Novel Gamma-Ray Signatures of PeV-Scale Dark Matter

TL;DR

This paper investigates how gamma-ray signals from extremely heavy dark matter particles are affected by electromagnetic cascades, influencing their spectral and angular features, especially relevant for observations with the HAWC experiment.

Contribution

It provides detailed calculations of gamma-ray spectral and angular distributions from PeV-scale dark matter in dwarf galaxies and galaxy clusters, considering attenuation effects.

Findings

Gamma-ray spectra are significantly altered by electromagnetic cascades.

Angular distributions of gamma-rays are affected by pair production attenuation.

Results are relevant for interpreting data from the HAWC experiment.

Abstract

The gamma-ray annihilation and decay products of very heavy dark matter particles can undergo attenuation through pair production, leading to the development of electromagnetic cascades. This has a significant impact not only on the spectral shape of the gamma-ray signal, but also on the angular distribution of the observed photons. Such phenomena are particularly important in light of the new HAWC experiment, which provides unprecedented sensitivity to multi-TeV photons and thus to very heavy dark matter particles. In this study, we focus on dark matter in the 100 TeV-100 PeV mass range, and calculate the spectral and angular distribution of gamma-rays from dwarf galaxies and from nearby galaxy clusters in this class of models.