Light Curve Calculations for Triple Microlensing Systems

TL;DR

This paper introduces a novel, efficient method for calculating the magnification of finite source stars in triple microlensing systems, applicable to all multiple lens configurations, with extensions for limb-darkening effects and dense light curve sampling.

Contribution

It presents a new contour integration approach for triple lens magnification calculations, including continuous image boundary extraction and limb-darkening modeling, with publicly available code.

Findings

Effective calculation of magnifications for triple lens systems.

Extension to limb-darkened star models.

Implementation of adaptive sampling for dense light curves.

Abstract

We present a method to compute the magnification of a finite source star lensed by a triple lens system based on the image boundary (contour integration) method. We describe a new procedure to obtain continuous image boundaries from solutions of the tenth-order polynomial obtained from the lens equation. Contour integration is then applied to calculate the image areas within the image boundaries, which yields the magnification of a source with uniform brightness. We extend the magnification calculation to limb-darkened stars approximated with a linear profile. In principle, this method works for all multiple lens systems, not just triple lenses. We also include an adaptive sampling and interpolation method for calculating densely covered light curves. The C++ source code and a corresponding Python interface are publicly available.