  Recently, an interesting indication for a dark matter signal in the form of a
narrow line, or maybe two lines and/or an internal bremsstrahlung feature, has
been found in data from the Fermi-LAT satellite detector. As recent analyses
have also shown that there is little sign of extra contributions to continuum
photons, it is natural to investigate leptophilic interacting massive particle
(LIMP) models. We show that a model of radiatively generated neutrino masses
may have the properties needed to explain the Fermi-LAT structure around 130
GeV. This model was proposed some 10 years ago, and predicted a clearly
observable $\gamma$-ray signal in the Fermi-LAT (then GLAST) detector. Here, we
update and improve that analysis, and show as an example that a right-handed
neutrino of mass 135 GeV should give rise to three conspicuous effects: a broad
internal bremsstrahlung bump with maximum around 120 GeV, a 2$\gamma$ line
around 135 GeV, and a $Z\gamma$ line at 119.6 GeV (neglected in the previous
work). These features together give a good fit to the 130 GeV structure, given
the present energy resolution of the Fermi-LAT data. An attractive feature of
the model is that the particle physics properties are essentially fixed, when
relic density and mass of the right-handed neutrino dark matter particle have
been set. Puzzling features of the data at present are a slight displacement of
the signal from the galactic center, and a needed boost factor of order 5-15.
This presents a challenge for numerical simulations including both baryons and
dark matter on scales of 100 pc, and perhaps a need to go beyond the simplest
halo models. With upcoming data, the double-peak structure with the two lines
and the internal bremsstrahlung feature should be seen, if this model is
correct. With the satellite GAMMA-400, a striking fingerprint of this dark
matter candidate should then appear.
