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 and (vi) to detect exoplanets through gravitational microlensing.
Members of the project
Highlights and results
- We have introduced a new method to measure the masses of the supermassive black holes of the quasars based on the gravitational redshift of the ultraviolet lines of the iron (UV Fe III). The calculated masses are in agreement with the estimates obtained using the virial theorem.
RXJ 0921+4529: A Binary Quasar or a Gravitational Lens?
We report the new spectroscopic observations of the gravitational lens RXJ 021+4529 with the multi-mode focal reducer SCORPIO of the SAO RAS 6 m telescope. The new spectral observations were compared with the previously observed spectra of components A and B of RXJ 0921+4529, i.e., the same components observed in different epochs. We found aPopović, L. Č. et al.
Reclassification of the nearest quasar pair candidate: SDSS J15244+3032-RXS J15244+3032
We present optical spectroscopy of the nearest quasar pair listed in the 13th edition of the Véron-Cetty & Véron catalogue, i.e. the two quasars SDSS J15244+3032 and RXS J15244+3032 (redshift z≈0.27, angular separation Δ θ≈7″, and line-of-sight velocity difference ΔV≈1900 km/s). This system would be an optimal candidate to investigate the mutualFarina, E. P. et al.
Dark Matter Mass Fraction in Lens Galaxies: New Estimates from Microlensing
We present a joint estimate of the stellar/dark matter mass fraction in lens galaxies and the average size of the accretion disk of lensed quasars based on microlensing measurements of 27 quasar image pairs seen through 19 lens galaxies. The Bayesian estimate for the fraction of the surface mass density in the form of stars is α = 0.21 ± 0.14 nearJiménez-Vicente, J. et al.