Prospects for indirect detection of frozen-in dark matter
  We study observational consequences arising from dark matter (DM) of
non-thermal origin, produced by dark freeze-out from a hidden sector heat bath.
We assume this heat bath was populated by feebly-coupled mediator particles,
produced via a Higgs portal interaction with the Standard Model (SM). The dark
sector then attained internal equilibrium with a characteristic temperature
different from the SM photon temperature. We find that even if the coupling
between the DM and the SM sectors is very weak, the scenario allows for
indirect observational signals. We show how the expected strength of these
signals depends on the temperature of the hidden sector at DM freeze-out.
