Overcoming the Challenges of 21Cm Cosmology
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Aaron R. Parsons Campbell Hall 601, Dept
1/4 Curriculum Vitae Aaron R. Parsons Campbell Hall 601, Dept. of Astronomy (510) 406-4322 University of California, Berkeley [email protected] Berkeley, CA 94720 USA http://bit.ly/aaronparsons Education University of California, Berkeley Ph.D., Astrophysics. Advisor: Donald C. Backer Dec. 2009 M.A., Astrophysics Sept. 2006 Harvard University, Double B.A., Physics and Mathematics, cum laude June, 2002 Professional Positions Assistant Professor 2011- Dept. of Astronomy, U. California, Berkeley NSF Astronomy and Astrophysics Postdoctoral Fellow 2009-2011 Dept. of Astronomy, U. California, Berkeley Charles H. Townes Postdoctoral Honorary Fellow 2009-2011 Space Sciences Laboratory, U. California, Berkeley NAIC Pre-Doctoral Researcher 2007-2009 Arecibo Observatory, Puerto Rico. Local Supervisor: C. Salter Graduate Student Researcher 2004-2009 Dept. of Astronomy, U. California, Berkeley. Advisor: D. Backer Junior Development Engineer 2002-2004 Space Sciences Laboratory, U. California, Berkeley. Supervisor: D. Werthimer Honors and Awards Mary Elizabeth Uhl Prize for Outstanding Scholarly Achievement 2009 International Union of Radio Science (URSI) Young Scientist Award 2005 UC Berkeley Space Sciences Summer Fellowship 2005 Harvard College Scholarship for Academic Excellence 2002 Harvard University: four times Deans List 1998-2002 Robert C. Byrd Honors Scholarship 1998 Julius Poole Scholarship 1998 Elk’s Scholarship 1998 Professional Activities Center for Astronomy Signal Processing and Electronics Research (CASPER) advisory board member, -
Simulating Electron Transport and Synchrotron Emission in Radio Galaxies: Shock Acceleration and Synchrotron Aging in Three-Dimensional Flows
CORE Metadata, citation and similar papers at core.ac.uk Provided by CERN Document Server Simulating Electron Transport and Synchrotron Emission in Radio Galaxies: Shock Acceleration and Synchrotron Aging in Three-Dimensional Flows I. L. Tregillis 1,T.W.Jones1, Dongsu Ryu 2 ABSTRACT We present the first three-dimensional MHD radio galaxy simulations that explicitly model transport of relativistic electrons, including diffusive acceleration at shocks as well as radiative and adiabatic cooling in smooth flows. We discuss here three simulations of light Mach 8 jets, designed to explore the effects of shock acceleration and radiative aging on the nonthermal particle populations that give rise to synchrotron and inverse-Compton radiations. Because our goal is to explore the connection between the large-scale flow dynamics and the small-scale physics underlying the observed emissions from real radio galaxies, we combine the magnetic field and relativistic electron momentum distribution information to compute an approximate but self-consistent synchrotron emissivity and produce detailed synthetic radio telescope observations. We have gained several key insights from this approach: 1. The jet head in these multidimensional simulations is an extremely complex environment. The classical jet termination shock is often absent, but motions of the jet terminus spin a “shock-web complex” within the backflowing jet material of the head. 2. Correct interpretation of the spectral distribution of energetic electrons in these simulations relies partly upon understanding the shock-web complex, for it can give rise to distributions that confound interpretation in terms of the standard model for radiative aging of radio galaxies. 3. The magnetic field outside of the jet itself becomes very intermittent and filamentary in these simulations, yet adiabatic expansion causes most of the cocoon volume to be occupied by field strengths considerably diminished below the nominal jet value. -
The Jets in Radio Galaxies
The jets in radio galaxies Martin John Hardcastle Churchill College September 1996 A dissertation submitted in candidature for the degree of Doctor of Philosophy in the University of Cambridge i `Glaucon: ª...But how did you mean the study of astronomy to be reformed, so as to serve our pur- poses?º Socrates: ªIn this way. These intricate traceries on the sky are, no doubt, the loveliest and most perfect of material things, but still part of the visibleworld, and therefore they fall far short of the true realities Ð the real relativevelocities,in theworld of purenumber and all geometrical ®gures, of the movements which carry round the bodies involved in them. These, you will agree, can be conceived by reason and thought, not by the eye.º Glaucon: ªExactly.º Socrates: ªAccordingly, we must use the embroidered heaven as a model to illustrateour study of these realities, just as one might use diagrams exquisitely drawn by some consummate artist like Daedalus. An expert in geometry, meeting with such designs, would admire their ®nished workmanship, but he wouldthink it absurd to studythem in all earnest with the expectation of ®nding in their proportionsthe exact ratio of any one number to another...º ' Ð Plato (429±347 BC), The Republic, trans. F.M. Cornford. ii Contents 1 Introduction 1 1.1 Thisthesis...................................... ... 1 1.2 Abriefhistory................................... .... 2 1.3 Synchrotronphysics........ ........... ........... ...... 4 1.4 Currentobservationalknowledgeintheradio . ............. 5 1.4.1 Jets ........................................ 6 1.4.2 Coresornuclei ................................. 6 1.4.3 Hotspots ..................................... 7 1.4.4 Largescalestructure . .... 7 1.4.5 Theradiosourcemenagerie . .... 8 1.4.6 Observationaltrends . -
Astro2020 Science White Paper Cosmology with the Highly Redshifted 21 Cm Line
Astro2020 Science White Paper Cosmology with the Highly Redshifted 21 cm Line Thematic Areas: Planetary Systems Star and Planet Formation Formation and Evolution of Compact Objects 3Cosmology and Fundamental Physics Stars and Stellar Evolution Resolved Stellar Populations and their Environments Galaxy Evolution Multi-Messenger Astronomy and Astrophysics Principal Author: Name: Adrian Liu Institution: McGill University Email: [email protected] Phone: (514) 716-0194 Co-authors: (names and institutions) James Aguirre (University of Pennsylvania), Joshua S. Dillon (UC Berkeley), Steven R. Furlanetto (UCLA), Chris Carilli (National Radio Astronomy Observatory), Yacine Ali-Haimoud (New York University), Marcelo Alvarez (University of California, Berkeley), Adam Beardsley (Arizona State University), George Becker (University of California, Riverside), Judd Bowman (Arizona State University), Patrick Breysse (Canadian Institute for Theoretical Astrophysics), Volker Bromm (University of Texas at Austin), Philip Bull (Queen Mary University of London), Jack Burns (University of Colorado Boulder), Isabella P. Carucci (University College London), Tzu-Ching Chang (Jet Propulsion Laboratory), Hsin Chiang (McGill University), Joanne Cohn (University of California, Berkeley), David DeBoer (University of California, Berkeley), Cora Dvorkin (Harvard University), Anastasia Fialkov (Sussex University), Nick Gnedin (Fermilab), Bryna Hazelton (University of Washington), Daniel Jacobs (Arizona State University), Marc Klein Wolt (Radboud University -
Cosmology with the Highly Redshifted 21 Cm Line
Astro2020 Science White Paper Cosmology with the Highly Redshifted 21 cm Line Thematic Areas: Planetary Systems Star and Planet Formation Formation and Evolution of Compact Objects 3Cosmology and Fundamental Physics Stars and Stellar Evolution Resolved Stellar Populations and their Environments Galaxy Evolution Multi-Messenger Astronomy and Astrophysics Principal Author: Name: Adrian Liu Institution: McGill University Email: [email protected] Phone: (514) 716-0194 Co-authors: (names and institutions) James Aguirre (University of Pennsylvania), Joshua S. Dillon (UC Berkeley), Steven R. Furlanetto (UCLA), Chris Carilli (National Radio Astronomy Observatory), Yacine Ali-Haimoud (New York University), Marcelo Alvarez (University of California, Berkeley), Adam Beardsley (Arizona State University), George Becker (University of California, Riverside), Judd Bowman (Arizona State University), Patrick Breysse (Canadian Institute for Theoretical Astrophysics), Volker Bromm (University of Texas at Austin), Philip Bull (Queen Mary University of London), Jack Burns (University of Colorado Boulder), Isabella P. Carucci (University College London), Tzu-Ching Chang (Jet Propulsion Laboratory), Hsin Chiang (McGill University), Joanne Cohn (University of California, Berkeley), David DeBoer (University of California, Berkeley), Cora Dvorkin (Harvard University), Anastasia Fialkov (Sussex University), Nick Gnedin (Fermilab), Bryna Hazelton (University of Washington), Daniel Jacobs (Arizona State University), Marc Klein Wolt (Radboud University -
Empirical Covariance Modeling for 21 Cm Power Spectrum Estimation: a Method Demonstration and New Limits from Early Murchison Widefield Array 128-Tile Data
Empirical covariance modeling for 21 cm power spectrum estimation: A method demonstration and new limits from early Murchison Widefield Array 128-tile data The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Dillon, Joshua S., et al. "Empirical covariance modeling for 21 cm power spectrum estimation: A method demonstration and new limits from early Murchison Widefield Array 128-tile data." Phys. Rev. D 91, 123011 (June 2015). © 2015 American Physical Society As Published http://dx.doi.org/10.1103/PhysRevD.91.123011 Publisher American Physical Society Version Final published version Citable link http://hdl.handle.net/1721.1/97502 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. PHYSICAL REVIEW D 91, 123011 (2015) Empirical covariance modeling for 21 cm power spectrum estimation: A method demonstration and new limits from early Murchison Widefield Array 128-tile data Joshua S. Dillon,1,2,* Abraham R. Neben,1,2 Jacqueline N. Hewitt,1,2 Max Tegmark,1,2 N. Barry,3 A. P. Beardsley,3 J. D. Bowman,4 F. Briggs,5,6 P. Carroll,3 A. de Oliveira-Costa,1,2 A. Ewall-Wice,1,2 L. Feng,1,2 L. J. Greenhill,7 B. J. Hazelton,3 L. Hernquist,7 N. Hurley-Walker,8 D. C. Jacobs,4 H. S. Kim,9,6 P. Kittiwisit,4 E. Lenc,10,6 J. Line,9,6 A. -
Instrumentation for Radio Interferometers with Antennas on a Regular Grid by Deepthi Bhavana Gorthi a Dissertation Submitted In
Instrumentation for Radio Interferometers with Antennas on a Regular Grid by Deepthi Bhavana Gorthi A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Astrophysics in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Aaron Parsons, Chair Professor Jessica Lu Professor Uros Seljak Spring 2021 Instrumentation for Radio Interferometers with Antennas on a Regular Grid Copyright 2021 by Deepthi Bhavana Gorthi 1 Abstract Instrumentation for Radio Interferometers with Antennas on a Regular Grid by Deepthi Bhavana Gorthi Doctor of Philosophy in Astrophysics University of California, Berkeley Professor Aaron Parsons, Chair In the past two decades, a rebirth of interest in low-frequency radio astronomy, for 21 cm tomography of the Epoch of Reionization, has given rise to a new class of radio interferom- eters with N 100 antennas. The availability of low-noise receivers that do not require cryogenic cooling has driven down the cost of antennas, making it affordable to build sensi- tivity with numerous small antennas rather than traditional large dish structures. However, the computational- and storage-costs of such radio arrays, determined by the (N 2) scaling of visibility products that need to be computed for calibration and imaging, becomeO propor- tional to the cost of the array itself and drive up the overall cost of the radio telescope. When antennas in the array are built on a regular grid, direct-imaging methods based on spatial Fourier transforms of the array can be exploited to avoid computing the intermediate visibility matrices that drive the unfavorable scaling. -
Instrumentation for Wide Bandwidth Radio Astronomy
Instrumentation for Wide Bandwidth Radio Astronomy Thesis by Glenn Evans Jones In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy California Institute of Technology Pasadena, California 2010 (Defended September 25, 2009) ii c 2010 Glenn Evans Jones All Rights Reserved iii To my family. iv Acknowledgements Since I was very young I have been fascinated by radio telescopes, but despite a keen interest in other areas of electronics, I never learned how they were used until I began working with my research advisor, Sandy Weinreb. As a fellow electronics and technology enthusiast, I cannot imagine a better person to introduce me to the field of radio astronomy which has steadily become my career. From the very beginning, he has been a tireless advocate for me while sharing his broad experience across the gamut of radio astronomy instrumentation and observations. One of the most important ways in which Sandy has influenced me professionally is by pursuing every available opportunity to introduce me to members of the radio astronomy community. I also very much appreciate the support provided by my academic advisor, Dave Rutledge. Dave provided a wide range of useful suggestions and encouragement during group meetings, and looked out for me from the very beginning. Each of the other members of my thesis committee also deserves special thanks apart from my gratitude to them for serving on the committee. P.P. Vaidyanathan introduced me to digital signal processing and his clear, insightful lectures helped to inspire my interest in the field. Tony Read- head's courses on radio astronomy instrumentation and radiative processes significantly improved my understanding of the details of radio astronomy. -
UC Berkeley UC Berkeley Electronic Theses and Dissertations
UC Berkeley UC Berkeley Electronic Theses and Dissertations Title Instrumentation for Radio Interferometers with Antennas on a Regular Grid Permalink https://escholarship.org/uc/item/5tj476tn Author Gorthi, Deepthi Bhavana Publication Date 2021 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California Instrumentation for Radio Interferometers with Antennas on a Regular Grid by Deepthi Bhavana Gorthi A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Astrophysics in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Aaron Parsons, Chair Professor Jessica Lu Professor Uros Seljak Spring 2021 Instrumentation for Radio Interferometers with Antennas on a Regular Grid Copyright 2021 by Deepthi Bhavana Gorthi 1 Abstract Instrumentation for Radio Interferometers with Antennas on a Regular Grid by Deepthi Bhavana Gorthi Doctor of Philosophy in Astrophysics University of California, Berkeley Professor Aaron Parsons, Chair In the past two decades, a rebirth of interest in low-frequency radio astronomy, for 21 cm tomography of the Epoch of Reionization, has given rise to a new class of radio interferom- eters with N 100 antennas. The availability of low-noise receivers that do not require cryogenic cooling has driven down the cost of antennas, making it affordable to build sensi- tivity with numerous small antennas rather than traditional large dish structures. However, the computational- and storage-costs of such radio arrays, determined by the (N 2) scaling of visibility products that need to be computed for calibration and imaging, becomeO propor- tional to the cost of the array itself and drive up the overall cost of the radio telescope. -
Observing the Epoch of Reionization: Power Spectrum Limits and Commissioning Next Generation 21Cm Experiments
Observing the Epoch of Reionization: Power Spectrum Limits and Commissioning Next Generation 21 cm Experiments By Zaki Shiraz Ali A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Astrophysics in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Aaron Parsons, Chair Professor Carl Heiles Professor Adrian Lee Professor Chung-Pei Ma Summer 2018 Observing the Epoch of Reionization: Power Spectrum Limits and Commissioning Next Generation 21 cm Experiments Copyright 2018 by Zaki Shiraz Ali 1 Abstract Observing the Epoch of Reionization: Power Spectrum Limits and Commissioning Next Generation 21 cm Experiments by Zaki Shiraz Ali Doctor of Philosophy in Astrophysics University of California, Berkeley Professor Aaron Parsons, Chair As one of the last unobserved frontiers in the Universe, the Epoch of Reionization (EoR) marks the period when the Universe transitioned from a neutral state to an ionized state, marking the last global phase change. Understanding how the EoR evolved over time and when it occurred will provide evidence for the nature of the first luminous sources of the Universe. Specifically, we’ll be able to answer questions such as what were the first galaxies like in terms of their luminosities, masses, and spectral energy distributions? Were they similar to todays galaxies? How did they form? How were they spatially distributed? These questions and many others begin to probe the early times of galaxy formation, a field in need of observations of the earliest galaxies. In the first chapter, I provide an introduction to 21 cm cosmology, which uses the 21 cm line transition from neutral hydrogen to study the evolution of the Universe. -
Meeting Abstracts
228th AAS San Diego, CA – June, 2016 Meeting Abstracts Session Table of Contents 100 – Welcome Address by AAS President Photoionized Plasmas, Tim Kallman (NASA 301 – The Polarization of the Cosmic Meg Urry GSFC) Microwave Background: Current Status and 101 – Kavli Foundation Lecture: Observation 201 – Extrasolar Planets: Atmospheres Future Prospects of Gravitational Waves, Gabriela Gonzalez 202 – Evolution of Galaxies 302 – Bridging Laboratory & Astrophysics: (LIGO) 203 – Bridging Laboratory & Astrophysics: Atomic Physics in X-rays 102 – The NASA K2 Mission Molecules in the mm II 303 – The Limits of Scientific Cosmology: 103 – Galaxies Big and Small 204 – The Limits of Scientific Cosmology: Town Hall 104 – Bridging Laboratory & Astrophysics: Setting the Stage 304 – Star Formation in a Range of Dust & Ices in the mm and X-rays 205 – Small Telescope Research Environments 105 – College Astronomy Education: Communities of Practice: Research Areas 305 – Plenary Talk: From the First Stars and Research, Resources, and Getting Involved Suitable for Small Telescopes Galaxies to the Epoch of Reionization: 20 106 – Small Telescope Research 206 – Plenary Talk: APOGEE: The New View Years of Computational Progress, Michael Communities of Practice: Pro-Am of the Milky Way -- Large Scale Galactic Norman (UC San Diego) Communities of Practice Structure, Jo Bovy (University of Toronto) 308 – Star Formation, Associations, and 107 – Plenary Talk: From Space Archeology 208 – Classification and Properties of Young Stellar Objects in the Milky Way to Serving -
Measuring the Gravitational Wave Background Using Precision Pulsar Timing by Paul B. Demorest BA
Measuring the Gravitational Wave Background using Precision Pulsar Timing by Paul B. Demorest B.A. (University of California, Berkeley) 2000 M.A. (University of California, Berkeley) 2002 A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Physics in the GRADUATE DIVISION of the UNIVERSITY OF CALIFORNIA, BERKELEY Committee in charge: Professor Donald Backer, Co-chair Professor Steven Boggs, Co-chair Professor William Holzapfel Professor Carl Heiles Spring 2007 The dissertation of Paul B. Demorest is approved: Co-chair Date Co-chair Date Date Date University of California, Berkeley Spring 2007 Measuring the Gravitational Wave Background using Precision Pulsar Timing Copyright 2007 by Paul B. Demorest 1 Abstract Measuring the Gravitational Wave Background using Precision Pulsar Timing by Paul B. Demorest Doctor of Philosophy in Physics University of California, Berkeley Professor Donald Backer, Co-chair Professor Steven Boggs, Co-chair We investigate the possibility of using high precision timing measurements of radio pulsars to constrain or detect the stochastic gravitational wave background (GWB). Improved algorithms are presented for more accurately determining the pulse times of arrival at Earth and characterizing pulse profile shape variation. Next, we describe the design and construction of a new set of pulsar backends based on clusters of standard personal computers. These machines, the Astronomy Signal Processors (ASPs), coherently correct the pulse broadening caused by interstellar plasma dispersion. Since they are based in software, they are inherently more flexible than previous generations of pulsar data recorders. In addition, they provide increased bandwidth and quantization accuracy. We apply these methods to 2.5 years worth 2 of millisecond pulsar data recorded with the ASP systems at the Arecibo and Green Bank Telescopes, and present pulse profiles, dispersion measure variation, and timing model parameters derived from this data.