The Evolution of Central Group Galaxies in Hydrodynamical Simulations

Feldmann, Robert; Carollo, C. M.; Mayer, Lucio; Renzini, A.; Lake, George; Quinn, Thomas; Stinson, Greg; Yepes, Gustavo

doi:10.1088/0004-637x/709/1/218

Cited by 106 publications

(149 citation statements)

References 118 publications

(170 reference statements)

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“…The most popular mechanism has been size increase through minor merging (e.g., Hopkins et al 2009;Feldmann et al 2010;Cimatti et al 2012). This latter scenario for the growth of the median size of Q-ETGs requires however about 10 mergers with about 1:10 mass ratios to explain the observed size growth since z ∼ 2 (e.g., van de Sande et al 2013, and references therein).…”

Section: Discussionmentioning

confidence: 99%

Newly Quenched Galaxies as the Cause for the Apparent Evolution in Average Size of the Population

Carollo

Bschorr

Renzini

et al. 2013

ApJ

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283

397

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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 10 10.5 < M galaxy < 10 11 M , we see no change in the number density of compact Q-ETGs over this redshift range, while in a higher mass bin at >10 11 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 10 11 M .

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Section: Discussionmentioning

confidence: 99%

Newly Quenched Galaxies as the Cause for the Apparent Evolution in Average Size of the Population

Carollo

Bschorr

Renzini

et al. 2013

ApJ

Self Cite

283

397

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“…This is true in the SAM, as evidenced by Figure 10. Evidence for the importance of mergers in growing stellar mass comes from studies of cosmological and N-body simulations (Naab et al 2009;Oser et al 2010;Feldmann et al 2010;Lackner et al 2012). Additionally, the tidal tails and streams seen in deep imaging of local massive quiescent galaxies support the picture of mass growth via mergers (van Dokkum 2005;Tal et al 2009;Janowiecki et al 2010).…”

Section: Mass Growth Of Quiescent Galaxiesmentioning

confidence: 94%

Tracing Galaxies Through Cosmic Time With Number Density Selection

Leja

Dokkum

Franx

2013

ApJ

104

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A central challenge in observational studies of galaxy formation is how to associate progenitor galaxies with their descendants at lower redshifts. One promising approach is to link galaxies at fixed number density rather than fixed luminosity or mass. This method is effective if stellar mass rank order is broadly conserved through cosmic time. In this paper, we use the Guo et al. semi-analytical model to analyze under what circumstances this assumption is valid in the context of a cosmological simulation. Specifically, we select progenitor galaxies at a constant number density and compare the stellar mass evolution of their descendants to the evolution at a constant number density. The median stellar mass of the descendants increases by a factor of four (0.6 dex) from z = 3 to z = 0. Constant number density selection reproduces this to within 40% (0.15 dex) over a wide range of number densities. We show that the discrepancy primarily results from scatter in the stellar mass growth rates and merging. After applying simple, observationally based corrections for these processes, the discrepancy is reduced to 12% (0.05 dex). We conclude that number density selection can be used to predict the median descendant mass of high-redshift progenitor galaxies. The main uncertainty in this study is that semi-analytical models do not reproduce the observed mass evolution of galaxies, which makes the quantitative aggregate effects of star formation, merging, and quenching on the rank order of galaxies somewhat uncertain.

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“…This could be potentially important as gas-poor mergers are known to trigger intense size growth of local early type galaxies (e.g. Naab et al 2007;Feldmann et al 2010), whereas accretion of gas (by gas-rich mergers or smooth accretion) is thought not to be able to since their gas shocks radiatively and loses angular momentum, therefore piling up in the central region of the galaxy where it rapidly turns into stars and causes size contraction. The right panel of Fig.…”

Section: Growth Of Galaxy Sizesmentioning

confidence: 99%

“…On the other hand, semi-analytical models and numerical simulations propose that mergers can account for the size increase of local early-type galaxies if they are mostly dry (gas poor) and minor mergers (Boylan-Kolchin et al 2006;Khochfar & Silk 2006;Maller et al 2006;Naab et al , 2007Bournaud et al 2007;De Lucia 2007;Guo & White 2008;Hopkins et al 2009;Nipoti et al 2009;Feldmann et al 2010;Shankar et al 2013;Bédorf & Portegies Zwart 2013). Dry minor mergers explain the loss of compactness of massive ellipticals at z < 2, where they are thought to take over smooth accretion processes in terms of stellar mass increase rates (Oser et al 2010;Lackner et al 2012;Hirschmann et al 2012;Dubois et al 2013;Lee & Yi 2013).…”

Section: Introductionmentioning

confidence: 99%

The rise and fall of stellar across the peak of cosmic star formation history: effects of mergers versus diffuse stellar mass acquisition

Welker

Dubois

Devriendt

et al. 2016

Mon. Not. R. Astron. Soc.

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Building galaxy merger trees from a state-of-the-art cosmological hydrodynamics simulation, Horizon-AGN, we perform a statistical study of how mergers and smooth accretion drive galaxy morphologic properties above z > 1. More specifically, we investigate how stellar densities, effective radii and shape parameters derived from the inertia tensor depend on mergers of different mass ratios. We find strong evidence that smooth accretion tends to flatten small galaxies over cosmic time, leading to the formation of disks. On the other hand, mergers, and not only the major ones, exhibit a propensity to puff up and destroy stellar disks, confirming the origin of elliptical galaxies. We also find that elliptical galaxies are more susceptible to grow in size through mergers than disc galaxies with a size-mass evolution r 0.5 ∝ M 1.2 s instead of r 0.5 ∝ M −0.5 s − M 0.5 depending on the merger mass ratio. The gas content drive the size-mass evolution due to merger with a faster size growth for gas-poor galaxies r 0.5 ∝ M 2 s than for gas-rich galaxies r 0.5 ∝ M s .

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The Evolution of Central Group Galaxies in Hydrodynamical Simulations

Cited by 106 publications

References 118 publications

Newly Quenched Galaxies as the Cause for the Apparent Evolution in Average Size of the Population

Newly Quenched Galaxies as the Cause for the Apparent Evolution in Average Size of the Population

Tracing Galaxies Through Cosmic Time With Number Density Selection

The rise and fall of stellar across the peak of cosmic star formation history: effects of mergers versus diffuse stellar mass acquisition

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