Galactic structure and gamma radiation.

A new model on the structure of the galaxy, based on gamma radiation data using a new window on the local galaxy, is discussed and compared with existing models; data obtained via the SAS II satellite are considered. The proposed model deals with both synchrotron radiation from neutral H and gamma radiation, with density waves taken into account; the Georgelin (1975) model and other models are compared. Lack of an objective general distance criterion and poor resolution of gamma radiation data are noted as obstacles. The SAS-II data and COS-B data to come, as well as data from instruments that can be orbited by Space Shuttle in the near future, promise higher resolution and greater detail on the distribution of gaseous matter, on relations between matter, fields, and cosmic rays, and on star formation and galactic shape.