A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies. II. Formation of Red Ellipticals

By P. Hopkins, Thomas J. Cox, D. Keres̆, L. Hernquist. 2007

327 citations recorded by the source corpus.

We develop and test a model for the cosmological role of mergers in the formation and quenching of red, early-type galaxies. By combining theoretically well-constrained halo and subhalo mass functions as a function of redshift and environment with empirical halo occupation models, we predict the distribution of mergers as a function of redshift, environment, and physical galaxy properties. Making the simple Ansatz that star formation is quenched after a gas-rich, spheroid-forming major merger, we demonstrate that this naturally predicts the turnover in the efficiency of star formation and baryon fractions in galaxies at ~L* (without any parameters tuned to this value), as well as the observed mass functions and mass density of red galaxies as a function of redshift, the formation times of early-type galaxies as a function of mass, and the fraction of quenched galaxies as a function of galaxy and halo mass, environment, and redshift. Comparing our model to a variety of semianalytic models in which quenching is primarily driven by halo mass considerations or secular/disk instabilities, we demonstrate that our model makes unique and robust qualitative predictions for a number of observables, including the bivariate red fraction as a function of galaxy and halo mass, the density of passive galaxies at high redshifts, the emergence/evolution of the color-morphology-density relations at high redshift, and the fraction of disky/boxy (or cusp/core) spheroids as a function of mass. In each case, the observations favor a model in which some mechanism quenches future star formation after a major merger builds a massive spheroid. Models where quenching is dominated by a halo mass threshold fail to match the behavior of the bivariate red fractions, predict too low a density of passive galaxies at high redshift, and overpredict by an order of magnitude the mass of the transition from disky to boxy ellipticals. Models driven by secular disk instabilities also qualitatively disagree with the bivariate red fractions, fail to predict the observed evolution in the color-density relations, and predict order-of-magnitude incorrect distributions of kinematic types in early-type galaxies. We make specific predictions for how future observations, for example, quantifying the red fraction as a function of galaxy mass, halo mass, environment, or redshift, can break the degeneracies between a number of different assumptions adopted in present galaxy formation models. We discuss a variety of physical possibilities for this quenching and propose a mixed scenario in which traditional quenching in hot, quasi-static massive halos is supplemented by the strong shocks and feedback energy input associated with a major merger (e.g., tidal shocks, starburst-driven winds, and quasar feedback), which temporarily suppress cooling and establish the conditions of a dynamically hot halo in the central regions of the host, even in low-mass halos (below the traditional threshold for accretion shocks).

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/45b4c6e863578214881f29e4b7b532936845b077

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In Astronomy and Astrophysics

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

In Instrumentation

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

Citations in the corpus

• AN ULTRA-DEEP NEAR-INFRARED SPECTRUM OF A COMPACT QUIESCENT GALAXY AT z = 2.2 (2009, background): “The exact mechanism responsible for transforming such active systems into quiescent galaxies is still subject to debate (e.g., Croton et al. 2006; Bower et al. 2006; Naab et al. 2007; Dekel & Birnboim 2008; Hopkins et al. 2008).”
• A general model for the CO–H2 conversion factor in galaxies with applications to the star formation law (2011, background): “…properties of metallicities in mergers (Cox et al. 2006a; Torrey et al. 2011), the broad-band colours of post-starburst galaxies (Snyder et al. 2011), and the structural properties of merging and elliptical galaxies (Hopkins et al. 2008c,d; Hopkins, Cox & Hernquist 2008a; Hopkins et al. 2009).”
• An analytic model for the evolution of the stellar, gas and metal content of galaxies (2011, background): “This may further depend on the merger history of galaxies (Hopkins et al. 2008).”
• The CO-H2 Conversion Factor in Disc Galaxies and Mergers (2011, background): “Similarly, the remnant lies on the fundamental plane (Di Matteo et al. 2005; Robertson et al. 2006; Hopkins et al. 2008a).”
• Galaxies in a simulated ΛCDM universe – II. Observable properties and constraints on feedback (2009, methodology): “Using the halo occupation distribution and the evolution of a type-separated galaxy mass function, (Hopkins et al. 2008a,b) show that such a model, which assumes that star formation stops after the major mergers of gas-rich galaxies, can explain the buildup of the red sequence over time as well as…”
• Evidence of strong quasar feedback in the early Universe (2012, background): “…the bulk of their gas, therefore quenching star formation (Silk & Rees 1998; Granato et al. 2004; Di Matteo et al. 2005; Springel et al. 2005; Croton et al. 2006; Narayanan et al. 2008; Hopkins et al. 2008; Fabian et al. 2009; King 2010; King et al. 2011; Hopkins & Elvis 2010; Zubovas & King 2012).”
• The evolution of massive black holes and their spins in their galactic hosts (2012, background): “…a feedback on the growth of structues, by ejecting gas from the interstellar medium (ISM) and from the intergalactic medium (IGM) (Granato et al. 2004; Lapi et al.2006; Croton et al. 2006; Bower et al. 2006; Hopkins et al. 2008), therefore quenching star formation in low-redshift, massive galaxies.”
• MERGERS AND BULGE FORMATION IN ΛCDM: WHICH MERGERS MATTER? (2009, methodology): “…L∗ ellipticals (in terms of their profile shapes, effective radii and fundamental plane correlations, rotation and higher-order kinematics, isophotal shapes, triaxiality, and other prope ties; see e.g. Naab et al. 2006; Cox et al. 2006a; Jesseit et al. 2007, 2009; Hopkins et al. 2008c,a, 2009c)23.”
• Observational evidence of quasar feedback quenching star formation at high redshift (2011, background): “…are expectedto drive powerful outflows that eventually expel most of the gas in their host galaxies, thereby quenching both star formation and further black hole accretion (Granato et al., 2004; Di Matteo etal., 2005; Menci et al., 2005; Bower et al., 2006; Hopkins et al., 2008; King, 2010, e.g. ).”
• OVERVIEW OF THE SDSS-IV MaNGA SURVEY: MAPPING NEARBY GALAXIES AT APACHE POINT OBSERVATORY (2014, background): “With a large fraction of the gas consumed by the starburst, outflows powered either by winds generated by the accreting black hole or by the starburst itself (e.g., Sharp & BlandHawthorn 2010) can heat the remaining gas and perhaps even expel it from the galaxy altogether (see Hopkins et al. 2008).”
• The physics of galactic winds driven by active galactic nuclei (2012, background): “…the MBH − σ relation (e.g., Silk & Rees 1998; Wyithe & Loeb 2003; Di Matteo et al. 2005) and truncating star formation in massive galaxies (Springel et al. 2005; Hopkins et al. 2008), it is only recently that observations have directly revealed the impact of AGN outflows on galaxy scales.”
• Star formation in galaxy mergers with realistic models of stellar feedback and the interstellar medium (2012, methodology): “…of mergers may be more subtle: inducing resonant disc perturbations (D’Onghia et al. 2009, 2010) and disc heating (Walker, Mihos & Hernquist 1996; Hopkins et al. 2008e; Stewart et al. 2008; Purcell, Kazantzidis & Bullock 2009; Moster et al. 2010), for which the gas response may depend…”
• THE MAJOR AND MINOR GALAXY MERGER RATES AT z < 1.5 (2011, background): “…Laboratory, Pasadena, CA, USA 11 NASA Postdoctoral Fellow of dispersion-dominated spheroids (e.g. Toomre 1977; White & Rees 1978; Kauffmann, White, & Guiderdoni 1993; Mihos & Hernquist 1996; Sanders & Mirabel 1996; Somerville et al. 2001, 2008; di Matteo et al. 2008; Hopkins et al. 2006, 2008).”
• ONGOING AND CO-EVOLVING STAR FORMATION IN zCOSMOS GALAXIES HOSTING ACTIVE GALACTIC NUCLEI (2008, methodology): “…a significant sample of PG quasars (Ho 2005) and type 1 AGN (Kim et al. 2006) from the Sloan Digital Sky Survey (SDSS) may indicate an elevated role for AGN in suppressing star formation (Granato et al. 2004; Springel et al. 2005; Croton et al. 2006; Cavaliere & Menci 2007; Hopkins et al. 2008a).”
• Environment and self-regulation in galaxy formation (2009, methodology): “AGN feedback has been spotted as the most promising solution (Silk & Rees 1998; Binney 2004; Granato et al. 2004; Silk 2005; Miller et al. 2006; Schawinski et al. 2006; Hopkins et al. 2008; Cattaneo et al. 2009; Kormendy et al. 2009; Renzini 2009).”
• Galaxies in a simulated ΛCDM Universe – I. Cold mode and hot cores (2008, background): “Usually one invokes various feed- c© 0000 RAS back processes to shut down star formation in massive galaxies, which enables them to populate the red sequence (see review in Hopkins et al. 2008).”
• DISSIPATION AND EXTRA LIGHT IN GALACTIC NUCLEI. II. “CUSP” ELLIPTICALS (2008, methodology): “…figure is available in the online journal.) the early-type or red galaxy mass functions (Bundy et al. 2006; Borch et al. 2006; Fontana et al. 2006; Hopkins et al. 2006c, 2008b), from direct stellar population synthesis studies (Trager et al. 2000; Thomas et al. 2005; Gallazzi et al. 2005), and by…”
• Quasar feedback: more bang for your buck (2009, background): “These scenarios have been able to explain many quasar observables, including luminosity functions, lifetimes and BH mass functions (Menci et al. 2003; Hopkins et al. 2005b, 2006c, 2008a, 2009; Lapi et al. 2006; Volonteri, Salvaterra & Haardt 2006; Somerville et al. 2008; Tortora et al. 2009).”
• Stellar and Quasar Feedback in Concert: Effects on AGN Accretion, Obscuration, and Outflows (2015, background): “…has been able to explain many quasar observables, including luminosity functions, lifetimes, and ∗ E-mail:phopkins@caltech.edu BH mass functions (Hopkins et al. 2005b, 2006c, 2008b, 2009a; Volonteri et al. 2006; Menci et al. 2003; Somerville et al. 2008; Lapi et al. 2006; Tortora et al. 2009).”
• The baryonic assembly of dark matter haloes (2011, background): “…from https://academic.oup.com/mnras/article-abstract/417/4/2982/1100091 by guest on 29 July 2018 nuclei (AGN), not included here, is probably responsible for suppressing the galaxy mass function in this mass regime (e.g. Croton et al. 2006; Hopkins et al. 2008; Somerville et al. 2008).”