Cambridge University Press 978-1-107-18941-6 — An Introduction to Radio Astronomy 4th Edition Bernard F. Burke , Francis Graham-Smith , Peter N. Wilkinson Frontmatter More Information AN INTRODUCTION TO RADIO ASTRONOMY Fourth Edition Radio astronomy is an active and rapidly expanding field owing to advances in computing techniques, with several important new instruments on the horizon. This text provides a thorough introduction to radio astronomy and its contribution to our understanding of the Universe, bridging the gap between basic introductions and research-level treatments. It begins by covering the fundamental physics of radio techniques, before moving on to single-dish telescopes and aperture-synthesis arrays. Fully updated and extensively rewrit- ten, this Fourth Edition places greater emphasis on techniques, with a detailed discussion of interferometry in particular and an introduction to digital techniques in the appendices. The science sections have been fully revised, with new author Peter Wilkinson bringing added expertise to the sections on quasars and active galaxies. Spanning the entirety of radio astronomy, this is an engaging introduction for students and researchers approaching radio astronomy for the first time. bernard f. burke was William A. M. Burden Professor of Astrophysics, formerly of the Radio Astronomy Group of the MIT Research Laboratory of Electronics, and prin- cipal investigator at the MIT Kavli Institute for Astrophysics and Space Research. He was elected a member of the United States National Academy of Sciences in 1970 and served as AAS President from 1986 to 1988. He and Kenneth Franklin discovered that Jupiter is a source of radio waves while working at the Carnegie Institution for Science, and he was part of the six-member team credited with the discovery in 1988 of the first Einstein ring. sir francis graham-smith, frs is Emeritus Professor at the University of Manchester. He was Astronomer Royal from 1982 to 1990 and Director of Jodrell Bank Observatory between 1981 and 1988. As Director of the Royal Greenwich Observatory between 1975 and 1981, Graham-Smith instituted the UK optical observatory on La Palma. In his student days at Cambridge he made the first accurate locations of cosmic radio sources, leading to their identification. At Jodrell Bank he discovered radio emission from cosmic ray showers and continues to work on pulsars, in which he discovered the polar- ization of the radio pulses. He is a co-author of Pulsar Astronomy (Cambridge University Press, Fourth Edition 2012). peter n. wilkinson is Emeritus Professor of Radio Astronomy at the University of Manchester. He has been involved in the development of radio telescopes at Jodrell Bank Observatory since 1967, including five years spent jointly at the California Institute of Technology and the US National Radio Astronomy Observatory. In 1991 he wrote the first published paper describing the scientific rationale and outline structure of a radio interferometer array, which developed into the Square Kilometre Array (SKA) project. He is now working on a novel radio telescope to map the sky with a precision ten times better than that achieved by the discoverers of the cosmic microwave background. He is a leading member of the UK’s Newton DARA Project, which teaches radio astronomy to students in Africa in preparation for hosting part of the Square Kilometre Array. © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-1-107-18941-6 — An Introduction to Radio Astronomy 4th Edition Bernard F. Burke , Francis Graham-Smith , Peter N. Wilkinson Frontmatter More Information AN INTRODUCTION TO RADIO ASTRONOMY Fourth Edition BERNARD F. BURKE Massachusetts Institute of Technology FRANCIS GRAHAM-SMITH University of Manchester PETER N. WILKINSON University of Manchester © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-1-107-18941-6 — An Introduction to Radio Astronomy 4th Edition Bernard F. Burke , Francis Graham-Smith , Peter N. Wilkinson Frontmatter More Information University Printing House, Cambridge CB2 8BS, United Kingdom One Liberty Plaza, 20th Floor, New York, NY 10006, USA 477 Williamstown Road, Port Melbourne, VIC 3207, Australia 314-321, 3rd Floor, Plot 3, Splendor Forum, Jasola District Centre, New Delhi - 110025, India 103 Penang Road, #05-06/07, Visioncrest Commercial, Singapore 238467 Cambridge University Press is part of the University of Cambridge. It furthers the University’s mission by disseminating knowledge in the pursuit of education, learning and research at the highest international levels of excellence. www.cambridge.org Information on this title: www.cambridge.org/9781107189416 DOI: 10.1017/9781316987506 © Bernard F. Burke, Francis Graham-Smith and Peter N. Wilkinson 2019 This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 1996 Second edition 2002 Third edition 2010 Fourth edition 2019 A catalogue record for this publication is available from the British Library Library of Congress Cataloging in Publication data Names: Burke, Bernard F., 1928- author. | Graham-Smith, Francis, 1923- author. | Wilkinson, Peter N., 1946- author. Title: An introduction to radio astronomy / Bernard F. Burke (Massachusetts Institute of Technology), Francis Graham-Smith (University of Manchester), Peter N. Wilkinson (University of Manchester). Description: Fourth edition. | Cambridge, United Kingdom ; New York, NY : Cambridge University Press, 2019. | Includes bibliographical references and index. Identifiers: LCCN 2018057974 | ISBN 9781107189416 (hardback ; alk. paper) | ISBN 1107189411 (hardback ; alk. paper) Subjects: LCSH: Radio astronomy–Observations. | Radio astronomy–Methodology. Classification: LCC QB476.5 .B87 2019 | DDC 522/.682–dc23 LC record available at https://lccn.loc.gov/2018057974 ISBN 978-1-107-18941-6 Hardback Additional resources for this publication at www.cambridge.org/ira4 Cambridge University Press has no responsibility for the persistence or accuracy of URLs for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate. © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-1-107-18941-6 — An Introduction to Radio Astronomy 4th Edition Bernard F. Burke , Francis Graham-Smith , Peter N. Wilkinson Frontmatter More Information In memoriam Our dear friend and colleague Bernard Burke died on 5 August 2018. He was co-author of the first edition of this Introduction in 1996. His own introduction to radio astronomy was in 1953, with FG-S at the Carnegie Institution of Washington. Bernie was known for his deep physical understanding, his good humour, and his love of history. He was widely consulted and gave wise advice on many projects in astronomy. © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-1-107-18941-6 — An Introduction to Radio Astronomy 4th Edition Bernard F. Burke , Francis Graham-Smith , Peter N. Wilkinson Frontmatter More Information Contents Preface page xvii Part I The Emission, Propagation, and Detection of Radio Waves 1 The Role of Radio Observations in Astronomy 3 1.1 The Discovery of Cosmic Radio Waves 3 1.2 The Origins of Radio Astronomy 6 1.3 Thermal and Non-Thermal Radiation Processes 8 1.4 Radio Observations 10 1.5 The Challenge of Manmade Radio Signals 12 1.6 Further Reading 14 2 Emission and General Properties of Radio Waves 15 2.1 Electromagnetic Waves 15 2.2 Wave Polarization 17 2.2.1 The Polarization Ellipse 18 2.3 Blackbody Radiation 21 2.4 Specific Intensity and Brightness 24 2.5 Radiative Transfer 26 2.6 Free–Free Radiation 29 2.7 Synchrotron Radiation 32 2.7.1 A Power-Law Energy Distribution 36 2.7.2 Synchrotron Self-Absorption 38 2.8 Inverse Compton Scattering 39 2.9 Further Reading 40 3 Spectral Lines 41 3.1 Radio Recombination Lines 42 3.2 Hyperfine Atomic Ground-State Transitions 44 3.3 Rotational Lines 45 3.4 Degeneracy Broken by Rotation 47 3.5 Detected Lines 49 3.6 Linewidths 50 3.6.1 Line Emission and Absorption 51 vii © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-1-107-18941-6 — An Introduction to Radio Astronomy 4th Edition Bernard F. Burke , Francis Graham-Smith , Peter N. Wilkinson Frontmatter More Information viii Contents 3.7 Masers 53 3.7.1 Common Masers 56 3.8 Further Reading 57 4 Radio Wave Propagation 58 4.1 Refractive Index 58 4.1.1 Dispersion and Group Velocity 59 4.2 Faraday Rotation 60 4.3 Scintillation 62 4.4 Propagation in the Earth’s Atmosphere 65 4.5 Further Reading 68 5 The Nature of the Received Radio Signal 69 5.1 Gaussian Random Noise 69 5.2 Brightness Temperature and Flux Density 71 5.2.1 Brightness Temperatures of Astronomical Sources 75 5.3 Antenna Temperature 76 5.3.1 Adding Noise Powers 78 5.3.2 Sources of Antenna Noise 79 5.3.3 Measuring the Antenna Temperature 80 5.4 Further Reading 81 6 Radiometers 82 6.1 The Basic Radiometer 83 6.1.1 Impedance Matching and Power Transfer 83 6.1.2 Power Amplification 84 6.1.3 Bandwidth and Coherence 84 6.2 Detection and Integration 85 6.3 Post-Detection Signals 87 6.3.1 Time Series 87 6.3.2 Spectrum 89 6.3.3 Recognizing a Weak Source 90 6.4 System Noise Temperature 91 6.4.1 Receiver Temperature 91 6.4.2 Receivers for Millimetre and Sub-Millimetre Waves 93 6.4.3 System Equivalent Flux Density (SEFD) 94 6.5 Calibration of the System Noise 95 6.5.1 Receiver Noise Calibration 95 6.5.2 Secondary Methods 96 6.5.3 Relative and Absolute Calibration 97 6.6 Heterodyne Receivers 97 6.7 Tracing Noise Power through a Receiver 100 6.8 Gain Variations and Their Correction 101 6.8.1 Dicke Switched Radiometer 103 6.8.2 Correlation Radiometers 105 6.9 Digital Techniques 107 6.10 Further Reading 107 © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-1-107-18941-6 — An Introduction to Radio Astronomy 4th Edition Bernard F.