Constraints on the sound speed of dark energy

Steen Hannestad
Phys. Rev. D 71, 103519 – Published 24 May 2005

Abstract

We have studied constraints on the equation of state, w, and speed of sound, cs, of the dark energy from a joint analysis of data from the cosmic microwave background, large scale structure and type-Ia supernovae. We find that current observations have no significant sensitivity to cs. However, there is a slight difference between models in which there are no dark energy perturbations and models in which dark energy behaves as a fluid. Assuming that there are no dark energy perturbations shifts the allowed region for w to slightly higher values. At present models with and without dark energy perturbations provide roughly equally good fits to observations, but the difference is potentially important for future parameter estimations. Finally, we have also performed error forecasts for future measurements of cs.

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  • Received 6 April 2005

DOI:https://doi.org/10.1103/PhysRevD.71.103519

©2005 American Physical Society

Authors & Affiliations

Steen Hannestad

  • Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark

  • *Electronic address: sth@phys.au.dk

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Issue

Vol. 71, Iss. 10 — 15 May 2005

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