HOT GASEOUS HALOS AROUND GALAXIES by Michael E. Anderson A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Astronomy and Astrophysics) in The University of Michigan 2013 Doctoral Committee: Professor Joel N. Bregman, Chair Associate Professor Eric F. Bell Professor August Evrard Associate Professor Oleg Y. Gnedin Assistant Professor Christopher J. Miller Associate Professor Jon M. Miller Associate Professor Mateusz Ruszkowski Michael E. Anderson Copyright c 2013 All Rights Reserved To my parents, with love ii ACKNOWLEDGMENTS It is a pleasure to acknowledge the many people and institutions upon whom I have relied during my graduate studies at Michigan. It has been a wonderful experience working with and learning from my advisor, Joel Bregman. I greatly admire his combination of uncannily prescient leaps of big-picture intuition paired with scrupulous attention to details, and to the extent I have learned to think more like a scientist during my PhD program, Joel deserves the credit for this. He has also been unwaveringly supportive of me throughout this process. I really appreciate his willingness to take me on as an unexpected PhD student, his availability, assistance, and forbearance with technical issues large and small, and his insights into the wider culture of academia. The rest of my thesis committee – Eric Bell, Gus Evrard, Oleg Gnedin, Chris Miller, Jon Miller, and Mateusz Ruszkowski – have also helped me in a number of ways. Joel, Eric, and Oleg have been incredibly supportive of Astrocoffee, and I have learned an enormous amount from their lively debates. Jon went out of his way to welcome me to the program and to guide me through the thicket of relevant depart- mental and Rackham requirements. And everyone on my committee has contributed a number of useful suggestions throughout this process, and I really appreciate their attention and their contributions. The department in general has also fostered a very supportive environment. I have benefitted greatly from the large number of opportunities to give talks to the department, and from the genuine interest the faculty take in the personal and aca- demic well-being of the graduate students. The graduate chair, Nuria Calvet, also allowed me to pursue a certificate in Science, Technology, and Public Policy at the Ford School while working on my dissertation. This certificate may not have con- iii tributed directly to my thesis, but I have learned a lot about the connection between science and society, which I hope and expect to serve me well in the rest of my career. Graduate school is also supposed to be a horizontal learning process, and my peers have been a formidable resource during my time here. I would especially like to thank Nate Crockett, Edmund Hodges-Kluck, Ashley King, Matt Miller, Sasha Mu- ratov, and Colin Slater for all their helpful conversations, lessons, and advice, which improved this thesis work immeasurably. I would also gratefully like to acknowledge Xinyu Dai and Jon Miller, who co-authored some of the chapters in this work, as well as Hajira Chaudhry, Elena Gallo, Brendan Miller, and Ezekiel Silverstein, with whom I am collaborating on other work which does not appear in this thesis. Chapters 2, 3, 4, and 5 of this thesis are based on publications in the Astrophysical Journal; the references and copyright information are noted at the beginning of each chapter. Chapter 6 is based on a publication to appear in the Astrophysical Journal (Anderson and Bregman 2013, in preparation). This thesis work has been partially funded by Chandra grant GO9-0089X and by NASA ADAP grant NNX11AJ55G. I am also grateful for an NSF Graduate Research Fellowship and a Rackham One-Term Dissertation Fellowship, which have also generously funded me for parts of my PhD program. Finally, I would like to thank my friends, my girlfriend, and my family, for their love and support throughout this entire process. iv CONTENTS DEDICATION......................................... ii ACKNOWLEDGMENTS .................................... iii LISTOFFIGURES ...................................... ix LISTOFTABLES ....................................... xiii ABSTRACT ........................................... xiv CHAPTER 1 Introduction ......................................... 1 1.1 References ....................................... 8 2 Do Hot Haloes Around Galaxies Contain the Missing Baryons? 11 2.1 Abstract ........................................ 11 2.2 Introduction...................................... 12 2.3 OnMilkyWayParameters............................ 14 2.4 ConstraintsontheMilkyWayHalo ..................... 16 2.4.1 LMC Pulsar Dispersion Measure . 16 2.4.2 OtherConstraints ........................... 18 2.5 OVIIAbsorptioninOtherGalaxies ..................... 20 2.6 X-RaySurfaceBrightness ............................ 24 2.7 Energetics for Gas-Rich Late-Type Galaxies . 26 2.8 TheEffectofFlatterDensityProfiles .................... 30 2.9 Discussion and Conclusion . 33 2.10 Acknowledgements ................................. 36 2.11 References ...................................... 37 v 3 Detection of a Hot Gaseous Halo Around the Giant Spiral Galaxy NGC 1961 ..................................... 49 3.1 Abstract ........................................ 49 3.2 Introduction...................................... 50 3.3 Observation ...................................... 52 3.4 Flat-fielding ...................................... 53 3.4.1 UsingBackgroundFrames ..................... 53 3.4.2 In-field Subtraction, Modeling the Background . 54 3.4.3 In-field Subtraction, Conjugate Technique . 55 3.4.4 PointSources .............................. 56 3.5 RadialSurfaceBrightnessProfile ....................... 59 3.5.1 Parametric Fitting with the β-model .............. 59 3.6 SpectralFitting ................................... 61 3.7 HaloMass ....................................... 63 3.7.1 FlattenedProfiles ........................... 64 3.8 Implications and Conclusion . 65 3.8.1 Generalizing the Conjugate Subtraction Technique . 65 3.8.2 Halo Faintness and the Baryon Budget of NGC 1961. 66 3.8.3 Halo Cooling Rates and Implications for Galaxy Forma- tion ..................................... 68 3.9 Acknowledgements ................................. 71 3.10 References ...................................... 71 4 XMM-Newton Detects a Hot Gaseous Halo in the Fastest Ro- tating Spiral Galaxy UGC 12591 ......................... 79 4.1 Introduction...................................... 79 4.2 ObservationandDataReduction ....................... 80 4.3 SpectralAnalysis .................................. 81 4.4 SpatialAnalysis ................................... 82 4.5 Discussion ....................................... 88 4.5.1 Baryon Mass Components in UGC 12591 . 88 vi 4.5.2 Coolingofthehotgas ........................ 89 4.6 References ....................................... 90 5 Extended Hot Halos Around Isolated Galaxies Observed in the ROSAT All-Sky Survey ................................ 91 5.1 Abstract ........................................ 91 5.2 Introduction...................................... 92 5.3 Sample.......................................... 95 5.4 ConstructingStackedImages ......................... 96 5.5 Analysis.........................................102 5.5.1 Parameterizing the surface brightness profile . 102 5.5.2 ComputingthePSF..........................105 5.6 Simulations ......................................107 5.6.1 Recovering total counts and fit parameters . 111 5.6.2 Recovering countswithin 50kpc . ... ... .... ... ...111 5.6.3 Identifying extended emission . 114 5.6.4 EffectsofchangingthePSF ....................118 5.6.5 Including a combination of point source and extended components................................119 5.6.6 Summaryofsimulations .......................120 5.7 Statistical significance of detections . 121 5.8 Results .........................................125 5.8.1 AverageLuminosity..........................127 5.8.2 AGNemission..............................133 5.8.3 X-raybinaries ..............................134 5.8.4 The LX -LK relation..........................138 5.8.5 HotGasMass ..............................138 5.8.6 Comparisonwithpreviouswork .................145 5.9 Conclusions ......................................146 5.10 Acknowledgements ................................. 148 5.11 References ...................................... 151 vii 6 Modeling X-ray Emission Around Galaxies ................155 6.1 Abstract ........................................155 6.2 Introduction...................................... 156 6.3 Themodel .......................................160 6.3.1 Background................................160 6.3.2 Source ...................................161 6.3.3 Pointsources...............................164 6.4 Simulating images . 165 6.4.1 Simulating Point Sources . 166 6.4.2 DetectingPointSources .......................167 6.5 Example: ChandraDeepFieldSouth ....................168 6.6 The Likelihood Function . 174 6.6.1 Measuring funvig for observation 8595. .179 6.7 Simulated Images with an Extended Source . 179 6.7.1 SourceatLargeOff-AxisAngle..................180 6.7.2 SourceatAimpoint ..........................183 6.8 Application to Real Observation: NGC 720 . 184 6.9 Conclusion.......................................190 6.10 References ...................................... 192 7 Conclusion ...........................................196 7.1 Late-typeGalaxies .................................196