Constraining the primordial curvature perturbation using dark matter substructure

TL;DR

This paper constrains the primordial curvature perturbation by analyzing dark matter substructure, deriving bounds from dwarf galaxies and stellar streams, and assessing implications for dark matter detection.

Contribution

It introduces a new robust bound on the curvature perturbation bump using observational data and accounts for uncertainties in subhalo tidal stripping effects.

Findings

Upper limit on bump amplitude: O(10^{-7}) at k~10^3 Mpc^{-1}

Boost factor for dark matter detection up to O(10^4)

Constraints derived from dwarf spheroidal galaxies and stellar streams

Abstract

We investigate the primordial curvature perturbation by the observation of dark matter substructure. Assuming a bump in the spectrum of the curvature perturbation in the wavenumber of k>1 Mpc^{-1}, we track the evolution of the host halo and subhalos in a semi-analytic 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 O(10^{-7}) for k~10^3 Mpc^{-1}. Furthermore we find the boost factor, which is crucial for the indirect detection of dark matter signals, is up to O(10^4) due to the bump that is allowed in the current observational bounds.