Spherical Collapse Model And Dark Energy(I)

TL;DR

This paper investigates the spherical collapse model in cosmologies with dark energy that clusters synchronously with matter, revealing significant dependence of key parameters on dark energy's equation of state, and impacts on galaxy cluster formation.

Contribution

It introduces a model where dark energy clusters with matter on galaxy cluster scales, contrasting with previous assumptions, and explores its effects on cluster formation and evolution.

Findings

Key parameters depend non-trivially on dark energy equation of state.

Number density of galaxy clusters is exponentially affected by dark energy properties.

Cluster evolution shows significant sensitivity to dark energy clustering assumptions.

Abstract

In existing literatures about the top-hat spherical collapse model of galaxy clusters formation in cosmology containing dark energies, dark energies are usually assumed not to cluster on this scale. But all these literatures ignored the current describing the flowing of dark energies outside the clusters which should exist under this assumption, so the conclusions of these literatures are worth further explorations. In this paper we study this model in QCDM or Phantom-CDM cosmologies(flat) by assuming that dark energies will cluster synchronously with ordinary matters on the scale of galaxy clusters so the dark energy current flowing outside the clusters does not exist at all and find that in this case, the key parameters of the model exhibit rather non-trivial and remarkable dependence on the equation of state coefficients of dark energies. We then apply the results in Press-Scheter theory and calculate the number density of galaxy clusters and its evolutions. We find that this two quantities are both affected exponentially by the equation of state coefficients of dark energies. We leave the study of this model with the assumption that dark energies do not cluster on the scale of galaxy clusters at all as the topic of another paper where similar conclusions will be obtained also.