Late Decaying Dark Matter, Bulk Viscosity and the Cosmic Acceleration

TL;DR

This paper proposes a cosmological model where late-decaying dark matter induces bulk viscosity, leading to accelerated expansion consistent with supernova and age constraints, offering an alternative to dark energy.

Contribution

It introduces a novel model where decaying dark matter causes cosmic acceleration through bulk viscosity, aligning with key observational data.

Findings

Decaying dark matter can produce acceleration without dark energy.

Model fits supernova redshift-distance data.

Age of universe matches oldest stellar populations.

Abstract

We discuss a cosmology in which cold dark matter begins to decay into relativistic particles at a recent epoch (z < 1). We show that the large entropy production and associated bulk viscosity from such decays leads to an accelerating cosmology as required by observations. We investigate the effects of decaying cold dark matter in a Lambda = 0, flat, initially matter dominated cosmology. We show that this model satisfies the cosmological constraint from the redshift-distance relation for type Ia supernovae. The age in such models is also consistent with the constraints from the oldest stars and globular clusters. Possible candidates for this late decaying dark matter are suggested along with additional observational tests of this cosmological paradigm.