Gravitational Lensing Bound On The Average Redshift Of Gamma Ray Bursts In Models With Evolving Lenses

Abstract

Identification of gravitationally lensed Gamma Ray Bursts (GRBs) in the BATSE 4B catalog can be used to constrain the average redshift $ < z >$ of the GRBs. In this paper we investigate the effect of evolving lenses on the $< z >$ of GRBs in different cosmological models of universe. The cosmological parameters $Ω$ and $Λ$ have an effect on the $< z >$ of GRBs. The other factor which can change the $< z >$ is the evolution of galaxies. We consider three evolutionary model of galaxies. In particular, we find that the upper limit on $< z >$ of GRBs is higher in evolving model of galaxies as compared to non-evolving models of galaxies.

23 pages,one plain LaTeX file with three postscript figures This is modified version with recent BATSE efficiency parameter and with the latest F parameter