Ozawa, Midori, Koyama, Katsuji, Yamaguchi, Hiroya, Masai, Kuniaki, Tamagawa, Toru
We present a hard X-ray spectrum of unprecedented quality of the Galactic supernova remnant W49B obtained with the Suzaku satellite. The spectrum exhibits an unusual structure consisting of a...
Yamaguchi, Hiroya, Ozawa, Midori, Koyama, Katsuji, Masai, Kuniaki, Hiraga, Junko S., Ozaki, Masanobu, ...
We present the Suzaku spectroscopic study of the Galactic middle-aged supernova remnant (SNR) IC 443. The X-ray spectrum in the 1.75-6.0 keV band is described by an optically-thin thermal plasma with...
A Super Bubble Candidate in the Galactic Center and a Local Enhancement G359.77-0.09 (2009)
Mori, Hideyuki, Hyodo, Yoshiaki, Tsuru, Takeshi Go, Nobukawa, Masayoshi, Koyama, Katsuji
A 20' \times 16' elliptical ring-like structure has been found near the Galactic center in the narrow energy band corresponding to the K$\alpha$ line from He-like sulfur. In the ring, two diffuse...
An X-Ray Face-on View of the Sgr B Molecular Clouds Observed with Suzaku (2009)
Ryu, Syukyo G., Koyama, Katsuji, Nobukawa, Masayoshi, Fukuoka, Ryosuke, Tsuru, Takeshi Go
We present a new methodology to derive the positions of the Sgr B molecular clouds (MCs) along the line of sight, as an application study of the Galactic center diffuse X-rays (GCDX). The GCDX is...
A New Supernova Remnant Candidate and an Associated Outflow in the Sagittarius C Region (2009)
Tsuru, Takeshi Go, Nobukawa, Masayoshi, Nakajima, Hiroshi, Matsumoto, Hironori, Koyama, Katsuji, Yamauchi, Shigeo
We present the Suzaku results on a new candidate of a supernova remnant (SNR) in the Sagittarius C region. We detected diffuse X-rays of an elliptical shape (G359.41-0.12) and a chimney-like...
Iron emission lines on the galactic ridge observed with Suzaku (2009)
Yamauchi, Shigeo, Ebisawa, Ken, Tanaka, Yasuo, Koyama, Katsuji, Matsumoto, Hironori, Yamasaki, Noriko Y., ...
Nakajima, Hiroshi, Tsuru, Takeshi Go, Nobukawa, Masayoshi, Matsumoto, Hironori, Koyama, Katsuji, Murakami, Hiroshi, ...
This paper reports on the first results of the Suzaku observation in the Sgr C region. We detected four diffuse clumps with strong line emission at 6.4keV, Ka from neutral or low-ionized Fe. One of...
Uchiyama, Hideki, Ozawa, Midori, Matsumoto, Hironori, Tsuru, Takeshi Go, Koyama, Katsuji, Kimura, Masashi, ...
The charge transfer inefficiency (CTI) of the X-ray CCDs on board the Suzaku satellite (X-ray Imaging Spectrometers; XIS) has increased since the launch due to radiation damage, and the energy...
Iron Emission Lines on the Galactic Ridge Observed with Suzaku (2008)
Yamauchi, Shigeo, Ebisawa, Ken, Tanaka, Yasuo, Koyama, Katsuji, Matsumoto, Hironori, Yamasaki, Noriko Y., ...
In order to elucidate origin of the Galactic Ridge X-ray Emission, we analyzed Suzaku data taken at various regions along the Galactic plane and studied their Fe-K emission line features. Suzaku...
Ozawa, Midori, Uchiyama, Hideki, Matsumoto, Hironori, Nakajima, Hiroshi, Koyama, Katsuji, Tsuru, Takeshi Go, ...
The X-ray Imaging Spectrometer (XIS) on board the Suzaku satellite is an X-ray CCD camera system that has superior performance such as a low background, high quantum efficiency, and good energy...
Timing and Spectral Study of AX J1745.6-2901 with Suzaku (2008)
Hyodo, Yoshiaki, Ueda, Yoshihiro, Yuasa, Takayuki, Maeda, Yoshitomo, Makishima, Kazuo, Koyama, Katsuji
The eclipsing low-mass X-ray binary AX J1745.6-2901 was observed with Suzaku in its outburst phase. Combining the Chandra observation made 1.5 month earlier than Suzaku, we determined the orbital...
Suzaku Observation of 30Dor C: A Supernova Remnant with the Largest Non-Thermal Shell (2008)
Yamaguchi, Hiroya, Bamba, Aya, Koyama, Katsuji
This paper reports on the Suzaku results of thermal and non-thermal features of 30 Dor C, a supernova remnant (SNR) in a superbubble of the Large Magellanic Cloud (LMC). The west rim exhibits a...
Nobukawa, Masayoshi, Koyama, Katsuji, Matsumoto, Hironori, Tsuru, Takeshi Go
SAX J1748.2$-$2808 is a unique X-ray object with a flat spectrum and strong emission lines at 6.4--7.0 keV. The Suzaku satellite resolved the emission lines into 3 K-shell lines from neutral and...
X-Ray Emission from Supernova Remnants Observed in the ASCA Galactic Plane Survey (2008)
Yamauchi, Shigeo, Ueno, Masaru, Koyama, Katsuji, Bamba, Aya
X-ray images and spectra of 5 cataloged supernova remnants (SNRs), G12.0-0.1, G346.6-0.2, G348.5+0.1, G348.7+0.3, and G355.6-0.0, observed in the ASCA galactic plane survey are presented. The sizes...
X-Ray Observations of the Sagittarius D HII Region toward the Galactic Center with Suzaku (2008)
Sawada, Makoto, Tsujimoto, Masahiro, Koyama, Katsuji, Law, Casey J., Tsuru, Takeshi Go, Hyodo, Yoshiaki
We present a Suzaku X-ray study of the Sagittarius D (Sgr D) HII region in the Galactic center region. Two 18'x18' images by the X-ray Imaging Spectrometer (XIS) encompass the entire Sgr D complex....
Koyama, Katsuji, Takikawa, Yojiro, Hyodo, Yoshiaki, Inui, Tatsuya, Nobukawa, Masayoshi, Matsumoto, Hironori, ...
The high energy resolution and low background, particularly in the hard X-ray band, of the X-ray Imaging Spectrometer onboard Suzaku provide excellent spectra of the Galactic center diffuse X-rays...
Inui, Tatsuya, Koyama, Katsuji, Matsumoto, Hironori, Tsuru, Takeshi Go
We investigate long-term X-ray behaviors from the Sgr B2 complex using archival data of the X-ray satellites Suzaku, XMM-Newton, Chandra and ASCA. The observed region of the Sgr B2 complex includes...
Spectral study of the galactic ridge X-ray emission with Suzaku (2008)
Ebisawa, Ken, Yamauchi, Shigeo, Tanaka, Yasuo, Koyama, Katsuji, Ezoe, Yuichiro, Bamba, Aya, ...
Nobukawa, Masayoshi, Tsuru, Takeshi Go, Takikawa, Yojiro, Hyodo, Yoshiaki, Inui, Tatsuya, Nakajima, Hiroshi, ...
We made a 100 ks observation of the Sagittarius (Sgr) B1 region at (l, b) = (0.5, -0.1) near to the Galactic center (GC) with the Suzaku/XIS. Emission lines of S XV, Fe I, Fe XXV, and Fe XXVI were...
Matsumoto, Hironori, Uchiyama, Hideki, Sawada, Makoto, Tsuru, Takeshi G., Koyama, Katsuji, Katagiri, Hideaki, ...
We report the Suzaku results of HESS J1614-518, which is the brightest extended TeV gamma-ray source discovered in the Galactic plane survey conducted using the H.E.S.S. telescope. We discovered...
Suzaku X-Ray Spectroscopy of a Peculiar Hot Star in the Galactic Center Region (2007)
Hyodo, Yoshiaki, Tsujimoto, Masahiro, Koyama, Katsuji, Nishiyama, Shogo, Nagata, Tetsuya, Sakon, Itsuki, ...
We present the results of a Suzaku study of a bright point-like source in the 6.7 keV intensity map of the Galactic center region. We detected an intense FeXXV 6.7 keV line with an equivalent width...
Shiro Ueno, Katsuji Koyama, Hisamitsu Awaki, Ichizo Hayashi, Philip R. Blanco
We present the results of ASCA observations of the Seyfert galaxy Mkn 463. We find that the 1--10 keV X-ray spectrum consists of at least two components: soft and hard. We found no evidence for a...
A Time-Variable X-Ray Echo: Indications of a Past Flare of the Galactic-Center Black Hole (2007)
Koyama, Katsuji, Inui, Tatsuya, Matsumoto, Hironori, Tsuru, Takeshi Go
A time-variability study of the neutral iron line flux at 6.40keV in the Sgr B2 region from data of Suzaku and Chandra is presented. The highly ionized iron line at 6.68keV is due to Galactic Center...
Spectral Study of the Galactic Ridge X-ray Emission with Suzaku (2007)
Ebisawa, Ken, Yamauchi, Shigeo, Tanaka, Yasuo, Koyama, Katsuji, Ezoe, Yuichiro, Bamba, Aya, ...
We have observed a typical Galactic plane field at (l,b) = (28.46d, -0.20d) with Suzaku for 100 ksec to carry out a precise spectral study of the Galactic Ridge X-ray Emission (GRXE). The field is...
Suzaku Detection of an Intense X-Ray Flare from an A-type Star HD161084 (2007)
Miura, Junichiro, Tsujimoto, Masahiro, Tsuboi, Yohko, Maeda, Yoshitomo, Sugawara, Yasuharu, Koyama, Katsuji, ...
We report a serendipitous detection of an intense X-ray flare from the Tycho reference source HD 161084 during a Suzaku observation of the Galactic Center region for 20 ks. The X-ray Imaging...
Development of an n-channel CCD, CCD-NeXT1, for Soft X-ray Imager onboard the NeXT satellite (2007)
Takagi, Shin-ichiro, Tsuru, Takeshi Go, Inui, Tatsuya, Matsumoto, Hironori, Koyama, Katsuji, Ozawa, Hideki, ...
NeXT (New X-ray Telescope) is the next Japanese X-ray astronomical satellite mission after the Suzaku satellite. NeXT aims to perform wide band imaging spectroscopy. Due to the successful development...
The Suzaku Observation of RCW 86 Northeastern Shell (2007)
Yamaguchi, Hiroya, Koyama, Katsuji, Nakajima, Hiroshi, Bamba, Aya, Yamazaki, Ryo, Vink, Jacco, ...
This paper reports the Suzaku results on the northeast shell of RCW 86. With the spatial and spectral analysis, we separated the X-rays into three distinct components; low (kT_e~0.3keV) and high...
Suzaku Detection of Extended/Diffuse Hard X-Ray Emission from the Galactic Center (2007)
Yuasa, Takayuki, Tamura, Ken-ichi, Nakazawa, Kazuhiro, Kokubun, Motohide, Makishima, Kazuo, Bamba, Aya, ...
Five on-plane regions within +/- 0.8deg of the Galactic center were observed with the Hard X-ray Detector (HXD) and the X-ray Imaging Spectrometer (XIS) onboard Suzaku. From all regions, significant...
Takahashi, Tadayuki, Tanaka, Takaaki, Uchiyama, Yasunobu, Hiraga, Junko S., Nakazawa, Kazuhiro, Watanabe, Shin, ...
We report on results from Suzaku broadband X-ray observations of the southwest part of the Galactic supernova remnant (SNR) RX J1713.7-3946 with an energy coverage of 0.4-40 keV. The X-ray spectrum,...
Suzaku wide-band observations of SN 1006 (2007)
Bamba, Aya, Fukazawa, Yasushi, Hiraga, Junko S., Hughes, John P., Katagiri, Hideaki, Kokubun, Motohide, ...
We report on the wide band spectra of SN 1006 as observed by Suzaku. Thermal and nonthermal emission are successfully resolved thanks to the excellent spectral response of Suzaku's X-ray CCD XIS. The...
Suzaku Spectroscopy of the Extended X-Ray Emission in M17 (2007)
Hyodo, Yoshiaki, Tsujimoto, Masahiro, Hamaguchi, Kenji, Koyama, Katsuji, Kitamoto, Shunji, Maeda, Yoshitomo, ...
We present the results of a Suzaku spectroscopic study of the soft extended X-ray emission in the HII region M17. The spectrum of the extended emission was obtained with a high signal-to-noise ratio...
X-Ray Spectroscopy of SN 1006 with Suzaku (2007)
Yamaguchi, Hiroya, Koyama, Katsuji, Katsuda, Satoru, Nakajima, Hiroshi, Hughes, John P., Bamba, Aya, ...
We report on observations of SN 1006 with the X-ray Imaging Spectrometers (XIS) on board Suzaku. We firmly detected K-shell emission from Fe, for the first time, and find that the Fe ionization state...
Discovery of a new X-ray transient source in the Scutum region with Suzaku (2007)
Yamauchi, Shigeo, Ebisawa, Ken, Bamba, Aya, Ishida, Manabu, Iwasawa, Kazushi, Tanaka, Yasuo, ...
The X-ray observatory Suzaku (2007)
Mitsuda, Kazuhisa, Bautz, Mark, Inoue, Hajime, Kelley, Richard L., Koyama, Katsuji, Kunieda, Hideyo, ...
Hard X-ray investigation of the galactic center region with Suzaku (2007)
Kokubun, Motohide, Yuasa, Takayuki, Tamura, Ken-ichi, Makishima, Kazuo, Takahashi, Tadayuki, Nakazawa, Kazuhiro, ...
Suzaku spectral study of the galactic ridge X-ray emission (2007)
Ebisawa, Ken, Yamauchi, Shigeo, Tanaka, Yasuo, Koyama, Katsuji, Suzaku Team
A Suzaku Observation of the Low-Ionization Fe-Line Emission from RCW 86 (2006)
Ueno, Masaru, Sato, Rie, Kataoka, Jun, Bamba, Aya, Harrus, Ilana, Hiraga, Junko, ...
The newly operational X-ray satellite Suzaku observed the southwestern quadrant of the supernova remnant (SNR) RCW 86 in February 2006 to study the nature of the 6.4 keV emission line first detected...
Tsuru, Takeshi Go, Ozawa, Midori, Hyodo, Yoshiaki, Matsumoto, Hironori, Koyama, Katsuji, Awaki, Hisamitsu, ...
The extended X-ray emission from 'the Cap' region located 11' (11.6 kpc) above the disk of the starburst galaxy M82 has been observed with Suzaku and XMM-Newton. Owing to the good energy resolution...
Discoveries of Diffuse Iron Line Sources from the Sgr B Region (2006)
Koyama, Katsuji, Inui, Tatsuya, Hyodo, Yoshiaki, Matsumoto, Hironori, Tsuru, Takeshi Go, Maeda, Yoshitomo, ...
The radio complex Sgr B region is observed with the X-Ray Imaging Spectrometers (XIS) on board Suzaku. This region exhibits diffuse iron lines at 6.4, 6.7 and 6.9 keV, which are K$\alpha$ lines of Fe...
Iron and Nickel Line Diagnostics for the Galactic Center Diffuse Emission (2006)
Koyama, Katsuji, Hyodo, Yoshiaki, Inui, Tatsuya, Nakajima, Hiroshi, Matsumoto, Hironori, Tsuru, Takeshi Go, ...
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 provide...
New X-ray views of the Galactic center observed with Suzaku (2006)
Koyama, Katsuji, Hyodo, Yoshiaki, Inui, Tatsuya
We report the diffuse X-ray emissions from the Sgr A and B regions observed with Suzaku. From the Sgr A region, we found many K-shell transition lines of iron and nickel. The brightest are K alpha...
Suzaku Observations of HESS J1616-508: Evidence for a Dark Particle Accelerator (2006)
Matsumoto, Hironori, Ueno, Masaru, Bamba, Aya, Hyodo, Yoshiaki, Mori, Hideyuki, Uchiyama, Hideki, ...
We observed the bright unidentified TeV gamma-ray source HESS J1616-508 with the X-ray Imaging Spectrometers onboard the Suzaku satellite. No X-ray counterpart was found to a limiting flux of 3.1e-13...
Discovery of a possible X-ray counterpart to HESS J1804-216 (2006)
Bamba, Aya, Koyama, Katsuji, Hiraga, Junko S., Hughes, John P., Kohmura, Takayoshi, Kokubun, Motohide, ...
Suzaku deep observations have discovered two highly significant nonthermal X-ray sources, Suzaku J1804$-$2142 (Src 1) and Suzaku J1804$-$2140 (Src 2), positionally coincident with the unidentified...
A Detailed Observation of a LMC Supernova Remnant DEM L241 with XMM-Newton (2006)
Bamba, Aya, Ueno, Masaru, Nakajima, Hiroshi, Mori, Koji, Koyama, Katsuji
We report on an {\it XMM-Newton} observation of the supernova remnant (SNR) \object{DEM L241} in the Large Magellanic Cloud. In the soft band image, the emission shows an elongated structure, like a...
Chandra Observation of the Starburst Galaxy NGC 2146 (2004)
Inui, Tatsuya, Matsumoto, Hironori, Tsuru, Takeshi Go, Koyama, Katsuji, Matsushita, Satoki, Peck, Alison B., ...
We present six monitoring observations of the starburst galaxy NGC 2146 using the Chandra X-ray Observatory. We have detected 67 point sources in the 8'.7 x 8'.7 field of view of the ACIS-S detector....
Bamba, Aya, Yamazaki, Ryo, Yoshida, Tatsuo, Terasawa, Toshio, Koyama, Katsuji
The outer shells of young supernova remnants (SNRs) are the most plausible acceleration sites of high-energy electrons with the diffusive shock acceleration (DSA) mechanism. We studied spatial and...
Yamaguchi, Hiroya, Ueno, Masaru, Koyama, Katsuji, Bamba, Aya, Yamauchi, Shigeo
We report on XMM-Newton observations of G32.45+0.1 and G38.55+0.0. These were discovered as diffuse hard X-ray sources with the ASCA Galactic plane survey, but the limited spatial resolution of ASCA...
X-ray Study of the Intermediate-Mass Young Stars Herbig Ae/Be Stars (2004)
Hamaguchi, Kenji, Yamauchi, Shigeo, Koyama, Katsuji
We present the ASCA results of intermediate-mass pre-main-sequence stars (PMSs), or Herbig Ae/Be stars (HAeBes). Among the 35 ASCA pointed-sources, we detect 11 plausible X-ray counterparts. X-ray...
A Discovery of a Peculiar Pulsar in the Small Magellanic Cloud (2003)
Ueno, Masaru, Yamaguchi, Hiroya, Takagi, Shin-ichiro, Yokogawa, Jun, Koyama, Katsuji
We report on a peculiar X-ray binary pulsar IKT1 = RXJ0047.3-7312 observed with XMM-Newton in Oct. 2000. The X-ray spectrum is described by a two-component spectrum. The hard component has a broken...
Yamazaki, Ryo, Yoshida, Tatsuo, Terasawa, Toshio, Bamba, Aya, Koyama, Katsuji
Characteristic scale lengths of nonthermal X-rays from the SN1006 NE rim, which are observed by Chandra, are interpreted in the context of the diffusive shock acceleration on the assumption that the...
Thermal and Non-thermal X-Rays from the LMC Super Bubble 30 Dor C (2003)
Bamba, Aya, Ueno, Masaru, Nakajima, Hiroshi, Koyama, Katsuji
We report on the discovery of thermal and non-thermal X-rays from the shells of the super bubble (SB) 30 Dor C in the Large Magellanic Cloud (LMC). The X-ray morphology is a nearly circular shell...
X-Ray Observation on the Monoceros R2 Star-Forming Region with the Chandra ACIS-I Array (2003)
Nakajima, Hiroshi, Imanishi, Kensuke, Takagi, Shin-ichiro, Koyama, Katsuji, Tsujimoto, Masahiro
We report on the results of the Chandra observation on the central region of the Monoceros R2 cloud (Mon R2), a high-mass star-forming region (SFR). With a deep exposure of 100 ks, we detected 368...
Fine Structures of Shock of SN 1006 with the Chandra Observation (2003)
Bamba, Aya, Yamazaki, Ryo, Ueno, Masaru, Koyama, Katsuji
The north east shell of SN 1006 is the most probable acceleration site of high energy electrons (up to ~ 100 TeV) with the Fermi acceleration mechanism at the shock front. We resolved non-thermal...
Yokogawa, Jun, Imanishi, Kensuke, Tsujimoto, Masahiro, Koyama, Katsuji, Nishiuchi, Mamiko
We made 22 observations on the Small Magellanic Cloud (SMC) and covered full regions by the end of the ASCA mission. We detected 106 discrete sources with a criterion of S/N > 5 and performed...
Ueno, Masaru, Bamba, Aya, Koyama, Katsuji, Ebisawa, Ken
We present the Chandra results of AX J1843.8-0352, a supernova remnant (SNR) recently identified with ASCA. Chandra spatially resolved two components from this SNR: non-thermal and thermal ones. The...
Diffuse Hard X-ray Sources Discovered with the ASCA Galactic Plane Survey (2003)
Bamba, Aya, Ueno, Masaru, Koyama, Katsuji, Yamauchi, Shigeo
We found diffuse hard X-ray sources, G11.0+0.0, G25.5+0.0, and G26.6-0.1 in the ASCA Galactic plane survey data. The X-ray spectra are featureless with no emission line, and are fitted with both...
Imanishi, Kensuke, Kohno, Makoto, Koyama, Katsuji
Errors were made in the calculations of EMs using the best fit normalizations in XSPEC. Lists of the errors and corrections are as follows. (1)Tables 1, 3, and 4 in ApJ, 557, 747 and astro-ph/0104190...
Chandra and ASCA Observations of the X-ray-brightest T-Tauri Stars in the Rho Ophiuchi Cloud (2002)
Imanishi, Kensuke, Tsujimoto, Masahiro, Koyama, Katsuji
We present the Chandra ACIS and ASCA GIS results for a series of four long-term observations on DoAr 21, ROXs 21 and ROXs 31; the X-ray brightest T-Tauri stars (TTSs) in the Rho Ophiuchi cloud. In...
Bamba, Aya, Murakami, Hiroshi, Senda, Atsushi, Takagi, Shin-ichiro, Yokogawa, Jun, Koyama, Katsuji
This paper reports the diffuse X-ray features around the Galactic center observed with Chandra. We confirm the ASCA and Ginga discoveries of the large-scale thin-thermal plasma with strong lines in...
Chandra Observations of a New Supernova Remnant AX J1843.8-0352/G28.6-0.1 (2002)
Koyama, Katsuji, Ueno, Masaru, Bamba, Aya, Ebisawa, Ken
AX J1843.8-0352 is a new X-ray SNR identified to the radio complex G28.6-0.1 with the ASCA satellite. Chandra discovered two distinct components from this SNR: non-thermal and thin thermal X-ray...
Yokogawa, Jun, Imanishi, Kensuke, Koyama, Katsuji, Nishiuchi, Mamiko, Mizuno, Norikazu
This paper presents ASCA/SIS and ROSAT/HRI results of three supernova remnants (SNRs) in the Small Magellanic Cloud: 0103-726, 0045-734, and 0057-7226. The ROSAT/HRI images of these SNRs indicate...
Discovery of a Transient X-Ray Pulsar, AX J1841.0-0536, in the Scutum Arm Region with ASCA (2001)
Bamba, Aya, Yokogawa, Jun, Ueno, Masaru, Koyama, Katsuji, Yamauchi, Shigeo
We report on the discovery of a transient X-ray pulsar, AX J1841.0-0536, serendipitously found in the Scutum arm region with the ASCA in two separate observations. The X-ray flux is very faint at the...
Unusual diffuse X-ray source in the Galactic center region (2001)
Senda, Atsushi, Murakami, Hiroshi, Koyama, Katsuji
We report the ASCA and Chandra discovery of a diffuse X-ray source in the Galactic center region. The X-ray spectrum is fitted with a non-equilibrium ionization (NEI) plasma model of about 6-keV...
Chandra Observations of Embedded Young Stellar Objects (2001)
This paper reviews the Chandra deep exposure observations of star forming regions, rho-Ophiuchi, Orion Molecular Clouds 2 and 3, Sagittarius B2 and Monoceros R2. The results are; (1) class I...
ASCA X-ray source catalogue in the Galactic Center region (2001)
Sakano, Masaaki, Koyama, Katsuji, Murakami, Hiroshi, Maeda, Yoshitomo, Yamauchi, Shigeo
The ASCA satellite made 107 pointing observations on a 5 x 5 deg^2 region around the center of our Milky Way Galaxy (the Galactic Center) from 1993 to 1999. In the X-ray images of the 0.7--3 keV or...
X-Ray Observations on the Galactic Center Region (2001)
This paper reports on the early Chandra view of the Galactic center (GC) activities. The massive black hole Sgr A* is extremely faint, while more bright diffuse X-ray emission is prevailing in the...
Imanishi, Kensuke, Tsujimoto, Masahiro, Koyama, Katsuji
We present results of an X-ray search from bona-fide and candidate brown dwarfs in the Rho Ophiuchi cloud cores with the Chandra X-ray Observatory. The selected areas are two fields near the cloud...
X-ray source population of the Galactic center region obtained with ASCA (2001)
Sakano, Masaaki, Koyama, Katsuji, Murakami, Hiroshi, Maeda, Yoshitomo, Yamauchi, Shigeo
From the ASCA X-ray point-source list in the Galactic center 5x5 degree^2 region, we found the clear correlation between the position of the sources and the absorption. This fact implies that the...
Bamba, Aya, Ueno, Masaru, Koyama, Katsuji, Yamauchi, Shigeo
ASCA discovered an extended source in the Scutum constellation. The X-ray morphology is an elliptical shape elongated from north to south with a mean diameter of about 10'. The image center is...
A 168-s X-Ray Pulsar in the SMC Observed with ASCA (2001)
Yokogawa, Jun, Torii, Ken'ichi, Kohmura, Takayoshi, Koyama, Katsuji
This paper has been withdrawn because the class file must not be uploaded.
Chandra Observation of the Rho Oph Cloud (2001)
Imanishi, Kensuke, Koyama, Katsuji, Tsuboi, Yohko
We observed a 17$'\times17'$ region of the $\rho$ Oph molecular cloud, using the ACIS-I array onboard the {\it Chandra X-ray Observatory} (CXO). A 100-ks exposure observation revealed $\sim$ hundred...
Discovery of X rays from Class 0 protostar candidates in OMC-3 (2001)
Tsuboi, Yohko, Koyama, Katsuji, Hamaguchi, Kenji, Tatematsu, Ken'ichi, Sekimoto, Yutaro, Bally, John, ...
We have observed the Orion Molecular Clouds 2 and 3 (OMC-2 and OMC-3) with the Chandra X-ray Observatory (CXO). The northern part of OMC-3 is found to be particularly rich in new X-ray features; four...
ASCA Identification of SMC X-2 with the 2.37-s Pulsar Discovered by RXTE (2001)
Yokogawa, Jun, Torii, Ken'ichi, Kohmura, Takayoshi, Koyama, Katsuji
This paper has been withdrawn because the class file must not be uploaded.
Discovery of a 9-s X-Ray Pulsar, AX J0049-732, in the Small Magellanic Cloud (2000)
Ueno, Masaru, Yokogawa, Jun, Imanishi, Kensuke, Koyama, Katsuji
We report the ASCA discovery of a new X-ray pulsar, AX J0049-732, in the Small Magellanic Cloud (SMC). The pulse shape is sinusoidal with a barycentric period of 9.1320 +/- 0.0004 s. The X-ray...
Discovery of the Slowest X-Ray Pulsar in the SMC, AX J0049.5-7323, with ASCA (2000)
Yokogawa, Jun, Imanishi, Kensuke, Ueno, Masaru, Koyama, Katsuji
The discovery of coherent pulsations with ASCA from an X-ray source, AX J0049.5-7323, is reported. The barycentric period was determined to be 755.5 +/- 0.6 s, which is the longest among X-ray...
Discovery of 101-s Pulsations from AX J0057.4-7325 in the SMC with ASCA (2000)
Yokogawa, Jun, Torii, Ken'ichi, Kohmura, Takayoshi, Imanishi, Kensuke, Koyama, Katsuji
The results from two ASCA observations of AX J0057.4-7325 = RX J0057.3-7325 are presented. Coherent pulsations with a barycentric period of 101.45 +/- 0.07 s were discovered in the second...
ASCA Observations of the Twin Supernova Remnants in the Large Magellanic Cloud, DEM L316 (2000)
Nishiuchi, Mamiko, Yokogawa, Jun, Koyama, Katsuji, Hughes, John P.
We report results from an ASCA X-ray study of DEM L316, an emission nebula in the Large Magellanic Cloud (LMC) consisting of two closely-spaced supernova remnants (SNRs). The SIS image shows separate...
Yokogawa, Jun, Torii, Ken'ichi, Imanishi, Kensuke, Koyama, Katsuji
The results from three ASCA observations of AX J0051.6-7311 = RX J0051.9-7311 are reported. Coherent pulsations with a barycentric period of 172.40 +/- 0.03 s were discovered in the third...
Discovery of a Slow X-Ray Pulsator, AX J1740.1-2847, in the Galactic Center Region (2000)
Sakano, Masaaki, Torii, Ken'ichi, Koyama, Katsuji, Maeda, Yoshitomo, Yamauchi, Shigeo
We report the discovery of an X-ray pulsar AX J1740.1-2847 from the Galactic center region. This source was found as a faint hard X-ray object on 7--8 September 1998 with the ASCA Galactic center...
Discovery of Non-Thermal X-Rays from the Shell of RCW86 (2000)
Bamba, Aya, Koyama, Katsuji, Tomida, Hiroshi
We report the ASCA (Advanced Satellite for Cosmology and Astrophysics) results of RCW 86, a shell-like supernova remnant (SNR). The bright region in the X-ray band traces the radio clumpy shell,...
Broad-Band X-Ray Study of a Transient Pulsar RX J0059.2-7138 (2000)
Kohno, Makoto, Yokogawa, Jun, Koyama, Katsuji
We report on the results of the ASCA and ROSAT observations on RX J0059.2-7138, a transient X-ray pulsar in the Small Magellanic Cloud. The barycentric pulse period has been precisely determined to...
Deep X-Ray Observations of Supernova Remnants G359.1-0.5 and G359.0-0.9 with ASCA (2000)
Bamba, Aya, Yokogawa, Jun, Sakano, Masaaki, Koyama, Katsuji
We present the results of deep ASCA observations of two shell-like radio supernova remnants (SNRs) located in the direction to the Galactic center (GC) region. Unlike the radio morphology, G359.1-0.5...
A Study of the Populations of X-ray Sources in the Small Magellanic Cloud with ASCA (2000)
Yokogawa, Jun, Imanishi, Kensuke, Tsujimoto, Masahiro, Nishiuchi, Mamiko, Koyama, Katsuji, Nagase, Fumiaki, ...
The Advanced Satellite for Cosmology and Astrophysics (ASCA) has made multiple observations of the Small Magellanic Cloud (SMC). X-ray mosaic images in the soft (0.7--2.0 keV) and hard (2.0--7.0 keV)...
Quasi-periodic X-ray Flares from the Protostar YLW15 (1999)
Tsuboi, Yohko, Imanishi, Kensuke, Koyama, Katsuji, Grosso, Nicolas, Montmerle, Thierry
With ASCA, we have detected three X-ray flares from the Class I protostar YLW15. The flares occurred every ~20 hours and showed an exponential decay with time constant 30-60 ks. The X-ray spectra are...
Rotation and X-ray emission from protostars (1999)
Montmerle, Thierry, Grosso, Nicolas, Tsuboi, Yohko, Koyama, Katsuji
The ASCA satellite has recently detected variable hard X-ray emission from two Class I protostars in the rho Oph cloud, YLW15 (IRS43) and WL6, with a characteristic time scale ~20h. In YLW15, the...
Discovery of an X-Ray Pulsar in the SMC: AX J0058-7203 (1999)
Tsujimoto, Masahiro, Imanishi, Kensuke, Yokogawa, Jun, Koyama, Katsuji
We report on the discovery and analysis of an X-ray pulsar, AX J0058-7203, in the Small Magellanic Cloud. This pulsar exhibits coherent pulsations at P= 280.3 s with a double-peak structure. The...
ASCA Discovery of a Be X-Ray Pulsar in the SMC: AX J0051-733 (1999)
Imanishi, Kensuke, Yokogawa, Jun, Tsujimoto, Masahiro, Koyama, Katsuji
ASCA observed the central region of the Small Magellanic Cloud, and found a hard X-ray source, AX J0051-733, at the position of the ROSAT source RX J0050.8-7316, which has an optical counterpart of a...
Further studies of 1E 1740.7-2942 with ASCA (1999)
Sakano, Masaaki, Imanishi, Kensuke, Tsujimoto, Masahiro, Koyama, Katsuji, Maeda, Yoshitomo
We report the ASCA results of the Great Annihilator 1E 1740.7-2942 obtained with five pointing observations in a time span of 3.5 years. The X-ray spectrum for each period is well fitted with a...
The hardest X-ray source in the ASCA Large Sky Survey: Discovery of a new type 2 Seyfert (1998)
Sakano, Masaaki, Koyama, Katsuji, Tsuru, Takeshi, Awaki, Hisamitsu, Ueda, Yoshihiro, Takahashi, Tadayuki, ...
We present results of ASCA deep exposure observations of the hardest X-ray source discovered in the ASCA Large Sky Survey (LSS) project, designated as AX J131501+3141. We extract its accurate X-ray...
ASCA X-Ray Spectroscopy of LMC Supernova Remnants and the Metal Abundances of the LMC (1998)
Hughes, John P., Hayashi, Ichizo, Koyama, Katsuji
We present the results of X-ray spectroscopy of a flux-limited sample of seven middle-aged supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) (N23, N49, N63A, DEM71, N132D, 0453-68.5, and...
Wide-Band X-Ray Spectra and Images of the Starburst Galaxy M82 (1997)
Tsuru, Takeshi Go, Awaki, Hisamitsu, Koyama, Katsuji, Ptak, Andy
The ASCA results of the starburst galaxy M82 are presented. The X-rays in the 0.5--10 keV band exhibit a thin thermal spectrum with emission lines from highly ionized magnesium, silicon, and sulfur,...
ICM masses in nearby and distant clusters of galaxies (1997)
Tsuru, Takeshi Go, Matsumoto, Hironobu, Koyama, Katsuji, Tomida, Hiroshi, Fukazawa, Yashushi, Hattori, Makoto, ...
We compile X-ray data of clusters of galaxies at a wide range of redshift $z=0.0\sim1.0$ and compare X-ray luminosities, gas masses, iron abundances and iron masses of nearby clusters and those of...
Koyama, Katsuji, Kinugasa, Kenzo, Matsuzaki, Keiichi, Nishiuchi, Mamiko, Sugizaki, Mutusmi, Torii, Ken'ichi, ...
We report ASCA results of a featureless X-ray spectrum from RX J1713.7-3946, a new shell-like SNR discovered with the ROSAT all sky survey. The northwest part of RX J1713.7-3946 was in the field of...