Cosmological Simulations of Milky Way-Sized Galaxies

Abstract

We introduce a new set of eight Milky Way-sized cosmological simulations performed using the AMR code ART + Hydrodynamics in a ΛCDM cosmology. The set of zoom-in simulations covers present-day virial masses that range from 8.3 × 10 11 M ⊙ to 1.56 × 10 12 M ⊙ and is carried out with our simple but effective deterministic star formation (SF) and "explosive" stellar feedback prescriptions. The work is focused on showing the goodness of the simulated set of "field" Milky Way-sized galaxies. To this end, we compare some of the predicted physical quantities with the corresponding observed ones. Our results are as follows. (a) In agreement with some previous works, we found circular velocity curves that are flat or slightly peaked. (b) All simulated galaxies with a significant disk component are consistent with the observed Tully-Fisher, radius-mass, and cold gas-stellar mass correlations of latetype galaxies. (c) The disk-dominated galaxies have stellar specific angular momenta in agreement with those of late-type galaxies, with values around 10 3 km/s/kpc. (d) The SF rates at z = 0 of all runs but one are comparable to those estimated for the star-forming galaxies. (e) The two most spheroid-dominated galaxies formed in halos with late active merger histories and late bursts of SF, but the other run that ends also as dominated by an spheroid, never had major mergers. (f) The simulated galaxies lie in the semi-empirical stellar-to-halo mass correlation of local central galaxies, and those that end up as disk dominated, evolve mostly along the low-mass branch of this correlation. Moreover, the baryonic and stellar mass growth histories of these galaxies are proportional to their halo mass growth histories since the last 6.5-10 Gyr. (g) Within the virial radii of the simulations, ≈ 25 − 50% of the baryons are missed; the amount of gas in the halo is similar to the one in stars in the galaxy, and most of this gas is in the warm-hot phase. (h) The z ∼ 0 vertical gas velocity dispersion profiles, σ z (r), are nearly flat and can be mostly explained by the kinetic energy injected by stars. The average values of σ z increase at higher redshifts, following roughly the shape of the SF history.

Optical integral field spectroscopy observations applied to simulated galaxies: testing the fossil record method

“…A stellar particle of mass m * = SFmg is placed in a grid cell every time the above conditions are simultaneously satisfied, where mg is the gas mass in the cell and SF is a parameter set to 0.65. This value and those of the other subgrid parameters were found in Colín et al (2016, see also Avila-Reese et al 2011) to be optimal for the given minimal spatial resolution (109 h −1 pc) and the integration time steps attained in their simulations.…”

“…The aim of this paper is to explore how reliable are the fossil record method inferences of the radial/global MGHs and the age gradients, taking into account the several limiting aspects mentioned above. For this aim, we will use state-of-the-art N-body + Hydrodynamics simulations of two galaxies taken from the suite of zoom-in cosmological simulations presented in Colín et al (2016). The MW-sized galaxies from this set present realistic properties and span a morphological range from disk-to spheroid-dominated ones.…”

“…For the main goal of this paper, we need well-resolved simulated galaxies. This is the case of the suite of eight zoomin cosmological simulations presented in Colín et al (2016) and Avila-Reese et al (2018). The simulations correspond to Milky Way-sized galaxies chosen to be in relatively isolated halos today.…”

Gas accretion and galactic fountain flows in the Auriga cosmological simulations: angular momentum and metal redistribution

“…Only recently, however, have numerical simulations successfully managed to produce star-forming spiral disc galaxies with prominent, rotationally supported disc components that reproduce numerous scaling relations (e.g. Brook et al 2012b;Aumer et al 2013;Marinacci et al 2014;Wang et al 2015;Colín et al 2016;Grand et al 2017). The general picture now emerging from simulations is that the formation of discs is promoted because energetic feedback expels low angular momentum gas from the central regions that later re-accretes onto the galaxy, providing fuel for late-time star formation from gas with, on average, high angular momentum (Brook et al 2011(Brook et al , 2012aÜbler et al 2014;Teklu et al 2015;Zavala et al 2016;Christensen et al 2016;Agertz & Kravtsov 2016;DeFelippis et al 2017) that should be well-aligned with the disc (e.g.…”

Identifying Kinematic Structures in Simulated Galaxies Using Unsupervised Machine Learning

“…Numerical simulations are powerful tools for studying the formation and evolution of galaxy structures. In recent years, significant progress has been made in modelling star formation and stellar feedback, leading to increasingly realistic galaxies with reasonable bulgeto-disk ratios (Agertz et al 2011;Guedes et al 2011;Aumer et al 2013;Stinson et al 2013;Marinacci et al 2014;Roškar et al 2014;Murante et al 2015;Colín et al 2016;Grand et al 2017). The increase of simulation resolution has enabled us to generate galaxies with multiple structures that go much beyond the basic bulge+disk system, including vertical structures of disks (Brook et al 2012;Ma et al 2017;Navarro et al 2018;Obreja et al 2018b), stellar halos (Cooper et al 2010;Tissera et al 2013;Pillepich et al 2014;Elias et al 2018;Monachesi et al 2019), pseudo bulges (Okamoto 2013;Guedes et al 2013), and bars (Algorry et al 2017;Peschken & Lokas 2019).…”