This content has been downloaded from IOPscience. Please scroll down to see the full text.

Download details:

IP Address: 54.39.106.173

This content was downloaded on 08/07/2020 at 14:40

Please note that terms and conditions apply.

The Chandra X-ray ObservatoryExploring the high energy universe

AAS Editor in Chief

Ethan Vishniac, John Hopkins University, Maryland, US

About the program:AAS-IOP Astronomy ebooks is the official book program of the AmericanAstronomical Society (AAS), and aims to share in depth the most fascinating areasof astronomy, astrophysics, solar physics and planetary science. The programincludes publications in the following topics:

Books in the program range in level from short introductory texts on fast-movingareas, graduate and upper-level undergraduate textbooks, research monographs,and practical handbooks.

For a complete list of published and forthcoming titles, please visit iopscience.org/books/aas.

About the American Astronomical SocietyThe American Astronomical Society (aas.org), established 1899, is the majororganization of professional astronomers in North America. The membership(∼7,000) also includes physicists, mathematicians, geologists, engineers and otherswhose research interests lie within the broad spectrum of subjects now comprisingthe contemporary astronomical sciences. The mission of the Society is to enhanceand share humanity’s scientific understanding of the universe.

The Chandra X-ray ObservatoryExploring the high energy universe

Edited byBelinda Wilkes and Wallace Tucker

Center for Astrophysics | Harvard & Smithsonian, 60 Garden St., Cambridge,MA 02138, USA

IOP Publishing, Bristol, UK

ª The Smithsonian Institution in association with IOP Publishing Ltd 2020

All rights reserved. No part of this publication may be reproduced, stored in a retrieval systemor transmitted in any form or by any means, electronic, mechanical, photocopying, recordingor otherwise, without the prior permission of the publisher, or as expressly permitted by law orunder terms agreed with the appropriate rights organization. Multiple copying is permitted inaccordance with the terms of licences issued by the Copyright Licensing Agency, the CopyrightClearance Centre and other reproduction rights organizations.

Permission to make use of IOP Publishing content other than as set out above may be soughtat permissions@ioppublishing.org.

Belinda Wilkes and Wallace Tucker have asserted their right to be identified as the authors of thiswork in accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988.

Media content for this book is available from https://doi.org/10.1088/978-0-7503-2163-1.

ISBN 978-0-7503-2163-1 (ebook)ISBN 978-0-7503-2161-7 (print)ISBN 978-0-7503-2164-8 (myPrint)ISBN 978-0-7503-2162-4 (mobi)

DOI 10.1088/2514-3433/ab43dc

Version: 20191201

AAS–IOP AstronomyISSN 2514-3433 (online)ISSN 2515-141X (print)

British Library Cataloguing-in-Publication Data: A catalogue record for this book is availablefrom the British Library.

Published by IOP Publishing, wholly owned by The Institute of Physics, London

IOP Publishing, Temple Circus, Temple Way, Bristol, BS1 6HG, UK

US Office: IOP Publishing, Inc., 190 North Independence Mall West, Suite 601, Philadelphia,PA 19106, USA

For all who have dedicated years, and in many cases decades, to transforming theChandra X-ray Observatory from a dream into reality and using it to explore the

high-energy universe.

Contents

Preface xv

Acknowledgments xvi

Contributors biographies xix

Prologue 0-1References 0-18

1 Introduction 1-1

1.1 Exploring the High-energy Universe 1-1

1.2 The Chandra X-ray Observatory 1-3

1.3 Mechanisms for the Production and Absorption of X-Raysin a Cosmic Setting

1-4

1.4 Stars, Planets, and Solar System Objects 1-5

1.5 Supernovae and Their Remnants 1-8

1.6 X-Ray Binaries 1-10

1.7 X-Rays from Galaxies 1-12

1.8 Supermassive Black Holes and Active Galactic Nuclei 1-13

1.9 Groups and Clusters of Galaxies 1-16

1.10 Galaxy Cluster Cosmology 1-18

1.11 Future Missions 1-19

References 1-20

2 Chandra X-ray Observatory Overview 2-1

2.1 Description of the Chandra X-Ray Observatory “(Chandra)” 2-1

2.1.1 Launch and Orbit 2-1

2.1.2 The Spacecraft 2-2

2.1.3 High Resolution Mirror Assembly (HRMA) 2-4

2.1.4 The Advanced CCD Imaging Spectrometer, ACIS 2-5

2.1.5 The High Resolution Camera, HRC 2-5

2.1.6 Transmission Gratings: HETG, LETG 2-6

2.1.7 Anticipated Lifetime 2-7

2.2 Chandra Operations 2-9

2.2.1 The Chandra X-Ray Center (CXC) 2-9

2.2.2 Operations Control Center (OCC) 2-10

2.2.3 The Chandra Task Thread 2-10

vii

2.2.4 The Observing Program 2-12

2.2.5 Standard Data Processing (SDP) 2-14

2.2.6 Data Analysis Software (CIAO) 2-15

2.3 Archives and Science 2-16

2.3.1 The Chandra Data Archive 2-17

2.3.2 The Chandra Bibliography 2-18

2.3.3 Access to Chandra Data 2-18

2.3.4 The Legacy of the CDA 2-20

2.4 The Chandra Source Catalog 2-21

2.4.1 A Catalog with Value to All Astronomers 2-21

2.4.2 Description of the Catalog 2-22

2.4.3 Enabling Science with the Chandra Source Catalog 2-26

2.5 Chandra’s Impact on Astronomy 2-27

References 2-30

3 Mechanisms for the Production and Absorptionof Cosmic X-Rays

3-1

3.1 Introduction 3-1

3.2 Classical Radiation Processes 3-3

3.2.1 Electromagnetic Waves 3-3

3.2.2 Classical Dipole Radiation 3-5

3.2.3 Radiation from a Relativistic Charged Particle 3-6

3.3 Cyclotron and Synchrotron Radiation 3-7

3.3.1 Cyclotron Radiation 3-8

3.3.2 Synchrotron Radiation 3-8

3.4 Brief Introduction to Quantum Radiation Processes 3-11

3.4.1 Energy and Momentum of a Photon 3-11

3.4.2 Blackbody Radiation 3-13

3.4.3 The Schrödinger Equation and Fermi’s Golden Rule 3-15

3.4.4 Absorption and Emission Probabilities 3-18

3.4.5 Quantum-mechanical Dipole Approximation 3-19

3.5 Scattering of Radiation by Free Electrons 3-20

3.5.1 Kinematics of Compton Scattering 3-20

3.5.2 Thomson Scattering 3-22

3.5.3 Radiation Pressure and the Eddington Limit 3-22

3.5.4 Compton Energy Exchange in a Hot Plasma 3-23

3.5.5 Compton Scattering by Relativistic Electrons 3-27

The Chandra X-ray Observatory

viii

3.6 Bremsstrahlung 3-28

3.7 Radiative Recombination 3-31

3.8 X-Ray Line Emission 3-32

3.8.1 Timescales and Assumptions 3-32

3.8.2 Line Emission Following Collisional Excitation 3-33

3.8.3 Ionization Equilibrium and Spectrum of a Hot Plasma 3-35

3.8.4 Line Broadening 3-37

3.8.5 Charge Exchange 3-38

3.9 Photoionization and X-Ray Absorption 3-38

3.9.1 Photoionization 3-38

3.9.2 Photoionization Equilibrium 3-40

3.9.3 Absorption Lines 3-40

3.9.4 K-fluorescence Lines 3-41

References 3-42

4 X-Rays from Stars and Planetary Systems 4-1

4.1 X-Rays from Solar System Bodies 4-2

4.1.1 X-Ray Emission Mechanisms in Solar System Bodies 4-2

4.1.2 Terrestrial Planets 4-4

4.1.3 The Gas Giants 4-6

4.1.4 Minor Planets and Comets 4-10

4.2 X-Rays from Low-mass Stars 4-12

4.2.1 Properties of Stellar Coronal Emission 4-15

4.2.2 The Rotation-powered Magnetic Dynamo 4-23

4.2.3 Inference of Coronal Structure from Density Diagnostics 4-28

4.2.4 Magnetic Reconnection Flares 4-30

4.2.5 Stellar Coronal Chemical Compositions 4-32

4.2.6 The End of the Main Sequence and Beyond 4-34

4.2.7 Young Stars, Protostars, Disks, and Jets 4-36

4.3 X-Ray Studies of Exoplanet Systems 4-47

4.3.1 X-Ray Induced Atmospheric Loss 4-47

4.3.2 Star–Planet Interaction? 4-48

4.3.3 X-Rays as Probes of Exoplanet Atmospheres 4-48

4.4 X-Rays from High-mass Stars 4-49

4.4.1 Universality of the LX–Lbol Relation 4-50

4.4.2 Colliding Winds 4-53

4.4.3 The Role of Magnetism 4-56

The Chandra X-ray Observatory

ix

4.4.4 The Weak Winds Problem 4-59

4.4.5 The Mysterious X-Rays from Cepheid Variables 4-59

4.5 Intermediate-mass Stars 4-60

4.6 White Dwarfs and White Dwarf Binary Systems 4-64

4.6.1 White Dwarf Birth in Planetary Nebulae 4-65

4.6.2 Photospheric Emission 4-67

4.6.3 Cataclysmic Variables and Nova Explosions 4-69

4.7 Epilogue 4-79

References 4-80

5 Supernovae and Their Remnants 5-1

5.1 Supernovae 5-1

5.1.1 Supernova Types 5-1

5.1.2 Progenitors and Circumstellar Environments 5-4

5.1.3 Supernova 1987A 5-9

5.2 Supernova Remnants 5-10

5.2.1 Properties of SNR Shocks 5-11

5.2.2 SNR Structure 5-13

5.2.3 SNR Ejecta and Constraints on Progenitors 5-19

5.2.4 Cosmic-Ray Acceleration in SNRs 5-26

5.3 Pulsar Wind Nebulae 5-29

5.3.1 Pulsars 5-30

5.3.2 Pulsar Wind Structure 5-31

5.3.3 PWN Evolution 5-33

References 5-40

6 X-Ray Binaries 6-1

6.1 Introduction 6-1

6.1.1 X-Ray Binaries at the Extremes of Flux 6-1

6.2 X-Ray Binaries in Quiescence 6-2

6.2.1 Black Hole Candidates versus Neutron Stars 6-2

6.2.2 Jet and Advection-dominated States of Black Hole Candidates 6-3

6.2.3 Quiescent and Cooling Neutron Stars 6-6

6.2.4 Transitional Neutron Star Systems 6-11

6.3 X-Ray Binaries in Action 6-12

6.3.1 Probes of the Inner, Relativistic Accretion Flow 6-12

The Chandra X-ray Observatory

x

6.3.2 Outer Disk Structure 6-14

6.3.3 Wind Structure, Driving Mechanisms, and Transitionsto Jet-dominated States

6-15

6.4 Circumbinary and Interstellar Medium 6-20

6.4.1 Probes of Stellar Wind Structure 6-21

6.4.2 Interstellar Medium 6-24

6.4.3 Dust-scattering Halos 6-26

6.5 Extreme Physics Systems 6-28

6.5.1 Ultraluminous X-Ray Sources 6-29

6.5.2 Multimessenger Systems—GW 170817 6-34

6.6 Summary 6-38

References 6-38

7 X-Rays from Galaxies 7-1

7.1 Introduction 7-1

7.2 X-Ray Binary Populations 7-2

7.2.1 The XRB X-Ray Luminosity Functions and ScalingLaws in the Near Universe

7-5

7.2.2 The Redshift Evolution of the XRB Emission 7-8

7.2.3 The Spatial Distributions of the XRBs 7-8

7.3 Hot ISM and Halos 7-11

7.3.1 The Hot ISM of Star-forming Galaxies and Mergers 7-12

7.3.2 The Hot ISM of Early-type (Elliptical and S0) Galaxies 7-16

7.3.3 Scaling Relations of ETGs 7-17

7.3.4 Constraints on the Binding Mass of ETGs 7-20

7.3.5 Metal Abundances of the Hot Halos of ETGs 7-22

7.3.6 ETGs at Higher Redshift 7-23

7.4 Nuclear BHs and AGNs 7-25

7.4.1 Hidden AGNs in Normal Galaxies 7-25

7.4.2 AGNs in Merging Galaxies 7-27

7.5 AGN–Galaxy Interaction in Nearby Spiral Galaxies 7-28

7.5.1 Methods 7-29

7.5.2 The Soft (E < 2.5 keV) X-Ray Emission ofAGN Photoionization Cones and Soft X-RayConstraints on AGN Feedback

7-31

7.5.3 A Chandra Surprise: The Extended Hard andFe Kα Emission of AGNs

7-34

The Chandra X-ray Observatory

xi

7.5.4 Imaging the Obscuring Torus 7-35

7.5.5 Is the Torus Porous? 7-36

7.6 Looking Forward 7-37

References 7-38

8 Supermassive Black Holes (Active Galactic Nuclei) 8-1

8.1 Observing SMBHs 8-1

8.2 Accretion Flow onto SMBH 8-3

8.2.1 Modes of Accretion 8-3

8.2.2 Bondi Radius and Inflow Rates 8-5

8.2.3 SMBH in the Galactic Center 8-6

8.2.4 Quasars and the Eddington limit 8-8

8.3 SMBH Formation and Growth 8-10

8.4 AGN Structure 8-11

8.4.1 Variability and X-Ray Reverberation 8-13

8.4.2 Microlensing 8-13

8.4.3 Imaging of the Torus and X-Ray-scattering Region 8-15

8.4.4 Resolving Layers of Ionized Gas with High-resolutionX-Ray Spectra

8-15

8.5 Jets and Extended Radio Structures 8-17

8.5.1 Resolving X-Ray Jets—Knots and Hotspots 8-19

8.5.2 Jet X-Ray Radiation Processes 8-19

8.5.3 Variability and Proper Motions of Resolved X-Ray Jets 8-20

8.5.4 The Impact of Jets on the ISM 8-22

8.6 Finding Supermassive Black Holes in X-Ray Surveys 8-27

8.6.1 X-Ray Surveys Overview 8-27

8.6.2 Populations Studies: The Discoveries in X-Ray Surveys 8-29

8.6.3 SMBH and Host Galaxy Coevolution 8-34

8.6.4 X-Ray Luminosity Function 8-35

8.6.5 Probing Lower-luminosity Populations withStacking Analysis

8-38

8.6.6 The High-rdshift Universe as Seen in Surveys 8-39

8.6.7 Resolving the Cosmic X-Ray Background 8-42

8.7 Final Remarks 8-43

References 8-43

The Chandra X-ray Observatory

xii

9 Groups and Clusters of Galaxies 9-1

9.1 Introduction 9-1

9.2 Basic Properties of Clusters and the ICM 9-1

9.3 AGN Feedback in Groups and Clusters 9-2

9.3.1 The Need for Feedback 9-2

9.3.2 The Case for Feedback 9-3

9.3.3 Cavity Calorimetry 9-6

9.3.4 AGN Shocks 9-10

9.3.5 Feeding the AGN 9-13

9.3.6 AGN Heating 9-17

9.3.7 Growth of Cool Cores 9-19

9.3.8 Synopsis 9-20

9.4 Atmospheric Dynamics 9-20

9.4.1 Merger Cold Fronts 9-21

9.4.2 Sloshing Cold Fronts 9-23

9.4.3 Merger Shocks 9-27

9.4.4 Turbulence in the ICM 9-31

9.4.5 Large-scale Abundance Distribution 9-34

9.4.6 Galaxy Stripping 9-34

9.5 The Future 9-38

References 9-39

10 Galaxy Cluster Cosmology 10-1

10.1 Introduction 10-1

10.2 Cosmology with the fgas Test 10-5

10.3 Cosmology with Cluster Number Counts 10-9

10.4 Dark Matter 10-18

10.4.1 Constraints on Dark Matter from Merging Clusters 10-18

10.4.2 Constraints on Dark Matter fromDynamically Relaxed Clusters

10-19

10.4.3 Constraints on Dark Matter fromX-Ray Spectral-line Searches

10-20

10.5 Measurements of the Hubble Constant 10-21

10.6 Other Fundamental Physics 10-21

10.6.1 Gravity 10-21

10.6.2 Neutrinos 10-23

10.6.3 Inflation 10-24

The Chandra X-ray Observatory

xiii

10.7 Conclusions and Future Prospects 10-26

References 10-28

11 Future X-Ray Missions 11-1

11.1 Approved Missions 11-2

11.1.1 Spektr-RG/SRG 11-2

11.1.2 The X-Ray Imaging and Spectroscopy Mission 11-4

11.1.3 The Imaging X-Ray Polarimetry Explorer 11-5

11.1.4 The Advanced Telescope for HighENergy Astrophysics (Athena)

11-5

11.2 Possible Future US-based X-Ray Missions 11-7

11.2.1 The Lynx X-Ray Observatory 11-7

11.2.2 Arcus 11-8

11.2.3 Advanced X-Ray Imaging Satellite 11-9

11.2.4 The High-Energy X-Ray Probe 11-10

11.2.5 The Spectroscopic Time-Resolving Observatoryfor Broadband Energy X-Rays

11-10

References 11-11

The Chandra X-ray Observatory

xiv

Preface

The development of X-ray telescopes, culminating in the Chandra X-rayObservatory, is one of the great success stories of modern science and technology.Less than six decades ago, Riccardo Giacconi and his colleagues discovered the firstextrasolar X-source. Only 37 years later—Riccardo always insisted it could havebeen much sooner!—Chandra was launched. As the first, and to date only, X-raytelescope capable of producing subarcsecond images, a critical feature for multi-wavelength investigations with optical, infrared, and radio telescopes, Chandrarevolutionized the field overnight. This was made clear with the discovery of thelong-sought neutron star in the center of the Cassiopeia A supernova remnant inChandraʼs first-light image.

Twenty years after launch, Chandra continues to make discoveries, and it hasfirmly established its role as one of the most versatile and powerful tools forexploring the universe and the fundamental laws that govern our existence. Chandragives us a spectacular view of the hot, high-energy regions of the universe, reachingdown to faint sources that produce only one photon every 13 days, 10 orders ofmagnitude fainter than the brightest X-ray source, Sco X-1.

Chandra observations have probed the geometry of spacetime around a blackhole, unveiled the role of accreting supermassive black holes in influencing theevolution of the most massive galaxies, provided some of the best evidence yet forthe existence of dark matter, and independently confirmed the presence of darkenergy. Chandra has tracked the dispersal of heavy elements by supernovae and hasmeasured the flaring rates of young Sun-like stars with implications for theformation of planets. With Chandra observations, it is also possible to do researchin fundamental physics, by testing the basic principles in domains not accessibleon Earth.

This book is intended to be an introduction to a fertile and exciting field ofresearch, as well as a progress report that captures the depth and breadth of theadvances and discoveries made in first two decades of Chandra.

With this goal in mind, we have assembled contributions from a “stellar” team ofscientists. They include Jeremy J. Drake, who discusses X-rays from stars andplanetary systems; Patrick Slane on supernovae and their remnants; Michael A.Nowak and Dom J. Walton on X-ray binaries; Giuseppina Fabbiano on X-raysfrom galaxies; Aneta Siemiginowska and Francesca Civano on supermassive blackholes; Paul Nulsen and Brian McNamara on groups and clusters of galaxies; andfinally, Steven W. Allen and Adam B. Mantz on galaxy cluster cosmology. RafaeleD’Abrusco and Rafael Martinez-Galarza were coauthors with one of us (B.W.) ofan overview of Chandra and its operations, and in the prologue, Harvey Tananbaumand Martin C. Weisskopf provide a unique perspective from two scientists whohave, between them, 85 years of experience with Chandra, most of the time in projectleadership positions.

xv

Acknowledgments

We are extremely grateful to the scientists, engineers and staff of the Chandra X-rayCenter and the NASA Project Office at Marshall Space Flight Center, withoutwhose expertise and dedication the work described in this book would not have beenpossible. We are also deeply indebted to the many people who supported us as weprepared the manuscript. These include our IoP editor Leigh Jenkins, for hercontinuous support and patient responses to our many questions throughout thislong process; Peter Edmonds for reviewing all of the figures and obtainingpermissions for reproduction as needed; Evan Tingle for working with the variousauthors on electronic figures; and Chris Ingle at IoP who, in consultation with Evan,prepared interactive electronic figures of various kinds. In addition to variousreviews by the co-chapter-authors, all chapters were reviewed by experts in eachtopic: Dan Schwartz, Jonathan McDowell, Antonella Fruscione, Randall Smith,Vinay Kashyap, Dan Patnaude, Jack Steiner, Dong-Woo Kim, Martin Elvis, ScottRandall, and Bill Forman, all of whom we wish to thank.

R.A., F.C., J.J.D., G.F., R.M.G., P.E.J.N., A.S., P.S., H.T., W.K.T., and B.J.W.acknowledge the support of NASA contract NAS8-03060.

Chapter 4Thanks to M. Corcoran, W. Dunn, P. Edmonds, V. Kashyap, B. Snios, W. Tucker,and B. Wargelin for helpful comments, corrections, and suggestions.

Chapter 6M.A.N. would like to thank the numerous colleagues who have been influential indriving his thinking about many of these topics, especially Jörn Wilms, KatjaPottschmidt, Christopher Reynolds, Julia Lee, Daryl Haggard, and Sera Markoff.M.A.N. would also like to thank the help of the many young scientists who he hadthe privilege to work with when they were graduate students and/or postdocsworking with Chandra observations and who have continued to make significantcontributions to the science areas discussed above, especially Lia Corrales, VictoriaGrinberg, Sebastian Heinz, Li Ji, Jon Miller, Joseph Neilsen, and Rudy Wijnands.M.A.N. thanks Jack Steiner for giving feedback on a draft of the manuscript.Finally, M.A.N. would like to give special thanks to the High Energy TransmissionGrating Spectrometer team at the Massachusetts Institute of Technology ChandraX-ray Science Center: Glenn Allen, John Davis, Dan Dewey, David Heunemoerder,John Houck, Katherine Flanagan, Herman Marshall, Michael Noble, NorbertSchulz, Michael Wise, and especially Claude Canizares, the Principal Investigator ofthe HETGS. D.J.W. is supported by STFC through an Ernest Rutherford fellow-ship and would like to thank Felix Fürst, Matt Middleton, Matteo Bachetti, MurrayBrightman, Marianne Heida, and Ciro Pinto for their continued collaboration, aswell as Andy Fabian, Fiona Harrison, and Daniel Stern for their excellent mentor-ship over the years.

xvi

Chapter 7A large part of this chapter was written at the Aspen Center for Physics (ACP) andbenefited from discussions with other visitors at the Center. The ACP is supportedby National Science Foundation grant PHY-1607611. We thank Martin Elvis,Alessandro Paggi, and Andreas Zezas for input and comments on the manuscript.

Chapter 8We thank F. Fornasini, M. Jones, M. Elvis, G. Fabbiano, B. Snios, R. Hickox, andB. Wilkes for comments that improved our chapter. We are grateful toJ. Comerford, S. Marchesi, H.R. Russell, M. Sobolewska, B. Snios, G. Lanzuisi,and F. Vito for providing updated figures, and to S. LaMassa and R. Canning forsharing unpublished flux sensitivity curves for the Stripe82 and CATS surveys. Wealso thank all of the authors that allowed the use of their proprietary graphics in thischapter.

Chapter 9We thank Scott Randall for providing comments, and Helen Russell and JulieHlavacek-Larrondo for providing figures. We also wish to thank Elke Roediger andAlex Sheardown for creating the movie associated with Figure 9.13.

Chapter 10Parts of this discussion were adapted from “Cosmological Parameters fromObservations of Galaxy Clusters,” co-written with Gus Evrard and published inthe Annual Review of Astronomy & Astrophysics (Allen et al. 2011). We are gratefulto many colleagues for their valuable insights and contributions to the workpresented here, including Mark Allen, Doug Applegate, Camille Avestruz, NickBattaglia, Lucie Baumount, Brad Benson, Lindsey Bleem, Stefano Borgani, MarusaBradač Patricia Burchat, David Burke, Rebecca Canning, Doug Clowe, HaraldEbeling, Steven Ehlert, Andy Fabian, Daniel Gruen, Pat Henry, RicardoHerbonnet, Stefan Hilbert, Julie Hlavacek-Larrondo, Ashley King, Patrick Kelly,Andrey Kravtsov, Anja von der Linden, Michael McDonald, Glenn Morris, JustinMyles, Daisuke Nagai, Emil Noordeh, Saul Perlmutter, David Rapetti, EduardoRozo, Eli Rykoff, Robert Schmidt, Tim Schrabback, Neelima Sehgal, SaraShandera, Aurora Simionescu, Ondrej Urban, Alexey Vikhlinin, Risa Wechsler,Norbert Werner, Adam Wright, and Irina Zhuravleva. S.W.A. is supported in partby the US Department of Energy under contract No. DE-AC02-76SF00515.A.B.M. is supported by the Kavli Institute for Particle Astrophysics andCosmology at Stanford. S.W.A. acknowledges the hospitality of the Institute ofAstronomy, Cambridge, UK, during the completion of this review.

Chapter 11I would like to thank those who have provided information and figures for thevarious projects described in this chapter, in particular Paul Nandra (Athena),

The Chandra X-ray Observatory

xvii

Alexey Vikhlinin (Lynx), Grant Tremblay (Lynx), Peter Predehl (eROSITA), MikailPavlinsky (SRG), Paul Ray (STROBE-X), Randall Smith (Arcus), RichardMushotzky (AXIS), Maxim Markevitch (AXIS), Laura Brenneman (HEX-P),Rob Petre (XRISM), and Makoto Tashiro (XRISM).

ReferenceAllen, S. W., Evrard, A. E., & Mantz, A. B. 2011, ARAA, 49, 409

The Chandra X-ray Observatory

xviii

Contributors biographies

Harvey Tananbaum

Dr. Harvey Tananbaum is a Senior Astrophysicist at theSmithsonian Astrophysical Observatory (SAO) in Cambridge,Massachusetts. He received his BA in mathematics and physicsfrom Yale University in 1964, and his PhD in physics from MIT in1968. His thesis research studied a mysterious, highly variablecosmic X-ray source. Later, observations with Uhuru—the firstsatellite dedicated to X-ray astronomy—along with ground-based

optical and radio data were instrumental in showing that this source, Cygnus X-1,was powered by matter falling into a black hole. Dr. Tananbaum directed SAO’sHigh Energy Astrophysics Division from 1981 through 1993. He served as ProjectScientist for Uhuru; as Scientific Program Manager for the HEAO-2/Einsteinmission, the first imaging telescope for extra-solar X-ray astronomy; and asPrincipal Investigator and Director of the Einstein Data Center. In 1976, he andRiccardo Giacconi led the team which proposed to NASA to initiate the study anddesign of a large, long-lived X-ray telescope that was launched in 1999, as theChandra X-Ray Observatory. He organized and led the team which was selectedcompetitively in 1991 to develop and operate the entity now known as the ChandraX-ray Center, for which he served as Director from 1991–2014. Dr. Tananbaumreceived the NASA Exceptional Scientific Achievement Medal, the NASA PublicService Award, and the NASA Medal for Outstanding Leadership. In 2004, he andDr. Martin Weisskopf were awarded the Bruno Rossi prize of the High EnergyAstrophysics Division of the American Astronomical Society, for “...vision,dedication, and leadership in the development, testing, and operation of the ChandraX-ray Observatory.” In 2005, Dr. Tananbaum was elected to the National Academyof Sciences.

Martin Weisskopf

Dr. Martin C. Weisskopf is Project Scientist for NASA’s ChandraX-ray Observatory, Principal Investigator of the Imaging X-rayPolarimetry Explorer (IXPE), and Chief Scientist for X-rayAstronomy at Marshall Space Flight Center (MSFC), where hebegan his NASA career in 1977. Weisskopf was previously anassistant professor at Columbia University and performed manypioneering experiments in X-ray astronomy—particularly in X-ray

polarimetry. He earned a bachelor’s degree in physics from Oberlin College and adoctorate in physics from Brandeis University. Weisskopf is author or co-author ofover 350 publications—including refereed journal articles, book articles,monographs and papers in conference proceedings and has received numerous

xix

honors—including the Rossi Prize of the High Energy Astrophysics Division of theAmerican Astronomical Society (shared with Dr. H. Tananbaum). He is also aFellow of both the American Physical Society and the SPIE.

Wallace Tucker

Dr. Wallace Tucker served as the science spokesperson for theChandra X-ray Center at the Center for Astrophysics | Harvard &Smithsonian for 20 years. In that capacity he worked closely withand contributed written material for the Chandra Communications& Public Engagement program, which has received recognition forits projects and digital content through two internationalcommunication awards and numerous US digital awards. Tucker

received a BS in Mathematics and a MS in Physics from the University ofOklahoma, and PhD in Physics from the University of California, San Diego in1966. He was a research associate at Cornell University, and an Assistant Professorof Space Science at Rice University, before moving to American Science &Engineering (AS&E) to become the head of the theoretical astrophysics group.From 1972 until 1996 he worked as a consultant for AS&E and held positions at theSmithsonian Astrophysical Observatory, United States International University,University of California, Irvine, and University of California, San Diego beforejoining the Chandra X-ray Center. He is a member of the American AstronomicalSociety, the American Association for the Advancement of Science, and theInternational Astronomical Union. He is the author or co-author of six books onastronomy for the general reader including The X-ray Universe with RiccardoGiacconi, and two textbooks, Radiative Processes in Astrophysics and HeathPhysical Science. He has authored or co-authored numerous scientific and populararticles on astrophysics. He has also written three prize-winning stage plays, one ofwhich was published in an anthology of American Indian plays, and is active in landconservation, having co-founded the Fallbrook Land Conservancy, which haspreserved more than 2,000 acres of open space.

Belinda Wilkes

Dr. Belinda Wilkes is a Senior Astrophysicist at the Center forAstrophysics | Harvard & Smithsonian. She has served as Directorof the Chandra X-ray Center, which operates the Chandra X-rayObservatory on contract with NASA, since 2014. Dr. Wilkesreceived her BSc in Astronomy and Physics from the University ofSt. Andrews, Scotland in 1978 and her PhD in Astronomy from theUniversity of Cambridge, England, in 1982. She spent two years at

the University of Arizona’s Steward Observatory as a NATO postdoctoral fellow,and moved to CfA’s High Energy Astrophysics Division in 1984. She is a Fellow of

The Chandra X-ray Observatory

xx

the Royal Astronomical Society and of the Cambridge Philosophical Society, and amember of the American Astronomical Society, the International AstronomicalUnion, the American Physical Society and the American Association for theAdvancement of Science. She has received numerous Smithsonian Institutionawards including the Exceptional Accomplishment Awards and NASA GroupAchievement Awards, and a NASA MSFC Director’s Commendation. In 2018 shewas elected an Honorary Fellow of Jesus College, Cambridge University, England.Her research involves X-ray and multi-wavelength studies of active galaxies. She isauthor or co-author of over 460 publications, including refereed science papers,book chapters, papers in conference proceedings, abstracts, white papers, author oreditor of several books, and of science articles in the public media.

Raffaele D’Abrusco

Dr. Raffaele D’Abrusco is a staff astrophysicist at the Center forAstrophysics | Harvard & Smithsonian and is responsible for thearchive operations team of the Chandra X-ray Observatory. Heworks on classification of high-energy sources, evolution of galaxiesthrough the spatial distribution of globular clusters and theapplication of data mining tools to large/complex astronomicaldatasets. He was educated at the University of Naples “Federico II”

(Italy) as both an undergraduate (2004) and postgraduate (2007). Before joining theCXC, he has held postdoctoral appointments at the University of Naples, Universityof Padua and the High Energy Astrophysics Division at the CfA.

Rafael Martínez-Galarza

Dr. Rafael Martínez-Galarza is an astrophysicist at the SmithsonianAstrophysical Observatory (SAO) and the deputy end-to-endscientist for the Chandra X-ray Center (CXC) Data Systems, wherehe has had a significant participation in the release of the ChandraSource Catalog 2.0. His research focuses onmulti-wavelength studies of star-forming galaxies, and on the use ofmachine learning techniques for the exploration of large

astronomical datasets. Before joining the CXC, he was a postdoctoral fellow at SAOand a teaching fellow at Harvard University’s Institute for Applied ComputationalScience, where he taught stochastic optimization and machine learning. He hasworked as a calibration scientist for the Mid-Infrared Instrument for the JamesWebb Space Telescope and is currently a member of the LSST science collaborationin transients and variable stars. He holds a PhD in astronomy from LeidenUniversity in the Netherlands.

The Chandra X-ray Observatory

xxi

Jeremy Drake

Dr. Jeremy Drake is a Senior Astrophysicist at the SmithsonianAstrophysical Observatory of the Harvard-Smithsonian Center forAstrophysics in Cambridge, Massachusetts, USA. He graduatedwith a DPhil degree in 1989 from the University of Oxford, and wassubsequently awarded a NATO Postdoctoral Fellowship to work atthe University of Texas at Austin, USA, on high-resolutionspectroscopy of stars. A subsequent move to the University of

California, Berkely, saw Drake move higher up in the stellar atmosphere to studystellar coronae using what was to be the newly-launched NASA Extreme UltravioletExplorer (EUVE). This provided a natural platform to move to higher energies still,and at the end of 1995 he moved to SAO to work on the Advanced X-rayAstrophysics Facility, subsequently re-named the Chandra X-ray Observatory. Hestudies the high-energy aspects of stellar physics and how they impact star andplanet formation, stellar evolution, and planetary radiation environments.

Patrick Slane

Dr. Patrick Slane is a Senior Astrophysicist at the Center forAstrophysics | Harvard & Smithsonian. His research centers onhigh energy astrophysics, with particular concentration onsupernova remnants, young neutron stars, and pulsar winds. Hecompleted his undergraduate studies at the University of Wisconsin—Whitewater, a masters degree in mathematics at the University ofWisconsin—Milwaukee, and his PhD in physics at the University

of Wisconsin—Madison. He has served the scientific community as a member of theExecutive Committees for the High Energy Astrophysics Division of the AAS andthe Division of Astrophysics of the APS. He has been the recipient of numerousNASA Group Achievement awards and Smithsonian Superior Accomplishmentawards, and is an elected Fellow of the APS. He is currently the Assistant Directorfor Science at the Chandra X-ray Center where he also leads the Science MissionPlanning Team for NASA’s Chandra X-ray Observatory.

Michael Nowak

Dr. Michael Nowak is a research professor in physics at WashingtonUniversity in St. Louis. He studied physics at the MassachusettsInstitute of Technology (MIT; SB 1987) and Stanford University(MS 1988, PhD 1992), and held postdoctoral positions at theCanadian Institute of Theoretical Astrophysics and the Universityof Colorado, before becoming a research scientist for the ChandraX-ray Observatory at MIT (2001–2018). He studies the high energy

The Chandra X-ray Observatory

xxii

astrophysics of stellar mass black holes and neutron stars in our own galaxy, as wellas supermassive black holes in the centers of our own and other galaxies. He hasbeen especially interested in using X-ray variability and spectroscopy to proberelativistic effects in these systems.

Dominic Walton

Dr. Dominic Walton is a senior research fellow in astrophysics at theUniversity of Cambridge, UK. He has spent most of his careerworking on a wide variety of different accreting systems, includingGalactic X-ray binaries, ultraluminous X-ray sources and activegalactic nuclei, focusing primarily on the study of their emission inthe X-ray band by utilizing a variety of different space-basedfacilities. Educated at Durham University (undergraduate, 2008)

and the University of Cambridge (PhD, 2012), he has also previously held researchpositions at the California Institute of Technology, working with the NuSTAR X-ray observatory, and NASA’s Jet Propulsion Laboratory, having won a NASApostdoctoral research fellowship. He is currently supported by STFC after beingawarded an Ernest Rutherford fellowship.

Giuseppina Fabbiano

Dr. Giuseppina (Pepi) Fabbiano is a Senior Astrophysicist at theSmithsonian Astrophysical Observatory (Center for Astrophysics |Harvard & Smithsonian, Cambridge MA), which she joined in1975. A native of Italy, she has worked in X-ray Astronomy sinceobtaining her Doctorate in Physics from the University of Palermo(Italy) in 1973. She has been instrumental in establishing the field ofX-ray studies of galaxies. Over the years, she has studied the

different components of the X-ray emission of the Milky Way and external galaxies,including neutron stars and black holes in binary systems, supernova remnants, thehot interstellar medium and nuclear massive black holes. She uses X-rayobservations, together with data throughout the observable spectrum, to investigatethe joint evolution of galaxies and black holes in the universe. She is the author ofover 270 refereed papers in major scientific journals, including two invited reviews inthe Annual Review of Astronomy and Astrophysics, and several reviews and bookcontributions. Throughout her career, Fabbiano has been involved in the operationsand data management of major NASA X-ray observatories, and is presently theHead of the Chandra X-ray Observatory Data Systems Division. She has served inseveral national and international scientific and data management committees. Sheis a member of the executive committee of the International Virtual ObservatoryAlliance, an organization whose purpose is to foster standards for datainteroperability throughout astronomy. She is also a member of the board of theAspen Center for Physics.

The Chandra X-ray Observatory

xxiii

Aneta Siemiginowska

Dr. Aneta Siemiginowska is a Senior Astrophysicist in the HighEnergy Astrophysics Division of the Center for Astrophysics |Harvard and Smithsonian, and a member of the Science DataSystem team at the Chandra X-ray Center. She studied at theUniversity of Warsaw (MS 1985), and Nicolaus CopernicusAstronomical Center in Warsaw (PhD 1991). She has worked inboth theoretical and observational aspects of X-ray astronomy with

interests in extragalactic radio sources, quasars, powerful jets and statisticalmethods. She has discovered several hundred kiloparsec long relativistic X-ray jetsassociated with distant quasars and initiated early studies of young radio sources inX-rays with Chandra. In addition to X-ray research, she is also a founding memberof the International CHASC AstroStatistics Collaboration promotingcommunication and algorithm development between astrophysicists andstatisticians. She served as Chair of the American Astronomical Society WorkingGroup on Astroinformatics and Astrostatistics (2013-2019), promoting awareness ofthe applications of advanced computer science, statistics and allied branches ofapplied mathematics to further the goals of astronomical and astrophysicalresearch.

Francesca Civano

Dr. Francesca Civano is an Astrophysicist at the Center forAstrophysics | Harvard & Smithsonian, where she is the DeputyManager for Data Processing at NASA’s Chandra X-rayObservatory and also researches black holes and galaxies. Sheobtained her PhD at the Bologna University in 2007. She was apostdoctoral fellow at the Harvard-Smithsonian center forAstrophysics from 2007–2012, a research associate at Dartmouth

College and Yale University from 2012–2016. Dr. Civano is the PI of the ChandraCOSMOS Legacy survey, a 2.8 million seconds program to observe the CosmicEvolution Survey field with Chandra and learn about black hole and galaxyco-evolution. She also led a 3.1 million seconds survey of the same COSMOS fieldwith NASA’s NuSTAR, and was just awarded 585k seconds to observe the NorthEcliptic Pole field. Her research interests include the interplay and evolution ofgalaxies and the active supermassive black holes at their center (and not!) using datafrom all the electromagnetic spectrum. Dr. Civano is deeply involved in the secondrelease of the Chandra Source Catalog.

The Chandra X-ray Observatory

xxiv

Paul Nulsen

Dr. Paul Nulsen is a Senior Astrophysicist at the SmithsonianAstrophysical Observatory in Cambridge, Massachusetts, where hemanages operations for the Chandra High Resolution Camera. Hisresearch centres on galaxy groups and clusters, particularly X-rayobservations and theory of the physical processes affecting their hotatmospheres. Following a BSc University of Western Australia(1975) and PhD at the University of Cambridge (1980), he has held

positions at the Institute of Astronomy, Cambridge, the Australian NationalUniversity, the University of Wollongong and the Harvard-Smithsonian Center forAstrophysics.

Brian McNamara

Dr. Brian McNamara is Professor, Department Chair, andUniversity Research Chair in Physics & Astronomy at theUniversity of Waterloo, in Ontario, Canada. He is an Affiliate ofthe Perimeter Institute for Theoretical Physics, former visitingmember of the Harvard-Smithsonian Center for Astrophysics, andformer Director of the Guelph-Waterloo Physics Institute. Afterreceiving a PhD at the University of Virginia in 1991, McNamara

took a postdoctoral fellowship at the Kapteyn Laboratory in Groningen, TheNetherlands. From 1993 to 2000 he was a staff member at the ChandraX-ray Centerand Harvard-Smithsonian Center for Astrophysics. From 2000 to 2006, McNamarawas a professor of Physics & Astronomy at Ohio University. Since 2006 he hastaught physics and astronomy at the University of Waterloo, where he remainstoday. McNamara studies galaxies and clusters of galaxies. He is interested in howthey form and evolve under the influence of powerful radio jets launched bysupermassive black holes. His most recent work involves making measurements withthe earth-orbiting Chandra X-ray Observatory and the Atacama Large MillimeterArray, which is the most powerful telescope in existence. He is a former member ofthe Hitomi X-ray Observatory Science Team and is current team member of itssuccessor, the XRISM X-ray observatory, which is planned for launch from Japanin 2022

Steven Allen

Dr. Steve Allen is a Professor of Physics at Stanford University andthe SLAC National Accelerator Laboratory. His research interestsspan the astrophysics of galaxy clusters and their use ascosmological probes, utilizing a broad array of multi-wavelengthobservations. Educated in the UK, he received his PhD in 1995from the University of Cambridge, where he also held a PPARCPostdoctoral Fellowship and a Royal Society University Research

The Chandra X-ray Observatory

xxv

Fellowship. He joined Stanford in 2005 and was co-recipient of the 2008 BrunoRossi Prize of the American Astronomical Society.

Adam Mantz

Dr. Adam Mantz is a Research Scientist in Physics at StanfordUniversity. His research centers on the cosmology and astrophysicsof clusters of galaxies, particularly using X-ray and radioobservations of the intracluster medium, and the development ofrobust statistical techniques for astrophysical applications. Hereceived his PhD from Stanford in 2009, and held a NASAPostdoctoral Fellowship at Goddard Space Flight Center, followed

by a postdoctoral position at the University of Chicago.

The Chandra X-ray Observatory

xxvi