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 σ _DM-ν,n ∝ Eⁿ_ν (n = 0,2,4) at 95% confidence level (CL), σ _DM-ν,0 < 10^-32 cm² (m _DM/ GeV), σ _DM-ν,2 < 10^-43 cm² (m _DM/ GeV)(E_ν /E_ν⁰)² and σ _DM-ν,4 < 10^-54 cm² (m _DM /GeV)(E_ν /E_ν⁰)⁴, where E_ν⁰ is the neutrino energy and E_ν⁰ is the average momentum of relic cosmic neutrinos today, E_ν⁰ ≃ 6.1 K.