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

Kavli Affiliate: Risa H. Wechsler

| First 5 Authors: Ethan O. Nadler, Vera Gluscevic, Trey Driskell, Risa H. Wechsler, Leonidas A. Moustakas

| Summary:

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 $M_{50}=10^8~M_{mathrm{odot}}$ at the $1sigma$ level; however, a
tail toward low $M_{50}$ prevents a $2sigma$ measurement. In this scenario,
combining hosts with differing bright satellite abundances significantly
reduces uncertainties on $M_{50}$ at the $1sigma$ level, but the $2sigma$
tail toward low $M_{50}$ persists. We project that observations of one (two)
complete satellite populations can constrain warm DM models with
$m_{mathrm{WDM}}approx 10~mathrm{keV}$ ($20~mathrm{keV}$). Subhalo mass
function (SHMF) suppression can be constrained to $approx 70%$, $60%$, and
$50%$ that in CDM at peak virial masses of $10^8$, $10^9$, and
$10^{10}~M_{mathrm{odot}}$, respectively; SHMF enhancement constraints are
weaker ($approx 20$, $4$, 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.

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