High Energy Gamma-Ray Observations of Peculiar Objects such as Pulsars and Active Galaxies

(1)到1994财政年度结束时，我们已经获得了来自蟹状星云和PSR B 1706-44的VHE(甚高能)伽马射线的证据。1993年和1994年获得的数据表明，船帆星脉冲星方向的VHe伽马射线信号是一个有趣的线索，数据分析加上1995年的观测，继续对船帆星和南方天空中的其他各种物体进行观测。(2)我们发现，1993-1995年的船帆星脉冲星方向的VHe伽马射线证据都存在于船帆星脉冲星方向的所有数据集。观测到的信号是“非脉冲”的(不受毫秒的脉冲星周期调制)，VHe伽马射线的发射区被扩展，其最大强度从脉冲星位置移动了约0.1ﾟ。这些特征表明VHe发射不是来自脉冲星磁层。高能电子和正电子的“风”(脉冲星风)被认为是从脉冲星喷出的，通过与星周物质碰撞发射伽马射线而产生冲击波。我们很可能在船帆脉冲星附近看到过这样的现象。(3)从双星脉冲星PSR B 1259-63，我们获得了约5西格玛意义的证据，这鼓励了重复观测。(4)我们设定了来自PKS 0521-365的VHe伽马射线通量上限，PKS 0521-365是康普顿伽马射线天文台伽马射线卫星探测到的第二近的活动星系核。(5)我们还研究了GeV伽马源的探测对象CGRO J 1758-23，它包括超新星遗迹、脉冲星、射电点源和分子云等。到目前为止，还没有发现VHE伽马射线以点源的形式出现的证据，扩展发射的情况还有待更仔细的研究。(6)初步分析表明，没有证据表明VHE辐射来自其他天体，如半人马座AGN A和脉冲星PSR B 1055-52。

(1) We have, by the end of the fiscal year 1994, obtained evidence of VHE (very high energy) gamma rays from Crab nebula and PSR B 1706-44. The data obtained in 1993 and 1994 suggested an interesting hint of VHE gamma ray signal from Vela pulsar direction, and data analysis, adding 1995 observation, was continued on the Vela as well as on other various objects in the southern sky.(2) We found that evidence of VHE gamma rays from Vela pulsar direction exist in all of the Vela data set over 1993 to 1995. The observed signal appears as "unpulsed" (not modulated with the pulsar period of 89 msec) and the emission region of VHE gamma rays is extended with its maximum intensity shifted by about 0.1ﾟ from the pulsar position. These features suggest that the VHE emission is not from the pulsar magnetosphere. A "wind" of energetic electrons and positrons (pulsar wind) is believed to be ejected from pulsar, causing a shock by colliding with circumstellar matter to emit gamma rays. It is likely that we have seen such a phenomenon in vicinity of the Vela pulsar.(3) From a binary pulsar PSR B 1259-63, we obtained evidence of about 5sigma significance, which encourages repeated observation.(4) We set an upper limit of VHE gamma ray flux from PKS 0521-365, the second nearest AGN (active galactic nuclei) among the GeV gamma ray AGN detected by the gamma ray satellite of Compton Gamma Ray Observatory. The result constrains on various models of gamma ray production as well as on infrared intensity in the extragalactic space.(5) We also studied an intesting object of GeV gamma ray source, CGRO J 1758-23, which includes supernova remnant, pulsar, radio point source and molecular cloud etc. No evidence of VHE gamma rays that appears as a point source was so far discovered, and the case of extended emission remains to be more carefully examined.(6) Prelimiary analysis shows no evidence of VHE emission from other objects such as AGN Centaurus A and pulsar PSR B 1055-52.