- 著者
- Koyama Katsuji Hyodo Yoshiaki Inui Tatsuya NAKAJIMA Hiroshi MATSUMOTO Hironori TSURU Takeshi Go TAKAHASHI Tadayuki MAEDA Yoshitomo YAMAZAKI Noriko Y. MURAKAMI Hiroshi YAMAUCHI Shigeo TSUBOI Yohko SENDA Atsushi KATAOKA Jun TAKAHASHI Hiromitsu HOLT Stephen S. BROWN Gregory V.
- 出版者
- 日本天文学会
- 雑誌
- PASJ : publications of the Astronomical Society of Japan (ISSN:00046264)
- 巻号頁・発行日
- vol.59, no.1, pp.S245-S255, 2007-01-31
- 被引用文献数
- 16 129
We have observed the diffuse X-ray emission from the Galactic Center (GC) using the X-ray Imaging Spectrometer (XIS) on Suzaku. The high-energy resolution and the low-background orbit provided excellent spectra of the GC diffuse X-rays (GCDX). The XIS found many emission lines in the GCDX near the energy of K-shell transitions of iron and nickel. The most pronounced features are Fe I Kα at 6.4 keV and K-shell absorption edge at 7.1 keV, which are from neutral and/or low ionization states of iron, and the K-shell lines at 6.7 keV and 6.9 keV from He-like (Fe XXV Kα) and hydrogenic (Fe XXVI Lyα) ions of iron. In addition, Kα lines from neutral or low ionization nickel (Ni I Kα) and He-like nickel (Ni XXVII Kα), Fe I Kβ, Fe XXV Kβ, Fe XXVI Lyβ, Fe XXV Kγ and FeXXVI Lyγ were detected for the first time. The line center energies and widths of Fe XXV Kα and Fe XXVI Lyα favor a collisional excitation plasma for the origin of the GCDX. The electron temperature determined from the line flux ratio of Fe XXV Kα/Fe XXV Kβ is similar to the ionization temperature determined from that of Fe XXV Kα/Fe XXVI Lyα. Thus it would appear that the GCDX plasma is close to ionization equilibrium. The 6.7 keV flux and temperature distribution to the galactic longitude is smooth and monotonic, in contrast to the integrated point source flux distribution. These facts support the hypothesis that the GCDX is truly diffuse emission rather than the integration of the outputs of a large number of unresolved point sources. In addition, our results demonstrate that the chemical composition of Fe in the interstellar gas near the GC is constrained to be about 3.5 times solar abundance.
- 著者
- Maeda Yoshitomo Ebara Masatoshi Fujimoto Ryuichi HAYASHI Takayuki INOUE Hirohiko ISHISAKI Yoshitaka MORI Hideyuki OKADA Shunsaku SUZUKI Kensuke UCHIYAMA Yasunobu SERLEMITSOS Peter J. SOONG Yang CHAN Kai-Wing OKAJIMA Takashi LEHAN John P. ITOH Kei ITOH Akiharu YOKOYAMA Yushi ITOH Yumi NAKAMURA Ryoko ISHIDA Manabu HAYAKAWA Akira INOUE Chiaki OKUMA Satoshi KUBOTA Ren SUZUKI Masaki OSAWA Takeyuki YAMASHITA Koujun KUNIEDA Hideyo TAWARA Yuzuru OGASAKA Yasushi FURUZAWA Akihiro TAMURA Keisuke SHIBATA Ryo HABA Yoshito NAITOU Masataka MISAKI Kazutami IIZUKA Ryo
- 出版者
- 一般社団法人日本物理学会
- 雑誌
- Progress of theoretical physics. Supplement (ISSN:03759687)
- 巻号頁・発行日
- no.169, pp.322-325, 2007-12-19
We present the in-flight performance of the X-ray telescopes (XRTs) onboard Suzaku. The imaging capability is significantly improved over the ASCA XRT, which had half-power diameters of 3'.6, to 1'.8-2'.3 for all four XRT-I modules. Contemporaneous fits of a power law to all the XIS spectra of the Crab Nebula taken at the two standard observing positions (XIS/HXD-default positions) gives a flux consistent with that obtained by Toor & Seward (1974) to within〜2%. The pre-collimator on the top of each XRT module successfully reduces the intensity of the stray light from the 20' and 50'-off directions down to the level of pre-flight expectations. We also present the thermal wobbling of the satellite. The wobbling causes the alignment error between the XRT-XIS system and the attitude and orbit control system. The wobbling of the alignment is as large as〜1arcmin. In the currently processed data, the absolute coordinate also has systematic uncertainty of up to〜1arcmin.