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 .