Neutrino-cooled accretion disks around spinning black holes

We calculate the structure of accretion disks around Kerr black holes for accretion rates. M 0: 001Y10 M-circle dot s(-1). Such high-M disks are plausible candidates for the central engine of gamma-ray bursts. Our disk model is fully relativistic and accurately treats the microphysics of the accreting matter: neutrino emissivity, opacity, electron degeneracy, and nuclear composition. The neutrino-cooled disk forms above a critical accretion rate. M-ign that depends on the black hole spin. The disk has an "ignition'' radius r(ign) where neutrino flux rises dramatically, cooling becomes efficient, and the proton-to-nucleon ratio Ye drops. Other characteristic radii are r(alpha), where most of alpha-particles are disintegrated, r(nu), where the disk becomes nu-opaque, and r(tr), where neutrinos get trapped and advected into the black hole. We find r(alpha), r(ign), r(nu), and r(tr) and show their dependence on. M. We discuss the qualitative picture of accretion and present sample numerical models of the disk structure. All neutrino-cooled disks regulate themselves to a characteristic state such that: (1) electrons are mildly degenerate, (2) Y-e similar to 0: 1, and (3) neutrons dominate the pressure in the disk.