Detection of bright multiply imaged quasars by GAIA

Bright multiply imaged quasars offer unique tools to investigate
the properties of the Universe as a whole (cosmological parameters),
the astrophysical properties of the remote galaxies acting as deflectors
(i.e. their mass, extinction law, ...) as well as the structure of
the background sources (accretion disk, central engine, etc.).

Multiply imaged quasars will represent the most easily identified
signature of lensing in GAIA observations. Several thousands of such
cases are expected with J <=20. Furthermore, the complete QSO catalog
which will be built from the GAIA observations will be very attractive
and unique in order to study QSO evolution, large scale structures,
intervening absorbers, the inertial frame, ...

The aim of this presentation is to report about a realistic estimate of
the expected number of bright multiply imaged quasars that will be detected
by GAIA.