Miquel Serra Ricart, Alex Oscoz Abad, Riccardo Scarpa, Carina Fian
E. Falco (Harvard-Smithsonian Center for Astrophysics, USA), E. Simonneau (IAP, France), L. Popovic, (Obs. Astronómico Belgrado, Yugoslavia), R. Gil-Merino (Univ. Cantabria, Spain), C.S. Kochanek (The Ohio State University, USA), V. Motta (Univ. Valparaiso, Chile), P. Gómez (ESAC, Spain); T. Mediavilla, O. Ariza (UCA, Spain), C. González-Morcillo (UCLM, Spain), J. Jiménez (UGR, Spain).
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.
Optical and X-ray microlensing data from 24 gravitationally lensed quasars have been analyzed to estimate the abundance of compact objects in a very wide range of masses. It is concluded that the fraction of mass in black holes or any type of compact objects is negligible outside of the 0.05 M ⊙ M 0.45 M ⊙ mass range and that it amounts to 20% ± 5% of the total matter, in agreement with the expected masses and abundances of the stellar component. Consequently, the existence of a significant population of intermediate-mass PBHs appears to be inconsistent with current microlensing observations. Therefore, primordial massive black holes are a very unlikely source of the gravitational radiation detected by LIGO