Cosmic gamma rays

The composition and implications of gamma rays observed by satellites are discussed. SAS II and COS B data from the direction of the Crab and Vela pulsars, 3C273, and the molecular cloud in the vicinity of Rho Oph are examined. It is noted that the 2-3 deg resolution of the detectors demands the consideration that cosmic ray electrons interacting with the interstellar medium could invalidate any positive definition of a particular source. Mechanisms of cosmic ray production by interstellar clouds are reviewed, and evidence is cited for a possible galactic source of some of the emissions. Observations of a 100 MeV flux coming from the direction of 2CGl95 + 04, through a relatively uncluttered region, does suggest a discrete source. Extragalactic rays possibly originate in the galactic halo. Models of equal X ray flux from all directions, with some enhancement from directions containing galaxies, seem to correspond with observations.