Open AccessMeasuring Ω 0 from the entropy evolution of clusters
Author(s) -
Kay Scott T.,
Bower Richard G.
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02745.x
Subject(s) - physics , astrophysics , cosmology , intracluster medium , statistical physics , galaxy cluster , dark matter , spectral density , entropy (arrow of time) , galaxy , statistics , quantum mechanics , mathematics
In this paper we have extended the entropy‐driven model of cluster evolution developed by Bower in order to be able to predict the evolution of galaxy clusters for a range of cosmological scenarios. We have applied this model to recent measurements of the evolution of the L x − T normalization and X‐ray luminosity function in order to place constraints on cosmological parameters. We find that these measurements alone do not select a particular cosmological framework. An additional constraint is required on the effective slope of the power spectrum to break the degeneracy that exists between this and the background cosmology. We therefore include a theoretical calculation of the Ω 0 dependence on the power spectrum, based on the cold dark matter paradigm, which infers Ω 0 <0.55 (0.1<Ω 0 <0.7 for Ω 0 +Λ 0 =1), at the 95 per cent confidence level. Alternatively, an independent measurement of the slope of the power spectrum from galaxy clustering requires Ω 0 <0.6 (Ω 0 <0.65 for Ω 0 +Λ 0 =1), again to 95 per cent confidence. The rate of entropy evolution is insensitive to the values of Ω 0 considered, although it is sensitive to changes in the distribution of the intracluster medium.