Search Publications
A Time-Variable X-Ray Echo: Indications of a Past Flare of the Galactic-Center Black Hole
Koyama, Katsuji; Matsumoto, Hironori; Tsuru, Takeshi Go +1 more
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 Diffuse X-rays, and is thus time invariable. By comparing the 6.68keV and 6.40keV line fluxes, we found that the 6.40keV flux from the Sgr B2 complex …
Spectral Study of the Galactic Ridge X-Ray Emission with Suzaku
Tsujimoto, Masahiro; Kokubun, Motohide; Koyama, Katsuji +7 more
In order to carry out a precise spectral study of the Galactic Ridge X-ray Emission using Suzaku, we have observed a typical Galactic plane field at (l,b) = (28°46, -0°20), which is already deeply observed with Chandra, and known to be devoid of bright X-ray point sources. Thanks to the low background and high spectral resolution of Suzaku, we wer…
Measuring the Broad-Band X-Ray Spectrum from 400eV to 40keV in the Southwest Part of the Supernova Remnant RXJ1713.7-3946
Petre, Robert; Kokubun, Motohide; Nakazawa, Kazuhiro +13 more
We report on results from Suzaku broadband X-ray observations of the southwest part of the galactic supernova remnant (SNR) RXJ1713.7-3946 with an energy coverage of 0.4-40keV. The X-ray spectrum, presumably of synchrotron origin, is known to be completely lineless, making this SNR ideally suited for a detailed study of the X-ray spectral shape fo…
Suzaku Spectroscopy of an X-Ray Reflection Nebula and a New Supernova Remnant Candidate in the SgrB1 Region
Koyama, Katsuji; Nakajima, Hiroshi; Matsumoto, Hironori +7 more
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 SXV, FeI, FeXXV, and FeXXVI were clearly detected in the spectrum. We found that the FeXXV and FeXXVI line emissions smoothly distribute over the SgrB1 and B2 regions connecting from the …
In-Orbit Timing Calibration of the Hard X-Ray Detector on Board Suzaku
Dotani, Tadayasu; Enoto, Teruaki; Yamaoka, Kazutaka +28 more
The hard X-ray detector (HXD) aboard the X-ray satellite Suzaku is designed to have a good timing capability with a 61µs time resolution. In addition to detailed descriptions of the HXD timing system, results of in-orbit timing calibration and the performance of the HXD are summarized. The relative accuracy of time measurements of the HXD ev…
Suzaku Observations of the North Polar Spur: Evidence for Nitrogen Enhancement
Miller, Eric D.; Katsuda, Satoru; Kokubun, Motohide +10 more
We present observations of the North Polar Spur (NPS) using the X-ray Imaging Spectrometer (XIS) aboard the Suzaku X-ray satellite. The NPS is a large region of enhanced soft X-ray and radio emission projected above the plane of the Galaxy, likely produced by a series of supernovae and stellar winds from the nearby Sco-Cen OB association. The exce…
Hinode's Observational Result on the Saturation of Magnetic Helicity Injected into the Solar Atmosphere and Its Relation to the Occurrence of a Solar Flare
Magara, Tetsuya; Tsuneta, Saku
This paper is intended to present key features of the evolution toward the onset of a solar flare, using Hinode's observations on the photospheric magnetic field. Hinode can provide the temporal development of the photospheric field as a vector quantity, which shows that magnetic shear is initially developed in a flare-productive active region (AR…
VLBI Astrometry of AGB Variables with VERA --- A Semiregular Variable S Crateris ---
Hirota, Tomoya; Kurayama, Tomoharu; Honma, Mareki +40 more
We present a distance measurement for the semiregular variable S Crateris (S Crt) based on its annual parallax. With the unique dual beam system of the VLBI Exploration for Radio Astrometry (VERA) telescopes, we measured the absolute proper motion of a water maser spot associated with S Crt, referred to the quasar J1147-0724 located at an angular …
Suzaku Observations of Hercules X-1: Measurements of the Two Cyclotron Harmonics
Dotani, Tadayasu; Enoto, Teruaki; Kokubun, Motohide +10 more
The accretion-powered pulsar Her X-1 was observed with Suzaku twice in its main-on state, on 2005 October 5--6 and 2006 March 29--30, for a net exposure of 30.5ks and 34.4ks, respectively. In the 2005 and 2006 observations, the source was detected at an average 10--30keV intensity of 290mCrab and 230mCrab, respectively. The intrinsic pulse period …
Wide-Band Spectroscopy of the Compton Thick Seyfert2 Galaxy Markarian 3 with Suzaku
Isobe, Naoki; Kunieda, Hideyo; Okajima, Takashi +15 more
We obtained a wide-band spectrum of the Compton-thick Seyfert2 galaxy Mkn3 with Suzaku. The observed spectrum was clearly resolved into weak, soft power-law emission, a heavily absorbed power-law component, cold reflection, and many emission lines. The heavily absorbed component, absorbed by gas with a column density of 1.1 × 1024 cm