- 著者
- Mizuno Tsunefumi Miyawaki Ryohei Ebisawa Ken KUBOTA Aya MIYAMOTO Masao WINTER Lisa M. UEDA Yoshihiro ISOBE Naoki DEWANGAN Gulab C. DONE Chris GRIFFITHS Richard E. HABA Yoshito KOKUBUN Motohide KOTOKU Jun'ichi MAKISHIMA Kazuo MATSUSHITA Kyoko MUSHOTZKY Richard F. NAMIKI Masaaki PETRE Robert TAKAHASHI Hiromitsu TAMAGAWA Toru TERASHIMA Yuichi
- 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.S257-S267, 2007-01-31
- 参考文献数
- 56
- 被引用文献数
- 2
Two ultraluminous X-ray sources (ULXs) in the nearby Sb galaxy NGC 1313, named X-1 and X-2, were observed with Suzaku on 2005 September 15. During the observation for a net exposure of 28 ks (but over a gross time span of 90 ks), both objects varied in intensity by about 50%. The 0.4–10 keV X-ray luminosities of X-1 and X-2 were measured as 2.5×1040 ergs-1 and 5.8×1039 ergs-1, respectively, with the former exhibiting the highest ever reported for this ULX. The spectrum of X-1 can be explained by the sum of a strong and variable powerlaw component with a high-energy cutoff, and a stable multicolor blackbody with an innermost disk temperature of ∼ 0.2keV. These results suggest that X-1 was in a "very high" state, where disk emission is strongly Comptonized. The absorber within NGC 1313 toward X-1 is suggested to have a subsolar oxygen abundance. The spectrum of X-2 is best represented, in its fainter phase, by a multicolor blackbody model with an innermost disk temperature of 1.2–1.3 keV, and becomes flatter as the source becomes brighter. Hence, X-2 is interpreted to be in a slim-disk state. These results suggest that the two ULXs have black hole masses of some dozens to a few hundred of solar masses.
- 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.