Frontier of Energy and Distance of Very High Energy Gamma-Ray Astronomy

甚高能伽马射线天文学的能量与距离前沿

基本信息

批准号：
15540263
负责人：
KIFUNE Tadashi
金额：
$ 1.73万
依托单位：
Shinshu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15540263/
关键词：
Very High Energy Gamma Ray Astronomy Non-thermal Phenomena in the Universe Particle Acceleration Origin of Cosmic Rays Pari production of Electron and Positron Cosmic Background Radiation Sources of Very High Energy Gamma Rays Imaging Atmosp

项目摘要

Very energetic gamma rays collide with universal cosmic background radiation of microwave and infrared band to create pairs of electron and positrons, thus initiating a cascade process of creating a number of electrons and gamma rays in the extragalactic space. The effect of absorption and regeneration of gamma-rays which are radiated from far distant sources was calculated, in order to draw a view in near future of TeV Gamma Ray Astronomy and to study ultra high energy phenomena in the Universe.Regeneration of secondary gamma rays causes accumulation of gamma ray flux in the energy region around 10-100 TeV. However, the increasing factor of the flux is at most about 3 when energy spectrum of primary gamma rays is as hard as the power index alpha of -2, while the factor is less than 10% for in the case of alpha equal to 2.5. On the other hand, more prominent effect of the cosmic cascade can be caused by electrons, the secondary product of the cascade process, of energies higher than 10^{15} eV,. Such high energy electrons radiate synchrotron photons, of which energy would be into the lower energy band as high as GeV gamma rays, possibly to provide evidence of extremely high energy gamma rays. However, the process depends on the strength of magnetic field in the extragalactic space. Thus, there remain investigations to be done in more details. Another interesting feature which may appear is a spectral break in the energy spectrum of electrons, due to the transition from the Thomson scattering to Compton scattering in the collision of electrons with photons of the background radiation.The cascade process causes a considerable angular spread of incident gamma-rays, and the telescope with a wide field of view is expected to increase importance, as very high energy gamma ray astronomy extends into higher energy region and far distances.

非常有活力的伽马射线与微波和红外带的通用宇宙背景辐射相撞，以创建一对电子和正电子，从而启动了在外层次空间中创建许多电子和伽玛射线的级联过程。计算了从遥远来源辐射出的伽马射线的吸收和再生的影响，以便在TEV伽马射线天文学的不久将来展现观点，并研究宇宙中的超高能量现象。在10-100 TEV附近能量区域中γ射线磁通量的次级伽玛射线的再生。但是，当原代伽马射线的能量谱与-2的功率指数α一样困难时，通量的增加最多是3，而在α等于2.5的情况下，该因子小于10％。另一方面，宇宙级联反应的更突出的效果可能是由电子（级联过程的次要产物）引起的，高于10^{15} eV的能量。如此高的能电子辐射同步子光子，其中能量将进入与GEV伽马射线一样高的较低能带，可能提供极高的能量伽马射线的证据。但是，该过程取决于磁场外磁场的强度。因此，仍有更多细节进行调查。可能出现的另一个有趣的功能是电子的能量光谱中的光谱破裂，这是由于从汤森散射到康普顿散射的电子与背景辐射的光子碰撞中的碰撞中。级联过程会导致入射γ射线的角度传播相当大，而远距离的望远镜会增加远距离的远距离范围，而远距离的远距离远处是远处的远处。