Showing the Variation of the Hubble Constant for Different Lens Models

Abstract

The aim of this work is to show the variation of the values of the Hubble constant which are obtained using different gravitational lens models for calculating the time delay. The work involves a brief review of the practical and theoretical difficulties encountered by researchers in this field, and a review of the relation between the gravitational potential and the time delay. Using the Fermat principle, a formula for calculating the time delay is suggested. This formula depends upon the position of the source in addition to the geometrical dimensions ofthe lens system, and the redshift of the lens.

Keywords: Gravitational lens; Hubble constant; General relativity; Time delay.