Colloquium (4th July 2019): Gravitational lensing science challenges in the era of all-sky surveys

© Giorgos Vernardos

Gravitationally induced light deflections (lensing) is a phenomenon occurring at all scales when there is a sufficiently compact mass – from galaxy clusters to stars and planets – aligned with a light emitting source. The field is about to be revolutionized by new telescopes like Euclid and LSST, which will bring the number of known such objects from a few tens or hundreds to thousands. First, I present the modelling challenges of galaxy-galaxy lenses based on telescope images, in light of dark matter substructure and galaxy evolution. Then, I present the sub-case of galaxy-quasar lensing, with the quasar accretion disc being further (micro-) lensed by stellar-mass objects within the galaxy-lens.