Annu. Rev.
Astron. Astrophys. 2002. 40:539-577.
THE EVOLUTION OF X-RAY CLUSTERS OF GALAXIES
Piero Rosati,1,3 Stefano Borgani,2 and Colin Norman3,4
1European Southern Observatory, D-85748 Garching
bei München, Germany; email: prosati@eso.org
2Dipartimento di Astronomia dell'Università
di Trieste, via Tiepolo 11, I-34131 Trieste, Italy; email: borgani@ts.astro.it
3Department of Physics and Astronomy, The
Johns Hopkins University, Baltimore, Maryland 21218; email: norman@stsci.edu
4Space Telescope Science Institute, Baltimore,
Maryland 21218
KEY WORDS: cosmology, intracluster medium, temperature,
masses, dark matter
Considerable progress has been made over the past 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 intracluster 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 intracluster gas are
significantly affected by nongravitational processes including
star formation and Active Galactic Nuclei (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.
Copyright
© 2002 by Annual
Reviews.
Last update: September 1, 2002
