  Here I present the extension to ${\nu}$MSM model by adding a $U(1)'$ gauge
symmetry under which right-handed fermions including sterile neutrinos and
exotic Higgs scalar are charged. This model explains 3.5 keV line observed by
XMM-Newton telescope as well as Galactic Center Excess(GCE) detected by
Fermi-LAT satellite. The proposed model also accounts for recent diphoton
excess of mass around 750 GeV produced in ATLAS and CMS detectors. Cosmological
inconsistencies such as baryon asymmetry can also be explained. Verification of
presented model is possible with current experimental techniques and
limitations. Careful validation and analysis of the model needs to be done in
future.
