Local Group star formation in warm and self-interacting dark matter
  cosmologies
  The nature of the dark matter can affect the collapse time of dark matter
haloes, and can therefore be imprinted in observables such as the stellar
population ages and star formation histories of dwarf galaxies. In this paper
we use high resolution hydrodynamical simulations of Local Group-analogue (LG)
volumes in cold dark matter (CDM), sterile neutrino warm dark matter (WDM) and
self-interacting dark matter (SIDM) models with the EAGLE galaxy formation code
to study how galaxy formation times change with dark matter model. We are able
to identify the same haloes in different simulations, since they share the same
initial density field phases. We find that the stellar mass of galaxies depends
systematically on resolution, and can differ by as much as a factor of two in
haloes of a given dark matter mass. The evolution of the stellar populations in
SIDM is largely identical to that of CDM, but in WDM early star formation is
instead suppressed. The time at which LG haloes can begin to form stars through
atomic cooling is delayed by $\sim$200~Myr in WDM models compared to CDM. It
will be necessary to measure stellar ages of old populations to a precision of
better than 100~Myr, and to address degeneracies with the redshift of
reionization -- and potentially other baryonic processes -- in order to use
these observables to distinguish between dark matter models.
