  We study the possibility of generating baryon asymmetry of the universe from
dark matter (DM) annihilations during non-standard cosmological epochs.
Considering the DM to be of weakly interacting massive particle (WIMP) type,
the generation of baryon asymmetry via leptogenesis route is studied where WIMP
DM annihilation produces a non-zero lepton asymmetry. Adopting a minimal
particle physics model to realise this along with non-zero light neutrino
masses, we consider three different types of non-standard cosmic history
namely, (i) fast expanding universe, (ii) early matter domination and (iii)
scalar-tensor theory of gravity. By solving the appropriate Boltzmann equations
incorporating such non-standard history, we find that the allowed parameter
space consistent with DM relic and observed baryon asymmetry gets enlarged with
the possibility of lower DM mass in some scenarios. While such lighter DM can
face further scrutiny at direct search experiments, the non-standard epochs
offer complementary probes on their own.
