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We study galaxy formation in sterile neutrino dark matter models that differ signifi- cantly from both cold and from `warm thermal relic models. We use the EAGLE code to carry out hydrodynamic simulations of the evolution of pairs of galaxies chosen to resemble the Local Group, as part of the APOSTLE simulations project. We compare cold dark matter (CDM) with two sterile neutrino models with 7 keV mass: one, the warmest among all models of this mass (LA120) and the other, a relatively cold case (LA10). We show that the lower concentration of sterile neutrino subhalos compared to their CDM counterparts makes the inferred inner dark matter content of galaxies like Fornax (or Magellanic Clouds) less of an outlier in the sterile neutrino cosmologies. In terms of the galaxy number counts the LA10 simulations are indistinguishable from CDM when one takes into account halo-to-halo (or `simulation-to-simulation) scatter. In order for the LA120 model to match the number of Local Group dwarf galaxies, a higher fraction of low mass haloes is required to form galaxies than is predicted by the EAGLE simulations. As the census of the Local Group galaxies nears completion, this population may provide a strong discriminant between cold and warm dark matter models.
We show that the canonical oscillation-based (non-resonant) production of sterile neutrino dark matter is inconsistent at $>99$% confidence with observations of galaxies in the Local Group. We set lower limits on the non-resonant sterile neutrino mas
Low mass galaxies are expected to be dark matter dominated even within their centrals. Recently two observations reported two dwarf galaxies in group environment with very little dark matter in their centrals. We explore the population and origins of
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 h
The anomalous 3.55 keV X-ray line recently detected towards a number of massive dark matter objects may be interpreted as the radiative decays of 7.1 keV mass sterile neutrino dark matter. Depending on its parameters, the sterile neutrino can range f
We searched for isolated dark matter deprived galaxies within several state-of-the-art hydrodynamical simulations: Illustris, IllustrisTNG, EAGLE, and Horizon-AGN and found a handful of promising objects in all except Horizon-AGN. While our initial g