Black Holes in the Early Universe, in Compact Binaries, and as Energy Sources Inside SolarType Stars.
Abstract
This thesis consists of three separate studies of roles that black holes might play in our universe. In the first part we analyze in detail the prospects for determining the fundamental cosmological parameters of our universe using the distanceredshift relation as obtained from binary coalescence gravitational waves. Using the current estimates of binary coalescence rates and projected "advanced" LIGO parameters, we conclude that the Hubble constant should be measurable with an error of a few per cent. On the other hand, the errors for the mean density of the universe and the cosmological constant will depend strongly on the size of the universe (as reflected in, e.g., mean distances between neighboring galaxies), thus varying from about 10% ("small" universe) up to and beyond 100% ("large" universe). We further study the effects of gravitational lensing and find that it may strongly impair the determination of the cosmological constant. In the second part we construct regular vacuum states for a quantum scalar field outside a black hole which resides in de Sitter spacetime. We study detection of the scalar particles by static observers, assuming the field in such a quantum state, and show that the detected flux is a superposition of thermal fluxes characterized by the temperatures of the black hole and cosmological horizons. This result agrees perfectly with the form of the (renormalized) stressenergy tensor. In the third part we study the evolution of a hypothetical primordial black hole that might have found its way into the center of the Sun or any other solartype star. As a foundation for our analysis, we generalize the mixinglength theory of convection to an optically thick, spherically symmetric accretion flow. When the accretion is that of solar matter onto the hole, the rotation of the Sun leads to the formation of an "accretion torus" near the hole, which produces an enhanced outflow of heat. We find, however, that the turbulent viscosity, which accompanies the convective transport of this heat, extracts angular momentum from the inflowing gas, thereby buffering the torus into a lower luminosity than one might have expected. As a result, the solar surface will not be influenced noticeably by the torus's luminosity until at most three days before the Sun is finally devoured by the black hole. As a corollary, accretion onto a black hole inside the Sun cannot be an answer to the solar neutrino puzzle.
 Publication:

Ph.D. Thesis
 Pub Date:
 1994
 Bibcode:
 1994PhDT.........3M
 Keywords:

 Physics: Astronomy and Astrophysics;
 Binary Stars;
 Black Holes (Astronomy);
 Computational Astrophysics;
 Cosmology;
 Energy Sources;
 Main Sequence Stars;
 Red Shift;
 SpaceTime Functions;
 Thermal Emission;
 Universe;
 Angular Momentum;
 Coalescing;
 Convection;
 Estimates;
 Hubble Constant;
 Mixing Length Flow Theory;
 Stellar Structure;
 Vacuum Effects;
 Astrophysics