Suzaku observation of two ultraluminous X-ray sources in NGC1313

Tsunefumi Mizuno, Ryohei Miyawaki, Ken Ebisawa, Aya Kubota, Masao Miyamoto, Lisa Winter, Yoshihiro Ueda, Naoki Isobe, Kazuo Makishima

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Abstract

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 40erg 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 1.2-1.3 keV, 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.

Original languageEnglish
Pages (from-to)229-233
Number of pages5
JournalProgress of Theoretical Physics Supplement
Issue number169
Publication statusPublished - 2007
Externally publishedYes

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x rays
XMM-Newton telescope
newton
luminosity
curvature
radii
temperature
energy

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Mizuno, T., Miyawaki, R., Ebisawa, K., Kubota, A., Miyamoto, M., Winter, L., ... Makishima, K. (2007). Suzaku observation of two ultraluminous X-ray sources in NGC1313. Progress of Theoretical Physics Supplement, (169), 229-233.

Suzaku observation of two ultraluminous X-ray sources in NGC1313. / Mizuno, Tsunefumi; Miyawaki, Ryohei; Ebisawa, Ken; Kubota, Aya; Miyamoto, Masao; Winter, Lisa; Ueda, Yoshihiro; Isobe, Naoki; Makishima, Kazuo.

In: Progress of Theoretical Physics Supplement, No. 169, 2007, p. 229-233.

Research output: Contribution to journalArticle

Mizuno, T, Miyawaki, R, Ebisawa, K, Kubota, A, Miyamoto, M, Winter, L, Ueda, Y, Isobe, N & Makishima, K 2007, 'Suzaku observation of two ultraluminous X-ray sources in NGC1313', Progress of Theoretical Physics Supplement, no. 169, pp. 229-233.
Mizuno T, Miyawaki R, Ebisawa K, Kubota A, Miyamoto M, Winter L et al. Suzaku observation of two ultraluminous X-ray sources in NGC1313. Progress of Theoretical Physics Supplement. 2007;(169):229-233.
Mizuno, Tsunefumi ; Miyawaki, Ryohei ; Ebisawa, Ken ; Kubota, Aya ; Miyamoto, Masao ; Winter, Lisa ; Ueda, Yoshihiro ; Isobe, Naoki ; Makishima, Kazuo. / Suzaku observation of two ultraluminous X-ray sources in NGC1313. In: Progress of Theoretical Physics Supplement. 2007 ; No. 169. pp. 229-233.
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AU - Winter, Lisa

AU - Ueda, Yoshihiro

AU - Isobe, Naoki

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