A Morphology - cosmology connection for x-ray clusters

Oct 5, 1993
8 pages
Published in:
  • Astrophys.J.Lett. 419 (1993) L9
e-Print:
Report number:
  • CFA-3709

Citations per year

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Abstract: (arXiv)
We employ N--body/3D3D gas dynamic simulations of the formation of galaxy clusters to determine whether cluster X--ray morphologies can be used as cosmological constraints. Confirming the analytic expectations of Richstone, Loeb, \& Turner, we demonstrate that cluster evolution is sensitive to the cosmological model in which the clusters form. We further show that evolutionary differences are echoed in the gross morphological features of the cluster X--ray emission. We examine current--epoch X--ray images of models originating from the same initial density fields evolved in three different cosmologies: (i) an unbiased, low density universe with \Omega_o \se 0.2; (ii) an unbiased universe dominated by vacuum energy with \Omega_o \se 0.2 and \lambda_o \se 0.8 and (iii) a biased Einstein--deSitter model (\Omega \se 1, σ8=0.59\sigma_8=0.59). Using measures of X--ray morphology such as the axial ratio and centroid shifting, we demonstrate that clusters evolved in the two low Ωo\Omega_o models are much more regular, spherically symmetric, and centrally condensed than clusters evolved in the Einstein--deSitter model. This morphology--cosmology connection, along with the availability of a large body of cluster X--ray observations, makes cluster X--ray morphology both a powerful and a practical cosmological discriminant.