We present new constraints on the relationship between galaxies and their host dark matter haloes, measured from the location of the peak of the stellar-to-halo mass ratio (SHMR), up to the most ...massive galaxy clusters at redshift z ∼ 0.8 and over a volume of nearly 0.1 Gpc3. We use a unique combination of deep observations in the CFHTLenS/VIPERS field from the near-UV to the near-IR, supplemented by ∼60 000 secure spectroscopic redshifts, analysing galaxy clustering, galaxy–galaxy lensing and the stellar mass function. We interpret our measurements within the halo occupation distribution (HOD) framework, separating the contributions from central and satellite galaxies. We find that the SHMR for the central galaxies peaks at
$M_{\rm h, peak} = 1.9^{+0.2}_{-0.1}\times 10^{12}{\,{\rm M}_{{\odot }}}$
with an amplitude of 0.025, which decreases to ∼0.001 for massive haloes (
${{{M}_{\rm h}}}> 10^{14} {\,{\rm M}_{{\odot }}}$
). Compared to central galaxies only, the total SHMR (including satellites) is boosted by a factor of 10 in the high-mass regime (cluster-size haloes), a result consistent with cluster analyses from the literature based on fully independent methods. After properly accounting for differences in modelling, we have compared our results with a large number of results from the literature up to z = 1: we find good general agreement, independently of the method used, within the typical stellar-mass systematic errors at low to intermediate mass (
${{{M}_{\rm \star }}}<10^{11} {\,{\rm M}_{{\odot }}}$
) and the statistical errors above. We have also compared our SHMR results to semi-analytic simulations and found that the SHMR is tilted compared to our measurements in such a way that they over- (under-) predict star formation efficiency in central (satellite) galaxies.
In this paper we describe the first data release of the UltraVISTA near-infrared imaging survey of the COSMOS field. We summarise the key goals and design of the survey and provide a detailed ...description of our data reduction techniques. We provide stacked, sky-subtracted images in YJHKs and narrow-band filters constructed from data collected during the first year of UltraVISTA observations. Our stacked images reach 5σAB depths in an aperture of 2″ diameter of ~25 in Y and ~24 in JHKs bands and all have sub-arcsecond seeing. To this 5σ limit, our Ks catalogue contains 216 268 sources. We carry out a series of quality assessment tests on our images and catalogues, comparing our stacks with existing catalogues. The 1σ astrometric rms in both directions for stars selected with 17.0 < Ks(AB) < 19.5 is ~0.08″ in comparison to the publicly-available COSMOS ACS catalogues. Our images are resampled to the same pixel scale and tangent point as the publicly available COSMOS data and so may be easily used to generate multi-colour catalogues using this data. All images and catalogues presented in this paper are publicly available through ESO’s “phase 3” archiving and distribution system and from the UltraVISTA web site.
The VIPERS Multi-Lambda Survey Moutard, T; Arnouts, S; Ilbert, O ...
Astronomy and astrophysics (Berlin),
6/2016, Volume:
590
Journal Article
Peer reviewed
Open access
We investigate the evolution of the galaxy stellar mass function and stellar mass density from redshift z= 0.2 to z= 1.5 of a K sub(s)< 22-selected sample with highly reliable photometric redshifts ...and over an unprecedentedly large area. Our study is based on near-infrared observations carried out with the WIRCam instrument at CFHT over the footprint of the VIPERS spectroscopic survey and benefits from the high-quality optical photometry from the CFHTLS and ultraviolet observations with the GALEX satellite. The accuracy of our photometric redshifts is sigma sub(Delta)z/ (1 + z)< 0.03 and 0.05 for the bright (i sub(AB)< 22.5) and faint (i sub(AB)> 22.5) samples, respectively. The galaxy stellar mass function is measured with ~760000 galaxies down to K sub(s)~ 22 and over an effective area of ~22.4 deg super(2), the latter of which drastically reduces the statistical uncertainties (i.e. Poissonian error and cosmic variance). We point out the importance of carefully controlling the photometric calibration, whose effect becomes quickly dominant when statistical uncertainties are reduced, which will be a major issue for future cosmological surveys with EUCLID or LSST, for instance. By exploring the rest-frame (NUV?r) vs. (r?K sub(s)) colour-colour diagram with which we separated star-forming and quiescent galaxies, (1) we find that the density of very massive log(M sub(?)/M sub(?)) > 11.5 galaxies is largely dominated by quiescent galaxies and increases by a factor 2 from z~ 1 to z~ 0.2, which allows for additional mass assembly through dry mergers. (2) We also confirm the scenario in which star formation activity is impeded above a stellar mass log(? super(*) sub(SF)/M sub(?)) = 10.64+ or -0.01. This value is found to be very stable at 0.2 <z< 1.5. (3) We discuss the existence of a main quenching channel that is followed by massive star-forming galaxies, and we finally (4) characterise another quenching mechanism that is required to explain the clear excess of low-mass quiescent galaxies that is observed at low redshift.
The VIPERS Multi-Lambda Survey Moutard, T; Arnouts, S; Ilbert, O ...
Astronomy and astrophysics (Berlin),
06/2016, Volume:
590
Journal Article
Peer reviewed
Open access
We present observations collected in the CFHTLS-VIPERS region in the ultraviolet with the GALEX satellite (far- and near-ultraviolet channels) and in the near-infrared with the CFHT/WIRCam camera (K ...sub(s) band) over an area of 22 and 27 deg super(2), respectively. The depth of the photometry was optimised to measure the physical properties (e.g., star formation rate, stellar masses) of all the galaxies in the VIPERS spectroscopic survey. The large volume explored by VIPERS will enable a unique investigation of the relationship between the galaxy properties and their environment (density field and cosmic web) at high redshift (0.5 < or = z< or = 1.2). In this paper, we present the observations, the data reductions, and the build-up of the multi-colour catalogues. The CFHTLS-T0007 (gri-chi super(2)) images are used as reference to detect and measure the K sub(s)-band photometry, while the T0007 u super(+ or -)-selected sources are used as priors to perform the GALEX photometry based on a dedicated software (EMphot). Our final sample reaches NUV sub(AB)~ 25 (at 5sigma) and K sub(AB)~ 22 (at 3sigma). The large spectroscopic sample (~51000 spectroscopic redshifts) allows us to highlight the robustness of our star/galaxy separation and the reliability of our photometric redshifts with a typical accuracy of sigma sub(z)< or = 0.04 and a fraction of catastrophic failures eta< or = 2% down to i~ 23. We present various tests on the K sub(s)-band completeness and photometric redshift accuracy by comparing our results with existing overlapping deep photometric catalogues. Finally, we discuss the BzK sample of passive and active galaxies at high redshift and the evolution of galaxy morphology in the (NUV-r) vs. (r-K sub(s)) diagram at low redshift (z< or = 0.25) based on the high image quality of the CFHTLS.
It has become increasingly apparent that studying how dark matter haloes are populated by galaxies can provide new insights into galaxy formation and evolution. In this paper, we present a detailed ...investigation of the changing relationship between galaxies and the dark matter haloes they inhabit from z ~ 1.2 to the present day. We do this by comparing precise galaxy clustering measurements over 133 deg2 of the “Wide” component of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) with predictions of an analytic halo occupation distribution (HOD) model where the number of galaxies in each halo depends only on the halo mass. Starting from a parent catalogue of ~3 × 106 galaxies at i′AB<22.5 we use accurate photometric redshifts calibrated using ~104 spectroscopic redshifts to create a series of type-selected volume-limited samples covering 0.2 < z < 1.2. Our principal result, based on clustering measurements in these samples, is a robust determination of the luminosity-to-halo mass ratio and its dependence on redshift and galaxy type. For the full sample, this reaches a peak at low redshifts of Mhpeak = 4.5×1011 h-1 M⊙ and moves towards higher halo masses at higher redshifts. For redder galaxies the peak is at higher halo masses and does not evolve significantly over the entire redshift range of our survey. We also consider the evolution of bias, average halo mass and the fraction of satellites as a function of redshift and luminosity. Our observed growth of a factor of ~2 in satellite fraction between z ~ 1 and z ~ 0 is testament to the limited role that galaxy merging plays in galaxy evolution for ~1012 h-1 M⊙ mass haloes at z < 1. Qualitatively, our observations are consistent with a picture in which red galaxies in massive haloes have already accumulated most of their stellar mass by z ~ 1 and subsequently undergo little evolution until the present day. The observed movement of the peak location for the full galaxy population is consistent with the bulk of star-formation activity migrating from higher mass haloes at high redshifts to lower mass haloes at lower redshifts.
Aims. We compute photometric redshifts in the fourth public release of the Canada-France-Hawaii Telescope Legacy Survey. This unique multi-colour catalogue comprises $u^*, g', r', i', z'$ photometry ...in four deep fields of 1 deg2 each and 35 deg2 distributed over three wide fields. Methods. We used a template-fitting method to compute photometric redshifts calibrated with a large catalogue of 16 983 high-quality spectroscopic redshifts from the VVDS-F02, VVDS-F22, DEEP2, and the zCOSMOS surveys. The method includes correction of systematic offsets, template adaptation, and the use of priors. We also separated stars from galaxies using both size and colour information. Results. Comparing with galaxy spectroscopic redshifts, we find a photometric redshift dispersion, $\sigma_{\Delta z/(1+z_{\rm s})}$, of 0.028–0.30 and an outlier rate, $|\Delta z| \ge 0.15\times (1+z_{\rm s})$, of 3–4% in the deep field at $i'_{\rm AB}$ < 24. In the wide fields, we find a dispersion of 0.037–0.039 and an outlier rate of 3–4% at $i'_{\rm AB}$ < 22.5. Beyond $i'_{\rm AB}$ = 22.5 in the wide fields the number of outliers rises from 5% to 10% at $i'_{\rm AB}$ < 23 and $i'_{\rm AB}$ < 24, respectively. For the wide sample the systematic redshift bias stays below 1% to $i'_{\rm AB}$ < 22.5, whereas we find no significant bias in the deep fields. We investigated the effect of tile-to-tile photometric variations and demonstrated that the accuracy of our photometric redshifts is reduced by at most 21%. Application of our star-galaxy classifier reduced the contamination by stars in our catalogues from 60% to 8% at $i'_{\rm AB}$ < 22.5 in our field with the highest stellar density while keeping a complete galaxy sample. Our CFHTLS T0004 photometric redshifts are distributed to the community. Our release includes 592891 ($i'_{\rm AB}$ < 22.5) and 244701 ($i'_{\rm AB}$ < 24) reliable galaxy photometric redshifts in the wide and deep fields, respectively.
Context. Brown dwarfs represent a sizable fraction of the stellar content of our Galaxy and populate the transition between the stellar and planetary mass regime. There is, however, no agreement on ...the processes responsible for their formation. Aims. We have conducted a large survey of the young, nearby cluster IC 348, to uncover its low-mass brown dwarf population and have studied the cluster properties in the substellar regime. Methods. Deep optical and near-IR images taken with MegaCam and WIRCam at the Canada-France-Hawaii Telescope (CFHT) were used to select photometric candidate members. A spectroscopic follow-up of a large fraction of the candidates was conducted to assess their youth and membership. Results. We confirmed spectroscopically 16 new members of the IC 348 cluster, including 13 brown dwarfs, contributing significantly to the substellar census of the cluster, where only 30 brown dwarfs were previously known. Five of the new members have a L0 spectral type, the latest-type objects found to date in this cluster. At 3 Myr, evolutionary models estimate these brown dwarfs to have a mass of ~13 MJup. Combining the new members with previous census of the cluster, we constructed the initial mass function (IMF) complete down to 13 MJup. Conclusions. The IMF of IC 348 is well fitted by a log-normal function and we do not see evidence for variations of the mass function down to planetary masses when compared to other young clusters.
Context. In the last decade, astronomers have found a new type of supernova called superluminous supernovae (SLSNe) due to their high peak luminosity and long light-curves. These hydrogen-free ...explosions (SLSNe-I) can be seen to z ~ 4 and therefore, offer the possibility of probing the distant Universe. Aims. We aim to investigate the possibility of detecting SLSNe-I using ESA’s Euclid satellite, scheduled for launch in 2020. In particular, we study the Euclid Deep Survey (EDS) which will provide a unique combination of area, depth and cadence over the mission. Methods. We estimated the redshift distribution of Euclid SLSNe-I using the latest information on their rates and spectral energy distribution, as well as known Euclid instrument and survey parameters, including the cadence and depth of the EDS. To estimate the uncertainties, we calculated their distribution with two different set-ups, namely optimistic and pessimistic, adopting different star formation densities and rates. We also applied a standardization method to the peak magnitudes to create a simulated Hubble diagram to explore possible cosmological constraints. Results. We show that Euclid should detect approximately 140 high-quality SLSNe-I to z ~ 3.5 over the first five years of the mission (with an additional 70 if we lower our photometric classification criteria). This sample could revolutionize the study of SLSNe-I at z > 1 and open up their use as probes of star-formation rates, galaxy populations, the interstellar and intergalactic medium. In addition, a sample of such SLSNe-I could improve constraints on a time-dependent dark energy equation-of-state, namely w(a), when combined with local SLSNe-I and the expected SN Ia sample from the Dark Energy Survey. Conclusions. We show that Euclid will observe hundreds of SLSNe-I for free. These luminous transients will be in the Euclid data-stream and we should prepare now to identify them as they offer a new probe of the high-redshift Universe for both astrophysics and cosmology.
As part of an all-sky follow-up of the Planck catalogue of Sunyaev-Zeldovich (SZ) cluster candidates detected in the first 14 months of data, we are observing cluster candidates in the southern sky ...in the optical imaging and spectroscopy through an ESO Large Programme. Inspection of ESO New Technology Telescope (NTT) R-and z-band imaging data from our programme has revealed an unusually large and bright arc in the field of PSZ1 G311.65−18.48. We establish the basic photometric and morphological properties of the arc and provide conclusive evidence for the gravitational lensing nature of this object. Guided by the NTT images, we have obtained a long-slit spectrum with IMACS on the Magellan-I Baade Telescope, covering a part of the arc and the brightest cluster galaxy of PSZ1 G311.65−18.48. Our imaging data confirm the presence of a galaxy cluster coinciding (within 0.́6) with the position of the Planck SZ source. The arc is separated by ~30″ from the brightest cluster galaxy, which closely coincides with the center of curvature of the arc. A photometric analysis yields integrated (Vega) magnitudes of (R,z,J,Ks) = (17.82,17.38,16.75,15.43) for the arc, more than one magnitude brighter than any previously known lensed arc at z ~ 2–3. The arc is a vigorously star-forming galaxy at z = 2.369, while the Planck SZ cluster lens is at z = 0.443.Even when allowing for lensing magnifications as high as μ = 100 still leads to the conclusion that the source galaxy is among the intrinsically most luminous normal (i.e., non-AGN) galaxies known at z ~ 2–3.
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