Gravitational Microlensing Simulation for the Large Survey Era

Abstract

Over the coming decade, new space-based and ground-based observatories promise to usher in a large survey era of gravitational microlensing science, promising a host of new exoplanet discoveries as well as high fidelity data on Galactic structure. To compliment these scientific endeavours, accurate microlensing simulations are required to inform mission parameters and analyse the unprecedented diversity of results. This work aims to provide some of the tools with which to accomplish these tasks, as well as providing a framework for further development. Primarily, the new MaBulS-2 simulation tool was developed to simulate microlensing parameters such as the event rate or optical depth and shows a higher level of agreement with empirical results from the OGLE-IV survey than has been achieved with previous work and surveys. MaBulS-2 was then employed to inform a future mission proposal by the Euclid and Roman space-based observatories aiming to characterise the free-floating planet (FFP) mass distribution via microlensing, demonstrating that such a mission could detect hundreds of Earth mass FFPs over the life time of the mission. Work was also done analysing the binary microlensing event K2- 2016-BLG-0005, found by the Kepler Space Telescope during its K2C9 microlensing campaign, which led to the discovery of a 1.10 (0.08) Jupiter mass exoplanet. This demonstrated the efficacy of using a space-based observatory at leading the discovery of exoplanets via the microlensing method. In addition to work on binary events, a raycasting simulation code was developed to analyse the magnification maps of even higher order lens systems, which was then adapted to work on a graphics processing unit, achieving increases in computation speed of two orders of magnitude, paving the way for more wide spread future applications of trinary or higher lensing calculations.

Date of Award	1 Aug 2023
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Neal Jackson (Supervisor) & Eamonn Kerins (Supervisor)