A simplified approach for Chaplygin-type cosmologies

Abstract

A new class of accelerating cosmological models driven by a one-parameter version of the general Chaplygin-type equation of state is proposed. The simplified version is naturally obtained from causality considerations with basis on the adiabatic sound speed $v_S$ plus the observed accelerating stage of the universe. We show that very stringent constraints on the unique free parameter $\alpha$ describing the simplified Chaplygin model can be obtained from a joint analysis involving the latest SNe type Ia data and the recent Sloan Digital Sky Survey measurement of baryon acoustic oscillations (BAO). In our analysis we have considered separately the SNe type Ia gold sample measured by Riess et al. (2004) and the Supernova Legacy Survey (SNLS) from Astier et al. (2006). At 95.4% (c.l.), we find for BAO + \emph{gold} sample, $0.91\le \alpha \le 1.0$ and ${\Omega }_{\mathrm{M}}=0.28_{-0.048}^{+0.043}$ while BAO + SNLS analysis provides $0.94\le \alpha \le 1.0$ and ${\Omega }_{\mathrm{M}}=0.27_{-0.045}^{+0.048}$.

5 pages, 2 figures, LaTeX

References in corpus (4)

• Dynamics of dark energy
• The Supernova Legacy Survey: Measurement of Omega_M, Omega_Lambda and w from the First Year Data Set
• Generalized Chaplygin gas as a unified scenario of dark matter/energy: observational constraints
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