Gas-rich dwarf galaxies as a new probe of dark matter interactions with ordinary matter

Abstract

We use observations of gas-rich dwarf galaxies to derive constraints on dark matter scattering with ordinary matter. We require that heating/cooling due to DM interacting with gas in the Leo T dwarf galaxy not exceed the ultra-low radiative cooling rate of the gas. This enables us to set $(i)$ stronger bounds than all the previous literature on ultra-light hidden photon DM for nearly all of the mass range $10^{-23}\lesssim m_{\mathrm{DM}}\lesssim 10^{-10}$ eV, $(ii)$ limits on sub-GeV millicharged DM which add to the constraints on the recent EDGES 21cm absorption anomaly, and $(iii)$ constraints on DM-baryon interactions directly at low relative velocities $v_{\mathrm{rel}}\sim 17$ km/s. Our study opens a new direction at using observations of gas-rich dwarf galaxies from previous, current and upcoming optical and 21cm surveys to probe physics beyond the standard model.

Comments: 5+10 pages, 4+6 figures. Version appearing in PRD. Title and abstract revised to reflect the primary message of the paper. Minor changes to figures, conclusions unchanged. The code associated with this paper is available at https://github.com/JayWadekar/Gas_rich_dwarfs