn camera to observe three ultraluminous infrared galaxies (ULIGs) in order to measure the spectral shape of their hard X-Ray emission, and to use this information to search for the presence of an highly obscured active galactic nucleus (AGN), and to separate out the contributions from a putative starburst. By observing three objects we hope to be able to better assess the role of AGN in the complete class of ULIGs and therefore to better constrain their contribution to the X-ray background. XMM-Newton was deemed to be better suited to our proposed measurements of ULIGs than the Chandra X-ray observatory due to its larger aperture and better sensitivity to hard (2-10 keV) X-rays.

  12. Galaxy-galaxy and galaxy-CMB Lensing with SDSS-III BOSS galaxies

    NASA Astrophysics Data System (ADS)

    Singh, Sukhdeep; Mandelbaum, Rachel

    2017-01-01

    Weak lensing has emerged as an important cosmological probe for our understanding of dark matter and dark energy. The low redshift spectroscopic sample of SDSS-III BOSS survey, with a well-understood galaxy population is ideal to probe cosmology using galaxy-galaxy lensing and galaxy-CMB lensing. I will present results from two methods that combine information from lensing and galaxy clustering. The first involves combining lensing and galaxy clustering to directly measure galaxy bias and thus recover the matter correlation function, which is directly predicted from theory. Using scales where linear perturbation theory is valid, we carry out a joint analysis of galaxy-galaxy clustering, galaxy-galaxy lensing, and CMB-galaxy lensing, and constrain linear galaxy bias b=1.80+/-0.06, Omega_m=0.284+/-0.024, and relative calibration bias between CMB and galaxy lensing, b_l=0.82+/-0.15. The second method involves including information about redshift-space distortions to measure the E_G statistic to test gravitational physics at cosmological scales. This statistic is independent of galaxy bias and the amplitude of the matter power spectrum. Different theories of gravity predict a different E_G value, making it a clean and stringent test of GR at cosmological scales. Using the BOSS low redshift sample, we have measured E_G at z=0.27 with ~10% (15%) accuracy using galaxy (CMB) lensing, with results consistent with LCDM predictions.

  13. The Galaxy End Sequence

    NASA Astrophysics Data System (ADS)

    Eales, Stephen; de Vis, Pieter; Smith, Matthew W. L.; Appah, Kiran; Ciesla, Laure; Duffield, Chris; Schofield, Simon

    2017-03-01

    A common assumption is that galaxies fall in two distinct regions of a plot of specific star formation rate (SSFR) versus galaxy stellar mass: a star-forming galaxy main sequence (GMS) and a separate region of 'passive' or 'red and dead galaxies'. Starting from a volume-limited sample of nearby galaxies designed to contain most of the stellar mass in this volume, and thus representing the end-point of ≃12 billion years of galaxy evolution, we investigate the distribution of galaxies in this diagram today. We show that galaxies follow a strongly curved extended GMS with a steep negative slope at high galaxy stellar masses. There is a gradual change in the morphologies of the galaxies along this distribution, but there is no clear break between early-type and late-type galaxies. Examining the other evidence that there are two distinct populations, we argue that the 'red sequence' is the result of the colours of galaxies changing very little below a critical value of the SSFR, rather than implying a distinct population of galaxies. Herschel observations, which show at least half of early-type galaxies contain a cool interstellar medium, also imply continuity between early-type and late-type galaxies. This picture of a unitary population of galaxies requires more gradual evolutionary processes than the rapid quenching process needed to explain two distinct populations. We challenge theorists to predict quantitatively the properties of this 'Galaxy End Sequence'.

  14. THE SL2S GALAXY-SCALE LENS SAMPLE. III. LENS MODELS, SURFACE PHOTOMETRY, AND STELLAR MASSES FOR THE FINAL SAMPLE

    SciTech Connect

    Sonnenfeld, Alessandro; Suyu, Sherry H.; Treu, Tommaso; Gavazzi, Raphaël; Marshall, Philip J.

    2013-11-10

    We present Hubble Space Telescope (HST) imaging data and Canada-France-Hawaii Telescope (CFHT) near-infrared ground-based images for the final sample of 56 candidate galaxy-scale lenses uncovered in the CFHT Legacy Survey as part of the Strong Lensing in the Legacy Survey project. The new images are used to perform lens modeling, measure surface photometry, and estimate stellar masses of the deflector early-type galaxies (ETGs). Lens modeling is performed on the HST images (or CFHT when HST is not available) by fitting the spatially extended light distribution of the lensed features assuming a singular isothermal ellipsoid mass profile and by reconstructing the intrinsic source light distribution on a pixelized grid. Based on the analysis of systematic uncertainties and comparison with inference based on different methods, we estimate that our Einstein radii are accurate to ∼3%. HST imaging provides a much higher success rate in confirming gravitational lenses and measuring their Einstein radii than CFHT imaging does. Lens modeling with ground-based images, however, when successful, yields Einstein radius measurements that are competitive with space-based images. Information from the lens models is used together with spectroscopic information from companion Paper IV to classify the systems, resulting in a final sample of 39 confirmed (grade A) lenses and 17 promising candidates (grade B,C). This represents an increase of half an order of magnitude in sample size with respect to the sample of confirmed lenses studied in Papers I and II. The Einstein radii of the confirmed lenses in our sample span the range 5-15 kpc and are typically larger than those of other surveys, probing the mass in regions where the dark matter contribution is more important. Stellar masses are in the range 10{sup 11}-10{sup 12} M{sub ☉}, covering the range of massive ETGs. The redshifts of the main deflector span a range 0.3 ≤ z{sub d} ≤ 0.8, which nicely complements low

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Near-infrared photometry and stellar populations of first-ranked galaxies in a complete sample of nearby Abell clusters

    NASA Technical Reports Server (NTRS)

    Thuan, Trinx X.; Puschell, Jeffery J.

    1989-01-01

    Eighty-four brightest cluster members (BCMs) in the complete sample of high Galactic latitude nearby Abell clusters of Hoessel, Gunn, and Thuan (HGT) are investigated. The stellar populations in BCMs using near-infrared and optical-near-infrared colors are studied. Brighter BCMs have redder (J-K) and (V-K) colors, suggesting a metallicity increase in brighter galaxies. The larger dispersion of their colors implies that BCMs possess more heterogeneous stellar populations than their lower luminosity counterparts, the normal elliptical galaxies. Special attention is paid to BCMs associated with cooling flows. BCMs with larger accretion rates have bluer (V-K) colors due to ultraviolet excesses and are brighter in the visual wavelength region, but not in the infrared. It is suggested that part of the X-ray emitting cooling gas is converted into high- and intermediate-mass stars emitting in the blue and visible, but not in the infrared. The properties of BCMs as standard candles in the near-infrared are examined and compared with those in the optical.

  17. A Substantial Population of Red Galaxies at z > 2: Modeling of the Spectral Energy Distributions of an Extended Sample

    NASA Astrophysics Data System (ADS)

    Förster Schreiber, N. M.; van Dokkum, P. G.; Franx, M.; Labbé, I.; Rudnick, G.; Daddi, E.; Illingworth, G. D.; Kriek, M.; Moorwood, A. F. M.; Rix, H.-W.; Röttgering, H.; Trujillo, I.; van der Werf, P.; van Starkenburg, L.; Wuyts, S.

    2004-11-01

    We investigate the nature of the substantial population of high-redshift galaxies with Js-Ks>=2.3 colors recently discovered as part of our Faint Infrared Extragalactic Survey (FIRES). This color cut efficiently isolates galaxies at z>2 with red rest-frame optical colors (``distant red galaxies'' [DRGs]). We select Js-Ks>=2.3 objects in both FIRES fields, the ~2.5m×2.5m Hubble Deep Field-South (HDF-S) and the ~5'×5' field around the MS 1054-03 cluster at z=0.83; the surface densities at Ks,Vega<21 mag are 1.6+/-0.6 and 1.0+/-0.2 arcmin-2, respectively. We here discuss a subsample of 34 DRGs at 2<=z<=3.5: 11 at Ks,Vega<22.5 mag in HDF-S and 23 at Ks,Vega<21.7 mag in the MS 1054-03 field. This sample enables for the first time a robust assessment of the population properties of DRGs. We analyze the λ=0.3-2.2 μm spectral energy distributions (SEDs) constructed from our very deep near-infrared (NIR) and optical imaging collected at the ESO Very Large Telescope and from the Hubble Space Telescope. We develop diagnostics involving the I814-Js, Js-H, and H-Ks colors to argue that the red NIR colors of our DRG sample cannot be attributed solely to interstellar dust extinction and require for many the presence of an evolved stellar population with a prominent Balmer/4000 Å break. In the rest frame, the optical colors of DRGs fall within the envelope of normal nearby galaxies and the ultraviolet colors suggest a wide range in star formation activity and/or extinction. This is in stark contrast with the much bluer and more uniform SEDs of Lyman break galaxies (LBGs). From evolutionary synthesis modeling assuming constant star formation (CSF), we derive for the DRGs old ages, large extinctions, and high stellar masses, mass-to-light ratios, and star formation rates (SFRs). For solar metallicity, a Salpeter initial mass function (IMF) between 0.1 and 100 Msolar, and the Calzetti et al. extinction law, the median values for the HDF-S (MS 1054-03 field) sample are 1.7 (2

  18. Evidence for Ubiquitous High-equivalent-width Nebular Emission in z ~ 7 Galaxies: Toward a Clean Measurement of the Specific Star-formation Rate Using a Sample of Bright, Magnified Galaxies

    NASA Astrophysics Data System (ADS)

    Smit, R.; Bouwens, R. J.; Labbé, I.; Zheng, W.; Bradley, L.; Donahue, M.; Lemze, D.; Moustakas, J.; Umetsu, K.; Zitrin, A.; Coe, D.; Postman, M.; Gonzalez, V.; Bartelmann, M.; Benítez, N.; Broadhurst, T.; Ford, H.; Grillo, C.; Infante, L.; Jimenez-Teja, Y.; Jouvel, S.; Kelson, D. D.; Lahav, O.; Maoz, D.; Medezinski, E.; Melchior, P.; Meneghetti, M.; Merten, J.; Molino, A.; Moustakas, L. A.; Nonino, M.; Rosati, P.; Seitz, S.

    2014-03-01

    Growing observational evidence indicates that nebular line emission has a significant impact on the rest-frame optical fluxes of z ~ 5-7 galaxies. This line emission makes z ~ 5-7 galaxies appear more massive, with lower specific star-formation rates (sSFRs). However, corrections for this line emission have been difficult to perform reliably because of huge uncertainties on the strength of such emission at z >~ 5.5. In this paper, we present the most direct observational evidence thus far for ubiquitous high-equivalent-width (EW) [O III] + Hβ line emission in Lyman-break galaxies at z ~ 7, and we present a strategy for an improved measurement of the sSFR at z ~ 7. We accomplish this through the selection of bright galaxies in the narrow redshift window z ~ 6.6-7.0 where the Spitzer/Infrared Array Camera (IRAC) 4.5 μm flux provides a clean measurement of the stellar continuum light, in contrast with the 3.6 μm flux, which is contaminated by the prominent [O III] + Hβ lines. To ensure a high signal-to-noise ratio for our IRAC flux measurements, we consider only the brightest (H 160 < 26 mag) magnified galaxies we have identified behind galaxy clusters. It is remarkable that the mean rest-frame optical color for our bright seven-source sample is very blue, [3.6]-[4.5] = -0.9 ± 0.3. Such blue colors cannot be explained by the stellar continuum light and require that the rest-frame EW of [O III] + Hβ is greater than 637 Å for the average source. The four bluest sources from our seven-source sample require an even more extreme EW of 1582 Å. We can also set a robust lower limit of >~ 4 Gyr-1 on the sSFR of our sample based on the mean spectral energy distribution.

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

    SciTech Connect

    Stierwalt, S.; Armus, L.; Surace, J. A.; Inami, H.; Petric, A. O.; Diaz-Santos, T.; Haan, S.; Howell, J.; Marshall, J.; Charmandaris, V.; Kim, D. C.; Mazzarella, J. M.; Chan, B.; Spoon, H. W. W.; Veilleux, S.; Evans, A.; Sanders, D. B.; Appleton, P.; Bothun, G.; Bridge, C. R.; and others

    2013-05-01

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

  20. Study of the emission of PAHs in 7.7μm and IR emission for a sample of galaxies at high redshift

    NASA Astrophysics Data System (ADS)

    Zambrano, R.; Higuera G., M. A.

    2017-07-01

    This study investigates a possible correlation between the star formation rate (SFR) from the PAHs emission in the line of 7.7μm and IR emission for a sample of galaxies at high redshift obtained by the Spitzer Space Telescope. Profiles emission of PAHs for the sample were extracted using the PAHFIT tool, designed to decomposing Spitzer IRS spectra and written in the IDL programming language, in order to determine the luminosity and the star formation rate for each of the galaxies.

  1. The clustering of the SDSS DR7 main Galaxy sample - I. A 4 per cent distance measure at z = 0.15

    NASA Astrophysics Data System (ADS)

    Ross, Ashley J.; Samushia, Lado; Howlett, Cullan; Percival, Will J.; Burden, Angela; Manera, Marc

    2015-05-01

    We create a sample of spectroscopically identified galaxies with z < 0.2 from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7), covering 6813 deg2. Galaxies are chosen to sample the highest mass haloes, with an effective bias of 1.5, allowing us to construct 1000 mock galaxy catalogues (described in Paper II), which we use to estimate statistical errors and test our methods. We use an estimate of the gravitational potential to `reconstruct' the linear density fluctuations, enhancing the baryon acoustic oscillation (BAO) signal in the measured correlation function and power spectrum. Fitting to these measurements, we determine DV(zeff = 0.15) = (664 ± 25)(rd/rd, fid) Mpc; this is a better than 4 per cent distance measurement. This `fills the gap' in BAO distance ladder between previously measured local and higher redshift measurements, and affords significant improvement in constraining the properties of dark energy. Combining our measurement with other BAO measurements from Baryon Oscillation Spectroscopic Survey and 6-degree Field Galaxy Redshift Survey galaxy samples provides a 15 per cent improvement in the determination of the equation of state of dark energy and the value of the Hubble parameter at z = 0 (H0). Our measurement is fully consistent with the Planck results and the Λ cold dark matter concordance cosmology, but increases the tension between Planck+BAO H0 determinations and direct H0 measurements.

  2. THE COOL INTERSTELLAR MEDIUM IN ELLIPTICAL GALAXIES. II. GAS CONTENT IN THE VOLUME-LIMITED SAMPLE AND RESULTS FROM THE COMBINED ELLIPTICAL AND LENTICULAR SURVEYS

    SciTech Connect

    Welch, Gary A.; Sage, Leslie J.; Young, Lisa M. E-mail: lsage@astro.umd.ed

    2010-12-10

    We report new observations of atomic and molecular gas in a volume-limited sample of elliptical galaxies. Combining the elliptical sample with an earlier and similar lenticular one, we show that cool gas detection rates are very similar among low-luminosity E and S0 galaxies but are much higher among luminous S0s. Using the combined sample we revisit the correlation between cool gas mass and blue luminosity which emerged from our lenticular survey, finding strong support for previous claims that the molecular gas in ellipticals and lenticulars has different origins. Unexpectedly, however, and contrary to earlier claims, the same is not true for atomic gas. We speculate that both the active galactic nucleus feedback and merger paradigms might offer explanations for differences in detection rates, and might also point toward an understanding of why the two gas phases could follow different evolutionary paths in Es and S0s. Finally, we present a new and puzzling discovery concerning the global mix of atomic and molecular gas in early-type galaxies. Atomic gas comprises a greater fraction of the cool interstellar medium in more gas-rich galaxies, a trend which can be plausibly explained. The puzzle is that galaxies tend to cluster around molecular-to-atomic gas mass ratios near either 0.05 or 0.5.

  3. High-Resolution Near-Infrared Spectroscopy of an Equivalent Width-Selected Sample of Starbursting Dwarf Galaxies

    NASA Technical Reports Server (NTRS)

    Maseda, Michael V.; VanDerWeL, Arjen; DaChuna, Elisabete; Rix, Hans-Walter; Pacafichi, Camilla; Momcheva, Ivelina; Brammer, Gabriel B.; Franx, Marijn; VanDokkum, Pieter; Bell, Eric F.; Ferguson, Harry C.; Fumagalli, Mattia; Grogin, Norman A.; Kocevski, Dale D.; Koekemoer, Anton M.; Lundgren, Britt F.; Marchesini, Danilo; Nelson, Erica J.; Patel, Shannon; Skelton, Rosalind E.; Straughn, Amber N.; Trump, Jonathan R.; Weiner, Benjamin J.; Whitaker, Katherine E.; Wuyts, Stijn

    2013-01-01

    Spectroscopic observations from the Large Binocular Telescope and the Very Large Telescope reveal kinematically narrow lines (approx. 50 km/s) for a sample of 14 Extreme Emission Line Galaxies (EELGs) at redshifts 1.4 < zeta < 2.3. These measurements imply that the total dynamical masses of these systems are low ( 3 × 10(exp 9) M). Their large [O III]5007 equivalent widths (500 - 1100 A) and faint blue continuum emission imply young ages of 10-100 Myr and stellar masses of 10(exp 8)-10(exp 9) M, confirming the presence of a violent starburst. The stellar mass formed in this vigorous starburst phase thus represents a large fraction of the total (dynamical) mass, without a significantly massive underlying population of older stars. The occurrence of such intense events in shallow potentials strongly suggests that supernova-driven winds must be of critical importance in the subsequent evolution of these systems.

  4. Substructure in a Flux-limited Sample of X-ray Clusters of Galaxies: Wavelet Decomposition of ROSAT PSPC Data

    NASA Astrophysics Data System (ADS)

    Vrtilek, J. M.; David, L. P.; Vikhlinin, A.; Forman, W.; Jones, C.

    1997-12-01

    The presence of substructure within clusters of galaxies has substantial implications for our understanding of cluster evolution as well as for fundamental questions in cosmology. We discuss our analysis of structure in clusters based on wavelet decomposition applied to ROSAT PSPC data. Clusters that span a wide range in temperature and amount of substructure are selected from the flux-limited sample of Edge et al. (1990 MNRAS 245, 559). In the analysis, the PSPC data are exposure-corrected by the methods described in Snowden et al. (1994 ApJ 424, 714) and background subtraction is achieved directly in the wavelet decomposition. The data are rebinned so that the characteristic scales in the analysis correspond to a uniform physical scale in the clusters. We interpret our results in the context of recent models.

  5. The ROSAT-ESO flux limited X-ray (REFLEX) galaxy cluster survey. I. The construction of the cluster sample

    NASA Astrophysics Data System (ADS)

    Böhringer, H.; Schuecker, P.; Guzzo, L.; Collins, C. A.; Voges, W.; Schindler, S.; Neumann, D. M.; Cruddace, R. G.; De Grandi, S.; Chincarini, G.; Edge, A. C.; MacGillivray, H. T.; Shaver, P.

    2001-04-01

    We discuss the construction of an X-ray flux-limited sample of galaxy clusters, the REFLEX survey catalogue, to be used for cosmological studies. This cluster identification and redshift survey was conducted in the frame of an ESO key programme and is based on candidates selected from the southern part of the ROSAT All-Sky Survey (RASS). For the first cluster candidate selection from a flux-limited RASS source list, we make use of optical data from the COSMOS digital catalogue produced from the scans of the UK-Schmidt plates. To ensure homogeneity of the sample construction process, this selection is based only on this one well-defined optical data base. The nature of the candidates selected in this process is subsequently checked by a more detailed evaluation of the X-ray and optical source properties and available literature data. The final identification and the redshift is then based on optical spectroscopic follow-up observations. In this paper we document the process by which the primary cluster candidate catalogue is constructed prior to the optical follow-up observations. We describe the reanalysis of the RASS source catalogue which enables us to impose a proper flux limit cut to the X-ray source list without introducing a severe bias against extended sources. We discuss the correlation of the X-ray and optical (COSMOS) data to find galaxy density enhancements at the RASS X-ray source positions and the further evaluation of the nature of these cluster candidates. Based also on the results of the follow-up observations we provide a statistical analysis of the completeness and contamination of the final cluster sample and show results on the cluster number counts. The final sample of identified X-ray clusters reaches a flux limit of 3 10-12 erg s-1 cm-2 in the 0.1-2.4 keV band and comprises 452 clusters in an area of 4.24 ster. The results imply a completeness of the REFLEX cluster sample well in excess of 90%. We also derive for the first time an upper limit

  6. The AGN content of ultraluminous IR galaxies: High resolution VLA imaging of the IRAS 1 Jy ULIRG sample

    NASA Astrophysics Data System (ADS)

    Nagar, N. M.; Wilson, A. S.; Falcke, H.; Veilleux, S.; Maiolino, R.

    2003-10-01

    This paper presents the results of a high resolution radio imaging survey of 83 of the 118 ultraluminous infrared galaxies (ULIRGs) in the IRAS 1 Jy ULIRG sample. We have observed these ULIRGs at 15 GHz with the Very Large Array (VLA). We find that ~ 75% of Seyferts (both type 1 and 2) and LINERs have radio nuclei which are compact at our 150 mas resolution. The detection rate of H II nuclei is significantly lower (32%); the detections among these are preferentially H II + LINER/Seyfert composite nuclei. Among ULIRGs with multiple optical or near-IR nuclei our observations detected only one (or no) nucleus; in these the radio detection is typically towards the brightest near-IR nucleus. The compactness of the radio sources, the higher detection rates in AGN-type nuclei than H II nuclei, the preferential detection of nuclei with unresolved point sources in the near-IR, the low soft X-ray to nuclear radio luminosity ratio (arguing against thermal emission powering the radio nuclei), and the lack of correlation between radio power and Hα luminosity, all support an origin of the detected radio nuclei in AGN related activity. This result is especially interesting for LINER ULIRGs for which signatures of AGNs have often been ambiguous in other wavebands. Such a high incidence of AGN would provide, for the first time, a large sample in which to study the interplay between AGN, starbursts, and galaxy mergers. Table 1 is also available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/a+A/409/115

  7. Evolution of the anti-truncated stellar profiles of S0 galaxies since z = 0.6 in the SHARDS survey. I. Sample and methods

    NASA Astrophysics Data System (ADS)

    Borlaff, Alejandro; Eliche-Moral, M. Carmen; Beckman, John E.; Ciambur, Bogdan C.; Pérez-González, Pablo G.; Barro, Guillermo; Cava, Antonio; Cardiel, Nicolas

    2017-08-01

    Context. The controversy about the origin of the structure of early-type S0-E/S0 galaxies may be due to the difficulty of comparing surface brightness profiles with different depths, photometric corrections and point spread function (PSF) effects (which are almost always ignored). Aims: We aim to quantify the properties of Type-III (anti-truncated) discs in a sample of S0 galaxies at 0.2 sample selection and describe in detail the methods to robustly trace the structure in their outskirts and correct for PSF effects. Methods: We have selected and classified a sample of 150 quiescent galaxies at 0.2 galaxies. We have corrected their surface brightness profiles for PSF distortions and analysed the biases in the structural and photometric parameters when the PSF correction is not applied. Additionally, we have developed Elbow, an automatic statistical method to determine whether a possible break is significant - or not - and its type. We have made this method publicly available. Results: We find 14 anti-truncated S0-E/S0 galaxies in the range 0.2 sample). This fraction is similar to the those reported in the local Universe. In our sample, 25% of the Type-III breaks observed in PSF-uncorrected profiles are artifacts, and their profiles turn into a Type I after PSF correction. PSF effects also soften Type-II profiles. We find that the profiles of Type-I S0 and E/S0 galaxies of our sample are compatible with the inner profiles of the Type-III, in contrast with the outer profiles. Conclusions: We have obtained the first robust and reliable sample of 14 anti-truncated S0-E/S0 galaxies beyond the local Universe, in the range 0.2 galaxy discs even in the case of the narrow PSF of HST/ACS images, so future studies on the subject

  8. ENVIRONMENTAL DEPENDENCE OF ALL OF THE FIVE-BAND LUMINOSITIES FOR THE APPARENT-MAGNITUDE-LIMITED MAIN GALAXY SAMPLE OF THE SDSS DR7

    SciTech Connect

    Deng Xinfa

    2012-01-15

    In this study, I use the apparent-magnitude-limited Main galaxy sample of the Sloan Digital Sky Survey Data Release 7 and investigate the environmental dependence of all of the five-band luminosities. To decrease the radial selection effect, I divide the whole sample into many subsamples with a redshift binning size of {Delta}z = 0.01 and analyze the environmental dependence of all of the five-band luminosities of subsamples in each redshift bin. It turns out that luminous galaxies in M{sub u} (the u-band absolute magnitude) exist preferentially in low-density regions of the universe, while faint galaxies in M{sub u} are located preferentially in high-density regions, especially in the redshift range 0.05 {<=} z {<=} 0.10.

  9. The BOSS Emission-Line Lens Survey (BELLS). I. A Large Spectroscopically Selected Sample of Lens Galaxies at Redshift ~0.5

    NASA Astrophysics Data System (ADS)

    Brownstein, Joel R.; Bolton, Adam S.; Schlegel, David J.; Eisenstein, Daniel J.; Kochanek, Christopher S.; Connolly, Natalia; Maraston, Claudia; Pandey, Parul; Seitz, Stella; Wake, David A.; Wood-Vasey, W. Michael; Brinkmann, Jon; Schneider, Donald P.; Weaver, Benjamin A.

    2012-01-01

    We present a catalog of 25 definite and 11 probable strong galaxy-galaxy gravitational lens systems with lens redshifts 0.4 <~ z <~ 0.7, discovered spectroscopically by the presence of higher-redshift emission lines within the Baryon Oscillation Spectroscopic Survey (BOSS) of luminous galaxies, and confirmed with high-resolution Hubble Space Telescope (HST) images of 44 candidates. Our survey extends the methodology of the Sloan Lens Advanced Camera for Surveys survey (SLACS) to higher redshift. We describe the details of the BOSS spectroscopic candidate detections, our HST ACS image processing and analysis methods, and our strong gravitational lens modeling procedure. We report BOSS spectroscopic parameters and ACS photometric parameters for all candidates, and mass-distribution parameters for the best-fit singular isothermal ellipsoid models of definite lenses. Our sample to date was selected using only the first six months of BOSS survey-quality spectroscopic data. The full five-year BOSS database should produce a sample of several hundred strong galaxy-galaxy lenses and in combination with SLACS lenses at lower redshift, strongly constrain the redshift evolution of the structure of elliptical, bulge-dominated galaxies as a function of luminosity, stellar mass, and rest-frame color, thereby providing a powerful test for competing theories of galaxy formation and evolution. Based on observations made 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 12209. Based on spectroscopic data from the Baryon Oscillation Spectroscopic Survey of the Sloan Digital Sky Survey III.

  10. STELLAR POPULATIONS FROM SPECTROSCOPY OF A LARGE SAMPLE OF QUIESCENT GALAXIES AT Z > 1: MEASURING THE CONTRIBUTION OF PROGENITOR BIAS TO EARLY SIZE GROWTH

    SciTech Connect

    Belli, Sirio; Ellis, Richard S.; Newman, Andrew B.

    2015-02-01

    We analyze the stellar populations of a sample of 62 massive (log M {sub *}/M {sub ☉} > 10.7) galaxies in the redshift range 1 < z < 1.6, with the main goal of investigating the role of recent quenching in the size growth of quiescent galaxies. We demonstrate that our sample is not biased toward bright, compact, or young galaxies, and thus is representative of the overall quiescent population. Our high signal-to-noise ratio Keck/LRIS spectra probe the rest-frame Balmer break region that contains important absorption line diagnostics of recent star formation activity. We obtain improved measures of the various stellar population parameters, including the star formation timescale τ, age, and dust extinction, by fitting templates jointly to both our spectroscopic and broadband photometric data. We identify which quiescent galaxies were recently quenched and backtrack their individual evolving trajectories on the UVJ color-color plane finding evidence for two distinct quenching routes. By using sizes measured in the previous paper of this series, we confirm that the largest galaxies are indeed among the youngest at a given redshift. This is consistent with some contribution to the apparent growth from recent arrivals, an effect often called progenitor bias. However, we calculate that recently quenched objects can only be responsible for about half the increase in average size of quiescent galaxies over a 1.5 Gyr period, corresponding to the redshift interval 1.25 < z < 2. The remainder of the observed size evolution arises from a genuine growth of long-standing quiescent galaxies.

  11. SDSS-II Supernova survey. An analysis of the largest sample of type IA supernovae and correlations with host-galaxy spectral properties

    SciTech Connect

    Wolf, Rachel C.; D’Andrea, Chris B.; Gupta, Ravi R.; Sako, Masao; Fischer, John A.; Kessler, Rick; Jha, Saurabh W.; March, Marisa C.; Scolnic, Daniel M.; Fischer, Johanna-Laina; Campbell, Heather; Nichol, Robert C.; Olmstead, Matthew D.; Richmond, Michael; Schneider, Donald P.; Smith, Mathew

    2016-04-20

    Using the largest single-survey sample of Type Ia supernovae (SNe Ia) to date, we study the relationship between properties of SNe Ia and those of their host galaxies, focusing primarily on correlations with Hubble residuals (HR). Our sample consists of 345 photometrically-classified or spectroscopicallyconfirmed SNe Ia discovered as part of the SDSS-II Supernova Survey (SDSS-SNS). This analysis utilizes host-galaxy spectroscopy obtained during the SDSS-I/II spectroscopic survey and from an ancillary program on the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) that obtained spectra for nearly all host galaxies of SDSS-II SN candidates. In addition, we use photometric hostgalaxy properties from the SDSS-SNS data release (Sako et al. 2014) such as host stellar mass and star-formation rate. We confirm the well-known relation between HR and host-galaxy mass and find a 3.6σ significance of a non-zero linear slope. We also recover correlations between HR and hostgalaxy gas-phase metallicity and specific star-formation rate as they are reported in the literature. With our large dataset, we examine correlations between HR and multiple host-galaxy properties simultaneously and find no evidence of a significant correlation. We also independently analyze our spectroscopically-confirmed and photometrically-classified SNe Ia and comment on the significance of similar combined datasets for future surveys.

  12. Chandra measurements of a complete sample of X-ray luminous galaxy clusters: the luminosity-mass relation

    NASA Astrophysics Data System (ADS)

    Giles, P. A.; Maughan, B. J.; Dahle, H.; Bonamente, M.; Landry, D.; Jones, C.; Joy, M.; Murray, S. S.; van der Pyl, N.

    2017-02-01

    We present the results of work involving a statistically complete sample of 34 galaxy clusters, in the redshift range 0.15 ≤ z ≤ 0.3 observed with Chandra. We investigate the luminosity-mass (LM) relation for the cluster sample, with the masses obtained via a full hydrostatic mass analysis. We utilize a method to fully account for selection biases when modelling the LM relation, and find that the LM relation is significantly different from the relation modelled when not account for selection effects. We find that the luminosity of our clusters is 2.2 ± 0.4 times higher (when accounting for selection effects) than the average for a given mass and its mass is 30 per cent lower than the population average for a given luminosity. Equivalently, using the LM relation measured from this sample without correcting for selection biases would lead to the underestimation by 40 per cent of the average mass of a cluster with a given luminosity. Comparing the hydrostatic masses to mass estimates determined from the YX parameter, we find that they are entirely consistent, irrespective of the dynamical state of the cluster.

  13. A new sample of X-ray selected narrow emission-line galaxies. II. Looking for True Seyfert 2

    NASA Astrophysics Data System (ADS)

    Pons, E.; Watson, M. G.

    2016-10-01

    A sample of X-ray and optically selected narrow emission-line galaxies (769 sources) from the 3XMM catalogue cross-correlated with SDSS (DR9) catalogue has been studied. Narrow-emission line active galactic nuclei (AGN; type-2) have been selected on the basis of their emission line ratios and/or X-ray luminosity. We have looked for X-ray unobscured type-2 AGN. As X-ray spectra were not available for our whole sample, we have checked the reliability of using the X-ray hardness ratio (HR) as a probe of the level of obscuration and we found a very good agreement with full spectral fitting results, with only 2% of the sources with apparently unobscured HR turning out to have an obscured spectrum. Despite the fact that type-2 AGN are supposed to be absorbed based on the Unified Model, about 60% of them show no sign or very low level of X-ray obscuration. After subtraction of contaminants to the sample, that is Narrow-Line Seyfert 1 and Compton-thick AGN, the fraction of unobscured Sy2 drops to 47%. For these sources, we were able to rule out dust reddening and variability for most of them as an explanation of the absence of optical broad emission-lines. The main explanations remaining are the dilution of weak/very broad emission-lines by the host galaxy and the intrinsic absence of the broad-line region (BLR) due to low accretion rates (i.e. True Sy2). However, the number of True Sy2 strongly depends on the method used to verify the intrinsic lack of broad lines. Indeed using the optical continuum luminosity to predict the BLR properties gives a much larger fraction of True Sy2 (about 90% of the unobscured Sy2 sample) than the use of the X-ray 2 keV luminosity (about 20%). Nevertheless the number of AGN we securely detected as True Sy2 is at least three times larger that the previously confirmed number of True Sy2.

  14. A Comprehensive Study of 2000 Narrow Line Seyfert 1 Galaxies from the Sloan Digital Sky Survey. I. The Sample

    NASA Astrophysics Data System (ADS)

    Zhou, Hongyan; Wang, Tinggui; Yuan, Weimin; Lu, Honglin; Dong, Xiaobo; Wang, Junxian; Lu, Youjun

    2006-09-01

    This is the first paper in a series dedicated to the study of the emission-line and continuum properties of narrow line Seyfert 1 galaxies (NLS1s). We carried out a systematic search for NLS1s from objects assigned as ``QSOs'' or ``galaxies'' in the spectroscopic sample of the Sloan Digital Sky Survey Data Release 3 (SDSS DR3) by a careful modeling of their emission lines and continua. The result is a uniform sample comprising ~2000 NLS1s. This sample dramatically increases the number of known NLS1s by a factor of ~10 over previous compilations. This paper presents the parameters of the prominent emission lines and continua, which were measured accurately with typical uncertainties <10%. Taking advantage of such an unprecedented large and uniform sample with accurately measured spectral parameters, we carried out various statistical analyses, some of which were only possible for the first time. The main results found are as follows. (1) Within the overall Seyfert 1 population, the incidence of NLS1s is strongly dependent on the optical, X-ray, and radio luminosities as well as the radio loudness. The fraction of NLS1s peaks around SDSS g-band absolute magnitude Mg~-22 mag in the optical and ~1043.2 ergs s-1 in the soft X-ray band, and decreases quickly as the radio loudness increases. (2) On average the relative Fe II emission, R4570=Fe II λλ4434-4684/Hβ, in NLS1s is about twice that in normal active galactic nuclei (AGNs) and is anticorrelated with the broad component width of the Balmer emission lines. (3) The well-known anticorrelation between the width of broad low-ionization lines and the soft X-ray spectral slope for broad line AGNs extends down to FWHM~1000 km s-1 in NLS1s, but the trend appears to reverse at still smaller line widths. (4) The equivalent width of Hβ and Fe II emission lines are strongly correlated with the Hβ and continuum luminosities. (5) We do not find any difference between NLS1s and normal AGNs in regard to the narrow line region

  15. The ATLAS3D project - I. A volume-limited sample of 260 nearby early-type galaxies: science goals and selection criteria

    NASA Astrophysics Data System (ADS)

    Cappellari, Michele; Emsellem, Eric; Krajnović, Davor; McDermid, Richard M.; Scott, Nicholas; Verdoes Kleijn, G. A.; Young, Lisa M.; Alatalo, Katherine; Bacon, R.; Blitz, Leo; Bois, Maxime; Bournaud, Frédéric; Bureau, M.; Davies, Roger L.; Davis, Timothy A.; de Zeeuw, P. T.; Duc, Pierre-Alain; Khochfar, Sadegh; Kuntschner, Harald; Lablanche, Pierre-Yves; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Serra, Paolo; Weijmans, Anne-Marie

    2011-05-01

    The ATLAS3D project is a multiwavelength survey combined with a theoretical modelling effort. The observations span from the radio to the millimetre and optical, and provide multicolour imaging, two-dimensional kinematics of the atomic (H I), molecular (CO) and ionized gas (Hβ, [O III] and [N I]), together with the kinematics and population of the stars (Hβ, Fe5015 and Mg b), for a carefully selected, volume-limited (1.16 × 105 Mpc3) sample of 260 early-type (elliptical E and lenticular S0) galaxies (ETGs). The models include semi-analytic, N-body binary mergers and cosmological simulations of galaxy formation. Here we present the science goals for the project and introduce the galaxy sample and the selection criteria. The sample consists of nearby (D < 42 Mpc, |δ- 29°| < 35°, |b| > 15°) morphologically selected ETGs extracted from a parent sample of 871 galaxies (8 per cent E, 22 per cent S0 and 70 per cent spirals) brighter than MK < -21.5 mag (stellar mass M★≳ 6 ×109 M⊙). We analyse possible selection biases and we conclude that the parent sample is essentially complete and statistically representative of the nearby galaxy population. We present the size-luminosity relation for the spirals and ETGs and show that the ETGs in the ATLAS3D sample define a tight red sequence in a colour-magnitude diagram, with few objects in the transition from the blue cloud. We describe the strategy of the SAURON integral field observations and the extraction of the stellar kinematics with the pPXF method. We find typical 1σ errors of ΔV≈ 6 km s-1, Δσ≈ 7 km s-1, Δh3≈Δh4≈ 0.03 in the mean velocity, the velocity dispersion and Gauss-Hermite (GH) moments for galaxies with effective dispersion σe≳ 120 km s-1. For galaxies with lower σe (≈40 per cent of the sample) the GH moments are gradually penalized by pPXF towards zero to suppress the noise produced by the spectral undersampling and only V and σ can be measured. We give an overview of the

  16. The SL2S Galaxy-scale Lens Sample. IV. The Dependence of the Total Mass Density Profile of Early-type Galaxies on Redshift, Stellar Mass, and Size

    NASA Astrophysics Data System (ADS)

    Sonnenfeld, Alessandro; Treu, Tommaso; Gavazzi, Raphaël; Suyu, Sherry H.; Marshall, Philip J.; Auger, Matthew W.; Nipoti, Carlo

    2013-11-01

    We present optical and near-infrared spectroscopy obtained at Keck, Very Large Telescope, and Gemini for a sample of 36 secure strong gravitational lens systems and 17 candidates identified as part of the Strong Lensing Legacy Survey. The deflectors are massive early-type galaxies in the redshift range zd = 0.2-0.8, while the lensed sources are at zs = 1-3.5. We combine these data with photometric and lensing measurements presented in the companion paper III and with lenses from the Sloan Lens Advanced Camera for Surveys and Lènses Structure and Dynamics surveys to investigate the cosmic evolution of the internal structure of massive early-type galaxies over half the age of the universe. We study the dependence of the slope of the total mass density profile, γ' (\\rho (r)\\propto r^{-\\gamma ^{\\prime }}), on stellar mass, size, and redshift. We find that two parameters are sufficient to determine γ' with less than 6% residual scatter. At fixed redshift, γ' depends solely on the surface stellar mass density ∂γ'/∂Σ* = 0.38 ± 0.07, i.e., galaxies with denser stars also have steeper slopes. At fixed M * and R eff, γ' depends on redshift, in the sense that galaxies at a lower redshift have steeper slopes (∂γ'/∂z = -0.31 ± 0.10). However, the mean redshift evolution of γ' for an individual galaxy is consistent with zero dγ'/dz = -0.10 ± 0.12. This result is obtained by combining our measured dependencies of γ' on z, M *,R eff with the evolution of the R eff-M * taken from the literature, and is broadly consistent with current models of the formation and evolution of massive early-type galaxies. Detailed quantitative comparisons of our results with theory will provide qualitatively new information on the detailed physical processes at work.

  17. THE FMOS-COSMOS SURVEY OF STAR-FORMING GALAXIES AT z ∼ 1.6. III. SURVEY DESIGN, PERFORMANCE, AND SAMPLE CHARACTERISTICS

    SciTech Connect

    Silverman, J. D.; Sugiyama, N.; Kashino, D.; Sanders, D.; Zahid, J.; Kewley, L. J.; Chu, J.; Hasinger, G.; Kartaltepe, J. S.; Arimoto, N.; Renzini, A.; Rodighiero, G.; Baronchelli, I.; Daddi, E.; Juneau, S.; Lilly, S. J.; Carollo, C. M.; Capak, P.; Ilbert, O.; and others

    2015-09-15

    We present a spectroscopic survey of galaxies in the COSMOS field using the Fiber Multi-object Spectrograph (FMOS), a near-infrared instrument on the Subaru Telescope. Our survey is specifically designed to detect the Hα emission line that falls within the H-band (1.6–1.8 μm) spectroscopic window from star-forming galaxies with 1.4 < z < 1.7 and M{sub stellar} ≳ 10{sup 10} M{sub ⊙}. With the high multiplex capability of FMOS, it is now feasible to construct samples of over 1000 galaxies having spectroscopic redshifts at epochs that were previously challenging. The high-resolution mode (R ∼ 2600) effectively separates Hα and [N ii]λ6585, thus enabling studies of the gas-phase metallicity and photoionization state of the interstellar medium. The primary aim of our program is to establish how star formation depends on stellar mass and environment, both recognized as drivers of galaxy evolution at lower redshifts. In addition to the main galaxy sample, our target selection places priority on those detected in the far-infrared by Herschel/PACS to assess the level of obscured star formation and investigate, in detail, outliers from the star formation rate (SFR)—stellar mass relation. Galaxies with Hα detections are followed up with FMOS observations at shorter wavelengths using the J-long (1.11–1.35 μm) grating to detect Hβ and [O iii]λ5008 which provides an assessment of the extinction required to measure SFRs not hampered by dust, and an indication of embedded active galactic nuclei. With 460 redshifts measured from 1153 spectra, we assess the performance of the instrument with respect to achieving our goals, discuss inherent biases in the sample, and detail the emission-line properties. Our higher-level data products, including catalogs and spectra, are available to the community.

  18. The FMOS-COSMOS Survey of Star-forming Galaxies at z~1.6. III. Survey Design, Performance, and Sample Characteristics

    NASA Astrophysics Data System (ADS)

    Silverman, J. D.; Kashino, D.; Sanders, D.; Kartaltepe, J. S.; Arimoto, N.; Renzini, A.; Rodighiero, G.; Daddi, E.; Zahid, J.; Nagao, T.; Kewley, L. J.; Lilly, S. J.; Sugiyama, N.; Baronchelli, I.; Capak, P.; Carollo, C. M.; Chu, J.; Hasinger, G.; Ilbert, O.; Juneau, S.; Kajisawa, M.; Koekemoer, A. M.; Kovac, K.; Le Fèvre, O.; Masters, D.; McCracken, H. J.; Onodera, M.; Schulze, A.; Scoville, N.; Strazzullo, V.; Taniguchi, Y.

    2015-09-01

    We present a spectroscopic survey of galaxies in the COSMOS field using the Fiber Multi-object Spectrograph (FMOS), a near-infrared instrument on the Subaru Telescope. Our survey is specifically designed to detect the Hα emission line that falls within the H-band (1.6-1.8 μm) spectroscopic window from star-forming galaxies with 1.4 < z < 1.7 and Mstellar ≳ 1010 M⊙. With the high multiplex capability of FMOS, it is now feasible to construct samples of over 1000 galaxies having spectroscopic redshifts at epochs that were previously challenging. The high-resolution mode (R ˜ 2600) effectively separates Hα and [N ii]λ6585, thus enabling studies of the gas-phase metallicity and photoionization state of the interstellar medium. The primary aim of our program is to establish how star formation depends on stellar mass and environment, both recognized as drivers of galaxy evolution at lower redshifts. In addition to the main galaxy sample, our target selection places priority on those detected in the far-infrared by Herschel/PACS to assess the level of obscured star formation and investigate, in detail, outliers from the star formation rate (SFR)—stellar mass relation. Galaxies with Hα detections are followed up with FMOS observations at shorter wavelengths using the J-long (1.11-1.35 μm) grating to detect Hβ and [O iii]λ5008 which provides an assessment of the extinction required to measure SFRs not hampered by dust, and an indication of embedded active galactic nuclei. With 460 redshifts measured from 1153 spectra, we assess the performance of the instrument with respect to achieving our goals, discuss inherent biases in the sample, and detail the emission-line properties. Our higher-level data products, including catalogs and spectra, are available to the community.

  19. EMISSION-LINE GALAXIES FROM THE HUBBLE SPACE TELESCOPE PROBING EVOLUTION AND REIONIZATION SPECTROSCOPICALLY (PEARS) GRISM SURVEY. II. THE COMPLETE SAMPLE

    SciTech Connect

    Pirzkal, Nor; Rothberg, Barry; Ly, Chun; Grogin, Norman A.; Dahlen, Tomas; Noeske, Kai G.; Bellini, Andrea; Malhotra, Sangeeta; Rhoads, James E.; Cohen, Seth H.; Mechtley, Matthew; Windhorst, Rogier A.; Meurer, Gerhardt R.; Walsh, Jeremy R.; Hathi, Nimish P.; Holwerda, Benne W.; Straughn, Amber N.

    2013-07-20

    We present a full analysis of the Probing Evolution And Reionization Spectroscopically (PEARS) slitess grism spectroscopic data obtained with the Advanced Camera for Surveys on board Hubble Space Telescope. PEARS covers fields within both the Great Observatories Origins Deep Survey (GOODS) North and South fields, making it ideal as a random survey of galaxies, as well as the availability of a wide variety of ancillary observations complemented by the spectroscopic results. Using the PEARS data, we are able to identify star-forming galaxies (SFGs) within the redshift volume 0 < z < 1.5. Star-forming regions in the PEARS survey are pinpointed independently of the host galaxy. This method allows us to detect the presence of multiple emission-line regions (ELRs) within a single galaxy. We identified a total of 1162 H{alpha}, [O III], and/or [O II] emission lines in the PEARS sample of 906 galaxies to a limiting flux of {approx}10{sup -18} erg s{sup -1} cm{sup -2}. The ELRs have also been compared to the properties of the host galaxy, including morphology, luminosity, and mass. From this analysis, we find three key results: (1) the computed line luminosities show evidence of a flattening in the luminosity function with increasing redshift; (2) the star-forming systems show evidence of complex morphologies with star formation occurring predominantly within one effective (half-light) radius. However, the morphologies show no correlation with host stellar mass. (3) Also, the number density of SFGs with M{sub *} {>=} 10{sup 9} M{sub Sun} decreases by an order of magnitude at z {<=} 0.5 relative to the number at 0.5 < z < 0.9, supporting the argument of galaxy downsizing.

  20. A Flux-limited Sample of z ~ 1 Lyα Emitting Galaxies in the Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Barger, A. J.; Cowie, L. L.; Wold, I. G. B.

    2012-04-01

    We describe a method for obtaining a flux-limited sample of Lyα emitters from Galaxy Evolution Explorer (GALEX) grism data. We show that the multiple GALEX grism images can be converted into a three-dimensional (two spatial axes and one wavelength axis) data cube. The wavelength slices may then be treated as narrowband images and searched for emission-line galaxies. For the GALEX NUV grism data, the method provides a Lyα flux-limited sample over the redshift range z = 0.67-1.16. We test the method on the Chandra Deep Field South field, where we find 28 Lyα emitters with faint continuum magnitudes (NUV > 22) that are not present in the GALEX pipeline sample. We measure the completeness by adding artificial emitters and measuring the fraction recovered. We find that we have an 80% completeness above a Lyα flux of 10-15 erg cm-2 s-1. We use the UV spectra and the available X-ray data and optical spectra to estimate the fraction of active galactic nuclei in the selection. We report the first detection of a giant Lyα blob at z < 1, though we find that these objects are much less common at z = 1 than at z = 3. Finally, we compute limits on the z ~ 1 Lyα luminosity function and confirm that there is a dramatic evolution in the luminosity function over the redshift range z = 0-1. Based in part on data obtained from the Multimission Archive at the Space Telescope Science Institute (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non Hubble Space Telescope data is provided by the NASA Office of Space Science via grant NAG5-7584 and by other grants and contracts. This research used the facilities of the Canadian Astronomy Data Centre operated by the National Research Council of Canada with the support of the Canadian Space Agency.

  1. Near-infrared Hubble Space Telescope polarimetry of a complete sample of narrow-line radio galaxies

    NASA Astrophysics Data System (ADS)

    Ramírez, E. A.; Tadhunter, C. N.; Axon, D.; Batcheldor, D.; Packham, C.; Lopez-Rodriguez, E.; Sparks, W.; Young, S.

    2014-10-01

    We present an analysis of 2.05 μm Hubble Space Telescope polarimetric data for a sample of 13 nearby Fanaroff-Riley type II (FRII) 3CR radio sources (0.03 < z < 0.11) that are classified as narrow-line radio galaxies (NLRG) at optical wavelengths. We find that the compact cores of the NLRG in our sample are intrinsically highly polarized in the near-infrared (near-IR) (6 < P2.05 μm < 60 per cent), with the electric vector (E-vector) perpendicular to the radio axis in 54 per cent of the sources. The levels of extinction required to produce near-IR polarization by the dichroic extinction mechanism are consistent with the measured values recently reported in Ramírez et al., provided that this mechanism has its maximum efficiency. This consistency suggests that the nuclear polarization could be due to dichroic extinction. In this case, toroidal magnetic fields that are highly coherent would be required in the circumnuclear tori to align the elongated dust grains responsible for the dichroic extinction. However, it is not entirely possible to rule out other polarization mechanisms (e.g. scattering, synchrotron emission) with our observations at only one near-IR wavelength. Therefore, further polarimetry observations at mid-IR and radio wavelengths will be required to test whether all the near-IR polarization is due to dichroic extinction.

  2. A spectroscopic analysis of a sample of narrow-line Seyfert 1 galaxies selected from the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Cracco, V.; Ciroi, S.; Berton, M.; Di Mille, F.; Foschini, L.; La Mura, G.; Rafanelli, P.

    2016-10-01

    We revisited the spectroscopic characteristics of narrow-line Seyfert 1 galaxies (NLS1s) by analysing a homogeneous sample of 296 NLS1s at redshift between 0.028 and 0.345, extracted from the Sloan Digital Sky Survey (SDSS-DR7) public archive. We confirm that NLS1s are mostly characterized by Balmer lines with Lorentzian profiles, lower black hole masses and higher Eddington ratios than classic broad-line Seyfert 1 (BLS1s), but they also appear to be active galactic nuclei (AGNs) contiguous with BLS1s and sharing with them common properties. Strong Fe II emission does not seem to be a distinctive property of NLS1s, as low values of Fe II/Hβ are equally observed in these AGNs. Our data indicate that Fe II and Ca II kinematics are consistent with the one of Hβ. On the contrary, O I λ8446 seems to be systematically narrower and it is likely emitted by gas of the broad-line region more distant from the ionizing source and showing different physical properties. Finally, almost all NLS1s of our sample show radial motions of the narrow-line region highly ionized gas. The mechanism responsible for this effect is not yet clear, but there are hints that very fast outflows require high continuum luminosities (>1044 erg s-1) or high Eddington ratios (log (Lbol/LEdd) > -0.1).

  3. Star formation properties in barred galaxies. III. Statistical study of bar-driven secular evolution using a sample of nearby barred spirals

    SciTech Connect

    Zhou, Zhi-Min; Wu, Hong; Cao, Chen E-mail: hwu@bao.ac.cn

    2015-01-01

    Stellar bars are important internal drivers of secular evolution in disk galaxies. Using a sample of nearby spiral galaxies with weak and strong bars, we explore the relationships between the star formation feature and stellar bars in galaxies. We find that galaxies with weak bars tend coincide with low concentrical star formation activity, while those with strong bars show a large scatter in the distribution of star formation activity. We find enhanced star formation activity in bulges toward stronger bars, although not predominantly, consistent with previous studies. Our results suggest that different stages of the secular process and many other factors may contribute to the complexity of the secular evolution. In addition, barred galaxies with intense star formation in bars tend to have active star formation in their bulges and disks, and bulges have higher star formation densities than bars and disks, indicating the evolutionary effects of bars. We then derived a possible criterion to quantify the different stages of the bar-driven physical process, while future work is needed because of the uncertainties.

  4. CARS: The CFHTLS-Archive-Research Survey. III. First detection of cosmic magnification in samples of normal high-z galaxies

    NASA Astrophysics Data System (ADS)

    Hildebrandt, H.; van Waerbeke, L.; Erben, T.

    2009-11-01

    Context: Weak gravitational lensing (WL) has been established as one of the most promising probes of cosmology. So far, most studies have exploited the shear effect of WL leading to coherent distortions of galaxy shapes. WL also introduces coherent magnifications. Aims: We want to detect this cosmic magnification effect (coherent magnification by the large-scale structure of the Universe) in large samples of high-redshift galaxies selected from the Deep part of the Canada-France-Hawaii-Telescope Legacy Survey (CFHTLS). Methods: Lyman-break galaxies (LBGs) selected by their colours to be at z= 2.5-5, are used as a background sample and are cross-correlated to foreground lens galaxies, which are selected by accurate photometric redshifts (photo-z's). The signals of LBGs in different magnitude bins are compared to predictions from WL theory. An optimally weighted correlation function is estimated by taking into account the slope of external LBG luminosity functions. Results: For the first time, we detect cosmic magnification in a sample of normal galaxies. These background sources are also the ones with the highest redshifts so far used for WL measurements. The amplitude and angular dependence of the cross-correlation functions agree well with theoretical expectations and the lensing signal is detected with high significance. Avoiding low-redshift ranges in the foreground samples which might contaminate the LBG samples we can make a measurement that is virtually free of systematics. In particular, we detect an anti-correlation between faint LBGs and foreground galaxies which cannot be caused by redshift overlap. Conclusions: Cross-correlating LBGs (and in future also photo-z selected galaxies) as background sources to well understood foreground samples based on accurate photo-z's will become a powerful cosmological probe in future large imaging surveys. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada

  5. Analysis of galaxy spectral energy distributions from far-UV to far-IR with CIGALE: studying a SINGS test sample

    NASA Astrophysics Data System (ADS)

    Noll, S.; Burgarella, D.; Giovannoli, E.; Buat, V.; Marcillac, D.; Muñoz-Mateos, J. C.

    2009-12-01

    Aims: Photometric data of galaxies covering the rest-frame wavelength range from far-UV to far-IR make it possible to derive galaxy properties with a high reliability by fitting the attenuated stellar emission and the related dust emission at the same time. Methods: For this purpose we wrote the code CIGALE (Code Investigating GALaxy Emission) that uses model spectra composed of the Maraston (or PEGASE) stellar population models, synthetic attenuation functions based on a modified Calzetti law, spectral line templates, the Dale & Helou dust emission models, and optional spectral templates of obscured AGN. Depending on the input redshifts, filter fluxes were computed for the model set and compared to the galaxy photometry by carrying out a Bayesian-like analysis. CIGALE was tested by analysing 39 nearby galaxies selected from SINGS. The reliability of the different model parameters was evaluated by studying the resulting expectation values and their standard deviations in relation to the input model grid. Moreover, the influence of the filter set and the quality of photometric data on the code results was estimated. Results: For up to 17 filters with effective wavelengths between 0.15 and 160 μm, we find robust results for the mass, star formation rate, effective age of the stellar population at 4000 Å, bolometric luminosity, luminosity absorbed by dust, and attenuation in the far-UV. Details of the star formation history (excepting the burst fraction) and the shape of the attenuation curve are difficult to investigate with the available broad-band UV and optical photometric data. A study of the mutual relations between the reliable properties confirms the dependence of star formation activity on morphology in the local Universe and indicates a significant drop in this activity at about 1011 M⊙ towards higher total stellar masses. The dustiest galaxies in the SINGS sample are present in the same mass range. On the other hand, the far-UV attenuation of our sample

  6. The Sizes of Candidate z˜9-10 Galaxies: Confirmation of the Bright CANDELS Sample and Relation with Luminosity and Mass.

    NASA Astrophysics Data System (ADS)

    Holwerda, B. W.; Bouwens, R.; Oesch, P.; Smit, R.; Illingworth, G.; Labbe, I.

    2015-07-01

    Recently, a small sample of six z ˜ 9-10 candidates was discovered in CANDELS that are ˜ 10-20× more luminous than any of the previous z ˜ 9-10 galaxies identified over the HUDF/XDF and CLASH fields. We measure the sizes of these candidates to map out the size evolution of galaxies from the earliest observable times. Their sizes are also used to provide a valuable constraint on whether these unusual galaxy candidates are at high redshift. Using galfit to derive sizes from the CANDELS F160W images of these candidates, we find a mean size of 0\\buildrel{\\prime\\prime}\\over{.} 13+/- 0\\buildrel{\\prime\\prime}\\over{.} 02 (or 0.5 ± 0.1 kpc at z ˜ 9-10). This handsomely matches the 0.6 kpc size expected extrapolating lower-redshift measurements to z ˜ 9-10, while being much smaller than the 0.″59 mean size for lower-redshift interlopers to z ˜ 9-10 photometric selections lacking the blue IRAC color criterion. This suggests that source size may be an effective constraint on contaminants from z ˜ 9-10 selections lacking IRAC data. Assuming on the basis of the strong photometric evidence that the Oesch et al. sample is entirely at z ˜ 9-10, we can use this sample to extend current constraints on the size-luminosity, size-mass relation, and size evolution of galaxies to z˜ 10. We find that the z ˜ 9-10 candidate galaxies have broadly similar sizes and luminosities as z˜ 6-8 counterparts with star formation rate surface densities in the range of {{{Σ }}}{SFR}=1-20 {M}⊙ {{yr}}-1 {{kpc}}-2. The stellar mass-size relation is uncertain, but shallower than those inferred for lower-redshift galaxies. In combination with previous size measurements at z = 4-7, we find a size evolution of {(1+z)}-m with m=1.0+/- 0.1 for \\gt 0.3L{*}z=3 galaxies, consistent with the evolution previously derived from 2\\lt z\\lt 8 galaxies.

  7. X-ray emission from a complete sample of Abell clusters of galaxies

    NASA Technical Reports Server (NTRS)

    Briel, Ulrich G.; Henry, J. Patrick

    1993-01-01

    The Rosat all sky survey is used to investigate the X-ray properties of a sample of Abell clusters with measured redshifts and accurate positions. The sample comprises the 145 clusters within a 561 square degree region at high galactic latitude. The mean redshift is 0.17. The sample mean exposure time is higher than average and its mean galactic column density is very low. These together produce a flux limit of about 4.2 x 10(exp -13) erg/sq cm/s in the 0.5 to 2.5 keV energy band. By analyzing the excess of positive fluctuations of the X-ray flux at the cluster positions, compared with the fluctuations of randomly drawn background fields, it is possible to extend these results below the nominal flux limit. It is found that 80 of richness R equal to or greater than 0 and 86 of R equal to or greater than 1 clusters are X-ray emitters with fluxes above 1.10 to the power of minus 13 erg/sq cm/s. Nearly 90 of the clusters meeting the requirements to be in Abell's statistical sample emit above the same level. It is concluded that almost all Abell clusters are real clusters and the Abell catalogue is not strongly contaminated by projection effects. The Kaplan-Meier product limit estimator is used to calculate the cumulative X-ray luminosity function. It is shown that the shape of the luminosity functions are similar for different richness classes, but the characteristic luminosities of richness 2 clusters are about twice of those of richness 1 clusters which are in turn about twice of those of richness zero clusters. This result is another manifestation of the luminosity richness relation for Abell cluster.

  8. Structure and photometry of an I less than 20.5 galaxy sample from the Hubble Space Telescope medium deep survey

    NASA Astrophysics Data System (ADS)

    Phillips, Andrew C.; Bershady, Matthew A.; Forbes, Duncan A.; Koo, David C.; Illingworth, Garth D.; Reitzel, David B.; Griffiths, Richard E.; Windhorst, Rogier A.

    1995-05-01

    A set of 100 faint galaxies from nine Hubble Space Telescope (HST) Wide Field Camera (WFC) I-band images have been analyzed as part of the Medium Deep Survey (MDS) Key Project. This sample reaches a depth of I approximately less than or equal to 20.5 (corresponding to B approximately 22-23) and complements the first set of fainter galaxies analyzed by the MDS team. Images were deconvolved using the Lucy-Richardson algorithm and a newly developed procedure designed to yield a more reliable determination of structure in the low-S/N regime. These deconvolved images were used to characterize the structure of the galaxies through quantative measurements of total magnitudes, half-light radii, exponential disk scale lengths, and disk-to-total rations. Extensive testing was done to establish the validity of the procedures used and to characterize the degree of systematic errors present in the analysis techniques. The observed size-magnitude distribution appears consistent with a scenario in which luminous galaxies have evolved little in intrinsic luminosity, size, or structure over recent epochs in a 'normal' cosmology (0 less than q0 less than 0.5 and Lambda0 = 0). The predicted nonevolving distributions were based on models designed to fit existing counts, colors, and redshifts of faint galaxies and on the observed correlations between metric rest-frame size and luminosity found in a nearby galaxy sample studied by Kent (1984-1985). The typical galaxy in our sample is expected to be at z approximately equal to 0.3, and to have a luminosity approximately 0.5 mag fainter than L* and a half-light radius of approximately 1 sec or approximately 6 kpc (H 0 = 50 km/s Mpc). The observed distribution of disk-to-total ratios, while uncertain, is in agreement with that of Kent's sample and thus supports the view that substantial evolution has not occurred over the look-back times characteristic of our sample.

  9. MULTI-WAVELENGTH OBSERVATIONS OF A SAMPLE OF INTERMEDIATE-LUMINOSITY RADIO-LOUD ACTIVE GALAXIES

    SciTech Connect

    Lewis, Karen T.; Sambruna, Rita M.; Cheung, Chi C.; Eracleous, Michael; Kadler, Matthias

    2011-07-15

    We present the results from exploratory (12-23 ks) XMM-Newton observations of six optically selected, radio-loud active galactic nuclei (AGNs), together with new radio data and a reanalysis of their archival SDSS spectra. The sources were selected in an effort to expand the current sample of radio-loud AGNs suitable for detailed X-ray spectroscopy studies. The sample includes three broad-line and three narrow-line sources, with X-ray luminosities of the order of L{sub 2-10keV} {approx} 10{sup 43} erg s{sup -1}. The EPIC spectra of the broad-lined sources can be described by single power laws with photon indices {Gamma} {approx} 1.6 and little to negligible absorption (N{sub H} {approx}<10{sup 21} cm{sup -2}); on the contrary, significant absorption is detected in the narrow-lined objects, N{sub H} {approx} 10{sup 23} cm{sup -2}, one of which displays a prominent (equivalent width {approx}2 keV) Fe K{alpha} emission line. Studying their location in several luminosity-luminosity diagrams for radio-loud AGNs, we find that the sources fall at the lower end of the distribution for bright, classical radio-loud AGNs and close to LINER-like sources. As such, and as indicated by the ratios of their optical emission lines, we conclude that the sources of our sample fall on the border between radiatively efficient and inefficient accretion flows. Future deeper studies of these targets at X-rays and longer wavelengths will expand our understanding of the central engines of radio-loud AGNs at a critical transition region.

  10. Evidence for ubiquitous high-equivalent-width nebular emission in z ∼ 7 galaxies: toward a clean measurement of the specific star-formation rate using a sample of bright, magnified galaxies

    SciTech Connect

    Smit, R.; Bouwens, R. J.; Labbé, I.; Zheng, W.; Lemze, D.; Ford, H.; Bradley, L.; Coe, D.; Postman, M.; Donahue, M.; Moustakas, J.; Umetsu, K.; Zitrin, A.; Bartelmann, M.; Gonzalez, V.; Benítez, N.; Jimenez-Teja, Y.; Grillo, C.; Infante, L.; and others

    2014-03-20

    Growing observational evidence indicates that nebular line emission has a significant impact on the rest-frame optical fluxes of z ∼ 5-7 galaxies. This line emission makes z ∼ 5-7 galaxies appear more massive, with lower specific star-formation rates (sSFRs). However, corrections for this line emission have been difficult to perform reliably because of huge uncertainties on the strength of such emission at z ≳ 5.5. In this paper, we present the most direct observational evidence thus far for ubiquitous high-equivalent-width (EW) [O III] + Hβ line emission in Lyman-break galaxies at z ∼ 7, and we present a strategy for an improved measurement of the sSFR at z ∼ 7. We accomplish this through the selection of bright galaxies in the narrow redshift window z ∼ 6.6-7.0 where the Spitzer/Infrared Array Camera (IRAC) 4.5 μm flux provides a clean measurement of the stellar continuum light, in contrast with the 3.6 μm flux, which is contaminated by the prominent [O III] + Hβ lines. To ensure a high signal-to-noise ratio for our IRAC flux measurements, we consider only the brightest (H {sub 160} < 26 mag) magnified galaxies we have identified behind galaxy clusters. It is remarkable that the mean rest-frame optical color for our bright seven-source sample is very blue, [3.6]-[4.5] = –0.9 ± 0.3. Such blue colors cannot be explained by the stellar continuum light and require that the rest-frame EW of [O III] + Hβ is greater than 637 Å for the average source. The four bluest sources from our seven-source sample require an even more extreme EW of 1582 Å. We can also set a robust lower limit of ≳ 4 Gyr{sup –1} on the sSFR of our sample based on the mean spectral energy distribution.

  11. A statistically selected Chandra sample of 20 galaxy clusters - II. Gas properties and cool core/non-cool core bimodality

    NASA Astrophysics Data System (ADS)

    Sanderson, Alastair J. R.; O'Sullivan, Ewan; Ponman, Trevor J.

    2009-05-01

    We investigate the thermodynamic and chemical structure of the intracluster medium (ICM) across a statistical sample of 20 galaxy clusters analysed with the Chandra X-ray satellite. In particular, we focus on the scaling properties of the gas density, metallicity and entropy and the comparison between clusters with and without cool cores (CCs). We find marked differences between the two categories except for the gas metallicity, which declines strongly with radius for all clusters (Z ~ r-0.31), outside ~0.02r500. The scaling of gas entropy is non-self-similar and we find clear evidence of bimodality in the distribution of logarithmic slopes of the entropy profiles. With only one exception, the steeper sloped entropy profiles are found in CC clusters whereas the flatter slope population are all non-CC clusters. We explore the role of thermal conduction in stabilizing the ICM and conclude that this mechanism alone is sufficient to balance cooling in non-CC clusters. However, CC clusters appear to form a distinct population in which heating from feedback is required in addition to conduction. Under the assumption that non-CC clusters are thermally stabilized by conduction alone, we find the distribution of Spitzer conduction suppression factors, fc, to be lognormal, with a log (base 10) mean of -1.50 +/- 0.03 (i.e. fc = 0.032) and log standard deviation 0.39 +/- 0.02.

  12. Warm Absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert galaxies

    NASA Astrophysics Data System (ADS)

    Laha, S.; Guainazzi, M.; Dewangan, G.; Chakravorty, S.; Kembhavi, A.

    2014-07-01

    We present results from a homogeneous analysis of the broadband 0.3-10 keV CCD resolution as well as of soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. We could put a strict lower limit on the detection fraction of 50%. We find a gap in the distribution of the ionisation parameter in the range 0.5

  13. H I emission and absorption in nearby, gas-rich galaxies - II. Sample completion and detection of intervening absorption in NGC 5156

    NASA Astrophysics Data System (ADS)

    Reeves, S. N.; Sadler, E. M.; Allison, J. R.; Koribalski, B. S.; Curran, S. J.; Pracy, M. B.; Phillips, C. J.; Bignall, H. E.; Reynolds, C.

    2016-04-01

    We present the results of a survey for intervening 21 cm H I absorption in a sample of 10 nearby, gas-rich galaxies selected from the H I Parkes All-Sky Survey (HIPASS). This follows the six HIPASS galaxies searched in previous work and completes our full sample. In this paper, we searched for absorption along 17 sightlines with impact parameters between 6 and 46 kpc, making one new detection. We also obtained simultaneous H I emission-line data, allowing us to directly relate the absorption-line detection rate to the H I distribution. From this, we find the majority of the non-detections in the current sample are because sightline does not intersect the H I disc of the galaxy at sufficiently high column density, but that source structure is also an important factor. The detected absorption-line arises in the galaxy NGC 5156 (z = 0.01) at an impact parameter of 19 kpc. The line is deep and narrow with an integrated optical depth of 0.82 km s-1. High-resolution Australia Telescope Compact Array (ATCA) images at 5 and 8 GHz reveal that the background source is resolved into two components with a separation of 2.6 arcsec (500 pc at the redshift of the galaxy), with the absorption likely occurring against a single component. We estimate that the ratio of the spin temperature and covering factor, TS/f, is approximately 950 K in the outer disc of NGC 5156, but further observations using very long baseline interferometry would allow us to accurately measure the covering factor and spin temperature of the gas.

  14. OT2_eibar_1: A detailed anaysis of the [CII] line emission for a large sample of star-forming galaxies at z<0.2

    NASA Astrophysics Data System (ADS)

    Ibar, E.

    2011-09-01

    We propose to exploit the spectroscopic capabilities of PACS to describe the [C II] line emission in a unique and comprehensive sample of star-forming galaxies selected from the wide-field, parallel PACS+SPIRE H-ATLAS imaging survey. The sample has exquisite optical spectra from GAMA and SDSS, allowing us to: [1] describe [C II] line as a function of dust and stellar mass, metallicity, extinction, dust temperature, and many other physical parameters; [2] identify the parameters controlling the behaviour of [CII]/L(FIR) at log L(FIR)>11; [3] calibrate [CII] as a star-formation indicator [exploiting our accurate L(FIR) and L(Halpha)] and determine the range over which it is valid. [CII] is potentially an unrivalled tracer of the total gas mass in galaxies (in theory better than CO), and it is therefore an increasingly important observable, e.g. for upcoming ALMA observations of distant galaxies. Our study will become the benchmark for the interpretation of high-z observations, with a legacy value that will survive well into the SPICA era. Some of the key advantages of this proposal over previous Herschel studies such as SHINING and HerCULES are: - we cover 10.2 < log L(FIR) < 11.5 and are unbiased towards powerful ULIRGs with complex merger morphologies; - our sample is selected blindly from H-ATLAS rather than from IRAS, and thus allows exploration of comprehensive parameter space and is much less biased towards galaxies with warm dust emission; - we know the spatial extent of the galaxies, allowing reliable flux measurements via a single pointing within 10 min/target. We can thus achieve our goals in a systematic fashion, maximising the parameter space for the diagnostics of interest. We stress that the scientific legacy of ISO and Spitzer has in large part been based on the wealth of data in their spectroscopic archives and the same will likely be true for Herschel.

  15. REDSHIFTS, SAMPLE PURITY, AND BCG POSITIONS FOR THE GALAXY CLUSTER CATALOG FROM THE FIRST 720 SQUARE DEGREES OF THE SOUTH POLE TELESCOPE SURVEY

    SciTech Connect

    Song, J.; Zenteno, A.; Desai, S.; Bazin, G.; Stalder, B.; Ashby, M. L. N.; Bayliss, M.; Bleem, L. E.; Benson, B. A.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T.; Aird, K. A.; Armstrong, R.; Bertin, E.; Brodwin, M.; Cho, H. M.; Clocchiatti, A.; De Haan, T.; and others

    2012-12-10

    We present the results of the ground- and space-based optical and near-infrared (NIR) follow-up of 224 galaxy cluster candidates detected with the Sunyaev-Zel'dovich (SZ) effect in the 720 deg{sup 2} of the South Pole Telescope (SPT) survey completed in the 2008 and 2009 observing seasons. We use the optical/NIR data to establish whether each candidate is associated with an overdensity of galaxies and to estimate the cluster redshift. Most photometric redshifts are derived through a combination of three different cluster redshift estimators using red-sequence galaxies, resulting in an accuracy of {Delta}z/(1 + z) = 0.017, determined through comparison with a subsample of 57 clusters for which we have spectroscopic redshifts. We successfully measure redshifts for 158 systems and present redshift lower limits for the remaining candidates. The redshift distribution of the confirmed clusters extends to z = 1.35 with a median of z{sub med} = 0.57. Approximately 18% of the sample with measured redshifts lies at z > 0.8. We estimate a lower limit to the purity of this SPT SZ-selected sample by assuming that all unconfirmed clusters are noise fluctuations in the SPT data. We show that the cumulative purity at detection significance {xi} > 5({xi} > 4.5) is {>=}95% ({>=}70%). We present the red brightest cluster galaxy (rBCG) positions for the sample and examine the offsets between the SPT candidate position and the rBCG. The radial distribution of offsets is similar to that seen in X-ray-selected cluster samples, providing no evidence that SZ-selected cluster samples include a different fraction of recent mergers from X-ray-selected cluster samples.

  16. (Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. III. Environments

    NASA Astrophysics Data System (ADS)

    Smolčić, V.; Miettinen, O.; Tomičić, N.; Zamorani, G.; Finoguenov, A.; Lemaux, B. C.; Aravena, M.; Capak, P.; Chiang, Y.-K.; Civano, F.; Delvecchio, I.; Ilbert, O.; Jurlin, N.; Karim, A.; Laigle, C.; Le Fèvre, O.; Marchesi, S.; McCracken, H. J.; Riechers, D. A.; Salvato, M.; Schinnerer, E.; Tasca, L.; Toft, S.

    2017-01-01

    We investigate the environment of 23 submillimetre galaxies (SMGs) drawn from a signal-to-noise (S/N)-limited sample of SMGs originally discovered in the James Clerk Maxwell Telescope (JCMT)/AzTEC 1.1 mm continuum survey of a Cosmic Evolution Survey (COSMOS) subfield and then followed up with the Submillimetre Array and Plateau de Bure Interferometer at 890 μm and 1.3 mm, respectively. These SMGs already have well-defined multiwavelength counterparts and redshifts. We also analyse the environments of four COSMOS SMGs spectroscopically confirmed to lie at redshifts zspec > 4.5, and one at zspec = 2.49 resulting in a total SMG sample size of 28. We search for overdensities using the COSMOS photometric redshifts based on over 30 UV-NIR photometric measurements including the new UltraVISTA data release 2 and Spitzer/SPLASH data, and reaching an accuracy of σΔz/ (1 + z) = 0.0067 (0.0155) at z < 3.5 (>3.5). To identify overdensities we apply the Voronoi tessellation analysis, and estimate the redshift-space overdensity estimator δg as a function of distance from the SMG and/or overdensity centre. We test and validate our approach via simulations, X-ray detected groups or clusters, and spectroscopic verifications using VUDS and zCOSMOS catalogues which show that even with photometric redshifts in the COSMOS field we can efficiently retrieve overdensities out to z ≈ 5. Our results yield that 11 out of 23 (48%) JCMT/AzTEC 1.1 mm SMGs occupy overdense environments. Considering the entire JCMT/AzTEC 1.1 mm S/N ≥ 4 sample and taking the expected fraction of spurious detections into account, this means that 35-61% of the SMGs in the S/N-limited sample occupy overdense environments. We perform an X-ray stacking analysis in the 0.5-2 keV band using a 32″ aperture and our SMG positions, and find statistically significant detections. For our z < 2 subsample we find an average flux of (4.0 ± 0.8) × 10-16 erg s-1 cm-2 and a corresponding total mass of M200 = 2.8 × 1013M

  17. The MOJAVE Chandra Sample: A Correlation Study of Blazars and Radio Galaxies in X-ray and Radio Wavelengths

    NASA Astrophysics Data System (ADS)

    Hogan, Brandon Scott

    2011-05-01

    The Chandra X-ray observatory has increased the quality and number of detections the X-ray regime since its launch in 1999. It is an important tool for studying the jets which are associated with Active Galactic Nuclei (AGN) and their possible emission mechanisms. The MOJAVE Chandra Sample (MCS) is a sample of 27 AGN which have been selected from the radio flux-limited MOJAVE (Monitoring of Jets in AGN with VLBA Experiments) sample. The objects contained in the MOJAVE sample are traditionally associated with relativistically beamed jets that have small viewing angles. The MCS was created to study the correlation of X-ray and radio emission on kiloparsec scales. The complete sample is made up of all MOJAVE Fanaroff & Riley type II objects which have over 100 mJy of extended radio emission at 1.4 GHz and a radio structure of at least 3" in extent. Chandra observations have revealed X-ray and radio correlation in 21 of the 27 jets, bringing the detection rate to ˜78%. The selection criteria provides a quantitative method of discovering new X-ray jets associated with AGN from radio observations. The X-ray morphologies are usually well correlated with the radio emission, except for the sources which show extreme bending on the kiloparsec scale. The emission mechanism for these relativistically beamed quasars and radio galaxies can be interpreted as inverse Compton scattering off of the cosmic microwave background by the electrons in the jets (IC/CMB). The emission mechanism is reinforced by spectral energy distributions (SED) which model the emission mechanisms for sources with sufficient X-ray, optical, and radio data available. I have explored the effects of jet bending and jet deceleration in conjunction with the inverse Compton emission model and used different scenarios to derive best fit viewing angles and bulk Lorentz factors, which were calculated by using the superluminal speeds along with parameters that were derived from the IC/CMB model. The range of

  18. [C II] 158-micrometer Observations of a Sample of Late-type Galaxies from the Virgo Cluster

    NASA Technical Reports Server (NTRS)

    Leech, K. J.; Volk, H. J.; Heinrichsen, I.; Hippelein, H.; Metcalfe, L.; Pierini, D.; Popescu, C. C.; Tuffs, R. J.; Xu, C.

    1998-01-01

    We have observed 19 Virgo cluster spiral galaxies with the Long Wavelength Spectrometer (LWS) onboard ESAs Infrared Space Observatory (ISO) obtaining spectral around the (C II) 157.741-micrometer fine structure line.

  19. A robust sample of galaxies at redshifts 6.0

    NASA Astrophysics Data System (ADS)

    McLure, R. J.; Dunlop, J. S.; de Ravel, L.; Cirasuolo, M.; Ellis, R. S.; Schenker, M.; Robertson, B. E.; Koekemoer, A. M.; Stark, D. P.; Bowler, R. A. A.

    2011-12-01

    We present the results of a photometric redshift analysis designed to identify z≥ 6 galaxies from the near-infrared Hubble Space Telescope imaging in three deep fields [Hubble Ultra Deep Field (HUDF), HUDF09-2 and Early Release Science] covering a total area of 45 square arcmin. By adopting a rigorous set of criteria for rejecting low-redshift interlopers, and by employing a deconfusion technique to allow the available ultradeep IRAC imaging to be included in the candidate-selection process, we have derived a robust sample of 70 Lyman break galaxies (LBGs) spanning the redshift range 6.0 < z < 8.7. Based on our final sample, we investigate the distribution of ultraviolet (UV) spectral slopes (fλ∝λβ), finding a variance-weighted mean value of <β>=-2.05 ± 0.09 which, contrary to some previous results, is not significantly bluer than displayed by lower redshift starburst galaxies. We confirm the correlation between UV luminosity and stellar mass reported elsewhere, but based on fitting galaxy templates featuring a range of star formation histories (SFHs), metallicities and reddening, we find that, at z≥ 6, the range in mass-to-light ratio (M★/LUV) at a given UV luminosity could span a factor of ≃50. Focusing on a subsample of 21 candidates with IRAC detections at ?m, we find that L★ LBGs at z≃ 6.5 have a median stellar mass of M★= (2.1 ± 1.1) × 109 M⊙ (Chabrier initial mass function) and a median specific star formation rate (sSFR) of 1.9 ± 0.8 Gyr-1. Using the same subsample, we have investigated the influence of nebular continuum and line emission, finding that for the majority of candidates (16 out of 21), the best-fitting stellar masses are reduced by less than a factor of 2.5. However, galaxy template fits exploring a plausible range of SFHs and metallicities provide no compelling evidence of a clear connection between SFR and stellar mass at these redshifts. Finally, a detailed comparison of our final sample with the results of previous

  20. Kinematic analysis of a sample of X-ray luminous distant galaxy clusters. The LX - σv relation in the z > 0.6 universe

    NASA Astrophysics Data System (ADS)

    Nastasi, A.; Böhringer, H.; Fassbender, R.; de Hoon, A.; Lamer, G.; Mohr, J. J.; Padilla, N.; Pratt, G. W.; Quintana, H.; Rosati, P.; Santos, J. S.; Schwope, A. D.; Šuhada, R.; Verdugo, M.

    2014-04-01

    Aims: Observations and cosmological simulations show galaxy clusters as a family of nearly self-similar objects with properties that can be described by scaling relations as a function of mass and time. Here we study the scaling relations between the galaxy velocity dispersion (σv) and X-ray quantities, such as X-ray bolometric luminosity (LBolX,500) and temperature (TX) in galaxy clusters at high redshifts (0.64 ≤ z ≤ 1.46). We also compare our results with the analogous study of the local HIFLUGCS sample. Methods: For the analysis, we use a set of 15 distant galaxy clusters extracted from the literature and selected via different methods. We also use a sample of ten newly discovered clusters selected via their X-ray emission by the XMM-Newton Distant Cluster Project (XDCP), with more than ten confirmed spectroscopic members per cluster. For both samples, the same method was used to determine σv. We also study the evolution of this scaling relation by comparing the high redshift results with the data from the HIFLUGCS sample, which is taken as a representative of the conditions in the local Universe. For such an analysis, we restrict the study to the clusters in the common LBolX,500 range. We also investigate the LX - TX and the σv - TX relations for the 15 clusters from the literature sample. Results: We report the results of the X-ray and kinematic analysis of ten newly detected high redshift clusters and provide their spectroscopic and kinematic details. For the entire distant sample, we find a slope fully consistent with the one typical of local clusters, albeit with a large associated uncertainty (~26%). We repeat the fit by freezing the slope to the value found for the HIFLUGCS systems restricted to the same luminosity range as our sample to investigate the evolution of the amplitude alone. We find a positive offset of ΔA/A = 0.44 ± 0.22 if the self-similar evolution is neglected, hence indicating the possible need for including evolutionary effects

  1. Boosting Lyα and He II λ1640 Line Fluxes from Population III Galaxies: Stochastic IMF Sampling and Departures from Case-B

    NASA Astrophysics Data System (ADS)

    Mas-Ribas, Lluís; Dijkstra, Mark; Forero-Romero, Jaime E.

    2016-12-01

    We revisit calculations of nebular hydrogen Lyα and He ii λ1640 line strengths for Population III (Pop III) galaxies, undergoing continuous, and bursts of, star formation. We focus on initial mass functions (IMFs) motivated by recent theoretical studies, which generally span a lower range of stellar masses than earlier works. We also account for case-B departures and the stochastic sampling of the IMF. In agreement with previous work, we find that departures from case-B can enhance the Lyα flux by a factor of a few, but we argue that this enhancement is driven mainly by collisional excitation and ionization, and not due to photoionization from the n = 2 state of atomic hydrogen. The increased sensitivity of the Lyα flux to the high-energy end of the galaxy spectrum makes it more subject to stochastic sampling of the IMF. The latter introduces a dispersion in the predicted nebular line fluxes around the deterministic value by as much as a factor of ∼4. In contrast, the stochastic sampling of the IMF has less impact on the emerging Lyman Werner photon flux. When case-B departures and stochasticity effects are combined, nebular line emission from Pop III galaxies can be up to one order of magnitude brighter than predicted by “standard” calculations that do not include these effects. This enhances the prospects for detection with future facilities such as the James Webb Space Telescope and large, ground-based telescopes.

  2. NEWFIRM Medium-Band Survey + Herschel PACS-SPIRE: Constraining the Infrared Properties of a Mass-Complete Sample of 5000 Galaxies at 1

    NASA Astrophysics Data System (ADS)

    Marchesini, Danilo

    Understanding the formation mechanisms and evolution with cosmic time of massive galaxies is one of the key unsolved problems in astrophysics. At the endpoint of the hierarchical merging process, massive galaxies are most sensitive to various model assumptions, offering a strong opportunity to constrain models of galaxy formation. For the first time, the NEWFIRM Medium-band Survey (NMBS) made it possible to construct mass-complete samples of massive galaxies with accurate photometric redshifts at 1 < z < 4. Recent measurements show a dramatic evolution of the stellar mass function of galaxies with redshift and evidence of mass-dependent evolution. Moreover, it has become established that a substantial fraction of the massive quiescent galaxies that dominate the red-sequence at z=0 are already in place at z~2.3. The rapid assembly and quiescent nature of this population, and the remarkable lack of evolution in the number density of massive galaxies seems inconsistent with predictions from models of galaxy formation. To further our understanding of the evolution of massive galaxies, detailed characterization of the infrared (IR) spectral energy distributions (SEDs) and emission from dust, and accurate estimates of (dust-obscured) star-formation rates (SFRs) and AGN contribution are needed for a large, complete sample of massive galaxies with accurate redshifts at z>1. We propose to augment the well-sampled UV-to-MIPS SEDs delivered by the NMBS with the photometry from Herschel PACS and SPIRE (100, 160, 250, 350, and 500 micron). The NMBS uses a set of five medium-bandwidth NIR filters to provide very precise photometric redshifts and well-sampled SEDs at z>1.5. The public NMBS catalogs consist of about 60,000 objects at z<4 with photometry in the UV (GALEX), optical, NIR (broad- and medium-band filters), and mid-IR (Spitzer). The proposed program will extend the NMBS SEDs into the IR (100-500 micron). The construction and public release of the combined NMBS

  3. New insights to the photometric structure of Blue Compact Dwarf Galaxies from deep near-infrared studies. II. The sample of northern BCDs

    NASA Astrophysics Data System (ADS)

    Noeske, K. G.; Papaderos, P.; Cairós, L. M.; Fricke, K. J.

    2005-01-01

    This paper is part of a series of publications which present a systematic study of Blue Compact Dwarf (BCD) Galaxies in the near infrared (NIR). Compared to the visible light, NIR data allow a better separation of the starburst emission from the light distribution of the old stellar low-surface brightness (LSB) host galaxy. We analyze deep NIR broad band images of a sample of 11 BCDs, observed with the Calar Alto 3.6 m telescope. This work enlarges the samples presented in preceding papers of this study (Noeske et al. \\cite{Noeske2003}, A&A, 410, 481; Cairós et al. \\cite{c03a}, ApJ, 593, 312) by BCDs of the most common morphological type, displaying a regular elliptical LSB host galaxy. The data presented here allow the detection and quantitative study of the extended stellar LSB host galaxy in all sample BCDs. The NIR surface brightness profiles (SBPs) of the LSB host galaxies agree at large galactocentric radii with those from optical studies, showing also an exponential intensity decrease and compatible scale lengths. Similar to Noeske et al. (\\cite{Noeske2003}), we find centrally flattening exponential (type V) SBPs of the host galaxy for several BCDs. Such SBPs remain mostly undetected in optical bands, due to the comparatively stronger starburst emission at these wavelengths. We apply a modified exponential distribution to decompose and quantitatively analyze SBPs of LSB hosts with a type V intensity distribution. We present the results of the surface photometry and the decomposition of SBPs, and discuss individual objects with respect to morphological details of their star-forming regions. Table 2 is also available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http:/ /cdsweb.u-strasbg.fr/ cgi-bin/ qcat?J/A+A/429/115 Figures 2 to 11 are only available in electronic form at http://www.edpsciences.org German-Spanish Astronomical Center, Calar Alto, operated by the Max-Planck-Institute for Astronomy, Heidelberg

  4. HIghMass-High H I Mass, H I-rich Galaxies at z ~ 0 Sample Definition, Optical and Hα Imaging, and Star Formation Properties

    NASA Astrophysics Data System (ADS)

    Huang, Shan; Haynes, Martha P.; Giovanelli, Riccardo; Hallenbeck, Gregory; Jones, Michael G.; Adams, Elizabeth A. K.; Brinchmann, Jarle; Chengalur, Jayaram N.; Hunt, Leslie K.; Masters, Karen L.; Matsushita, Satoki; Saintonge, Amelie; Spekkens, Kristine

    2014-09-01

    We present first results of the study of a set of exceptional H I sources identified in the 40% ALFALFA extragalactic H I survey catalog α.40 as both being H I massive (MH \\scriptsize{I} \\gt 1010 M_⊙) and having high gas fractions for their stellar masses: the HIghMass galaxy sample. We analyze UV- and optical-broadband and Hα images to understand the nature of their relatively underluminous disks in optical and to test whether their high gas fractions can be tracked to higher dark matter halo spin parameters or late gas accretion. Estimates of their star formation rates (SFRs) based on spectral energy distribution fitting agree within uncertainties with the Hα luminosity inferred current massive SFRs. The H II region luminosity functions, parameterized as dN/dlog LvpropL α, have standard slopes at the luminous end (α ~ -1). The global SFRs demonstrate that the HIghMass galaxies exhibit active ongoing star formation (SF) with moderate SF efficiency but, relative to normal spirals, a lower integrated SFR in the past. Because the SF activity in these systems is spread throughout their extended disks, they have overall lower SFR surface densities and lower surface brightness in the optical bands. Relative to normal disk galaxies, the majority of HIghMass galaxies have higher Hα equivalent widths and are bluer in their outer disks, implying an inside-out disk growth scenario. Downbending double exponential disks are more frequent than upbending disks among the gas-rich galaxies, suggesting that SF thresholds exist in the downbending disks, probably as a result of concentrated gas distribution.

  5. Andromeda Galaxy

    NASA Image and Video Library

    2003-12-10

    This image is from NASA Galaxy Evolution Explorer is an observation of the large galaxy in Andromeda, Messier 31. The Andromeda galaxy is the most massive in the local group of galaxies that includes our Milky Way.

  6. Modelling the narrow-line regions of active galaxies in the Sloan Digital Sky Survey - I. Sample selection and physical conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Z. T.; Liang, Y. C.; Hammer, F.

    2013-04-01

    Using spectroscopy from the Sloan Digital Sky Survey Data Release Seven, we systematically determine the electron density ne and electron temperature Te of active galaxies and star-forming galaxies, while mainly focusing on the narrow-line regions (NLRs). Herein, active galaxies refer to composites, low-ionization narrow emission-line regions (LINERs) and Seyfert galaxies, following the Baldwin-Phillips-Terlevich diagram classifications afforded by the SDSS data. The plasma diagnostics of ne and Te are determined through the I[S II] λ6716/λ6731 and I[O III] λ5007/λ4363 ratios, respectively. By simultaneously determining ne from [S II] and Te from [O III] in our [O III] λ4363 emission sample of 15 019 galaxies, we find two clear sequences: TLINER ≳ Tcomposite > TSeyfert > Tstar-forming and nLINER ≳ nSeyfert > ncomposite > nstar-forming. The typical range of ne in the NLRs of active galactic nuclei (AGNs) is 102 - 3 cm-3. The temperatures in the NLRs range from 1.0 to 2.0 × 104 K for Seyferts, and the ranges are even higher and wider for LINERs and composites. The transitions of ne and Te from the NLRs to the discs are revealed. We also present a comparative study, including stellar mass (M⋆), specific star formation rate (SFR/M⋆) and plasma diagnostic results. We propose that YL ≳ YSY > YC > YSF, where Y is the characteristic present-day star-formation time-scale. One remarkable feature of the Seyferts shown on an M⋆-SFR/M⋆ diagram, which we call the evolutionary pattern of AGNs with high ionization potential, is that the strong [O III] λ4363 Seyferts distribute uniformly with the weak Seyferts, definitely a reverse of the situation for star-forming galaxies. It is a natural and well-known consensus that strong [O III] λ4363 emissions in star-forming galaxies imply young stellar populations and thus low stellar masses. However, in the AGN case, several strong lines of evidence suggest that some supplementary energy source(s) should be

  7. The clustering of the SDSS main galaxy sample - II. Mock galaxy catalogues and a measurement of the growth of structure from redshift space distortions at z = 0.15

    NASA Astrophysics Data System (ADS)

    Howlett, Cullan; Ross, Ashley J.; Samushia, Lado; Percival, Will J.; Manera, Marc

    2015-05-01

    We measure redshift space distortions in the two-point correlation function of a sample of 63 163 spectroscopically identified galaxies with z < 0.2, an epoch where there are currently only limited measurements, from the Sloan Digital Sky Survey Data Release 7 main galaxy sample (MGS). Our sample, which we denote MGS, covers 6813 deg2 with an effective redshift zeff = 0.15 and is described in our companion paper (Paper I), which concentrates on baryon acoustic oscillation (BAO) measurements. In order to validate the fitting methods used in both papers, and derive errors, we create and analyse 1000 mock catalogues using a new algorithm called PICOLA to generate accurate dark matter fields. Haloes are then selected using a friends-of-friends algorithm, and populated with galaxies using a halo-occupation distribution fitted to the data. Using errors derived from these mocks, we fit a model to the monopole and quadrupole moments of the MGS correlation function. If we assume no Alcock-Paczynski (AP) effect (valid at z = 0.15 for any smooth model of the expansion history), we measure the amplitude of the velocity field, fσ8, at z = 0.15 to be 0.49_{-0.14}^{+0.15}. We also measure fσ8 including the AP effect. This latter measurement can be freely combined with recent cosmic microwave background results to constrain the growth index of fluctuations, γ. Assuming a background Λ cold dark matter cosmology and combining with current BAO data, we find γ = 0.64 ± 0.09, which is consistent with the prediction of general relativity (γ ≈ 0.55), though with a slight preference for higher γ and hence models with weaker gravitational interactions.

  8. Radio Galaxies.

    ERIC Educational Resources Information Center

    Downes, Ann

    1986-01-01

    Provides background information on radio galaxies. Topic areas addressed include: what produces the radio emission; radio telescopes; locating radio galaxies; how distances to radio galaxies are found; physics of radio galaxies; computer simulations of radio galaxies; and the evolution of radio galaxies with cosmic time. (JN)

  9. Radio Galaxies.

    ERIC Educational Resources Information Center

    Downes, Ann

    1986-01-01

    Provides background information on radio galaxies. Topic areas addressed include: what produces the radio emission; radio telescopes; locating radio galaxies; how distances to radio galaxies are found; physics of radio galaxies; computer simulations of radio galaxies; and the evolution of radio galaxies with cosmic time. (JN)

  10. The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: tomographic BAO analysis of DR12 combined sample in configuration space

    NASA Astrophysics Data System (ADS)

    Wang, Yuting; Zhao, Gong-Bo; Chuang, Chia-Hsun; Ross, Ashley J.; Percival, Will J.; Gil-Marín, Héctor; Cuesta, Antonio J.; Kitaura, Francisco-Shu; Rodriguez-Torres, Sergio; Brownstein, Joel R.; Eisenstein, Daniel J.; Ho, Shirley; Kneib, Jean-Paul; Olmstead, Matthew D.; Prada, Francisco; Rossi, Graziano; Sánchez, Ariel G.; Salazar-Albornoz, Salvador; Thomas, Daniel; Tinker, Jeremy; Tojeiro, Rita; Vargas-Magaña, Mariana; Zhu, Fangzhou

    2017-08-01

    We perform a tomographic baryon acoustic oscillations (BAOs) analysis using the two-point galaxy correlation function measured from the combined sample of Baryon Oscillation Spectroscopic Survey Data Release 12 (BOSS DR12), which covers the redshift range of 0.2 < z < 0.75. Upon splitting the sample into multiple overlapping redshift slices to extract the redshift information of galaxy clustering, we obtain a measurement of DA(z)/rd and H(z)rd at nine effective redshifts with the full covariance matrix calibrated using MultiDark-Patchy mock catalogues. Using the reconstructed galaxy catalogues, we obtain the precision of 1.3-2.2 per cent for DA(z)/rd and 2.1-6.0 per cent for H(z)rd. To quantify the gain from the tomographic information, we compare the constraints on the cosmological parameters using our nine-bin BAO measurements, the consensus three-bin BAO and redshift space distortion measurements at three effective redshifts in Alam et al., and the non-tomographic (one-bin) BAO measurement at a single effective redshift. Comparing the nine-bin with one-bin constraint result, it can improve the dark energy Figure of Merit by a factor of 1.24 for the Chevallier-Polarski-Linder parametrization for equation-of-state parameter wDE. The errors of w0 and wa from nine-bin constraints are slightly improved when compared to the three-bin constraint result.

  11. Evolution of the mass, size, and star formation rate in high redshift merging galaxies. MIRAGE - A new sample of simulations with detailed stellar feedback

    NASA Astrophysics Data System (ADS)

    Perret, V.; Renaud, F.; Epinat, B.; Amram, P.; Bournaud, F.; Contini, T.; Teyssier, R.; Lambert, J.-C.

    2014-02-01

    Context. In Λ-CDM models, galaxies are thought to grow both through continuous cold gas accretion coming from the cosmic web and episodic merger events. The relative importance of these different mechanisms at different cosmic epochs is nevertheless not yet understood well. Aims: We aim to address questions related to galaxy mass assembly through major and minor wet merging processes in the redshift range 1 < z < 2, an epoch that corresponds to the peak of cosmic star formation history. A significant fraction of Milky Way-like galaxies are thought to have undergone an unstable clumpy phase at this early stage. We focus on the behavior of the young clumpy disks when galaxies are undergoing gas-rich galaxy mergers. Methods: Using the adaptive mesh-refinement code RAMSES, we build the Merging and Isolated high redshift Adaptive mesh refinement Galaxies (MIRAGE) sample. It is composed of 20 mergers and 3 isolated idealized disks simulations, which sample disk orientations and merger masses. Our simulations can reach a physical resolution of 7 parsecs, and include star formation, metal line cooling, metallicity advection, and a recent physically-motivated implementation of stellar feedback that encompasses OB-type stars radiative pressure, photo-ionization heating, and supernovae. Results: The star formation history of isolated disks shows a stochastic star formation rate, which proceeds from the complex behavior of the giant clumps. Our minor and major gas-rich merger simulations do not trigger starbursts, suggesting a saturation of the star formation due to the detailed accounting of stellar feedback processes in a turbulent and clumpy interstellar medium fed by substantial accretion from the circumgalactic medium. Our simulations are close to the normal regime of the disk-like star formation on a Schmidt-Kennicutt diagram. The mass-size relation and its rate of evolution in the redshift range 1 < z < 2 matches observations, suggesting that the inside-out growth

  12. Deep infrared galaxies

    NASA Technical Reports Server (NTRS)

    Ashby, Matthew; Houck, J. R.; Hacking, Perry B.

    1992-01-01

    High signal-to-noise ratio optical spectra of 17 infrared-bright emission-line galaxies near the north ecliptic pole are presented. Reddening-corrected line ratios forbidden O III 5007/H-beta, N II 6583/H-alpha, S II (6716 + 6731)/H-alpha, and O I 6300/H-alpha are used to discriminate between candidate energy generation mechanisms in each galaxy. These criteria have frequently been applied to optically selected samples of galaxies in the past, but this is the first time they have been applied to a set of faint flux-limited infrared-selected objects. The analysis indicates the sample contains seven starburst galaxies and three (AGN). However, seven galaxies in the present sample elude the classification scheme based on these line ratios. It is concluded that a two-component (starburst plus AGN) model for energy generation is inadequate for infrared galaxies.

  13. Xray cavities in a sample of 83 SPT-selected clusters galaxies. Tracing the evolution of AGN feedback in clusters of galaxies out to z=1.2

    SciTech Connect

    Hlavacek-Larrondo, J.; McDonald, M.; Benson, B. A.; Forman, W. R.; Allen, S. W.; Bleem, L. E.; Ashby, M. L. N.; Bocquet, S.; Brodwin, M.; Dietrich, J. P.; Jones, C.; Liu, J.; Reichardt, C. L.; Saliwanchik, B. R.; Saro, A.; Schrabback, T.; Song, J.; Stalder, B.; Vikhlinin, A.; Zenteno, A.

    2015-05-18

    X-ray cavities are key tracers of mechanical (or radio mode) heating arising from the active galactic nuclei (AGNs) in brightest cluster galaxies (BCGs). We report on a survey for X-ray cavities in 83 massive, high-redshift ($0.4\\lt z\\lt 1.2$) clusters of galaxies selected by their Sunyaev-Zel’dovich signature in the South Pole Telescope data. Based on Chandra X-ray images, we find a total of six clusters having symmetric pairs of surface brightness depressions consistent with the picture of radio jets inflating X-ray cavities in the intracluster medium (ICM). The majority of these detections are of relatively low significance and require deeper follow-up data in order to be confirmed. Further, this search will miss small (<10 kpc) X-ray cavities that are unresolved by Chandra at high ($z\\gtrsim 0.5$) redshift. Despite these limitations, our results suggest that the power generated by AGN feedback in BCGs has remained unchanged for over half of the age of the universe ($\\gt 7$ Gyr at $z\\sim 0.8$). On average, the detected X-ray cavities have powers of $(0.8-5)\\times {{10}^{45}}\\ {\\rm erg}\\ {{{\\rm s}}^{-1}}$, enthalpies of $(3-6)\\times {{10}^{59}}\\ {\\rm erg}$, and radii of ~17 kpc. Integrating over 7 Gyr, we find that the supermassive black holes in BCGs may have accreted 10(8) to several ${{10}^{9}}\\,{{M}_{\\odot }}$ of material to power these outflows. This level of accretion indicates that significant supermassive black hole growth may occur not only at early times, in the quasar era, but at late times as well. We also find that X-ray cavities at high redshift may inject an excess heat of 0.1–1.0 keV per particle into the hot ICM above and beyond the energy needed to offset cooling. Although this result needs to be confirmed, we note that the magnitude of excess heating is similar to the energy needed to preheat clusters, break self-similarity, and explain the excess entropy in hot atmospheres.

  14. Dust and star formation properties of a complete sample of local galaxies drawn from the Planck Early Release Compact Source Catalogue

    NASA Astrophysics Data System (ADS)

    Clemens, M. S.; Negrello, M.; De Zotti, G.; Gonzalez-Nuevo, J.; Bonavera, L.; Cosco, G.; Guarese, G.; Boaretto, L.; Salucci, P.; Baccigalupi, C.; Clements, D. L.; Danese, L.; Lapi, A.; Mandolesi, N.; Partridge, R. B.; Perrotta, F.; Serjeant, S.; Scott, D.; Toffolatti, L.

    2013-07-01

    We combine Planck High Frequency Instrument data at 857, 545, 353 and 217 GHz with data from Wide-field Infrared Survey Explorer (WISE), Spitzer, IRAS and Herschel to investigate the properties of a well-defined, flux-limited sample of local star-forming galaxies. A 545 GHz flux density limit was chosen so that the sample is 80 per cent complete at this frequency, and the resulting sample contains a total of 234 local, star-forming galaxies. We investigate the dust emission and star formation properties of the sample via various models and calculate the local dust mass function. Although single-component-modified blackbodies fit the dust emission longward of 80 μm very well, with a median β = 1.83, the known degeneracy between dust temperature and β also means that the spectral energy distributions are very well described by a dust component with dust emissivity index fixed at β = 2 and temperature in the range 10-25 K. Although a second, warmer dust component is required to fit shorter wavelength data, and contributes approximately a third of the total infrared emission, its mass is negligible. No evidence is found for a very cold (6-10 K) dust component. The temperature of the cold dust component is strongly influenced by the ratio of the star formation rate to the total dust mass. This implies, contrary to what is often assumed, that a significant fraction of even the emission from ˜20 K dust is powered by ongoing star formation, whether or not the dust itself is associated with star-forming clouds or `cirrus'. There is statistical evidence of a free-free contribution to the 217 GHz flux densities of ≲20 per cent. We find a median dust-to-stellar mass ratio of 0.0046; and that this ratio is anticorrelated with galaxy mass. There is good correlation between dust mass and atomic gas mass (median Md/MHI = 0.022), suggesting that galaxies that have more dust (higher values of Md/M*) have more interstellar medium in general. Our derived dust mass function

  15. The Massive and Distant Clusters of WISE Survey (MaDCoWS): Stellar mass fractions in a sample of infrared-selected galaxy clusters at z~1

    NASA Astrophysics Data System (ADS)

    Decker, Bandon; Brodwin, Mark

    2017-01-01

    Galaxy clusters are the largest gravitationally bound objects in the universe. In addition to being interesting objects in their own right, they are excellent laboratories in which to study galaxy evolution and the properties and abundance of galaxy clusters provide important tests for cosmology. The Massive and Distant Clusters of WISE Survey (MaDCoWS) is a high-redshift (z~1) survey that selects galaxy clusters in the infrared over nearly the full extragalactic sky using the Wide-field Infrared Survey Explorer (WISE) AllWISE data release. We have measured Sunyaev-Zel'dovich (SZ) masses for twelve of the MaDCoWS clusters lying in the range 0.9 < z <1.3 using the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and used follow-up Spitzer/IRAC rest-frame near-infrared observations to measure the stellar mass of these clusters. With these data, we have measured the stellar mass fraction, f_star, and it's relation to total mass for a sample of infrared-selected clusters at z~1. We repeated our analysis of stellar mass fraction on a sample of SZ-selected clusters from the South Pole Telescope (SPT)-SZ survey that lie in a comparable range of mass and redshift to our MaDCoWS clusters to compare the selection methods. We found no significant difference in the trend of stellar mass fraction-to-total mass between infrared and radio selections. Comparing to similar measurements in the local Universe, we find no evidence of strong evolution in the trend over the last 8 Gyr.

  16. Bright galaxies at z=9-11 from pure-parallel HST observations: Building a unique sample for JWST with Spitzer/IRAC

    NASA Astrophysics Data System (ADS)

    Bernard, Stephanie; Trenti, Michele; Bouwens, Rychard

    2016-08-01

    The combination of observations taken by Hubble and Spitzer revealed the unexpected presence of sources as bright as our own Milky Way as early as 400 Myr after the Big Bang, potentially highlighting a new highly efficient regime for star formation in L>L* galaxies at very early times. Yet, the sample of high-quality z>8 galaxies that have both HST and Spitzer/IRAC imaging is still very small, particularly at high luminosities. We propose here to remedy this situation and efficiently follow-up with Spitzer/IRAC the most promising z>8 sources from our Hubble Brightest of Reionizing Galaxies (BoRG) survey, which covers a footprint on the sky similar to CANDELS, provides a deeper search than ground-based surveys like UltraVISTA, and is robust against cosmic variance because of its 180 independent lines of sight. The proposed new 3.6 micron observations will continue the Spitzer cycle 12 BORG911 program and target 15 additional fields, leveraging over 300 new HST orbits (350 sqarcmin) to identify a final sample of about 5 to 10 bright galaxies at z >= 8.5. For optimal time use (just over 22 hours), our goal is to readily discriminate between z>8 sources (undetected or marginally detected in IRAC) and z~2 interlopers (strongly detected in IRAC) with just 1-2 hours per pointing. The high-quality candidates that we will identify with IRAC will be ideal targets for further studies to investigate the reionization state of the inter-galactic medium through near-IR Keck/VLT spectroscopy. They will also be uniquely suited to measurement of the redshift and stellar population properties through JWST/NIRSPEC observations, with the potential to elucidate how the first generations of stars are assembled in the earliest stages of the epoch of reionization.

  17. The Lyman alpha reference sample. VI. Lyman alpha escape from the edge-on disk galaxy Mrk 1486

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    Context. Recent numerical simulations suggest that the strength of the Lyman alpha (Lyα) line of star-forming disk galaxies strongly depends on the inclination at which they are observed: from edge-on to face-on, we expect to see a change from a strongly attenuated Lyα line to a strong Lyα emission line. Aims: We aim to understand how a strong Lyα emission line is able to escape from the low-redshift highly inclined (edge-on) disk galaxy Mrk 1486 (z ~ 0.0338). To our knowledge, this work is the first observational study of Lyα transport inside an edge-on disk galaxy. Methods: Using a large set of HST imaging and spectroscopic data, we investigated the interstellar medium (ISM) structure and the dominant source of Lyα radiation inside Mrk 1486. Moreover, using a 3D Monte Carlo Lyα radiation transfer code, we studied the radiative transfer of Lyα and UV continuum photons inside a 3D geometry of neutral hydrogen (HI) and dust that models the ISM structure at the galaxy center. Our numerical simulations predicted the Lyα line profile that we then compared to the one observed in the HST/COS spectrum of Mrk 1486. Results: While a pronounced Lyα absorption line emerges from the disk of Mrk 1486, very extended Lyα structures are observed at large radii from the galaxy center: a large Lyα-halo and two very bright Lyα regions located slightly above and below the disk plane. The analysis of IFU Hα spectroscopic data of Mrk 1486 indicates the presence of two bipolar outflowing halos of HI gas at the same location as these two bright Lyα regions. Comparing different diagnostic diagrams (such as [OIII]5007/Hβ versus [OI]6300/Hα) to photo- and shock-ionization models, we find that the Lyα production of Mrk 1486 is dominated by photoionization inside the galaxy disk. From this perspective, our numerical simulations succeed in reproducing the strength and shape of the observed Lyα emission line of Mrk 1486 by assuming a scenario in which the Lyα photons are

  18. Probabilistic distributions of M/L values for ultrafaint dwarf spheroidal galaxies: stochastic samplings of the initial mass function

    NASA Astrophysics Data System (ADS)

    Hernandez, X.

    2012-02-01

    We explore the ranges and distributions which will result for the intrinsic stellar mass-to-light ratio (M/L) values of single stellar populations, at fixed initial mass function (IMF), age and metallicity, from the discrete stochastic sampling of a probabilistic IMF. As the total mass of a certain stellar population tends to infinity, the corresponding M/L values quickly converge to fixed numbers associated with the particulars of the IMF, age, metallicity and star formation histories in question. When going to small stellar populations, however, a natural inherent spread will appear for the M/L values, which will become probabilistic quantities. For the recently discovered ultrafaint local dwarf spheroidal galaxies, with total luminosities dropping below 103LV/L⊙, it is important to asses the amplitude of the probabilistic spread in inherent M/L values mentioned above. The total baryonic masses of these systems are usually estimated from their observed luminosities, and the assumption of a fixed, deterministic M/L value, suitable for the infinite population limit of the assumed ages and metallicities of the stellar populations in question. This total baryonic masses are crucial for testing and calibrating of structure formation scenarios, as the local ultrafaint dwarf spheroidals represent the most extreme galactic scales known. Also, subject to reliable M/L values is the use of these systems as possible discriminants between dark matter and modified gravity theories. By simulating large collections of stellar populations, each consisting of a particular collection of individual stars, we compute statistical distributions for the resulting M/L values. We find that for total numbers of stars in the range of what is observed for the local ultrafaint dwarf spheroidals, the inherent M/L values of stellar populations can be expected to vary by factors of upwards of 3, interestingly, systematically skewed towards higher values than what is obtained for the

  19. Velocity dispersions and dynamical masses for a large sample of quiescent galaxies at z >1: Improved measures of the growth in mass and size

    SciTech Connect

    Belli, Sirio; Newman, Andrew B.; Ellis, Richard S.

    2014-03-10

    We present Keck LRIS spectroscopy for a sample of 103 massive (M > 10{sup 10.6} M {sub ☉}) galaxies with redshifts 0.9 < z < 1.6. Of these, 56 are quiescent with high signal-to-noise absorption line spectra, enabling us to determine robust stellar velocity dispersions for the largest sample yet available beyond a redshift of 1. Together with effective radii measured from deep Hubble Space Telescope images, we calculate dynamical masses and address key questions relating to the puzzling size growth claimed by many observers for quiescent galaxies over the redshift interval 0 < z < 2. Our large sample provides the first opportunity to carefully examine the relationship between stellar and dynamical masses at high redshift. We find this relation closely follows that determined locally. We also confirm the utility of the locally established empirical calibration which enables high-redshift velocity dispersions to be estimated photometrically, and we determine its accuracy to be 35%. To address recent suggestions that progenitor bias—the continued arrival of recently quenched larger galaxies—can largely explain the size evolution of quiescent galaxies, we examine the growth at fixed velocity dispersion assuming this quantity is largely unaffected by the merger history. Using the velocity dispersion-age relation observed in the local universe, we demonstrate that significant size and mass growth have clearly occurred in individual systems. Parameterizing the relation between mass and size growth over 0 < z < 1.6 as R∝M {sup α}, we find α = 1.6 ± 0.3, in agreement with theoretical expectations from simulations of minor mergers. Relaxing the assumption that the velocity dispersion is unchanging, we examine growth assuming a constant ranking in galaxy velocity dispersion. This approach is applicable only to the large-dispersion tail of the distribution, but yields a consistent growth rate of α = 1.4 ± 0.2. Both methods confirm that progenitor bias alone is

  20. Bias properties of extragalactic distance indicators. 3: Analysis of Tully-Fisher distances for the Mathewson-Ford-Buchhorn sample of 1355 galaxies

    NASA Astrophysics Data System (ADS)

    Federspiel, Martin; Sandage, Allan; Tammann, G. A.

    1994-07-01

    The observational selection bias properties of the large Mathewson-Ford-Buchhorn (MFB) sample of axies are demonstrated by showing that the apparent Hubble constant incorrectly increases outward when determined using Tully-Fisher (TF) photometric distances that are uncorrected for bias. It is further shown that the value of H0 so determined is also multi-valued at a given redshift when it is calculated by the TF method using galaxies with differenct line widths. The method of removing this unphysical contradiction is developed following the model of the bias set out in Paper II. The model developed further here shows that the appropriate TF magnitude of a galaxy that is drawn from a flux-limited catalog not only is a function of line width but, even in the most idealistic cases, requires a triple-entry correction depending on line width, apparent magnitude, and catalog limit. Using the distance-limited subset of the data, it is shown that the mean intrinsic dispersion of a bias-free TF relation is high. The dispersion depends on line width, decreasing from sigma(M) = 0.7 mag for galaxies with rotational velocities less than 100 km s(exp-1) to sigma(M) = 0.4 mag for galaxies with rotational velocities greater than 250 km s(exp-1). These dispersions are so large that the random errors of the bias-free TF distances are too gross to detect any peculiar motions of individual galaxies, but taken together the data show again the offset of 500 km s(exp-1) fond both by Dressler & Faber and by MFB for galaxies in the direction of the putative Great Attractor but described now in a different way. The maximum amplitude of the bulk streaming motion at the Local Group is approximately 500 km s(exp-1) but the perturbation dies out, approaching the Machian frame defined by the CMB at a distance of approximately 80 Mpc (v is approximately 4000 km s-1). This decay to zero perturbation at v is approximately 4000 km s-1 argues against existing models with a single attraction at

  1. Bias properties of extragalactic distance indicators. 3: Analysis of Tully-Fisher distances for the Mathewson-Ford-Buchhorn sample of 1355 galaxies

    NASA Technical Reports Server (NTRS)

    Federspiel, Martin; Sandage, Allan; Tammann, G. A.

    1994-01-01

    The observational selection bias properties of the large Mathewson-Ford-Buchhorn (MFB) sample of axies are demonstrated by showing that the apparent Hubble constant incorrectly increases outward when determined using Tully-Fisher (TF) photometric distances that are uncorreted for bias. It is further shown that the value of H(sub 0) so determined is also multivlaued at a given redshift when it is calculated by the TF method using galaxies with differenct line widths. The method of removing this unphysical contradiction is developed following the model of the bias set out in Paper II. The model developed further here shows that the appropriate TF magnitude of a galaxy that is drawn from a flux-limited catalog not only is a function of line width but, even in the most idealistic cases, requires a triple-entry correction depending on line width, apparent magnitude, and catalog limit. Using the distance-limited subset of the data, it is shown that the mean intrinsic dispersion of a bias-free TF relation is high. The dispersion depends on line width, decreasing from sigma(M) = 0.7 mag for galaxies with rotational velocities less than 100 km s(exp-1) to sigma(M) = 0.4 mag for galaxies with rotational velocities greater than 250 km s(exp-1). These dispersions are so large that the random errors of the bias-free TF distances are too gross to detect any peculiar motions of individual galaxies, but taken together the data show again the offset of 500 km s(exp-1) fond both by Dressler & Faber and by MFB for galaxies in the direction of the putative Great Attractor but described now in a different way. The maximum amplitude of the bulk streaming motion at the Local Group is approximately 500 km s(exp-1) but the perturbation dies out, approaching the Machian frame defined by the CMB at a distance of approximately 80 Mpc (v is approximately 4000 km s(exp -1)). This decay to zero perturbation at v is approximately 4000 km s(exp -1) argues against existing models with a single

  2. Bias properties of extragalactic distance indicators. 3: Analysis of Tully-Fisher distances for the Mathewson-Ford-Buchhorn sample of 1355 galaxies

    NASA Technical Reports Server (NTRS)

    Federspiel, Martin; Sandage, Allan; Tammann, G. A.

    1994-01-01

    The observational selection bias properties of the large Mathewson-Ford-Buchhorn (MFB) sample of axies are demonstrated by showing that the apparent Hubble constant incorrectly increases outward when determined using Tully-Fisher (TF) photometric distances that are uncorreted for bias. It is further shown that the value of H(sub 0) so determined is also multivlaued at a given redshift when it is calculated by the TF method using galaxies with differenct line widths. The method of removing this unphysical contradiction is developed following the model of the bias set out in Paper II. The model developed further here shows that the appropriate TF magnitude of a galaxy that is drawn from a flux-limited catalog not only is a function of line width but, even in the most idealistic cases, requires a triple-entry correction depending on line width, apparent magnitude, and catalog limit. Using the distance-limited subset of the data, it is shown that the mean intrinsic dispersion of a bias-free TF relation is high. The dispersion depends on line width, decreasing from sigma(M) = 0.7 mag for galaxies with rotational velocities less than 100 km s(exp-1) to sigma(M) = 0.4 mag for galaxies with rotational velocities greater than 250 km s(exp-1). These dispersions are so large that the random errors of the bias-free TF distances are too gross to detect any peculiar motions of individual galaxies, but taken together the data show again the offset of 500 km s(exp-1) fond both by Dressler & Faber and by MFB for galaxies in the direction of the putative Great Attractor but described now in a different way. The maximum amplitude of the bulk streaming motion at the Local Group is approximately 500 km s(exp-1) but the perturbation dies out, approaching the Machian frame defined by the CMB at a distance of approximately 80 Mpc (v is approximately 4000 km s(exp -1)). This decay to zero perturbation at v is approximately 4000 km s(exp -1) argues against existing models with a single

  3. The extended ROSAT-ESO Flux-Limited X-ray Galaxy Cluster Survey (REFLEX II) - III. Construction of the first flux-limited supercluster sample

    NASA Astrophysics Data System (ADS)

    Chon, Gayoung; Böhringer, Hans; Nowak, Nina

    2013-03-01

    We present the first supercluster catalogue constructed with the extended ROSAT-ESO Flux-Limited X-ray (REFLEX II) Galaxy Cluster survey data, which comprises 919 X-ray selected galaxy clusters with a flux limit of 1.8 × 10-12 erg s-1 cm-2. Based on this cluster catalogue we construct a supercluster catalogue using a friends-of-friends algorithm with a linking length depending on the (local) cluster density, which thus varies with redshift. The resulting catalogue comprises 164 superclusters at redshift z ≤ 0.4. The choice of the linking length in the friends-of-friends method modifies the properties of the superclusters. We study the properties of different catalogues such as the distributions of the redshift, extent and multiplicity by varying the choice of parameters. In addition to the supercluster catalogue for the entire REFLEX II sample, we compile a large volume-limited cluster sample from REFLEX II with the redshift and luminosity constraints of z ≤ 0.1 and LX ≥ 5 × 1043 erg s-1. With this catalogue we construct a volume-limited sample of superclusters. This sample is built with a homogeneous linking length, and hence selects effectively the same type of superclusters. By increasing the luminosity cut we can build a hierarchical tree structure of the volume-limited samples, where systems at the top of the tree are only formed via the most luminous clusters. This allows us to test if the same superclusters are found when only the most luminous clusters are visible, comparable to the situation at higher redshift in the REFLEX II sample. We find that the selection of superclusters is very robust, independent of the luminosity cut, and the contamination of spurious superclusters among cluster pairs is expected to be small. Numerical simulations and observations of the substructure of clusters suggest that regions of high cluster number density provide an astrophysically different environment for galaxy clusters, where the mass function and X

  4. The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: tomographic BAO analysis of DR12 combined sample in Fourier space

    NASA Astrophysics Data System (ADS)

    Zhao, Gong-Bo; Wang, Yuting; Saito, Shun; Wang, Dandan; Ross, Ashley J.; Beutler, Florian; Grieb, Jan Niklas; Chuang, Chia-Hsun; Kitaura, Francisco-Shu; Rodriguez-Torres, Sergio; Percival, Will J.; Brownstein, Joel R.; Cuesta, Antonio J.; Eisenstein, Daniel J.; Gil-Marín, Héctor; Kneib, Jean-Paul; Nichol, Robert C.; Olmstead, Matthew D.; Prada, Francisco; Rossi, Graziano; Salazar-Albornoz, Salvador; Samushia, Lado; Sánchez, Ariel G.; Thomas, Daniel; Tinker, Jeremy L.; Tojeiro, Rita; Weinberg, David H.; Zhu, Fangzhou

    2017-04-01

    We perform a tomographic baryon acoustic oscillations (BAO) analysis using the monopole, quadrupole and hexadecapole of the redshift-space galaxy power spectrum measured from the pre-reconstructed combined galaxy sample of the completed Sloan Digital Sky Survey Baryon Oscillation Spectroscopic Survey (BOSS) Data Release12 covering the redshift range of 0.20 < z < 0.75. By allowing for overlap between neighbouring redshift slices, we successfully obtained the isotropic and anisotropic BAO distance measurements within nine redshift slices to a precision of 1.5-3.4 per cent for DV/rd, 1.8-4.2 per cent for DA/rd and 3.7-7.5 per cent for H rd, depending on effective redshifts. We provide our BAO measurement of DA/rd and H rd with the full covariance matrix, which can be used for cosmological implications. Our measurements are consistent with those presented in Alam et al., in which the BAO distances are measured at three effective redshifts. We constrain dark energy parameters using our measurements and find an improvement of the Figure-of-Merit of dark energy in general due to the temporal BAO information resolved. This paper is a part of a set that analyses the final galaxy clustering data set from BOSS.

  5. The Stellar Population and Emitting Gas in the Inner 2-5-KPC for a Sample of Nine SEYFERT-2 Galaxies

    NASA Astrophysics Data System (ADS)

    Storchi-Bergmann, T.; Bica, E.; Pastoriza, M. G.

    1990-08-01

    We analyse the stellar population and the emitting gas in the inner 2-5 kpc of a sample of nine Seyfert 2 galaxies, using 5-A resolution spectra in the range 3600-7000 A. The typical population is old and moderately strong-lined, except in IC 5135 which presents star-forming events. The emission-line spectrum is studied after subtraction of the stellar population. Broad Hα components (FWHM = 2000 km s^-1^) were found for five of the galaxies. The line widths correlate with the critical densities for the forbidden lines in four of the galaxies and with the ionization potential in three of these, indicating the presence of density stratification and ionization structure. Comparison of our emission-line ratios with smaller aperture data obtained from the literature reveal important changes in the values due to contamination by surrounding gas. Using photo-ionization models we derive gas abundances between solar and two-times solar, with an overabundance of nitrogen in NGC 4939 and 6890, and of nitrogen and sulphur in NGC 1667, relative to the other heavy elements.

  6. The 2XMMi/SDSS Galaxy Cluster Survey. I. The first cluster sample and X-ray luminosity-temperature relation

    NASA Astrophysics Data System (ADS)

    Takey, A.; Schwope, A.; Lamer, G.

    2011-10-01

    We present a catalogue of X-ray selected galaxy clusters and groups as a first release of the 2XMMi/SDSS Galaxy Cluster Survey. The survey is a search for galaxy clusters detected serendipitously in observations with XMM-Newton in the footprint of the Sloan Digital Sky Survey (SDSS). The main aims of the survey are to identify new X-ray galaxy clusters, investigate their X-ray scaling relations, identify distant cluster candidates, and study the correlation of the X-ray and optical properties. In this paper, we describe the basic strategy to identify and characterize the X-ray cluster candidates that currently comprise 1180 objects selected from the second XMM-Newton serendipitous source catalogue (2XMMi-DR3). Cross-correlation of the initial catalogue with recently published optically selected SDSS galaxy cluster catalogues yields photometric redshifts for 275 objects. Of these, 182 clusters have at least one member with a spectroscopic redshift from existing public data (SDSS-DR8). We developed an automated method to reprocess the XMM-Newton X-ray observations, determine the optimum source extraction radius, generate source and background spectra, and derive the temperatures and luminosities of the optically confirmed clusters. Here we present the X-ray properties of the first cluster sample, which comprises 175 clusters, among which 139 objects are new X-ray discoveries while the others were previously known as X-ray sources. For each cluster, the catalogue provides: two identifiers, coordinates, temperature, flux [0.5-2] keV, luminosity [0.5-2] keV extracted from an optimum aperture, bolometric luminosity L500, total mass M500, radius R500, and the optical properties of the counterpart. The first cluster sample from the survey covers a wide range of redshifts from 0.09 to 0.61, bolometric luminosities L500 = 1.9 × 1042-1.2 × 1045 erg s-1, and masses M500 = 2.3 × 1013-4.9 × 1014 M⊙. We extend the relation between the X-ray bolometric luminosity L500 and

  7. THE ATACAMA COSMOLOGY TELESCOPE: PHYSICAL PROPERTIES AND PURITY OF A GALAXY CLUSTER SAMPLE SELECTED VIA THE SUNYAEV-ZEL'DOVICH EFFECT

    SciTech Connect

    Menanteau, Felipe; Acquaviva, Viviana; Baker, Andrew J.; Deshpande, Amruta J.; Gonzalez, Jorge; Juin, Jean-Baptiste; Aguirre, Paula; Barrientos, L. Felipe; Duenner, Rolando; Marriage, Tobias A.; Reese, Erik D.; Devlin, Mark J.; Dicker, Simon; Appel, John William; Essinger-Hileman, Thomas; Fowler, Joseph W.; Battistelli, Elia S.; Bond, J. Richard; Das, Sudeep; Dunkley, Joanna

    2010-11-10

    We present optical and X-ray properties for the first confirmed galaxy cluster sample selected by the Sunyaev-Zel'dovich effect (SZE) from 148 GHz maps over 455 deg{sup 2} of sky made with the Atacama Cosmology Telescope (ACT). These maps, coupled with multi-band imaging on 4 m class optical telescopes, have yielded a sample of 23 galaxy clusters with redshifts between 0.118 and 1.066. Of these 23 clusters, 10 are newly discovered. The selection of this sample is approximately mass limited and essentially independent of redshift. We provide optical positions, images, redshifts, and X-ray fluxes and luminosities for the full sample, and X-ray temperatures of an important subset. The mass limit of the full sample is around 8.0 x 10{sup 14} M{sub sun}, with a number distribution that peaks around a redshift of 0.4. For the 10 highest significance SZE-selected cluster candidates, all of which are optically confirmed, the mass threshold is 1 x 10{sup 15} M{sub sun} and the redshift range is 0.167-1.066. Archival observations from Chandra, XMM-Newton, and ROSAT provide X-ray luminosities and temperatures that are broadly consistent with this mass threshold. Our optical follow-up procedure also allowed us to assess the purity of the ACT cluster sample. Eighty (one hundred) percent of the 148 GHz candidates with signal-to-noise ratios greater than 5.1 (5.7) are confirmed as massive clusters. The reported sample represents one of the largest SZE-selected sample of massive clusters over all redshifts within a cosmologically significant survey volume, which will enable cosmological studies as well as future studies on the evolution, morphology, and stellar populations in the most massive clusters in the universe.

  8. The Atacama Cosmology Telescope: Physical Properties and Purity of a Galaxy Cluster Sample Selected Via the Sunyaev-Zel'Dovich Effect

    NASA Technical Reports Server (NTRS)

    Menanteau, Felipe; Gonzalez, Jorge; Juin, Jean-Baptiste; Marriage, Tobias; Reese, Erik D.; Acquaviva, Viviana; Aguirre, Paula; Appel, John Willam; Baker, Andrew J.; Barrientos, L. Felipe; hide

    2010-01-01

    We present optical and X-ray properties for the first confirmed galaxy cluster sample selected by the Sunyaev-Zel'dovich Effect from 148 GHz maps over 455 square degrees of sky made with the Atacama Cosmology Telescope. These maps. coupled with multi-band imaging on 4-meter-class optical telescopes, have yielded a sample of 23 galaxy clusters with redshifts between 0.118 and 1.066. Of these 23 clusters, 10 are newly discovered. The selection of this sample is approximately mass limited and essentially independent of redshift. We provide optical positions, images, redshifts and X-ray fluxes and luminosities for the full sample, and X-ray temperatures of an important subset. The mass limit of the full sample is around 8.0 x 10(exp 14) Stellar Mass. with a number distribution that peaks around a redshift of 0.4. For the 10 highest significance SZE-selected cluster candidates, all of which are optically confirmed, the mass threshold is 1 x 10(exp 15) Stellar Mass and the redshift range is 0.167 to 1.066. Archival observations from Chandra, XMM-Newton. and ROSAT provide X-ray luminosities and temperatures that are broadly consistent with this mass threshold. Our optical follow-up procedure also allowed us to assess the purity of the ACT cluster sample. Eighty (one hundred) percent of the 148 GHz candidates with signal-to-noise ratios greater than 5.1 (5.7) are confirmed as massive clusters. The reported sample represents one of the largest SZE-selected sample of massive clusters over all redshifts within a cosmologically-significant survey volume, which will enable cosmological studies as well as future studies on the evolution, morphology, and stellar populations in the most massive clusters in the Universe.

  9. MULTI-WAVELENGTH STUDY OF A COMPLETE IRAC 3.6 {mu}m SELECTED GALAXY SAMPLE: A FAIR CENSUS OF RED AND BLUE POPULATIONS AT REDSHIFTS 0.4-1.2

    SciTech Connect

    Huang, J.-S.; Faber, S. M.; Koo, D.; Rigopoulou, D.; Magdis, G.; Newman, J.; Shu, C.; Luo, Z.; Ashby, M. L. N.; Wang, T.; Willner, S. P.; Fazio, G. G.; Barmby, P.; Coil, A.; Zheng, X. Z.

    2013-03-20

    We present a multi-wavelength study of a 3.6 {mu}m selected galaxy sample in the Extended Groth Strip (EGS). The sample is complete for galaxies with stellar mass >10{sup 9.5} M{sub Sun} and redshift 0.4 < z < 1.2. In this redshift range, the Infrared Array Camera 3.6 {mu}m band measures the rest-frame near-infrared band, permitting nearly unbiased selection with respect to both quiescent and star-forming galaxies. The numerous spectroscopic redshifts available in the EGS are used to train an artificial neural network to estimate photometric redshifts. The distribution of photometric redshift errors is Gaussian with standard deviation {approx}0.025(1 + z), and the fraction of redshift failures (>3{sigma} errors) is about 3.5%. A new method of validation based on pair statistics confirms the estimate of standard deviation even for galaxies lacking spectroscopic redshifts. Basic galaxy properties measured include rest-frame U - B colors, B- and K-band absolute magnitudes, and stellar masses. We divide the sample into quiescent and star-forming galaxies according to their rest-frame U - B colors and 24-3.6 {mu}m flux density ratios and derive rest K-band luminosity functions and stellar mass functions for quiescent, star-forming, and all galaxies. The results show that massive, quiescent galaxies were in place by z Almost-Equal-To 1, but lower mass galaxies generally ceased their star formation at later epochs.

  10. Constraint on the cosmological f(R) model from the multipole power spectrum of the SDSS luminous red galaxy sample and prospects for a future redshift survey

    SciTech Connect

    Yamamoto, Kazuhiro; Nakamura, Gen; Narikawa, Tatsuya; Sato, Takahiro; Huetsi, Gert

    2010-05-15

    A constraint on the viable f(R) model is investigated by confronting theoretical predictions with the multipole power spectrum of the luminous red galaxy sample of the Sloan Digital Sky Survey, data release 7. We obtain a constraint on the Compton wavelength parameter of the f(R) model on the scales of cosmological large-scale structure. A prospect of constraining the Compton wavelength parameter with a future redshift survey is also investigated. The usefulness of the redshift-space distortion for testing the gravity theory on cosmological scales is demonstrated.

  11. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: measuring DA and H at z = 0.57 from the baryon acoustic peak in the Data Release 9 spectroscopic Galaxy sample

    NASA Astrophysics Data System (ADS)

    Anderson, Lauren; Aubourg, Eric; Bailey, Stephen; Beutler, Florian; Bolton, Adam S.; Brinkmann, J.; Brownstein, Joel R.; Chuang, Chia-Hsun; Cuesta, Antonio J.; Dawson, Kyle S.; Eisenstein, Daniel J.; Ho, Shirley; Honscheid, Klaus; Kazin, Eyal A.; Kirkby, David; Manera, Marc; McBride, Cameron K.; Mena, O.; Nichol, Robert C.; Olmstead, Matthew D.; Padmanabhan, Nikhil; Palanque-Delabrouille, N.; Percival, Will J.; Prada, Francisco; Ross, Ashley J.; Ross, Nicholas P.; Sánchez, Ariel G.; Samushia, Lado; Schlegel, David J.; Schneider, Donald P.; Seo, Hee-Jong; Strauss, Michael A.; Thomas, Daniel; Tinker, Jeremy L.; Tojeiro, Rita; Verde, Licia; Wake, David; Weinberg, David H.; Xu, Xiaoying; Yeche, Christophe

    2014-03-01

    We present measurements of the angular diameter distance to and Hubble parameter at z = 0.57 from the measurement of the baryon acoustic peak in the correlation of galaxies from the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey. Our analysis is based on a sample from Data Release 9 of 264 283 galaxies over 3275 square degrees in the redshift range 0.43 < z < 0.70. We use two different methods to provide robust measurement of the acoustic peak position across and along the line of sight in order to measure the cosmological distance scale. We find DA(0.57) = 1408 ± 45 Mpc and H(0.57) = 92.9 ± 7.8 km s-1 Mpc-1 for our fiducial value of the sound horizon. These results from the anisotropic fitting are fully consistent with the analysis of the spherically averaged acoustic peak position presented in Anderson et al. Our distance measurements are a close match to the predictions of the standard cosmological model featuring a cosmological constant and zero spatial curvature.

  12. EXPLAINING THE [C II]157.7 {mu}m DEFICIT IN LUMINOUS INFRARED GALAXIES-FIRST RESULTS FROM A HERSCHEL/PACS STUDY OF THE GOALS SAMPLE

    SciTech Connect

    Diaz-Santos, T.; Armus, L.; Howell, J. H.; Surace, J. A.; Charmandaris, V.; Murphy, E. J.; Haan, S.; Inami, H.; Malhotra, S.; Meijerink, R.; Stacey, G.; Petric, A. O.; Lu, N.; Veilleux, S.; Van der Werf, P. P.; Lord, S.; Appleton, P.; and others

    2013-09-01

    We present the first results of a survey of the [C II]157.7 {mu}m emission line in 241 luminous infrared galaxies (LIRGs) comprising the Great Observatories All-sky LIRG Survey (GOALS) sample, obtained with the PACS instrument on board the Herschel Space Observatory. The [C II] luminosities, L{sub [C{sub II]}}, of the LIRGs in GOALS range from {approx}10{sup 7} to 2 Multiplication-Sign 10{sup 9} L{sub Sun }. We find that LIRGs show a tight correlation of [C II]/FIR with far-IR (FIR) flux density ratios, with a strong negative trend spanning from {approx}10{sup -2} to 10{sup -4}, as the average temperature of dust increases. We find correlations between the [C II]/FIR ratio and the strength of the 9.7 {mu}m silicate absorption feature as well as with the luminosity surface density of the mid-IR emitting region ({Sigma}{sub MIR}), suggesting that warmer, more compact starbursts have substantially smaller [C II]/FIR ratios. Pure star-forming LIRGs have a mean [C II]/FIR {approx} 4 Multiplication-Sign 10{sup -3}, while galaxies with low polycyclic aromatic hydrocarbon (PAH) equivalent widths (EWs), indicative of the presence of active galactic nuclei (AGNs), span the full range in [C II]/FIR. However, we show that even when only pure star-forming galaxies are considered, the [C II]/FIR ratio still drops by an order of magnitude, from 10{sup -2} to 10{sup -3}, with {Sigma}{sub MIR} and {Sigma}{sub IR}, implying that the [C II]157.7 {mu}m luminosity is not a good indicator of the star formation rate (SFR) for most local LIRGs, for it does not scale linearly with the warm dust emission most likely associated to the youngest stars. Moreover, even in LIRGs in which we detect an AGN in the mid-IR, the majority (2/3) of galaxies show [C II]/FIR {>=} 10{sup -3} typical of high 6.2 {mu}m PAH EW sources, suggesting that most AGNs do not contribute significantly to the FIR emission. We provide an empirical relation between the [C II]/FIR and the specific SFR for star

  13. Effects of Data Sampling on the Results of Fourier Analysis of Radial-Velocity Fields in Spiral-Galaxy Disks

    NASA Astrophysics Data System (ADS)

    Burlak, A. N.; Zasov, A. V.; Fridman, A. M.; Khoruzhi, O. V.

    2000-12-01

    Our main goal is to investigate the effects of data incompleteness on the results of Fourier analysis of line-of-sight velocity fields in the disks of spiral galaxies. We have carried out a number of numerical experiments, first with an artificially created simple velocity field and then with the velocity fields of two real galaxies, which qualitatively differ in data filling: NGC 157 and NGC 3631 with good and bad data filling, respectively. The field of purely circular velocities is chosen as the simplest artificial velocity field, because the circular velocities of spiral galaxies are much high than the residual (noncircular) velocities. Superimposing a "mask" simulating blank spots (holes) in the map of observational data on this artificial field has no effect on the results of Fourier analysis of this simplest field. A similar result is obtained for real galaxies with good data filling of the observed velocity fields. Superimposing arbitrarily shaped masks on the observed velocity field of NGC 157 in such a way that the field was filled by a mere 50% (at each radius) could not change appreciably the radial variations of large-scale Fourier harmonics. The situation qualitatively changes in attempting to fill the holes in the observed velocity field of NGC 3631 in some way. When missing velocities are artificially introduced by using the simplest model of purely circular gas rotation, the amplitudes and phases of the principal Fourier harmonics are distorted. In particular, a substantial distortion of the third harmonic also causes an increase in the error when determining the corotation radius from data of the filled field. When the filling of the velocity field is increased by degrading the spatial resolution, the amplitudes of most harmonics decrease throughout the entire disk region; as a result, their radial variations are smoothed out and the behavior of harmonic phases in the range of moderately high initial amplitudes can be distorted. An abnormal

  14. Morphology of Distant Galaxies

    NASA Astrophysics Data System (ADS)

    King, Ivan

    1991-07-01

    This is a proposal to study the morphology of distant galaxies, a field that has lagged far behind what has been learned from spectroscopic work. The targeted galaxies all have been extensively observed from the ground. Nearly all are in the redshift range 0.24-0.65. Ground-based data include broad-baseline 4-color photometry and, in nearly all cases, redshifts. The targets include a rich X-ray cluster that is surprisingly deficient in blue galaxies, and three other fields that each have numerous galaxies that have been richly observed from the ground. Each field will be observed with the WFC, while a parallel observation observes a similarly well-studied galaxy with the FOC at greater resolving power. These observations will take the first crucial step toward investigating the morphology of the rich sample of medium-redshift galaxies in the Koo-Kron redshift surveys.

  15. Luminosity Functions Of Xxl Clusters Galaxies

    NASA Astrophysics Data System (ADS)

    Ricci, Marina; Maurogordato, Sophie; Benoist, Christophe; XXL Consortium

    2017-06-01

    The galaxy luminosity function (LF) is a powerful statistical tool to investigate galaxy evolution. In particular the study of cluster galaxies LFs gives information about environmental effects and how galaxies populate their parent dark matter halos. In this poster we present our work on the galaxy LF of X-ray detected galaxy clusters from the XXL survey. The sample consists of 173 galaxy groups/clusters spanning a wide range in both mass (M500 from 1013 to 1015 solar masses ) and redshit (0.03 < z < 1.22). The main goal is to investigate the effect of evolution and cluster masses on the luminosity distribution of cluster galaxies.

  16. Redshift-space distortions of galaxies, clusters, and AGN. Testing how the accuracy of growth rate measurements depends on scales and sample selections

    NASA Astrophysics Data System (ADS)

    Marulli, Federico; Veropalumbo, Alfonso; Moscardini, Lauro; Cimatti, Andrea; Dolag, Klaus

    2017-03-01

    Aims: Redshift-space clustering anisotropies caused by cosmic peculiar velocities provide a powerful probe to test the gravity theory on large scales. However, to extract unbiased physical constraints, the clustering pattern has to be modelled accurately, taking into account the effects of non-linear dynamics at small scales, and properly describing the link between the selected cosmic tracers and the underlying dark matter field. Methods: We used a large hydrodynamic simulation to investigate how the systematic error on the linear growth rate, f, caused by model uncertainties, depends on sample selections and co-moving scales. Specifically, we measured the redshift-space two-point correlation function of mock samples of galaxies, galaxy clusters and active galactic nuclei, extracted from the Magneticum simulation, in the redshift range 0.2 ≤ z ≤ 2, and adopting different sample selections. We estimated fσ8 by modelling both the monopole and the full two-dimensional anisotropic clustering, using the dispersion model. Results: We find that the systematic error on fσ8 depends significantly on the range of scales considered for the fit. If the latter is kept fixed, the error depends on both redshift and sample selection due to the scale-dependent impact of non-linearities if not properly modelled. Concurrently, we show that it is possible to achieve almost unbiased constraints on fσ8 provided that the analysis is restricted to a proper range of scales that depends non-trivially on the properties of the sample. This can have a strong impact on multiple tracer analyses, and when combining catalogues selected at different redshifts.

  17. Lyman Alpha Galaxies and Galaxy Formation Scenarios

    NASA Astrophysics Data System (ADS)

    Malhotra, Sangeeta; Rhoads, James; Dey, Arjun; Jannuzi, Buell

    2003-02-01

    The Large Area Lyman Alpha survey has successfully identified the population of young Lyα emitting galaxies predicted over 30 years ago. High equivalent widths of Lyα line in these sources suggest that they are a very young (age < 10^7 years), metal poor, population of stars at redshifts 4.5, 5.7 and 6.6, making them very interesting objects to study in the context of galaxy formation scenarios. We have begun to do exactly this using the correlation function of LALA galaxies, with fairly puzzling results. Before this leads to more complications in theoretical galaxy formation scenarios, we would like to put the observational results on a firm footing. In order to do that we ask for one night of Keck/Deimos time for spectroscopic confirmation of 50 secure LALA sources at z=4.5, and a similar number of fainter sources, in order to (1) characterize the completeness of this survey, and (2) weed out foreground emission line galaxies which affect the small scale correlation function. The excellent match between wide-field capabilities of DEIMOS and the LALA survey will allow the most complete confirmation and characterization of the high redshift Lyα population yet in terms of photometric sample reliability, while our planned spectra of foreground emission line galaxies will lead to a characterization of emission line selected star-forming galaxies at 0.25 < z < 1.5. We will use our spectroscopic sample to obtain a clean measurement of the small scale correlations among Lyα galaxies (which are clearly seen in our photometric sample). This will let us understand the halo mass, occupancy number, and duty cycle of these objects, and hence better how Lyα sources fit into the bigger picture of galaxy formation.

  18. Empirical ugri-UBVRc transformations for galaxies

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Dale, Daniel A.; Johnson, Benjamin D.; Van Zee, Liese; Lee, Janice C.; Kennicutt, Robert C.; Calzetti, Daniela; Staudaher, Shawn M.; Engelbracht, Charles W.

    2014-11-01

    We present empirical colour transformations between Sloan Digital Sky Survey ugri and Johnson-Cousins UBVRc photometry for nearby galaxies (D < 11 Mpc). We use the Local Volume Legacy (LVL) galaxy sample where there are 90 galaxies with overlapping observational coverage for these two filter sets. The LVL galaxy sample consists of normal, non-starbursting galaxies. We also examine how well the LVL galaxy colours are described by previous transformations derived from standard calibration stars and model-based galaxy templates. We find significant galaxy colour scatter around most of the previous transformation relationships. In addition, the previous transformations show systematic offsets between transformed and observed galaxy colours which are visible in observed colour-colour trends. The LVL-based galaxy transformations show no systematic colour offsets and reproduce the observed colour-colour galaxy trends.

  19. A search for giant flares from soft gamma-ray repeaters in nearby galaxies in the Konus-WIND short burst sample

    NASA Astrophysics Data System (ADS)

    Svinkin, D. S.; Hurley, K.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.

    2015-02-01

    The knowledge of the rate of soft gamma-ray repeater (SGR) giant flares (GFs) is important for understanding the GF mechanism and the SGR energy budget in the framework of the magnetar model. We estimate the upper limit to the rate using the results of an extensive search for extragalactic SGR GFs among 140 short gamma-ray bursts detected between 1994 and 2010 by Konus-WIND using Interplanetary Network (IPN) localizations and temporal parameters. We show that Konus-WIND and the IPN are capable of detecting GFs with energies of 2.3 × 1046 erg (which is the energy of the GF from SGR 1806-20 assuming a distance of 15 kpc) at distances of up to ˜30 Mpc and GFs with energies of ≲ 1045 erg (which is the energy of the GF from SGR 0526-66) at distances of up to ≈6 Mpc. Using a sample of 1896 nearby galaxies, we found that only two bursts, GRB 051103 and GRB 070201, have a low chance coincidence probability between an IPN localization and a nearby galaxy. We found the upper limit to the fraction of GFs among short gamma-ray bursts with fluence above ˜5 × 10-7 erg cm-2 to be <8 per cent (95 per cent confidence level). Assuming that the number of active SGRs in nearby galaxies is proportional to their core-collapse supernova rate, we derived the one-sided 95 per cent upper limit to the rate of GFs with energy output similar to the GF from SGR 1806-20 to be (0.6-1.2)× 10^{-4} Q_{46}^{-1.5} yr-1 per SGR, where Q46 is the GF energy output in 1046 erg.

  20. Color and magnitude dependence of galaxy clustering

    NASA Astrophysics Data System (ADS)

    Müller, Volker

    2016-10-01

    A quantitative study of the clustering properties of galaxies in the cosmic web as a function of absolute magnitude and colour is presented using the SDSS Data Release 7 galaxy redshift survey. We compare our results with mock galaxy samples obtained with four different semi-analytical models of galaxy formation imposed on the merger trees of the Millenium simulation.

  1. Carbon monoxide emission from small galaxies

    NASA Technical Reports Server (NTRS)

    Thronson, Harley A., Jr.; Bally, John

    1987-01-01

    A search was conducted for J = 1 yields 0 CO emission from 22 galaxies, detecting half, as part of a survey to study star formation in small to medium size galaxies. Although substantial variation was found in the star formation efficiencies of the sample galaxies, there is no apparent systematic trend with galaxy size.

  2. A low-luminosity type-1 QSO sample . IV. Molecular gas contents and conditions of star formation in three nearby Seyfert galaxies

    NASA Astrophysics Data System (ADS)

    Moser, Lydia; Krips, Melanie; Busch, Gerold; Scharwächter, Julia; König, Sabine; Eckart, Andreas; Smajić, Semir; García-Marin, Macarena; Valencia-S., Mónica; Fischer, Sebastian; Dierkes, Jens

    2016-03-01

    We present a pilot study of ~3'' resolution observations of low CO transitions with the Submillimeter Array in three nearby Seyfert galaxies, which are part of the low-luminosity quasi-stellar object (LLQSOs) sample consisting of 99 nearby (z = 0.06) type-1 active galactic nuclei (AGN) taken from the Hamburg/ESO quasi-stellar object (QSO) survey. Two sources were observed in 12CO(2-1) and 13CO(2-1) and the third in 12CO(3-2) and HCO+(4-3). None of the sources is detected in continuum emission. More than 80% of the 12CO detected molecular gas is concentrated within a diameter (FWHM) < 1.8 kpc. 13CO is tentatively detected, while HCO+ emission could not be detected. All three objects show indications of a kinematically decoupled central unresolved molecular gas component. The molecular gas masses of the three galaxies are in the range Mmol = (0.7-8.7) × 109M⊙. We give lower limits for the dynamical masses of Mdyn> 1.5 × 109M⊙ and for the dust masses of Mdust> 1.6 × 106M⊙. The R21 = 12CO/13CO(2-1) line luminosity ratios show Galactic values of R21 ~ 5-7 in the outskirts and R21 ≳ 20 in the central region, similar to starbursts and (ultra)luminous infrared galaxies ((U)LIRGs; i.e. LIRGs and ULIRGs), implying higher temperatures and stronger turbulence. All three sources show indications of 12CO(2-1)/12CO(1-0) ratios of ~0.5, suggesting a cold or diffuse gas phase. Strikingly, the 12CO(3-2)/(1-0) ratio of ~1 also indicates a higher excited phase. Since these galaxies have high infrared luminosities of LIR ≥ 1011L⊙ and seem to contain a circumnuclear starburst with minimum surface densities of gas and star formation rate (SFR) around Σmol = 50-550 M⊙pc-2 and ΣSFR = 1.1-3.1 M⊙ kpc-2 yr-1, we conclude that the interstellar medium in the centers of these LIRG Seyferts is strongly affected by violent star formation and better described by the ULIRG mass conversion factor.

  3. A Magellan  M2FS Spectroscopic Survey of Galaxies at 5.5 < z < 6.8: Program Overview and a Sample of the Brightest Lyα Emitters

    NASA Astrophysics Data System (ADS)

    Jiang, Linhua; Shen, Yue; Bian, Fuyan; Zheng, Zhen-Ya; Wu, Jin; Oyarzún, Grecco A.; Blanc, Guillermo A.; Fan, Xiaohui; Ho, Luis C.; Infante, Leopoldo; Wang, Ran; Wu, Xue-Bing; Mateo, Mario; Bailey, John I., III; Crane, Jeffrey D.; Olszewski, Edward W.; Shectman, Stephen; Thompson, Ian; Walker, Matthew G.

    2017-09-01

    We present a spectroscopic survey of high-redshift, luminous galaxies over four square degrees on the sky, aiming to build a large and homogeneous sample of Lyα emitters (LAEs) at z≈ 5.7 and 6.5, and Lyman-break galaxies (LBGs) at 5.5< z< 6.8. The fields that we choose to observe are well studied, such as by the Subaru XMM-Newton Deep Survey and COSMOS. They have deep optical imaging data in a series of broad and narrow bands, allowing for the efficient selection of galaxy candidates. Spectroscopic observations are being carried out using the multi-object spectrograph M2FS on the Magellan Clay telescope. M2FS is efficient enough to identify high-redshift galaxies, owing to its 256 optical fibers deployed over a circular field of view 30\\prime in diameter. We have observed ∼2.5 square degrees. When the program is completed, we expect to identify more than 400 bright LAEs at z≈ 5.7 and 6.5, and a substantial number of LBGs at z≥slant 6. This unique sample will be used to study a variety of galaxy properties and to search for large protoclusters. Furthermore, the statistical properties of these galaxies will be used to probe cosmic reionization. We describe the motivation, program design, target selection, and M2FS observations. We also outline our science goals, and present a sample of the brightest LAEs at z≈ 5.7 and 6.5. This sample contains 32 LAEs with Lyα luminosities higher than 1043 erg s‑1. A few of them reach ≥3 × 1043 erg s‑1, comparable to the two most luminous LAEs known at z≥slant 6, “CR7” and “COLA1.” These LAEs provide ideal targets to study extreme galaxies in the distant universe.

  4. Erratum: ``Far-Infrared Photometry of a Statistical Sample of Late-Type Virgo Cluster Galaxies'' (ApJS, 139, 37 [2002])

    NASA Astrophysics Data System (ADS)

    Tuffs, Richard J.; Popescu, Cristina C.; Pierini, Daniele; Völk, Heinrich J.; Hippelein, Hans; Leech, Kieron; Metcalfe, Leo; Heinrichsen, Ingolf; Xu, Cong

    2002-06-01

    The legends for Figures 9 and 10 were switched. The legend for Figure 9 should read: ``Uncorrected χ2 values derived from fitting the Gaussian models to the maps vs. the corresponding flux densities at 60 μm obtained from integrating the model fit to infinity. The data were plotted as diamonds, except for those galaxies for which the model was an imperfect fit to the data, which were plotted as crosses. The solid line rising for F60>1.5 Jy represents the linear correlations between flux and χ2, as a result of systematic errors due to the oversampling in cross-scan direction. For faint flux densities χ2 is dominated by systematic errors, producing a clumpy distribution at the left-hand side of the plot, with a lower envelope, which we traced by a solid line to guide the eyes.'' The legend for Figure 10 should read: ``Model fits to the observed brightness profiles of all the Virgo galaxies from our sample (except for the interacting system VCC 1673/VCC 1676; see § 6.2.4). Statistical uncertainties for selected map pixels near the extremities and center of the scans are indicated by the 3 σ error bars. The legend is as in Fig. 8.'' In addition, the references to Figures 9 and 10 in the main text should be interchanged. The Press sincerely regrets this error.

  5. Brightest Cluster Galaxy Identification

    NASA Astrophysics Data System (ADS)

    Leisman, Luke; Haarsma, D. B.; Sebald, D. A.; ACCEPT Team

    2011-01-01

    Brightest cluster galaxies (BCGs) play an important role in several fields of astronomical research. The literature includes many different methods and criteria for identifying the BCG in the cluster, such as choosing the brightest galaxy, the galaxy nearest the X-ray peak, or the galaxy with the most extended profile. Here we examine a sample of 75 clusters from the Archive of Chandra Cluster Entropy Profile Tables (ACCEPT) and the Sloan Digital Sky Survey (SDSS), measuring masked magnitudes and profiles for BCG candidates in each cluster. We first identified galaxies by hand; in 15% of clusters at least one team member selected a different galaxy than the others.We also applied 6 other identification methods to the ACCEPT sample; in 30% of clusters at least one of these methods selected a different galaxy than the other methods. We then developed an algorithm that weighs brightness, profile, and proximity to the X-ray peak and centroid. This algorithm incorporates the advantages of by-hand identification (weighing multiple properties) and automated selection (repeatable and consistent). The BCG population chosen by the algorithm is more uniform in its properties than populations selected by other methods, particularly in the relation between absolute magnitude (a proxy for galaxy mass) and average gas temperature (a proxy for cluster mass). This work supported by a Barry M. Goldwater Scholarship and a Sid Jansma Summer Research Fellowship.

  6. Radio-Excess IRAS Galaxies. II. Host Galaxies

    NASA Astrophysics Data System (ADS)

    Drake, Catherine L.; McGregor, Peter J.; Dopita, Michael A.

    2004-09-01

    This is the second of a series of papers studying a sample of radio-excess IRAS galaxies. These galaxies have radio emission in excess of that expected due to star formation, but largely fall between the traditional categories of radio-loud and radio-quiet active galaxies. R-band images of the hosts of far-infrared (FIR)-luminous radio-excess galaxies are presented and analyzed. The hosts of the FIR-luminous radio-excess galaxies are luminous galaxies, on average 0.8 mag brighter than M*R. Their optical luminosities and morphologies are similar to comparison samples of radio-loud compact steep-spectrum and gigahertz peaked-spectrum sources and extended radio galaxies. We find a similar fraction of galaxies in our sample (~70%) with companions or distorted morphologies as in radio-loud comparison samples. This is consistent with radio activity being associated with tidal interaction. The majority (65%) of the FIR-luminous radio-excess galaxies have radio source sizes that are smaller than the optical host by more than an order of magnitude. These compact radio sources may be young precursors to classical radio galaxies or a different population of radio sources, possibly confined by the host interstellar medium. The host galaxy types were determined by analysis of the surface brightness distributions. The elliptical hosts have effective surface brightnesses and radii consistent with known ellipticals but inconsistent with a population of brightest cluster galaxies. Thus, it is unlikely these objects are the precursors of FR I radio galaxies. The disk hosts have smaller sizes and low radio excesses. However, they have a range of radio source sizes, which is not expected if they are radio-``loud'' Seyfert galaxies.

  7. Extragalactic distance scale derived from ''sosie'' galaxies. I. Distances of 167 galaxies which are sosies of 14 nearby galaxies

    SciTech Connect

    Bottinelli; Gouguenheim, L.; Paturel, G.; de Vaucouleurs, G.

    1985-11-01

    The method of ''sosie'' galaxies is applied to a large sample of galaxies extracted from the BGP catalog of H I line data and the Second Reference Catalogue of Bright Galaxies. The ''sosies'' of 14 calibrating galaxies (primary calibrators and galaxies in the nearest groups) are defined as those having the same parameters, either (1) morphological type T, axis ratio R, and maximum rotation velocity V/sub M/ or (2) T, R, and luminosity index ..lambda../sub c/.

  8. THE ATACAMA COSMOLOGY TELESCOPE: DYNAMICAL MASSES AND SCALING RELATIONS FOR A SAMPLE OF MASSIVE SUNYAEV-ZEL'DOVICH EFFECT SELECTED GALAXY CLUSTERS {sup ,}

    SciTech Connect

    Sifon, Cristobal; Barrientos, L. Felipe; Gonzalez, Jorge; Infante, Leopoldo; Duenner, Rolando; Menanteau, Felipe; Hughes, John P.; Baker, Andrew J.; Hasselfield, Matthew; Marriage, Tobias A.; Crichton, Devin; Gralla, Megan B.; Addison, Graeme E.; Dunkley, Joanna; Battaglia, Nick; Bond, J. Richard; Hajian, Amir; Das, Sudeep; Devlin, Mark J.; Hilton, Matt; and others

    2013-07-20

    We present the first dynamical mass estimates and scaling relations for a sample of Sunyaev-Zel'dovich effect (SZE) selected galaxy clusters. The sample consists of 16 massive clusters detected with the Atacama Cosmology Telescope (ACT) over a 455 deg{sup 2} area of the southern sky. Deep multi-object spectroscopic observations were taken to secure intermediate-resolution (R {approx} 700-800) spectra and redshifts for Almost-Equal-To 60 member galaxies on average per cluster. The dynamical masses M{sub 200c} of the clusters have been calculated using simulation-based scaling relations between velocity dispersion and mass. The sample has a median redshift z = 0.50 and a median mass M{sub 200c}{approx_equal}12 Multiplication-Sign 10{sup 14} h{sub 70}{sup -1} M{sub sun} with a lower limit M{sub 200c}{approx_equal}6 Multiplication-Sign 10{sup 14} h{sub 70}{sup -1} M{sub sun}, consistent with the expectations for the ACT southern sky survey. These masses are compared to the ACT SZE properties of the sample, specifically, the match-filtered central SZE amplitude y{sub 0}-tilde, the central Compton parameter y{sub 0}, and the integrated Compton signal Y{sub 200c}, which we use to derive SZE-mass scaling relations. All SZE estimators correlate with dynamical mass with low intrinsic scatter ({approx}< 20%), in agreement with numerical simulations. We explore the effects of various systematic effects on these scaling relations, including the correlation between observables and the influence of dynamically disturbed clusters. Using the three-dimensional information available, we divide the sample into relaxed and disturbed clusters and find that {approx}50% of the clusters are disturbed. There are hints that disturbed systems might bias the scaling relations, but given the current sample sizes, these differences are not significant; further studies including more clusters are required to assess the impact of these clusters on the scaling relations.

  9. Recent Galaxy Mergers and Residual Star Formation of Red Sequence Galaxies in Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Sheen, Yun-Kyeong; Yi, Sukyoung K.; Ree, Chang H.; Jaffé, Yara; Demarco, Ricardo; Treister, Ezequiel

    2016-08-01

    This study explored the Galaxy Evolution Explorer ultraviolet (UV) properties of optical red sequence galaxies in four rich Abell clusters at z≤slant 0.1. In particular, we tried to find a hint of merger-induced recent star formation (RSF) in red sequence galaxies. Using the NUV - r\\prime colors of the galaxies, RSF fractions were derived based on various criteria for post-merger galaxies and normal galaxies. Following k-correction, about 36% of the post-merger galaxies were classified as RSF galaxies with a conservative criterion (NUV - r\\prime ≤slant 5), and that number was doubled (˜72%) when using a generous criterion (NUV - r\\prime ≤slant 5.4). The trend was the same when we restricted the sample to galaxies within 0.5 × R 200. Post-merger galaxies with strong UV emission showed more violent, asymmetric features in the deep optical images. The RSF fractions did not show any trend along the clustocentric distance within R 200. We performed a Dressler-Shectman test to check whether the RSF galaxies had any correlation with the substructures in the galaxy clusters. Within R 200 of each cluster, the RSF galaxies did not appear to be preferentially related to the clusters’ substructures. Our results suggested that only 30% of RSF red sequence galaxies show morphological hints of recent galaxy mergers. This implies that internal processes (e.g., stellar mass loss or hot gas cooling) for the supply of cold gas to early-type galaxies may play a significant role in the residual star formation of early-type galaxies at a recent epoch.

  10. MULTIPLE GALAXY COLLISIONS

    NASA Technical Reports Server (NTRS)

    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.)

  11. Star formation enhancement characteristics in interacting galaxies

    NASA Astrophysics Data System (ADS)

    Zaragoza-Cardiel, J.; Beckman, J. E.; Font, J.; Camps-Fariña, A.; García-Lorenzo, B.; Erroz-Ferrer, S.

    2015-02-01

    We have observed 12 interacting galaxies using the Fabry-Perot interferometer GHαFaS (Galaxy Hα Fabry-Perot system) on the 4.2m William Herschel Telescope (La Palma). We have extracted the physical properties (sizes, Hα luminosity and velocity dispersion) of 236 HII regions for the full sample of interacting galaxies. We have derived the physical properties of 664 HII regions for a sample of 28 isolated galaxies observed with the same instrument in order to compare both populations of HII regions, finding that there are brighter and denser star forming regions in the interacting galaxies compared with the isolated galaxies sample.

  12. Size Bias in Galaxy Surveys

    NASA Astrophysics Data System (ADS)

    Schmidt, Fabian; Rozo, Eduardo; Dodelson, Scott; Hui, Lam; Sheldon, Erin

    2009-07-01

    Only certain galaxies are included in surveys: those bright and large enough to be detectable as extended sources. Because gravitational lensing can make galaxies appear both brighter and larger, the presence of foreground inhomogeneities can scatter galaxies across not only magnitude cuts but also size cuts, changing the statistical properties of the resulting catalog. Here we explore this size bias and how it combines with magnification bias to affect galaxy statistics. We demonstrate that photometric galaxy samples from current and upcoming surveys can be even more affected by size bias than by magnification bias.

  13. (Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. II. The spatial extent of the radio-emitting regions

    NASA Astrophysics Data System (ADS)

    Miettinen, O.; Novak, M.; Smolčić, V.; Schinnerer, E.; Sargent, M.; Murphy, E. J.; Aravena, M.; Bondi, M.; Carilli, C. L.; Karim, A.; Salvato, M.; Zamorani, G.

    2015-12-01

    Radio emission at centimetre wavelengths from highly star-forming galaxies, like submillimetre galaxies (SMGs), is dominated by synchrotron radiation arising from supernova activity. Hence, radio continuum imaging has the potential to determine the spatial extent of star formation in these types of galaxies. Using deep, high-resolution (1σ = 2.3 μJy beam-1; 0.75 arcsec) centimetre radio-continuum observations taken by the Karl G. Jansky Very Large Array (VLA)-COSMOS 3 GHz Large Project, we studied the radio-emitting sizes of a flux-limited sample of SMGs in the COSMOS field. The target SMGs were originally discovered in a 1.1 mm continuum survey carried out with the AzTEC bolometer, and followed up with higher resolution interferometric (sub)millimetre continuum observations. Of the 39 SMGs studied here, 3 GHz emission was detected towards 18 of them (~46 ± 11%) with signal-to-noise ratios in the range of S/N = 4.2-37.4. Towards four SMGs (AzTEC2, 5, 8, and 11), we detected two separate 3 GHz sources with projected separations of ~1''&dotbelow;5-6''&dotbelow;6, but they might be physically related in only one or two cases (AzTEC2 and 11). Using two-dimensional elliptical Gaussian fits, we derived a median deconvolved major axis FWHM size of 0''&dotbelow;54±0''&dotbelow;11 for our 18 SMGs detected at 3 GHz. For the 15 SMGs with known redshift we derived a median linear major axis FWHM of 4.2 ± 0.9 kpc. No clear correlation was found between the radio-emitting size and the 3 GHz or submm flux density, or the redshift of the SMG. However, there is a hint of larger radio sizes at z ~ 2.5-5 compared to lower redshifts. The sizes we derived are consistent with previous SMG sizes measured at 1.4 GHz and in mid-J CO emission, but significantly larger than those seen in the (sub)mm continuum emission (typically probing the rest-frame far-infrared with median FWHM sizes of only ~1.5-2.5 kpc). One possible scenario is that SMGs have i) an extended gas component with a

  14. The TANGO Project: Thorough ANalysis of radio-Galaxies Observations

    NASA Astrophysics Data System (ADS)

    Ocaña Flaquer, Breezy; Leon Tanne, Stephane; Combes, Francoise; Lim, Jeremy

    2010-05-01

    We present a sample of radio galaxies selected only on the basis of radio continuum emission and we confirm that these galaxies have lower molecular gas mass than other elliptical galaxies with different selection criteria.

  15. Structure and stellar content of dwarf galaxies. VII. B and R photometry of 25 southern field dwarfs and a disk parameter analysis of the complete sample of nearby irregulars

    NASA Astrophysics Data System (ADS)

    Parodi, B. R.; Barazza, F. D.; Binggeli, B.

    2002-06-01

    We present B and R band surface photometry of 25 Southern field dwarf galaxies within a distance of 10 Mpc. For each galaxy we give the essential model-free photometric parameters and, by fitting exponentials to the surface brightness profiles, the central extrapolated surface brightness and the exponential scale length, in both colour bands. Surface brightness and colour profiles are shown. One of the objects, a very faint dwarf elliptical in the vicinity of NGC 2784, has been discovered in the course of this work. Drawing on the data from this and all previous papers of this series, we construct a complete sample of 72 late-type (``irregular'') dwarf galaxies in nearby groups and the field within the 10 Mpc volume, to study the exponential-disk parameter relations of these galaxies with respect to galaxy environment. We confirm our previous finding of statistically lower scale lengths/higher central surface brightnesses for field and group galaxies as compared to cluster galaxies. However, using a clear-cut definition of ``group'' versus ``field'' environment, we find no significant difference in the photometric structure of group and field irregulars. A difference in the star formation history may partly account for this structure-environment relation: for a given luminosity cluster dwarfs are on average redder than field and group galaxies. We also report evidence for the colour gradients of dwarf irregulars being roughly inversely proportional to the disk scale lengths. Supplementing our photometric data with kinematic data from the literature, we study possible relations with kinematic properties of the inner disk. Applying the dark matter scaling relations for a Burkert halo we show that for field and group galaxies of a given luminosity faster-than-mean disk rotational velocities at a radius of about two scale lengths are correlated with larger-than-mean disk scale lengths. Based on observations collected at the European Southern Observatory, La Silla

  16. DISCOVERY OF ULTRA-FAST OUTFLOWS IN A SAMPLE OF BROAD-LINE RADIO GALAXIES OBSERVED WITH SUZAKU

    SciTech Connect

    Tombesi, F.; Sambruna, R. M.; Mushotzky, R. F.; Braito, V.; Ballo, L.; Cappi, M.

    2010-08-10

    We present the results of a uniform and systematic search for blueshifted Fe K absorption lines in the X-ray spectra of five bright broad-line radio galaxies observed with Suzaku. We detect, for the first time in radio-loud active galactic nuclei (AGNs) at X-rays, several absorption lines at energies greater than 7 keV in three out of five sources, namely, 3C 111, 3C 120, and 3C 390.3. The lines are detected with high significance according to both the F-test and extensive Monte Carlo simulations. Their likely interpretation as blueshifted Fe XXV and Fe XXVI K-shell resonance lines implies an origin from highly ionized gas outflowing with mildly relativistic velocities, in the range v {approx_equal} 0.04-0.15c. A fit with specific photoionization models gives ionization parameters in the range log {xi} {approx_equal} 4-5.6 erg s{sup -1} cm and column densities of N {sub H} {approx_equal} 10{sup 22}-10{sup 23} cm{sup -2}. These characteristics are very similar to those of the ultra-fast outflows (UFOs) previously observed in radio-quiet AGNs. Their estimated location within {approx}0.01-0.3 pc of the central super-massive black hole suggests a likely origin related with accretion disk winds/outflows. Depending on the absorber covering fraction, the mass outflow rate of these UFOs can be comparable to the accretion rate and their kinetic power can correspond to a significant fraction of the bolometric luminosity and is comparable to their typical jet power. Therefore, these UFOs can play a significant role in the expected feedback from the AGN to the surrounding environment and can give us further clues on the relation between the accretion disk and the formation of winds/jets in both radio-quiet and radio-loud AGNs.

  17. Discovery of Ultra-fast Outflows in a Sample of Broad-line Radio Galaxies Observed with Suzaku

    NASA Astrophysics Data System (ADS)

    Tombesi, F.; Sambruna, R. M.; Reeves, J. N.; Braito, V.; Ballo, L.; Gofford, J.; Cappi, M.; Mushotzky, R. F.

    2010-08-01

    We present the results of a uniform and systematic search for blueshifted Fe K absorption lines in the X-ray spectra of five bright broad-line radio galaxies observed with Suzaku. We detect, for the first time in radio-loud active galactic nuclei (AGNs) at X-rays, several absorption lines at energies greater than 7 keV in three out of five sources, namely, 3C 111, 3C 120, and 3C 390.3. The lines are detected with high significance according to both the F-test and extensive Monte Carlo simulations. Their likely interpretation as blueshifted Fe XXV and Fe XXVI K-shell resonance lines implies an origin from highly ionized gas outflowing with mildly relativistic velocities, in the range v ~= 0.04-0.15c. A fit with specific photoionization models gives ionization parameters in the range log ξ ~= 4-5.6 erg s-1 cm and column densities of N H ~= 1022-1023 cm-2. These characteristics are very similar to those of the ultra-fast outflows (UFOs) previously observed in radio-quiet AGNs. Their estimated location within ~0.01-0.3 pc of the central super-massive black hole suggests a likely origin related with accretion disk winds/outflows. Depending on the absorber covering fraction, the mass outflow rate of these UFOs can be comparable to the accretion rate and their kinetic power can correspond to a significant fraction of the bolometric luminosity and is comparable to their typical jet power. Therefore, these UFOs can play a significant role in the expected feedback from the AGN to the surrounding environment and can give us further clues on the relation between the accretion disk and the formation of winds/jets in both radio-quiet and radio-loud AGNs.

  18. Isolated Galaxies and Isolated Satellite Systems

    NASA Astrophysics Data System (ADS)

    Ann, H. B.; Park, C.; Choi, Y. Y.

    2010-10-01

    We search for isolated galaxies using a volume-limited sample of galaxies with 0.02 < z < 0.04742 from SDSS DR7 supplemented by bright galaxies. We devise a diagnostic tool to select isolated galaxies in different environments using the projected separation (rp) normalized by the virial radius of the nearest neighbor (rvir,nei) and the local background density. We find that the isolation condition of rp > rvir,nei and ρ < ρbar well segregates the CIG galaxies. We confirm the morphology conformity between the host and their satellites, which suggests the importance to galaxy evolution of hydrodynamic interactions among galaxies within their virial radii.

  19. UPDATED NEARBY GALAXY CATALOG

    SciTech Connect

    Karachentsev, Igor D.; Makarov, Dmitry I.; Kaisina, Elena I.

    2013-04-15

    We present an all-sky catalog of 869 nearby galaxies having individual distance estimates within 11 Mpc or corrected radial velocities V{sub LG} < 600 km s{sup -1}. The catalog is a renewed and expanded version of the Catalog of Neighboring Galaxies by Karachentsev et al. It collects data on the following galaxy observables: angular diameters, apparent magnitudes in far-UV, B, and K{sub s} bands, H{alpha} and H I fluxes, morphological types, H I-line widths, radial velocities, and distance estimates. In this Local Volume (LV) sample, 108 dwarf galaxies still remain without measured radial velocities. The catalog yields also calculated global galaxy parameters: linear Holmberg diameter, absolute B magnitude, surface brightness, H I mass, stellar mass estimated via K-band luminosity, H I rotational velocity corrected for galaxy inclination, indicative mass within the Holmberg radius, and three kinds of ''tidal index,'' which quantify the local density environment. The catalog is supplemented with data based on the local galaxies, which presents their optical and available H{alpha} images, as well as other services. We briefly discuss the Hubble flow within the LV and different scaling relations that characterize galaxy structure and global star formation in them. We also trace the behavior of the mean stellar mass density, H I-mass density, and star formation rate density within the volume considered.

  20. Superluminous Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Ogle, Patrick M.; Lanz, Lauranne; Nader, Cyril; Helou, George

    2016-02-01

    We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster galaxies, with r-band monochromatic luminosity Lr = 8-14L* (4.3-7.5 × 1044 erg s-1). These super spiral galaxies are also giant and massive, with diameter D = 57-134 kpc and stellar mass Mstars = 0.3-3.4 × 1011M⊙. We find 53 super spirals out of a complete sample of 1616 SDSS galaxies with redshift z < 0.3 and Lr > 8L*. The closest example is found at z = 0.089. We use existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS and Wide-field Infrared Survey Explorer colors are consistent with normal star-forming spirals on the blue sequence. However, the extreme masses and rapid SFRs of 5-65 M⊙ yr-1 place super spirals in a sparsely populated region of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a diverse range of environments, from isolation to cluster centers. We find four super spiral galaxy systems that are late-stage major mergers—a possible clue to their formation. We suggest that super spirals are a remnant population of unquenched, massive disk galaxies. They may eventually become massive lenticular galaxies after they are cut off from their gas supply and their disks fade.

  1. Galaxy And Mass Assembly (GAMA) blended spectra catalogue: strong galaxy-galaxy lens and occulting galaxy pair candidates

    NASA Astrophysics Data System (ADS)

    Holwerda, B. W.; Baldry, I. K.; Alpaslan, M.; Bauer, A.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Cluver, M. E.; Conselice, C.; Driver, S. P.; Hopkins, A. M.; Jones, D. H.; López-Sánchez, Á. R.; Loveday, J.; Meyer, M. J.; Moffett, A.

    2015-06-01

    We present the catalogue of blended galaxy spectra from the Galaxy And Mass Assembly (GAMA) survey. These are cases where light from two galaxies are significantly detected in a single GAMA fibre. Galaxy pairs identified from their blended spectrum fall into two principal classes: they are either strong lenses, a passive galaxy lensing an emission-line galaxy; or occulting galaxies, serendipitous overlaps of two galaxies, of any type. Blended spectra can thus be used to reliably identify strong lenses for follow-up observations (high-resolution imaging) and occulting pairs, especially those that are a late-type partly obscuring an early-type galaxy which are of interest for the study of dust content of spiral and irregular galaxies. The GAMA survey setup and its AUTOZ automated redshift determination were used to identify candidate blended galaxy spectra from the cross-correlation peaks. We identify 280 blended spectra with a minimum velocity separation of 600 km s-1, of which 104 are lens pair candidates, 71 emission-line-passive pairs, 78 are pairs of emission-line galaxies and 27 are pairs of galaxies with passive spectra. We have visually inspected the candidates in the Sloan Digital Sky Survey (SDSS) and Kilo Degree Survey (KiDS) images. Many blended objects are ellipticals with blue fuzz (Ef in our classification). These latter `Ef' classifications are candidates for possible strong lenses, massive ellipticals with an emission-line galaxy in one or more lensed images. The GAMA lens and occulting galaxy candidate samples are similar in size to those identified in the entire SDSS. This blended spectrum sample stands as a testament of the power of this highly complete, second-largest spectroscopic survey in existence and offers the possibility to expand e.g. strong gravitational lens surveys.

  2. Are long gamma-ray bursts biased tracers of star formation? Clues from the host galaxies of the Swift/BAT6 complete sample of bright LGRBs. II. Star formation rates and metallicities at z < 1

    NASA Astrophysics Data System (ADS)

    Japelj, J.; Vergani, S. D.; Salvaterra, R.; D'Avanzo, P.; Mannucci, F.; Fernandez-Soto, A.; Boissier, S.; Hunt, L. K.; Atek, H.; Rodríguez-Muñoz, L.; Scodeggio, M.; Cristiani, S.; Le Floc'h, E.; Flores, H.; Gallego, J.; Ghirlanda, G.; Gomboc, A.; Hammer, F.; Perley, D. A.; Pescalli, A.; Petitjean, P.; Puech, M.; Rafelski, M.; Tagliaferri, G.

    2016-05-01

    Aims: Long gamma-ray bursts (LGRBs) are associated with the deaths of massive stars and might therefore be a potentially powerful tool for tracing cosmic star formation. However, especially at low redshifts (z< 1.5) LGRBs seem to prefer particular types of environment. Our aim is to study the host galaxies of a complete sample of bright LGRBs to investigate the effect of the environment on GRB formation. Methods: We studied host galaxy spectra of the Swift/BAT6 complete sample of 14 z< 1 bright LGRBs. We used the detected nebular emission lines to measure the dust extinction, star formation rate (SFR), and nebular metallicity (Z) of the hosts and supplemented the data set with previously measured stellar masses M⋆. The distributions of the obtained properties and their interrelations (e.g. mass-metallicity and SFR-M⋆ relations) are compared to samples of field star-forming galaxies. Results: We find that LGRB hosts at z< 1 have on average lower SFRs than if they were direct star formation tracers. By directly comparing metallicity distributions of LGRB hosts and star-forming galaxies, we find a good match between the two populations up to 12 +log ≤ft( frac{OHright)} 8.4-8.5, after which the paucity of metal-rich LGRB hosts becomes apparent. The LGRB host galaxies of our complete sample are consistent with the mass-metallicity relation at similar mean redshift and stellar masses. The cutoff against high metallicities (and high masses) can explain the low SFR values of LGRB hosts. We find a hint of an increased incidence of starburst galaxies in the Swift/BAT6 z< 1 sample with respect to that of a field star-forming population. Given that the SFRs are low on average, the latter is ascribed to low stellar masses. Nevertheless, the limits on the completeness and metallicity availability of current surveys, coupled with the limited number of LGRB host galaxies, prevents us from investigating more quantitatively whether the starburst incidence is such as expected

  3. Joint Analysis of Cluster Observations. II. Chandra/XMM-Newton X-Ray and Weak Lensing Scaling Relations for a Sample of 50 Rich Clusters of Galaxies

    NASA Astrophysics Data System (ADS)

    Mahdavi, Andisheh; Hoekstra, Henk; Babul, Arif; Bildfell, Chris; Jeltema, Tesla; Henry, J. Patrick

    2013-04-01

    We present a study of multiwavelength X-ray and weak lensing scaling relations for a sample of 50 clusters of galaxies. Our analysis combines Chandra and XMM-Newton data using an energy-dependent cross-calibration. After considering a number of scaling relations, we find that gas mass is the most robust estimator of weak lensing mass, yielding 15% ± 6% intrinsic scatter at r500WL (the pseudo-pressure YX yields a consistent scatter of 22% ± 5%). The scatter does not change when measured within a fixed physical radius of 1 Mpc. Clusters with small brightest cluster galaxy (BCG) to X-ray peak offsets constitute a very regular population whose members have the same gas mass fractions and whose even smaller (<10%) deviations from regularity can be ascribed to line of sight geometrical effects alone. Cool-core clusters, while a somewhat different population, also show the same (<10%) scatter in the gas mass-lensing mass relation. There is a good correlation and a hint of bimodality in the plane defined by BCG offset and central entropy (or central cooling time). The pseudo-pressure YX does not discriminate between the more relaxed and less relaxed populations, making it perhaps the more even-handed mass proxy for surveys. Overall, hydrostatic masses underestimate weak lensing masses by 10% on the average at r500WL; but cool-core clusters are consistent with no bias, while non-cool-core clusters have a large and constant 15%-20% bias between r2500WL and r500WL, in agreement with N-body simulations incorporating unthermalized gas. For non-cool-core clusters, the bias correlates well with BCG ellipticity. We also examine centroid shift variance and power ratios to quantify substructure; these quantities do not correlate with residuals in the scaling relations. Individual clusters have for the most part forgotten the source of their departures from self-similarity.

  4. Kinematics of Metal-poor Stars in the Galaxy. III. Formation of the Stellar Halo and Thick Disk as Revealed from a Large Sample of Nonkinematically Selected Stars

    NASA Astrophysics Data System (ADS)

    Chiba, Masashi; Beers, Timothy C.

    2000-06-01

    We present a detailed analysis of the space motions of 1203 solar-neighborhood stars with metal abundances [Fe/H]<=-0.6, on the basis of a catalog, of metal-poor stars selected without kinematic bias recently revised and supplemented by Beers et al. This sample, having available proper motions, radial velocities, and distance estimates for stars with a wide range of metal abundances, is by far the largest such catalog to be assembled to date. We show that the stars in our sample with [Fe/H]<=-2.2, which likely represent a ``pure'' halo component, are characterized by a radially elongated velocity ellipsoid (σU,σV,σW)=(141+/-11, 106+/-9, 94+/-8) km s-1 and small prograde rotation =30 to 50 km s-1, consistent with previous analysis of this sample by Beers and Sommer-Larsen based on radial velocity information alone. In contrast to the previous analysis, we find a decrease in with increasing distance from the Galactic plane for stars that are likely to be members of the halo population (Δ/Δ|Z|=-52+/-6 km s-1 kpc-1), which may represent the signature of a dissipatively formed flattened inner halo. Unlike essentially all previous kinematically selected catalogs, the metal-poor stars in our sample exhibit a diverse distribution of orbital eccentricities, e, with no apparent correlation between [Fe/H] and e. This demonstrates, clearly and convincingly, that the evidence offered in 1962 by Eggen, Lynden-Bell, & Sandage for a rapid collapse of the Galaxy, an apparent correlation between the orbital eccentricity of halo stars with metallicity, is basically the result of their proper-motion selection bias. However, even in our nonkinematically selected sample, we have identified a small concentration of high-e stars at [Fe/H]~-1.7, which may originate, in part, from infalling gas during the early formation of the Galaxy. We find no evidence for an additional thick disk component for stellar abundances [Fe/H]<=-2.2. The kinematics of the intermediate

  5. Disks in elliptical galaxies

    SciTech Connect

    Rix, H.; White, S.D.M. )

    1990-10-01

    The abundance and strength of disk components in elliptical galaxies are investigated by studying the photometric properties of models containing a spheroidal r exp 1/4-law bulge and a weak exponential disk. Pointed isophotes are observed in a substantial fraction of elliptical galaxies. If these isophote distortions are interpreted in the framework of the present models, then the statistics of observed samples suggest that almost all radio-weak ellipticals could have disks containing roughly 20 percent of the light. It is shown that the E5 galaxy NGC 4660 has the photometric signatures of a disk containing a third of the light. 30 refs.

  6. VVDS-SWIRE. Clustering evolution from a spectroscopic sample of galaxies with redshift 0.2 < z < 2.1 selected from Spitzer IRAC 3.6 μm and 4.5 μm photometry

    NASA Astrophysics Data System (ADS)

    de la Torre, S.; Le Fèvre, O.; Arnouts, S.; Guzzo, L.; Farrah, D.; Iovino, A.; Lonsdale, C. J.; Meneux, B.; Oliver, S. J.; Pollo, A.; Waddington, I.; Bottini, D.; Fang, F.; Garilli, B.; Le Brun, V.; Maccagni, D.; Picat, J. P.; Scaramella, R.; Scodeggio, M.; Shupe, D.; Surace, J.; Tresse, L.; Vettolani, G.; Zanichelli, A.; Adami, C.; Bardelli, S.; Bolzonella, M.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; Foucaud, S.; Franzetti, P.; Gavignaud, I.; Ilbert, O.; Lamareille, F.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mazure, A.; Merighi, R.; Paltani, S.; Pellò, R.; Pozzetti, L.; Radovich, M.; Zamorani, G.; Zucca, E.; Bondi, M.; Bongiorno, A.; Brinchmann, J.; Cucciati, O.; Mellier, Y.; Merluzzi, P.; Temporin, S.; Vergani, D.; Walcher, C. J.

    2007-11-01

    Aims:By combining data from the VIMOS VLT Deep Survey (VVDS) with the Spitzer Wide-area InfraRed Extragalactic survey (SWIRE), we have built the currently largest spectroscopic sample of high redshift galaxies selected in the rest-frame near-infrared. We have obtained 2040 spectroscopic redshifts of galaxies with (m3.6)_AB < 21.5 at 3.6 μ m, and 1255 spectroscopic redshifts of galaxies with (m4.5)_AB < 21. These allow us to investigate the clustering evolution of galaxies selected via their rest-frame near-infrared luminosity in the redshift range 0.2 < z < 2.1. Methods: We use the projected two-point correlation function w_p(r_p) to study the three dimensional clustering properties of galaxies detected at 3.6 μ m and 4.5 μ m with the InfraRed Array Camera (IRAC) in the SWIRE survey with measured spectroscopic redshifts from the first epoch VVDS. We compare these properties to those of a larger sample of 16672 SWIRE galaxies for which we have accurate photometric redshifts in the same field. Results: We find that in the 3.6 μ m and 4.5 μ m flux limited samples, the apparent correlation length does not change from redshift ~2 to the present. The measured correlation lengths have a mean value of r0 ≃ 3.9±0.5 h-1 Mpc for the galaxies selected at 3.6 μ m and a mean value of r0 ≃ 4.4±0.5 h-1 Mpc for the galaxies selected at 4.5 μ m, across the whole redshift range explored. These values are larger than those typicaly found for I-band selected galaxies at I_AB < 24, for which r0 varies from 2.69 h-1 Mpc to 3.63 h-1 Mpc between z = 0.5 to z = 2.1. We find that the difference in correlation length between I-band and 3.6-4.5 μm selected samples decreases with increasing redshift, becoming comparable at z ≃ 1.5. We interpret this as evidence that galaxies with older stellar populations and galaxies actively forming stars reside in comparably over-dense environments at epochs earlier than z ≃ 1.5, supporting the recently reported flattening of the color

  7. Warm absorbers in X-rays (WAX), a comprehensive high-resolution grating spectral study of a sample of Seyfert Galaxies - II. Warm absorber dynamics and feedback to galaxies

    NASA Astrophysics Data System (ADS)

    Laha, Sibasish; Guainazzi, Matteo; Chakravorty, Susmita; Dewangan, Gulab C.; Kembhavi, Ajit K.

    2016-04-01

    This paper is a sequel to the extensive study of warm absorber (WA) in X-rays carried out using high-resolution grating spectral data from XMM-Newton satellite (WAX-I). Here we discuss the global dynamical properties as well as the energetics of the WA components detected in the WAX sample. The slope of WA density profile (n ∝ r-α) estimated from the linear regression slope of ionization parameter ξ and column density NH in the WAX sample is α = 1.236 ± 0.034. We find that the WA clouds possibly originate as a result of photoionized evaporation from the inner edge of the torus (torus wind). They can also originate in the cooling front of the shock generated by faster accretion disc outflows, the ultrafast outflows, impinging on to the interstellar medium or the torus. The acceleration mechanism for the WA is complex and neither radiatively driven wind nor MHD-driven wind scenario alone can describe the outflow acceleration. However, we find that radiative forces play a significant role in accelerating the WA through the soft X-ray absorption lines, and also with dust opacity. Given the large uncertainties in the distance and volume filling factor estimates of the WA, we conclude that the kinetic luminosity ĖK of WA may sometimes be large enough to yield significant feedback to the host galaxy. We find that the lowest ionization states carry the maximum mass outflow, and the sources with higher Fe M UTA absorption (15-17 Å) have more mass outflow rates.

  8. Properties of isolated disk galaxies

    NASA Astrophysics Data System (ADS)

    Varela, J.; Moles, M.; Márquez, I.; Galletta, G.; Masegosa, J.; Bettoni, D.

    2004-06-01

    We present a new sample of northern isolated galaxies, which are defined by the physical criterion that they were not affected by other galaxies in their evolution during the last few Gyr. To find them we used the logarithmic ratio, f, between inner and tidal forces acting upon the candidate galaxy by a possible perturber. The analysis of the distribution of the f-values for the galaxies in the Coma cluster lead us to adopt the criterion f ≤ -4.5 for isolated galaxies. The candidates were chosen from the CfA catalog of galaxies within the volume defined by cz ≤5000 km s-1, galactic latitude higher than 40o and declination ≥-2.5o. The selection of the sample, based on redshift values (when available), magnitudes and sizes of the candidate galaxies and possible perturbers present in the same field is discussed. The final list of selected isolated galaxies includes 203 objects from the initial 1706. The list contains only truly isolated galaxies in the sense defined, but it is by no means complete, since all the galaxies with possible companions under the f-criterion but with unknown redshift were discarded. We also selected a sample of perturbed galaxies comprised of all the disk galaxies from the initial list with companions (with known redshift) satisfying f ≥ -2 and \\Delta(cz) ≤500 km s-1; a total of 130 objects. The statistical comparison of both samples shows significant differences in morphology, sizes, masses, luminosities and color indices. Confirming previous results, we found that late spiral, Sc-type galaxies are, in particular, more frequent among isolated galaxies, whereas Lenticular galaxies are more abundant among perturbed galaxies. Isolated systems appear to be smaller, less luminous and bluer than interacting objects. We also found that bars are twice as frequent among perturbed galaxies compared to isolated galaxies, in particular for early Spirals and Lenticulars. The perturbed galaxies have higher LFIR/LB and Mmol/LB ratios, but the

  9. Lyman Alpha Galaxies and Galaxy Formation Scenarios

    NASA Astrophysics Data System (ADS)

    Rhoads, James; Malhotra, Sangeeta

    2005-08-01

    The Large Area Lyman Alpha survey has successfully identified the population of young Lyα emitting galaxies predicted over 35 years ago. High equivalent widths of Lyα in these sources suggest that they are a very young (age < 10^7 years), metal poor, population of stars, making them very interesting objects for understanding galaxy formation. With two nights of Magellan+IMACS time, we will obtain spectroscopic confirmation of 150-200 secure LALA sources at redshift z=4.5. Followup of a similar number of fainter Lyα candidates will characterize the completeness and weed out foreground emission line galaxies. The excellent match between wide-field capabilities of IMACS and the LALA survey makes this the most complete confirmation and characterization of the high redshift Lyα population yet. With our spectroscopic sample, we will: (1) Search for AGN among our sample- a few should be found if the AGN fraction is comparable to that in Lyman break galaxies. (2) Produce a high S/N coadded spectrum, where we will look for (a) HeII (1640Å) emission, which is an indicator of Pop III stars; and (b) ISM absorption lines, whose velocity offset relative to the Lyα emission is an indicator of galactic winds in these early starbursts. (3) Obtain a clean measurement of spatial correlations among Lyα galaxies, and thereby derive the halo mass, occupancy number, and duty cycle of Lyα galaxies, to see how they fit into the bigger picture of galaxy formation.

  10. HETDEX: Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Drory, Niv; Gebhardt, K.; Jogee, S.; Fabricius, M.; Greene, J.; HETDEX Collaboration

    2012-01-01

    The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) is a blind spectroscopic survey using the VIRUS instrument. VIRUS consists of 75 IFUs distributed across the 22-arcmin field of the upgraded 9.2-m HET. Each 50x50 arcsec IFU is made up of 448 1.5-arcsec fibers, and feeds a pair of spectrographs with a fixed bandpass of 350-550 nm and resolving power R 700. The IFUs have a fill-factor of 1/3 which will be filled-in by dithering. We cover 1/4.5 of our 300-square-degree main survey area with fibers. We reach m_AB 22.6 (21.5,20.7) at S/N 3 (5,10) per resolution element. With these limits, g 17 spiral galaxies will have S/N>3 per resolution element per fiber in the continuum to 2 effective radii, and emission line spectra to at least their optical radius. HETDEX will spatially resolve 4000 local galaxies to that limit without any pre-selection; an additional 9000 local galaxies will have spatially resolved spectroscopy beyond that limit. At g 19 we still obtain integrated galaxy spectra at S/N 10 per resolution element in the continuum. These spatially resolved absorption and emission spectra provide information on star formation, the state of the IGM, and stellar populations, as well as rotation curves for an unbiased galaxy sample unprecedented in size. Since a wealth of information about a galaxy's formation history is encoded in gradients across the galaxy, moving from single-fiber (SDSS-like) spectra to large samples of spatially resolved galaxy spectroscopy opens a new parameter space for future studies of galaxy formation.

  11. Accretion Properties of a Sample of Hard X-Ray (<60 keV) Selected Seyfert 1 Galaxies

    NASA Astrophysics Data System (ADS)

    Wang, J.; Mao, Y. F.; Wei, J. Y.

    2009-02-01

    We examine the accretion properties in a sample of 42 hard (3-60 keV) X-ray selected nearby broad-line active galactic nuclei (AGNs). The energy range in the sample is harder than that usually used in similar previous studies. These AGNs are mainly complied from the RXTE All Sky Survey, and complemented by the released INTEGRAL AGN catalog. The black hole masses, bolometric luminosities of AGN, and Eddington ratios are derived from their optical spectra in terms of the broad Hβ emission line. The tight correlation between the hard X-ray (3-20 keV) and bolometric/line luminosity is well identified in our sample. Also identified is a strong inverse Baldwin relationship of the Hβ emission line. In addition, all of these hard X-ray AGNs are biased toward luminous objects with a high Eddington ratio (mostly between 0.01 and 0.1) and a low column density (<1022 cm-2), which is most likely due to the selection effect of the surveys. The hard X-ray luminosity is consequently found to be strongly correlated with the black hole mass. We believe the sample completeness will be improved in the next few years by the ongoing Swift and the International Gamma-Ray Astrophysics Laboratory missions, and by the next advanced missions, such as NuSTAR, Simbol-X, and NeXT. Finally, the correlation between RFe (= optical Fe II/Hβ) and disk temperature as assessed by T vprop (L/L Edd)M -1 BH leads us to suggest that the strength of the Fe II emission is mainly determined by the shape of the ionizing spectrum.

  12. The environments of Markarian galaxies

    NASA Technical Reports Server (NTRS)

    Mackenty, John W.; Simpson, Caroline; Mclean, Brian

    1990-01-01

    The extensively studied Markarian sample of 1500 ultraviolet excess galaxies contains many Seyfert, starburst, and peculiar galaxies. Using the 20 minute V plates obtained for the construction of the Hubble Space Telescope Guide Star Catalog, the authors investigated the morphologies of the Markarian galaxies and the environments in which they are located. The relationship between the types of nuclear activity and the morphologies and environments of the Markarian galaxies is discussed. The authors conclude that the type of nuclear activity present in the galaxies of the Markarian sample is not dependent on either the morphology or the local environment of the galaxy. This is not to imply that nuclear activity per se is not influenced by the environment in which the nucleus is located. Rather the type of nuclear activity (at least in the Markarian population) does not appear to be determined by the environment.

  13. Galaxy and Mass Assembly (GAMA): ugriz galaxy luminosity functions

    NASA Astrophysics Data System (ADS)

    Loveday, J.; Norberg, P.; Baldry, I. K.; Driver, S. P.; Hopkins, A. M.; Peacock, J. A.; Bamford, S. P.; Liske, J.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Cameron, E.; Conselice, C. J.; Croom, S. M.; Frenk, C. S.; Gunawardhana, M.; Hill, D. T.; Jones, D. H.; Kelvin, L. S.; Kuijken, K.; Nichol, R. C.; Parkinson, H. R.; Phillipps, S.; Pimbblet, K. A.; Popescu, C. C.; Prescott, M.; Robotham, A. S. G.; Sharp, R. G.; Sutherland, W. J.; Taylor, E. N.; Thomas, D.; Tuffs, R. J.; van Kampen, E.; Wijesinghe, D.

    2012-02-01

    Galaxy and Mass Assembly (GAMA) is a project to study galaxy formation and evolution, combining imaging data from ultraviolet to radio with spectroscopic data from the AAOmega spectrograph on the Anglo-Australian Telescope. Using data from Phase 1 of GAMA, taken over three observing seasons, and correcting for various minor sources of incompleteness, we calculate galaxy luminosity functions (LFs) and their evolution in the ugriz passbands. At low redshift, z < 0.1, we find that blue galaxies, defined according to a magnitude-dependent but non-evolving colour cut, are reasonably well fitted over a range of more than 10 magnitudes by simple Schechter functions in all bands. Red galaxies, and the combined blue plus red sample, require double power-law Schechter functions to fit a dip in their LF faintwards of the characteristic magnitude M* before a steepening faint end. This upturn is at least partly due to dust-reddened disc galaxies. We measure the evolution of the galaxy LF over the redshift range 0.002 < z < 0.5 both by using a parametric fit and by measuring binned LFs in redshift slices. The characteristic luminosity L* is found to increase with redshift in all bands, with red galaxies showing stronger luminosity evolution than blue galaxies. The comoving number density of blue galaxies increases with redshift, while that of red galaxies decreases, consistent with prevailing movement from blue cloud to red sequence. As well as being more numerous at higher redshift, blue galaxies also dominate the overall luminosity density beyond redshifts z≃ 0.2. At lower redshifts, the luminosity density is dominated by red galaxies in the riz bands, and by blue galaxies in u and g.

  14. The Secret Life of Galaxies

    NASA Astrophysics Data System (ADS)

    Dressler, Alan; Abramson, Louis

    2015-04-01

    We have learned much about galaxy evolution since z = 2, and something to even higher redshifts. How can it be that we know so little about! the star formation histories (SFHs) of individual galaxies? Although great progress has been made accumulating huge samples with only rudimentary properties, progress in galaxy evolution means connecting what we've learned to detailed measurements of the life-histories of specific - not just representative - systems.

  15. Very high redshift radio galaxies

    SciTech Connect

    van Breugel, W.J.M., LLNL

    1997-12-01

    High redshift radio galaxies (HzRGs) provide unique targets for the study of the formation and evolution of massive galaxies and galaxy clusters at very high redshifts. We discuss how efficient HzRG samples ae selected, the evidence for strong morphological evolution at near-infracd wavelengths, and for jet-induced star formation in the z = 3 800 HzRG 4C41 17

  16. ATLASGAL-selected massive clumps in the inner Galaxy. III. Dust continuum characterization of an evolutionary sample

    NASA Astrophysics Data System (ADS)

    König, C.; Urquhart, J. S.; Csengeri, T.; Leurini, S.; Wyrowski, F.; Giannetti, A.; Wienen, M.; Pillai, T.; Kauffmann, J.; Menten, K. M.; Schuller, F.

    2017-03-01

    Context. Massive-star formation and the processes involved are still poorly understood. The ATLASGAL survey provides an ideal basis for detailed studies of large numbers of massive-star forming clumps covering the whole range of evolutionary stages. The ATLASGAL Top100 is a sample of clumps selected by their infrared and radio properties to be representative for the whole range of evolutionary stages. Aims: The ATLASGAL Top100 sources are the focus of a number of detailed follow-up studies that will be presented in a series of papers. In the present work we use the dust continuum emission to constrain the physical properties of this sample and identify trends as a function of source evolution. Methods: We determine flux densities from mid-infrared to submillimeter wavelength (8-870 μm) images and use these values to fit their spectral energy distributions and determine their dust temperature and flux. Combining these with recent distances from the literature including maser parallax measurements we determine clump masses, luminosities and column densities. Results: We define four distinct source classes from the available continuum data and arrange these into an evolutionary sequence. This begins with sources found to be dark at 70 μm, followed by 24 μm weak sources with an embedded 70 μm source, continues through mid-infrared bright sources and ends with infrared bright sources associated with radio emission (i.e., H ii regions). We find trends for increasing temperature, luminosity, and column density with the proposed evolution sequence, confirming that this sample is representative of different evolutionary stages of massive star formation. Our sources span temperatures from approximately 11 to 41 K, with bolometric luminosities in the range 57 L⊙-3.8 × 106L⊙. The highest masses reach 4.3 × 104M⊙ and peak column densities up to 1.1 × 1024 cm-1, and therefore have the potential to form the most massive O-type stars. We show that at least 93 sources

  17. (Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. IV. Physical properties derived from spectral energy distributions

    NASA Astrophysics Data System (ADS)

    Miettinen, O.; Delvecchio, I.; Smolčić, V.; Novak, M.; Aravena, M.; Karim, A.; Murphy, E. J.; Schinnerer, E.; Capak, P.; Ilbert, O.; Intema, H. T.; Laigle, C.; McCracken, H. J.

    2017-01-01

    Context. Submillimetre galaxies (SMGs) in the early Universe are potential antecedents of the most massive galaxies we see in the present-day Universe. An important step towards quantifying this galactic evolutionary connection is to investigate the fundamental physical properties of SMGs, such as their stellar mass content (M⋆) and star formation rate (SFR). Aims: We attempt to characterise the physical nature of a 1.1 mm selected, flux-limited, and interferometrically followed up sample of SMGs in the COSMOS field. Methods: We used the latest release of the MAGPHYS code to fit the multiwavelength (UV to radio) spectral energy distributions (SEDs) of 16 of the target SMGs, which lie at redshifts z ≃ 1.6-5.3. We also constructed the pure radio SEDs of our SMGs using three different radio bands (325 MHz, 1.4 GHz, and 3 GHz). Moreover, since two SMGs in our sample, AzTEC 1 and AzTEC 3, benefit from previous 12C16O line observations, we studied their properties in more detail. Results: The median and 16th-84th percentile ranges of M⋆, infrared (8-1000 μm) luminosity (LIR), SFR, dust temperature (Tdust), and dust mass (Mdust) were derived to be log (M⋆/M⊙) = 10.96+ 0.34-0.19, log (LIR/L⊙) = 12.93+ 0.09-0.19, SFR = 856+ 191-310M⊙ yr-1, Tdust = 40.6+ 7.5-8.1 K, and log (Mdust/M⊙) = 9.17+ 0.03-0.33, respectively. We found that 63% of our target SMGs lie above the galaxy main sequence by more than a factor of 3 and, hence, are starbursts. The 3 GHz radio sizes we have previously measured for the target SMGs were compared with the present M⋆ estimates, and we found that the z> 3 SMGs are fairly consistent with the mass-size relationship of z 2 compact, quiescent galaxies (cQGs). The median radio spectral index is found to be α = -0.77+ 0.28-0.42. The median IR-radio correlation parameter is found to be q = 2.27+ 0.27-0.13, which is lower than was measured locally (median q = 2.64). The gas-to-dust mass ratio for AzTEC 1 is derived to be δgdr = 90+ 23

  18. Radio properties of fossil galaxy groups

    NASA Astrophysics Data System (ADS)

    Miraghaei, H.; Khosroshahi, H. G.

    2016-09-01

    We study 1.4 GHz radio properties of a sample of fossil galaxy groups using GMRT radio observations and the FIRST survey catalog. Fossil galaxy groups, having no recent major mergers in their dominant galaxies and also group scale mergers, give us the opportunity to investigate the effect of galaxy merger on AGN activity. In this work, we compare the radio properties of a rich sample of fossil groups with a sample of normal galaxy groups and clusters and show that the brightest group galaxies in fossil groups are under luminous at 1.4 GHz, relative to the general population of the brightest group galaxies, indicating that the dynamically relaxed nature of fossil groups has influenced the AGN activity in their dominant galaxy.

  19. Star Formation Activity of Barred Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Kim, Eunbin; Hwang, Ho Seong; Chung, Haeun; Lee, Gwang-Ho; Park, Changbom; Cervantes Sodi, Bernardo; Kim, Sungsoo S.

    2017-08-01

    We study the star formation activity of nearby galaxies with bars using a sample of late-type galaxies at 0.02≤slant z≤slant 0.05489 and {M}r< -19.5 from the Sloan Digital Sky Survey. We compare the physical properties of strongly and weakly barred galaxies with those of non-barred galaxies that have stellar mass and redshift distributions similar to barred galaxies. We find that the star formation activity of strongly barred galaxies probed by starburstiness, g-r, {NUV}-r, and mid-infrared [3.4]-[12] colors is, on average, lower than that of non-barred galaxies. However, weakly barred galaxies do not show such a difference between barred and non-barred galaxies. The amounts of atomic and molecular gas in strongly barred galaxies are smaller than those in non-barred galaxies, and the gas metallicity is higher in strongly barred galaxies than in non-barred galaxies. The gas properties of weakly barred galaxies again show no difference from those of non-barred galaxies. We stack the optical spectra of barred and non-barred galaxies in several mass bins and fit to the stacked spectra with a spectral fitting code, STARLIGHT. We find no significant difference in stellar populations between barred and non-barred galaxies for both strongly and weakly barred galaxies. Our results are consistent with the idea that the star formation activity of barred galaxies was enhanced in the past along with significant gas consumption, and is currently lower than or similar to that of non-barred galaxies. The past star formation enhancement depends on the strength of bars.

  20. ACS Nearby Galaxy Survey

    NASA Astrophysics Data System (ADS)

    Dalcanton, Julianne

    2006-07-01

    Existing HST observations of nearby galaxies comprise a sparse and highly non-uniform archive, making comprehensive comparative studies among galaxies essentially impossible. We propose to secure HST's lasting impact on the study of nearby galaxies by undertaking a systematic, complete, and carefully crafted imaging survey of ALL galaxies in the Local Universe outside the Local Group. The resulting images will allow unprecedented measurements of: {1} the star formation history {SFH} of a >100 Mpc^3 volume of the Universe with a time resolution of Delta[log{t}]=0.25; {2} correlations between spatially resolved SFHs and environment; {3} the structure and properties of thick disks and stellar halos; and {4} the color distributions, sizes, and specific frequencies of globular and disk clusters as a function of galaxy mass and environment. To reach these goals, we will use a combination of wide-field tiling and pointed deep imaging to obtain uniform data on all 72 galaxies within a volume-limited sample extending to 3.5 Mpc, with an extension to the M81 group. For each galaxy, the wide-field imaging will cover out to 1.5 times the optical radius and will reach photometric depths of at least 2 magnitudes below the tip of the red giant branch throughout the limits of the survey volume. One additional deep pointing per galaxy will reach SNR 10 for red clump stars, sufficient to recover the ancient SFH from the color-magnitude diagram. This proposal will produce photometric information for 100 million stars {comparable to the number in the SDSS survey} and uniform multi-color images of half a square degree of sky. The resulting archive will establish the fundamental optical database for nearby galaxies, in preparation for the shift of high-resolution imaging to the near-infrared.

  1. F-VIPGI: a new adapted version of VIPGI for FORS2 spectroscopy. Application to a sample of 16 X-ray selected galaxy clusters at 0.6 ≤ z ≤ 1.2

    NASA Astrophysics Data System (ADS)

    Nastasi, A.; Scodeggio, M.; Fassbender, R.; Böhringer, H.; Pierini, D.; Verdugo, M.; Garilli, B. M.; Franzetti, P.

    2013-02-01

    Aims: The goal of this paper is twofold. Firstly, we present F-VIPGI, a new version of the VIMOS Interactive Pipeline and Graphical Interface (VIPGI) adapted to handle FORS2 spectroscopic data taken with the standard instrument configuration. Secondly, we investigate the spectro-photometric properties of a sample of galaxies residing in distant X-ray selected galaxy clusters, the optical spectra of which were reduced with this new pipeline. Methods: We provide basic technical information about the innovations of the new software and refer the reader to the original VIPGI paper for a detailed description of the core functions and performances. As a demonstration of the capabilities of the new pipeline, we then show results obtained for 16 distant (0.65 ≤ z ≤ 1.25) X-ray luminous galaxy clusters selected within the XMM-Newton Distant Cluster Project. We performed a spectral indices analysis of the extracted optical spectra of their members, based on which we created a library of composite high signal-to-noise ratio spectra. We then compared the average spectra of the passive galaxies of our sample with those computed for the same class of objects that reside in the field at similar high redshift and in groups in the local Universe. Finally, We computed the "photometric" properties of our templates and compared them with those of the Coma Cluster galaxies, which we took as representative of the local cluster population. Results: We demonstrate the capabilities of F-VIPGI, whose strength is an increased efficiency and a simultaneous shortening of FORS2 spectroscopic data reduction time by a factor of ~10 w.r.t. the standard IRAF procedures. We then discuss the quality of the final stacked optical spectra and provide them in electronic form as high-quality spectral templates, representative of passive and star-forming galaxies residing in distant galaxy clusters. By comparing the spectro-photometric properties of our templates with the local and distant galaxy

  2. An optical spectroscopic survey of the 3CR sample of radio galaxies with z < 0.3. V. Implications for the unified model for FR IIs

    NASA Astrophysics Data System (ADS)

    Baldi, Ranieri D.; Capetti, Alessandro; Buttiglione, Sara; Chiaberge, Marco; Celotti, Annalisa

    2013-12-01

    We explore the implications of our optical spectroscopic survey of 3CR radio sources with z < 0.3 for the unified model (UM) for radio-loud AGN, focusing on objects with a "edge-brightened" (FR II) radio morphology. The sample contains 33 high ionization galaxies (HIGs) and 18 broad line objects (BLOs). According to the UM, HIGs, the narrow line sources, are the nuclearly obscured counterparts of BLOs. The fraction of HIGs indicates a covering factor of the circumnuclear matter of 65% that corresponds, adopting a torus geometry, to an opening angle of 50° ± 5. No dependence on redshift and luminosity on the torus opening angle emerges. We also consider the implications for a "clumpy" torus. The distributions of total radio luminosity of HIGs and BLOs are not statistically distinguishable, as expected from the UM. Conversely, BLOs have a radio core dominance, R, more than ten times larger with respect to HIGs, as expected in case of Doppler boosting when the jets in BLOs are preferentially oriented closer to the line of sight than in HIGs. Modeling the R distributions leads to an estimate of the jet bulk Lorentz factor of Γ ~ 3-5. The test of the UM based on the radio source size is not conclusive due to the limited number of objects and because the size distribution is dominated by the intrinsic scatter rather than by projection effects. The [O II] line luminosities in HIGs and BLOs are similar but the [O III] and [O I] lines are higher in BLOs by a factor of ~2. We ascribe this effect to the presence of a line emitting region located within the walls of the obscuring torus, visible in BLOs but obscured in HIGs, with a density higher than the [O II] critical density. We find evidence that BLOs have broader [O I] and [O III] lines than HIGs of similar [O II] width, as expected in the presence of high density gas in the proximity of the central black hole. In conclusion, the radio and narrow line region (NLR) properties of HIGs and BLOs are consistent with the UM

  3. JOINT ANALYSIS OF CLUSTER OBSERVATIONS. II. CHANDRA/XMM-NEWTON X-RAY AND WEAK LENSING SCALING RELATIONS FOR A SAMPLE OF 50 RICH CLUSTERS OF GALAXIES

    SciTech Connect

    Mahdavi, Andisheh; Hoekstra, Henk; Babul, Arif; Bildfell, Chris; Jeltema, Tesla; Henry, J. Patrick

    2013-04-20

    We present a study of multiwavelength X-ray and weak lensing scaling relations for a sample of 50 clusters of galaxies. Our analysis combines Chandra and XMM-Newton data using an energy-dependent cross-calibration. After considering a number of scaling relations, we find that gas mass is the most robust estimator of weak lensing mass, yielding 15% {+-} 6% intrinsic scatter at r{sub 500}{sup WL} (the pseudo-pressure Y{sub X} yields a consistent scatter of 22% {+-} 5%). The scatter does not change when measured within a fixed physical radius of 1 Mpc. Clusters with small brightest cluster galaxy (BCG) to X-ray peak offsets constitute a very regular population whose members have the same gas mass fractions and whose even smaller (<10%) deviations from regularity can be ascribed to line of sight geometrical effects alone. Cool-core clusters, while a somewhat different population, also show the same (<10%) scatter in the gas mass-lensing mass relation. There is a good correlation and a hint of bimodality in the plane defined by BCG offset and central entropy (or central cooling time). The pseudo-pressure Y{sub X} does not discriminate between the more relaxed and less relaxed populations, making it perhaps the more even-handed mass proxy for surveys. Overall, hydrostatic masses underestimate weak lensing masses by 10% on the average at r{sub 500}{sup WL}; but cool-core clusters are consistent with no bias, while non-cool-core clusters have a large and constant 15%-20% bias between r{sub 2500}{sup WL} and r{sub 500}{sup WL}, in agreement with N-body simulations incorporating unthermalized gas. For non-cool-core clusters, the bias correlates well with BCG ellipticity. We also examine centroid shift variance and power ratios to quantify substructure; these quantities do not correlate with residuals in the scaling relations. Individual clusters have for the most part forgotten the source of their departures from self-similarity.

  4. A MULTIWAVELENGTH STUDY OF A SAMPLE OF 70 mum SELECTED GALAXIES IN THE COSMOS FIELD. I. SPECTRAL ENERGY DISTRIBUTIONS AND LUMINOSITIES

    SciTech Connect

    Kartaltepe, Jeyhan S.; Sanders, D. B.; Le Floc'h, E.; Ilbert, O.; Frayer, D. T.; Aussel, H.; Arnouts, S.; Salvato, M.; Scoville, N. Z.; Capak, P.; Surace, J.; Yan, L.; Brusa, M.; Hasinger, G.; Caputi, K.; Carollo, C. M.; Civano, F.; Elvis, M.; Faure, C.; Koekemoer, A. M. E-mail: jeyhan@noao.ed

    2010-02-01

    We present a large robust sample of 1503 reliable and unconfused 70 mum selected sources from the multiwavelength data set of the Cosmic Evolution Survey. Using the Spitzer IRAC and MIPS photometry, we estimate the total infrared (IR) luminosity, L{sub IR} (8-1000 mum), by finding the best-fit template from several different template libraries. The long-wavelength 70 and 160 mum data allow us to obtain a reliable estimate of L{sub IR}, accurate to within 0.2 and 0.05 dex, respectively. The 70 mum data point enables a significant improvement over the luminosity estimates possible with only a 24 mum detection. The full sample spans a wide range in IR luminosity, L{sub IR} approx 10{sup 8}-10{sup 14} L{sub sun}, with a median luminosity of 10{sup 11.4} L{sub sun}. We identify a total of 687 luminous, 303 ultraluminous, and 31 hyperluminous infrared galaxies (LIRGs, ULIRGs, and HyLIRGs) over the redshift range 0.01 < z < 3.5 with a median redshift of 0.5. Presented here are the full spectral energy distributions (SEDs) for each of the sources compiled from the extensive multiwavelength data set from the ultraviolet (UV) to the far-infrared. A catalog of the general properties of the sample (including the photometry, redshifts, and L{sub IR}) is included with this paper. We find that the overall shape of the SED and trends with L{sub IR} (e.g., IR color temperatures and optical-IR ratios) are similar to what has been seen in studies of local objects; however, our large sample allows us to see the extreme spread in UV to near-infrared colors spanning nearly 3 orders of magnitude. In addition, using SED fits we find possible evidence for a subset of cooler ultraluminous objects than observed locally. However, until direct observations at longer wavelengths are obtained, the peak of emission and the dust temperature cannot be well constrained. We use these SEDs, along with the deep radio and X-ray coverage of the field, to identify a large sample of candidate active

  5. The Void Galaxy Survey: Morphology and Star Formation Properties of Void Galaxies

    NASA Astrophysics Data System (ADS)

    Beygu, Burcu; Kreckel, Kathryn; van der Hulst, Thijs; Peletier, Reynier; Jarrett, Tom; van de Weygaert, Rien; van Gorkom, Jacqueline H.; Aragón-Calvo, Miguel

    2016-10-01

    We present the structural and star formation properties of 59 void galaxies as part of the Void Galaxy Survey (VGS). Our aim is to study in detail the physical properties of these void galaxies and study the effect of the void environment on galaxy properties. We use Spitzer 3.6μ and B-band imaging to study the morphology and color of the VGS galaxies. For their star formation properties, we use Hα and GALEX near-UV imaging. We compare our results to a range of galaxies of different morphologies in higher density environments. We find that the VGS galaxies are in general disk dominated and star forming galaxies. Their star formation rates are, however, often less than 1 M⊙ yr-1. There are two early-type galaxies in our sample as well. In re versus MB parameter space, VGS galaxies occupy the same space as dwarf irregulars and spirals.

  6. REGARDING THE LINE-OF-SIGHT BARYONIC ACOUSTIC FEATURE IN THE SLOAN DIGITAL SKY SURVEY AND BARYON OSCILLATION SPECTROSCOPIC SURVEY LUMINOUS RED GALAXY SAMPLES

    SciTech Connect

    Kazin, Eyal A.; Blanton, Michael R.; Scoccimarro, Roman; McBride, Cameron K.; Berlind, Andreas A.

    2010-08-20

    We analyze the line-of-sight baryonic acoustic feature in the two-point correlation function {xi} of the Sloan Digital Sky Survey luminous red galaxy (LRG) sample (0.16 < z < 0.47). By defining a narrow line-of-sight region, r{sub p} < 5.5 h {sup -1} Mpc, where r{sub p} is the transverse separation component, we measure a strong excess of clustering at {approx}110 h {sup -1} Mpc, as previously reported in the literature. We also test these results in an alternative coordinate system, by defining the line of sight as {theta} < 3{sup 0}, where {theta} is the opening angle. This clustering excess appears much stronger than the feature in the better-measured monopole. A fiducial {Lambda}CDM nonlinear model in redshift space predicts a much weaker signature. We use realistic mock catalogs to model the expected signal and noise. We find that the line-of-sight measurements can be explained well by our mocks as well as by a featureless {xi} = 0. We conclude that there is no convincing evidence that the strong clustering measurement is the line-of-sight baryonic acoustic feature. We also evaluate how detectable such a signal would be in the upcoming Baryon Oscillation Spectroscopic Survey (BOSS) LRG volume. Mock LRG catalogs (z < 0.6) suggest that (1) the narrow line-of-sight cylinder and cone defined above probably will not reveal a detectable acoustic feature in BOSS; (2) a clustering measurement as high as that in the current sample can be ruled out (or confirmed) at a high confidence level using a BOSS-sized data set; (3) an analysis with wider angular cuts, which provide better signal-to-noise ratios, can nevertheless be used to compare line-of-sight and transverse distances, and thereby constrain the expansion rate H(z) and diameter distance D{sub A}(z).

  7. The "Valencian-GALAXY-zoo"

    NASA Astrophysics Data System (ADS)

    Navarro-González, J.; Ricciardelli, E.; Quilis, V.; Vazdekis, A.

    2013-05-01

    We present a sample of the most massive galaxies (M^{*}>10^{11}{M}_{⊙}) found at z=0 in a fully cosmological simulation performed with MASCLET (Mesh Adaptative Scheme for CosmologicaL structurE evoluTion). te{quilis04} The Upper (lower) pannel shows the merger (quiet) galaxies depending on elipticity (ɛ) and velocity vs velocity-dispersion (v/σ). We use the ssp MILES models to make our galaxies bright and study some observables of our fully cosmological synthetic galaxies.

  8. A pseudo-spectrum analysis of galaxy-galaxy lensing

    NASA Astrophysics Data System (ADS)

    Hikage, Chiaki; Oguri, Masamune

    2016-10-01

    We present the application of the pseudo-spectrum method to galaxy-galaxy lensing. We derive explicit expressions for the pseudo-spectrum analysis of the galaxy-shear cross-spectrum, which is the Fourier space counterpart of the stacked galaxy-galaxy lensing profile. The pseudo-spectrum method corrects observational issues such as the survey geometry, masks of bright stars and their spikes, and inhomogeneous noise, which distort the spectrum and also mix the E-mode and the B-mode signals. Using ray-tracing simulations in N-body simulations including realistic masks, we confirm that the pseudo-spectrum method successfully recovers the input galaxy-shear cross-spectrum. We also show that the galaxy-shear cross-spectrum has an excess covariance relative to the Gaussian covariance at small scales (k ≳ 1h Mpc-1) where the shot noise is dominated in the Gaussian approximation. We find that the excess is consistent with the expectation from the halo sample variance (HSV), which originates from the matter fluctuations at scales larger than the survey area. We apply the pseudo-spectrum method to the observational data of Canada-France-Hawaii Telescope Lensing survey shear catalogue and three different spectroscopic samples of Sloan Digital Sky Survey Luminous Red Galaxy, and Baryon Oscillation Spectroscopic Survey CMASS and LOWZ galaxies. The galaxy-shear cross-spectra are significantly detected at the level of 7-10σ using the analytic covariance with the HSV contribution included. We also confirm that the observed spectra are consistent with the halo model predictions with the halo occupation distribution parameters estimated from previous work. This work demonstrates the viability of galaxy-galaxy lensing analysis in the Fourier space.

  9. IRAS observations of Seyfert galaxies

    NASA Technical Reports Server (NTRS)

    Miley, G. K.; Neugebauer, G.; Soifer, B. T.

    1985-01-01

    Infrared Astronomy Satellite measurements at 25, 60 and 100 microns were used to analyze the infrared properties of Seyfert galaxies from the Markarian and NGC Catalogs. One hundred and sixteen of 186 Seyfert galaxies were detected. About 50% of all Seyfert galaxies in the sample have 60 micron luminosities in excess of 10 to the 10th power solar luminosity, and the mean 60 micron luminosity increase with the optical B absolute magnitude. The luminosity functions of the Seyfert 1 and Seyfert 2 galaxies appear quite similar. It is possible, however, to statistically separate the two types of galaxies in color-color plots. The 100- to 60- micron energy distributions flatten systematically with increasing 60- micron luminosity. The infrared measurements provide a measure of the bolometric luminosity of the Seyfert galaxies, but do not discriminate between the physical processes involved.

  10. THE METALLICITY OF VOID DWARF GALAXIES

    SciTech Connect

    Kreckel, K.; Groves, B.; Croxall, K.; Pogge, R. W.; Van de Weygaert, R.

    2015-01-01

    The current ΛCDM cosmological model predicts that galaxy evolution proceeds more slowly in lower density environments, suggesting that voids are a prime location to search for relatively pristine galaxies that are representative of the building blocks of early massive galaxies. To test the assumption that void galaxies are more pristine, we compare the evolutionary properties of a sample of dwarf galaxies selected specifically to lie in voids with a sample of similar isolated dwarf galaxies in average density environments. We measure gas-phase oxygen abundances and gas fractions for eight dwarf galaxies (M{sub r} > –16.2), carefully selected to reside within the lowest density environments of seven voids, and apply the same calibrations to existing samples of isolated dwarf galaxies. We find no significant difference between these void dwarf galaxies and the isolated dwarf galaxies, suggesting that dwarf galaxy chemical evolution proceeds independent of the large-scale environment. While this sample is too small to draw strong conclusions, it suggests that external gas accretion is playing a limited role in the chemical evolution of these systems, and that this evolution is instead dominated mainly by the internal secular processes that are linking the simultaneous growth and enrichment of these galaxies.

  11. Astrocladistics: a phylogenetic analysis of galaxy evolution I. Character evolutions and galaxy histories

    NASA Astrophysics Data System (ADS)

    Fraix-Burnet, Didier; Choler, Philippe; Douzery, Emmanuel J. P.; Verhamme, Anne

    2006-06-01

    This series of papers is intended to present astrocladistics in some detail and evaluate this methodology in reconstructing phylogenies of galaxies. Being based on the evolution of all the characters describing galaxies, it is an objective way of understanding galaxy diversity through evolutionary relationships. In this first paper, we present the basic steps of a cladistic analysis and show both theoretically and practically that it can be applied to galaxies. For illustration, we use a sample of 50 simulated galaxies taken from the GALICS database, which are described by 91 observables (dynamics, masses and luminosities). These 50 simulated galaxies are indeed 10 different galaxies taken at 5 cosmological epochs, and they are free of merger events. The astrocladistic analysis easily reconstructs the true chronology of evolution relationships within this sample. It also demonstrates that burst characters are not relevant for galaxy evolution as a whole. A companion paper is devoted to the formalization of the concepts of formation and diversification in galaxy evolution.

  12. Giant disk galaxies : Where environment trumps mass in galaxy evolution

    NASA Astrophysics Data System (ADS)

    Courtois, Helene M.; Zaritsky, Dennis; Sorce, Jenny G.; Pomarede, Daniel

    2015-08-01

    We identify some of the most HI massive and fastest rotating disk galaxies in the local universe with the aim of probing the processes that drive the formation of these extreme disk galaxies. By combining data from the Cosmic Flows project, which has consistently reanalyzed archival galaxy HI profiles, and 3.6 micron photometry obtained with the Spitzer Space Telescope, with which we can measure stellar mass, we use the baryonic Tully-Fisher relationship to explore whether these massive galaxies are distinct.We discuss several results, but the most striking is the systematic offset of the HI-massive sample above the baryonic Tully-Fisher. These galaxies have both more gas and more stars in their disks than the typical disk galaxy of similar rotational velocity. The ``condensed" baryon fraction, fC, the fraction of the baryons in a dark matter halo that settle either as cold gas or stars into the disk, is twice as high in the HI-massive sample than typical, and almost reaches the universal baryon fraction in some cases, suggesting that the most extreme of these galaxies have little in the way of a hot baryonic component or cold baryons distributed well outside the disk. In contrast, the star formation efficiency, measured as the ratio of the mass in stars to that in both stars and gas, shows no difference between the HI-massive sample and the typical disk galaxies. We conclude that the star formation efficiency is driven by an internal, self-regulating process, while fC is affected by external factors. Neither the morphology nor the star formation rate of these galaxies is primarily determined by either their dark or stellar mass. We also found that the most massive HI detected galaxies are located preferentially in filaments. We present the first evidence of an environmental effect on galaxy evolution using a dynamical definition of a filament.

  13. Giant disc galaxies: where environment trumps mass in galaxy evolution

    NASA Astrophysics Data System (ADS)

    Courtois, H. M.; Zaritsky, D.; Sorce, J. G.; Pomarède, D.

    2015-04-01

    We identify some of the most H I-massive and fastest rotating disc galaxies in the local universe with the aim of probing the processes that drive the formation of these extreme disc galaxies. By combining data from the Cosmic Flows project, which has consistently reanalysed archival galaxy H I profiles, and 3.6 μm photometry obtained with the Spitzer Space Telescope, with which we can measure stellar mass, we use the baryonic Tully-Fisher (BTF) relationship to explore whether these massive galaxies are distinct. We discuss several results, but the most striking is the systematic offset of the H I-massive sample above the BTF. These galaxies have both more gas and more stars in their discs than the typical disc galaxy of similar rotational velocity. The `condensed' baryon fraction, fC, the fraction of the baryons in a dark matter halo that settle either as cold gas or stars into the disc, is twice as high in the H I-massive sample than typical, and almost reaches the universal baryon fraction in some cases, suggesting that the most extreme of these galaxies have little in the way of a hot baryonic component or cold baryons distributed well outside the disc. In contrast, the star formation efficiency, measured as the ratio of the mass in stars to that in both stars and gas, shows no difference between the H I-massive sample and the typical disc galaxies. We conclude that the star formation efficiency is driven by an internal, self-regulating process, while fC is affected by external factors. Neither the morphology nor the star formation rate of these galaxies is primarily determined by either their dark or stellar mass. We also found that the most massive H I detected galaxies are located preferentially in filaments. We present the first evidence of an environmental effect on galaxy evolution using a dynamical definition of a filament.

  14. Galaxies on Top of Quasars: Probing Dwarf Galaxies in the SDSS

    NASA Astrophysics Data System (ADS)

    Straka, Lorrie; York, D. G.; Noterdaeme, P.; Srianand, R.; Bowen, D. V.; Khare, P.; Bishof, M.; Whichard, Z.; Kulkarni, V. P.

    2013-07-01

    Absorption lines from galaxies at intervening redshifts in quasar spectra are sensitive probes of metals and gas that are otherwise invisible due to distance or low surface brightness. However, in order to determine the environments these absorption lines arise in, we must detect these galaxies in emission as well. Galaxies on top of quasars (GOTOQs) are low-z galaxies found intervening with background quasars in the SDSS. These galaxies have been flagged for their narrow galactic emission lines present in quasar spectra in the SDSS. Typically, the low-z nature of these galaxies allows them to be easily detected in SDSS imaging. However, a number of GOTOQs (about 10%), despite being detected in spectral emission, are NOT seen in SDSS imaging. This implies that these may be dark galaxies, dwarf galaxies, or similarly low surface brightness galaxies. Additionally, about 25% of those detected in imaging are dwarf galaxies according to their L* values. Dwarf galaxies have long been underrepresented in observations compared to theory and are known to have large extents in dark matter. Given their prevalence here in our sample we must ask what role they play in quasar absorption line systems (QSOALS). Recent detections of 21-cm galaxies with few stars imply that aborted star formation in dark matter sub halos may produce QSOALS. Thus, this sub sample of galaxies offers a unique technique for probing dark and dwarf galaxies. The sample and its properties will be discussed, including star formation rates and dust estimates, as well as prospects for the future.

  15. PEARS Emission Line Galaxies

    NASA Technical Reports Server (NTRS)

    Pirzkal, Nor; Rothberg, Barry; Ly, Chun; Rhoads, James E.; Malhotra, Sangeeta; Grogin, Norman A.; Dahlen, Tomas; Meurer, Gerhardt R.; Walsh, Jeremy; Hathi, Nimish P.; Cohen, Seth; Belini, Andrea; Holwerda, Benne W.; Straughn, Amber; Mechtley, Matthew

    2012-01-01

    We present a full analysis of the Probing Evolution And Reionization Spectroscopically (PEARS) slitless grism spectroscopic data obtained vl'ith the Advanced Camera for Surveys on HST. PEARS covers fields within both the Great Observatories Origins Deep Survey (GOODS) North and South fields, making it ideal as a random surveY of galaxies, as well as the availability of a wide variety of ancillary observations to support the spectroscopic results. Using the PEARS data we are able to identify star forming galaxies within the redshift volume 0 < z < 1.5. Star forming regions in the PEARS survey are pinpointed independently of the host galaxy. This method allOW8 us to detect the presence of multiple emission line regions (ELRs) within a single galaxy. 1162 [OII], [OIII] and/or H-alpha emission lines have been identified in the PEARS sample of approx 906 galaxies down to a limiting flux of approx 10 - 18 erg/s/sq cm . The ELRs have also been compared to the properties of the host galaxy, including morphology, luminosity, and mass. From this analysis we find three key results: 1) The computed line luminosities show evidence of a flattening in the luminosity function with increasing redshift; 2) The star forming systems show evidence of disturbed morphologies, with star formation occurring predominantly within one effective (half-light) radius. However, the morphologies show no correlation with host stellar mass; and 3) The number density of star forming galaxies with M(*) >= 10(exp 9) Solar M decreases by an order of magnitude at z<=0.5 relative to the number at 0.5 < z < 0.9 in support of the argument for galaxy downsizing.

  16. SUPERLUMINOUS SPIRAL GALAXIES

    SciTech Connect

    Ogle, Patrick M.; Lanz, Lauranne; Nader, Cyril; Helou, George

    2016-02-01

    We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster galaxies, with r-band monochromatic luminosity L{sub r} = 8–14L* (4.3–7.5 × 10{sup 44} erg s{sup −1}). These super spiral galaxies are also giant and massive, with diameter D = 57–134 kpc and stellar mass M{sub stars} = 0.3–3.4 × 10{sup 11}M{sub ⊙}. We find 53 super spirals out of a complete sample of 1616 SDSS galaxies with redshift z < 0.3 and L{sub r} > 8L*. The closest example is found at z = 0.089. We use existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS and Wide-field Infrared Survey Explorer colors are consistent with normal star-forming spirals on the blue sequence. However, the extreme masses and rapid SFRs of 5–65 M{sub ⊙} yr{sup −1} place super spirals in a sparsely populated region of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a diverse range of environments, from isolation to cluster centers. We find four super spiral galaxy systems that are late-stage major mergers—a possible clue to their formation. We suggest that super spirals are a remnant population of unquenched, massive disk galaxies. They may eventually become massive lenticular galaxies after they are cut off from their gas supply and their disks fade.

  17. HYDROSTATIC GAS CONSTRAINTS ON SUPERMASSIVE BLACK HOLE MASSES: IMPLICATIONS FOR HYDROSTATIC EQUILIBRIUM AND DYNAMICAL MODELING IN A SAMPLE OF EARLY-TYPE GALAXIES

    SciTech Connect

    Humphrey, Philip J.; Buote, David A.; Brighenti, Fabrizio; Gebhardt, Karl; Mathews, William G.

    2009-10-01

    We present new mass measurements for the supermassive black holes (SMBHs) in the centers of three early-type galaxies. The gas pressure in the surrounding, hot interstellar medium (ISM) is measured through spatially resolved spectroscopy with the Chandra X-ray Observatory, allowing the SMBH mass (M {sub BH}) to be inferred directly under the hydrostatic approximation. This technique does not require calibration against other SMBH measurement methods and its accuracy depends only on the ISM being close to hydrostatic, which is supported by the smooth X-ray isophotes of the galaxies. Combined with results from our recent study of the elliptical galaxy NGC 4649, this brings the number of galaxies with SMBHs measured in this way to four. Of these, three already have mass determinations from the kinematics of either the stars or a central gas disk, and hence join only a handful of galaxies with M {sub BH} measured by more than one technique. We find good agreement between the different methods, providing support for the assumptions implicit in both the hydrostatic and the dynamical models. The stellar mass-to-light ratios for each galaxy inferred by our technique are in agreement with the predictions of stellar population synthesis models assuming a Kroupa initial mass function (IMF). This concurrence implies that no more than {approx}10%-20% of the ISM pressure is nonthermal, unless there is a conspiracy between the shape of the IMF and nonthermal pressure. Finally, we compute Bondi accretion rates (M-dot{sub bondi}), finding that the two galaxies with the highest M-dot{sub bondi} exhibit little evidence of X-ray cavities, suggesting that the correlation with the active galactic nuclei jet power takes time to be established.

  18. Mass calibration and cosmological analysis of the SPT-SZ galaxy cluster sample using velocity dispersion σ v and x-ray Y X measurements

    DOE PAGES

    Bocquet, S.; Saro, A.; Mohr, J. J.; ...

    2015-01-30

    Here, we present a velocity-dispersion-based mass calibration of the South Pole Telescope Sunyaev-Zel'dovich effect survey (SPT-SZ) galaxy cluster sample. Using a homogeneously selected sample of 100 cluster candidates from 720 deg2 of the survey along with 63 velocity dispersion (σv) and 16 X-ray YX measurements of sample clusters, we simultaneously calibrate the mass-observable relation and constrain cosmological parameters. Our method accounts for cluster selection, cosmological sensitivity, and uncertainties in the mass calibrators. The calibrations using σv and YX are consistent at the 0.6σ level, with the σ v calibration preferring ~16% higher masses. We use the full SPTCL data setmore » (SZ clusters+σv+YX) to measure σ8(Ωm/0.27)0.3 = 0.809 ± 0.036 within a flat ΛCDM model. The SPT cluster abundance is lower than preferred by either the WMAP9 or Planck+WMAP9 polarization (WP) data, but assuming that the sum of the neutrino masses is mν = 0.06 eV, we find the data sets to be consistent at the 1.0σ level for WMAP9 and 1.5σ for Planck+WP. Allowing for larger Σmν further reconciles the results. When we combine the SPTCL and Planck+WP data sets with information from baryon acoustic oscillations and Type Ia supernovae, the preferred cluster masses are 1.9σ higher than the YX calibration and 0.8σ higher than the σ v calibration. Given the scale of these shifts (~44% and ~23% in mass, respectively), we execute a goodness-of-fit test; it reveals no tension, indicating that the best-fit model provides an adequate description of the data. Using the multi-probe data set, we measure Ωm = 0.299 ± 0.009 and σ8 = 0.829 ± 0.011. Within a νCDM model we find Σmν = 0.148 ± 0.081 eV. We present a consistency test of the cosmic growth rate using SPT clusters. Allowing both the growth index γ and the dark energy equation-of-state parameter w to vary, we find γ = 0.73 ± 0.28 and w = –1.007 ± 0.065, demonstrating that the eΣxpansion and the growth

  19. Mass Calibration and Cosmological Analysis of the SPT-SZ Galaxy Cluster Sample Using Velocity Dispersion σ v and X-Ray Y X Measurements

    NASA Astrophysics Data System (ADS)

    Bocquet, S.; Saro, A.; Mohr, J. J.; Aird, K. A.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Bazin, G.; Benson, B. A.; Bleem, L. E.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Chiu, I.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; Desai, S.; de Haan, T.; Dietrich, J. P.; Dobbs, M. A.; Foley, R. J.; Forman, W. R.; Gangkofner, D.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Hennig, C.; Hlavacek-Larrondo, J.; Holder, G. P.; Holzapfel, W. L.; Hrubes, J. D.; Jones, C.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Meyer, S. S.; Mocanu, L.; Murray, S. S.; Padin, S.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruel, J.; Ruhl, J. E.; Saliwanchik, B. R.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Spieler, H. G.; Stalder, B.; Stanford, S. A.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, C. W.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.

    2015-02-01

    We present a velocity-dispersion-based mass calibration of the South Pole Telescope Sunyaev-Zel'dovich effect survey (SPT-SZ) galaxy cluster sample. Using a homogeneously selected sample of 100 cluster candidates from 720 deg2 of the survey along with 63 velocity dispersion (σ v ) and 16 X-ray Y X measurements of sample clusters, we simultaneously calibrate the mass-observable relation and constrain cosmological parameters. Our method accounts for cluster selection, cosmological sensitivity, and uncertainties in the mass calibrators. The calibrations using σ v and Y X are consistent at the 0.6σ level, with the σ v calibration preferring ~16% higher masses. We use the full SPTCL data set (SZ clusters+σ v +Y X) to measure σ8(Ωm/0.27)0.3 = 0.809 ± 0.036 within a flat ΛCDM model. The SPT cluster abundance is lower than preferred by either the WMAP9 or Planck+WMAP9 polarization (WP) data, but assuming that the sum of the neutrino masses is ∑m ν = 0.06 eV, we find the data sets to be consistent at the 1.0σ level for WMAP9 and 1.5σ for Planck+WP. Allowing for larger ∑m ν further reconciles the results. When we combine the SPTCL and Planck+WP data sets with information from baryon acoustic oscillations and Type Ia supernovae, the preferred cluster masses are 1.9σ higher than the Y X calibration and 0.8σ higher than the σ v calibration. Given the scale of these shifts (~44% and ~23% in mass, respectively), we execute a goodness-of-fit test; it reveals no tension, indicating that the best-fit model provides an adequate description of the data. Using the multi-probe data set, we measure Ωm = 0.299 ± 0.009 and σ8 = 0.829 ± 0.011. Within a νCDM model we find ∑m ν = 0.148 ± 0.081 eV. We present a consistency test of the cosmic growth rate using SPT clusters. Allowing both the growth index γ and the dark energy equation-of-state parameter w to vary, we find γ = 0.73 ± 0.28 and w = -1.007 ± 0.065, demonstrating that the expansion and the growth

  20. The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Cosmological implications of the Fourier space wedges of the final sample

    NASA Astrophysics Data System (ADS)

    Grieb, Jan Niklas; Sánchez, Ariel G.; Salazar-Albornoz, Salvador; Scoccimarro, Román; Crocce, Martín; Dalla Vecchia, Claudio; Montesano, Francesco; Gil-Marín, Héctor; Ross, Ashley J.; Beutler, Florian; Rodríguez-Torres, Sergio; Chuang, Chia-Hsun; Prada, Francisco; Kitaura, Francisco-Shu; Cuesta, Antonio J.; Eisenstein, Daniel J.; Percival, Will J.; Vargas-Magaña, Mariana; Tinker, Jeremy L.; Tojeiro, Rita; Brownstein, Joel R.; Maraston, Claudia; Nichol, Robert C.; Olmstead, Matthew D.; Samushia, Lado; Seo, Hee-Jong; Streblyanska, Alina; Zhao, Gong-bo

    2017-01-01

    We extract cosmological information from the anisotropic power spectrum measurements from the recently completed Baryon Oscillation Spectroscopic Survey (BOSS), extending the concept of clustering wedges to Fourier space. Making use of new FFT-based estimators, we measure the power spectrum clustering wedges of the BOSS sample by filtering out the information of Legendre multipoles ℓ > 4. Our modelling of these measurements is based on novel approaches to describe non-linear evolution, bias, and redshift-space distortions, which we test using synthetic catalogues based on large-volume N-body simulations. We are able to include smaller scales than in previous analyses, resulting in tighter cosmological constraints. Using three overlapping redshift bins, we measure the angular diameter distance, the Hubble parameter, and the cosmic growth rate, and explore the cosmological implications of our full shape clustering measurements in combination with CMB and SN Ia data. Assuming a ΛCDM cosmology, we constrain the matter density to Ω M= 0.311_{-0.010}^{+0.009} and the Hubble parameter to H_0 = 67.6_{-0.6}^{+0.7} km s^{-1} Mpc^{-1}, at a confidence level (CL) of 68 per cent. We also allow for non-standard dark energy models and modifications of the growth rate, finding good agreement with the ΛCDM paradigm. For example, we constrain the equation-of-state parameter to w = -1.019_{-0.039}^{+0.048}. This paper is part of a set that analyses the final galaxy clustering dataset from BOSS. The measurements and likelihoods presented here are combined with others in Alam et al. (2016) to produce the final cosmological constraints from BOSS.

  1. The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Cosmological implications of the Fourier space wedges of the final sample

    NASA Astrophysics Data System (ADS)

    Grieb, Jan Niklas; Sánchez, Ariel G.; Salazar-Albornoz, Salvador; Scoccimarro, Román; Crocce, Martín; Dalla Vecchia, Claudio; Montesano, Francesco; Gil-Marín, Héctor; Ross, Ashley J.; Beutler, Florian; Rodríguez-Torres, Sergio; Chuang, Chia-Hsun; Prada, Francisco; Kitaura, Francisco-Shu; Cuesta, Antonio J.; Eisenstein, Daniel J.; Percival, Will J.; Vargas-Magaña, Mariana; Tinker, Jeremy L.; Tojeiro, Rita; Brownstein, Joel R.; Maraston, Claudia; Nichol, Robert C.; Olmstead, Matthew D.; Samushia, Lado; Seo, Hee-Jong; Streblyanska, Alina; Zhao, Gong-bo

    2017-05-01

    We extract cosmological information from the anisotropic power-spectrum measurements from the recently completed Baryon Oscillation Spectroscopic Survey (BOSS), extending the concept of clustering wedges to Fourier space. Making use of new fast-Fourier-transform-based estimators, we measure the power-spectrum clustering wedges of the BOSS sample by filtering out the information of Legendre multipoles ℓ > 4. Our modelling of these measurements is based on novel approaches to describe non-linear evolution, bias and redshift-space distortions, which we test using synthetic catalogues based on large-volume N-body simulations. We are able to include smaller scales than in previous analyses, resulting in tighter cosmological constraints. Using three overlapping redshift bins, we measure the angular-diameter distance, the Hubble parameter and the cosmic growth rate, and explore the cosmological implications of our full-shape clustering measurements in combination with cosmic microwave background and Type Ia supernova data. Assuming a Λ cold dark matter (ΛCDM) cosmology, we constrain the matter density to Ω M= 0.311_{-0.010}^{+0.009} and the Hubble parameter to H_0 = 67.6_{-0.6}^{+0.7} km s^{-1 Mpc^{-1}}, at a confidence level of 68 per cent. We also allow for non-standard dark energy models and modifications of the growth rate, finding good agreement with the ΛCDM paradigm. For example, we constrain the equation-of-state parameter to w = -1.019_{-0.039}^{+0.048}. This paper is part of a set that analyses the final galaxy-clustering data set from BOSS. The measurements and likelihoods presented here are combined with others in Alam et al. to produce the final cosmological constraints from BOSS.

  2. (Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. I. Multiwavelength identifications and redshift distribution

    NASA Astrophysics Data System (ADS)

    Miettinen, O.; Smolčić, V.; Novak, M.; Aravena, M.; Karim, A.; Masters, D.; Riechers, D. A.; Bussmann, R. S.; McCracken, H. J.; Ilbert, O.; Bertoldi, F.; Capak, P.; Feruglio, C.; Halliday, C.; Kartaltepe, J. S.; Navarrete, F.; Salvato, M.; Sanders, D.; Schinnerer, E.; Sheth, K.

    2015-05-01

    We used the Plateau de Bure Interferometer (PdBI) to map a sample of 15 submillimetre galaxies (SMGs) in the COSMOS field at the wavelength of 1.3 mm. The target SMGs were originally discovered in the James Clerk Maxwell Telescope (JCMT)/AzTEC 1.1 mm continuum survey at S/N1.1 mm = 4-4.5. This paper presents, for the first time, interferometric millimetre-wavelength observations of these sources. The angular resolution of our observations, 1''&dotbelow;8, allowed us to accurately determine the positions of the target SMGs. Using a detection threshold of S/N1.3 mm> 4.5 regardless of multiwavelength counterpart association, and 4 sample. To study the overall multiplicity and redshift distribution of flux-limited samples of SMGs we combined these sources with the 15 brightest JCMT/AzTEC SMGs detected at 1.1 mm, AzTEC1-15, and studied previously. This constitutes a complete, flux- and S/N-limited 1.1-mm selected sample. We find that the median redshift for the 15 brightest JCMT/AzTEC SMGs (tilde{z}= 3.05 ± 0.44) is consistent with that for AzTEC16-30. This conforms to recent observational findings that SMGs do not exhibit any significant trend between the redshift and (sub)mm flux density. For the combined AzTEC1-30 sample we derive a median redshift of tilde{z}= 3.17 ± 0.27, consistent with previous results based on mm

  3. An Exploration of Dusty Galaxies

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-04-01

    Submillimeter galaxies i.e., galaxies that we detect in the submillimeter wavelength range are mysterious creatures. Its only within the last couple decades that weve had telescope technology capable of observing them, and were only now getting to the point where angular resolution limits allow us to examine them closely. A new study has taken advantage of new capabilities to explore the properties of a sample of 52 of thesegalaxies.Dusty Star FormationSubmillimeter galaxies are generally observed in the early universe. Though theyre faint in other wavebands, theyre extremely luminous in infrared and submillimeter their infrared luminosities are typically trillions of times the Suns luminosity. This is thought to be because these galaxies are very actively forming stars at rates of hundreds of times that of the Milky Way!Example 10 10 true-color images of ten submillimeter galaxies in the authors ALMA-identified sample. [Simpson et al. 2017]Submillimeter galaxies are also extremely dusty, so we dont see their star formation directly in optical wavelengths. Instead, we see the stellar light after its been absorbed and reemitted by interstellar dust lanes were indirectly observing heavily obscured star formation.Why look for submillimeter galaxies? Studying them can help us to learn about galaxy and star formation early in our universes history, and help us to understand how the universe has evolved into what we see locally today.Submillimeter StrugglesDue to angular resolution limitations in the past, we often couldnt pin down the exact locations of submillimeter galaxies, preventing us from examining them properly. But now a team of scientists has used the Atacama Large Millimeter/submillimeter array (ALMA) to precisely locate 52 submillimeter galaxies identified by the Submillimeter Common-User Bolometer Array (SCUBA-2) in the UKIDSS Ultra Deep Survey field.The precise locations made possible by ALMA allowed the team led by James Simpson (University of Edinburgh

  4. FIR statistics of paired galaxies

    NASA Technical Reports Server (NTRS)

    Sulentic, Jack W.

    1990-01-01

    Much progress has been made in understanding the effects of interaction on galaxies (see reviews in this volume by Heckman and Kennicutt). Evidence for enhanced emission from galaxies in pairs first emerged in the radio (Sulentic 1976) and optical (Larson and Tinsley 1978) domains. Results in the far infrared (FIR) lagged behind until the advent of the Infrared Astronomy Satellite (IRAS). The last five years have seen numerous FIR studies of optical and IR selected samples of interacting galaxies (e.g., Cutri and McAlary 1985; Joseph and Wright 1985; Kennicutt et al. 1987; Haynes and Herter 1988). Despite all of this work, there are still contradictory ideas about the level and, even, the reality of an FIR enhancement in interacting galaxies. Much of the confusion originates in differences between the galaxy samples that were studied (i.e., optical morphology and redshift coverage). Here, the authors report on a study of the FIR detection properties for a large sample of interacting galaxies and a matching control sample. They focus on the distance independent detection fraction (DF) statistics of the sample. The results prove useful in interpreting the previously published work. A clarification of the phenomenology provides valuable clues about the physics of the FIR enhancement in galaxies.

  5. Deficiency of "Thin" Stellar Bars in Seyfert Host Galaxies.

    PubMed

    Shlosman; Peletier; Knapen

    2000-06-01

    Using all available major samples of Seyfert galaxies and their corresponding closely matched control samples of nonactive galaxies, we find that the bar ellipticities (or axial ratios) in Seyfert galaxies are systematically different from those in nonactive galaxies. Overall, there is a deficiency of bars with large ellipticities (i.e., "thin" or "strong" bars) in Seyfert galaxies compared to nonactive galaxies. Accompanied with a large dispersion due to small number statistics, this effect is strictly speaking at the 2 sigma level. To obtain this result, the active galaxy samples of near-infrared surface photometry were matched to those of normal galaxies in type, host galaxy ellipticity, absolute magnitude, and, to some extent, redshift. We discuss possible theoretical explanations of this phenomenon within the framework of galactic evolution, and, in particular, of radial gas redistribution in barred galaxies. Our conclusions provide further evidence that Seyfert hosts differ systematically from their nonactive counterparts on scales of a few kiloparsecs.

  6. Spectroscopic Observations of Merging Galaxies

    NASA Astrophysics Data System (ADS)

    Donzelli, C. J.; Pastoriza, M. G.

    2000-07-01

    In this paper we describe the spectroscopic and infrared properties of a sample of 25 merging galaxy pairs, selected from the catalog of Arp & Madore, and we compare them with those observed in a similar sample of interacting galaxies (Donzelli & Pastoriza). It is noted that mergers as well as interacting systems comprise a wide range of spectral types, going from those corresponding to well-evolved stellar populations (older than 200 Myr) to those that show clear signatures of H II regions with stellar populations younger than 8 Myr. However, merger galaxies show on average more excited spectra than interacting pairs, which could be attributed to lower gas metallicity. From the emission lines we also found that merging systems show on average higher (about a factor of 2) star formation rates than interacting galaxies. Classical diagnostic diagrams show that only three of 50 of the galaxies (6%) present some form of nuclear activity: two Seyfert galaxies and one LINER. However, through a detailed analysis of the pure emission-line spectra, we conclude that this fraction may raise up to 23% of the mergers if we consider that some galaxies host a low-luminosity active nucleus surrounded by strong star-forming regions. This latter assumption is also supported by the infrared colors of the galaxies. Regarding to the total infrared luminosities, the merging galaxies show on average an IR luminosity, log(Lir)=10.7, lower than that of interacting systems, log(Lir)=10.9. We find that only three mergers of the sample (12%) can be classified as luminous infrared galaxies, while this fraction increases to 24% in the interacting sample. Based on observations made at CASLEO. Complejo Astronómico El Leoncito is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan.

  7. The VIMOS VLT Deep Survey final data release: a spectroscopic sample of 35 016 galaxies and AGN out to z ~ 6.7 selected with 17.5 ≤ iAB ≤ 24.75

    NASA Astrophysics Data System (ADS)

    Le Fèvre, O.; Cassata, P.; Cucciati, O.; Garilli, B.; Ilbert, O.; Le Brun, V.; Maccagni, D.; Moreau, C.; Scodeggio, M.; Tresse, L.; Zamorani, G.; Adami, C.; Arnouts, S.; Bardelli, S.; Bolzonella, M.; Bondi, M.; Bongiorno, A.; Bottini, D.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; de la Torre, S.; Foucaud, S.; Franzetti, P.; Gavignaud, I.; Guzzo, L.; Iovino, A.; Lemaux, B.; López-Sanjuan, C.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mazure, A.; Mellier, Y.; Merighi, R.; Merluzzi, P.; Paltani, S.; Pellò, R.; Pollo, A.; Pozzetti, L.; Scaramella, R.; Tasca, L.; Vergani, D.; Vettolani, G.; Zanichelli, A.; Zucca, E.

    2013-11-01

    Context. Deep representative surveys of galaxies at different epochs are needed to make progress in understanding galaxy evolution. Aims: We describe the completed VIMOS VLT Deep Survey and the final data release of 35 016 galaxies and type-I AGN with measured spectroscopic redshifts covering all epochs up to redshift z ~ 6.7, in areas from 0.142 to 8.7 square degrees, and volumes from 0.5 × 106 to 2 × 107 h-3 Mpc3. Methods: We selected samples of galaxies based solely on their i-band magnitude reaching iAB = 24.75. Spectra were obtained with VIMOS on the ESO-VLT integrating 0.75 h, 4.5 h, and 18 h for the Wide, Deep, and Ultra-Deep nested surveys, respectively. We demonstrate that any "redshift desert" can be crossed successfully using spectra covering 3650 ≤ λ ≤ 9350 Å. A total of 1263 galaxies were again observed independently within the VVDS and from the VIPERS and MASSIV surveys. They were used to establish the redshift measurements reliability, to assess completeness in the VVDS sample, and to provide a weighting scheme taking the survey selection function into account. We describe the main properties of the VVDS samples, and the VVDS is compared to other spectroscopic surveys in the literature. Results: In total we have obtained spectroscopic redshifts for 34 594 galaxies, 422 type-I AGN, and 12 430 Galactic stars. The survey enabled identifying galaxies up to very high redshifts with 4669 redshifts in 1 ≤ zspec ≤ 2, 561 in 2 ≤ zspec ≤ 3, and 468 with zspec > 3, and specific populations like Lyman-α emitters were identified out to z = 6.62. We show that the VVDS occupies a unique place in the parameter space defined by area, depth, redshift coverage, and number of spectra. Conclusions: The VIMOS VLT Deep Survey provides a comprehensive survey of the distant universe, covering all epochs since z ~ 6, or more than 12 Gyr of cosmic time, with a uniform selection, which is the largest such sample to date. A wealth of science results derived from

  8. A Multiwavelength Study of a Sample of 70 μm Selected Galaxies in the COSMOS Field. I. Spectral Energy Distributions and Luminosities

    NASA Astrophysics Data System (ADS)

    Kartaltepe, Jeyhan S.; Sanders, D. B.; Le Floc'h, E.; Frayer, D. T.; Aussel, H.; Arnouts, S.; Ilbert, O.; Salvato, M.; Scoville, N. Z.; Surace, J.; Yan, L.; Brusa, M.; Capak, P.; Caputi, K.; Carollo, C. M.; Civano, F.; Elvis, M.; Faure, C.; Hasinger, G.; Koekemoer, A. M.; Lee, N.; Lilly, S.; Liu, C. T.; McCracken, H. J.; Schinnerer, E.; Smolčić, V.; Taniguchi, Y.; Thompson, D. J.; Trump, J.

    2010-02-01

    We present a large robust sample of 1503 reliable and unconfused 70 μm selected sources from the multiwavelength data set of the Cosmic Evolution Survey. Using the Spitzer IRAC and MIPS photometry, we estimate the total infrared (IR) luminosity, L IR (8-1000 μm), by finding the best-fit template from several different template libraries. The long-wavelength 70 and 160 μm data allow us to obtain a reliable estimate of L IR, accurate to within 0.2 and 0.05 dex, respectively. The 70 μm data point enables a significant improvement over the luminosity estimates possible with only a 24 μm detection. The full sample spans a wide range in IR luminosity, L IR ≈ 108-1014 L sun, with a median luminosity of 1011.4 L sun. We identify a total of 687 luminous, 303 ultraluminous, and 31 hyperluminous infrared galaxies (LIRGs, ULIRGs, and HyLIRGs) over the redshift range 0.01 < z < 3.5 with a median redshift of 0.5. Presented here are the full spectral energy distributions (SEDs) for each of the sources compiled from the extensive multiwavelength data set from the ultraviolet (UV) to the far-infrared. A catalog of the general properties of the sample (including the photometry, redshifts, and L IR) is included with this paper. We find that the overall shape of the SED and trends with L IR (e.g., IR color temperatures and optical-IR ratios) are similar to what has been seen in studies of local objects; however, our large sample allows us to see the extreme spread in UV to near-infrared colors spanning nearly 3 orders of magnitude. In addition, using SED fits we find possible evidence for a subset of cooler ultraluminous objects than observed locally. However, until direct observations at longer wavelengths are obtained, the peak of emission and the dust temperature cannot be well constrained. We use these SEDs, along with the deep radio and X-ray coverage of the field, to identify a large sample of candidate active galactic nuclei (AGNs). We find that the fraction of AGNs

  9. Interpreting the Properties of Galaxies

    NASA Astrophysics Data System (ADS)

    Conti, Alberto

    Galaxies exhibit a wide range of physical properties (e.g., luminosities, colors, velocity widths, star formation, gas and stellar content) and the evolutionary processes responsible for these properties are numerous and complex. Understanding which processes shape the observable properties of galaxies and which others play only a minor role, inherently requires a large sample of galaxies. Moreover, if we want to understand why galaxies have the properties they do, we need a theory of galaxy formation. The standard paradigm of galaxy formation assumes that most of the matter is dark and dissipationless and that, under the influence of gravity, structures on galactic and larger scales grow hierarchically (from Gaussian initial conditions) with smaller objects forming first. Gas, moving under the gravitational influence of the dark component, dissipates and collapses at the center of the potential wells provided by the dark matter. In this picture the internal structure of the dark matter clumps and their formation history regulate the global properties of galaxies. However, these properties must also depend on how gas cools to form the dense clouds that seed star formation and how star formation affects the surrounding medium with the injection of energy and heavy elements. I show how simple, ``semi-analytic'' parameterizations are used to describe the highly non-linear aforementioned processes and to predict a wide range of properties of the galaxy population for any specific cosmogony. I then present a simple and flexible framework to extract from the numerous observable properties of disk galaxies that semi-analytic models predict, only those that are needed to characterize the sample as a whole. This framework makes use of the well-know statistical technique of Principal Component Analysis (PCA). Moreover, I correlate the semi-analytic assumptions with the PCA findings and determine which, among our theoretical assumptions, shape the observable galaxies

  10. Les galaxies

    NASA Astrophysics Data System (ADS)

    Combes, Francoise

    2016-08-01

    Considerable progress has been made on galaxy formation and evolution in recent years, and new issues. The old Hubble classification according to the tuning fork of spirals, lenticulars and ellipticals, is still useful but has given place to the red sequence, the blue cloud and the green valley, showing a real bimodality of types between star forming galaxies (blue) and quenched ones (red). Large surveys have shown that stellar mass and environment density are the two main factors of the evolution from blue to red sequences. Evolution is followed directly with redshift through a look-back time of more than 12 billion years. The most distant galaxy at z=11. has already a stellar mass of a billion suns. In an apparent anti-hierarchical scenario, the most massive galaxies form stars early on, while essentially dwarf galaxies are actively star-formers now. This downsizing feature also applies to the growth of super-massive black holes at the heart of each bulgy galaxy. The feedback from active nuclei is essential to explain the distribution of mass in galaxies, and in particular to explain why the fraction of baryonic matter is so low, lower by more than a factor 5 than the baryonic fraction of the Universe. New instruments just entering in operation, like MUSE and ALMA, provide a new and rich data flow, which is developed in this series of articles.

  11. Asymmetric Galaxies: Nature or Nurture?

    NASA Astrophysics Data System (ADS)

    Wilcots, E. M.

    2010-10-01

    Asymmetry is a common characteristic of many disk galaxies, but we have little understanding of its causes. In this contribution we look at the H I properties of a sample of Magellanic spirals, some of the most lopsided galaxies in the local Universe, and a sample of isolated spirals. In neither case do we see evidence of a link between the presence of a companion and asymmetry; indeed, asymmetry persists even in the absence of a companion or evidence of a recent interaction. These results suggest that once it arises, asymmetry may be a very long-lived characteristic of disk galaxies.

  12. The ESO UVES Advanced Data Products quasar sample - V. Identifying the galaxy counterpart to the sub-damped Lyα system towards Q 2239-2949

    NASA Astrophysics Data System (ADS)

    Zafar, Tayyaba; Møller, Palle; Péroux, Céline; Quiret, Samuel; Fynbo, Johan P. U.; Ledoux, Cédric; Deharveng, Jean-Michel

    2017-02-01

    Gas flows in and out of galaxies are one of the key unknowns in today's galaxy evolution studies. Because gas flows carry mass, energy, and metals, they are believed to be closely connected to the star formation history of galaxies. Most of these processes take place in the circum-galactic medium (CGM) which remains challenging to observe in emission. A powerful tool to study the CGM gas is offered by combining observations of the gas traced by absorption lines in quasar spectra with detection of the stellar component of the same absorbing-galaxy. To this end, we have targeted the zabs = 1.825 sub-damped Lyα absorber (sub-DLA) towards the zem = 2.102 quasar 2dF J 223941.8-294955 (hereafter Q 2239-2949) with the ESO VLT/X-Shooter spectrograph. Our aim is to investigate the relation between its properties in emission and in absorption. The derived metallicity of the sub-DLA with log N(H I) = 19.84 ± 0.14 cm-2 is [M/H] > -0.75. Using the Voigt profile optical depth method, we measure Δv90(Fe II) = 64 km s-1. The sub-DLA galaxy counterpart is located at an impact parameter of 2{^''.}4 ± 0{^''.}2 (20.8 ± 1.7 kpc at z = 1.825). We have detected Lyα and marginal [O II] emissions. The mean measured flux of the Lyα line is FLy α ∼ 5.7 × 10-18 erg s-1 cm-2 Å-1, corresponding to a dust uncorrected SFR of ∼0.13 M⊙ yr-1.

  13. Star formation in Kiso measle galaxies

    NASA Astrophysics Data System (ADS)

    Elmegreen, Debra M.; Elmegreen, B. G.

    2012-05-01

    The Kiso sample of several thousand local ultraviolet-bright galaxies includes galaxies classified as irregular disk galaxies with large star-forming complexes (I,g). We selected a sample of all I,g galaxies with both Sloan Digital Sky Survey images and spectra. They contain up to several dozen giant clumps each, so we refer to them as measle galaxies. We determined ages and masses of the clumps based on a comparison of photometry with population synthesis models of cluster evolution. The spectra were used to determine global star formation rates. Several hundred clumps were measured in the sample, with masses ranging from 10^5 to several x10^8 solar masses, scaling with galaxy absolute g magnitude of -14 to -21 mag. The galaxies are starbursting, sitting above the Groth strip “main sequence” of star formation rate versus galaxy mass by an order of magnitude. These Kiso measle galaxies have 10x the star formation rates of the Kiso tadpole galaxies. We compare their clump luminosity distribution functions with normal disk galaxies.

  14. Microvariability in Seyfert galaxies

    USGS Publications Warehouse

    Carini, M.T.; Noble, J.C.; Miller, H.R.

    2003-01-01

    We present the results of a search for microvariability in a sample of eight Seyfert galaxies. Microvariability (i.e., variations occurring on timescales of tens of minutes to hours) has been conclusively demonstrated to exist in the class of active galactic nuclei (AGNs) known as blazars. Its existence in other classes of AGNs is far less certain. We present the results of a study of eight Seyfert 1 galaxies, which were intensively monitored in order to determine whether such variations exist in these objects. Only one object, Ark 120, displayed any evidence of microvariations. The implications of these results with respect to current models of the mechanisms responsible for the observed emission in Seyfert galaxies are discussed. We compare our results with those obtained from other studies of microvariability in different classes of AGNs.

  15. Interacting Galaxies

    NASA Image and Video Library

    2008-04-24

    This beautiful pair of interacting galaxies consists of NGC 5754, the large spiral on the right, and NGC 5752, the smaller companion in the bottom left corner of the image. This image is from NASA Hubble Space Telescope.

  16. Galaxy and mass assembly (GAMA): projected galaxy clustering

    NASA Astrophysics Data System (ADS)

    Farrow, D. J.; Cole, Shaun; Norberg, Peder; Metcalfe, N.; Baldry, I.; Bland-Hawthorn, Joss; Brown, Michael J. I.; Hopkins, A. M.; Lacey, Cedric G.; Liske, J.; Loveday, Jon; Palamara, David P.; Robotham, A. S. G.; Sridhar, Srivatsan

    2015-12-01

    We measure the projected two-point correlation function of galaxies in the 180 deg2 equatorial regions of the GAMA II survey, for four different redshift slices between z = 0.0 and 0.5. To do this, we further develop the Cole method of producing suitable random catalogues for the calculation of correlation functions. We find that more r-band luminous, more massive and redder galaxies are more clustered. We also find that red galaxies have stronger clustering on scales less than ˜3 h-1 Mpc. We compare to two different versions of the GALFORM galaxy formation model, Lacey et al. (in preparation) and Gonzalez-Perez et al., and find that the models reproduce the trend of stronger clustering for more massive galaxies. However, the models underpredict the clustering of blue galaxies, can incorrectly predict the correlation function on small scales and underpredict the clustering in our sample of galaxies with {˜ } 3 Lr^*. We suggest possible avenues to explore to improve these clustering predictions. The measurements presented in this paper can be used to test other galaxy formation models, and we make the measurements available online to facilitate this.

  17. FRACTAL DIMENSION OF GALAXY ISOPHOTES

    SciTech Connect

    Thanki, Sandip; Rhee, George; Lepp, Stephen E-mail: grhee@physics.unlv.edu

    2009-09-15

    In this paper we investigate the use of the fractal dimension of galaxy isophotes in galaxy classification. We have applied two different methods for determining fractal dimensions to the isophotes of elliptical and spiral galaxies derived from CCD images. We conclude that fractal dimension alone is not a reliable tool but that combined with other parameters in a neural net algorithm the fractal dimension could be of use. In particular, we have used three parameters to segregate the ellipticals and lenticulars from the spiral galaxies in our sample. These three parameters are the correlation fractal dimension D {sub corr}, the difference between the correlation fractal dimension and the capacity fractal dimension D {sub corr} - D {sub cap}, and, thirdly, the B - V color of the galaxy.

  18. Andromeda Galaxy

    NASA Astrophysics Data System (ADS)

    Walterbos, R.; Murdin, P.

    2000-11-01

    The Andromeda galaxy is the closest SPIRAL GALAXY to the MILKY WAY, just visible to the naked eye on a dark night as a faint smudge of light in the constellation Andromeda. The earliest records of the Andromeda nebula, as it is still often referred to, date back to AD 964, to the `Book of the Fixed Stars' published by the Persian astronomer AL-SÛFI. The first European to officially note the Andro...

  19. MASS CALIBRATION AND COSMOLOGICAL ANALYSIS OF THE SPT-SZ GALAXY CLUSTER SAMPLE USING VELOCITY DISPERSION σ {sub v} AND X-RAY Y {sub X} MEASUREMENTS

    SciTech Connect

    Bocquet, S.; Saro, A.; Mohr, J. J.; Bazin, G.; Chiu, I.; Desai, S.; Aird, K. A.; Ashby, M. L. N.; Bayliss, M.; Bautz, M.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T.; Brodwin, M.; Cho, H. M.; Clocchiatti, A.; De Haan, T.; and others

    2015-02-01

    We present a velocity-dispersion-based mass calibration of the South Pole Telescope Sunyaev-Zel'dovich effect survey (SPT-SZ) galaxy cluster sample. Using a homogeneously selected sample of 100 cluster candidates from 720 deg{sup 2} of the survey along with 63 velocity dispersion (σ {sub v}) and 16 X-ray Y {sub X} measurements of sample clusters, we simultaneously calibrate the mass-observable relation and constrain cosmological parameters. Our method accounts for cluster selection, cosmological sensitivity, and uncertainties in the mass calibrators. The calibrations using σ {sub v} and Y {sub X} are consistent at the 0.6σ level, with the σ {sub v} calibration preferring ∼16% higher masses. We use the full SPT{sub CL} data set (SZ clusters+σ {sub v}+Y {sub X}) to measure σ{sub 8}(Ω{sub m}/0.27){sup 0.3} = 0.809 ± 0.036 within a flat ΛCDM model. The SPT cluster abundance is lower than preferred by either the WMAP9 or Planck+WMAP9 polarization (WP) data, but assuming that the sum of the neutrino masses is ∑m {sub ν} = 0.06 eV, we find the data sets to be consistent at the 1.0σ level for WMAP9 and 1.5σ for Planck+WP. Allowing for larger ∑m {sub ν} further reconciles the results. When we combine the SPT{sub CL} and Planck+WP data sets with information from baryon acoustic oscillations and Type Ia supernovae, the preferred cluster masses are 1.9σ higher than the Y {sub X} calibration and 0.8σ higher than the σ {sub v} calibration. Given the scale of these shifts (∼44% and ∼23% in mass, respectively), we execute a goodness-of-fit test; it reveals no tension, indicating that the best-fit model provides an adequate description of the data. Using the multi-probe data set, we measure Ω{sub m} = 0.299 ± 0.009 and σ{sub 8} = 0.829 ± 0.011. Within a νCDM model we find ∑m {sub ν} = 0.148 ± 0.081 eV. We present a consistency test of the cosmic growth rate using SPT clusters. Allowing both the growth index γ and the dark energy equation

  20. Investigating the Processes Driving Low-Mass Galaxy Evolution with Gas Metallicities of Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Ly, Chun; Malkan, Matthew; Nagao, Tohru; Hayashi, Masao; Kashikawa, Nobunari; Shimasaku, Kazuhiro; Motohara, Kentaro

    2013-02-01

    There appears to be a ``fundamental" relationship that links the stellar masses, star-formation rates (SFRs), and gas metallicities of local galaxies. It has been used to constrain the major processes in galaxy evolution. However, it is unclear whether (1) this observed relation holds at earlier cosmic time, and (2) if it applies to low-mass galaxies and/or those with relatively higher specific SFRs (sSFRs). We request follow-up Hectospec spectroscopy %and DEIMOS spectroscopy to obtain gas metallicity measurements in key unexplored domains of galaxy parameter space. We will target Ntarget low-mass high equivalent width (EW) emission-line galaxies at zrange in the Subaru Deep Field (SDF). This sample is a factor of almost 4 larger than the existing data for galaxies with similar redshifts, SFRs and stellar masses. The SDF is ideal for such a survey because of its unique multi-wavelength imaging data that allow us to (1) identify a much higher surface density of high-EW star-forming galaxies over a wide redshift range than in any other survey, and (2) determine stellar masses and SFRs for individual galaxies. With the largest spectroscopic sample of low mass and/or high sSFR galaxies, we will determine the relationships between metallicity, stellar mass, and SFRs for dwarf galaxies. We will examine if the same galaxy evolution processes in massive galaxies also hold for lower mass galaxies over the past six billion years.

  1. AGN Host Galaxy Properties And Mass Function

    NASA Astrophysics Data System (ADS)

    Bongiorno, Angela

    2016-10-01

    Supermassive black hole growth, nuclear activity, and galaxy evolution have been found to be closely related. In the context of AGN-galaxy coevolution, I will discuss about the relation found between the host galaxy properties and the central BH and I will present the latest determination of the host galaxy stellar mass function (HGMF), and the specific accretion rate distribution function (SARDF), derived from the XMM-COSMOS sample up to z˜2.5, with particular focus on AGN feedback as possible responsible mechanism for galaxy quenching.

  2. Chemical Classification of Nearby Active Galaxies

    NASA Astrophysics Data System (ADS)

    Aladro, R.; Martín, S.; Kramer, C.

    2015-12-01

    We present an unbiased λ=3 mm survey done with the IRAM 30 telescope towards the central parts of eight galaxies considered as archetypes of nearby starbursts, galaxies with an active galactic nucleus (AGN) and ultra-luminous infrared galaxies (ULIRGs). The spatial resolution range from ˜200 pc to ˜1.6 kpc, depending on the galaxy. We compare the abundances of thirty-seven species among the sample, and highlight the molecules that characterise the gas in each of them. These results can be very useful to prepare future interferometric observations of active galaxies.

  3. Frankenstein Galaxy

    NASA Image and Video Library

    2016-07-11

    The galaxy UGC 1382 has been revealed to be far larger and stranger than previously thought. Astronomers relied on a combination of ground-based and space telescopes to uncover the true nature of this "Frankenstein galaxy." The composite image shows the same galaxy as viewed with different instruments. The component images are also available. In the image at left, UGC 1382 appears to be a simple elliptical galaxy, based on optical data from the Sloan Digital Sky Survey (SDSS). But spiral arms emerged when astronomers incorporated ultraviolet data from the Galaxy Evolution Explorer (GALEX) and deep optical data from SDSS, as seen in the middle image. Combining that with a view of low-density hydrogen gas (shown in green), detected at radio wavelengths by the Very Large Array, scientists discovered that UGC 1382 is a giant, and one of the largest isolated galaxies known. GALEX in particular was able detect very faint features because it operated from space, which is necessary for UV observations because ultraviolet light is absorbed by the Earth's atmosphere. Astronomers also used Stripe 82 of SDSS, a small region of sky where SDSS imaged the sky 80 times longer than the original standard SDSS survey. This enabled optical detection of much fainter features as well. http://photojournal.jpl.nasa.gov/catalog/PIA20695

  4. Morphological Peculiarities of Distant and Local Galaxies

    NASA Astrophysics Data System (ADS)

    Wu, K. L.; Faber, S. M.; Lauer, T. R.

    1997-12-01

    Detailed images from the Hubble Space Telescope (HST) have sparked a surge of interest in morphological peculiarities in both distant and local galaxies. Several groups have developed criteria by which to classify peculiarities in galaxy morphology (e.g., Abraham et al. 1996, Naim et al. 1997). In order to study peculiar galaxies at high redshifts, it is crucial to have a solid understanding of both the morphological peculiarities in local galaxies and the appearance of local galaxies if they were observed at higher redshifts. We are developing several algorithms to quantify the types and degree of peculiarity seen in galaxy morphology. These algorithms, or peculiarity indices, are sensitive to several different types of features. The indices are applied initially to two samples: (1) a local galaxy sample, comprised of a subset of the Frei, et al. 1996 ``Catalog of Nearby Galaxies,'' along with several merger candidates from Hibbard & van Gorkom 1996 and from a run on the Lick Observatory Nickel 40-inch telescope by one of the authors (KLW); and (2) a sample of simulated z ~ 0.8 galaxies. The images of the local galaxies are resampled, and noise is added, to reflect the sampling and noise levels found in the Hubble Deep Field (HDF). The galaxy sizes and surface brightnesses are cosmologically shifted to simulate observations of these galaxies through the HST F814W ( ~ I) filter at z ~ 0.8. This study expands upon previous work by providing a realistic view of which local morphological features we can expect to measure robustly when observed at high redshifts with the current observational technology. We also demonstrate the effectiveness of our peculiarity indices in differentiating between ``normal'' (i.e., Hubble Sequence type) galaxies and ``peculiar'' galaxies at these two epochs.

  5. Bayesian anatomy of galaxy structure

    NASA Astrophysics Data System (ADS)

    Yoon, Ilsang

    In this thesis I develop Bayesian approach to model galaxy surface brightness and apply it to a bulge-disc decomposition analysis of galaxies in near-infrared band, from Two Micron All Sky Survey (2MASS). The thesis has three main parts. First part is a technical development of Bayesian galaxy image decomposition package GALPHAT based on Markov chain Monte Carlo algorithm. I implement a fast and accurate galaxy model image generation algorithm to reduce computation time and make Bayesian approach feasible for real science analysis using large ensemble of galaxies. I perform a benchmark test of G ALPHAT and demonstrate significant improvement in parameter estimation with a correct statistical confidence. Second part is a performance test for full Bayesian application to galaxy bulge-disc decomposition analysis including not only the parameter estimation but also the model comparison to classify different galaxy population. The test demonstrates that GALPHAT has enough statistical power to make a reliable model inference using galaxy photometric survey data. Bayesian prior update is also tested for parameter estimation and Bayes factor model comparison and it shows that informative prior significantly improves the model inference in every aspects. Last part is a Bayesian bulge-disc decomposition analysis using 2MASS Ks-band selected samples. I characterise the luminosity distributions in spheroids, bulges and discs separately in the local Universe and study the galaxy morphology correlation, by full utilizing the ensemble parameter posterior of the entire galaxy samples. It shows that to avoid a biased inference, the parameter covariance and model degeneracy has to be carefully characterized by the full probability distribution.

  6. GALEX NUV Lyman break galaxies

    NASA Astrophysics Data System (ADS)

    Williger, G. M.; Haberzettl, L.; Lehnert, M. D.; Nesvadba, N. P. H.; Valls-Gabaud, D.

    2010-12-01

    Lyman Break Galaxies (LBGs) have been the benchmarks against which other samples of high redshift galaxies have been compared for the last 2 decades. They are unique in that no other selection mechanism allows us to study galaxies selected in a consistent manner over redshifts 0.5≲ z≲ 7. An important remaining gap is the redshift range z˜1.5-2.5, which includes NUV-band dropouts. We searched for LBGs at this epoch using very sensitive multi-wavelength data from the FUV to mid-IR in the GOODS-S. We combined the dropout technique with color selection to identify star-forming galaxies at 1.5≲ z≲ 2.5. We find only a small overlap with the BM/BX selection method (Adelberger et al. 2004), and our sample of ˜ 200 z˜ 2 LBG candidates includes a significant number of relatively redder LBGs. By comparing our results to other selection methods for star-forming galaxies at z˜2 (BM/BX, BzK), we can show that the use of true dropout selection results in a cleaner, more efficient sample of LBG candidates. Our selected z˜ 2 LBG candidates are more consistent with LBG samples at z≤ 3 than BM/BX and BzK galaxies, despite our sample including relatively younger, lower mass systems.

  7. Galaxy Selection and the Surface Brightness Distribution

    NASA Astrophysics Data System (ADS)

    McGaugh, Stacy S.; Bothun, Gregory D.; Schombert, James M.

    1995-08-01

    Optical surveys for galaxies are biased against the inclusion of low surface brightness (LSB) galaxies. Disney [Nature, 263,573(1976)] suggested that the constancy of disk central surface brightness noticed by Freeman [ApJ, 160,811(1970)] was not a physical result, but instead was an artifact of sample selection. Since LSB galaxies do exist, the pertinent and still controversial issue is if these newly discovered galaxies constitute a significant percentage of the general galaxy population. In this paper, we address this issue by determining the space density of galaxies as a function of disk central surface brightness. Using the physically reasonable assumption (which is motivated by the data) that central surface brightness is independent of disk scale length, we arrive at a distribution which is roughly flat (i.e., approximately equal numbers of galaxies at each surface brightness) faintwards of the Freeman (1970) value. Brightwards of this, we find a sharp decline in the distribution which is analogous to the turn down in the luminosity function at L^*^. An intrinsically sharply peaked "Freeman law" distribution can be completely ruled out, and no Gaussian distribution can fit the data. Low surface brightness galaxies (those with central surface brightness fainter than 22 B mag arcsec^-2^) comprise >~ 1/2 the general galaxy population, so a representative sample of galaxies at z = 0 does not really exist at present since past surveys have been insensitive to this component of the general galaxy population.

  8. Global dust attenuation in disc galaxies: strong variation with specific star formation and stellar mass, and the importance of sample selection

    NASA Astrophysics Data System (ADS)

    Devour, Brian M.; Bell, Eric F.

    2016-06-01

    We study the relative dust attenuation-inclination relation in 78 721 nearby galaxies using the axis ratio dependence of optical-near-IR colour, as measured by the Sloan Digital Sky Survey, the Two Micron All Sky Survey, and the Wide-field Infrared Survey Explorer. In order to avoid to the greatest extent possible attenuation-driven biases, we carefully select galaxies using dust attenuation-independent near- and mid-IR luminosities and colours. Relative u-band attenuation between face-on and edge-on disc galaxies along the star-forming main sequence varies from ˜0.55 mag up to ˜1.55 mag. The strength of the relative attenuation varies strongly with both specific star formation rate and galaxy luminosity (or stellar mass). The dependence of relative attenuation on luminosity is not monotonic, but rather peaks at M3.4 μm ≈ -21.5, corresponding to M* ≈ 3 × 1010 M⊙. This behaviour stands seemingly in contrast to some older studies; we show that older works failed to reliably probe to higher luminosities, and were insensitive to the decrease in attenuation with increasing luminosity for the brightest star-forming discs. Back-of-the-envelope scaling relations predict the strong variation of dust optical depth with specific star formation rate and stellar mass. More in-depth comparisons using the scaling relations to model the relative attenuation require the inclusion of star-dust geometry to reproduce the details of these variations (especially at high luminosities), highlighting the importance of these geometrical effects.

  9. The dwarfs beyond: The stellar-to-halo mass relation for a new sample of intermediate redshift low-mass galaxies

    SciTech Connect

    Miller, Sarah H.; Ellis, Richard S.; Newman, Andrew B.; Benson, Andrew

    2014-02-20

    A number of recent challenges to the standard ΛCDM paradigm relate to discrepancies that arise in comparing the abundance and kinematics of local dwarf galaxies with the predictions of numerical simulations. Such arguments rely heavily on the assumption that the Local Volume's dwarf and satellite galaxies form a representative distribution in terms of their stellar-to-halo mass ratios. To address this question, we present new, deep spectroscopy using DEIMOS on Keck for 82 low-mass (10{sup 7}-10{sup 9} M {sub ☉}), star-forming galaxies at intermediate redshift (0.2 < z < 1). For 50% of these we are able to determine resolved rotation curves using nebular emission lines and thereby construct the stellar mass Tully-Fisher relation to masses as low as 10{sup 7} M {sub ☉}. Using scaling relations determined from weak lensing data, we convert this to a stellar-to-halo mass relation for comparison with abundance matching predictions. We find a discrepancy between our observations and the predictions from abundance matching in the sense that we observe 3-12 times more stellar mass at a given halo mass. We suggest possible reasons for this discrepancy, as well as improved tests for the future.

  10. Disrupted Stars in Unusual Galaxies

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-03-01

    Tidal disruption events (TDEs) occur when a star passes a little too close to a supermassive black hole at the center of a galaxy. Tidal forces from the black hole cause the passing star to be torn apart, resulting in a brief flare of radiation as the stars material accretes onto the black hole. A recent study asks the following question: do TDEs occur most frequently in an unusual type of galaxy?A Trend in DisruptionsSo far, we have data from eight candidate TDEs that peaked in optical and ultraviolet wavelengths. The spectra from these observations have shown an intriguing trend: many of these TDEs host galaxies exhibit weak line emission (indicating little or no current star-formation activity), and yet they show strong Balmer absorption lines (indicating star formation activity occurred within the last Gyr). These quiescent, Balmer-strong galaxies likely underwent a period of intense star formation that recently ended.To determine if TDEs are overrepresented in such galaxies, a team of scientists led by Decker French (Steward Observatory, University of Arizona) has quantified the fraction of galaxies in the Sloan Digital Sky Survey (SDSS) that exhibit similar properties to those of TDE hosts.Quantifying OverrepresentationSpectral characteristics of SDSS galaxies (gray) and TDE candidate host galaxies (colored points): line emission vs. Balmer absorption. The lower right-hand box identifies thequiescent, Balmer-strong galaxies which contain most TDE events, yet are uncommon among the galaxy sample as a whole. Click for a better look! [French et al. 2016]French and collaborators compare the optical spectra of the TDE host galaxies to those of nearly 600,000 SDSS galaxies, using two different cutoffs for the Balmer absorption the indicator of past star formation. Their strictest cut, filtering for very high Balmer absorption, selected only 0.2% of the SDSS galaxies, yet 38% of the TDEs are hosted in such galaxies. Using a more relaxed cutoff selects 2.3% of

  11. Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Miller, Christopher J. Miller

    2012-03-01

    There are many examples of clustering in astronomy. Stars in our own galaxy are often seen as being gravitationally bound into tight globular or open clusters. The Solar System's Trojan asteroids cluster at the gravitational Langrangian in front of Jupiter’s orbit. On the largest of scales, we find gravitationally bound clusters of galaxies, the Virgo cluster (in the constellation of Virgo at a distance of ˜50 million light years) being a prime nearby example. The Virgo cluster subtends an angle of nearly 8◦ on the sky and is known to contain over a thousand member galaxies. Galaxy clusters play an important role in our understanding of theUniverse. Clusters exist at peaks in the three-dimensional large-scale matter density field. Their sky (2D) locations are easy to detect in astronomical imaging data and their mean galaxy redshifts (redshift is related to the third spatial dimension: distance) are often better (spectroscopically) and cheaper (photometrically) when compared with the entire galaxy population in large sky surveys. Photometric redshift (z) [Photometric techniques use the broad band filter magnitudes of a galaxy to estimate the redshift. Spectroscopic techniques use the galaxy spectra and emission/absorption line features to measure the redshift] determinations of galaxies within clusters are accurate to better than delta_z = 0.05 [7] and when studied as a cluster population, the central galaxies form a line in color-magnitude space (called the the E/S0 ridgeline and visible in Figure 16.3) that contains galaxies with similar stellar populations [15]. The shape of this E/S0 ridgeline enables astronomers to measure the cluster redshift to within delta_z = 0.01 [23]. The most accurate cluster redshift determinations come from spectroscopy of the member galaxies, where only a fraction of the members need to be spectroscopically observed [25,42] to get an accurate redshift to the whole system. If light traces mass in the Universe, then the locations

  12. IRAC Imaging of LSB Galaxies

    NASA Astrophysics Data System (ADS)

    Schombert, James; McGaugh, Stacy; Lelli, Federico

    2017-04-01

    We propose a program to observe a large sample of Low Surface Brightness (LSB) galaxies. Large galaxy surveys conducted with Spitzer suffer from the unavoidable selection bias against LSB systems (e.g., the S4G survey). Even those programs thathave specifically targeted LSB galaxies have usually been restricted objects of intermediate surface brightness (between 22 and 23 B mag/ []). Our sample is selected to be of a more extreme LSB nature (with central surface brightness fainter than 23 Bmag/[]). Even warm, Spitzer is the ideal instrument to image these low contrast targets in the near infrared: our sample goes a considerable way towards remedying this hole in the Spitzer legacy archive, also increasing coverage in terms of stellar mass, gas mass, and SFR. The sample will be used to address the newly discovered radial acceleration relation (RAR) in disk galaxies. While issues involving the connection between baryons and dark matter have been known since the development of the global baryonic Tully-Fisher (bTF) relation, it is only in the last six months that the particle physics and theoretical communities have recognized and responded to the local coupling between dark and baryonic matter represented by the RAR. This important new correlation is effectively a new natural law for galaxies. Spitzer photometry has been at the forefront of resolving the stellar mass component in galaxies that make-up the RAR and is the primary reason for the discovery of this new kinematic law.

  13. Analysis of Sunyaev-Zel'dovich effect mass-observable relations using South Pole Telescope observations of an X-ray selected sample of low-mass galaxy clusters and groups

    NASA Astrophysics Data System (ADS)

    Liu, J.; Mohr, J.; Saro, A.; Aird, K. A.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Benson, B. A.; Bleem, L. E.; Bocquet, S.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Chiu, I.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dietrich, J. P.; Dobbs, M. A.; Foley, R. J.; Gangkofner, D.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Hennig, C.; Hlavacek-Larrondo, J.; Holder, G. P.; Holzapfel, W. L.; Hrubes, J. D.; Jones, C.; Keisler, R.; Lee, A. T.; Leitch, E. M.; Lueker, M.; Luong-Van, D.; McDonald, M.; McMahon, J. J.; Meyer, S. S.; Mocanu, L.; Murray, S. S.; Padin, S.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruel, J.; Ruhl, J. E.; Saliwanchik, B. R.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Spieler, H. G.; Stalder, B.; Staniszewski, Z.; Stark, A. A.; Story, K.; Šuhada, R.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.

    2015-04-01

    We use microwave observations from the South Pole Telescope (SPT) to examine the Sunyaev-Zel'dovich effect (SZE) signatures of a sample of 46 X-ray selected groups and clusters drawn from ˜6 deg2 of the XMM-Newton Blanco Cosmology Survey. These systems extend to redshift z = 1.02 and probe the SZE signal to the lowest X-ray luminosities (≥1042 erg s-1) yet; these sample characteristics make this analysis complementary to previous studies. We develop an analysis tool, using X-ray luminosity as a mass proxy, to extract selection-bias-corrected constraints on the SZE significance and Y500 mass relations. The former is in good agreement with an extrapolation of the relation obtained from high-mass clusters. However, the latter, at low masses, while in good agreement with the extrapolation from the high-mass SPT clusters, is in tension at 2.8σ with the Planck constraints, indicating the low-mass systems exhibit lower SZE signatures in the SPT data. We also present an analysis of potential sources of contamination. For the radio galaxy point source population, we find 18 of our systems have 843 MHz Sydney University Molonglo Sky Survey sources within 2 arcmin of the X-ray centre, and three of these are also detected at significance >4 by SPT. Of these three, two are associated with the group brightest cluster galaxies, and the third is likely an unassociated quasar candidate. We examine the impact of these point sources on our SZE scaling relation analyses and find no evidence of biases. We also examine the impact of dusty galaxies using constraints from the 220 GHz data. The stacked sample provides 2.8σ significant evidence of dusty galaxy flux, which would correspond to an average underestimate of the SPT Y500 signal that is (17 ± 9) per cent in this sample of low-mass systems. Finally, we explore the impact of future data from SPTpol and XMM-XXL, showing that it will lead to a factor of 4 to 5 tighter constraints on these SZE mass-observable relations.

  14. Analysis of Sunyaev-Zel'dovich effect mass-observable relations using South Pole Telescope observations of an X-ray selected sample of low-mass galaxy clusters and groups

    SciTech Connect

    Liu, J.; Mohr, J.; Saro, A.; Aird, K. A.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Benson, B. A.; Bleem, L. E.; Bocquet, S.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Chiu, I.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dietrich, J. P.; Dobbs, M. A.; Foley, R. J.; Gangkofner, D.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Hennig, C.; Hlavacek-Larrondo, J.; Holder, G. P.; Holzapfel, W. L.; Hrubes, J. D.; Jones, C.; Keisler, R.; Lee, A. T.; Leitch, E. M.; Lueker, M.; Luong-Van, D.; McDonald, M.; McMahon, J. J.; Meyer, S. S.; Mocanu, L.; Murray, S. S.; Padin, S.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruel, J.; Ruhl, J. E.; Saliwanchik, B. R.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Spieler, H. G.; Stalder, B.; Staniszewski, Z.; Stark, A. A.; Story, K.;  uhada, R.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.

    2015-02-25

    We use microwave observations from the South Pole Telescope (SPT) to examine the Sunyaev–Zel'dovich effect (SZE) signatures of a sample of 46 X-ray selected groups and clusters drawn from ~6 deg2 of the XMM–Newton Blanco Cosmology Survey. These systems extend to redshift z = 1.02 and probe the SZE signal to the lowest X-ray luminosities (≥1042 erg s-1) yet; these sample characteristics make this analysis complementary to previous studies. We develop an analysis tool, using X-ray luminosity as a mass proxy, to extract selection-bias-corrected constraints on the SZE significance and Y_500 mass relations. The former is in good agreement with an extrapolation of the relation obtained from high-mass clusters. However, the latter, at low masses, while in good agreement with the extrapolation from the high-mass SPT clusters, is in tension at 2.8σ with the Planck constraints, indicating the low-mass systems exhibit lower SZE signatures in the SPT data. We also present an analysis of potential sources of contamination. For the radio galaxy point source population, we find 18 of our systems have 843 MHz Sydney University Molonglo Sky Survey sources within 2 arcmin of the X-ray centre, and three of these are also detected at significance >4 by SPT. Of these three, two are associated with the group brightest cluster galaxies, and the third is likely an unassociated quasar candidate. We examine the impact of these point sources on our SZE scaling relation analyses and find no evidence of biases. We also examine the impact of dusty galaxies using constraints from the 220 GHz data. The stacked sample provides 2.8σ significant evidence of dusty galaxy flux, which would correspond to an average underestimate of the SPT Y_500 signal that is (17 ± 9)per cent in this sample of low-mass systems. Finally, we explore the impact of future data from SPTpol and XMM-XXL, showing that it will lead to a factor of 4 to 5 tighter constraints on

  15. Analysis of Sunyaev-Zel'dovich effect mass-observable relations using South Pole Telescope observations of an X-ray selected sample of low-mass galaxy clusters and groups

    SciTech Connect

    Liu, J.; Mohr, J. J.; Saro, A.; Aird, K. A.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Benson, B. A.; Bleem, L. E.; Bocquet, S.; Carlstrom, J. E.; Chang, C. L.

    2015-04-11

    We use microwave observations from the South Pole Telescope (SPT) to examine the Sunyaev-Zel'dovich effect (SZE) signatures of a sample of 46 X-ray selected groups and clusters drawn from similar to 6 deg(2) of the XMM-Newton Blanco Cosmology Survey. These systems extend to redshift z = 1.02 and probe the SZE signal to the lowest X-ray luminosities (>= 10(42) erg s(-1)) yet; these sample characteristics make this analysis complementary to previous studies. We develop an analysis tool, using X-ray luminosity as a mass proxy, to extract selection-bias-corrected constraints on the SZE significance and Y-500 mass relations. The former is in good agreement with an extrapolation of the relation obtained from high-mass clusters. However, the latter, at low masses, while in good agreement with the extrapolation from the high-mass SPT clusters, is in tension at 2.8 sigma with the Planck constraints, indicating the low-mass systems exhibit lower SZE signatures in the SPT data. We also present an analysis of potential sources of contamination. For the radio galaxy point source population, we find 18 of our systems have 843 MHz Sydney University Molonglo Sky Survey sources within 2 arcmin of the X-ray centre, and three of these are also detected at significance >4 by SPT. Of these three, two are associated with the group brightest cluster galaxies, and the third is likely an unassociated quasar candidate. We examine the impact of these point sources on our SZE scaling relation analyses and find no evidence of biases. We also examine the impact of dusty galaxies using constraints from the 220 GHz data. The stacked sample provides 2.8 sigma significant evidence of dusty galaxy flux, which would correspond to an average underestimate of the SPT Y-500 signal that is (17 +/- 9) per cent in this sample of low-mass systems. Finally, we explore the impact of future data from SPTpol and XMM-XXL, showing that it will lead to a factor of 4 to 5 tighter constraints on these SZE mass

  16. The IRAS galaxy 0421+040P06: An active spiral (?) galaxy with extended radio lobes

    NASA Technical Reports Server (NTRS)

    Beichman, C. A.; Wynn-Williams, C. G.; Lonsdale, C. J.; Persson, S. E.; Heasley, J. N.; Miley, G. K.; Soifer, B. T.; Neugebauer, G.; Becklin, E. E.; Houck, J. R.

    1984-01-01

    The infrared bright galaxy 0421+040P06 detected by IRAS at 25 and 60 microns was studied at optical, infrared, and radio wavelength. It is a luminous galaxy with apparent spiral structure emitting 4 x 10 to the 37th power from far-infrared to optical wavelengths. Optical spectroscopy reveals a Seyfert 2 emission line spectrum, making 0421+040P06 the first active galaxy selected from an unbiased infrared survey of galaxies. The fact that this galaxy shows a flatter energy distribution with more 25 micron emission than other galaxies in the infrared sample may be related to the presence of an intense active nucleus. The radio observations reveal the presence of a non-thermal source that, at 6 cm, shows a prominent double lobed structure 20 to 30 kpc in size extending beyond the optical confines of the galaxy. The radio source is three to ten times larger than structures previously seen in spiral galaxies.

  17. ENVIRONMENTAL DEPENDENCE OF OTHER GALAXY PROPERTIES FOR HIGH STELLAR MASS AND LOW STELLAR MASS GALAXIES

    SciTech Connect

    Deng Xinfa; Wen Xiaoqing; Xu Jianying; Ding Yingping; Huang Tong

    2010-06-10

    At a stellar mass of 3 x 10{sup 10} M {sub {Theta}} we divide the volume-limited Main galaxy sample of the Sloan Digital Sky Survey Data Release 6 (SDSS DR6) into two distinct families and explore the environmental dependence of galaxy properties for High Stellar Mass (HSM) and Low Stellar Mass (LSM) galaxies. It is found that for HSM and LSM galaxies, the environmental dependence of some typical galaxy properties, such as color, morphologies, and star formation activities, is still very strong, which at least shows that the stellar mass is not fundamental in correlations between galaxy properties and the environment. We also note that the environmental dependence of the size for HSM and LSM galaxies is fairly weak, which is mainly due to the galaxy size being insensitive to environment.

  18. Galaxy Zoo: quantitative visual morphological classifications for 48 000 galaxies from CANDELS

    NASA Astrophysics Data System (ADS)

    Simmons, B. D.; Lintott, Chris; Willett, Kyle W.; Masters, Karen L.; Kartaltepe, Jeyhan S.; Häußler, Boris; Kaviraj, Sugata; Krawczyk, Coleman; Kruk, S. J.; McIntosh, Daniel H.; Smethurst, R. J.; Nichol, Robert C.; Scarlata, Claudia; Schawinski, Kevin; Conselice, Christopher J.; Almaini, Omar; Ferguson, Henry C.; Fortson, Lucy; Hartley, William; Kocevski, Dale; Koekemoer, Anton M.; Mortlock, Alice; Newman, Jeffrey A.; Bamford, Steven P.; Grogin, N. A.; Lucas, Ray A.; Hathi, Nimish P.; McGrath, Elizabeth; Peth, Michael; Pforr, Janine; Rizer, Zachary; Wuyts, Stijn; Barro, Guillermo; Bell, Eric F.; Castellano, Marco; Dahlen, Tomas; Dekel, Avishai; Ownsworth, Jamie; Faber, Sandra M.; Finkelstein, Steven L.; Fontana, Adriano; Galametz, Audrey; Grützbauch, Ruth; Koo, David; Lotz, Jennifer; Mobasher, Bahram; Mozena, Mark; Salvato, Mara; Wiklind, Tommy

    2017-02-01

    We present quantified visual morphologies of approximately 48 000 galaxies observed in three Hubble Space Telescope legacy fields by the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) and classified by participants in the Galaxy Zoo project. 90 per cent of galaxies have z ≤ 3 and are observed in rest-frame optical wavelengths by CANDELS. Each galaxy received an average of 40 independent classifications, which we combine into detailed morphological information on galaxy features such as clumpiness, bar instabilities, spiral structure, and merger and tidal signatures. We apply a consensus-based classifier weighting method that preserves classifier independence while effectively down-weighting significantly outlying classifications. After analysing the effect of varying image depth on reported classifications, we also provide depth-corrected classifications which both preserve the information in the deepest observations and also enable the use of classifications at comparable depths across the full survey. Comparing the Galaxy Zoo classifications to previous classifications of the same galaxies shows very good agreement; for some applications, the high number of independent classifications provided by Galaxy Zoo provides an advantage in selecting galaxies with a particular morphological profile, while in others the combination of Galaxy Zoo with other classifications is a more promising approach than using any one method alone. We combine the Galaxy Zoo classifications of `smooth' galaxies with parametric morphologies to select a sample of featureless discs at 1 ≤ z ≤ 3, which may represent a dynamically warmer progenitor population to the settled disc galaxies seen at later epochs.

  19. Small-scale galaxy clustering in the eagle simulation

    NASA Astrophysics Data System (ADS)

    Artale, M. Celeste; Pedrosa, Susana E.; Trayford, James W.; Theuns, Tom; Farrow, Daniel J.; Norberg, Peder; Zehavi, Idit; Bower, Richard G.; Schaller, Matthieu

    2017-09-01

    We study present-day galaxy clustering in the eagle cosmological hydrodynamical simulation. eagle's galaxy formation parameters were calibrated to reproduce the redshift z = 0.1 galaxy stellar mass function, and the simulation also reproduces galaxy colours well. The simulation volume is too small to correctly sample large-scale fluctuations and we therefore concentrate on scales smaller than a few mega parsecs. We find very good agreement with observed clustering measurements from the Galaxy And Mass Assembly (GAMA) survey, when galaxies are binned by stellar mass, colour or luminosity. However, low-mass red galaxies are clustered too strongly, which is at least partly due to limited numerical resolution. Apart from this limitation, we conclude that eagle galaxies inhabit similar dark matter haloes as observed GAMA galaxies, and that the radial distribution of satellite galaxies, as a function of stellar mass and colour, is similar to that observed as well.

  20. The Shape of Galaxy Structures

    NASA Astrophysics Data System (ADS)

    Panko, Elena; Juszczyk, Teresa; Biernacka, Monika; Flin, Piotr

    2009-08-01

    An analysis is presented for a statistically complete sample of 547 galaxy structures with z <= 0.16, each containing at least 10 objects. The sample was divided according to structure richness, representing 10 richness classes, with the distribution of ellipticities differing among individual classes. Mean ellipticity varies from 0.34 to 0.18, less well populated structures being more elongated that richer ones. Statistics indicate that structures with at least 50 members originate from the same population. The mean redshift of a structure class is a function of richness, with less well populated classes exhibiting greater mean redshifts than richer galaxy clusters. Further analysis reveals a dependence of the ellipticity-redshift correlation on structure richness. Among rich galaxy clusters there is an anti-correlation between the parameters, the strongest correlation occurring for the most poorly populated galaxy classes.

  1. Surface Brightness-dependent Clustering of APM Galaxies

    NASA Astrophysics Data System (ADS)

    Shao, Z.

    Based on a simple estimation of surface brightness (SB) of galaxies in the Automated Plate Measuring Machine (APM) catalogue, a homogeneous sample of apparent central SB data for more than 2 million galaxies brighter than BJ=20.5, covering 4300 deg2 in the region of the south galactic cap, was taken account to investigate the dependence of the strength of galaxy clustering on SB. The two point correlation function was used to compare the clustering pattern of galaxies in a series of SB volume-limited samples. Galaxies with high SB were found to have a significantly strong clustering strength in comparison to normal and low SB galaxies.

  2. Galaxy formation

    SciTech Connect

    Silk, J.

    1984-11-01

    Implications of the isotropy of the cosmic microwave background on large and small angular scales for galaxy formation are reviewed. In primeval adiabatic fluctuations, a universe dominated by cold, weakly interacting nonbaryonic matter, e.g., the massive photino is postulated. A possible signature of photino annihilation in our galactic halo involves production of cosmic ray antiprotons. If the density is near its closure value, it is necessary to invoke a biasing mechanism for suppressing galaxy formation throughout most of the universe in order to reconcile the dark matter density with the lower astronomical determinations of the mean cosmological density. A mechanism utilizing the onset of primordial massive star formation to strip gaseous protogalaxies is described. Only the densest, early collapsing systems form luminous galaxies. (ESA)

  3. Isolated galaxies: residual of primordial building blocks?

    NASA Astrophysics Data System (ADS)

    Galletta, G.; Rodighiero, G.; Bettoni, D.; Moles, M.; Varela, J.

    2006-09-01

    Context: .The mass assembly is believed to be the dominant process of early galaxy formation. This mechanism of galaxy building can proceed either by repeated major mergers with other systems, or by means of accretion of matter from the surrounding regions. Aims: .In this paper we compare the properties of local disk galaxies that appear isolated, i.e., not tidally affected by other galaxies during the last few Gyr within the volume given by cz≤ 5000 km s-1, with those galaxies at z values from 0.25 to 5. Methods: .Effective radii for 203 isolated galaxies and 1645 galaxies from the RC3 have been collected and the two samples have been analyzed statistically. A similar comparison has been made with half light radii studied at high z from the literature. Results: .We found that isolated galaxies are, in general, smaller than other present epoch galaxies from the RC3. We notice the lack of systems larger than 7 kpc among them. Their size distribution appears to be similar to that of galaxies at 1.4 ≤ z ≤ 2. The models of the merging history also indicate that the isolated galaxies did stop their merging process at about that redshift, evolving passively since then. The galaxy density seems to have remained unchanged since that epoch Conclusions: .Isolated galaxies appear to be the end products of the merging process, as proposed by the hierarchical accretion scenario at around z=1.4. For this class of galaxies, this was the last significant merging event in their lives, and they have evolved passively since then. This is confirmed by the analytical estimate of the merging fraction with z and by the comparison with sizes of distant galaxies.

  4. The VRI colours of H II galaxies

    NASA Astrophysics Data System (ADS)

    Telles, Eduardo; Terlevich, Roberto

    1997-03-01

    We present a high spatial resolution CCD surface photometry study in the optical V, R and I broad-band filters of a sample of 15 H II galaxies. Narrow-band imaging allows the separation of the emission-line region from the extended parts of the galaxy. The latter are assumed to represent the underlying galaxy in H II galaxies; thus the colours of the underlying galaxy are measured. The colours of the underlying stellar continuum within the starburst are also derived by subtracting the contribution of the emission lines falling in the broad-band filters. The distribution of colours of the underlying galaxy in H II galaxies is similar to the colours of other late-type low surface brightness galaxies, which suggests a close kinship of these with the quiescent phases of H II galaxies. However, comparison wtih recent evolutionary population synthesis models shows that the observational errors and the uncertainties in the models are still too large to put strict constraints on their past star formation history. Our analysis of the morphology and structural properties, from contour maps and luminosity profiles, of this sample of 15 H II galaxies agrees with what has been found by Telles and Telles, Melnick & Terlevich, namely that H II galaxies comprise two broad classes segregated by their luminosity; Type I H II galaxies are luminous and have disturbed and irregular outer shapes, while Type II H II galaxies are less luminous and have regular shapes. The outer parts of their profiles are well represented by an exponential, as in other types of known dwarf galaxy.

  5. Whirlpool Galaxy

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Scientists are seeing unprecedented detail of the spiral arms and dust clouds in the nearby Whirlpool galaxy, thanks to a new Hubble Space Telescope image, available at http://www.jpl.nasa.gov/pictures/wfpc/wfpc.html. The image uses data collected January 15 and 24, 1995, and July 21, 1999, by Hubble's Wide Field and Planetary Camera 2, designed and built by JPL. Using the image, a research group led by Dr. Nick Scoville of the California Institute of Technology, Pasadena, clearly defined the structure of the galaxy's cold dust clouds and hot hydrogen, and they linked star clusters within the galaxy to their parent dust clouds.

    The Whirlpool galaxy is one of the most photogenic galaxies. This celestial beauty is easily seen and photographed with smaller telescopes and studied extensively from large ground- and space-based observatories. The new composite image shows visible starlight and light from the emission of glowing hydrogen, which is associated with the most luminous young stars in the spiral arms.

    The galaxy is having a close encounter with a nearby companion galaxy, NGC 5195, just off the upper edge of the image. The companion's gravitational pull is triggering star formation in the main galaxy, lit up by numerous clusters of young and energetic stars in brilliant detail. Luminous clusters are highlighted in red by their associated emission from glowing hydrogen gas.

    This image was composed by the Hubble Heritage Team from Hubble archive data and was superimposed onto data taken by Dr. Travis Rector of the National Optical Astronomy Observatory at the .9-meter (35-inch) telescope at the National Science Foundation's Kitt Peak National Observatory, Tucson, Ariz. Scoville's team includes M. Polletta of the University of Geneva, Switzerland; S. Ewald and S. Stolovy of Caltech; and R. Thompson and M. Rieke of the University of Arizona, Tucson.

    The Space Telescope Science Institute, Baltimore, Md., manages space operations for the Hubble Space

  6. Whirlpool Galaxy

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Scientists are seeing unprecedented detail of the spiral arms and dust clouds in the nearby Whirlpool galaxy, thanks to a new Hubble Space Telescope image, available at http://www.jpl.nasa.gov/pictures/wfpc/wfpc.html. The image uses data collected January 15 and 24, 1995, and July 21, 1999, by Hubble's Wide Field and Planetary Camera 2, designed and built by JPL. Using the image, a research group led by Dr. Nick Scoville of the California Institute of Technology, Pasadena, clearly defined the structure of the galaxy's cold dust clouds and hot hydrogen, and they linked star clusters within the galaxy to their parent dust clouds.

    The Whirlpool galaxy is one of the most photogenic galaxies. This celestial beauty is easily seen and photographed with smaller telescopes and studied extensively from large ground- and space-based observatories. The new composite image shows visible starlight and light from the emission of glowing hydrogen, which is associated with the most luminous young stars in the spiral arms.

    The galaxy is having a close encounter with a nearby companion galaxy, NGC 5195, just off the upper edge of the image. The companion's gravitational pull is triggering star formation in the main galaxy, lit up by numerous clusters of young and energetic stars in brilliant detail. Luminous clusters are highlighted in red by their associated emission from glowing hydrogen gas.

    This image was composed by the Hubble Heritage Team from Hubble archive data and was superimposed onto data taken by Dr. Travis Rector of the National Optical Astronomy Observatory at the .9-meter (35-inch) telescope at the National Science Foundation's Kitt Peak National Observatory, Tucson, Ariz. Scoville's team includes M. Polletta of the University of Geneva, Switzerland; S. Ewald and S. Stolovy of Caltech; and R. Thompson and M. Rieke of the University of Arizona, Tucson.

    The Space Telescope Science Institute, Baltimore, Md., manages space operations for the Hubble Space