Key points are not available for this paper at this time.
We consider a cosmological model in which an unstable massive relic particle species (denoted by X) has an initial mass density relative to baryons ^-1ₗ/₁1, and then decays recently (red-shift z1000) into particles which are still relativistic today (denoted by R). We write down and solve the coupled equations for the cosmic scale factor a (t), the energy density in the various components (ₗ, ₑ, ₁), and the growth of linear density perturbations (/). The solutions form a one-parameter () family of solutions; physically ^-1 (ₑ/₍ₑ) (₁+ₙ₃) = (ratio today of energy density of relativistic to nonrelativistic particles) (1+ red-shift of decay). We discuss the observational implications of such a cosmological model and compare our results to earlier results computed in ``the simultaneous decay approximation. '' In an appendix we briefly consider the case where one of the decay products of the X is massive and becomes nonrelativistic by the present epoch.
Michael S. Turner (1985) studied this question.