Physics of gravitational waves in presence of positive cosmological constant[HBNI Th132]

Abstract

Cosmological observations over past couple of decades favour our universe with a tiny positive cosmological constant. Even a tiniest value of cosmological constant, profoundly alters the asymptotic structure of space-time. This suggests that weak gravitational waves should be re-looked at as ripples on the de Sitter background.The thesis deals with different aspects weak gravitational waves on the de Sitter background. We obtain the gravitational radiation field of compactly supported source. This is given by gauge invariant part of retarded solution, expressed in terms source multi-pole moments.