Dynamical scenarios with unstable heavy neutrino

Abstract

A cosmological scenario with an unstable warm dark matter candidate (a heavy neutrino ν_H with mass of about 120 eV) which decays into a 'hot' particle (a light nuetrino ν_L with mass of about ~6 eV) and a relativistic boson is described. Theoretical and observational constraints on such a model are discussed. It is noted that decay of ν_H disrupts the condensates made of primordial ν_L, lowering their mass to acceptable values of about ~10¹² M^⊙. (2) The relativistic boson can contribute nearly 0.25 to the total density in a 'recent' decay. The model predicts two prominent scales in dark matter distribution: (i) a mass of about ~4 × 10¹²M^⊙ around the galaxies, distributed over about ~200 kpc, and (ii)a smoother density of about ~10^-27 g cm^-3 distributed over about ~1 Mpc. It is argued that the model agrees with observations at all scales.