HUGE EJECTION OF ANTIELECTRON NEUTRINOS FROM MASSIVE ACCRETION DISKS

Abstract

The standard massive accretion disk with Keplerian angular momentum (standard accretion disk) producing gamma-ray bursts (GRBs) is investigated on the bases of the microphysics of neutrinos and general relativity. Since the accretion disk gradually heated by viscosity is efficiently cooled by antielectron neutrinos, , the accreting flow maintains a relatively low temperature, T 3 × 1010 K, over a long range of accreting radius that produces very high dense matter around a rotating black hole, ρ ≥ 1013 g cm–3. Thus, the massively accreting matter is in the domain of heavy nuclei all over the accreting flow onto a central black hole where the fraction of evaporated free neutrons is large, Yn 0.8, and that of protons is infinitesimal, Yp 10–4. The electron neutrinos in the disk are almost absorbed by rich neutrons while the antielectron neutrinos are little absorbed by rarefied protons. The mean energy of antielectron neutrinos ejected from the disk is extraordinarily high, MeV, because the antielectron neutrinos are degenerated in the high dense disk. The huge antielectron neutrinos with high mean energy and large luminosity, erg s–1, are ejected from the massive accretion disk. The antielectron neutrinos are possibly the sources of the relativistic jets producing GRBs.