Confronting the sound speed of dark energy with future cluster surveys

Abstract

Future cluster surveys will observe galaxy clusters numbering in the hundred thousands. We consider this work how these surveys can be used to constrain dark energy parameters: in particular, the equation of state parameter w and the non-adiabatic sound speed c_s^2. We demonstrate that, in combination with Cosmic Microwave Background (CMB) observations from Planck, cluster surveys such as that in the ESA Euclid project will be able to determine a time-independent w with subpercent precision. Likewise, if the dark energy sound horizon falls within the length scales probed by the cluster survey, then c_s^2 can be pinned down to within an order of magnitude. In the course of this work, we also investigate the process of dark energy virialisation in the presence of an arbitrary sound speed. We find that dark energy clustering and virialisation can lead to dark energy contributing to the total cluster mass at approximately the 0.1% level at maximum.

24 pages, 7 figures, prepared for submission to JCAP

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Cited by in corpus (7)

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• Full Investigation on the Dynamics of Power-Law Kinetic Quintessence
• A short review on clustering dark energy
• Effects of tidal gravitational fields in clustering dark energy models
• Spherical collapse of non-top-hat profiles in the presence of dark energy with arbitrary sound speed
• Tidal virialization of dark matter haloes with clustering dark energy
• On the virialization threshold for halo mass functions