Nucleosynthesis in accretion flows around black holes

Significant nucleosynthesis is possible in the centrifugal pressure-support ed dense and hot region of the accretion flows which deviate from Keplerian disks around black holes. We compute composition changes and energy genera tions due to such nuclear processes. We use a network containing 255 specie s and follow the changes in composition. Highly viscous, high-accretion-rat e flows deviate from a Keplerian disk very close to the black hole and the temperature of the flow is very small due to Compton cooling. No significan t nucleosynthesis takes place in these cases. Low-viscosity and lower-accre tion-rate hot flows deviate farther out and significant changes in composit ion are possible in these cases. We suggest that such changes in compositio n could be contributing to the metallicities of the galaxies. Moreover, the radial variation of the energy generation/absorption specifically due to p roton capture and photo-dissociation reactions could cause instabilities in the inner regions of the accretion flows. For most of these cases sonic po int oscillations may take place. We discuss the possibility of neutrino emi ssions.