Gravitational microlensing and the search for extrasolar planets

Master Thesis


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University of Cape Town

This project is aimed at tackling binary gravitational microlensing events. Since the early conception of gravitational lensing before Einstein’s General Theory of Relativity, physicists and astronomers of the early 18th century speculated that light, if treated as particle, can be affected by gravitational field. Gravitational Microlensing is defined as a phenomenon occurring when light coming from a distant (source) star is bent by the gravitational field of an intervening mass (lens) creating multiple image of the source which cannot be resolved. In this project, We applied a model for binary lens microlensing events. We analysed data obtained from different observatories: PLAXET, which includes SAAO, Sutherland, Canopus and Perth observatories, OGLE, Danish Telescope, LaSilla. For the observed microlensing target OGLE-2011-BLG-265, analysis of the data using the program supplied by Keith Horne, using different minimization schemes and algorithms, I found best fit model to be a binary lens with mass ratio q = 0.0042 and separation of components is found to be u = 1.034 where in this case the separation falls under an intermediate binary lens topology. Finally, the deviation from the point-source point-lens microlensing events on the light curve and small mass ratio suggested a planetary system. I also calculated the time, tp, that the source needs to cross the diameter of the planet Einstein Ring radius, which is related to the mass ratio, and is found to be 3.30 days.

Includes bibliographical references.