A note on observational signatures in superluminal unified dark matter models

Journal Article · Thu Jul 01 04:00:00 EDT 2010 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2010/07/027· OSTI ID:22272796

Urakawa, Yuko; Kobayashi, Tsutomu ^[1]

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1. Department of Physics, Waseda University, Okubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan)

We explore the possibility that the dark matter and dark energy are mimicked by a single fluid or by a single k-essence-like scalar field. The so called Chaplygin gas unified dark matter models can reproduce the observed matter power spectrum by adding a baryon component. It has been argued that the evolution of the baryon fluctuations is particularly favoured for the ''superluminal'' case where the sound speed of the Chaplygin gas exceeds the speed of light at late times, as well as for the models with the negligibly small sound speed. In this note we compute the integrated Sachs-Wolfe signal in the Chaplygin gas models, focusing on the superluminal case which has not been investigated before because of the premature understanding of causality. It is shown that the superluminal model leads to large enhancement of the integrated Sachs-Wolfe effect, which is inconsistent with the CMB measurements.

• OSTI ID: 22272796
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 07 Vol. 2010; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BARYONS
CAUSALITY
COSMOLOGICAL MODELS
COSMOLOGY
ENERGY SPECTRA
FLUCTUATIONS
NONLUMINOUS MATTER
SCALAR FIELDS
SOUND WAVES
VELOCITY
VISIBLE RADIATION