Theoretical Estimates of γ-Ray Emission

Abstract

In Table II-2 we have listed several astrophysical sites where γ-ray line production might be expected. In the case of the galactic disk, core, and the Sun, the calculation of the expected γ-ray fluxes from the different production mechanisms is on a reasonably firm basis since experimental results are available (cf. Sections V-5.1 and V-5.2). In addition, the evidence for a γ-ray line feature near 500 keV from the direction of the Galactic Center (Section V-5.2.3) has given rise to a flurry of theoretical predictions as to the origin of this feature. The same is true for the γ-ray bursts discovered on the Vela satellites (Section V-5.4). We will review here the predicted fluxes from several sources listed in Table II-2. Since the case of γ-ray production in the solar atmosphere has received considerable treatment, we will review these calculations in more detail than for other sources, since the results are generally applicable to any astrophysical source where a solar abundance is a reasonable approximation. Only those theoretical predictions for other sources will be discussed here that seem most pertinent to γ-ray line astronomy. The experimental evidence for γ-ray fluxes in the nuclear transition region is described in Chapter V, and reference to the discussion there should be made when considering such material in this chapter.