arXiv subjects

R. de Sá Ribeiro

Publications and source records attributed to R. de Sá Ribeiro.

2 recordsLinked to original sources

arXiv2003

Generalized Chaplygin gas with $α= 0$ and the $ΛCDM$ cosmological model

The generalized Chaplygin gas model is characterized by the equation of state $p = - \frac{A}{ρ^α}$. It is generally stated that the case $α= 0$ is equivalent to a model with cosmological constant and dust ($ΛCDM$). In this work we show that, if this is true for the background equations, this is not true for the perturbation equations. Hence, the mass spectrum predicted for both models may differ.

astro-ph↗

arXiv2000

A remark on Brans-Dicke dust cosmological solutions with negative $ω$

Analysing the Brans-Dicke solutions for the dust phase, we show that, for negative values of $ω$, they contain scenarios that display an initial subluminal expansion followed by an inflationary phase. We discuss these solutions with respect to the results of the observation of high redshif supernova as well as the age problem and structure formation. We stablish possible connections of these solutions with those emerging from string effective models.

gr-qc↗