Speaker
Description
Caustic crossing events of stars in galaxies lensed by galaxy clusters can lead to extreme magnification factors, $\mu > 1000$. Several stars at cosmological redshifts, $z > 1$, have already been observed by the Hubble Space Telescope, and the number is rapidly increasing with the Jame Webb Space Telescope. The probability distribution of magnification depends on the galaxy cluster and the microlenses within the cluster. These microlenses could be a mix of baryonic stars and an astrophysical compact dark matter component such as primordial black holes. Monitoring these extreme magnification events helps reveal the underlying microlens population allowing us to constrain the dark matter abundance within the cluster. As there is no analytical method to estimate the magnification probability distribution, we have to rely on costly numerical simulations to obtain these probabilities. In this work, we have created a set of state-of-the-art simulations varying the physical parameters that control the magnification probabilities. We have obtained a semi-analytic approximation method to obtain the probability distributions bypassing the numerical simulations, saving thousands of CPU-hours and providing a physible method to constrain the dark matter abundances within these galaxy clusters.
