Coffee talks
Friday 27/02/2026 @ 11:30, Sala riunioni quarto piano e on-line (meet.google.com/sue-bwvk-axf)
Christopher Fassnacht (University of California, U.S.A.), "Gravitational detection of a one-million solar mass object and implications for the nature of dark matter"
Strong gravitational lensing is a powerful tool for investigating the nature of dark matter because it can not only detect objects that are too faint for standard observations (or purely dark matter), but it can provide information about the internal structure of these objects. This is important because different dark matter models differ in the number of low-mass haloes that they produce and the concentration of the haloes. I will report on the recent detection by the technique of gravitational imaging of an object that is by two orders of magnitude the lowest-mass cosmologically distant object found by this technique. The detection was made possible by VLBI observations of the system. I will then discuss what modeling of the internal structure of the object reveals.