2 v 1 2 6 A pr 1 99 2 Gravitational Lensing and the Variability of G

ar X iv : a st ro - p h / 93 04 02 5 v 1 2 8 A pr 1 99 3 Lensing of invisible stars by brown dwarfs

To detect brown dwarfs in the dark galactic halo through gravitational lensing, experiments follow the luminosity of millions of stars to observe a few lensing events per year. The luminosity of a star too faint to be continuously followed can be temporarily increased above the detection limit by a lensing. The detection of these invisible stars would increase the number of events by a factor 2...

v 1 2 5 A pr 1 99 5 SWAT 95 / 70 “ FASTER THAN LIGHT ” PHOTONS IN GRAVITATIONAL FIELDS – CAUSALITY , ANOMALIES AND HORIZONS

ar X iv : h ep - p h / 99 10 51 0 v 2 2 8 O ct 1 99 9 ULB – TH 99 / 19 October 1999 Neutrino gravitational lensing

We study the lensing of neutrinos by astrophysical objects. At the difference of photons, neutrinos can cross a stellar core; as a result the lens quality improves. While Uranians alone would benefit from this effect in the Sun, similar effects could be considered for binary systems. Chercheur I. I. S. N. Directeur de recherches du F. N. R. S.

ar X iv : a st ro - p h / 99 02 37 3 v 1 2 6 Fe b 19 99 Higher Order Corrections in Gravitational Microlensing

We show that, in cosmological microlensing, corrections of order v/c ∼ ∆λ/λ, to the deflection angle of light beams from a distant source are not negligible and that all microlensing quantities should be corrected up to this order independently of the cosmological model used. keywords: microlensing, redshift, cosmology. In the last decade, gravitational lensing has become one of the most powerf...

ar X iv : a st ro - p h / 99 11 28 5 v 2 1 0 O ct 2 00 0 Weak Gravitational Lensing by the Nearby Cluster Abell 3667

We present two weak lensing reconstructions of the nearby (zcl = 0.055) merging cluster Abell 3667, based on observations taken ∼ 1 year apart under different seeing conditions. This is the lowest redshift cluster with a weak lensing mass reconstruction to date. The reproducibility of features in the two mass maps demonstrate that weak lensing studies of low-redshift clusters are feasible. Thes...