Probing dark matter and cosmology using gravitational microlensing

Djuna Croon, IPPP Durham

Weekly Theory Seminar.

Abstract. 

Many dark matter models predict small-scale substructure, including subhaloes, boson stars, axion miniclusters, and primordial black holes. In this talk, I will discuss how gravitational microlensing serves as a powerful probe of these scenarios. Microlensing occurs when a dark matter object temporarily magnifies the light of a distant star as it passes in front of it. I will describe the characteristic signals observed in surveys, highlighting how certain mass distributions produce distinctive light curve features due to optical effects like caustics. I will explore opportunities for detecting these microlensing signatures using machine learning techniques, including real-time anomaly detection on time-series data. Finally, I will discuss how microlenses embedded in galaxy cluster macrolenses offer unique insights, which even have implications for early universe cosmology.

(The slides will be available here)

Published Jan. 5, 2026 11:37 AM - Last modified Jan. 13, 2026 2:10 PM