Search for Gamma-ray Emission from Dark Matter Annihilation in the Small Magellanic Cloud with the Fermi Large Area Telescope

TL;DR

This study used six years of Fermi LAT data to search for gamma-ray signals from dark matter annihilation in the Small Magellanic Cloud, setting limits on the annihilation cross section due to no detection.

Contribution

It provides the first comprehensive gamma-ray search for dark matter in the SMC using extensive Fermi LAT data and improved background modeling.

Findings

No dark matter signal detected in the SMC.

Set upper limits on the dark matter annihilation cross section.

Constraints approach canonical thermal relic cross section for masses below 10 GeV.

Abstract

The Small Magellanic Cloud (SMC) is the second-largest satellite galaxy of the Milky Way and is only 60 kpc away. As a nearby, massive, and dense object with relatively low astrophysical backgrounds, it is a natural target for dark matter indirect detection searches. In this work, we use six years of Pass 8 data from the Fermi Large Area Telescope to search for gamma-ray signals of dark matter annihilation in the SMC. Using data-driven fits to the gamma-ray backgrounds, and a combination of N-body simulations and direct measurements of rotation curves to estimate the SMC DM density profile, we found that the SMC was well described by standard astrophysical sources, and no signal from dark matter annihilation was detected. We set conservative upper limits on the dark matter annihilation cross section. These constraints are in agreement with stronger constraints set by searches in the Large Magellanic Cloud and approach the canonical thermal relic cross section at dark matter masses lower than 10 GeV in the $b\bar{b}$ and $\tau^+\tau^-$ channels.