Cosmic Equation of State, Quintessence and Decaying Dark Matter
Abstract
Description
If CDM particles decay and their lifetime is comparable to the age of the Universe, they can modify its equation of state. By comparing the results of numerical simulations with high redshift SN-Ia observations we show that this hypothesis is consistent with present data. Fitting the simplest quintessence models with constant $w_q$ to data leads to $w_q \lesssim -1$. We show that a universe with a cosmological constant or quintessence matter with $w_q \sim -1$ and a decaying Dark Matter has an effective $w_q < -1$ and fits SN data better than stable CDM or quintessence models with $w_q > -1$.
5 pages, 3 figures. An appendix is added to define equivalent quintessence models
5 pages, 3 figures. An appendix is added to define equivalent quintessence models