Radiation in cosmological backgrounds
Abstract
Scalar and gravitational radiation in Friedmann backgrounds with positive, negative, and zero spatial curvature were studied. An attempt was also made to answer the question under what circumstances a wave propagates with or without a tail. Based on NewmanPenrose formalism, a basic wave equation for pure gravitational radiation in Friedmann background was derived. This wave equation coupled with a scalar wave equation serves as the basis of this study. After expanding the wave function in terms of spherical harmonics, a set of twodimensional wave equations. A sufficient condition under which these wave equations represent propagation of waves without a tail is then given. A set of twodimensional wave equations with closed form solutions was found. These equations, which represent characteristic propagation, could be used to test the validity of certain conjectures about the forms of wave equations which admit characteristicpropagation solutions.
 Publication:

Ph.D. Thesis
 Pub Date:
 1974
 Bibcode:
 1974PhDT.........3C
 Keywords:

 Gravitation;
 Radiation Distribution;
 Wave Equations;
 Wave Propagation;
 Problem Solving;
 Scalars;
 Spherical Harmonics;
 Space Radiation