Star formation histories of dwarf galaxies in the FIRE simulations: dependence on mass and Local Group environment

Abstract

We study star formation histories (SFHs) of 500 dwarf galaxies (stellar mass M * = 10 5 − 10 9 M ) from FIRE-2 cosmological zoom-in simulations. We compare dwarfs around individual Milky Way (MW)-mass galaxies, dwarfs in Local Group (LG)-like environments, and true field (i.e. isolated) dwarf galaxies. We reproduce observed trends wherein highermass dwarfs quench later (if at all), regardless of environment. We also identify differences between the environments, both in terms of "satellite vs. central" and "LG vs. individual MW vs. isolated dwarf central." Around the individual MW-mass hosts, we recover the result expected from environmental quenching: central galaxies in the "near field" have more extended SFHs than their satellite counterparts, with the former more closely resemble isolated ("true field") dwarfs (though near-field centrals are still somewhat earlier forming). However, this difference is muted in the LG-like environments, where both near-field centrals and satellites have similar SFHs, which resemble satellites of single MW-mass hosts. This distinction is strongest for M * = 10 6 -10 7 M but exists at other masses. Our results suggest that the paired halo nature of the LG may regulate star formation in dwarf galaxies even beyond the virial radii of the MW and Andromeda. Caution is needed when comparing zoom-in simulations targeting isolated dwarf galaxies against observed dwarf galaxies in the LG.Observations have begun to provide detailed constraints on the star formation histories of a large fraction of the dwarf galaxies in the Local Group (LG; defined as the cosmological volume

Linking globular cluster formation at low and high redshift through the age–metallicity relation in E-MOSAICS

“…Here, we see that there is no significant offset between the AMR of the satellites and centrals. This result is in agreement with findings by Garrison-Kimmel et al (2019), who studied the SFHs of dwarf galaxies with a range of masses in the Feedback In Realistic Environments (FIRE)-2 simulations (Hopkins et al 2018). Specifically, these authors compared the SFHs of satellite galaxies and centrals, and found that for L/SMC-mass galaxies (see Section 4), the SFH of centrals near MW-mass galaxies were most alike the SFH of the LMC and SMC galaxies.…”

The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. IV. The Star Formation History of Andromeda VII Derived from Long-period Variable Stars

“…The τ 90 of these galaxies were found from 7.4 to 5.2 Gyr ago ( ( ) = t log yr 9.87-9.72) by Weisz et al (2015), and the quenching time of And VII, with the largest mass, is later than most if not all of them. Our results confirm the observed relation that lower-mass dwarfs typically cease stellar mass assembly earlier than higher-mass galaxies (Weisz et al 2015;Garrison-Kimmel et al 2019). We note that these five galaxies are located within the M31 virial radius, where the quenching time is thus essentially independent of the current proximity to M31 (Weisz et al 2015).…”

A Scenario for Ultradiffuse Satellite Galaxies with Low Velocity Dispersions: The Case of [KKS 2000]04

“…White & Frenk 1991), assume that a significant gas fraction has already cooled and settled well inside the virial radius. In accordance with observations (Behroozi et al 2013) and simulations of galaxy formation (Garrison-Kimmel et al 2019), we also assume that at this stage only a fraction < ∼ 0.2 of the final stellar mass has formed 2 . As the (gas rich) satellite orbits into the parent halo, it begins to lose matter from its outer parts by the tidal gravitational forces of the parent halo.…”