NEWLY QUENCHED GALAXIES AS THE CAUSE FOR THE APPARENT EVOLUTION IN AVERAGE SIZE OF THE POPULATION

By C. Carollo, T. Bschorr, A. Renzini, S. Lilly, P. Capak, A. Cibinel, O. Ilbert, M. Onodera, N. Scoville, Ewan Cameron and 3 more. 2013

192 citations recorded by the source corpus.

We use the large COSMOS sample of galaxies to study in an internally self-consistent way the change in the number densities of quenched early-type galaxies (Q-ETGs) of a given size over the redshift interval 0.2 < z < 1 in order to study the claimed size evolution of these galaxies. In a stellar mass bin at 1010.5 < Mgalaxy < 1011 M☉, we see no change in the number density of compact Q-ETGs over this redshift range, while in a higher mass bin at >1011 M☉, where we would expect merging to be more significant, we find a small decrease, by ∼30%. In both mass bins, the increase of the median sizes of Q-ETGs with time is primarily caused by the addition to the size function of larger and more diffuse Q-ETGs. At all masses, compact Q-ETGs become systematically redder toward later epochs, with a (U − V) color difference which is consistent with a passive evolution of their stellar populations, indicating that they are a stable population that does not appreciably evolve in size. We find furthermore, at all epochs, that the larger Q-ETGs (at least in the lower mass bin) have average rest-frame colors that are systematically bluer than those of the more compact Q-ETGs, suggesting that the former are indeed younger than the latter. The idea that new, large, Q-ETGs are responsible for the observed growth in the median size of the population at a given mass is also supported by analysis of the sizes and number of the star-forming galaxies that are expected to be the progenitors of the new Q-ETGs over the same period. In the low mass bin, the new Q-ETGs appear to have ∼30% smaller half-light radii than their star-forming progenitors. This is likely due to the fading of their disks after they cease star formation. Comparison with higher redshifts shows that the median size of newly quenched galaxies roughly scales, at constant mass, as (1 + z)−1. We conclude that the dominant cause of the size evolution seen in the Q-ETG population is that the average sizes and thus stellar densities of individual Q-ETGs roughly scale with the average density of the universe at the time when they were quenched, and that subsequent size changes in individual objects, through merging or other processes, are of secondary importance, especially at masses below 1011 M☉.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/c76bad16add264a2cde46358443c361795bba434

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In Astronomy and Astrophysics

1. L. Hernquist
2. P. Hopkins
3. Volker Springel
4. R. Dav'e
5. R. Somerville
6. A. Dekel
7. T. Naab
8. P. V. van Dokkum

In Instrumentation

1. L. Hernquist
2. P. Hopkins
3. Volker Springel
4. R. Dav'e
5. R. Somerville
6. A. Dekel
7. P. V. van Dokkum
8. C. Conroy

In Statistical and Nonlinear Physics

1. M. Franx
2. M. Kriek
3. P. V. van Dokkum
4. A. Dekel
5. C. Conroy
6. Volker Springel
7. L. Hernquist
8. K. Whitaker

Citations in the corpus

• THE MOSFIRE DEEP EVOLUTION FIELD (MOSDEF) SURVEY: REST-FRAME OPTICAL SPECTROSCOPY FOR ∼1500 H-SELECTED GALAXIES AT 1.37 ≤ z ≤ 3.8 ?> (2014, background): “…grow inside out, but the physical mechanism (e.g., minor mergers, progenitor bias, cold streams and in situ star formation) responsible for the growth is still subject to debate (e.g., van de Sande et al. 2013; Newman et al. 2012a; Carollo et al. 2013; Dutton et al. 2011; van Dokkum et al. 2013).”
• The size evolution of star-forming and quenched galaxies in the IllustrisTNG simulation (2017, background): “…according to which the time evolution of the typical size of quenched galaxies is driven by the appearance of new, large quenched galaxies as a result of the ongoing quenching of (large) star-forming galaxies (Carollo et al. 2013; Cassata et al. 2013; Krogager et al. 2014; Bruce et al. 2014).”
• The MUSE 3D view of the Hubble Deep Field South (2014, background): “…the formation and evolution of the Hubble sequence (e.g. Mortlock et al. 2013; Lee et al. 2013), the change in galaxy sizes with time (e.g. van der Wel et al. 2014; Carollo et al. 2013), and the evolution of the stellar mass function with redshift (e.g. Muzzin et al. 2013; Ilbert et al. 2013).”
• Structural and Star-forming Relations since z ∼ 3: Connecting Compact Star-forming and Quiescent Galaxies (2015, background): “An alternative, or most likely complementary, scenario to explain the fast decline in the normalization of ΣQe is that newly quenched galaxies at lower redshifts have larger sizes and lower density cores (e.g., Poggianti et al. 2013; Carollo et al. 2013).”
• SUBMILLIMETER GALAXIES AS PROGENITORS OF COMPACT QUIESCENT GALAXIES (2014, background): “…2012), but observations suggest that other processes are likely also important, e.g. the continuous addition of increasingly larger newly quenched galaxies to the quenched population with decreasing redshift (e.g. Newman et al. 2012; Carollo et al. 2013; Cassata et al. 2013; Krogager et al. 2013).”
• Evolution of density profiles in high-z galaxies: compaction and quenching inside-out (2015, background): “Furthermore, Re for the more massive galaxies tends to be smaller at every given mass, indicating that galaxies that formed earlier in a denser universe have also on average a higher stellar (effective) density (e.g., Carollo et al. 2013a).”
• The massive end of the luminosity and stellar mass functions: Dependence on the fit to the light profile (2013, result): “In this respect, it is interesting that the z ∼ 1 counts at M∗ ≥ 10 11.5M⊙ of Carollo et al. (2013) are in rather good agreement with our z ∼ 0 (Sersic-based) estimate, strongly limiting merger rates at the high mass end.”
• Compaction and quenching of high-z galaxies in cosmological simulations: blue and red nuggets (2014, background): “While the massive starforming discs of stellar mass∼ 1011M⊙ extend to effective radii of several kpc (Elmegreen et al. 2007; Genzel et al. 2006, 2008), the quenched spheroids of a similar mass have effective radii of order 1 kpc (Carollo et al. 2013; van der Wel et al. 2014).”
• A HIGHLY CONSISTENT FRAMEWORK FOR THE EVOLUTION OF THE STAR-FORMING “MAIN SEQUENCE” FROM z ∼ 0–6 (2014, methodology): “…SFRs relative to other SFR indicators, with SED/UV-corrected SFRs displaying good agreement with other SFR indicators in some cases (D07; Carollo et al. 2013) and up to 0.5 dex scatter/offsets in others (Wuyts et al. 2011b), we will assume here that the scatter is consistent with other…”
• The formation of massive, compact galaxies at z = 2 in the Illustris simulation (2014, background): “It is possible that the observed growth in size of quiescent galaxies with time is due not to the growth of individual galaxies, but to the continual addition of larger galaxies to the quiescent population (progenitor bias, van Dokkum & Franx (2001), see also Carollo et al. (2013)).”
• FORMING COMPACT MASSIVE GALAXIES (2015, result): “Although uncertainties remain (particularly t low redshift; see, e.g., Carollo et al. 2013), it is encouraging that these largely independent samples give similar results. at z> 3: Straatman et al. (2015) recently reported the existence of a sizeable population of compact, massive quiescent…”
• Size evolution of normal and compact galaxies in the EAGLE simulation (2015, background): “A similar conclusion was drawn by Carollo et al. (2013) based on observational measurements.”
• 3D-HST+CANDELS: THE EVOLUTION OF THE GALAXY SIZE–MASS DISTRIBUTION SINCE z = 3 (2014, unknown): “5, while Carollo et al. (2013) claim no evolution at 0 < z < 1.”
• The confinement of star-forming galaxies into a main sequence through episodes of gas compaction, depletion and replenishment (2015, background): “Carollo et al. (2013) argue indeed for a straight mass-dependent quenching process (Peng et al. 2010) of M* disc galaxies from the MS to the quenched population (with dry mergers playing a major role in building the >>M* quenched population, whose properties point at a dissipationless process as…”
• Structure and Kinematics of Early-Type Galaxies from Integral Field Spectroscopy (2016, background): “The advantage of using dynamically-determined masses and density slopes is that it allows one to exclude population gradients (e.g. disk fading) as the only driver of the observed trend (e.g. Carollo et al. 2013).”