Probing dark energy perturbations: The dark energy equation of state and speed of sound as measured by WMAP

By R. Bean, O. Dor'e. 2003

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We review the implications of having a nontrivial matter component in the Universe and the potential for detecting such a component through the matter power spectrum and integrated Sachs-Wolfe effect. We adopt a phenomenological approach and consider the mysterious dark energy to be a cosmic fluid. It is thus fully characterized, up to linear order, by its equation of state and its speed of sound. Whereas the equation of state has been widely studied in the literature, less interest has been devoted to the speed of sound. Its observational consequences come predominantly from very large scale modes of dark matter perturbations $(kl0.01h{\mathrm{Mpc}}^{\ensuremath{-}1}).$ Since these modes have hardly been probed so far by large scale galaxy surveys, we investigate whether joint constraints can be placed on those two quantities using the recent cosmic microwave background (CMB) fluctuations measurements by the Wilkinson Microwave Anisotropy Probe as well as the recently measured CMB large scale structure cross correlation. We find only a tentative 1 sigma detection of the speed of sound, from CMB alone, ${c}_{s}^{2}l0.04$ at this low significance level. Furthermore, the current uncertainties in bias in the matter power spectrum preclude any constraints being placed using the cross correlation of CMB with the NRAO VLA Sky Survey radio survey.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/5bbad4e8760172bca106dda177f3a8381902c911

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Citations in the corpus

WMAP constraints on low redshift evolution of dark energy (2004, background): “Perturbations in dark energy also lead to observable signatures, though these can easily be confused with other physical effects (Caldwell, Dave & Steinhardt 1998; Weller & Lewis 2003; Bean & Doré 2004).”
Using the Full Power of the Cosmic Microwave Background to Probe Axion Dark Matter (2017, background): “(18) Equivalent expressions for scalar-field variables are given in Weller & Lewis (2003); Bean & Doré (2004).”
Spherical collapse in quintessence models with zero speed of sound (2009, background): “In particular, they have studied the different impact of quintessence with cs = 1 or cs = 0 on the cosmic microwave background [8, 9, 10, 11], galaxy redshift surveys [12], large neutral hydrogen surveys [13], or on the cross-correlation of the integrated Sachs-Wolfe effect in the cosmic microwave b”
Observational probes of cosmic acceleration (2012, background): “…much smaller than c allow fluctuations to grow on sub-horizon scales (e.g., Hu 1998; Erickson et al. 2002; Weller and Lewis 2003; DeDeo et al. 2003; Bean and Doré 2004). de Putter et al. (2010) provide a clear discussion of the background physics and observable consequences of dark energy…”
Cosmology and Fundamental Physics with the Euclid Satellite (2012, unknown): “We find that the pressure perturbation is given by [462, 150, 289] δp = ĉ(2)sδρ+ 3aH (a) ( ĉ(2)s − c(2)a ) ρ̄ V k2 .”
The effective theory of quintessence: the w < 1 side unveiled (2008, background): “The effect of a clustering quintessence can be measured with the cosmic microwave background [22, 23, 24, 25], galaxy redshift surveys [26], large neutral hydrogen surveys [27], or by cross-correlating the integrated Sachs-Wolfe effect in the cosmic microwave background with large scale structures [”