CDM Accelerating Cosmology as an Alternative to LCDM model

TL;DR

This paper proposes a new cosmological model driven solely by baryons and cold dark matter, where accelerated expansion results from gravitationally-induced particle production, matching observations without a cosmological constant.

Contribution

It introduces a novel accelerating cosmology model based on particle production in cold dark matter, with only one free parameter and identical evolution equations to the $\\Lambda$CDM model.

Findings

The model fits supernovae data with a parameter $\\alpha \sim 0.71$.

Effectively observed matter density is $\\Omega_{meff} \sim 0.29$.

Consistent with weak lensing and large scale structure observations.

Abstract

A new accelerating cosmology driven only by baryons plus cold dark matter (CDM) is proposed in the framework of general relativity. In this model the present accelerating stage of the Universe is powered by the negative pressure describing the gravitationally-induced particle production of cold dark matter particles. This kind of scenario has only one free parameter and the differential equation governing the evolution of the scale factor is exactly the same of the $\Lambda$CDM model. For a spatially flat Universe, as predicted by inflation ($\Omega_{dm}+\Omega_{baryon}=1$), it is found that the effectively observed matter density parameter is $\Omega_{meff} = 1- \alpha$, where $\alpha$ is the constant parameter specifying the CDM particle creation rate. The supernovae test based on the Union data (2008) requires $\alpha\sim 0.71$ so that $\Omega_{meff} \sim 0.29$ as independently derived from weak gravitational lensing, the large scale structure and other complementary observations.