Sweating the small stuff: simulating dwarf galaxies, ultra-faint dwarf galaxies, and their own tiny satellites

By Coral Wheeler, J. Oñorbe, James S. Bullock, M. Boylan-Kolchin, Oliver D. Elbert, S. Garrison-Kimmel, P. Hopkins, D. K. U. O. California, Irvine, Mpia and 4 more. 2015

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We present Feedback in Realistic Environment (FIRE)/GIZMO hydrodynamic zoom-in simulations of isolated dark matter haloes, two each at the mass of classical dwarf galaxies (M_(vir) ≃ 10^(10) M_⊙) and ultra-faint galaxies (M_(vir) ≃ 10^9 M_⊙), and with two feedback implementations. The resulting central galaxies lie on an extrapolated abundance matching relation from M_★ ≃ 10^6 to 10^4 M_⊙ without a break. Every host is filled with subhaloes, many of which form stars. Each of our dwarfs with M_★ ≃ 10^6 M_⊙ has 1–2 well-resolved satellites with M_★ = 3-200 × 10^3 M_⊙. Even our isolated ultra-faint galaxies have star-forming subhaloes. If this is representative, dwarf galaxies throughout the Universe should commonly host tiny satellite galaxies of their own. We combine our results with the Exploring the Local Volume in Simulations (ELVIS) simulations to show that targeting ∼ 50 kpc regions around nearby isolated dwarfs could increase the chances of discovering ultra-faint galaxies by ∼35 per cent compared to random pointings, and specifically identify the region around the Phoenix dwarf galaxy as a good potential target. The well-resolved ultra-faint galaxies in our simulations (M_★ ≃ 3-30 × 10^3 M_⊙) form within M_(peak) ≃ 0.5-3 × 10^9 M_⊙ haloes. Each has a uniformly ancient stellar population ( > 10 Gyr) owing to reionization-related quenching. More massive systems, in contrast, all have late-time star formation. Our results suggest that M_(halo) ≃ 5 × 10^9 M_⊙ is a probable dividing line between haloes hosting reionization ‘fossils’ and those hosting dwarfs that can continue to form stars in isolation after reionization.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/0c7088a4222fd92a36f35e97af981954a57d12db

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Citations in the corpus

Farthest Neighbor: The Distant Milky Way Satellite Eridanus II (2016, background): “…dwarf galaxy located close to, but beyond, the virial radius of Milky Way, Eri II is a key object for studying environmental influences on low-mass galaxies and the quenching of star formation in such systems (Weisz et al. 2014; Wetzel et al. 2015; Wheeler et al. 2015; Fillingham et al. 2016).”
The impact of baryonic physics on the structure of dark matter haloes: the view from the FIRE cosmological simulations (2015, background): “The baryons have little influence on halos withMh 1010M because only a small fraction of available baryons are converted to stars, owing to feedback and the UV background that suppress their star formation after the reionization (Oñorbe et al. 2015; Wheeler et al. 2015).”
Small-Scale Challenges to the ΛCDM Paradigm (2017, background): “Satellites of the LMC and even fainter dwarfs will be attractive targets for ongoing and future observations to test basic predictions of ΛCDM (Wheeler et al. 2015).”
The upper bound on the lowest mass halo (2016, background): “For example, most recently, Shen et al. (2014); Wheeler et al. (2015); Sawala et al. (2016) all used hydrodynamic cosmological zoom-in simulations to claim that below a subhalo virial mass of 109M , dwarf galaxy formation is strongly suppressed due to i) the emergence of the ionising background…”
FIRE in the field: Simulating the threshold of galaxy formation (2016, background): “…including realistic galactic outflows (Muratov et al. 2015), the mass-metallicity relation (Ma et al. 2016), the mass-size relation and age/metallicity gradients (El-Badry et al. 2016), cored dark-matter profiles (Oñorbe et al. 2015; Chan et al. 2015), and stellar kinematics (Wheeler et al. 2015b).”
FIRE-2 simulations: physics versus numerics in galaxy formation (2017, background): “…et al. 2016); observed satellite mass functions, rotation curves/kinematics, and cusp/core structure of dwarfs (Oñorbe et al. 2015; Chan et al. 2015; Wheeler et al. 2015, 2017; Wetzel et al. 2016); abundance gradients (El-Badry et al. 2016; Ma et al. 2017a); neutral hydrogen absorption in the…”
GALAXY PROPERTIES AND UV ESCAPE FRACTIONS DURING THE EPOCH OF REIONIZATION: RESULTS FROM THE RENAISSANCE SIMULATIONS (2016, background): “…Way could be the fossils of this subset of the first galaxies, providing a way to estimate the abundance of dwarf galaxies during the epoch of reionization (Bullock et al. 2000; Salvadori & Ferrara 2009; Bovill & Ricotti 2011; Boylan-Kolchin et al. 2014; Weisz et al. 2014; Wheeler et al. 2015).”
Milky Way Satellite Census. I. The Observational Selection Function for Milky Way Satellites in DES Y3 and Pan-STARRS DR1 (2019, background): “…the demographics of ultra-faint dwarf galaxies offer a unique window into feedback processes in galaxy formation (e.g. Mashchenko et al. 2008; Wheeler et al. 2015, 2019; Munshi et al. 2019; Agertz et al. 2020), reionization and the first stars (e.g., Bullock et al. 2000; Shapiro et al. 2004;…”
EIGHT ULTRA-FAINT GALAXY CANDIDATES DISCOVERED IN YEAR TWO OF THE DARK ENERGY SURVEY (2015, background): “…with the Magellanic system has been discussed for some time (Lynden-Bell 1976; D’Onghia & Lake 2008; Nichols et al. 2011; Sales et al. 2011), and the recent DES results have renewed interest in this topic (Deason et al. 2015; Koposov et al. 2015a; Wheeler et al. 2015; Yozin & Bekki 2015).”
The APOSTLE simulations: solutions to the Local Group's cosmic puzzles (2015, background): “…hydrodynamic simulations which have confirmed the importance of baryonic effects have largely focused on individual dwarf galaxies, ignoring the LG environment (e.g. Stinson et al. 2009; Governato et al. 2010; Sawala et al. 2010, 2011; Nickerson et al. 2011; Shen et al. 2014; Wheeler et al. 2015).”