Common Origin of 3.55 keV X-Ray Line and Galactic Center Gamma Ray
  Excess in a Radiative Neutrino Mass Model
  We attempt to simultaneously explain the recently observed 3.55 keV X-ray
line in the analysis of XMM-Newton telescope data and the galactic center gamma
ray excess observed by the Fermi gamma ray space telescope within an abelian
gauge extension of standard model. We consider a two component dark matter
scenario with tree level mass difference 3.55 keV such that the heavier one can
decay into the lighter one and a photon with energy 3.55 keV. The lighter dark
matter candidate is protected from decaying into the standard model particles
by a remnant $Z_2$ symmetry into which the abelian gauge symmetry gets
spontaneously broken. If the mass of the dark matter particle is chosen to be
within $31-40$ GeV, then this model can also explain the galactic center gamma
ray excess if the dark matter annihilation into $b\bar{b}$ pairs has a cross
section of $\langle \sigma v \rangle \simeq (1.4-2.0) \times 10^{-26} \;
\text{cm}^3/\text{s}$. We constrain the model from the requirement of producing
correct dark matter relic density, 3.55 keV X-ray line flux and galactic center
gamma ray excess. We also impose the bounds coming from dark matter direct
detection experiments as well as collider limits on additional gauge boson mass
and gauge coupling. We also briefly discuss how this model can give rise to
sub-eV neutrino masses at tree level as well as one-loop level while keeping
the dark matter mass at few tens of GeV. We also constrain the model parameters
from the requirement of keeping the one-loop mass difference between two dark
matter particles below a keV. We find that the constraints from light neutrino
mass and keV mass splitting between two dark matter components show more
preference for opposite $CP$ eigenvalues of the two fermion singlet dark matter
candidates in the model
