A fast algorithm for simulating light curves of stars at extreme magnification affected by microlensing

Abstract

We present a fast algorithm to produce light curves of distant stars undergoing microlensing near critical curves. The need of these type of algorithms is motivated by recent observations of microlensing events of distant stars at high redshift and at extreme magnification factors. The algorithm relies on a low-resolution computation of the deflection field due to an ensemble of microlenses near critical curves, and takes advantage of the slowly varying nature of the deflection field to infer the magnification of the unresolved images.