  Conventional indirect dark matter (DM) searches look for an excess in the
electromagnetic emission from the sky that cannot be attributed to known
astrophysical sources. Here, we argue that the photon polarisation is an
important feature to understand new physics interactions and can be exploited
to improve our sensitivity to DM. 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. In this work, we consider a simplified model for fermionic
(Majorana) DM and study the circularly polarised gamma rays below 10 GeV from
the scattering of cosmic ray electrons on DM. We calculate the differential
flux of positive and negative polarised photons from the Galactic Center and
show that the degree of circular polarization can reach up to 90%. Finally,
once collider and DM constraints have been taken into account, we estimate the
required sensitivity from future experiments to detect this signal finding
that, although a distinctive peak will be present in the photon flux spectrum,
a near future observation is unlikely. However, different sources or models not
considered in this work could provide higher intensity fluxes, leading to a
possible detection by e-ASTROGAM. In the event of a discovery, we argue that
the polarisation fraction is a valuable characterisation feature of the new
sector.
