Asymmetric Dark Matter in the Shear--dominated Universe

TL;DR

This paper investigates how anisotropic, shear-dominated expansion of the universe affects the relic abundance of asymmetric Dark Matter, revealing increased relic densities and conditions for indirect detection.

Contribution

It introduces a model considering anisotropic expansion's impact on asymmetric Dark Matter relic density, providing new constraints on model parameters.

Findings

Relic abundances increase in shear-dominated universe.

Particle and antiparticle abundances become nearly equal at high shear.

Constraints on model parameters are derived from current Dark Matter observations.

Abstract

We explore the relic abundance of asymmetric Dark Matter in shear--dominated universe in which it is assumed the universe is expanded anisotropically. The modified expansion rate leaves its imprint on the relic density of asymmetric Dark Matter particles if the asymmetric Dark Matter particles are decoupled in shear dominated era. We found the relic abundances for particle and anti--particle are increased. The particle and anti--particle abundances are almost in the same amount for the larger value of the shear factor $x_e$ which makes the indirect detection possible for asymmetric Dark Matter. We use the present day Dark Matter density from the observation to find the constraints on the parameter space in this model.