Department of Imaging and Applied Physics Rapid Response Monitoring of Transient Radio Emission Associated With Gamma-Ray Bursts And Circinus X-1 Aquib Moin This thesis is presented for the Degree of Doctor of Philosophy (PhD) of Curtin University 2011 August ii Declaration To the best of my knowledge and belief this thesis contains no material previously published by any other person except where acknowledgement has been made. This thesis contains no material which has been accepted for the award of any other degree or diploma in any university. I hereby declare that the research work under the framework of this PhD project is conducted by the candidate and the contributions to any part of this work by others is outlined below. The papers produced during the course of this PhD have had due contributions from the co-authors. Chapter 2: Members of the Australian Long Baseline Array (LBA) team provided extensive support and assistance in setting up the e-VLBI obser- vations. Dr. Chris Phillips developed the e-VLBI monitoring system. Chapter 3: Dr. James Miller-Jones helped in the analysis and publication of the results of e-VLBI observations of Circinus X-1. Chapter 4: Dr. James Miller-Jones helped in extending the analysis of the Circinus X-1 ToO VLBI observations and contributed to produce key results related to the milliarcsecond jets associated with Circinus X-1. He also led the effort to transform the results into a paper. Dr. Cormac Reynolds and Dr. Hayley Bignall correlated the Circinus X-1 VLBI data. Chapter 5: Dr. Mark Wieringa helped with the production of GRB 100621a images. Chapter 6: Dr. Greg Taylor helped with GRB 100418a VLBI data pro- cessing. Aquib Moin August 10, 2011 Perth, Australia Acknowledgements Over the course of this PhD project, a number of people helped and sup- ported me generously in various ways. I would like to take this opportunity to extend my heartiest gratitude to them all. I am extremely grateful to my wife and family for always being there for me and finding immense happiness in what I wanted to do in my life. I would like to sincerely thank my primary supervisor, Prof. Steven Tingay for his untiring and relentless support and guidance, and for all his help at every step of my PhD work. I am extremely thankful to him for taking me through the entire experience. It was his vision and insight that laid the foundation of this project and it was due to his persistent efforts that I was able to carry out this project from start to finish. I cannot thank him enough for how much he helped and supported me and for the extra miles he went to facilitate my efforts over the entire time period I spent doing my PhD work. I am also thankful to him for making me a part of world- class initiatives such as Curtin Institute of Radio Astronomy (CIRA) and International Centre for Radio Astronomy Research (ICRAR) and enabling me to enter the exciting domain of radio astronomy. I would like to thank Dr. Chris Phillips, Dr. Cormac Reynolds, Dr. Hayley Bignall and Dr. James Miller-Jones for helping me learn various tools of the trade and teaching me various technical as well as scientific aspects of radio astronomy observations and data analysis. In the same vein, I also thank Adam Deller and Emil Lenc for being great mentors. I would also like to thank a number of people at the Australia Telescope National Facility (ATNF) of CSIRO Astronomy and Space Science (CASS) Division who have always been there to support me for my observations and who always extended a helping hand whenever required. Special mention amongst them are Dr. Phil Edwards, Dr. Tasso Tzioumis, Dr. Jamie Stevens and Dr. Robin Wark. In addition to them, I would also like to extend my gratitude to the administration and visitor services staff at ATNF CASS for their kindness and support. They have always made me feel home at the lodges at Marsfield, Parkes and Narrabri. I would like to thank the collaborators in my research, Dr. Greg Taylor, Dr. Poonam Chandra, Dr. Dale Frail and Dr. Mark Wieringa, for all their help and useful contributions to the work carried out as part of my PhD. For this PhD work, financial support was provided by the Curtin Interna- tional Postgraduate Research Scholarship (CIPRS). In addition to this, I was also awarded the ATNF graduate scholarship, which supported me for my frequent visits to ATNF observatories over the course of my PhD. I am also thankful to the administrative staff at the Department of Imaging and Applied Physics of Curtin University, at CIRA and at ICRAR, for the help and facilitation they provided me. I express my heartiest gratitude to all of those who helped, supported and facilitated me in any way in achieving the milestone of obtaining my PhD. This work would not have been possible without their sincere support. 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 explor- ing 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 pos- sibilities. 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 cam- paign 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 asso- ciated with it. The second part of this project involved a coordinated and systematic GRB detection and monitoring program, leading to the detec- tion 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. vi Contents List of Figures xi List of Tables xiii 1 Introduction 1 1.1 GoalsandObjectives. .. .. .. .. .. .. .. .. 1 1.1.1 X-ray Binary Studies: e-VLBI/VLBI observations of Circinus X-1 5 1.1.2 TheGRBafterglowprogram . 7 1.2 Motivation .................................. 9 1.3 StatementofOriginality . 10 1.4 ThesisOutline ................................ 11 2 New tools for radio astronomy in Australia: e-VLBI and the Australia Telescope Compact Array Broadband Backend 13 2.1 Introduction.................................. 13 2.2 e-VLBIinAustraliaandbeyond . 14 2.2.1 The LBA e-VLBI Network . 19 2.2.2 TheTelescopes ............................ 20 2.2.2.1 The Australia Telescope Compact Array (ATCA) . 20 2.2.2.2 Mopra............................ 22 2.2.2.3 Parkes............................ 22 2.2.2.4 Hobart ........................... 23 2.2.3 e-VLBIHardware .......................... 23 2.2.4 e-VLBISoftware ........................... 25 2.2.4.1 TheCorrelator . 25 2.2.4.2 TheRecorderServers . 27 vii CONTENTS 2.2.4.3 The Monitoring Programs . 28 2.2.5 e-VLBIOperation . .. .. .. .. .. .. .. 29 2.2.6 e-VLBIPostProcessing . 30 2.2.7 Future directions for e-VLBI: New Zealand and ASKAP . 32 2.3 CABB: Compact Array Broadband Backend . 33 2.3.1 Introduction ............................. 33 2.3.2 TheCABBSystem.......................... 34 2.3.3 CABBobservations . 36 2.4 Conclusions .................................. 37 3 e-VLBI Observations and monitoring of Circinus X-1 39 3.1 Introduction.................................. 39 3.2 ObservationsandResults . 41 3.3 Discussion................................... 46 3.3.1 The absence of a quiescent compact component . 46 3.3.2 The absence of secondary flares at apastron . 49 3.3.3 Thesizescaleoftheemission . 51 3.4 CirX-1e-VLBIinsummary. 52 4 High Resolution Imaging of Circinus X-1 53 4.1 Introduction.................................. 53 4.2 Background .................................. 54 4.3 VLBI Target of Opportunity observation of Circinus X-1 . ........ 55 4.4 Observationsanddatareduction . 56 4.5 Results..................................... 57 4.6 Discussion................................... 60 4.6.1 Morphology.............................. 60 4.6.2 Jetspeed ............................... 61 4.6.3 Openingangle ............................ 63 4.7 Summary ................................... 63 viii CONTENTS 5 Monitoring of Gamma-Ray Burst Afterglows At Radio Wavelengths 65 5.1 Introduction.................................. 65 5.2 GRBNomenclatureandTypes . 68 5.3 GRBTheory ................................. 69 5.3.1 MergingCompactObjects. 69 5.3.2 PulsarModel ............................. 71 5.3.3 Black Hole Accretion . 73 5.3.4 The Collapsar Model: GRB-Supernova connection . 74 5.3.5 GRBafterglow: Thefireballmodel . 76 5.4 RadiostudiesofGRBafterglows . 78 5.5 GRBObservations .............................. 79 5.5.1 ATCAObservations . 80 5.5.2 VLBIObservations. 84 5.6 ATCA vs EVLA afterglow observations . 88 5.7 Summary ................................... 93 6 Radio observations of GRB100418a and multi-wavelength analysis: Test of an energy injection model explaining long-lasting GRB after- glow 95 6.1 Introduction.................................. 95 6.2 Gamma-ray, X-ray and optical observations of GRB 100418a ...... 96 6.2.1 Gamma-ray observations . 97 6.2.2 X-rayobservations . 98 6.2.3 Opticalobservations . 99 6.3 Radio observations of GRB 100418a . 101 6.3.1 EVLAObservations . 101 6.3.2 ATCAObservations . 102 6.3.3 VLBAObservations . 104 6.4 Analysis and Interpretation of multi-instrument observations of GRB 100418a .................................... 110 6.5 Summary ................................... 116 ix CONTENTS 7 Conclusions 119 7.1 Recapitulation ................................ 119 7.2 CircinusX-1study .............................. 120 7.3 TheGRBafterglowstudy . 121 7.4 Futurepossibilities .