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An Analysis of the Peculiar Velocity Structure in Galaxy Cluster A154

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An Analysis of the Peculiar Velocity Structure in Galaxy Cluster A154 AN ANALYSIS OF THE PECULIAR VELOCITY STRUCTURE IN GALAXY CLUSTER A154 A DISSERTATION SUBMITTED TO THE GRADUATE SCHOOL IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE DOCTOR OF EDUCATION BY RYAN WESLEY TOBIN DR. ROBERT BERRINGTON - ADVISOR BALL STATE UNIVERSITY MUNCIE, INDIANA DECEMBER 2016 To Elijah, Samuel and Zachary... The important thing is not to stop questioning. Curiosity has its own reason for existing. {Albert Einstein Never fear answers, only fear running out of questions. {Unknown Acknowledgements I would like to thank Dr. Robert Berrington for his years of patience, advice and encouragement. I would also like to thank my graduate committee members, Dr. Patricia Lang, Dr. Ronald Kaitchuk and Dr. Thalia Mulvihill, and the Department of Physics and Astronomy faculty for their support, instruction and advice throughout the years. I also want to thank my wife, Amy, and my sons, Elijah and Samuel, who supported me when I was gone | but always made me glad to come home. This research is a testament to their support and perseverance as much as it is to mine own. Finally, I would like to thank Mr. Marc Semanchik, who helped me to overcome a disability and provided me with a sounding board to discuss and refine my understanding of various complex topics. Without your help, I would never have been able to finish. Thank you all! Contents 1 Introduction 1 1.1 Understanding Galaxy Clusters . 2 1.2 Importance of Further Study . 2 1.3 Abell 154 and Dissertation Overview . 3 2 Background 5 2.1 Hierarchical Merging . 5 2.2 Cluster Properties . 6 2.2.1 Cosmic Distances . 7 2.2.2 Cluster Mass . 13 2.2.3 Timescales . 15 2.3 The Relaxed Cluster . 19 2.3.1 Distributions . 20 2.3.2 Cooling Flows and X-ray Emission . 23 2.4 The Merging Cluster . 26 2.4.1 Merger Shocks . 27 2.4.2 Cluster Environments . 28 2.5 Prior Studies of Abell 154 . 30 2.5.1 Morphology and Appearance . 33 2.5.2 Cluster Core . 34 iii 2.5.3 Previous Radial Velocities . 37 2.5.4 X-ray Sources and Cooling Flow Signatures . 37 2.5.5 Photometric Analysis . 41 3 Radial Velocity Measurements 42 3.1 New Data . 42 3.1.1 Targets for Observation . 43 3.1.2 Observations . 43 3.1.3 Reduction . 44 3.1.4 Reconciling Absorption- and Emission-Based Data . 55 3.2 Literature Data . 55 3.3 Compilation of Data . 57 3.3.1 Reconciling Literature Data with New Data . 57 4 Data Analysis And Discussion 62 4.1 Statistical Analysis . 62 4.1.1 3-σ Clipping . 64 4.1.2 Gaussian Fitting . 68 4.1.3 Analysis in Two and Three Dimensions . 75 4.1.4 Statistical Rejections . 76 4.2 Gaussian Fitting and Subgroup Analysis . 83 4.2.1 Group A Analysis . 87 4.2.2 Group B Analysis . 87 4.2.3 Additional Gaussian Components . 89 4.2.4 Subgrouping . 94 4.2.5 Core Structure . 94 4.2.6 Summary of Statistical Results . 97 4.3 Radio Data . 97 iv 4.4 X-ray Data . 100 4.5 Gravitational Binding . 101 4.5.1 Projected Mass Versus Virial Mass . 103 4.5.2 Two-Body Analysis . 104 5 Summary And Conclusions 108 5.1 Summary . 108 5.1.1 Group A . 109 5.1.2 Group B . 109 5.2 Drawing Conclusions . 111 5.3 Future Work . 113 5.3.1 Current Limitations . 113 5.3.2 X-ray Emission and the Sunyaev-Zel'dovich Effect . 114 5.3.3 Metallicity and Stellar Population Analyses . 115 5.3.4 Computational/Numerical Modeling . 115 Appendix 116 A.1 Literature Summary . 117 A.2 New Measurements . 120 A.3 Final Catalog . 128 A.4 Stellar Data . 139 Bibliography 146 v List of Figures 2.1 Spectrum of a galaxy in Abell 154. 9 2.2 Overlayed spectra of a galaxy from Abell 154 and the Andromeda galaxy. 10 2.3 Temperature as a function of radius in cooling flow clusters. 24 2.4 Temperature as a function of radius in non-cooling flow clusters. 25 2.5 X-ray intensity as a function of position. 26 2.6 Abell 154 from the POSS-II survey (inverted). 31 2.7 Abell 154 core from the POSS-II survey (inverted). 32 2.8 Einstein X-ray image of Abell 154. 39 2.9 X-ray contour image of the core of Abell 154. 40 3.1 Targets for radial velocity measurements. 45 3.2 FXCOR interactive display. 48 3.3 FXCOR graphical output of a galaxy in Abell 154. 49 3.4 FXCOR graphical output of a star. 50 3.5 Stellar targets. 53 3.6 Galactic radial velocities in Abell 154. 59 3.7 Abell 154 2D histogram. 60 3.8 Abell 154 velocity histogram. 61 4.1 Abell 154 histogram. 63 4.2 Initial 3-σ histogram. 65 vi 4.3 Abell 154 by group. 69 4.4 Histogram of the positions of all 205 galaxies with radial velocity measurements. 70 4.5 Histogram of the positions of galaxies. 70 4.6 Histogram of the positions of Group A galaxies. 70 4.7 Histogram of the positions of Group B galaxies. 70 4.8 Right ascension and declination as a function of radial velocity. 71 4.9 Abell 154 radial velocity histogram by group. 81 4.10 Group A and Group B histograms. 82 4.11 3-σ clipped Dressler-Shectman bubble plot. 84 4.12 Dressler-Shectman bubble plot of Group B galaxies. 85 4.13 Dressler-Shectman bubble plot of Group A galaxies. 86 4.14 Group A histogram. 88 4.15 Group B histogram. 90 4.16 Group B histogram. 91 4.17 Group B double root residual plot. 93 4.18 Group B histogram with subgroups. 96 4.19 Group A map overlay. 98 4.20 Group B map overlay. 99 4.21 Subgroup B1 and Subgroup B2 map. 100 4.22 X-ray emission in Abell 154. 102 4.23 Group A to Group B gravitational binding. 106 4.24 Subgroup B1 to Subgroup B2 gravitational binding. 107 vii List of Tables 2.1 Typical custer properties. 19 2.2 Typical timescales. 19 2.3 Abell 154 information. 34 3.1 Targets for observation. 44 3.2 Observations at Kitt-Peak National Observatory. 46 3.3 Emission reference spectra. 54 3.4 Literature radial velocity sources. 56 3.5 Literature self-consistency. 58 4.1 KMM and GMM two group analysis..
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