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银河系中心扩展/弥散硬X射线辐射的朱雀探测

Suzaku Detection of Extended/Diffuse Hard X-Ray Emission from the Galactic Center

Takayuki Yuasa, Ken-ichi Tamura, Kazuhiro Nakazawa, Motohide Kokubun, Kazuo Makishima, Aya Bamba, Yoshitomo Maeda, Tadayuki Takahashi, Ken Ebisawa, Atsushi Send… 展开作者

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

摘要:

朱雀号上的硬X射线探测器(HXD)和X射线成像光谱仪(XIS)观测到了银河系中心± 0.8度范围内的五个平面区域。从所有地区,显着的硬X射线发射检测HXD-PIN高达40千电子伏,除了扩展的等离子体发射,这是占主导地位的XIS带。硬X射线信号被推断为主要来自空间扩展的源,而不是来自少量明亮的离散物体。利用朱雀和其他卫星提供的信息,对HXD数据中来自编目X射线源(通常比1 mCrab亮)的贡献进行了估计和删除。即使在这种去除之后,硬X射线信号仍然很明显,表现出典型的12- 40 keV表面亮度为4 E-10 erg cm-2 s-1 deg-2和光子指数为1.8的幂律类光谱。XIS和HXD-PIN光谱的组合拟合证实了一个单独的硬尾分量叠加在热的热发射上,证实了先前基于XIS数据的报告。在5- 40 keV波段,硬尾在光谱上近似于光子指数~2的幂律,但更好的是那些有点凸的形状。扩展的硬X射线发射的可能起源进行了讨论。

英文摘要:

Five on-plane regions within +/- 0.8deg of the Galactic center were observed with the Hard X-ray Detector (HXD) and the X-ray Imaging Spectrometer (XIS) onboard Suzaku. From all regions, significant hard X-ray emission was detected with HXD-PIN up to 40 keV, 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 1 mCrab, 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--40 keV surface brightness of 4E-10 erg cm-2 s-1 deg-2 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--40 keV 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.

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