A pursuit of Fast Radio Transients with the UTMOST and Parkes radio telescopes

Abstract

Radio astronomy is currently exploring an intriguing new phase space that probes the dynamic Universe on timescales of milliseconds. Recent development of sensitive, high time resolution instruments has enabled the discovery of millisecond duration fast radio bursts (FRBs) and the erratic rotating radio transients (RRATs). A key distinguishing factor between FRBs and RRATs lies in the dispersion measure (DM) contribution along the line-of-sight through the Milky Way Galaxy's interstellar ionised plasma. The DMs of RRATs are consistent with them being a Galactic population, whereas FRBs have DMs well in excess of the expectation for a Galactic population. It is a decade since the discovery of FRBs and despite several clarifying discoveries and hypothetical explanations, no consensus has emerged regarding their origin. In this thesis I explore the possibility of using these FRBs as unique probes of the intergalactic magnetic eld (IGMF) by studying their polarisation via Faraday rotation. A robust method to obtain rotation measures (RMs) through Faraday rotation of single pulses was devised and tested on RRATs. This method enabled the first RM measurements of 18 known RRATs and has been applied to several FRBs. This thesis takes advantage of the recent upgrade to the Molonglo Observatory Synthesis Telescope (UTMOST) to conduct surveys for FRB discoveries. I performed Monte Carlo simulations of a cosmological population of FRBs to determine the detection rate at UTMOST. The UTMOST, with its large instantaneous eld-of-view and high duty cycle, is being transformed into an FRB discovery machine that will be capable of detecting an FRB a week. The null detections during the initial two surveys, which were performed as part of commissioning science, enabled estimations of upper limits of FRB rates at 843 MHz. The third survey period at UTMOST resulted in the first interferometric detections of 3 FRBs, placing their origin at beyond the ~10000 km far- eld region of the telescope, thus ruling out terrestrial radio interference as a source. Based on these detections we estimate a rate of >78 events/sky/day above a fluence of 11 Jy ms, at 843 MHz.