Galaxy Formation: Cold Dark Matter, Feedback, and the Hubble Sequence

By J. Sommer-Larsen, M. Götz, L. Portinari. 2002

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TreeSPH simulations of galaxy formation in a standard Λ cold dark matter cosmology, including star formation and the effects of energetic stellar feedback processes and of a metagalactic UV field, have been performed, resulting in a mix of realistic disk, lenticular, and elliptical galaxies at redshift z = 0. The disk galaxies are deficient in angular momentum by only about a factor of 2 compared with observed disk galaxies for simulations with fairly strong starbursts in early, protogalactic clouds, leading to "blow-away" of the remaining gas in the clouds. In this respect the present scenario is hence doing almost as well as the warm dark matter (WDM) scenarios discussed by Sommer-Larsen & Dolgov. The surface density profiles of the stellar disks are approximately exponential, and those of the bulges range from exponential to r1/4, as observed. The bulge-to-disk ratios of the disk galaxies are consistent with observations, as are their integrated B-V colors, which have been calculated using stellar population synthesis techniques. Furthermore, the observed I-band Tully-Fisher relation can be matched, provided that the stellar mass-to-light ratio of disk galaxies is M/LI ~ 0.8, similar to what was found by Sommer-Larsen & Dolgov from their WDM simulations and in fair agreement with several recent observational determinations of M/LI for disk galaxies. The elliptical and lenticular galaxies have approximately r1/4 stellar surface density profiles, are dominated by nondisklike kinematics, and are flattened as a result of nonisotropic stellar velocity distributions, again consistent with observations. Hot halo gas is predicted to cool out and be accreted onto the Galactic disk at a rate of 0.5-1 M☉ yr-1 at z = 0, consistent with upper limits deduced from Far Ultraviolet Spectroscopic Explorer observations of O VI. We have analyzed in detail the formation history of two disk galaxies with circular speeds comparable to that of the Milky Way and find gas accretion rates, and hence bolometric X-ray luminosities of the halos, 6-7 times larger at z ~ 1 than at z = 0 for these disk galaxies. More generally, it is found that gas infall rates onto these disks are nearly exponentially declining with time, both for the total disk and for the "solar cylinder." This theoretical result hence supports the exponentially declining gas infall approximation often used in chemical evolution models. The infall timescales deduced are ~5-6 Gyr, comparable to what is adopted in current chemical evolution models to solve the "G dwarf problem." The disk of one of the two galaxies forms "inside-out," the other "outside-in," but in both cases the mean ages of the stars in the outskirts of the disks are ≳6-8 Gyr, fairly consistent with the findings of Ferguson & Johnson for the disk of M31. The amount of hot gas in disk galaxy halos is consistent with observational upper limits. The globular cluster M53 and the LMC are "inserted" in the halos of the two Milky Way-like disk galaxies, and dispersion measures to these objects are calculated. The results are consistent with upper limits from observed dispersion measures to pulsars in these systems. Finally, the results of the simulations indicate that the observed peak in the cosmic star formation rate at redshift z ~ 2 can be reproduced. Depending on the star formation and feedback scenarios, one predicts either a cosmic star formation rate that decreases monotonically with redshift beyond these redshifts or a second peak at z ~ 6-8, corresponding to the putative Population III and interestingly similar to recent estimates of the redshift at which the universe was reionized. These various scenarios should hence be observationally constrainable with upcoming instruments such as the James Webb Space Telescope and the Atacama Large Millimeter Array.

Subfields: Astronomy and Astrophysics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/ae511e2733c550890c295f35c37d9501c61c3bd2

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Citations in the corpus

Gaseous Galaxy Halos (2012, background): “…of the long-lived stars in the Galactic disk indicate the vast majority of the incoming fuel should be low metallicity, and therefore feedback material cannot be the dominant fuel at all redshifts (Chiappini et al., 2001; Larson, 1972; Fenner & Gibson, 2003; Sommer-Larsen et al., 2003).”
Star formation and feedback in smoothed particle hydrodynamic simulations – I. Isolated galaxies (2006, background): “Thacker & Couchman (2001); Sommer-Larsen et al. (2003); Governato et al. (2006) used this recipe in cosmological simulations of forming galaxies.”
Toward First-Principle Simulations of Galaxy Formation: I. How Should We Choose Star-Formation Criteria in High-Resolution Simulations of Disk Galaxies? (2008, background): “…& Mueller 1994; Mihos & Hernquist 1994; Katz et al. 1996; Yepes et al. 1997; Thacker & Couchman 2001; Abadi et al. 2003; Kawata & Gibson 2003; Sommer-Larsen et al. 2003; Springel & Hernquist 2003; Robertson et al. 2004; Saitoh & Wada 2004; Okamoto et al. 2005; Stinson et al. 2006;…”
The properties of satellite galaxies in simulations of galaxy formation (2009, background): “There is a long history of attempts to simulate the formation of spiral galaxies from ΛCDM initial conditions (e.g. Abadi et al. 2003a; Sommer-Larsen et al. 2003; Governato et al. 2004; Robertson et al. 2004; Okamoto et al. 2005; Governato et al. 2007; Ceverino & Klypin 2009; Scannapieco et al.…”
A Revised Model for the Formation of Disk Galaxies: Low Spin and Dark Halo Expansion (2006, background): “…a generic problem that has been identified in numerical simulations (Elizondo et al. 1999; Navarro & Steinmetz 2000, Eke, Navarro & Steinmetz 2001; Sommer-Larsen et al. 2003), in semi-analytic models (e.g., Mo & Mao 2000; van den Bosch 2000, Firmani & Avila- Reese 2000; Cole et al. 2000; Benson…”
The Secular Evolution of Disk Structural Parameters (2005, unknown): “2004; Abadi et al. 2003; Sommer-Larsen et al. 2003).”
A model for cosmological simulations of galaxy formation physics: multi-epoch validation (2013, background): “…2012c) or suppression of radiative cooling after injection of thermal energy (e.g., Gerritsen & Icke 1997; Thacker & Couchman 2000; Kawata & Gibson 2003; Sommer-Larsen et al. 2003; Brook et al. 2004; Stinson et al. 2006; Piontek & Steinmetz 2011; Dalla Vecchia & Schaye 2012; Stinson et al. 2013).”
THE ROLE OF STELLAR FEEDBACK IN THE FORMATION OF GALAXIES (2007, methodology): “The most common method is to artificially stop cooling when the stellar energy is deposited (Gerritsen & Icke 1997; Thacker & Couchman 2000; Sommer-Larsen et al. 2003; Kereš et al. 2005; Governato et al. 2007) This approach prolongs the adiabatic phase of SN explosion (the Sedov solution) to about…”
THE SINS SURVEY: MODELING THE DYNAMICS OF z ∼ 2 GALAXIES AND THE HIGH-z TULLY–FISHER RELATION (2009, methodology): “…disks in some cases (Robertson et al. 2006, Robertson & Bullock 2008), on average a more continuous and steady mass accretion mechanism, such as through cold flows along cosmic web filaments (Keres et al. 2005, Dekel & Birnboim 2006, Dekel et al. 2008, Sommer-Larsen et al. 2003), could be invoked.”
PLATO as it is: a legacy mission for Galactic archaeology (2017, unknown): “…now, was established, as suggested by many theoretical models (e.g., Abadi et al. 2003; Bird et al. 2013; Bournaud et al. 2009; Brook et al. 2004; Gibson et al. 2009; Guedes et al. 2013; Jones & Wyse 1983; Kawata & Chiappini 2016; Noguchi 1998; Sommer-Larsen et al. 2003; Steinmetz & Mueller 1994).”
MERGERS IN ΛCDM: UNCERTAINTIES IN THEORETICAL PREDICTIONS AND INTERPRETATIONS OF THE MERGER RATE (2010, methodology): “As a consequence the most successful versions of such models have considered high-resolution “zoom-in” models of individual galaxies in formation, with extensive feedback prescriptions (e.g. Sommer-Larsen et al. 2003; Governato et al. 2007; Okamoto et al. 2005; Scannapieco et al. 2008).”