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UBC Theses and Dissertations

Topics in black hole evaporation Leahy, Denis Alan


Two major aspects of particle creation by gravitational fields of black holes are studied; the neutrino emission from rotating black holes; and interactions between scalar particles emitted by a black hole. The neutrino emission is investigated under three topics. The asymmetry of the angular dependence of neutrino emission from rotating black holes is calculated first. A low frequency analytic approximation demonstrates the preferential emission of neutrinos (antineutrinos) antiparallel (parallel) to the direction of the black hole's angular momentum vector. Numerical calculations are performed which reveal the dependence of the neutrino emission on polar angle, neutrino energy, and black hole angular momentum and mass. Next we consider the production of a local matter excess by rotating black holes in a baryon symmetric universe. Black holes form at early cosmological times with their rotation axes aligned over the same scale size as the angular momentum in the universe. The evaporation of these black holes produces large scale neutrino currents, whose effectiveness in separating baryons from antibaryons during the hadron era of the early universe is estimated. The local baryon to photon ratio over a galactic size scale depends on the subsequent evolution of the resulting matter and antimatter regions, but is found to have an upper limit of 10 ⁻¹⁴. This is much less than the present observed value of about 10⁻⁹. We then study cosaological magnetic field generation by neutrinos from evaporating black holes. During the radiation era the neutrinos scatter off protons and alectrons, producing a net charge current. This current generates magnetic fields. If present in large enough numbers, rotating black holes could account for the present observed magnetic field in our galaxy. Finally we study the effects of interactions on the black hole evaporation process. Perturbation theory is used, to second order, to calculate the effects of a 2Ф⁴ self-interaction for a scalar field Ф in the 2 dimensional black hole spacetime. a mass renormalization was found to be insufficient to remove all divergences that occur in the calculations. However, the interaction appears to destroy the thermal character of the emission from a black hole evaporating in a vacuum.

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