# Signatures of Dipolar Dark Matter on Indirect Detection

## TL;DR

This paper investigates how fermionic dark matter with magnetic and electric dipole moments annihilates into photons, deriving constraints on these moments from relic density and cosmic microwave background data.

## Contribution

It provides a detailed calculation of the dark matter annihilation cross section considering dipole moments and constrains these moments using cosmological observations.

## Key findings

- Electric dipole moment of ~10^{-16} e cm needed for 100 GeV dark matter
- Constraints on dipole moments from cosmic microwave background measurements
- Effective cross section for gamma-ray production from dark matter annihilation

## Abstract

In this work we study the annihilation of fermionic dark matter, considering it as a neutral particle with non-vanishing magnetic ($M$) and electric ($D$) dipole moments. Effective cross section of the process $\chi \overline{\chi} \rightarrow \gamma \gamma$ is computed starting from a general form of the coupling $\chi \overline{\chi} \gamma$ in the framework of an extension of the Standard Model. By taking into account the annihilation of dark matter pairs into mono-energetic photons, we found that for masses of $O(10^2)$ GeV, an electric dipole moment $\sim 10^{-16}\, \textrm{e cm}$ is required to satisfy the current relic density inferences. Additionally, in order to pin down models viable to describe the physics of dark matter in the early Universe, we also constrain our model according to recent measurements of the temperature anisotropies of the cosmic microwave background radiation, and report constraints to the electric and magnetic dipole moments for a range of masses within our model.