2003/04/30 by L. Amendola, Luca Amendola, F. Finelli +3 · 275 citations
Physics and Astronomy · #Adiabatic process #Astrophysics #CMB cold spot #Chaplygin gas #Cosmic microwave background #Cosmology #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dark energy #Dark fluid #Dark matter #Equation of state #Galaxies: Formation, Evolution, Phenomena #Mathematical physics #Omega #Physics #Polytropic process #Quantum mechanics #Sigma #astro-ph #gr-qc #hep-ph
paper · pdf · doi:10.1088/1475-7516/2003/07/005
published in Journal of Cosmology and Astroparticle Physics 2003(07), 005 (Institute of Physics) · 10 pages, 8 figures, results clarified
arxiv created 2003/05/06 · openalex publication_date 2003/07/08 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
We compare the WMAP temperature power spectrum and SNIa data to models with a generalized Chaplygin gas as dark energy. The generalized Chaplygin gas is a component with an exotic equation of state, p X = − A /ρ α X (a polytropic gas with negative constant and exponent). Our main result is that, restricting to a flat universe and to adiabatic pressure perturbations for the generalized Chaplygin gas, the constraints at 95% CL to the present equation of state w X = p X /ρ X and to the parameter α are −1 ⩽ w X < −0.8, 0 ⩽ α < 0.2, respectively. Moreover, we show that a Chaplygin gas (α = 1) is ruled out as a candidate for dark energy by our analysis at more than the 99.99% CL. A generalized Chaplygin gas appears much less likely as a unified dark matter candidate (Ω CDM = 0) than as a dark energy model, although its χ 2 is only two sigma away from the expected value.