Constraining the primordial curvature perturbation using dark matter substructure
Shin’ichiro Ando, Nagisa Hiroshima, Koji Ishiwata
Abstract
We investigate the primordial curvature perturbation by the observation of the dark matter substructure. Assuming a bump in the spectrum of the curvature perturbation in the wave number of $k>1\text{ }\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$, we track the evolution of the host halo and subhalos in a semianalytic way. Taking into account possible uncertainties in the evaluation of the tidal stripping effect on the subhalo growth, we find a new robust bound on the curvature perturbation with a bump from the number of observed dwarf spheroidal galaxies in our Galaxy and the observations of the stellar stream. The upper limit on the amplitude of the bump is $\mathcal{O}({10}^{\ensuremath{-}7})$ for $k\ensuremath{\sim}{10}^{3}\text{ }\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$. Furthermore, we find the boost factor, which is crucial for the indirect detection of dark matter signals, is up to $\mathcal{O}({10}^{4})$ due to the bump that is allowed in the current observational bounds.