TAPIR Seminar

Friday, November 11, 2022
2:00pm to 3:00pm
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Online and In-Person Event
Cusps of cusps: a universal model for extreme scattering events in the ISM
Dylan Jow, Graduate Student, Department of Physics, University of Toronto,


To Join via Zoom: https://caltech.zoom.us/j/89695722750

Abstract: Since the '80s, radio sources have been observed to undergo extreme scattering events (ESEs): large, frequency dependent flux modulations due to scattering off the ISM. Recently, the study of these events has undergone a revived interest due to the increase in pulsar timing data, as well as the realization that FRBs will be scattered by the same structures in the ISM. Models of the structures responsible for ESEs range from spherical-cow approximations (e.g. simple Gaussian profiles) to more exotic models (e.g. plasma shells around compact dark matter). Here we present a new model in which ESEs are produced by corrugated sheets in the ISM, which, when projected onto the plane of the sky, generically form A3 cusp catastrophes. We will argue that this model naturally explains several features in scattering data, including observations of PSR 0834+06 and the original Fiedler et al. 0954+658 ESE.  Moreover, this model is consistent with models of pulsar scintillation and does not require exotic physics to explain. We will discuss potential applications to FRB cosmology that arise from the universality of this model.

For more information, please contact JoAnn Boyd by phone at 626-395-4280 or by email at joann@caltech.edu.