Extremely Hot Gas in the Most X-ray Luminous Cluster RXJ1347

The 3rd Suzaku international Conference "Energetic Cosmos : from Suzaku to ASTRO-H" (June 29-July 2, 2009. Grand Park Otaru Hotel), Otaru, Hokkaido Japan
We present the results from long Suzaku observations of the most X-ray luminous galaxy cluster, RX J1347.5-1145 at z = 0.451. To understand the gas physics of a violent, cluster merger, we study physical properties of the hot (approximately 20 keV) gas clump in the south-east region discovered previously by Sunyaev-Zel'dovich (SZ) effect observations. With the joint analysis of the Suzaku and Chandra data, we determine the temperature of the hot gas in the south-east region to be 25.3(sup +6.1)(sub -4.5) (statistical; 90 % confidence level) (sup +6.9)(sub -9.5) (systematic; 90% confidence level) keV, which is in an excellent agreement with the previous joint analysis of the SZ effect in radio and the Chandra X-ray data. This is the first time that the X-ray spectroscopic observations alone have enabled a good measurement of such a high temperature gas component, because of Suzaku's unprecedented sensitivity over the wide X-ray band. These results indicate strongly that RX J1347.5-1145 has undergone a recent, violent merger. The spectral analysis shows that the SE component is consistent with being thermal. Therefore the present result confirms the presence of the hottest thermal gas in the Universe. On the other hand, no significant non-thermal hard X-ray emission is detected and we measure the 3sigma upper limit to the non-thermal flux in the 12-60 keV band, F > 8 x 10(exp -12)erg s(exp -1)cm(exp -2). Combining this limit with the synchrotron flux of a radio mini halo in this cluster, we find a lower limit to the strength of the cluster magnetic field, such that B > 0.007 micro G.
Meeting sponsors: The University of Tokyo, The Institute of Physical and Chemical Research, The Japan Society for the Promotion of Science
資料番号: AA0064574028
レポート番号: JAXA-SP-09-008E