Miquel Serra Ricart, Alex Oscoz Abad, Riccardo Scarpa, Carina Fian
E. Falco (Harvard-Smithsonian Center for Astrophysics), E. Simonneau (IAP), L. Popovic, (Obs. Astronómico Belgrado), R. Gil-Merino (Univ. Cantabria), C.S. Kochanek (The Ohio State University), V. Motta (Univ. Valparaiso), P. Gómez (ESAC); T. Mediavilla, O. Ariza (UCA), C. González-Morcillo (UCLM), J. Jiménez (UGR).
Gravitational lenses are a powerful tool for Astrophysics and Cosmology. The goals of this project are: i) to obtain a robust determination of the Hubble constant from the time delay measured between the images of a lensed quasar; ii) to study the individual and statistical properties of dark matter condensations in lens galaxies from microlensing on the images of lensed quasars; iii) to study the unresolved structure of quasars (broad and narrow emission line and continuum emission regions) from induced variations by microlensing in the photometry of the lensed quasar images as well as in the profile of their emission lines; iv) to study the variation of dust extinction properties with redshift from the determination of extinction curves in lens galaxies; (v) to develop new numerical and statistical methods to study microlensing; (vi) to detect exoplanets through gravitational microlensing.
We have proposed to use the flux variability of lensed quasar images induced by gravitational microlensing to measure the transverse peculiar velocity of lens galaxies. Microlensing variability is caused by the relative motions of the observer, the lens galaxy, and the source. Hence, its frequency is directly related to the galaxy’s transverse peculiar velocity. Counting peak rates in the observed microlensing light curves of an ensemble of 17 lensed quasars we have obtained tentative estimates of the peculiar velocity dispersion of lens galaxies at z=0.5 of 638 km/s. Scaling at zero redshift, we derive a velocity dispersion of 491km/s, consistent with peculiar motions of nearby galaxies and with recent N-body nonlinear reconstructions of the Local Universe based on ΛCDM.