Gravitational lensing effects in a timevariable cosmological 'constant' cosmology
Abstract
A scalar field φ with a potential V(φ)is proportional to φ^α^(α > 0) has an energy density, behaving like that of a timevariable cosmological `constant', that redshifts less rapidly than the energy densities of radiation and matter, and so might contribute significantly to the present energy density. We compute, in this spatially flat cosmology, the gravitational lensing optical depth, and the expected lens redshift distribution for fixed source redshift. We find, for the values of α~4 and baryonic density parameter {OMEGA}~ 0.2 consistent with the classical cosmological tests, that the optical depth is significantly smaller than that in a constant{LAMBDA} model with the same {OMEGA}. (For {OMEGA} = 0.2 and source redshift z_s_ = 2.5, in the constant{LAMBDA} model the optical depth is a factor of ~4.3 larger than in the Einsteinde Sitter case, while in the time variable {LAMBDA} model, for α = 4, it is a factor of ~2.3 larger than in the Einsteinde Sitter model.) We also find that the redshift of the maximum of the lens distribution falls between that in the constant{LAMBDA} model and that in the Einsteinde Sitter model.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 December 1992
 DOI:
 10.1093/mnras/259.4.738
 Bibcode:
 1992MNRAS.259..738R
 Keywords:

 Cosmology;
 Equations Of Motion;
 Gravitational Lenses;
 Red Shift;
 Scalars;
 Time Dependence;
 Astrophysics