Rapid response monitoring of transient radio emission associated with gamma-ray bursts and circinus X-1

Abstract

This PhD project was aimed at carrying out comprehensive observational studies of radio sources associated with two types of transients: a) Gamma- Ray Bursts (GRBs) b) an X-ray binary system Circinus X-1, by exploring and utilising new technologies and the enhanced capabilities of radio astronomy facilities in Australia. The emergence of the electronic-Very Long Baseline Interferometry (e-VLBI) capability of the Australian Long Baseline Array (LBA) and the new broadband backend for the Australia Telescope Compact Array (ATCA) has opened up new observational possibilities. These new upgrades enabled the rapid-response, high sensitivity and high resolution observations of transient radio sources.As part of this project, the radio behaviour of the peculiar X-ray binary system, Circinus X-1, was studied by executing an unprecedented e-VLBI observation campaign aimed at tracking the system along its entire binary orbit. Following the e-VLBI campaign, Target-of-Opportunity VLBI observations of Circinus X-1 allowed for the first time the detection of milliarcsecond-scale jets associated with it. The second part of this project involved a coordinated and systematic GRB detection and monitoring program, leading to the detection of the radio afterglow of an unusual gamma-ray burst, GRB 100418a which was studied in detail in an attempt to understand the underlying physical processes associated with GRBs. This program also allowed us to build-up some observational statistics and maintain a record of southern GRBs.