Left–right symmetric models with a mixture of keV–TeV dark matter

We discuss the possibility of realising a multi-component dark matter scenario with widely separated dark matter masses: one having keV scale mass and the other with GeV-TeV scale mass, within the framework of left right symmetric models. Due to gauge interactions, both the dark matter candidates are produced thermally in the early Universe but overproducing the keV mass candidate. We consider one of the right handed neutrinos to be decaying at late epochs, just before the big bang nucleosynthesis, in order to dilute the thermally overproduced keV dark matter. We constrain the parameter space from the requirement of producing sub-dominant keV-TeV dark matter, satisfying indirect detection constraints from gamma ray searches and producing the tantalising 3.55 keV monochromatic X-ray line, reported by several groups to be present in galaxy and galaxy cluster data, from the decay of a 7.1 keV dark matter on cosmological scales. We find that these requirements can keep the right sector gauge boson masses around a few TeV while requiring some of the right-handed neutrinos in the sub-GeV regime.