Ground-based detection of very high energy gamma rays at Tev energies is discussed by using as example the emission from pulsar nebulae and supernova remnants. Copious production of electrons and positrons characterizes the point sources of gamma rays, and the radiation of electrons links TeV region tightly to the other bands, giving us the means of the `multi-wavelengths analysis' to investiga...

The development of techniques whereby gamma rays of energy 100 GeV and above can be studied from the ground, using indirect, but sensitive, techniques has opened up a new area of high energy photon astronomy. The most exciting result that has come from these is the detection of highly variable fluxes of TeV gamma rays from the relativistic jets in nearby AGN. The recent detection of signals fro...

Copious production of electrons and positrons results in very high energy gamma-rays from the sources such as pulsar nebulae and supernova remnants. The emission at TeV energies is characterized and controlled by the interaction of high energy photons and electrons. The radiation of electrons links the TeV region tightly to the other bands, giving us the means of `multiwavelengths analysis' to ...

Clusters of galaxies have not yet been detected at gamma-ray frequencies; however, the recently launched Fermi Gamma-ray Space Telescope, formerly known as GLAST, could provide the first detections in the near future. Clusters are expected to emit gamma rays as a result of (1) a population of high-energy cosmic rays fueled by accretion, merger shocks, active galactic nuclei and supernovae, and ...

Annihilating dark matter particles produce roughly as much power in electrons and positrons as in gamma ray photons. The charged particles lose essentially all of their energy to inverse Compton and synchrotron processes in the galactic environment. We discuss the diffuse signature of dark matter annihilations in satellites of the Milky Way (which may be optically dark with few or no stars), pr...