著者

Tamagawa Toru Hayato Asami Nakamura Satoshi TERADA Yukikatsu BAMBA Aya HIRAGA Junko S. HUGHES John P. HWANG Una KATAOKA Jun KINUGASA Kenzo KUNIEDA Hideyo TANAKA Takaaki TSUNEMI Hiroshi UENO Masaru HOLT Stephen S. KOKUBUN Motohide MIYATA Emi SZYMKOWIAK Andrew TAKAHASHI Tadayuki TAMURA Keisuke UENO Daisuke MAKISHIMA Kazuo

出版者

社団法人日本天文学会

雑誌

PASJ : publications of the Astronomical Society of Japan (ISSN:00046264)

巻号頁・発行日

vol.61, no.1, pp.S167-S174, 2009-01-30

---

Tycho's supernova remnant was observed by the XIS and HXD instruments onboard the Suzaku satellite on 2006 June 26-29 for 92 ks. The spectrum up to 30 keV was well fitted with a two-component model, consisting of a power-law with photon index of 2.7 and a thermal bremsstrahlung model with temperature of 4.7 keV. The former component can alternatively be modeled as synchrotron emission from a population of relativistic electrons with an estimated roll-off energy of around 1 keV. In the XIS spectra, in addition to the prominent Fe K_alpha line (6.445 keV), we observe for the first time significant K_alpha line emission from the trace species Cr and Mn at energies of 5.48 keV and 5.95 keV, respectively. Faint K_beta lines from Ca (4.56 keV) and Fe (7.11 keV) are also seen. The ionization states of Cr and Mn, based on their line centroids, are estimated to be similar to that of Fe K_alpha (Fe XV or XVI).

著者

Totani Tomonori

出版者

Astronomical Society of Japan

雑誌

PASJ : publications of the Astronomical Society of Japan (ISSN:00046264)

巻号頁・発行日

vol.62, no.1, pp.L1-L4, 2010-02-25

参考文献数

43

著者

Hasegawa Ichiro

出版者

Astronomical Society of Japan

雑誌

PASJ : publications of the Astronomical Society of Japan (ISSN:00046264)

巻号頁・発行日

vol.54, no.6, pp.1091-1099, 2002-12-25

参考文献数

16

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

Fukue Jun Matsumoto Katsura

出版者

Astronomical Society of Japan

雑誌

PASJ : publications of the Astronomical Society of Japan (ISSN:00046264)

巻号頁・発行日

vol.53, no.1, pp.111-117, 2001-02-25

---

In supersoft X-ray sources the mass accretion rate is roughly equal to the Eddington rate, and traditional standard###disks cannot be adequate. We thus propose a supercritical accretion disk (superdisk) for supersoft X-ray sources.We have found that superdisks exhibit various distinct features, compared with standard thin disks. The continuous spectra of superdisks generally become flat (vS_v ~ v^0), which are greatly different from those of disk-blackbody spectra, as expected in the usual accretion disk systems. This flat nature is not so prominent in supersoft X-ray sources, compared with that in the superdisk around a black hole, since the radial extension of the disk is much smaller. Moreover, irradiation becomes important for a smaller accretion rate system. The superdisk picture was applied to RX J0019.8+2156, and reproduced its spectra and optical light curves well.

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.