The K20 survey - I. Disentangling old and dusty star-forming galaxies in the ERO population

By A. Cimatti, E. Daddi, M. Mignoli, L. Pozzetti, A. Renzini, G. Zamorani, T. Broadhurst, A. Fontana, P. Saracco, F. Poli and 5 more. 2001

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We present the results of VLT optical spectroscopy of a complete sample of 78 EROs with R-Ks\geq5 over a field of 52 arcmin^2. About 70% of the 45 EROs with Ks\leq19.2 have been spectroscopically identified with old passively evolving and dusty star-forming galaxies at 0.7<z<1.5. The two classes are about equally populated and for each of them we present and discuss the average spectrum. From the old ERO average spectrum and for Z=Z_{\odot} we derive a minimum age of \sim 3 Gyr, corresponding to a formation redshift of z_f \gtsima 2.4. PLE models with such formation redshifts well reproduce the density of old EROs (consistent with being passively evolving ellipticals), whereas the predictions of the current hierarchical merging models are lower than the observed densities by large factors (up to an order of magnitude). From the average spectrum of the star-forming EROs we estimate a substantial dust extinction with E(B-V) \gtsima 0.5. The star formation rates, corrected for the average reddening, suggest a significant contribution from EROs to the cosmic star-formation density at z \sim 1.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/3cf3c3fc61ff159e260ab3a8fbdd8cd5f092d4a4

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Citations in the corpus

A New Photometric Technique for the Joint Selection of Star-forming and Passive Galaxies at 1.4 ≲ z ≲ 2.5 (2004, methodology): “…et al. 2002; Champan et al. 2003), observing the emission at X-ray or radio wavelengths that are not extincted by dust (e.g., Norman et al. 2004; Haarsma et al. 2000), and selecting very red objects in near-infrared samples that are less affected by dust extinction (Cimatti et al. 2002a, 2003).”
THE SINS SURVEY: MODELING THE DYNAMICS OF z ∼ 2 GALAXIES AND THE HIGH-z TULLY–FISHER RELATION (2009, methodology): “Briefly, the SINS galaxies were selected to be massive star forming galaxies using a variety of complementary techniques in UV through IR wavebands (BX/BM criterion, Adelberger et al. 2004; s-BzK, Daddi et al. 2004b; K magnitude, Cimatti et al. 2002, IRAC flux, Kurk et al. 2006).”
Galaxy Luminosity Functions to z~1 from DEEP2 and COMBO-17: Implications for Red Galaxy Formation (2005, methodology): “…by non-spheroidal galaxies is larger at higher redshifts, amounting to 30% at z ∼ 0.75 (Bell et al. 2004a, Weiner et al. 2005), and may increase beyond that (Cimatti et al. 2002a, 2003; Yan & Thompson 2003; Gilbank et al. 2003; Moustakas et al. 2004).”
A CENSUS OF STAR-FORMING GALAXIES IN THE Z ∼ 9–10 UNIVERSE BASED ON HST+SPITZER OBSERVATIONS OVER 19 CLASH CLUSTERS: THREE CANDIDATE Z ∼ 9–10 GALAXIES AND IMPROVED CONSTRAINTS ON THE STAR FORMATION RATE DENSITY AT Z ∼ 9.2 (2012, methodology): “…z ∼ 1.3-2 galaxy case, we calibrate our priors based on the LF results of Giallongo et al. (2005) for red galaxies using deep near-IR observations available over the HDF-North and HDF-South fields (Williams et al. 1996; Casertano et al. 2000) and the K20 spectroscopic sample (Cimatti et al. 2002).”
RED NUGGETS AT z ∼ 1.5: COMPACT PASSIVE GALAXIES AND THE FORMATION OF THE KORMENDY RELATION (2008, background): “…higher redshifts also, where the paucity of passively evolving galaxies at z > 2 in deep J − K and 3.5 µm selected samples (Kriek et al. 2006; Labbé et al. 2005; Cimatti et al. 2002) shows that the assembly epoch for the red sequence may be decoupled from the epoch of the earliest star formation.”
Spitzer Observations of Massive, Red Galaxies at High Redshift (2005, background): “It is unlikely that the star formation histories of DRGs are consistent with scenarios where all their mass formed in the distant past with subsequent passive evolution (see, e.g., Cimatti et al. 2002b).”
Population Synthesis in the Blue. IV. Accurate Model Predictions for Lick Indices and UBV Colors in Single Stellar Populations (2007, background): “Ongoing surveys based on 8-10 m class telescopes are obtaining large amounts of high-quality spectroscopic data for galaxies at z ∼ 1 (e.g., DEEP survey, Davis et al. 2003; VIRMOS-VLT Deep Survey, Le Févre et al. 2001, K20, Cimatti et al. 2002, Gemini Deep Deep Survey, Abraham et al. 2004).”
The K20 survey. VII. The spectroscopic catalogue: spectral properties and evolution of the galaxy population ⋆, ⋆⋆ (2005, background): “…a number of recent papers which discuss various aspects of galaxy evolution: the spectral and clustering properties of Extremely Red Objects (EROs) (Cimatti et al. 2002a, Paper I; Daddi et al. 2002, Paper II), the comparison between the observed redshift distribution and those predicted by…”
The high‐redshift galaxy population in hierarchical galaxy formation models (2006, methodology): “(Note that the name K20 comes from the survey limit in the Vega system.”
The Galaxy Mass Function up to z=4 in the GOODS-MUSIC sample: into the epoch of formation of massive galaxies ⋆ (2006, unknown): “3 we plot the case for E(B − V) 1.1 (thick dashed line), that is among the highest observed in spectroscopically confirmed EROs (Cimatti et al. 2002).”
Galaxies at z ~ 6: The UV Luminosity Function and Luminosity Density from 506 HUDF, HUDF Parallel ACS Field, and GOODS i-Dropouts (2005, result): “Since B. Vandame et al. (2006, in preparation) noted a similar ∼ 0.1 mag faintward offset relative to the photometry of the K20 survey (Cimatti et al. 2002), we took this offset to be real and offset the J-band zeropoints quoted by B. Vandame et al. (2006, in preparation) by 0.1 mag.”
Mass downsizing and ``top-down'' assembly of early-type galaxies (2006, methodology): “…K-band selected surveys uncovered a substantial populationof old (1-4 Gyr), massive (M > 1011M⊙), passively evolving E/S0 galaxies at 1< z < 2 (e.g. Cimatti et al. 2002a, 2004; McCarthy et al. 2004; Glazebrook et al. 2004: Daddi et al. 2005a; Saracco et al. 2005), and showed that the…”
The environmental dependence of the relations between stellar mass, structure, star formation and nuclear activity in galaxies (2004, background): “There has been considerable recent attention has focused on a population of extremely red objects (EROs) at z > 1 (e.g. Elston et al 1988; Daddi, Cimatti & Renzini 2000; Cimatti et al 2002).”
A Physical Model for the Coevolution of QSOs and Their Spheroidal Hosts (2003, background): “Cimatti et al. (2002a) selected a complete sample of Extremely Red Objects (EROs) ((R−Ks) ≥ 5) with K < 19.2.”
THE DEAD SEQUENCE: A CLEAR BIMODALITY IN GALAXY COLORS FROM z = 0 to z = 2.5 (2009, background): “…3 shows that a red galaxy selection based on a single rest-frame color will contain a significant fraction of dusty-starburst galaxies (∼20% with AV > 1) that would otherwise be much bluer (see also Cimatti et al. 2002; Brammer & van Dokkum 2007; W07; Gallazzi et al. 2009; W09; Wolf et al. 2009).”
A new measurement of the evolving near-infrared galaxy luminosity function out to z≃ 4: a continuing challenge to theoretical models of galaxy formation (2008, methodology): “…with the advent of recent near-infrared surveys, in particular, revealing the presence of a substantial population of old, massive evolved galaxies (Extremely Red Objects, Distant Red Galaxies) at z ∼ > 1.5, which were previously missed by optical surveys (Cimatti et al. 2002; Daddi et al. 2002).”
Age and Metallicity Distribution of the Galactic Bulge from Extensive Optical and Near-IR Stellar Photometry (2002, background): “If such a build up of galaxies was promoted by the hierarchical merging of dark matter halos, it took place at a time and at a rate that no practical rendition of the hierarchical merging paradigm has yet succeded in reproducing (Cimatti et al. 2002 and references therein).”
Near-Infrared Bright Galaxies at z ≃ 2. Entering the Spheroid Formation Epoch? (2003, background): “The agreement between the observed redshift distribution atz> 1.7 and the PLE model described in Cimatti et al. (2002c) is therefore likely to be just chance.”
Stellar Population Diagnostics of Elliptical Galaxy Formation (2006, background): “However, Cimatti et al. (2002a) actually found that out of the 30 EROs with secure redshifts and K < 19.2, only 50% are passively evolving objects and these are distributed in the redshift interval 0.8<∼z<∼1.3, while the other 50% is made by highly-reddened, actively star-forming galaxies.”