著者

Mizuno Tsunefumi Miyawaki Ryohei Ebisawa Ken KUBOTA Aya MIYAMOTO Masao WINTER Lisa UEDA Yoshihiro ISOBE Naoki MAKISHIMA Kazuo

出版者

Published for the Yukawa Institute for Theoretical Physics and the Physical Society of Japan

雑誌

Progress of theoretical physics. Supplement (ISSN:03759687)

巻号頁・発行日

no.169, pp.229-233, 2007-12-19

参考文献数

24

被引用文献数

1

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We report about the Suzaku observation of two ultraluminous X-ray sources (ULXs), X-1 and X-2, in NGC1313, together with their spectra by XMM-Newton. During the observation, both showed intensity-correlated spectral changes. The brighter source, X-1, exhibited the highest luminosity (~3×10^<40>erg s^<-1>) ever recorded from this source. Its spectral variation is ascribed to a strong power-law like component with a mild high energy curvature, while about 10% of the flux is carried by a stable soft component modeled by a cool disk emission. These properties suggest that the source was in the "very high" state, wherein the disk emission is strongly Comptonized and the optically-thick disk is truncated at a large radii or cooled off. The spectrum of X-2 is best represented, in its fainter phase, by a multicolor disk model with the innermost disk temperature of 1.2-1.3keV, and becomes flatter as the source gets brighter. Hence X-2 is interpreted to be in a slim disk state. These results suggest that the two ULXs host black holes of a few tens to a few hundreds solar masses.