Gas-rich dwarf galaxies as a new probe of dark matter interactions with ordinary matter
Digvijay Wadekar, Glennys R. Farrar
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 dark matter (DM) interacting with gas in the Leo T dwarf galaxy not exceed the ultralow radiative cooling rate of the gas. This enables us to set (i) stronger bounds than all the previous literature on ultralight hidden photon DM for nearly all of the mass range ${10}^{\ensuremath{-}23}\ensuremath{\lesssim}{m}_{\mathrm{DM}}\ensuremath{\lesssim}{10}^{\ensuremath{-}10}\text{ }\text{ }\mathrm{eV}$, (ii) limits on sub-GeV millicharged DM which add to the constraints on the recent EDGES 21 cm absorption anomaly, and (iii) constraints on DM-baryon interactions directly at low relative velocities ${v}_{\mathrm{rel}}\ensuremath{\sim}17\text{ }\text{ }\mathrm{km}/\mathrm{s}$. Our study opens a new direction in using observations of gas-rich dwarf galaxies from previous, current, and upcoming optical and 21 cm surveys to probe physics beyond the standard model.