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arXiv · 0805.0500

Suzaku broad-band spectroscopy of RX J1347.5-1145: constraints on the extremely hot gas and non-thermal emission

N. Ota·K. Murase·T. Kitayama·E. Komatsu·M. Hattori·H. Matsuo·T. Oshima·Y. Suto·K. Yoshikawa
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Abstract

We present the results from the analysis of long Suzaku observations of the most X-ray luminous galaxy cluster RX J1347.5-1145 at z=0.451. Aims: We study physical properties of the hot (~20 keV) gas clump in the south-east (SE) region discovered by the Sunyaev-Zel'dovich (SZ) effect observations, to understand the gas physics of a violent cluster merger. We also explore a signature of non-thermal emission using the hard X-ray data. Results: We find that the single-temperature model fails to reproduce the continuum emission and Fe-K lines measured by XIS simultaneously. The two-temperature model with a very hot component improves the fit, although the XIS data can only give a lower bound on its temperature. We detect the hard X-ray emission in the 12-40 keV band at the 7 sigma level; however, the significance becomes marginal when the systematic error in the background estimation is included. With the Suzaku + Chandra joint analysis, we determine the temperature of the SE excess component to be 25.3^{+6.1}_{-4.5} ^{+6.9}_{-9.5} keV (90% statistical and systematic errors), which is in an excellent agreement with the previous SZ + X-ray analysis. This is the first time that the X-ray spectroscopy alone gives a good measurement of the temperature of the hot component in the SE region, which is made possible by Suzaku's unprecedented sensitivity to the wide X-ray band. These results strongly indicate that the cluster has undergone a recent, violent merger. The spectral analysis shows that the SE component is consistent with being thermal. We find the 3 sigma upper limit on the non-thermal flux, F < 8e-12 erg s^{-1} cm^{-2} in the 12-60 keV band. Combining this limit with a recent discovery of the radio mini halo at 1.4 GHz, we find a lower limit on the strength of the intracluster magnetic field, B > 0.007 micro G.

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N. Ota, K. Murase, T. Kitayama, E. Komatsu, M. Hattori, H. Matsuo, T. Oshima, Y. Suto, K. Yoshikawa. 2008-09-01. Suzaku broad-band spectroscopy of RX J1347.5-1145: constraints on the extremely hot gas and non-thermal emission. https://doi.org/10.1051/0004-6361%3A200810122

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