03 February 2022Séminaire – Guillaume Mahler (Durham)

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Strong lensing: Illuminating galaxies clusters and the structures behind them


The strong gravitational lensing effect is a powerful technic to study both the deflector of light and the magnified sources behind it. In this talk, I will first review mass modelling approaches of galaxy clusters and present a state-of-the-art lensing model combining at the same time deep HST imaging and large spectroscopic coverage. Such a combination allows us to have a very refined mass distribution (dark matter and baryons) of a cluster of galaxies. An analysis of a larger sample of strong lensing clusters reveals that the lensing strength has a stronger correlation with the slope of the density profile rather than the total mass itself, indicating that the details of the mass distribution are more important than the total mass for future surveys. Most recent analyses revealed the lensing properties of even smaller substructures in clusters, wandering supermassive black holes (SMBH).The second part of the talk will focus on the lensed universe. Strong lensing offers unique opportunities that have no match in blank fields, from the highly magnified galaxies at z~2, resolved by lensing down to tens of pc scales, to the high-redshift lensed luminosity function that reaches fainter and smaller sources, Finally, I will discuss how future facilities such as JWST, Rubin or Euclid combined with strong lensing will revolutionise our view of the universe in the near future.