  We consider a simple extension of the Standard Model to consistently explain
the observation of a peak in the galactic X-ray spectrum at 3.55 keV and the
light neutrino masses along with the baryon asymmetry of the universe. The
baryon asymmetry is generated through leptogenesis, the lepton asymmetry being
generated by the decay of a heavy neutrino with TeV mass scale. The extra
singlet fermion introduced in the model can be identified as a dark matter
candidate of mass 7.1 keV. It decays with a lifetime much larger than the age
of the universe, producing a final state photon. The Yukawa interactions
between the extra singlet neutrino and a heavier right-handed neutrino play a
crucial role in simultaneously achieving low scale leptogenesis and relic
density of the keV dark matter candidate.
