Djuna Croon: Probing dark matter and cosmology using gravitational microlensing

Tuesday 31 Mar 2026, 13:15 → 14:00 Europe/Stockholm

FD5 (AlbaNova Main Building)

A key route to identifying the nature of dark matter is to test its predicted structure on sub-galactic scales, where different models diverge most strongly. Well-motivated scenarios predict that a fraction of the dark matter may reside in bound objects, ranging from primordial black holes to extended clumps arising in particle dark matter scenarios. Gravitational microlensing — the transient magnification of background sources — provides a direct method to detect and characterise these otherwise invisible mass concentrations. It can encode information about the mass, abundance, and spatial distribution of these structures.

In this talk, I will review how microlensing constraints already limit several dark matter scenarios and discuss the characteristic signatures expected for extended lenses. Forthcoming time-domain surveys offer a new opportunity to search for these signatures and motivate the development of new data driven methods to identify rare events. In addition, I will highlight the emerging role of microlensing in the high-magnification regions of strong gravitational lenses, which enables sensitivity to less concentrated structures. Interestingly, these measurements have novel implications for early Universe physics.

About the speaker:  Djuna Croon is an associate professor at Durham University, working at the interface of cosmology and astro-particle physics. Her research focuses on using gravitational probes of dark matter and cosmology, aiming to connect astronomical observations with fundamental physics beyond the Standard Model.

In the OKC:  Tuesday March 31st, in the CoPS A5 corridor