Copyright © 2002 by Annual Reviews. All rights reserved
|
| Annu. Rev. Astron. Astrophys. 2002. 40:
539-577 Copyright © 2002 by Annual Reviews. All rights reserved |
Reprinted with kind permission from Annual Reviews, 4139 El Camino Way, Palo Alto, California, USA
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Abstract. Considerable progress has been made over the last
decade in the study of the evolutionary trends of the population of
galaxy clusters in
the Universe. In this review we focus on observations in the X-ray
band. X-ray surveys with the ROSAT satellite, supplemented by
follow-up studies with ASCA and Beppo-SAX, have allowed
an assessment of the evolution of the space density of clusters out
to z 
1, and
the evolution of the physical properties of the
intra-cluster medium out to z
0.5.
With the advent of Chandra and Newton-XMM, and their
unprecedented sensitivity and angular resolution, these studies have
been extended beyond redshift unity and have revealed the complexity
of the thermodynamical structure of clusters. The properties of the
intra-cluster gas are significantly affected by non-gravitational
processes including star formation and Active Galactic Nucleus
(AGN) activity. Convincing
evidence has emerged for modest evolution of both the bulk of the
X-ray cluster population and their thermodynamical properties since
redshift unity. Such an observational scenario is consistent with
hierarchical models of structure formation in a flat low density
universe with
m
0.3 and
8
0.7 - 0.8 for the
normalization of the power spectrum. Basic methodologies for
construction of X-ray-selected cluster samples are reviewed and
implications of cluster evolution for cosmological models are discussed.
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