FIRE in the field: Simulating the threshold of galaxy formation

By Alex Fitts, M. Boylan-Kolchin, Oliver D. Elbert, James S. Bullock, P. Hopkins, J. Oñorbe, Andrew Wetzel, Coral Wheeler, C. Faucher-Giguére, D. Keres̆ and 2 more. 2016

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We present a suite of 15 cosmological zoom-in simulations of isolated dark matter haloes, all with masses of M_(halo) ≈ 10^(10) M_⊙ at z = 0, in order to understand the relationship among halo assembly, galaxy formation and feedback's effects on the central density structure in dwarf galaxies. These simulations are part of the Feedback in Realistic Environments (FIRE) project and are performed at extremely high resolution (m_(baryon) = 500 M_⊙, m_(dm) = 2500 M_⊙). The resultant galaxies have stellar masses that are consistent with rough abundance matching estimates, coinciding with the faintest galaxies that can be seen beyond the virial radius of the Milky Way (M_*/M_⊙ ≈ 10^5 − 10^7). This non-negligible spread in stellar mass at z = 0 in haloes within a narrow range of virial masses is strongly correlated with central halo density or maximum circular velocity V_(max), both of which are tightly linked to halo formation time. Much of this dependence of M_* on a second parameter (beyond M_(halo)) is a direct consequence of the M_(halo) ∼ 10^(10) M_⊙ mass scale coinciding with the threshold for strong reionization suppression: the densest, earliest-forming haloes remain above the UV-suppression scale throughout their histories while late-forming systems fall below the UV-suppression scale over longer periods and form fewer stars as a result. In fact, the latest-forming, lowest-concentration halo in our suite fails to form any stars. Haloes that form galaxies with M_⋆ ≳ 2 × 10^6 M_⊙ have reduced central densities relative to dark-matter-only simulations, and the radial extent of the density modifications is well-approximated by the galaxy half-mass radius r_(1/2). Lower-mass galaxies do not modify their host dark matter haloes at the mass scale studied here. This apparent stellar mass threshold of M_⋆ ≈ 2 × 10^6 − 2 × 10^(−4) M_(halo) is broadly consistent with previous work and provides a testable prediction of FIRE feedback models in Λcold dark matter.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/590533010d57ebe039f130f999261179e5ed8bf4

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Citations in the corpus

FIRE-2 simulations: physics versus numerics in galaxy formation (2017, methodology): “…scaling relations of galaxy angular momentum, rotation curves, sizes and the Tully-Fisher relation can be found in El-Badry et al. (2018b,a), while Fitts et al. (2017) and Chan et al. (2018) compare the size, structural properties, and surface brightness distribution functions of dwarfs, and…”
The Local Group on FIRE: dwarf galaxy populations across a suite of hydrodynamic simulations (2018, background): “In principle, however, we may include some systems (particularly in the Local Field) that only recently reached their present-day mass, and which may therefore be expected to remain ‘dark’ (e.g. Fitts et al. 2017).”
Mining for Dark Matter Substructure: Inferring Subhalo Population Properties from Strong Lenses with Machine Learning (2019, background): “Furthermore, suppressed star formation in smaller halos means that there exists a threshold ( (cid:46) 10 8 M ) below which subhalos are expected to be mostly dark and devoid of baryonic activity (Efstathiou 1992; Fitts et al. 2017; Read et al. 2017).”
The hidden giant: discovery of an enormous Galactic dwarf satellite in Gaia DR2 (2018, background): “…by a number of yet-unconstrained physical processes such as cosmic reionization (see e.g. Bose, Deason & Frenk 2018) and stellar feedback (see e.g. Fitts et al. 2017), the total number of bright satellites depends strongly only on the mass of E-mail: gtorrealba@asiaa.sinica.edu.tw the host…”