Dark Drag Around Sagittarius A*

Abstract

We analyze the effect of Dark Matter (DM) - Standard Model (SM) non-gravitational interactions on the orbital dynamics of celestial bodies near the supermassive black hole Sagittarius A*, where the DM density is generically expected to be high. We outline the conditions under which a DM-SM scattering channel gives rise to a drag force on objects in this region, and show that for sufficiently large cross-sections, this effect can lead to observable orbital decay on timescales as short as a single orbital period. We identify the types of objects most strongly affected by this dark drag and place constraints on specific dark matter distributions and interaction strengths, assuming both elastic and inelastic scattering. For inelastic DM, we find sensitivity to mass splittings that reach the MeV scale. We also demonstrate that a DM-induced drag force could potentially contribute to the observed depletion of red giant branch stars in the innermost region of the Milky Way.