Searching for dark matter in X-rays: how not to check the dark matter
  origin of a spectral feature
  In a recent preprint entitled "Searching for dark matter in X-rays: how to
check the dark matter origin of a spectral feature" [arXiv:1001.0644v1], the
authors have claimed that some archival X-ray data could be used to rule out
dark matter in the form of 5-keV sterile neutrinos at the level of 20 sigma.
Unfortunately, the limit was derived incorrectly. We point out the shortcomings
of this analysis and show that the tentative detection of a spectral feature
consistent with a 5-keV sterile neutrino is not in contradiction with existing
limits. Future observations of dwarf spheroidal galaxies will test this
hypothesis.
