Constraints on dark matter scattering with long lived mediators from observations of the Sun with the Fermi Large Area Telescope

TL;DR

This study uses 13.5 years of Fermi LAT data to search for gamma-ray signals from dark matter annihilations involving long-lived mediators in the Sun, setting new constraints on dark matter interactions.

Contribution

It provides the first constraints on dark matter-nucleon scattering cross sections considering long-lived mediators and gamma-ray signals from the Sun.

Findings

No significant gamma-ray excess detected.

Upper limits on spin-dependent cross sections range from 10^{-45} to 10^{-39} cm^2.

Upper limits on spin-independent cross sections range from 10^{-47} to 10^{-42} cm^2.

Abstract

The Sun represents a promising target for indirect dark matter searches, as dark matter particles from the Galactic halo can be gravitationally trapped in its core or in external orbits, and their annihilations can lead to final states with standard model particles that are able to reach the Earth. In this work we have considered a scenario in which dark matter particles can annihilate into pairs of long-lived mediators, which in turn can escape from the Sun and decay into pairs of gamma rays or into the $b\bar{b}$, $\tau^{+}\tau^{-}$, $\mu^{+}\mu^{-}$ channels, with the production of gamma rays in the final states. All these processes are expected to yield an excess in the energy spectrum of gamma rays towards the Sun. We have therefore analyzed the data collected by the Fermi Large Area Telescope during its first 13.5 years of operation, searching for possible excesses in the solar gamma-ray spectrum. Since no statistically significant excess is found, we have set constraints on the dark matter-nucleon scattering cross sections in both the spin-dependent and spin-independent cases. For all the mediator decay channels explored and for dark matter masses between a few GeV/c${^2}$ and 1 TeV/c${^2}$, we have found that the upper limits on the spin-dependent and spin-independent cross sections are in the ranges from $10^{-45}$ to $10^{-39}$ cm$^{2}$ and from $10^{-47}$ up to $10^{-42}$ cm$^{2}$, respectively.