Much of the lensing effects in astrophysics can be adequately
described using geometric optics, where light from a point source can be split into multiple magnified images. In coherent sources, such as pulsars, FRBs, and gravitational wave sources, wave optics can be important in describing the full lensing behavior. A full wave optics description generally requires the computation of highly oscillatory diffraction integrals, and also sacrifices the useful concept of images.
In this talk, the speaker will show that diffraction integrals can be efficiently computed using an extension of the method of steepest descent from Picard-Lefschetz theory. This novel integration scheme preserves the notion of images in the full wave description. He will also discuss some of our recent work on the potential of observing "imaginary" images using the Picard-Lefschetz framework.
BIO
Fang Xi is a final-year PhD candidate at the University of Toronto working with Prof. Ue-Li Pen. He is primarily interested in the lensing of pulsars by plasma structures in the interstellar medium, and in the local environments of pulsars. He holds a MASt in Applied Mathematics (2016) from the University of Cambridge and a BSc in Mathematics and Physics (2014) from McGill University.
Host: Renkun Kuang
