REPRODUCING THE STELLAR MASS/HALO MASS RELATION IN SIMULATED ΛCDM GALAXIES: THEORY VERSUS OBSERVATIONAL ESTIMATES

By F. Munshi, Fabio Governato, A. Brooks, C. Christensen, S. Shen, Sarah Loebman, B. Moster, Thomas R. Quinn, James Wadsley. 2012

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We examine the present-day total stellar-to-halo mass (SHM) ratio as a function of halo mass for a new sample of simulated field galaxies using fully cosmological, ΛCDM, high-resolution SPH + N-body simulations. These simulations include an explicit treatment of metal line cooling, dust and self-shielding, H2-based star formation (SF), and supernova-driven gas outflows. The 18 simulated halos have masses ranging from a few times 108 to nearly 1012 M☉. At z = 0, our simulated galaxies have a baryon content and morphology typical of field galaxies. Over a stellar mass range of 2.2 × 103–4.5 × 1010 M☉ we find extremely good agreement between the SHM ratio in simulations and the present-day predictions from the statistical abundance matching technique presented in Moster et al. This improvement over past simulations is due to a number systematic factors, each decreasing the SHM ratios: (1) gas outflows that reduce the overall SF efficiency but allow for the formation of a cold gas component; (2) estimating the stellar masses of simulated galaxies using artificial observations and photometric techniques similar to those used in observations; and (3) accounting for a systematic, up to 30% overestimate in total halo masses in DM-only simulations, due to the neglect of baryon loss over cosmic times. Our analysis suggests that stellar mass estimates based on photometric magnitudes can underestimate the contribution of old stellar populations to the total stellar mass, leading to stellar mass errors of up to 50% for individual galaxies. These results highlight that implementing a realistic high density threshold for SF considerably reduces the overall SF efficiency due to more effective feedback. However, we show that in order to reduce the perceived tension between the SF efficiency in galaxy formation models and in real galaxies, it is very important to use proper techniques to compare simulations with observations.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/364306a01d533c3bf8663fb26d936e9ff2883860

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Citations in the corpus

Introducing the Illustris Project: simulating the coevolution of dark and visible matter in the Universe (2014, methodology): “This implies, however, that a proper comparison to hydrodynamical simulations should be based on the relation of halo masses obtained from DM-only simulations and the associated stellar masses as predicted by the corresponding hydrodynamical simulation (Munshi et al. 2013; Sawala et al. 2013).”
NIHAO – IV: core creation and destruction in dark matter density profiles across cosmic time (2015, background): “…shown that baryons are able to alter thedark matter profile and to create substantial cores (up to∼ 1 kpc) in the dark matter distribution (e.g. Governato et al. 2010, Macciò et al. 2012, Martizzi et al. 2013, Munshi et al. 2013, Di Cintio 2014a,b, Trujillo-Gomez et al. 2015, Oñorbe et al. 2015).”
The dependence of dark matter profiles on the stellar-to-halo mass ratio: a prediction for cusps versus cores (2013, methodology): “Governato et al. (2012) measured the inner dark matter slope in a sample of simulated dwarf galaxies, that match well the stellar-to-halo mass relation (Munshi et al. 2013), using a power law density profileρ∝ rα.”
BREATHING FIRE: HOW STELLAR FEEDBACK DRIVES RADIAL MIGRATION, RAPID SIZE FLUCTUATIONS, AND POPULATION GRADIENTS IN LOW-MASS GALAXIES (2015, background): “…despite also having shallow potential wells and high gas fractions, galaxies at this mass form too few stars, in part from significant baryonic mass loss early in their evolution from cosmic reionization and stellar feedback (Munshi et al. 2013; Muratov et al. 2015; Christensen et al. 2015).”