CLUSTER PHYSICS WITH DARK ENERGY

Abstract

Dark energy affects the abundance and evolution of clusters owing to their dependence on the geometry of the Universe and the power spectrum. Usually, there exits the degeneracy between σ8 and the matter energy density contrast [Formula: see text]. We avoid this by using the explicit dark energy dependent rms linear mass fluctuation σ8 which is consistent with the CMB normalization for general constant dark energy equation of state, ω Q . When we use the correct value of the critical density threshold δc = 1.58 into the cluster number density n calculation in the Press–Schechter (PS) formalism, PS formalism predicts the cluster number consistent with both simulation and observed data at the high mass region. The improved coefficients of Sheth–Tormen (ST) formalism by using the correct δc is also obtained. We found that changing ω Q by Δω Q = -0.1 from ω Q = -1.0 causes the changing of the comoving numbers of high mass clusters of M = 1016h-1M⊙ by about 20 and 40% at z = 0 and 1, respectively.