Contribution of dark matter annihilation to gamma-ray burst afterglows near massive galaxy centers

TL;DR

This paper explores how dark matter annihilation could influence gamma-ray burst afterglows, especially in low-electron-density environments near massive galaxy centers, by modeling light curves and spectra under various dark matter parameters.

Contribution

It provides a detailed analysis of dark matter's potential impact on GRB afterglow emissions, considering different dark matter densities and annihilation channels, which is a novel approach.

Findings

Dark matter can significantly alter afterglow spectra in low-electron-density environments.

Detectable effects are likely near galaxy centers with high dark matter density.

GRB afterglows with dark matter influence may occur within several to tens of parsecs from galaxy centers.

Abstract

Gamma-ray bursts (GRBs) are believed to be powered by ultrarelativistic jets. If these jets encounter and accelerate excess electrons and positrons produced by particle dark matter (DM) annihilation, the observed electromagnetic radiation would be enhanced. In this paper, we study GRB afterglow emission with the presence of abundant DM under the weakly interacting massive particle annihilation conditions. We calculate the light curves and spectra of the GRB afterglows with different parameters, i.e., DM density, particle DM mass, annihilation channel, and electron density of the interstellar medium. We find that the effect of DM may become noticeable in the afterglow spectra if the circumburst has a low electron number density ($n \lesssim 0.1~\rm cm^{-3}$) and if the DM has a high number density ($\rho_\chi \gtrsim 10^3~\rm GeV~cm^{-3}$). According to the standard galaxy DM density profile, GRB afterglows with DM contribution might occur at distances of several to tens of parsecs from the centers of massive galaxies.