Constraint on the velocity dependent dark matter annihilation cross section from gamma-ray and kinematic observations of ultrafaint dwarf galaxies

TL;DR

This paper investigates how gamma-ray and kinematic data from ultrafaint dwarf galaxies can constrain velocity-dependent dark matter annihilation cross sections, especially p-wave scenarios, considering the correlation between density profiles and velocity dispersions.

Contribution

It introduces a method to incorporate the correlation between dark matter density and velocity dispersion in setting constraints on velocity-dependent annihilation cross sections using observational data.

Findings

Constraints on p-wave annihilation cross section derived from ultrafaint dwarf galaxies.

Analysis of the impact of velocity dispersion on gamma-ray flux calculations.

Uncertainty assessment from kinematic observations in the constraints.

Abstract

Searching for gamma rays from dwarf spheroidal galaxies (dSphs) is a promising approach to detect dark matter (DM) due to the high DM densities and low baryon components in dSphs. The Fermi-LAT observations from dSphs have set stringent constraints on the velocity independent annihilation cross section. However, the constraints from dSphs may change in velocity dependent annihilation scenarios because of the different velocity dispersions in galaxies. In this work, we study how to set constraints on the velocity dependent annihilation cross section from the combined Fermi-LAT observations of dSphs with the kinematic data. In order to calculate the gamma ray flux from the dSph, the correlation between the DM density profile and velocity dispersion at each position should be taken into account. We study such correlation and the relevant uncertainty from kinematic observations by performing a Jeans analysis. Using the observational results of three ultrafaint dSphs with large J-factors, including Willman 1, Reticulum II, and Triangulum II, we set constraints on the p-wave annihilation cross section in the Galaxy as an example.