On Gravitational Aberrations in Stellar Images

Abstract

On the basis of a cosmological model which is fundamentally of the Friedmann expanding type with a spherically symmetric inhomogeneity superimposed, a study is made of three gravitational aberrations of purely relativistic origin observed in the images of stellar objects: (1) the "gravitational lens" effect, (2) a dispersion effect whereby a point source would produce a diffuse image, and (3) an 'apparent systematic motion of all light sources towards (or away from) the inhomogeneity. Admissable inhomogeneities in the model must satisfy PU ? 2×104 Mpc, where P is the ratio of the average density of matter within the inhomogeneity to the average density of the universe and U is its diameter in megaparsecs. The assumption is also made that the paths of light rays are described by the null-geodesic equations of the space-time under consideration.