• Hyodo, Yoshiaki
• Takahashi, Tadayuki
• Nakazawa, Kazuhiro
• Tamura, Ken-Ichi
• Bamba, Aya
• Maeda, Yoshitomo
• Yuasa, Takayuki
• Koyama, Katsuji
• Takahashi, Hiromitsu
• Yamauchi, Shigeo
• Senda, Atsushi
• Ebisawa, Ken
• Makishima, Kazuo
• Tsuru, Takeshi Go
• Kokubun, Motohide

Abstract

Five on-plane regions within ±0°.8 of the galactic center were observed with the Hard X-ray Detector (HXD) and the X-ray Imaging Spectrometer (XIS) aboard Suzaku. From all regions, significant hard X-ray emission was detected with HXD-PIN up to 40keV, in addition to the extended plasma emission which is dominant in the XIS band. The hard X-ray signals are inferred to come primarily from a spatially extended source, rather than from a small number of bright discrete objects. Contributions to the HXD data from catalogued X-ray sources, typically brighter than 1mCrab, were estimated and removed using information from Suzaku and other satellites. Even after this removal, the hard X-ray signals remained significant, exhibiting a typical 12-40keV surface brightness of 4×10<SUP>-10</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP> deg<SUP>-2</SUP> and power-law-like spectra with a photon index of 1.8. Combined fittings to the XIS and HXD-PIN spectra confirm that a separate hard tail component is superposed onto the hot thermal emission, confirming a previous report based on the XIS data. Over the 5--40keV band, the hard tail is spectrally approximated by a power law of photon index ̃2, but better by those with somewhat convex shapes. Possible origins of the extended hard X-ray emission are discussed....

Topics

• impedance spectroscopy
• surface