Séminaire Univers /
Seminar Universe

The properties of dark matter halos depend on the dark matter particle mass, formation mechanism, and possible self-interactions, enabling tests of fundamental physics through measurements of halo properties. JWST has recently surveyed a sample of 31 quadruply imaged quasars, measuring the relative magnifications among the lensed images from the compact warm dust region surrounding the background quasar. These data probe dark matter halo populations down to 10^6 solar masses, a regime where halos are too small to retain stars and emit light. I will present the first inferences on the free-streaming length of dark matter and subhalo abundance from the complete JWST lensed quasar dark matter survey. These analyses apply state-of-the-art lens modeling and analysis techniques to the largest sample of strong lenses ever assembled for a dark matter inference, yielding the most robust bound on the free-streaming length of dark matter, and the most precise measurement of subhalo abundance to date. I will also discuss applications of strong lensing to other theories, such as self-interacting dark matter, in which low-mass halos are predicted to undergo core collapse and become extremely dense, extremely efficient lenses. I will conclude by discussing how large surveys, such as Euclid, Roman, and Rubin, will discover thousands of new strong lens systems, enabling transformative dark matter science through strong lensing in the coming decade.