Forecasts for Galaxy Formation and Dark Matter Constraints from Dwarf Galaxy Surveys

Abstract

The abundance of faint dwarf galaxies is determined by the underlying population of low-mass dark matter (DM) halos and the efficiency of galaxy formation in these systems. Here, we quantify potential galaxy formation and DM constraints from future dwarf satellite galaxy surveys. We generate satellite populations using a suite of Milky Way (MW)–mass cosmological zoom-in simulations and an empirical galaxy–halo connection model, and assess sensitivity to galaxy formation and DM signals when marginalizing over galaxy–halo connection uncertainties. We find that a survey of all satellites around one MW-mass host can constrain a galaxy formation cutoff at peak virial masses of M 50 = 10 8 M ⊙ at the 1σ level; however, a tail toward low M 50 prevents a 2σ measurement. In this scenario, combining hosts with differing bright satellite abundances significantly reduces uncertainties on M 50 at the 1σ level, but the 2σ tail toward low M 50 persists. We project that observations of one (two) complete satellite populations can constrain warm DM models with m WDM ≈ 10 keV (20 keV). Subhalo mass function (SHMF) suppression can be constrained to ≈70%, 60%, and 50% that in cold dark matter (CDM) at peak virial masses of 108, 109, and 1010 M ⊙, respectively; SHMF enhancement constraints are weaker (≈20, 4, and 2 times that in CDM, respectively) due to galaxy–halo connection degeneracies. These results motivate searches for faint dwarf galaxies beyond the MW and indicate that ongoing missions like Euclid and upcoming facilities including the Vera C. Rubin Observatory and Nancy Grace Roman Space Telescope will probe new galaxy formation and DM physics.

Milky Way-est: Cosmological Zoom-in Simulations with Large Magellanic Cloud and Gaia–Sausage–Enceladus Analogs

“…Milky Way-est simulations resolve subhalos down to present-day masses of ≈10 8 M e , near the threshold of galaxy formation (Benitez-Llambay & Frenk 2020;Nadler et al 2020); detailed comparisons between Milky Way-est and Symphony MW will therefore help contextualize upcoming observations of the MW satellite population, which probe galaxy formation and dark matter physics (Nadler et al 2024). More generally, Milky Way-est provides a realistic setting for testing empirical galaxy-halo connection models (e.g., Nadler et al 2019;Wang et al 2021), conducting zoom-in simulations of galaxy formation (e.g., Wetzel et al 2016;Font et al 2020;Applebaum et al 2021), and exploring physics beyond the cold-dark-matter paradigm (e.g., Nadler et al 2021bNadler et al , 2021aMau et al 2022;Yang et al 2023) in a setting that facilitates accurate predictions for near-field cosmology.…”