Dynamical scenarios with unstable neutrinos

Abstract

We describe a cosmological scenario with an unstable warm dark matter candidate (a heavy neutrino νH with mass of ~120 eV) which decays into a “hot” particle (a light nuetrino νL with mass of ~6 eV) and a relativistic boson. Theoretical and observational constraints on such a model are discussed. We note that (1) decay of νH disrupts the condensates made of primordial νL, lowering their mass to acceptable values of ~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 ~10-27 g cm-3 distributed over ~1 Mpc. We argued that the model agrees with observations at all scales.