Cosmic string cusps and their application to fast radio bursts

This thesis concerns observational characteristics of two theoretical aspects of cosmic strings. The first is relativistic modification of cusps. Nambu-Goto strings generically develop cusps, regions of the string which emit coherent electromagnetic radiation when they decay. We point out that consideration of relativistic effects in the rest frame of the string cusp substantially reduces the cusp length, and therefore modifies the normally assumed power, rate, and time scale of any radiation bursts. The second is consideration of wiggly cosmic strings. Simulations imply a distribution of strings in an expanding universe develop small-scale structure called wiggles. We extend on a wiggly Polyakov formalism and show that wiggles prohibit cusp formation (barring ad-hoc fine tuning of initial conditions). We discuss these theoretical results in the context of using strings to explain fast radio bursts (FRBs). Cusp decay is a possible mechanism for sourcing FRBs. We show, however, that (1) consideration of relativistic effect leads to incompatibility with FRB data, and (2) the absence of cusps from “realistic” cosmic strings casts further doubt on the possibility of detecting cosmic strings via electromagnetic signatures.

Grantor

Department of Mathematics and Applied Mathematics

Year dc:date.issued

2018

Author dc:creator

• Gordin, Jake E. B.

Advisor dc:contributor.advisor

• Weltman, Amanda

Handle dc:identifier.uri

http://hdl.handle.net/11427/29983

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/29983