The Assembly History of Field Spheroidals: Evolution of Mass-to-Light Ratios and Signatures of Recent Star Formation

By T. Treu, Richard S. Ellis, Ting X. Liao, P. V. van Dokkum, P. Tozzi, A. Coil, J. Newman, M. Cooper, M. Davis. 2005

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We present a comprehensive catalog of high signal-to-noise ratio spectra obtained with DEIMOS on the Keck II telescope for a sample of F850LP < 22.43 (AB) field spheroidal (E+S0 galaxies; 165) and bulge-dominated disk (61) galaxies in the redshift range 0.2 < z < 1.2, selected on the basis of visual morphology from the northern field of the Great Observatories Origins Deep Survey (GOODS-N). We discuss sample selection, photometric properties, and spectral reduction. We derive scale lengths, surface brightnesses, and photometric inhomogeneities from the ACS data and redshifts, stellar velocity dispersions, and [O II] and Hδ equivalent widths from the Keck spectroscopy. Using the published 2 Ms Chandra Deep Field-North X-ray catalog, we identify active galactic nuclei (AGNs) to clarify the origin of emission lines seen in the Keck spectra. Only 2 of 13 [O II]-emitting early-type galaxies are identified as secure AGNs on the basis of their X-ray emission. Contrary to earlier suggestions, we find that most spheroidals containing "blue cores" are not associated with nonthermal nuclear activity. We examine the zero point, tilt, and scatter of the fundamental plane (FP) as a function of redshift and morphological properties, carefully accounting for luminosity-dependent biases via Monte Carlo simulations. The evolution of the overall FP can be represented by a mean change in effective mass-to-light ratio given by ⟨d log(M/LB)/dz⟩ = -0.72 ± 0.04. However, this evolution depends significantly on the dynamical mass, being slower for larger masses as reported in a previous letter. In addition, we separately show that the intrinsic scatter of the FP increases with redshift as d(rms(M/LB))/dz = 0.040 ± 0.015. Although these trends are consistent with single-burst populations that formed at zf > 2 for high-mass spheroidals and zf ~ 1.2 for lower mass systems, a more realistic picture is that most of the stellar mass formed in all systems at z > 2 with subsequent activity continuing to lower redshifts (z < 1.2). The fraction of stellar mass formed at recent times depends strongly on galactic mass, ranging from <1% for masses above 1011.5 M☉ to 20%-40% below 1011 M☉. Independent support for recent activity is provided by spectroscopic ([O II] emission, Hδ) and photometric (blue cores and broadband colors) diagnostics. Via the analysis of a large sample with many independent diagnostics, we are able to reconcile previously disparate interpretations of the assembly history of field spheroidals. We discuss the implications of this measurement for the determination of the evolution of the number density of E+S0 galaxies, suggesting that number density evolution of the morphologically selected population has occurred since z ~ 1.2.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/78eecc590ce2a8ce42a827dc2693e63497527853

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Citations in the corpus

The ATLAS3D project – XX. Mass–size and mass–σ distributions of early-type galaxies: bulge fraction drives kinematics, mass-to-light ratio, molecular gas fraction and stellar initial mass function (2012, background): “…of their scaling parameters (e.g. Bender, Burstein & Faber 1992; Burstein et al. 1997; Kauffmann et al. 2003b; Gallazzi et al. 2006) and from the study of their evolution with redshift (e.g. van Dokkum & Franx 1996; Kelson et al. 1997; van Dokkum et al. 1998; Treu et al. 2005; Franx et al. 2008).”
CAN MINOR MERGING ACCOUNT FOR THE SIZE GROWTH OF QUIESCENT GALAXIES? NEW RESULTS FROM THE CANDELS SURVEY (2011, background): “On the one hand, secondary bursts of star formation are observed in spectroscopic samples of early-type galaxies at z ' 1 (Treu et al. 2005).”
Rates and Properties of Type Ia Supernovae as a Function of Mass and Star Formation in Their Host Galaxies (2006, background): “…in morphologically-selected samples of distant galaxies, a significant fraction of spheroidals have been shown to possess both “blue cores” and weak O ii emission lines in their spectra (Menanteau et al. 2001; Treu et al. 2005), interpreted as a signature of young stars in these galaxies.”
THE INITIAL MASS FUNCTION OF EARLY-TYPE GALAXIES (2010, unknown): “…these quantities correlate with the average epoch of formation of their stellar populations, as well as their average metalliticity, abundance ratios, and gas content (e.g., Treu et al. 2005; Thomas et al. 2005; Gallazzi et al. 2005; Jimenez et al. 2007; Pipino et al. 2009; Graves et al. 2009).”
The Evolving Luminosity Function of Red Galaxies (2006, background): “5) and fundamental plane relations (e.g., van Dokkum & Stanford 2003; Treu et al. 2005) of MV 5 log h 21 red galaxies.”
Red Galaxy Growth and the Halo Occupation Distribution (2008, background): “This correction is comparable to the observed evolution of the fundamental plane (e.g., vanDokkum&Stanford 2003; Treu et al. 2005) and is similar to the luminosity evolution of stellar population models that reproduce the optical colors of red galaxies (e.g., Bell et al. 2004; Brown et al. 2007).”
Compact high-redshift galaxies are the cores of the most massive present-day spheroids (2009, background): “Likewise, there is no change in their kinematics or the fundamental plane relation in clusters or the field (Treu et al. 2005; di Serego Alighieri et al. 2005; van der Wel et al. 2005; van Dokkum & van der Marel 2007).”
Setting the Stage for Cosmic Chronometers. II. Impact of Stellar Population Synthesis Models Systematics and Full Covariance Matrix (2020, background): “…Gyr), and that, having exhausted their gas reservoir in the early stages of their life, they are mostly passively evolving (Cimatti et al. 2004; Treu et al. 2005; Pozzetti et al. 2010; Thomas et al. 2010; Choi et al. 2014; Onodera et al. 2015; Citro et al. 2016; Pacifici et al. 2016; Belli et…”
The SAURON project – XVII. Stellar population analysis of the absorption line strength maps of 48 early-type galaxies (2010, background): “While most massive galaxies have already joined the red sequence at z ∼ 1 (Treu et al. 2005; Bundy et al. 2006; Cimatti et al. 2006), the low mass end of the red sequence seems to be subject to the continued arrival and re-rejuvenation of galaxies up to thepresent day (Treu et al. 2005; Schawinski…”
The SWIRE-VVDS-CFHTLS surveys: stellar mass assembly over the last 10 Gyr. Evidence for a major build up of the red sequence between z = 2 and z = 1 (2007, background): “Evidences of such an effect have been seen in the fundamental plane relation of elliptical galaxies (Treu et al. 2005) as well as in the analysis of spectra of local galaxies (Heavens et al. 2004; Kauffmann et al. 2003) where both analyses show that massive galaxies have formed their stars earlier…”
Kinematic properties of early-type galaxy haloes using planetary nebulae (2008, unknown): “However, observations show that many of the most massive earlytype galaxies were already in place by z ∼ 2 (van Dokkum et al. 2004; Treu et al. 2005), and the evolution of the galaxy luminosity function since redshifts of z ∼ 1 argues against a significant contribution of recent dissipationless dry…”
Photometric Redshifts of Galaxies in COSMOS (2006, methodology): “The template corrections were derived from over 3000 galaxies with spectroscopic redshifts in the Hawaii Hubble Deep Field–North (H-HDF-N; Capak et al. 2004; Cowie et al. 2004; Wirth 2004; Treu et al. 2005; Steidel et al. 2004; Erb et al. 2004).”
COSMOS Morphological Classification with the Zurich Estimator of Structural Types (ZEST) and the Evolution Since z = 1 of the Luminosity Function of Early, Disk, and Irregular Galaxies (2006, result): “This is also suggested by some studies of ellipticals in the local universe (e.g., Carollo et al. 1993; Thomas & Davies 2006) and at high redshifts (e.g., Treu et al. 2005, Daddi et al. 2005).”
Formation of Early-Type Galaxies from Cosmological Initial Conditions (2005, background): “They naturally meet many observational constraints on the evolution of massive spheroidal galaxies (e.g., Treu et al. 2005; Thomas et al. 2005a; van der Wel et al. 2005).”
A Wide-Field Survey of Two z ~ 0.5 Galaxy Clusters: Identifying the Physical Processes Responsible for the Observed Transformation of Spirals into S0s (2007, methodology): “In MS 0451, galaxies were classed by one of us (RSE), and we expect that the typing is accurate to the quoted limits based on previous experience with ACS imaging of similar depth (e.g., Treu et al. 2005).”
Mass downsizing and ``top-down'' assembly of early-type galaxies (2006, methodology): “Instead of relying on stellar population synthesis models, we adopt the passive luminosity dimming derived empirically from the evolution of the Fundamental Plane for cluster ETGs, where ∆log(M/LB) = (−0.46±0.04)z (van Dokkum & Stanford 2003; Treu et al. 2005; di Serego Alighieri et al. 2005).”
Red mergers and the assembly of massive elliptical galaxies: the fundamental plane and its projections (2006, background): “A number of authors have argued that stellar population variations with galaxy mass are responsible for the fundamental plane tilt (e.g. Gerhard et al. 2001; Treu et al. 2005; Cappellari et al. 2006).”