Prompt gamma rays and X rays from supernovae

Abstract

The hydrodynamic origin of cosmic rays (Colgate and Johnson 1960) depends upon the shock ejection of the outer layers of the supernova. The increase in energy of the shock to c2 per gram occurs relatively deep within the star where the fraction, F, of mass external to this layer is 10−4. The relativistic shock wave continues to increase in strength in the decreasing density of the envelope. When the shock "breaks through" the surface denned as one Compton scattering mean free path at radius R, then the energy factor [Formula: see text]. The temperature in the proper frame of the shock is determined by the condition aT4 = 2γs2ρ0, where ρ0 is the initial rest density ahead of the shock. For a typical presupernova star, [Formula: see text], and polytrope of index 3, the temperature becomes (1.7–2) × 105 eV at the surface layer. Photons emitted from the moving surface layer will be Doppler-shifted from their mean proper frame value of 3kT to a final energy [Formula: see text].Photons originating in, and emitted from, the surface layer before the layer expands adiabatically will have the upper limiting energy. As adiabatic expansion of subsequent layers takes place, photons diffusing from greater depths will be emitted at sequentially lower energy. The total energy in the photon pulse from the surface layer becomes [Formula: see text] ergs, or 50 ergs/cm2 at the earth for a supernova within our galaxy. The time of emission becomes [Formula: see text] (Petschek 1967).