Gamma Rays From Dark Matter Subhalos Revisited: Refining the Predictions and Constraints

TL;DR

This paper refines predictions for gamma-ray signals from dark matter subhalos using simulations, revealing altered subhalo shapes and setting new constraints on dark matter properties based on Fermi data.

Contribution

It introduces updated models of dark matter subhalo profiles considering tidal effects, improving flux predictions and constraints from gamma-ray observations.

Findings

Subhalo shapes are significantly affected by tidal effects.

Predicted gamma-ray fluxes are refined with new density profiles.

Constraints on dark matter annihilation cross section are established.

Abstract

Utilizing data from the ELVIS and Via Lactea-II simulations, we characterize the local dark matter subhalo population, and use this information to refine the predictions for the gamma-ray fluxes arising from annihilating dark matter in this class of objects. We find that the shapes of nearby subhalos are significantly altered by tidal effects, and are generally not well described by NFW density profiles, instead prefering power-law profiles with an exponential cutoff. From the subhalo candidates detected by the Fermi Gamma-Ray Space Telescope, we place limits on the dark matter annihilation cross section that are only modestly weaker than those based on observations of dwarf galaxies. We also calculate the fraction of observable subhalos that are predicted to be spatially extended at a level potentially discernible to Fermi.