We have made a comparative study of morphological evolution in simulated DM
halos and X-ray brightness distribution, and in optical clusters. Samples of
simulated clusters include star formation with supernovae feedback, radiative
cooling, and simulation in the adiabatic limit at three different redshifts, z
= 0.0, 0.10, and 0.25. The optical sample contains 208 ACO clusters within
redshift, z≤0.25. Cluster morphology, within 0.5 and 1.0 h−1 Mpc
from cluster center, is quantified by multiplicity and ellipticity.
We find that the distribution of the dark matter halos in the adiabatic
simulation appear to be more elongated than the galaxy clusters. Radiative
cooling brings halo shapes in excellent agreement with observed clusters,
however, cooling along with feedback mechanism make the halos more flattened.
Our results indicate relatively stronger structural evolution and more clumpy
distributions in observed clusters than in the structure of simulated clusters,
and slower increase in simulated cluster shapes compared to those in the
observed one.
Within z≤0.1, we notice an interesting agreement in the shapes of
clusters obtained from the cooling simulations and observation. We also notice
that the different samples of observed clusters differ significantly in
morphological evolution with redshift. We highlight a few possibilities
responsible for the discrepancy in morphological evolution of simulated and
observed clusters.Comment: Accepted for publication in MNRAS, 2006; 15 pages, 13 postscript
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