Cosmological Black Holes as Models of Cosmological Inhomogeneities (2006)
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BibTeX
@MISC{McClure06cosmologicalblack,
author = {Megan L. McClure},
title = { Cosmological Black Holes as Models of Cosmological Inhomogeneities},
year = {2006}
}
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Abstract
Since cosmological black holes modify the density and pressure of the surrounding universe, and introduce heat conduction, they produce simple models of cosmological inhomogeneities that can be used to study the effect of inhomogeneities on the universe's expansion. In this thesis, new cosmological black hole solutions are obtained by generalizing the expanding Kerr-Schild cosmological black holes to obtain the charged case, by performing a Kerr-Schild transformation of the Einstein-de Sitter universe (instead of a closed universe) to obtain non-expanding Kerr-Schild cosmological black holes in asymptotically- at universes, and by performing a conformal transformation on isotropic black hole spacetimes to obtain isotropic cosmological black hole spacetimes. The latter approach is found to produce cosmological black holes with energy-momentum tensors that are physical throughout spacetime, unlike previous solutions for cosmological black holes, which violate the energy conditions in some region of spacetime. In addition, it is demonstrated that radiation-dominated and matter-dominated Einstein-de Sitter universes can be directly matched across a hypersurface of constant time, and this is used to generate the rst solutions for primordial black holes that evolve from being in radiation-dominated background universes to matter-dominated background universes. Finally, the Weyl curvature, volume expansion, velocity field, shear, and acceleration are calculated for the cosmological black holes. Since the non-isotropic black holes introduce shear, according to Raychaudhuri's equation they will tend to decrease the volume expansion of the universe. Unlike several studies that have suggested the relativistic backreaction of inhomogeneities would lead to an accelerating expansion of the universe, it is concluded that shear should be the most likely influence of inhomogeneities, so they should most likely decrease the universe's expansion.
Keyphrases
cosmological black hole abstract cosmological black hole cosmological inhomogeneity volume expansion cosmologi-cal inhomogeneity weyl curvature isotropic black hole spacetimes relativistic backreaction likely decrease isotropic cosmological black hole spacetimes closed universe latter approach conformal transformation kerr-schild cosmological black hole kerr-schild transformation energy condition energy-momentum tensor non-expanding kerr-schild cosmo-logical black hole charged case non-isotropic black hole simple model cos-ii mological black hole heat conduction primordial black hole matter-dominated background universe velocity eld constant time matter-dominated einstein-de sitter universe rst solution previous solution new cosmological black hole solution einstein-de sitter universe radiation-dominated background universe several study
