Gamma-ray line emission, nuclear destruction and neutron production in hot astrophysical plasmas. The deuterium boiler as a gamma-ray source

In hot astrophysical plasmas with ion temperatures high enough for nuclear excitation ($$\geqslant 10^{11} \enspace \text K$$) inelastic spallation reactions can proceed at a higher or similar rate leading to nuclei destruction during the stationary high-temperature plasma formation time. Therefore the nuclei manage to be excited before destruction, but on the average not more than once. As a result the nuclear line luminosity is strongly depressed and does not exceed 10⁻³ − 10⁻⁴ of the total luminosity which is associated mainly with the electron component of the plasma. In the quasi-stationary sources of hard radiation (e.g. accretion discs) a proton–neutron plasma is formed due to nuclear destruction without a noticeable content of heavy nuclei. In the two-temperature plasma ($$T_i \gt T_e$$) the nucleons lose their energy mainly through elastic collisions. Besides, the nucleons radiatively cool due to neutron capture by protons (with deuterium production) and bremsstrahlung during the proton–neutron scattering. The possibility of neutron evaporation from the two-temperature accretion discs is discussed.