The Dark Matter Annihilation Signal from Dwarf Galaxies and Subhalos

TL;DR

This paper reviews the potential gamma-ray signals from dark matter annihilation in Galactic subhalos, highlighting promising dwarf galaxies and the likelihood of detecting numerous dark clumps, thus probing the Galactic halo's structure.

Contribution

It provides an estimation of gamma-ray fluxes from known dwarf galaxies and predicts the existence of many dark subhalos, advancing the search for dark matter signals.

Findings

Segue 1 is the most promising source.

Detection of known satellites implies many dark clumps are detectable.

Numerical simulations estimate fluxes for 18 dwarf spheroidals.

Abstract

Dark Matter annihilation holds great potential for directly probing the clumpiness of the Galactic halo that is one of the key predictions of the Cold Dark Matter paradigm of hierarchical structure formation. Here we review the gamma-ray signal arising from dark matter annihilation in the centers of Galactic subhalos. We consider both known Galactic dwarf satellite galaxies and dark clumps without a stellar component as potential sources. Utilizing the Via Lactea II numerical simulation, we estimate fluxes for 18 Galactic dwarf spheroidals with published central densities. The most promising source is Segue 1, followed by Ursa Major II, Ursa Minor, Draco, and Carina. We show that if any of the known Galactic satellites can be detected, then at least ten times more subhalos should be visible, with a significant fraction of them being dark clumps.