Prospects for measuring dark matter microphysics with observations of dwarf spheroidal galaxies

TL;DR

This paper explores how gamma-ray observations of dwarf spheroidal galaxies can be used to determine the velocity dependence of dark matter annihilation cross sections, emphasizing the need for improved density profile constraints.

Contribution

It demonstrates the potential to measure dark matter annihilation velocity dependence through gamma-ray signals from dwarf galaxies, highlighting the importance of reducing systematic uncertainties.

Findings

Future experiments can constrain velocity-dependent annihilation cross sections.

Improved density profile measurements are crucial for accurate constraints.

Systematic uncertainties significantly impact the ability to determine dark matter properties.

Abstract

Dark matter annihilation in dwarf spheroidal (dSph) galaxies near the Milky Way has the potential to produce a detectable signature in gamma-rays. The amplitude of this signal depends on the dark matter density in a dSph, the dark matter particle mass, the number of photons produced in an annihilation, and the possibly velocity-dependent dark matter annihilation cross section. We argue that if the amplitude of the annihilation signal from multiple dSphs can be measured, it is possible to determine the velocity-dependence of the annihilation cross section. However, we show that doing so will require improved constraints on the dSph density profiles, including control of possible sources of systematic uncertainty. Making reasonable assumptions about future improvements, we make forecasts for the ability of current and future experiments -- including Fermi, CTA and AMEGO -- to constrain the dark matter annihilation velocity dependence.