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Naoki Oda 《Space Science Reviews》1983,36(3):285-292
The gamma-ray emissivity for the narrow component (FWHM = 2°) at the 0.3–5 GeV range is derived as a function of the galactocentric distance. The narrow component might result from the interaction between cosmic rays and H2 gas. The mass of gas in the Galactic Center is not large enough to produce the gamma-ray peak, but enough to produce the far-infrared peak. The relation of far-infrared dip and near-infrared hump near l = 356° to gamma-ray hump is discussed. 相似文献
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S. Drapatz L. Haser R. Hofmann N. Oda R. Wilczek 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(3):7-10
Far-infrared observations of the Galactic Center have been carried through with the MPE Im balloon-borne telescope “Golden Dragon”. The measurements are composed of photometric scanning (33–95 μm) of the inner 4′×4′ and low resolution spectroscopy (δν = 10 cm?1) of the center and of a position approximately 1.5′ to the north. A Mars spectrum has been obtained for calibration. The spatial resolution of the photometry map is increased using the Maximum Entropy Method and the resulting map is compared to other observations in the same and other spectral regions. A clear asymmetry in the ring-like structure around the center indicates the presence of noncircular motions. The shape of the spectra is fairly smooth with at least no prominent dust features. A simple modelling shows a drastic increase of column density within 2 pc from the center and a modest drop over the next 3 pc to the north. 相似文献
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Minoru Oda 《Space Science Reviews》1977,20(6):757-813
Among discrete galactic X-ray sources, Cyg X-1 has been noted for its peculiar features in several respects. It is one of
the few sources with a hard power law spectrum extending beyond several hundred keV. Cyg X-1 also distinguishes itself by
its profound time variability over a wide range of time scales. The most remarkable incident was that its optical identification
with a spectroscopic binary HDE226868 has led to a presumption that it is a black hole. This possibility has induced continuous
interests in the physical character of this source in conjunction with the nature of the black hole. The purpose of this paper
is to summarize presently available pieces of knowledge on this source to help the design of future experimental and theoretical
works, while the complexity of the source characteristics still has prevented us to construct a clear, coherent picture of
this source in spite of the fact that numerous observational facts have been accumulated. 相似文献
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M. Oda 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(4):207-216
Imaging over the hard X-ray energy band may be achieved by masking the flux with proper obstacles. The imaging modulation collimator has been developed and has been applied thus far, e.g., to produce hard X-ray pictures of the solar flare and to construct the X-ray image of the Crab Nebula up to the angular resolution of ~ 10 arcsec. Variations of the concept such as the Fourier Transform Telescope are discussed. Virtue of the modulation collimator is that high angular resolution may be achieved with a relatively simple detector system and that a wide field of view may be accomodated. Among several proposed coded masks, the techniques of Hadamard transform are discussed in some details. The coded mask is provided with a better total transmission, but its angular resolution is limited due to presently limited spatial resolution of the detector. Developments of the technique of the position sensitive detector are awaited for further improvements of the resolution. 相似文献
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K. Makishima Y. Ogawara M. Matsuoka M. Oda S. Miyamoto R. M. Pelling L. E. Peterson W. S. Paciesas 《Space Science Reviews》1981,30(1-4):259-262
Two-dimensional maps of the Crab Nebula have been synthesized in 22–64 keV range through the modulation collimator experiment. The effective angular resolution is about 15. The result indicates that the Crab morphology is strictly controlled by the pulsar. 相似文献