Analyses are given of various processes involving matter falling\r\ninto or coming out of black holes.

\r\n\r\nA significant amount of matter may fall into a black hole in a\r\ngalactic nucleus or in a binary system. There gas with relatively high\r\nangular momentum is expected to form an accretion disk flowing into the\r\nhole. In this thesis the conservation laws of rest mass, energy, and\r\nangular momentum are used to calculate the radial structure of such a\r\ndisk. The averaged torque in the disk and flux of radiation from the\r\ndisk are expressed as explicit, algebraic functions of radius.

\r\n\r\nMatter may be created and come out of the gravitational field of\r\na black hole in a quantum-mechanical process recently discovered by\r\nHawking. In this thesis the emission rates of massless particles by\r\nHawking's process are computed numerically. The resulting power spectra\r\nof neutrinos, photons, and gravitons emitted by a nonrotating hole are\r\ngiven. For rotating holes, the rates of emission of energy and angular\r\nmomentum are calculated for various values of the rotation parameter.\r\nThe evolution of a rotating hole is followed as energy and angular\r\nmomentum are given up to the emitted particles. It is found that angular\r\nmomentum is lost considerably faster than energy, so that a black\r\nhole spins down to a nearly nonrotating configuration before it loses a\r\nlarge fraction of its mass. The implications are discussed for the lifetimes and possible present configurations of primordial black\r\nholes (the only holes small enough for the emission to be significant\r\nwithin the present age of the universe.

\r\n\r\nAs an astrophysical application, a calculation is given of the\r\ngamma-ray spectrum today from the emission by an assumed distribution\r\nof primordial black holes during the history of the universe. Comparison\r\nwith the observed isotropic gamma-ray flux above about 100 MeV yields\r\nan upper limit of approximately 10^4 pc^(-3) for the average number density\r\nof holes around 5 x 10^(14)g. (This is the initial mass of a nonrotating\r\nblack hole that would just decay away in the age of the universe.) The\r\nprospects are discussed for observing the final, explosive decay of an\r\nindividual primordial black hole. Such an observation could test the\r\ncombined predictions of general relativity and quantum mechanics and\r\nalso could provide information about inhomogeneities in the early universe\r\nand about the nature of strong interactions at high temperatures.

\r\n", "doi": "10.7907/RAEC-8822", "publication_date": "1976", "thesis_type": "phd", "thesis_year": "1976" } ]