Environment and self-regulation in galaxy formation

By D. Thomas, C. Maraston, Kevin Schawinski, M. Sarzi, J. Silk. 2009

425 citations recorded by the source corpus.

The environment is known to affect the formation and evolution of galaxies considerably best visible through the well-known morphology-density relationship. It is less clear, though, whether the environment is equally important at a given galaxy morphology. In this paper we study the effect of environment on the evolution of early-type galaxies as imprinted in the fossil record by analysing the stellar population properti es of 3,360 galaxies morphologically selected by visual inspection from the Sloan Digital Sky Survey in a narrow redshift range (0.05 6 z 6 0.06). The morphological selection algorithm is critical as it d oes not bias against recent star formation. We find that the distribution of ages is bimodal with a strong peak at old ages and a secondary peak at young ages around � 2.5 Gyr containing about 10 per cent of the objects. This is analogue to ’red sequence’ and ’blue cloud’ identified in galaxy populations usually containing both early and late type galaxies. The fraction of the young, rejuvenated galaxies increases with both decreasing galaxy mass and decreasing environmental density up to about 45 per cent, which implies that the impact of environment increases with decreasing galaxy mass. The rejuvenated galaxies have lower �/Fe ratios than the average and most of them show signs of ongoing star formation through their emission line spectra. All objects that host AGN in their centres with out star formation are part of the red sequence population. We confirm and statistically stren gthen earlier results that luminosity weighted ages, metallicities, and �/Fe element ratios of the red sequence population correlate well with velocity dispersion and galaxy mass. Most interestingly, however, these scaling relations are not sensitive to environmental densities and are only driven by galaxy mass. We infer that early-type galaxy formation has undergone a phase transition a few billion years ago aroundz � 0.2. A self-regulated formation phase without environmental dependence has recently been superseded by a rejuvenation phase, in which the environment plays a decisive role possibly through galaxy mergers and interactions.

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Citations in the corpus

• Flux-calibrated stellar population models of Lick absorption-line indices with variable element abundance ratios (2010, methodology): “In a companion paper (Thomas et al. 2010, hereafter Paper II) it is used to derive the element abundance ratios [C/Fe], [N/Fe], [O/Fe], [Mg/Fe], [Ca/Fe], and [Ti/Fe].”
• Toward a Better Understanding of Cosmic Chronometers: A New Measurement of H(z) at z ∼ 0.7 (2021, background): “On the inclusion of lower-mass passive galaxies According to several studies, the evolution of passive galaxies follows a downsizing pattern, with more massive galaxies forming earlier and faster than less massive ones (e.g., Renzini 2006; Pozzetti et al. 2010; Thomas et al. 2010).”
• THE GEMINI CLUSTER ASTROPHYSICS SPECTROSCOPIC SURVEY (GCLASS): THE ROLE OF ENVIRONMENT AND SELF-REGULATION IN GALAXY EVOLUTION AT z ∼ 1 (2011, background): “…2006; Thomas et al. 2005, 2010; Graves et al. 2009), more metal rich (e.g., Tremonti et al. 2004; Gallazzi et al. 2005, 2006; Nelan et al. 2005; Thomas et al. 2005, 2010; Graves et al. 2009) and more frequently having elliptical/S0 morphologies (e.g., Bamford et al. 2009; Nair & Abraham 2010).”
• THE IMPACT OF COLD GAS ACCRETION ABOVE A MASS FLOOR ON GALAXY SCALING RELATIONS (2009, background): “Downsizing and tau models Stellar-population analyses of red galaxies in the local universe show that stars tend to have formed earlier and over a shorter time-span in the most massive ones (e.g. Heavens et al. 2004; Thomas et al. 2005; Jimenez et al. 2007; Thomas et al. 2010).”
• Setting the Stage for Cosmic Chronometers. II. Impact of Stellar Population Synthesis Models Systematics and Full Covariance Matrix (2020, background): “…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 al. 2019; Carnall et al. 2019;…”
• HERSCHEL-ATLAS GALAXY COUNTS AND HIGH-REDSHIFT LUMINOSITY FUNCTIONS: THE FORMATION OF MASSIVE EARLY-TYPE GALAXIES (2011, result): “…dynamical mass−luminosity) have been known for a long time and have been recently confirmed with very large samples, and shown to persist up to substantial redshifts (Renzini 2006; Clemens et al. 2009; Thomas et al. 2010; Rogers et al. 2010; Peebles & Nusser 2010, and references therein).”
• The ATLAS3D project - XIII. Mass and morphology of H I in early-type galaxies as a function of environment (2011, background): “This result fits with the idea that H I is easily stripped from galaxies inside clusters (e.g. Giovanelli & Haynes 1983), and with the fact that recent episodes of star formation occur mostly in ETGs in poor environments (e.g. Thomas et al. 2010).”
• Stellar masses of SDSS-III/BOSS galaxies at z ∼ 0.5 and constraints to galaxy formation models (2012, methodology): “2011; De Lucia & Borgani 2012); the uniformly old stellar ages with little evidence of star formation (Bower et al. 1992, 1998; Thomas et al. 2005; Bernardi et al. 2006), the independence of the stellar population properties of the environment (Peng et al. 2010; Thomas et al. 2010).”
• Inferring the star formation histories of massive quiescent galaxies with bagpipes: evidence for multiple quenching mechanisms (2017, background): “12 of Siudek et al. (2017) that these results are broadly consistent with analyses byMoresco et al. (2010), Jørgensen & Chiboucas (2013) and Onodera et al. (2015), whereas the results of Thomas et al. (2010) and Choi et al. (2014) confirm the continuation of the trends we observe in Fig.”
• Improved constraints on the expansion rate of the Universe up to z ∼ 1.1 from the spectroscopic evolution of cosmic chronometers (2012, methodology): “tribution of the redshifts of formation, we considered the case of a flat distribution (as an extreme case) between zf,min and zf,max and the case of a gaussian distribution (as suggested e.g. by Ref. [15]) with the same mean and dispersion of the flat one. We proceeded as follows: • we built several ”
• OVERVIEW OF THE SDSS-IV MaNGA SURVEY: MAPPING NEARBY GALAXIES AT APACHE POINT OBSERVATORY (2014, background): “Meanwhile, previously quenched systems in low-density environments may experience rejuvenation (e.g., Thomas et al. 2010).”
• THE DATA REDUCTION PIPELINE FOR THE SDSS-IV MaNGA IFU GALAXY SURVEY (2016, background): “…from the Sloan Digital Sky Survey (York et al. 2000; Abazajian et al. 2003) for instance, studies have outlined fundamental relations between stellar mass, metallicity, element abundance ratios, and star formation history (e.g., Kauffmann et al. 2003; Tremonti et al. 2004; Thomas et al. 2010).”
• The ATLAS3D project – IV. The molecular gas content of early-type galaxies (2011, methodology): “Thomas et al. (2010) have used the SDSS spectroscopy to measure luminosity-weighted simple stellar population ages for a sample of low-redshift, morphologically selected early-type galaxies.”
• Galaxy Protoclusters as Drivers of Cosmic Star Formation History in the First 2 Gyr (2017, background): “Massive cluster galaxies, mostly ellipticals and S0s, are believed to have a star-formation history (SFH) shifted to an earlier epoch compared to field galaxies (Thomas et al. 2010), implying that the contribution from cluster progenitors to the CSFRD grows with redshift.”
• How do minor mergers promote inside-out growth of ellipticals, transforming the size, density profile and dark matter fraction? (2012, background): “…of old (z & 2) stellar populations in these galaxies, leaving little room for gas accretion and subsequent star formation (e.g. Searle et al. 1973; Brinchmann & Ellis 2000; Treu et al. 2005; Thomas et al. 2010; van Dokkum et al. 2010; López-Sanjuan et al. 2010; Young 2011; Crocker 2012).”
• Accreting supermassive black holes in the COSMOS field and the connection to their host galaxies (2012, result): “This pattern is similar to the so-called ‘cosmic downsizing’ of star-forming galaxies (Cowie et al. 1996; Menci et al. 2008), also seen in spheroidal galaxies (Cimatti, Daddi & Renzini 2006; Thomas et al. 2010).”
• First results from the IllustrisTNG simulations: a tale of two elements - chemical evolution of magnesium and europium (2017, background): “For comparison, the red lines indicate observations of [Fe/H] values for quiescent galaxy populations, as indicated in the legend (Graves & Schiavon 2008; Thomas et al. 2010; Johansson et al. 2012; Worthey et al. 2013; Conroy et al. 2014).”
• The COSMOS2015 galaxy stellar mass function . Thirteen billion years of stellar mass assembly in ten snapshots (2017, result): “This is consistent with previous studies that indicate that local early-type galaxies with 11 < log(M/M ) < 12 entered into their quiescent phase between z ' 0.8 and 2.5 (Thomas et al. 2010).”
• The current status of galaxy formation (2012, background): “The sudden dominance of major mergers at high galaxy masses is confirmed by trends with stellar mass of the colors, color gradients and elongations of SDSS galaxies (Tremonti et al., 2004; Bernardi et al., 2010, see also van der Wel et al., 2009; Thomas et al., 2010).”