On the Characteristics and Evolution of Dynamically Excited Trans-Neptunian Objects by Cory Shankman B.Sc., University of Western Ontario, 2010 M.Sc., University of British Columbia, 2012 A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY in the Department of Physics and Astronomy c Cory Shankman, 2016 University of Victoria All rights reserved. This dissertation may not be reproduced in whole or in part, by photocopying or other means, without the permission of the author. ii On the Characteristics and Evolution of Dynamically Excited Trans-Neptunian Objects by Cory Shankman B.Sc., University of Western Ontario, 2010 M.Sc., University of British Columbia, 2012 Supervisory Committee Dr. JJ. Kavelaars, Co-Supervisor (NRC Herzberg) Dr. F. Herwig, Co-Supervisor (Department of Physics and Astronomy) Dr. F. Nathoo, Outside Member (Department of Mathematics and Statistics) iii Supervisory Committee Dr. JJ. Kavelaars, Co-Supervisor (NRC Herzberg) Dr. F. Herwig, Co-Supervisor (Department of Physics and Astronomy) Dr. F. Nathoo, Outside Member (Department of Mathematics and Statistics) ABSTRACT The small-body populations of the distant Solar System inform our understanding of the structure, formation, and evolution of the Solar System. The orbits of these Trans-Neptunian Objects (TNOs) act as tracers for dynamical activities either ongo- ing or past. The distributions of TNO sizes are set by, and so probe, the conditions of the formation and evolution of the Solar System. Using data from surveys on the Canada-France-Hawaii Telescope, I constrain the size distribution of a TNO subpopulation: the scattering TNOs. The scattering TNOs are chosen as they have orbits that come in closer to the Sun, therefore allowing smaller TNOs to be detected. The characteristics of size distribution for the small- sized TNOs is an important, and only recently observable, constraint on the formation of this population. I find that the H-distribution is consistent with models where TNOs form as large (50 km - 100 km) aggregates from the proto-planetary nebula. A recent discovery of apparent clustering in the orbits of some TNOs has led to the hypothesis of an additional and unseen planet in the distant Solar System. I examine the formation implications and consequences of such a planet, and the biases in the detected sample used to infer the planet's existence. Via a combination of dynamical simulations, survey simulations, and statistical comparisons of the observed TNOs, I explore the additional planet hypothesis to determine if there exists strong evidence iv for an additional planet in our Solar System. I find that there is currently no strong evidence for the clustering of orbits in the observed sample and that the proposed additional planet does not produce such a signature in models. v Contents Supervisory Committee ii Abstract iii Table of Contents v List of Tables viii List of Figures ix Co-authorship xi Acknowledgements xii 1 Introduction 1 1.1 Detecting TNOs . 3 1.2 Dynamical Classification . 5 1.3 Size and H Distributions . 8 1.4 On the Existence of an Additional Massive Planet in the Distant Solar System . 13 1.5 Methods . 14 1.5.1 Survey Simulator . 14 1.5.2 N-body Integrations . 15 1.6 Thesis Outline . 16 2 OSSOS. II. A Sharp Transition in the Absolute Magnitude Distri- bution of the Kuiper Belt's Scattering Population 17 2.1 Abstract . 17 2.2 Introduction . 18 vi 2.3 Observations . 20 2.4 Methods . 22 2.4.1 Survey Simulator . 24 2.4.2 Models . 25 2.4.3 H-magnitude Distribution . 26 2.4.4 Colors and Light Curves . 29 2.4.5 Statistics . 30 2.5 Results: Absolute Magnitude Distribution . 31 2.6 Discussion . 36 2.6.1 Choice of Model . 36 2.6.2 Arguments for a divot . 38 2.7 Conclusion . 42 3 Full OSSOS sample scattering TNO analysis 44 4 A Ninth Planet Would Produce a Distinctly Different Distant Kuiper Belt 50 4.1 Abstract . 50 4.2 Introduction . 51 4.3 Orbital Integrations . 54 4.4 Simulating Observations with Well-Calibrated Surveys . 57 4.4.1 Superearth-Induced Structure in the Kuiper Belt Region Can't Yet be Observed . 58 4.4.2 A Distant Ninth Planet Requires a Much Larger High-q Popu- lation . 60 4.5 Discussion and Conclusion . 60 5 Consequences of a distant massive planet on the large semi-major axis Trans-Neptunian Objects 64 5.1 Abstract . 64 5.2 Introduction . 65 5.3 Methods . 68 5.4 Results . 72 5.4.1 Signal in Angle Clustering . 72 5.4.2 Orbital Evolution . 74 5.5 Summary and Discussion . 79 vii 5.6 Conclusion . 82 6 OSSOS VI. Striking Biases in the detection of large semimajor axis Trans-Neptunian Objects 84 6.1 Abstract . 84 6.2 Introduction . 85 6.3 Observations and Methods . 87 6.3.1 OSSOS Observed Sample of large-a TNOs . 87 6.3.2 A Note On q Selection Criteria . 87 6.3.3 Survey Simulation of the Observability of Large-a TNOs . 88 6.4 Results . 89 6.4.1 Observing Bias . 89 6.4.2 Angle Clustering in the OSSOS Sample . 92 6.4.3 OSSOS and MPC Sample Comparison . 93 6.5 Discussion and Summary . 95 7 Conclusion 102 7.1 Looking Forward . 104 7.2 Personal Reflections . 105 Bibliography 107 viii List of Tables Table 2.1 List of Detections for Shankman et al. (2016) . 23 Table 2.2 Non-rejectable contrast values for Shankman et al. (2016) . 35 Table 2.3 Population estimates for Shankman et al. (2016) . 35 Table 5.1 List of TNO sample for Shankman et al. (2017) . 70 Table 5.2 List of TNO uncertainties for Shankman et al. (2017) . 71 Table 5.3 List of Examined TNO groups for Shankman et al. (2017) . 71 Table 5.4 List of P9 Test cases for Shankman et al. (2017) . 71 Table 5.5 Fraction of Clones Ejected in Shankman et al. (2017) . 75 Table 6.1 List of OSSOS TNOs with a > 150 au, q > 30 au . 87 ix List of Figures 1.1 Parameters that specify an elliptical orbit . 6 1.2 Minor Planet Center TNOs plotted by orbital classification . 7 1.3 Absolute magnitude distribution schematic . 11 1.4 Main Asteroid Belt H-distribution . 13 2.1 Scattering TNO model. 26 2.2 H-magnitude distribution schematic. 27 2.3 Cumulative orbital parameter distributions for divot and knee H- distributions . 32 2.4 Single slope H-distribution. 33 2.5 Allowable H-distribution models. 34 2.6 Cumulative distribution comparison for the hot and cold inclination models. 37 2.7 Comparison of the acceptable H-distributions for the hot and cold inclination models. 38 2.8 Comparison of the acceptable H-distributions for the different choices for the colour distribution. 39 2.9 Histograms of the population estimates for our preferred (αf , c) H- distribution. 41 3.1 OSSOS Scattering TNO Update: Cumulative distributions . 46 3.2 Allowable H-distribution models for a break at 8.3 . 47 3.3 Allowable H-distribution models for a break at 7.7 . 48 3.4 Allowable H-distribution models for a break at 7.2 . 49 4.1 Simulated TNO orbital elements in Lawler et al. (2016). 55 4.2 Histograms of simulation distributions in Lawler et al. (2016). 56 4.3 Cumulative histograms of simulations in Lawler et al. (2016). 58 x 4.4 Cumulative histograms of the survey simulator biased simulations in Lawler et al. (2016). 63 5.1 All TNOs with q > 30 from the Minor Planet Center database. 67 5.2 Sedna orbital evolution. 73 5.3 2010 GB174 orbital evolution. 74 5.4 Simulation orbital angle confinement. 75 5.5 Simulation movie stills. 76 5.6 Inclination flipping induced by P9. 78 5.7 Sedna i and q evolution. 80 6.1 OSSOS orbital angle detection biases . 91 6.2 OSSOS Ω vs i detection biases . 92 6.3 OSSOS sample orbital angles . 94 6.4 OSSOS and Minor Planet Center samples comparison . 95 6.5 OSSOS survey pointings and detections . 96 6.6 OSSOS sensitivity by choice of model . 100 6.7 OSSOS sensitivity as a function of q . 100 6.8 OSSOS sensitivity to close TNOs . 101 7.1 Pluto's surface as seen by New Horizons . 106 xi CO-AUTHORSHIP This thesis contains collaborative published or submitted works in Chapters 2, 4, 5, and 6. A note at the start of each chapter provides the full author list, state of publication, and reference details for the publication. All works in this thesis were developed with the guidance and insight of my thesis supervisor, JJ Kavelaars. Much of this work is built on analyzing the detections of several surveys. The work of those surveys is noted in each published paper. All detections and survey char- acterisations were provided by the teams leading the surveys. In particular, Michele Bannister, JJ Kavelaars, Brett Gladman, Mike Alexandersen, Katherine Volk, and Jean-Marc Petit were instrumental in designing and carrying out the surveys that provide the detected samples in this Thesis. Chapter 2 was entirely written by me, with contributions to the observing section from JJ Kavelaars. I performed all survey simulations, made all plots, and computed all statistics. This approach is based on previous work of mine, with contributions to the approach made by Brett Gladman at the time. Proofreading and editing was provided by co-authors and in particular by JJ Kavelaars. Chapter 4 was primarily written by Samantha Lawler. I contributed to the writing of the introduction, wrote parts of Section 4.4, and provided general editing and proof- reading.