摘要：Optically thin accretion plasmas can reach ion temperaturesTi ≥ 1010K and thus trigger nuclear reactions. Using a large nuclear interactions network, we studied the radial evolution of the chemical composition of the accretion flow toward the black hole and computed the emissivity in nuclearγ-ray lines. In the advection dominated accretion flow (ADAF) regime, CNO and heavier nuclei are destroyed before reaching the last stable orbit. The overall luminosity in the de-excitation lines for a solar composition of plasma can be as high as few times 10−5the accretion luminosity (Ṁc2) and can be increased for heavier compositions up to 10−3. The efficiency of transformation of the kinetic energy of the outflow into high energy (≥100 MeV)γ-rays through the production and decay ofπ0-mesons can be higher, up to 10−2of the accretion luminosity. We show that in the ADAF model up to 15% of the mass of accretion matter can “evaporate” in the form of neutrons.
关键词：enaccretion, accretion disksgamma rays: generalnuclear reactions, nucleosynthesis, abundancesstars: black holes
