Polarization of photons emitted by decaying dark matter

TL;DR

This paper investigates whether the polarization of photons emitted by decaying dark matter can reveal properties of dark matter, finding that asymmetric Dirac fermion dark matter produces circular polarization, unlike symmetric models.

Contribution

It demonstrates that photon polarization can distinguish asymmetric dark matter models, specifically Dirac fermions, from symmetric ones, which are polarization-indistinguishable.

Findings

Symmetric dark matter models are polarization-indistinguishable.

Asymmetric Dirac fermion dark matter produces circularly polarized photons.

Photon polarization can potentially constrain dark matter properties.

Abstract

Radiatively decaying dark matter may be searched through investigating the photon spectrum of galaxies and galaxy clusters. We explore whether the properties of dark matter can be constrained through the study of a polarization state of emitted photons. Starting from the basic principles of quantum mechanics we show that the models of symmetric dark matter are indiscernible by the photon polarization. However, we find that the asymmetric dark matter consisted of Dirac fermions is a source of circularly polarized photons, calling for the experimental determination of the photon state.