Gravitational scattering of the sterile neutrino halo dark matter

Abstract

A recent study shows that gravitational scattering of dark matter, in the form of massive objects with mass $m \sim 10^3-10^4M_{\odot}$, could provide a possible solution to alleviate the small-scale structure problems of cold dark matter. The scattering cross section is velocity-dependent so that this scenario can explain why self-interaction of dark matter is significant in dwarf galaxies, but not in massive galaxies and galaxy clusters. In this Letter, we show that this kind of dark massive objects could be made of sterile neutrinos with a possible rest mass range $m_{\nu} \sim 7.6$ keV $-$ 71 MeV. This mass range generally satisfies most of the current observational constraints. The entire structure of the sterile neutrino halos can be simply predicted from standard physics.