Gamma Ray Study on High Energy Phenomena of Celestial objects

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Our preceding study before the year 1995 has enabled us (i) to commence operation of our 3.8m telescope of imaging Cerenkov lights for gamma ray detection, in 1992 the next year of the launching of Compton gamma ray satellite, (ii) to prove the powerful efficiency of high resolution camera by using the camera of the highest angular resolution until 1996, (iii) to show the ability of observations at large zenith angles for detecting very high energy gamma rays in 10-100 TeV region from the data observing the Crab from the southern hemisphere. Based on these technical development, we have discovered 1 TeV gamma rays from PSR B 1706-44.The results obtained in 1997 are : (1) Very high energy gamma rays (-1TeV) are emitted from a region displaced from the Vela pulsar position by about 0.1ﾟ, which is consistent with the position where the pulsar was born. By comparing the observed gamma ray intensity with X-ray's, the magnetic field in the emission region is estimated as weak as 4muG.(2) The energy spectrum of gamma rays from the Crab nebula is found to continue at least up to 50 TeV,which are the gamma rays of the highest energy that have ever been detected.(3) Very high energy gamma rays has been detected from a supernova remnant SN1006. The result demonstrates that the gamma rays are produced by about 100 TeV electrons, providing a direct evidence that these electrons are shock-acceletated in the north-east rim of the supernova remnant. (4) A hint of 1 TeV gamma rays has been obtained from a gamma ray pulsar PSR B 1509-58. The data in the last year (of a higher threshold energy) shows no indication of signal, suggesting a steep energy spectrum. (6) Other objects, such as a gamma ray burst, the Galactic center Sgr A^<**>, several active galactic nuclei, unidentified EGRET sources and close X-ray binaries, are observed in the 1997 fiscal year. The data are now under analysis.