Kazuhisa Mitsuda

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We present results from Chandra observations of SDSS J1004+4112, a strongly lensed quasar system with a maximum image separation of 15 ′′. All four bright images of the quasar, as well as resolved X-ray emission originating from the lensing cluster, are clearly detected. The emission from the lensing cluster extends out to approximately 1. ′ 5. We measure(More)
The NeXT (New exploration X-ray Telescope), the new Japanese X-ray Astronomy Satellite following Suzaku, is an international X-ray mission which is currently planed for launch in 2013. NeXT is a combination of wide band X-ray spectroscopy (3–80 keV) provided by multi-layer coating, focusing hard X-ray mirrors and hard X-ray imaging detectors, and high(More)
We have measured the phase differences between X-ray intensity variations in different energy bands in data taken with Ginga of the Z source GX 5-1 in its normal branch. We apply a χ 2 optimal extraction technique to measure the phase-delay spectrum of the normal-branch quasi-periodic oscillations (QPO) and find a jump at 3.5 keV. X-ray intensity variations(More)
In order to develop lightweight and high angular resolution x-ray mirrors, we have investigated hot plastic deformation of 4 in. silicon (111) wafers. A sample wafer was deformed using hemispherical dies with a curvature radius of 1000 mm. The measured radius of the deformed wafer was 1030 mm, suggesting that further conditioning is indispensable for better(More)
We have studied the spectral and rapid variations of GS 2023+338 using all Ginga (LAC) data available of this source. We used colour-colour and hardness-intensity diagrams to study the spectral behaviour and for the variability behaviour we used the FFT-technique to obtain power spectra, the energy dependence of the variability and the energy dependence of(More)
We searched for absorption lines of highly ionized O and Ne in the energy spectra of two Low-mass X-ray binaries, 4U1820–303 in the globular cluster NGC6624 and Cyg X-2, observed with the Chandra LETG, and detected O VII, O VIII and Ne IX absorption lines for 4U1820–303. The equivalent width of the O VII K α line was 1.19 +0.47 −0.30 eV (90 % errors) and(More)
  • M Ba Luci´nska-Church, T Takahashi, +4 authors And H Inoue
  • 1997
We report the discovery of the cessation of flickering in dips in the black hole candidate Cygnus X-1, detected for the first time in the ASCA observation of May 9th., 1995. During this observation, particularly deep dipping took place resulting in strong changes in hardness ratio corresponding to absorption of the power law spectral component. The deadtime(More)
The X-ray emission from the central region of the Galactic plane, |l| 45 • and |b| 0. • 4, was studied in the 0.7–10 keV energy band with a spatial resolution of ∼ 3 ′ with the ASCA observatory. We developed a new analysis method for the ASCA data to resolve discrete sources from the extended Galactic ridge X-ray emission (GRXE). We successfully resolved(More)
Received ; accepted – 2 – ABSTRACT Studies were made of ASCA spectra of seven ultra-luminous compact X-ray 39−40 ergs s −1 , they are thought to represent a class of enigmatic X-ray sources often found in spiral galaxies. For some of them, the ASCA data are newly processed, or the published spectra are reanalyzed. For others, the published results are(More)
Most of cosmic baryons predicted by the big-bang nucleosynthesis has evaded the direct detection. Recent numerical simulations indicate that approximately 30 to 50 percent of the total baryons in the present universe is supposed to take a form of warm/hot intergalactic medium (WHIM) whose X-ray continuum emission is very weak. To identify those missing(More)