Isotropic extragalactic flux from dark matter annihilations: lessons
  from interacting dark matter scenarios
  The extragalactic gamma-ray and neutrino emission may have a contribution
from dark matter (DM) annihilations. In the case of discrepancies between
observations and standard predictions, one could infer the DM pair annihilation
cross section into cosmic rays by studying the shape of the energy spectrum. So
far all analyses of the extragalactic DM signal have assumed the standard
cosmological model (LambdaCDM) as the underlying theory. However, there are
alternative DM scenarios where the number of low-mass objects is significantly
suppressed. Therefore the characteristics of the gamma-ray and neutrino
emission in these models may differ from LambdaCDM as a result. Here we show
that the extragalactic isotropic signal in these alternative models has a
similar energy dependence to that in LambdaCDM, but the overall normalisation
is reduced. The similarities between the energy spectra combined with the flux
suppression could lead one to misinterpret possible evidence for models beyond
LambdaCDM as being due to CDM particles annihilating with a much weaker cross
section than expected.
