On the Heavy Relic Neutrino - Galactic Gamma Halo Connection

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A halo model with heavy relic neutrinos N belonging to a fourth generation and their annihilations in galactic halo may explain the recent evidence of diffused gamma (GeV) radiation around galactic plane. We considered a neutrino mass in the narrow range (MZ/2 < mₙ < MZ) and two main processes as source of gamma rays. A first one is ICS of ultrarelativistic electron pair on IR and optical galactic photons and a second due to prompt gammas by π⁰ decay, leading to a gamma flux (10⁻⁷ - 10⁻⁶ /(cm² s sr)) comparable to EGRET detection. Our predictions are also compatible with the narrow window of neutrino mass 45 GeV < mₙ < 60 GeV, required to explain the recent underground DAMA positive signals.