Small Scale Isocurvature Perturbation of Weakly Interacting Massive Particle

Ki-Young Choi,Chang Sub Shin,Jinn-Ouk Gong

doi:10.1142/s2010194516602027

Abstract

It is known that the smallest size of the structures of the Universe with the weakly interacting massive dark matter is determined by the scale that enters the Hubble horizon at the time of kinetic decoupling of WIMP. This comes from the fact that the perturbation at smaller scales is erased due to the collisional damping during the kinetic decoupling. However the isocurvature mode is not affected and continue to be constant. We discuss about the generation of the isocurvature mode of WIMP dark matter at small scales recently found by Choi, Gong, and Shin1 and its implications for the indirect detection of dark matter through the formation of the small size of halos.

Highlights

It is known that the smallest size of the structures of the Universe with the weakly interacting massive dark matter is determined by the scale that enters the Hubble horizon at the time of kinetic decoupling of weakly interacting massive particle (WIMP)
We discuss about the generation of the isocurvature mode of WIMP dark matter at small scales recently found by Choi, Gong, and Shin[1] and its implications for the indirect detection of dark matter through the formation of the small size of halos
Shin microwave background (CMB) temperature anisotropy, which constrains the power spectrum of the isocurvature mode between dark matter and radiation to be smaller than a few percent compared to the adiabatic one.[3]

Summary

Introduction

It is known that the smallest size of the structures of the Universe with the weakly interacting massive dark matter is determined by the scale that enters the Hubble horizon at the time of kinetic decoupling of WIMP. We discuss about the generation of the isocurvature mode of WIMP dark matter at small scales recently found by Choi, Gong, and Shin[1] and its implications for the indirect detection of dark matter through the formation of the small size of halos. During the kinetic decoupling process, the adiabatic mode of dark matter are erased due to the collisional damping and the structures of the smaller size hardly form.[6,7,8,9]

Results

Conclusion