Soft Scattering Evaporation of Dark Matter Subhalos by Inner Galactic
  Gases
  The large gap between a galactic dark matter subhalo's velocity and its own
gravitational binding velocity creates the situation that dark matter
soft-scattering on baryons to evaporate the subhalo, if kinetic energy transfer
is efficient by low momentum exchange. Small subhalos can evaporate before dark
matter thermalize with baryons due to the low binding velocity. In case dark
matter acquires an electromagnetic dipole moment, the survival of low-mass
subhalos requires stringent limits on the photon-mediated soft scattering. We
calculate the subhalo evaporation rate via soft collision by ionization gas and
accelerated cosmic rays, and show the stability of subhalos lighter than
$10^{-5}M_{\odot}$ in the gaseous inner galactic region is sensitive to dark
matter's effective electric and magnetic dipole moments below current direct
detection limits.
