Dark energy with non-adiabatic sound speed: initial conditions and detectability
- Museo Storico della Fisica e Centro Studi e Ricerche ''Enrico Fermi'', Piazza del Viminale 1, I-00184, Rome (Italy)
- CERN, Theory Division, CH-1211 Geneva 23 (Switzerland)
Assuming that the universe contains a dark energy fluid with a constant linear equation of state and a constant sound speed, we study the prospects of detecting dark energy perturbations using CMB data from Planck, cross-correlated with galaxy distribution maps from a survey like LSST. We update previous estimates by carrying a full exploration of the mock data likelihood for key fiducial models. We find that it will only be possible to exclude values of the sound speed very close to zero, while Planck data alone is not powerful enough for achieving any detection, even with lensing extraction. We also discuss the issue of initial conditions for dark energy perturbations in the radiation and matter epochs, generalizing the usual adiabatic conditions to include the sound speed effect. However, for most purposes, the existence of attractor solutions renders the perturbation evolution nearly independent of these initial conditions.
- OSTI ID:
- 22275347
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2010, Issue 10; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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