Research Group "Origin and Evolution of Galaxies"

Institut d'Astrophysique de Paris

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Summary of a journal-club Date Subject Presented by 13 november 2014 Cosmological distances with strongly lensed quasars I will review the field of "quasar time delays" and its application to cosmology and I will show that it bas become a truly competitive cosmological probe thanks to systematic photometric monitoring campaigns like COSMOGRAIL (COSmological MOnitoring of GRAvItational Lenses). The recent exquisite time delay measurements in selected lensed quasars, in combination with well constrained models make it possible to infer cosmological parameters like Ho to 5% accuracy at a very low cost, without any assumption about flatness and independently of any standard candle or ruler. Frédéric Courbin Ecole Polytechnique Fédérale de Lausanne (EPFL), Suisse Image : D1 Deep Field from the Legacy Survey of the Canada-France-Hawaï Telescope (CFHTLS) TERAPIX Data Processing Center (CNRS/INSU - IAP - CEA)