Dark Matter implications of the Fermi-LAT measurement of anisotropies in the diffuse gamma-ray background: status report

TL;DR

This paper analyzes Fermi-LAT gamma-ray anisotropy data to constrain dark matter models, incorporating detailed simulations of dark matter distribution and considering foreground uncertainties.

Contribution

It introduces a comprehensive method combining N-body simulation-based dark matter templates with Fermi-LAT data to derive constraints on dark matter particle properties.

Findings

Compatibility of data with known sources plus deviations at certain scales

Constraints on dark matter annihilation and decay parameters

Assessment of systematic uncertainties from galactic foreground modeling

Abstract

For the first time, the Fermi-LAT measured the angular power spectrum (APS) of anisotropies in the diffuse gamma-ray background. The data is found to be broadly compatible with a model with contributions from the point sources in the 1-year catalog, the galactic diffuse background, and the extragalactic isotropic emission; however deviations are present at both large and small angular scales. In this study, we complement the model with a contribution from Dark Matter (DM) whose distribution is modeled exploiting the results of the most recent N-body simulations, considering the contribution of extragalactic halos and subhalos (from Millennium-II) and of galactic substructures (from Aquarius). With the use of the Fermi Science Tools, these simulations serve as templates to produce mock gamma-ray count maps for DM gamma-ray emission, both in the case of an annihilating and a decaying DM candidate. The APS will then be computed and compared with the Fermi-LAT results to derive constraints on the DM particle physics properties. The possible systematic due to an imperfect model of the galactic foreground is also studied and taken into account properly. The present paper reports on the status of the project.