Exploring fundamental physics with gravitational waves
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In this dissertation I explore several topics in the field of gravitational wave astronomy. By means of introduction, I review the historical evolution of humanity's understanding of the mechanics of gravity, and the events which eventually led to the first ever detection of gravitational waves in 2015.
The first half of the thesis is dedicated to the effect which gravitational waves have on the apparent position of stars on the sky. The astrometric shift caused by a gravitational wave signal can be quantified, and precise astrometric measurements (from
The second part of the dissertation focuses on the problem of resonances in extreme mass-ratio in-spirals (EMRIs). These events are prime candidates for GW detection in the millihertz band (by detectors like LISA), and involve a stellar mass black hole (or a similar compact object) merging with a supermassive black hole. Properties of the trajectory of the lighter body are well known, however little is known about the behaviour of such systems during resonance of the radial and polar motions. Two existing models for this behaviour are described: the instantaneous frequency approach (developed by Gair, Bender, and Yunes) and the two timescales approach (proposed by Flanagan and Hinderer). Both methods depend on exact treatment of the gravitational self-force, which is currently not available. The results of Gair, Bender, and Yunes are extended to higher-order in the on-resonance flux modification, and the instantaneous frequency approach is confirmed to be a valid treatment of this problem. The algorithm for finding higher-order solutions is described, and further directions for extending this research are proposed.
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Lasenby, Anthony
Gair, Jonathan