Dark Matter Identification using Gamma Rays from Dwarf Galaxies

TL;DR

This paper explores the potential of atmospheric Cherenkov telescopes to detect gamma rays from dark matter annihilation in dwarf galaxies, aiming to identify dark matter properties through FSR photon spectra.

Contribution

It demonstrates that current and upcoming ACTs can effectively detect and distinguish dark matter annihilation signals in dwarf galaxies, despite uncertainties in dark matter distribution.

Findings

ACTs have high potential for detecting FSR photons from dark matter.

Models with different lepton final states can be distinguished via FSR spectra.

Dark matter particle mass can be accurately estimated from observations.

Abstract

If the positron fraction and combined electron-positron flux excesses recently observed by PAMELA, Fermi and HESS have a dark matter origin, final state radiation (FSR) photons from dark matter annihilation into lepton-rich final states may be detected with observations of satellite dwarf galaxies of the Milky Way by ground-based atmospheric Cherenkov telescopes (ACTs). We find that current and near-future ACTs have excellent potential for such detection, although a discovery cannot be guaranteed due to large uncertainties in the distribution of dark matter within the dwarfs. We find that models predicting dark matter annihilation into two-lepton final states and those favoring four-lepton final states (as in, for example, "axion portal" models) can be reliably distinguished using the FSR photon spectrum once measured, and the dark matter particle mass can also be accurately determined.