Prog. Theor. Phys. Supplement No.169 (2007) pp. 109-112
Hard X-Ray Investigation of the Galactic Center Region with Suzaku
1ISAS/JAXA, Sagamihara 229-8510, Japan
2Department of Physics, University of Tokyo, Tokyo 113-0033, Japan
3Cosmic-ray Laboratory, RIKEN, Wako 351-0198, Japan
4Physics Department, Kyoto University, Kyoto 606-8502, Japan
5Faculty of Humanities and Socian Science, Iwate University,
Morioka 020-8550, Japan
6Department of Physical Science, Hiroshima University,
Higashi-Hiroshima 739-8426, Japan
7Max-Planck-Institute fur extraterrestrische Physik, 1312,
8Stanford Linear Accelerator Center, CA94025, USA
The Galactic center (GC) region has been known to exhibit
strong enhancements of hot diffuse plasma, which is characterized
by the highly ionized Fe-K fluorescence line.
Based on past X-ray observations with Ginga, ASCA, and RXTE, in the
Galactic plane or bulge region, a non-thermal emission, so-called
the “hard-tail", has been confirmed to dominate the hard X-ray flux
above 10 keV, and an association was found
between surface brightnesses of the thermal and non-thermal components despite
the completely different emission mechanism.
Therefore, it is obviously important to investigate an existence of
the hard-tail at GC with the unprecedented sensitivity of the HXD
By combining its narrow field-of-view of 30' and X-ray images simultaneously
obtained by the XIS below 10 keV, an extensive investigation of spectral and
spatial properties of the GC hard X-ray emission can be for the first
time realized. We will report on results from seven pointings around
GC, with a total exposure
of 300 ks, performed in the performance verification phase of Suzaku.
Strong hard X-ray signals were clearly detected in every observation
by HXD-PIN in 10–70 keV range with a few tenth mCrab level intensities.
DOI : 10.1143/PTPS.169.109
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