Neutrino-cooled accretion disks around spinning black holes

We calculate the structure of accretion disk around a spinning black hole for accretion rates M = 0.01 - 10M(circle dot) s(-1). The model is fully relativistic and treats accurately the disk microphysics including neutrino emissivity, opacity, electron degeneracy, and nuclear composition. We find that the accretion flow always regulates itself to a mildly degenerate state with the protonto-nucleon ratio Y-e less than or similar to 0.1 and becomes very neutron-rich. The disk has a well defined "ignition" radius where neutrino flux raises dramatically, cooling becomes efficient, and Y-e suddenly drops. We also calculate other characteristic radii of the disk, including the v-opaque and v-trapping radii, and show their dependence on A Accretion disks around fast-rotating black holes produce intense neutrino fluxes which may deposit enough energy above the disk to generate a GRB jet.