Cos-B and Cosmology
Abstract
The 1 to 100 MeV gamma-ray background is currently believed to be of cosmological origin. It has been suggested that it originates from neutral pion decay, either in a burst of cosmological cosmic rays (CCR) interacting with the ambient gas or in some annihilation process between macroscopic regions of matter and antimatter, both at high redshifts (zs equals about 100). It is thus of interest to see to what extent present-day experiments are fitted to test such hypotheses, for instance by revealing the presence of spatial fluctuations in the gamma-ray background due to photons coming from zs. To this end and for ESA's COS-B gamma-ray satellite, the corresponding theoretical spectra are folded through the efficiency of the detector, in order to compute COS-B's gamma-ray visibility function (Montmerle 1975). Because of its reduced efficiency at energies less than 70 MeV, COS-B sees only local background gamma-ray photons (i.e. coming essentially from z less than 10) in the annihilation hypothesis. The situation is somewhat better in the CCR hypothesis, but the image contrast should be rather poor. COS-B is thus not well suited to give information on high-energy phenomena occurring at high redshifts.
- Publication:
-
Recent Advances in Gamma-Ray Astronomy
- Pub Date:
- July 1977
- Bibcode:
- 1977ESASP.124..235M
- Keywords:
-
- Cos-B Satellite;
- Cosmology;
- Gamma Rays;
- Background Radiation;
- Cosmic Rays;
- Pions;
- Red Shift;
- Visibility;
- Astrophysics