# Search for Semi-Annihilating Dark Matter with Fermi-LAT, H.E.S.S., Planck, and the Cherenkov Telescope Array

## TL;DR

This paper investigates semi-annihilating dark matter models, deriving constraints from gamma-ray and cosmic background observations, and assesses future detection prospects with the Cherenkov Telescope Array.

## Contribution

It provides the first comprehensive indirect detection bounds for semi-annihilating dark matter across multiple channels and evaluates CTA's potential to detect such signals.

## Key findings

- Gamma-ray observations constrain semi-annihilation cross sections.
- Planck data limits dark matter interactions affecting cosmic background.
- CTA has promising sensitivity to semi-annihilation signals.

## Abstract

Dark matter annihilations have been fiercely restricted by the non-observation of excess events in indirect detection probes. Typically the interactions that dictate annihilation are also present in the dark matter-nucleon scattering cross section, also severely constrained by direct detection experiments. Semi-annihilations arise as a possible way to ameliorate the tension and even change the standard dark matter relic density calculation. In this work, we derive indirect detection bounds for several semi-annihilation channels including gauge bosons, the Higgs, leptophilic and leptophobic scalars. Our analysis is based on the gamma-ray observations in the direction of Dwarf Spheroidal Galaxies (Fermi-LAT) and the Galactic Center (H.E.S.S.), and Planck measurements of Cosmic Background Radiation. In addition, we derive the prospects for the Cherenkov Telescope Array (CTA) sensitivity to all these semi-annihilation modes.