Showing papers by "Antonio Cava published in 2013"
INAF1, University of Bologna2, University of Padua3, Max Planck Society4, University of Provence5, Open University6, University of Trieste7, University of Sussex8, University of Edinburgh9, University of the Western Cape10, Spanish National Research Council11, Federal University of Rio de Janeiro12, University of Cambridge13, Ames Research Center14, California Institute of Technology15, Jet Propulsion Laboratory16, University of La Laguna17, Complutense University of Madrid18, Imperial College London19, University of Colorado Boulder20, University of California, Irvine21, Goddard Space Flight Center22, Cardiff University23, UK Astronomy Technology Centre24, European Space Research and Technology Centre25, University of Paris-Sud26, University of Manchester27, University College London28, Rutherford Appleton Laboratory29, University of Lethbridge30, University of Oxford31, University of British Columbia32, Commonwealth Scientific and Industrial Research Organisation33, University of Hertfordshire34, Harvard University35, Institut d'Astrophysique de Paris36, École Polytechnique Fédérale de Lausanne37, University of Toulouse38
TL;DR: In this article, the authors exploit the deep and extended far-IR data sets (at 70, 100 and 160 μm) of the GPS PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 μm, to derive the evolution of the rest-frame 35-, 60-, 90- and total infrared luminosity functions (LFs) up to z ∼ 4.
Abstract: We exploit the deep and extended far-IR data sets (at 70, 100 and 160 μm) of the Herschel Guaranteed Time Observation (GTO) PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 μm, to derive the evolution of the rest-frame 35-, 60-, 90- and total infrared (IR) luminosity functions (LFs) up to z ∼ 4. We detect very strong luminosity evolution for the total IR LF (LIR ∝ (1 + z)3.55 ± 0.10 up to z ∼ 2, and ∝ (1 + z)1.62 ± 0.51 at 2 < z ≲ 4) combined with a density evolution (∝(1 + z)−0.57 ± 0.22 up to z ∼ 1 and ∝ (1 + z)−3.92 ± 0.34 at 1 < z ≲ 4). In agreement with previous findings, the IR luminosity density (ρIR) increases steeply to z ∼ 1, then flattens between z ∼ 1 and z ∼ 3 to decrease at z ≳ 3. Galaxies with different spectral energy distributions, masses and specific star formation rates (SFRs) evolve in very different ways and this large and deep statistical sample is the first one allowing us to separately study the different evolutionary behaviours of the individual IR populations contributing to ρIR. Galaxies occupying the well-established SFR–stellar mass main sequence (MS) are found to dominate both the total IR LF and ρIR at all redshifts, with the contribution from off-MS sources (≥0.6 dex above MS) being nearly constant (∼20 per cent of the total ρIR) and showing no significant signs of increase with increasing z over the whole 0.8 < z < 2.2 range. Sources with mass in the range 10 ≤ log(M/M⊙) ≤ 11 are found to dominate the total IR LF, with more massive galaxies prevailing at the bright end of the high-z (≳2) LF. A two-fold evolutionary scheme for IR galaxies is envisaged: on the one hand, a starburst-dominated phase in which the Super Massive Black Holes (SMBH) grows and is obscured by dust (possibly triggered by a major merging event), is followed by an AGN-dominated phase, then evolving towards a local elliptical. On the other hand, moderately star-forming galaxies containing a low-luminosity AGN have various properties suggesting they are good candidates for systems in a transition phase preceding the formation of steady spiral galaxies.
461 citations
University of California, Irvine1, California Institute of Technology2, Ames Research Center3, University of Edinburgh4, Paris Diderot University5, Rutgers University6, University of Paris-Sud7, Harvard University8, Jet Propulsion Laboratory9, Aix-Marseille University10, University of La Laguna11, Spanish National Research Council12, University of Hawaii13, Complutense University of Madrid14, European Space Agency15, University of Cambridge16, Imperial College London17, University of Colorado Boulder18, University of Nottingham19, Cardiff University20, Virginia Tech21, University of Sussex22, University of Padua23, First Green Bank24, Institut d'Astrophysique de Paris25, University of Maryland, College Park26, UK Astronomy Technology Centre27, University of British Columbia28, University College London29, Rutherford Appleton Laboratory30, Open University31, University of Oxford32, Commonwealth Scientific and Industrial Research Organisation33, University of the Western Cape34
TL;DR: In this paper, the authors presented a list of 13 candidate gravitationally lensed submillimeter galaxies (SMGs) from 95 deg^2 of the Herschel Multi-tiered Extragalactic Survey, a surface density of 0.14 ± 0.04 deg^(
Abstract: We present a list of 13 candidate gravitationally lensed submillimeter galaxies (SMGs) from 95 deg^2 of the Herschel Multi-tiered Extragalactic Survey, a surface density of 0.14 ± 0.04 deg^(–2). The selected sources have 500 μm flux densities (S_(500)) greater than 100 mJy. Gravitational lensing is confirmed by follow-up observations in 9 of the 13 systems (70%), and the lensing status of the four remaining sources is undetermined. We also present a supplementary sample of 29 (0.31 ± 0.06 deg^(–2)) gravitationally lensed SMG candidates with S_(500) = 80-100 mJy, which are expected to contain a higher fraction of interlopers than the primary candidates. The number counts of the candidate lensed galaxies are consistent with a simple statistical model of the lensing rate, which uses a foreground matter distribution, the intrinsic SMG number counts, and an assumed SMG redshift distribution. The model predicts that 32%-74% of our S_(500) ≥ 100 mJy candidates are strongly gravitationally lensed (μ ≥ 2), with the brightest sources being the most robust; this is consistent with the observational data. Our statistical model also predicts that, on average, lensed galaxies with S_(500) = 100 mJy are magnified by factors of ~9, with apparently brighter galaxies having progressively higher average magnification, due to the shape of the intrinsic number counts. 65% of the sources are expected to have intrinsic 500 μm flux densities less than 30 mJy. Thus, samples of strongly gravitationally lensed SMGs, such as those presented here, probe below the nominal Herschel detection limit at 500 μm. They are good targets for the detailed study of the physical conditions in distant dusty, star-forming galaxies, due to the lensing magnification, which can lead to spatial resolutions of ~0."01 in the source plane.
193 citations
University of California, Irvine1, UK Astronomy Technology Centre2, Cornell University3, Harvard University4, University of Maryland, College Park5, European Space Agency6, Paris Diderot University7, Rutgers University8, Jet Propulsion Laboratory9, California Institute of Technology10, University of Hawaii11, Complutense University of Madrid12, Dalhousie University13, Imperial College London14, University of Colorado Boulder15, Virginia Tech16, National Radio Astronomy Observatory17, University of Oxford18, University of British Columbia19, University of La Laguna20, Spanish National Research Council21, INAF22, University of Sussex23, Institut d'Astrophysique de Paris24, University College London25, University of the Western Cape26
TL;DR: It is concluded that gas-rich major galaxy mergers with intense star formation can form the most massive elliptical galaxies by z ≈ 1.5.
Abstract: Stellar archaeology shows that massive elliptical galaxies formed rapidly about ten billion years ago with star-formation rates of above several hundred solar masses per year. Their progenitors are probably the submillimetre bright galaxies at redshifts z greater than 2. Although the mean molecular gas mass (5 × 10(10) solar masses) of the submillimetre bright galaxies can explain the formation of typical elliptical galaxies, it is inadequate to form elliptical galaxies that already have stellar masses above 2 × 10(11) solar masses at z ≈ 2. Here we report multi-wavelength high-resolution observations of a rare merger of two massive submillimetre bright galaxies at z = 2.3. The system is seen to be forming stars at a rate of 2,000 solar masses per year. The star-formation efficiency is an order of magnitude greater than that of normal galaxies, so the gas reservoir will be exhausted and star formation will be quenched in only around 200 million years. At a projected separation of 19 kiloparsecs, the two massive starbursts are about to merge and form a passive elliptical galaxy with a stellar mass of about 4 × 10(11) solar masses. We conclude that gas-rich major galaxy mergers with intense star formation can form the most massive elliptical galaxies by z ≈ 1.5.
176 citations
Complutense University of Madrid1, University of Arizona2, University of California, Santa Cruz3, University College London4, University of La Laguna5, Spanish National Research Council6, Institut d'Astrophysique de Paris7, University of Nottingham8, Los Alamos National Laboratory9, Paris Diderot University10, University of Florida11, INAF12, Aix-Marseille University13
TL;DR: The Survey for High-z Absorption Red and Dead Sources (SHARDS) as mentioned in this paper is an ESO/GTC Large Program carried out using the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias (GTC).
Abstract: We present the Survey for High-z Absorption Red and Dead Sources (SHARDS), an ESO/GTC Large Program carried out using the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias (GTC). SHARDS is an ultra-deep optical spectro-photometric survey of the GOODS-N field covering 130 arcmin(2) at wavelengths between 500 and 950 nm with 24 contiguous medium-band filters (providing a spectral resolution R similar to 50). The data reach an AB magnitude of 26.5 (at least at a 3 sigma level) with sub-arcsec seeing in all bands. SHARDS' main goal is to obtain accurate physical properties of intermediate-and high-z galaxies using well-sampled optical spectral energy distributions (SEDs) with sufficient spectral resolution to measure absorption and emission features, whose analysis will provide reliable stellar population and active galactic nucleus (AGN) parameters. Among the different populations of high-z galaxies, SHARDS' principal targets are massive quiescent galaxies at z > 1, whose existence is one of the major challenges facing current hierarchical models of galaxy formation. In this paper, we outline the observational strategy and include a detailed discussion of the special reduction and calibration procedures which should be applied to the GTC/OSIRIS data. An assessment of the SHARDS data quality is also performed. We present science demonstration results on the detection and study of emission-line galaxies (star-forming objects and AGNs) at z = 0-5. We also analyze the SEDs for a sample of 27 quiescent massive galaxies with spectroscopic redshifts in the range 1.0 < z less than or similar to 1.4. We discuss the improvements introduced by the SHARDS data set in the analysis of their star formation history and stellar properties. We discuss the systematics arising from the use of different stellar population libraries, typical in this kind of study. Averaging the results from the different libraries, we find that the UV-to-MIR SEDs of the massive quiescent galaxies at z = 1.0-1.4 are well described by an exponentially decaying star formation history with scale t = 100-200 Myr, age around 1.5-2.0 Gyr, solar or slightly sub-solar metallicity, and moderate extinction, A(V) similar to 0.5 mag. We also find that galaxies with masses above M* are typically older than lighter galaxies, as expected in a downsizing scenario of galaxy formation. This trend is, however, model dependent, i.e., it is significantly more evident in the results obtained with some stellar population synthesis libraries, and almost absent in others.
125 citations
Pontifical Catholic University of Chile1, Science and Technology Facilities Council2, Leiden University3, Durham University4, University of Edinburgh5, Max Planck Society6, Paris Diderot University7, University of Paris-Sud8, California Institute of Technology9, Jet Propulsion Laboratory10, Complutense University of Madrid11, University of Colorado Boulder12, University of Sussex13, University of Hertfordshire14, University of Tokyo15, University of British Columbia16, University College London17, INAF18, Commonwealth Scientific and Industrial Research Organisation19, University of California, Irvine20
TL;DR: In this article, the authors describe the far-infrared (far-IR; rest-frame 8-1000-μm) properties of a sample of 443 Hα-selected star-forming galaxies in the Cosmic Evolution Survey (COSMOS) and Ultra Deep Survey (UDS) fields detected by the High-redshift Emission Line Survey (HiZELS) imaging survey.
Abstract: We describe the far-infrared (far-IR; rest-frame 8–1000-μm) properties of a sample of 443 Hα-selected star-forming galaxies in the Cosmic Evolution Survey (COSMOS) and Ultra Deep Survey (UDS) fields detected by the High-redshift Emission Line Survey (HiZELS) imaging survey. Sources are identified using narrow-band filters in combination with broad-band photometry to uniformly select Hα (and [O ii] if available) emitters in a narrow redshift slice at z = 1.47 ± 0.02. We use a stacking approach in Spitzer-MIPS mid-IR, Herschel-PACS/SPIRE far-IR [from the PACS Evolutionary Prove (PEP) and Herschel Multi-tiered Extragalactic Survey (HerMES)] and AzTEC mm-wave images to describe their typical far-IR properties. We find that HiZELS galaxies with observed Hα luminosities of L(Hα)_(obs) ≈ 10^(8.1-9.1) L_⊙ ( ≈ 10^(41.7-42.7) erg s^(−1)) have bolometric far-IR luminosities of typical luminous IR galaxies, L(8−1000μm)≈10^(11.41)^(+0.04)_(−0.06) L_⊙. Combining the Hα and far-IR luminosities, we derive median star formation rates (SFRs) of SFR_(Hα), FIR = 32 ± 5 M_⊙ yr^(−1) and Hα extinctions of A_(Hα) = 1.0 ± 0.2 mag. Perhaps surprisingly, little difference is seen in typical HiZELS extinction levels compared to local star-forming galaxies. We confirm previous empirical stellar mass (M_*) to A_(Hα) relations and the little or no evolution up to z = 1.47. For HiZELS galaxies (or similar samples) we provide an empirical parametrization of the SFR as a function of rest-frame (u − z) colours and 3.6-μm photometry – a useful proxy to aid in the absence of far-IR detections in high-z galaxies. We find that the observed Hα luminosity is a dominant SFR tracer when rest-frame (u − z) colours are ≲0.9 mag or when Spitzer-3.6-μm photometry is fainter than 22 mag (Vega) or when stellar masses are lower than 10^(9.7) M_⊙. We do not find any correlation between the [O ii]/Hα and far-IR luminosity, suggesting that this emission line ratio does not trace the extinction of the most obscured star-forming regions, especially in massive galaxies where these dominate. The luminosity-limited HiZELS sample tends to lie above of the so-called main sequence for star-forming galaxies, especially at low stellar masses, indicating high star formation efficiencies in these galaxies. This work has implications for SFR indicators and suggests that obscured star formation is linked to the assembly of stellar mass, with deeper potential wells in massive galaxies providing dense, heavily obscured environments in which stars can form rapidly.
72 citations
University of Padua1, University of the Western Cape2, INAF3, Max Planck Society4, California Institute of Technology5, Jet Propulsion Laboratory6, Aix-Marseille University7, Complutense University of Madrid8, Imperial College London9, University of California, Irvine10, University of Sussex11, Virginia Tech12, University of Cambridge13, University of Oxford14, University College London15, Rutherford Appleton Laboratory16, University of Edinburgh17, University of British Columbia18
TL;DR: In this paper, the authors combine far-infrared photometry from Herschel (PEP/HerMES) with deep midinfrared spectroscopy from Spitzer to investigate the nature and the mass assembly history of a sample of 31 luminous and ultraluminous infrared galaxies ((U)LIRGs) at z ~ 1 and 2 selected in GOODS-S with 24 μm fluxes between 0.2 and 0.5 mJy.
Abstract: We combine far-infrared photometry from Herschel (PEP/HerMES) with deep mid-infrared spectroscopy from Spitzer to investigate the nature and the mass assembly history of a sample of 31 luminous and ultraluminous infrared galaxies ((U)LIRGs) at z ~ 1 and 2 selected in GOODS-S with 24 μm fluxes between 0.2 and 0.5 mJy. We model the data with a self-consistent physical model (GRASIL) which includes a state-of-the-art treatment of dust extinction and reprocessing. We find that all of our galaxies appear to require massive populations of old (>1 Gyr) stars and, at the same time, to host a moderate ongoing activity of star formation (SFR ≤ 100 M_☉ yr^(–1)). The bulk of the stars appear to have been formed a few Gyr before the observation in essentially all cases. Only five galaxies of the sample require a recent starburst superimposed on a quiescent star formation history. We also find discrepancies between our results and those based on optical-only spectral energy distribution (SED) fitting for the same objects; by fitting their observed SEDs with our physical model we find higher extinctions (by ΔA_V ~ 0.81 and 1.14) and higher stellar masses (by Δlog(M_★) ~ 0.16 and 0.36 dex) for z ~ 1 and z ~ 2 (U)LIRGs, respectively. The stellar mass difference is larger for the most dust-obscured objects. We also find lower SFRs than those computed from L IR using the Kennicutt relation due to the significant contribution to the dust heating by intermediate-age stellar populations through "cirrus" emission (~73% and ~66% of the total L IR for z ~ 1 and z ~ 2 (U)LIRGs, respectively).
40 citations
TL;DR: In this paper, the authors report on results from the analysis of a stellar mass-selected (log (M-*/M-circle dot) >= 9.0) sample of 1644 galaxies at 0.65 11.
Abstract: We report on results from the analysis of a stellar mass-selected (log (M-*/M-circle dot) >= 9.0) sample of 1644 galaxies at 0.65 11, in agreement with downsizing scenarios.
33 citations
TL;DR: In this article, the authors investigated the role of the structure of galaxies and their stellar population in shaping and tilting the Fundamental Plane (FP) with respect to the virial plane (VP) expectation.
Abstract: By exploiting the database of early-type galaxies (ETGs) members of the WINGS survey of nearby clusters, we address here the long debated question of the origin and shape of the Fundamental Plane (FP). Our data suggest that different physical mechanisms concur in shaping and ’tilting’ the FP with respect to the virial plane (VP) expectation. In particular, an “hybrid solution” in which the structure of galaxies and their stellar population are the main contributors to the FP tilt seems to be favoured. We find that the bulk of the tilt should be attributed to structural non-homology, while stellar population effects play an important but less crucial role. In addition, our data indicate that the differential FP tilt between the V - and K-band is due to a sort of entanglement between structural and stellar population effects, for which the inward steepening of color profiles (V K) tends to increase at increasing the stellar mass of ETGs. The same kind of analysis applied to the ATLAS3D and SDSS data in common with WINGS (WSDSS throughout the paper) confirms our results, the only remarkable difference being the less important role that our data attribute to the stellar mass-to-light-ratio (stellar populations) in determining the FP tilt. The ATLAS3D data also suggest that the FP tilt depends as well on the dark matter (DM) fraction and on the rotational contribution to the kinetic energy (Vrot/σ), thus again pointing towards the above mentioned “hybrid solution”. We show that the global properties of the FP, i.e. its tilt and tightness, can be understood in terms of the underlying correlation among mass, structure and stellar population of ETGs, for which, at increasing the stellar mass, ETGs become (on average) ’older’ and more centrally concentrated. Finally, we show that a Malmquist-like selection effect may mimic a differential evolution of the mass-to-light ratio for galaxies of different masses. This should be taken into account in the studies investigating the amount of the so called “downsizing” phenomenon.
27 citations
Imperial College London1, University of Oxford2, University of Hertfordshire3, University of Nottingham4, University of St Andrews5, University of Western Australia6, University of Canterbury7, University of Tasmania8, University of Central Lancashire9, Cardiff University10, Ghent University11, Complutense University of Madrid12, University of California, Irvine13, INAF14, International School for Advanced Studies15, UK Astronomy Technology Centre16, University of Edinburgh17
TL;DR: In this article, the authors used multiwavelength (0.12-500µm) photometry from Herschel-ATLAS, WISE, UKIDSS, SDSS and GALEX to study 23 nearby spheroidal galaxies with prominent dust lanes.
Abstract: We use multiwavelength (0.12-500µm) photometry from Herschel-ATLAS, WISE, UKIDSS, SDSS and GALEX to study 23 nearby spheroidal galaxies with prominent dust lanes (DLSGs). DLSGs are considered to be remnants of recent minor mergers, making them ideal laboratories for studying both the interstellar medium (ISM) of spheroids and minor-merger-driven star formation in the nearby Universe. The DLSGs exhibit star formation rates (SFRs) between 0.01 and 10 Myr −1 , with a median of 0.26 Myr −1 (a factor of 3.5 greater than the average SG). The median dust mass, dust-to-stellar mass ratio and dust temperature in these galaxies are around 10 7.6 M� , ≈0.05 per cent and ≈19.5 K, respectively. The dust masses are at least a factor of 50 greater than that expected from stellar mass loss and, like the SFRs, show no correlation with galaxy luminosity, suggesting that both the ISM and the star formation have external drivers. Adopting literature gas-to-dust ratios and star formation histories derived from fits to the panchromatic photometry, we estimate that the median current and initial gas- to-stellar mass ratios in these systems are ≈4 and ≈7 per cent, respectively. If, as indicated by recent work, minor mergers that drive star formation in spheroids with (NUV − r) > 3. 8( the colour range of our DLSGs) have stellar mass ratios between 1:6 and 1:10, then the satellite gas fractions are likely ≥50 per cent.
19 citations
TL;DR: In this paper, the authors used the near-IR or optical images directly for position priors to identify and extract the major contributors of a large number of Herschel FIR sources.
Abstract: The Herschel very wide-field surveys have charted hundreds of square degrees in multiple far-IR (FIR) bands. While the Sloan Digital Sky Survey (SDSS) is currently the best resource for optical counterpart identifications over such wide areas, it does not detect a large number of Herschel FIR sources and leaves their nature undetermined. As a test case, we studied seven "SDSS-invisible", very bright 250um sources (S_{250} > 55 mJy) in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) fields where we have a rich multi-wavelength data set. We took a new approach to decompose the FIR sources, using the near-IR or the optical images directly for position priors. This is an improvement over the previous decomposition efforts where the priors are from mid-IR data that still suffer from the source blending problem in the first place. We found that in most cases the single Herschel sources are made of multiple components that are not necessarily at the same redshifts. Our decomposition succeeded in identifying and extracting their major contributors. We show that these are all ULIRGs at z ~ 1--2 whose high L_IR is mainly due to dust-obscured star formation. Most of them would not be selected as sub-mm galaxies. They all have complicated morphologies indicative of merger or violent instability, and their stellar populations are heterogeneous in terms of stellar masses, ages and formation histories. Their current ULIRG phases are of various degrees of importance in their stellar mass assembly. Our practice provides a promising starting point to develop an automatic routine to reliably study bright Herschel sources.
18 citations
TL;DR: In this paper, the WINGS project has collected wide field, optical (B,V) and near-infrared (J,K) imaging, as well as medium resolution spectroscopy of galaxies in a sample of 76 X-ray selected nearby clusters (0.04 < z < 0.07).
Abstract: This paper belongs to a series presenting the WIde Field Nearby Galaxy-cluster Survey (WINGS). The WINGS project has collected wide-field, optical (B,V) and near-infrared (J,K) imaging, as well as medium resolution spectroscopy of galaxies in a sample of 76 X-ray selected nearby clusters (0.04 < z < 0.07), with the aim of establishing a reference sample for evolutionary studies of galaxies and galaxy clusters. In this paper we present the U-band photometry of galaxies and stars in the fields of 17 clusters of the WINGS sample. We also extend to a larger field of view the original B- and V-band photometry (WINGS-OPT) for 9 and 6 WINGS clusters, respectively. We use both the new and the already existing B-band photometry to get reliable (U-B) colors of galaxies within three fixed apertures in kpc. To this aim, in the reduction procedure we put particular care in the astrometric precision. Since not all the observations have been taken in good transparency conditions, the photometric calibration was partly obtained relying on the SDSS and WINGS-OPT photometry for the U- and optical bands, respectively. We provide U-band (also B- and V-band, where possible) total magnitudes of stars and galaxies in the fields of clusters. Just for galaxies, the catalogs also provide geometrical parameters and carefully centered aperture magnitudes. The internal consistency of magnitudes has been checked for clusters imaged with different cameras, while the external photometric consistency has been obtained comparing with the WINGS-OPT and SDSS surveys. The photometric catalogs presented here add the U-band information to the WINGS database for extending the SED of the galaxies, in particular in the UV wavelengths which are fundamental for deriving the SFR properties.
University of Hertfordshire1, University of the Western Cape2, University of Nottingham3, Ghent University4, Australian Astronomical Observatory5, Complutense University of Madrid6, University of California, Irvine7, Imperial College London8, International School for Advanced Studies9, INAF10, University of Canterbury11, Cardiff University12, Open University13, UK Astronomy Technology Centre14, University of Edinburgh15, European Southern Observatory16, University of Sussex17
TL;DR: In this paper, the authors compare the environmental and star formation properties of far-infrared detected and non-far-inrared detected galaxies out to z ˜ 0.5sigma level.
Abstract: We compare the environmental and star formation properties of far-infrared detected and non-far-infrared detected galaxies out to z ˜ 0.5. Using optical spectroscopy and photometry from the Galaxy And Mass Assembly (GAMA) and Sloan Digital Sky Survey, with far-infrared observations from the Herschel Astrophysical Terahertz Large Area Survey (ATLAS) Science Demonstration Phase, we apply the technique of Voronoi tessellations to analyse the environmental densities of individual galaxies. Applying statistical analyses to colour, r-band magnitude and redshift-matched samples, we show that there is a significant difference at the 3.5sigma level between the normalized environmental densities of these two populations. This is such that infrared emission (a tracer of star formation activity) favours underdense regions compared to those inhabited by exclusively optically observed galaxies selected to be of the same r-band magnitude, colour and redshift. Thus, more highly star-forming galaxies are found to reside in the most underdense environments, confirming previous studies that have proposed such a correlation. However, the degeneracy between redshift and far-infrared luminosity in our flux-density-limited sample means that we are unable to make a stronger statement in this respect. We then apply our method to synthetic light cones generated from semi-analytic models, finding that over the whole redshift distribution the same correlations between star formation rate and environmental density are found.
University of Bologna1, University of Padua2, Max Planck Society3, European Southern Observatory4, Aix-Marseille University5, Open University6, University of Sussex7, University of the Western Cape8, Federal University of Rio de Janeiro9, INAF10, University of Cambridge11, Ames Research Center12, California Institute of Technology13, University of La Laguna14, Complutense University of Madrid15, Imperial College London16, University of Colorado Boulder17, University of California, Irvine18, Goddard Space Flight Center19, Cardiff University20, European Space Research and Technology Centre21, University of Paris-Sud22, University of Manchester23, University College London24, Rutherford Appleton Laboratory25, University of Lethbridge26, University of Oxford27, University of British Columbia28, Commonwealth Scientific and Industrial Research Organisation29, University of Hertfordshire30, Harvard University31, University of Paris32, ETH Zurich33, University of Toulouse34
TL;DR: In this article, the authors exploit the deep and extended far-IR data sets (at 70, 100 and 160 μm) of the GPS PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 μm, to derive the evolution of the rest-frame 35-, 60-, 90and total infrared luminosity functions (LFs) up to z ∼ 4.
Abstract: We exploit the deep and extended far-IR data sets (at 70, 100 and 160 μm) of the Herschel Guaranteed Time Observation (GTO) PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 μm, to derive the evolution of the rest-frame 35-, 60-, 90and total infrared (IR) luminosity functions (LFs) up to z ∼ 4. We detect very strong luminosity evolution for the total IR LF (LIR ∝ (1 + z)3.55 ± 0.10 up to z ∼ 2, and ∝ (1 + z)1.62 ± 0.51 at 2 < z 4) combined with a density evolution (∝ (1 + z)−0.57 ± 0.22 up to z ∼ 1 and ∝ (1 + z)−3.92 ± 0.34 at 1 < z 4). In agreement with previous findings, the IR luminosity density (ρIR) increases steeply to z ∼ 1, then flattens between z ∼ 1 and z ∼ 3 to decrease at z 3. Galaxies with different spectral energy distributions, masses and specific star formation rates (SFRs) evolve in very different ways and this large and deep statistical sample is the first one allowing us to separately study the different evolutionary behaviours of the individual IR populations contributing to ρIR. Galaxies occupying the well-established SFR–stellar mass main sequence (MS) are found to dominate both the total IR LF and ρIR at all redshifts, with the contribution from off-MS sources (≥0.6 dex above MS) being nearly constant (∼20 per cent of the total ρIR) and showing no significant signs of increase with increasing z over the whole 0.8 < z < 2.2 range. Sources with mass in the range 10 ≤ log(M/M ) ≤ 11 are found to dominate the total IR LF, with more massive galaxies prevailing at the bright end of the high-z ( 2) LF. A two-fold evolutionary scheme for IR galaxies is envisaged: on the one hand, a starburst-dominated phase in which the Super Massive Black Holes (SMBH) grows and is obscured by dust (possibly triggered by a major merging event), is followed by an AGN-dominated phase, then evolving towards a local elliptical. On the other hand, moderately star-forming galaxies containing a low-luminosity AGN have various properties suggesting they are good candidates for systems in a transition phase preceding the formation of steady spiral galaxies.
TL;DR: In this paper, the growth curves and surface brightness light profiles of the clusters of the WINGS sample were analyzed in the B and V bands, measuring the effective radii, the effective surface brightnesses and the total luminosities of our clusters.
Abstract: We have analyzed the growth curves and the surface brightness light profiles of the clusters of the WINGS sample (Fasano et al. 2006) in the B and V bands, measuring the effective radii, the effective surface brightnesses and the total luminosities of our clusters. The similarly of the radial surface brightness profiles of early-type galaxies (ETGs) and clusters indicate that within r200 almost all clusters are virialized structures. The total luminosities LB of clusters are found to correlate with the X-ray luminosity LX, following approximately the same relation measured for galaxies by Eskridge et al. (1995). By coupling the photometric data with the central velocity dispersions, derived from the radial velocities of the galaxies measured by Cava et al. (2009), we were able to fit the fundamental plane (FP) of clusters of galaxies. We find that it has approximately the same slope of the FPs of early-type galaxies (ETGs) and globular clusters (GCs), but differs from them in the zero-point. This behavior can be easily explained in terms of a different contribution of dark matter (DM). (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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TL;DR: In this article, the stellar populations and star formation activity in the host galaxies of X-ray selected optically faint AGN at 0.6 10^10.5 Mo were studied.
Abstract: SHARDS is an ongoing ESO/GTC large program that is obtaining ultra-deep photometry of the GOODS-North field in 24 medium-band filters (reaching m=26.5 AB in all bands) in the 500-950 nm range with GTC/OSIRIS. It is designed to study the properties of high-z massive galaxies, but it can also provide very valuable information about the population of AGN at intermediate redshifts (z~0.5-2). Here we present preliminary results on a study of the stellar populations and star formation activity in the host galaxies of X-ray selected optically faint AGN at 0.6 10^10.5 Mo) and that the fraction of galaxies hosting an AGN increases with the stellar mass. AGN-hosts have restframe U-V and Dn(4000) comparable to those of non-active galaxies of the same mass, that is, they do not appear to have on average younger stellar populations, unlike in the Local Universe. Nevertheless, z~1 AGN hosts show an excess of IR emission at {\lambda}>3{\mu}m compared to non-AGN galaxies which might indicate increased star formation rates. In addition, the frequency of AGN in massive galaxies is about twice higher for the ones with young stellar populations compared to the older ones.