Dark matter around primordial black hole at the radiation-dominated stage

TL;DR

This paper investigates how dark matter accumulates around primordial black holes during the radiation-dominated era, leading to density spikes that could produce gamma-ray signals, with a new self-consistent model and numerical analysis.

Contribution

It provides a self-consistent derivation of dark matter density profiles around primordial black holes during the radiation era, improving upon previous models.

Findings

Density growth is suppressed in the central region compared to earlier estimates.

The derived density profiles can inform gamma-ray observational searches.

Numerical solutions reveal the structure of dark matter spikes around primordial black holes.

Abstract

The accumulation of dark matter particles near the primordial black holes starts at the radiation-dominated cosmological stage and produces the central density spikes. The spikes can be the bright gamma-ray sources due to dark matter annihilation. We present the self-consistent derivation of the equation of motion of particle in the metrics of primordial black hole immersed into cosmological background. By numerical solution of this equation we find the central dark matter density profile. The density growth is suppressed in the central part of the profile compared with previous calculations.