THE MAJORITY OF COMPACT MASSIVE GALAXIES AT z ∼ 2 ARE DISK DOMINATED

By A. van der Wel, Hans-Walter Rix, S. Wuyts, E. McGrath, A. Koekemoer, Eric F. Bell, B. Holden, A. Robaina, D. H. Mcintosh. 2011

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We investigate the stellar structure of massive, quiescent galaxies at z ∼ 2, based on Hubble Space Telescope/WFC3 imaging from the Early Release Science program. Our sample of 14 galaxies has stellar masses of M* > 1010.8 M☉ and photometric redshifts of 1.5 < z < 2.5. In agreement with previous work, their half-light radii are <2 kpc, much smaller than equally massive galaxies in the present-day universe. A significant subset of the sample appears highly flattened in projection, which implies, considering viewing angle statistics, that a significant fraction of the galaxies in our sample have pronounced disks. This is corroborated by two-dimensional surface brightness profile fits. We estimate that 65% ± 15% of the population of massive, quiescent z ∼ 2 galaxies are disk dominated. The median disk scale length is 1.5 kpc, substantially smaller than the disks of equally massive galaxies in the present-day universe. Our results provide strong observational evidence that the much-discussed ultra-dense high-redshift galaxies should generally be thought of as disk-like stellar systems with the majority of stars formed from gas that had time to settle into a disk.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Instrumentation

View Paper: https://www.semanticscholar.org/paper/edbd687f3ab0f933a8a076693ba5fcce846d136c

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Citations in the corpus

WHAT TURNS GALAXIES OFF? THE DIFFERENT MORPHOLOGIES OF STAR-FORMING AND QUIESCENT GALAXIES SINCE z ∼ 2 FROM CANDELS (2011, background): “At z & 1.5, Stockton et al. (2004), McGrath et al. (2008), van Dokkum et al. (2008) and van der Wel et al. (2011) have argued that most quiescent galaxies with masses in excess of 1011M⊙ have prominent stellar disks.”
CANDELS: CONSTRAINING THE AGN–MERGER CONNECTION WITH HOST MORPHOLOGIES AT z ∼ 2 (2011, methodology): “While the connection between spheroid-dominated galaxies and AGNs has been well established at lower redshifts, this is the first such finding at z ∼ 2, where there is evidence that the canonical mass–morphology relationship appears to break down (McGrath et al. 2008; van der Wel et al. 2011).”
THE COSMOLOGICAL SIZE AND VELOCITY DISPERSION EVOLUTION OF MASSIVE EARLY-TYPE GALAXIES (2011, background): “At the end of this phase the observed as well as simulated galaxies are more flattened and disk-like than their low redshift counterparts (van Dokkum et al. 2008; Naab et al. 2009; van der Wel et al. 2011).”
Faint high-redshift AGN in the Chandra deep field south: the evolution of the AGN luminosity function and black hole demography (2011, background): “Disks of z ∼ 2 galaxies are much more compact and much thicker that in today spirals of similar mass (Genzel et al. 2006; van der Wel et al. 2011).”
A LARGE POPULATION OF MASSIVE COMPACT POST-STARBURST GALAXIES AT z > 1: IMPLICATIONS FOR THE SIZE EVOLUTION AND QUENCHING MECHANISM OF QUIESCENT GALAXIES (2011, result): “The observed trends are consistent with a mild evolution towards rounder shapes at lower redshifts, similar to the results by van der Wel et al. (2011).”
GALAXY STRUCTURE AND MODE OF STAR FORMATION IN THE SFR–MASS PLANE FROM z ∼ 2.5 TO z ∼ 0.1 (2011, background): “Observational evidence for high-redshift compact quiescent disks (McGrath et al. 2008; van der Wel et al. 2011) could possibly reflect this, or alternatively may signal other quenching mechanisms at play.”
Structural and Star-forming Relations since z ∼ 3: Connecting Compact Star-forming and Quiescent Galaxies (2015, background): “Interestingly, quiescent galaxies at low-z also seem to have bulge+disk morphologies (McGrath et al. 2008; Bundy et al. 2010; van der Wel et al. 2011), suggesting that quenching takes place among galaxies with similar morphologies.”
Early type galaxies have been the predominant morphological class for massive galaxies since only z~1 (2011, result): “However, some recent works suggests that this could be the case (e.g. van der Wel et al. 2011, Cameron et al. 2011, Weinzirl et al. 2011).”
The Morphologies of Massive Galaxies at 1<z<3 in the CANDELS-UDS Field: Compact Bulges, and the Rise and Fall of Massive Disks (2012, background): “…is particularly interesting in light of the latest morphological studies of high-redshift massive galaxies by Buitrago et al. (2011) and van der Wel et al. (2011) who find that, in contrast to the local population of massive galaxies (which is dominated by bulge morphologies), by z 2 massive…”
How do minor mergers promote inside-out growth of ellipticals, transforming the size, density profile and dark matter fraction? (2012, background): “…n & 5 (Toft et al. 2005; Trujillo 2006; Toft et al. 2007; van Dokkum et al. 2008; van der Wel et al. 2008, 2009; van Dokkum et al. 2010; van der Wel et al. 2011; Kormendy et al. 2009; Carrasco et al. 2010; Weinzirl et al. 2011; Buitrago et al. 2011; Kormendy & Bender 2012; Szomoru et al. 2012).”
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): “…the bulge growth some process must be able to turn off star formation, without destroying the fast-rotating discs that still dominate the local ETGs’ population (Paper II; Paper III) and that dominates the ETGs’ population already from z ∼ 2 (van der Wel et al. 2011; see also van Dokkum 2011).”
CAN MINOR MERGING ACCOUNT FOR THE SIZE GROWTH OF QUIESCENT GALAXIES? NEW RESULTS FROM THE CANDELS SURVEY (2011, unknown): “This is consistent with the majority of these galaxies being bulge-dominated, although some are surely disks (see Kriek et al. 2009a; van der Wel et al. 2011).”
STRUCTURAL PARAMETERS OF GALAXIES IN CANDELS (2012, background): “…and quantity on par with the largest NICMOS data sets in existence (Scoville et al. 2007; Conselice et al. 2011) and produced new insights into the basic structural parameters (e.g., van der Wel et al. 2011; Cassata et al. 2011) and morphologies (e.g., Cameron et al. 2011) of z ∼ 2 galaxies.”
Cuspy No More: How Outflows Affect the Central Dark Matter and Baryon Distribution in Lambda CDM Galaxies (2012, result): “…that in this set of simulations the ‘loading factor’ of the winds, i.e. the amount of baryons removed is typically a few times the current SFR, similar to what is observed in real galaxies over a range of redshifts (Martin 1999; Shapley et al. 2003; Kirby et al. 2011; van der Wel et al. 2011).”
CANDELS: THE PROGENITORS OF COMPACT QUIESCENT GALAXIES AT z ∼ 2 (2012, methodology): “Circularized, effective (half-light) radii, re≡a √ (b/a), and Sèrsic indices were measured from HST/WFC3 H images using GALFIT (Peng et al. 2002) and PSFs created and processed to replicate the conditions of the observed data (van der Wel et al. 2011, and 2012 in prep).”
Wet Disc Contraction to Galactic Blue Nuggets and Quenching to Red Nuggets (2013, background): “Studies of the global shapes of z ∼ 2 red nuggets indicate that they tend to be flattened spheroids, sometimes characterized as “disk-like” or “disk-dominated” (van der Wel et al. 2011; Chang et al. 2013).”
SUPERDENSE GALAXIES AND THE MASS–SIZE RELATION AT LOW REDSHIFT (2012, background): “…regions (see Vulcani et al. 2012 for details). number of S0s.5 Similarly, most of our SDGs have Sersic indices lower than 4, with< n>= 2.8 and a distribution intermediate between disky and spheroidal galaxies, as also highz compact quiescent galaxies do (Wuyts et al. 2010, van der Wel et al. 2011).”
The sizes, masses and specific star formation rates of massive galaxies at 1.3 < z < 1.5: strong evidence in favour of evolution via minor mergers (2012, result): “We note that this is consistent with the recent results of van der Wel et al. (2011), who estimated that 65 ± 15 per cent of passive galaxies at z 2 with stellar masses M ≥ 6 × 1010 M have disc-dominated morphologies, based on HST imaging from the WFC3/IR Early Release Science programme.”
3D-HST+CANDELS: THE EVOLUTION OF THE GALAXY SIZE–MASS DISTRIBUTION SINCE z = 3 (2014, unknown): “…that new early-type galaxies likely form out of the smallest late-type galaxies, the implication is that early-type galaxies are the most dense (and disk-like in structure, e.g., van der Wel et al. 2011; Bruce et al. 2012; Chang et al. 2013) immediately after their star formation is truncated.”