Core Structure of Intracluster Gas: Effects of Radiative Cooling on Core Sizes

Abstract

We investigate the core structure of radiatively cooling intracluster gas, using a hydrodynamics code. We calculate evolution of model clusters of the initial core radii 160--300 kpc until the initial central cooling time, and analyze the resultant clusters using the double beta-model as done by observational studies. It is found that the core-size distribution thus obtained shows two peaks \sim 30--100 kpc and \sim 100--300 kpc and marginally can reproduce the observed distribution which exhibits two distinct peaks around \sim 50 kpc and \sim 200 kpc. This result may suggest radiative-cooling origin for small cores, while cooling is yet insignificant in the clusters of large cores. It should be noted that the small core peak is reproduced by clusters that are still keeping quasi-hydrostatic balance before the initial central cooling time has elapsed.