Abstract

Dark Matter (DM) constitutes most of the matter in the presently accepted cosmological model for our Universe. However, despite the increased sensitivity of experimental searches, no signal from DM particles has been detected so far. Conventional indirect searches look for an excess of photons from DM self-annihilation in high DM density regions but their polarisation has so far not been explored.

In this talk, I will argue that the photon polarisation is an important feature to understand new physics interactions. In particular, circular polarisation can be generated from Beyond the Standard Model interactions if they violate parity and there is an asymmetry in the number of particles which participate in the interaction.

I will consider a simplified model where the DM candidate is a Majorana fermion which interacts with right-handed electrons via a scalar mediator and study photon signatures from high density sources such as the Galactic Centre and the active galactic nuclei of Centaurus A. Particular stress is given to the possibility of detecting circular polarised signals from the interaction of DM with high energy electrons, finding that the degree of polarization can reach up to values of 90-100%. Taking into account current experimental constraints, I will estimate the required sensitivity from future experiments to detect this signal.

Finally, since the origin of the photons in the GeV-TeV range from Centaurus A is not completely clear and an exotic origin is compatible with the observations, I will show that this excess could be explained with signals from DM annihilation.