Abstract We present an observational approach to constrain the global structure and evolution of the intracluster medium utilizing the ROSAT and ASCA distant cluster sample. From statistical analysis of the gas density profile and the connection to the L_{X}-T relation under the β-model, the scaled gas profile is found to be nearly universal for the outer region. On the other hand, a large density scatter exists in the core region and there is clearly a deviation from the self-similar scaling for clusters with a small core. The discovery of the existence of an X-ray fundamental plane in the distant cluster sample suggests that the cooling time (t_{cool}) is a parameter to control the gas structure. The appearance of small cores in regular clusters may be strongly connected with the thermal evolution. We derive the luminosity-ambient temperature (T') relation, assuming the universal temperature profile for the clusters with short t_{ cool}, and find the dispersion around the relation significantly decreases and the slope becomes marginally less steep. Considering a correlation between t_{cool} and the X-ray morphology, the observational results lead us to draw a phenomenological picture: after a cluster collapses and t_{cool} falls below the age of the universe, the core cools radiatively with quasi-hydrostatic balancing in the gravitational potential, and the central density gradually becomes higher to evolve from an outer-core-dominant cluster, which follows the self-similarity, to inner-core-dominant cluster.

Keywords galaxies: clusters: general X-rays: galaxies: clusters

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