X-ray properties of clusters of galaxies

X-ray properties of ASCA observed 150 clusters of galaxies

The results of analyses for 150 clusters and groups of galaxies (z = 0.004-0.55) observed with ASCA are presented. These targets are classified as binary galaxies, group of galaxies, poor clusters of galaxies, rich clusters of galaxies, based on the number of member galaxies. All of these systems are thought to be bounded gravitationally.

These data was systematically analyzed with same way to reveal common properties and obtained following physical parameters; X-ray luminosity (10^40-46 h₅₀^-2ergs/s), flux-weighted temperature (0.7-12 keV), iron abundance (0.07-0.6 solar), X-ray morphological parameters like core radius Rc(< 300 kpc) and β (0.3-0.9), the gas mass, total iron mass and gravitational mass. Results were also compared with the optical properties taken from the literature, velocity dispersion, galaxy number density, galaxy mass, and optical morphological parameters. Based on these results, we investigate the origin of heavy elements, distribution of dark matter and evolution of clusters of galaxies.

Here, I show 2 figures which show the relation of Luminosity(of 2-10keV energy band) and redshift or Cluster Gas Temperature and one figure that shows the relation of virial mass M200 (The dark matter mass within the radius whose density is 200 times larger than the critical density) and characteristic density δc (ref. Navarro-Frenk-White (NFW) model).

Lx vs Z

This figure shows that the observed targets have various luminosities ranging 6 orders. We can not detect faint sources whose fluxes are lower than the detection limit of ASCA, shown in this figure. Lx vs kT

This figure shows that the observed targets have various temperatures. Temperature indicates the gravitational potential of system. On the other hand, X-ray luminosity indicates the gas mass M200 vs δc

83 bright targets are selected. The relation of these parameters reconstracted by power-law ralation indicates all galaxy groups are self-similar. According to NFW mode, the δc is proportional to (z_f + 1)². Therefore, the system of small mass is a old system, and the system of large mass is a new system.

references
S. Sato, F. Akimoto, A. Furuzawa, Y. Tawara, M. Watanabe, Y. Kumai,
Astrophys. J. 537, L73.(2000)
"THE OBSERVED MASS PROFILES OF DARK HALOS AND THE FORMATION EPOCH OF GALAXIES" Abstract, PDF