The Most Dark Matter Dominated Galaxies: Predicted Gamma-ray Signals from the Faintest Milky Way Dwarfs

TL;DR

This paper predicts gamma-ray signals from the faintest, most dark matter dominated Milky Way dwarf galaxies using recent kinematic data, highlighting their potential as prime targets for dark matter detection.

Contribution

It provides new constraints on dark matter halos of ultra-faint dwarfs and predicts their gamma-ray fluxes, emphasizing their significance in dark matter research.

Findings

Ultra-faint dwarfs are the most dark matter dominated galaxies.

Predicted gamma-ray fluxes are comparable to or greater than other satellites.

Fluxes could be boosted significantly by dark matter substructure.

Abstract

We use kinematic data from three new, nearby, extremely low-luminosity Milky Way dwarf galaxies (Ursa Major II, Willman 1, and Coma Berenices) to constrain the properties of their dark matter halos, and from these make predictions for the gamma-ray flux from annihilation of dark matter particles in these halos. We show that these 10^3 solar luminosity dwarfs are the most dark matter dominated galaxies in the Universe, with total masses within 100 pc in excess of 10^6 solar masses. Coupled with their relative proximity, their large masses imply that they should have mean gamma-ray fluxes comparable to or greater than any other known satellite galaxy of the Milky Way. Our results are robust to both variations of the inner slope of the density profile and the effect of tidal interactions. The fluxes could be boosted by up to two orders of magnitude if we include the density enhancements caused by surviving dark matter substructure.