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Development and Preliminary Results of Point Source Observations

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Development and Preliminary Results of Point Source Observations The Atacama Cosmology Telescope: Development and Preliminary Results of Point Source Observations Ryan P. Fisher A DISSERTATION PRESENTED TO THE FACULTY OF PRINCETON UNIVERSITY IN CANDIDACY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY RECOMMENDED FOR ACCEPTANCE BY THE DEPARTMENT OF PHYSICS [Adviser: Joseph W. Fowler] November 2009 c Copyright by Ryan Patrick Fisher, 2009. All rights reserved. Abstract The Atacama Cosmology Telescope (ACT) is a six meter diameter telescope designed to measure the millimeter sky with arcminute angular resolution. The instrument is cur- rently conducting its third season of observations from Cerro Toco in the Chilean Andes. The primary science goal of the experiment is to expand our understanding of cosmology by mapping the temperature fluctuations of the Cosmic Microwave Background (CMB) at angular scales corresponding to multipoles up to ` ∼ 10000: The primary receiver for current ACT observations is the Millimeter Bolometer Ar- ray Camera (MBAC). The instrument is specially designed to observe simultaneously at 148 GHz, 218 GHz and 277 GHz. To accomplish this, the camera has three separate de- tector arrays, each containing approximately 1000 detectors. After discussing the ACT experiment in detail, a discussion of the development and testing of the cold readout elec- tronics for the MBAC is presented. Currently, the ACT collaboration is in the process of generating maps of the microwave sky using our first and second season observations. The analysis used to generate these maps requires careful data calibration to produce maps of the arcminute scale CMB tem- perature fluctuations. Tests and applications of several elements of the ACT calibrations are presented in the context of the second season observations. Scientific exploration has already begun on preliminary maps made using these calibrations. The final portion of this thesis is dedicated to discussing the point sources observed by the ACT. A discus- sion of the techniques used for point source detection and photometry is followed by a presentation of our current measurements of point source spectral indices. iii Acknowledgments I am very grateful for the opportunities I have had to learn and grow as a researcher thanks to Princeton University. The atmosphere of excitement for discovery in the Physics Department is like nothing I have ever experienced before. Through my years of gradu- ate work, I have been guided and supported by Lyman Page, Suzanne Staggs, and my advisor, Joseph Fowler. I truly appreciate having the opportunity to study under such a brilliant trio of scientists. I especially would like to thank Joe for helping me through my years of graduate work and for spending countless hours having discussions with me on topics ranging from cosmology to coffee. I owe very much of this thesis to the work of so many other individuals. I have been lucky to both follow in the footsteps of many great scientists who have come before me, and walk the path with the most excellent of peers one could wish for. In particular, I have had the pleasure of working with and learning from the many members who have been a part of the ACT collaboration including: Mike Niemack, Judy Lau, Toby Marriage, Asad Aboobaker, Yue Zhao, Tom Essinger-Hileman, John Appel, Lucas Parker, Sudeep Das, Amir Hajian, Viviana Acquaviva, Beth Reid, Kevin Huffenburger, Elia Battistelli, Rolondo Du¨nner, Matt Hasselfield, Mike Nolta, Jon Sievers, Neelima Sehgal, Matt Hilton, Jo Dunk- ley, Norm Jarosik, Kavi Moodley, David Spergel, Omelan Stryzak, Daniel Swetz, Danica Marsden, Krista Martocci, Alex Dahlen, Leizhi Sun, Sarah Denny, Mark Halpern, Jeff Klein, Michele Limon, Robert Lupton, Randy Doriese, Gene Hilton, Jay Chervenak, Ryan Warne and Audrey Sederberg, to name but a few. I would like to thank all of the staff of the Physics Department, and especially those who are always so friendly and helpful to me: Barbara Grunwerg, Claude Champagne, Mary Santay, Laurel Lerner, Angela Glenn, John Washington and Mike Peloso. I would also like to particularly thank the members of the machine shop lunch crew, Glenn, Bill, Ray, and occasionally Bob Austin, who have shared many an excellent conversation with me. I would like to especially thank the two individuals who have shared far more than just an office with me over the last few years, Eric Switzer and Adam Hincks, for their camaraderie, help and friendship. My years at Princeton have gifted me with so many friends, including many whom I have already acknowledged as peers. I could hardly imagine listing the countless number of individuals who have brought an ounce of happiness to my time at Princeton, but I would like to point out a few individuals who have been truly good friends. First, I would like to thank the basement crew of Justin Brown, Rajat Ghosh, Scott Seltzer, Hoan Dang, and Giorgos Vasilakis, for providing me with both friendship and entertainment on the many occasions when I required it. Next I would like to thank Omelan Stryzak and Ted Lewis for always providing me with the help I needed, but more importantly by far for their friendships extending beyond the walls and topics of Jadwin Hall. Finally, I would like to thank Sam Taylor, Lewis Andrew Wray, Nick Pavlov and Jeremy Booher for all of the fun times we’ve spent together. To Nick and Justin and Jeremy, thanks for all of the laughter you have brought into my life all these years. To all of my friends: I will miss you dearly iv when I move on, and I hope that our paths will cross again. I owe so very much to the love and support of my parents, Jackie and Gary Fisher. Thank you both for helping me through everything that I have done. Throughout my years of study, I have always had the love of my life by my side. She has always helped me through my greatest times of need and given me a reason to be happy every day. My greatest thanks go to you, Julie, I love you, and I dedicate this thesis to you and our future together. v vi Contents Abstract......................................... iii Acknowledgments................................... iv List of Figures.....................................x List of Tables...................................... xiii 1 Cosmology, the CMB, and the Atacama Cosmology Telescope1 1.1 The CMB.....................................3 1.2 Primary Anisotropies of the CMB........................5 1.3 Secondary Effects................................ 11 1.4 Millimeter Astronomy............................... 13 1.5 The ACT Experiment............................... 14 1.5.1 ACT Observations............................ 16 1.6 Outline of Thesis................................. 17 2 The ACT Telescope Systems Overview 19 2.1 Telescope Infrastructure............................. 20 2.1.1 Measurements of the Telescope Beam................. 24 2.2 The MBAC.................................... 26 2.2.1 ACT Cold Optics and Bandpasses................... 26 2.2.2 Detector Arrays.............................. 26 2.2.3 Detector Circuitry............................. 31 2.2.4 Cold Readout Electronics........................ 35 2.3 Receiver Cabin Electronics........................... 40 2.3.1 The MCE Readout System....................... 41 2.3.2 Data Modes in the MCE......................... 41 2.4 Data Readout Computers............................ 45 2.5 Data........................................ 46 3 Tests of Multiplexing Electronics for the Atacama Cosmology Telescope 49 3.1 Mux Chip Testing Experimental Setup..................... 50 3.2 IcMax Characterization.............................. 54 3.2.1 Selection Criteria............................. 54 3.2.2 Analysis of Desired Biasing Currents.................. 56 3.2.3 Wafer Characterization......................... 61 3.2.4 Anticipated Requirements for Mux Chips................ 63 vii 3.3 Advancements in Mux Chip Production and Screening After the Initial Study 65 3.4 Automated Testing of Mux Chip Assemblies.................. 65 3.5 Aggregate Testing Results............................ 67 3.6 Final Array Chip Performance.......................... 69 4 ACT Calibration for 2008 71 4.1 Detector and Readout Circuit Formalism.................... 72 4.2 The Load Curve Test............................... 79 4.2.1 2008 AR1 IV Curve Problem and Solution............... 83 4.3 The Bias Step Test................................ 85 4.3.1 Analysis of Bias Step Test Files..................... 88 4.3.2 Tests of the Analysis Code....................... 91 4.3.3 Comparisons of IV Curve and Bias Step Tests............ 103 4.4 Atmospheric Flat Fielding Calibration...................... 109 4.4.1 Concept.................................. 109 4.4.2 Implementation.............................. 112 4.4.3 Detailed Description of AR3 Difficulties................ 117 4.5 Efficiency Computations............................. 118 4.6 Final Calibration Method and Results...................... 122 4.6.1 Absolute Calibration to Uranus..................... 131 4.6.2 Conclusion................................ 132 5 Point Sources in the ACT Survey 133 5.1 Point Source Types................................ 134 5.1.1 Radio Source Radiation Mechanism.................. 134 5.1.2 IR Source Radiation........................... 137 5.2 Project Motivation and Goals.......................... 139 5.2.1 Spectral Indices............................. 139 5.2.2 Source Characteristics.......................... 140 5.2.3 Cluster Observations.......................... 140 5.2.4 Additional Motivations.......................... 141 5.2.5 Goals of This Research........................
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