Constraints on dark matter-neutrino scattering from the Milky-Way satellites and subhalo modeling for dark acoustic oscillations

The elastic scattering between dark matter (DM) and radiation can potentially explain small-scale observations that the cold dark matter faces as a challenge, as damping density fluctuations via dark acoustic oscillations in the early universe erases small-scale structure. We study a semi-analytical subhalo model for interacting dark matter with radiation, based on the extended Press-Schechter formalism and subhalos' tidal evolution prescription. We also test the elastic scattering between DM and neutrinos using observations of Milky-Way satellites from the Dark Energy Survey and PanSTARRS1. We conservatively impose strong constraints on the DM-neutrino scattering cross section of sigma(DM-nu,n) proportional to E-nu(n) (n = 0,2,4) at 95% confidence level (CL), sigma(DM-nu,0) < 10(-32) cm(2) (m(DM)/ GeV), sigma(DM-nu,2) < 10(-43) cm(2) (m(DM)/ GeV)(E-nu/E-nu(0))(2) and sigma(DM-nu,4) < 10(-54) cm(2) (m(DM)/GeV)(E-nu/E-nu(0))(4), where E-nu(0) is the neutrino energy and E-nu(0) is the average momentum of relic cosmic neutrinos today, E-nu(0) similar or equal to 6.1 K. By imposing a satellite forming condition, we obtain the strongest upper bounds on the DM-neutrino cross section at 95% CL, sigma(DM-nu,0) < 4 <bold>x</bold> 10(-34) cm(2) (m(DM)/ GeV), sigma(DM-nu,2) < 10(-46) cm(2) (m(DM)/ GeV)(E-nu/E-nu(0))(2) and sigma(DM-nu,4) < 7 <bold>x</bold> 10(-59) cm(2) (m(DM)/GeV)(E-nu/E-nu(0))(4).