Weinberg Institute Seminar with Daniel Gilman
Nov
4
2025
Nov
4
2025
Description
Abstract: Strong gravitational lenses enable direct inferences of the properties of dark matter halos, even if the halos are too small to retain stars and emit light. JWST has recently surveyed a sample of 31 quadruply-imaged quasars, measuring the relative magnifications (flux ratios) among lensed images from the compact warm dust region surrounding the background quasar, data which probe dark matter (sub)halo populations down to 10^6 solar masses. I will present the first inferences on dark matter properties from the complete JWST lensed quasar dark matter survey, leveraging the unified constraining power of lensed image positions, flux ratios, and extended lensed arcs to measure the free-streaming length of dark matter and the abundance of dark subhalos around strong lens systems. The results include the strongest bound on the free-streaming length of dark matter to date, and the most precise measurement of subhalo abundance around strong gravitational lenses. I will conclude by reviewing applications of strong lenses to other dark matter theories, such as self-interacting dark matter, and discuss how the order of magnitude increase in the sample size of strong lens systems provided by upcoming surveys (Euclid, Rubin, Roman) will yield further insights into the particle nature of dark matter and fundamental physics.
Audience
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