A cosmological concordance model with dynamical vacuum term

TL;DR

This paper proposes a cosmological model where dark matter particles are created at a constant rate, leading to a decaying cosmological term, and tests its consistency with various cosmological observations, offering an alternative to the standard DM model.

Contribution

It introduces a model with a linearly decaying vacuum term driven by dark matter creation, providing a new approach to cosmological dynamics and concordance.

Findings

The model fits CMB, SNIa, BAO, and LSS data well.

It requires a higher present matter density than DM.

The model offers insights into the cosmic coincidence problem.

Abstract

We demonstrate that creation of dark-matter particles at a constant rate implies the existence of a cosmological term that decays linearly with the Hubble rate. We discuss the cosmological model that arises in this context and test it against observations of the first acoustic peak in the cosmic microwave background (CMB) anisotropy spectrum, the Hubble diagram for supernovas of type Ia (SNIa), the distance scale of baryonic acoustic oscillations (BAO) and the distribution of large scale structures (LSS). We show that a good concordance is obtained, albeit with a higher value of the present matter abundance than in the \Lambda CDM model. We also comment on general features of the CMB anisotropy spectrum and on the cosmic coincidence problem.