Constraining Dark Matter with Cosmic-Ray and Gamma-Ray Observations
Title: Constraining Dark Matter with Cosmic-Ray and Gamma-Ray Observations
SNIC Project: SNIC 2020/6-177
Project Type: SNIC Medium Storage
Principal Investigator: Tim Linden <>
Affiliation: Stockholms universitet
Duration: 2020-10-01 – 2021-10-01
Classification: 10301


Weakly-interacting massive particles (WIMPs) stand among the most well-motivated candidates for particle dark matter. Moreover, the thermal-WIMP paradigm provides a natural target cross-section for indirect dark matter searches. Intriguingly, there are several excesses in gamma-ray and cosmic-ray data that are compatible with a 50-100 GeV thermal-WIMP annihilating to standard model particles. While each of these excesses is statistically significant, there are considerable systematic uncertainties in the astrophysical modeling that hampers the discovery of any dark matter signal. We propose a multi-faceted effort to improve our astrophysical background models to illuminate the thermal- WIMP parameter space. We will focus our efforts on three mature analyses which have sensitivities that lie very close to the critical parameter space: the Galactic center gamma-ray excess, the joint-likelihood analysis of dwarf spheroidal galaxies, and the cosmic-ray antiproton excess. Additionally, we will pursue a breakthrough opportunity provided by the potential observation of heavier cosmic-ray antinuclei by the AMS- 02 experiment. A key uncertainty common to each of these analyses is the inhomogeneity of cosmic-ray diffusion on small and moderate distance scales. Previous studies have typically utilized simplified models with homogeneous (averaged) diffusion models over the bulk of the Milky Way galaxy. While such models have successfully matched low-precision observations over the last decades, they are no longer adequate to fit the high-precision data provided by state-of-the art instruments. New, high-resolution and robust models are necessary to take advantage of current data and continue our search for dim dark matter signals. Combining the analyses from each study will maximize the scientific impact of our work. While the astrophysical uncertainties are significant -- the dominant astrophysical background in each detection channel differs, increasing the resilience of our study to systematic errors. This results of this study will produce the most sensitive indirect searches for 50-100 GeV dark matter particles, including either the detection, or exclusion of the Galactic center and antiproton excesses.