NRAO Enews Volume 12, Issue 5 • 13 June 2019
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The Global Jet Structure of the Archetypical Quasar 3C 273
galaxies Article The Global Jet Structure of the Archetypical Quasar 3C 273 Kazunori Akiyama 1,2,3,*, Keiichi Asada 4, Vincent L. Fish 2 ID , Masanori Nakamura 4, Kazuhiro Hada 3 ID , Hiroshi Nagai 3 and Colin J. Lonsdale 2 1 National Radio Astronomy Observatory, 520 Edgemont Rd, Charlottesville, VA 22903, USA 2 Massachusetts Institute of Technology, Haystack Observatory, 99 Millstone Rd, Westford, MA 01886, USA; vfi[email protected] (V.L.F.); [email protected] (C.J.L.) 3 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; [email protected] (K.H.); [email protected] (H.N.) 4 Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan; [email protected] (K.A.); [email protected] (M.N.) * Correspondence: [email protected] Received: 16 September 2017; Accepted: 8 January 2018; Published: 24 January 2018 Abstract: A key question in the formation of the relativistic jets in active galactic nuclei (AGNs) is the collimation process of their energetic plasma flow launched from the central supermassive black hole (SMBH). Recent observations of nearby low-luminosity radio galaxies exhibit a clear picture of parabolic collimation inside the Bondi accretion radius. On the other hand, little is known of the observational properties of jet collimation in more luminous quasars, where the accretion flow may be significantly different due to much higher accretion rates. In this paper, we present preliminary results of multi-frequency observations of the archetypal quasar 3C 273 with the Very Long Baseline Array (VLBA) at 1.4, 15, and 43 GHz, and Multi-Element Radio Linked Interferometer Network (MERLIN) at 1.6 GHz. -
Astro2020 APC White Paper Panel on Radio
Astro2020 APC White Paper Panel on Radio, Millimeter, and Submillimeter Observations from the Ground The Case for a Fully Funded Green Bank Telescope Brief Description [350 character limit]: The NSF has reduced its funding for peer-reviewed use on the GBT to ~3900 hours/year, 60% of available science time. This greatly increases the telescope pressure & fragments the schedule, making it very difficult to allocate time for even the highest rated projects planned for the next decade. Here we seek funding for 1500 more hours annually. Principal Author: K. O’Neil (Green Bank Observatory; [email protected]) Co-authors: Felix J Lockman (Green Bank Observatory), Filippo D'Ammando (INAF-IRA Bologna), Will Armentrout (Green Bank Observatory), Shami Chatterjee (Cornell University), Jim Cordes (Cornell University), Martin Cordiner (NASA GSFC), David Frayer (Green Bank Observatory), Luke Zoltan Kelley (Northwestern University), Natalia Lewandowska (West Virginia University), Duncan Lorimer (WVU), Brian Mason (NRAO), Maura McLaughlin (West Virginia University), Tony Mroczkowski (European Southern Observatory), Hooshang Nayyeri (UC Irvine), Eric Perlman (Florida Institute of Technology), Bindu Rani (NASA Goddard Space Flight Center), Dominik Riechers (Cornell University), Martin Sahlan (Uppsala University), Ian Stephens (CfA/SAO), Patrick Taylor (Lunar and Planetary Institute), Francisco Villaescusa- Navarro (Center for Computational Astrophysics, Flatiron Institute) Endosers: Esteban D. Araya (Western Illinois University), Hector Arce (Yale -
EDGES Memo #054
EDGES MEMO #054 MASSACHUSETTS INSTITUTE OF TECHNOLOGY HAYSTACK OBSERVATORY WESTFORD, MASSACHUSETTS 01886 December 1, 2009 Telephone: 781-981-5407 Fax: 781-981-0590 To: EDGES Group From: Alan E.E. Rogers Subject: Meteor scatter rates Since all the World’s designated radio quiet zones are les than 2000 km from strong radio transmitters they are subject to RFI from meteor scatter. The key parameters of meteor scatter are poorly determined. For example, theory suggests that the radar cross-section (RCS) should decrease by 20 dB per decade from head echoes but measurements typically have an even faster decline with frequency. The frequency range for significant scatter and the range of concern to radio astronomy is about 50 to 300 MHz. Some papers claim that 1012 meteors enter the Earth’s atmosphere each day while others suggest a number more like 109. In practice we observed a rate of about 1 per minute when located in a canyon (see memo #52) with sky coverage limited to elevations greater than about 25 degrees. Based on the geometry of Figure 1 this corresponds to a worldwide rate of about 107/day. Figure 2 shows the estimated burst rate as a function of elevation cut-off angle. This very sharp curve shows the advantage of limiting the low elevation response of the antenna or using the terrain to limit the elevation angle. Potential locations for EDGES are on route 205 in the canyon just before 205 enters the Catlow Valley, Oregon or about 1km West of route 205 on Skull creek road. 1 h R To solve: theta=acos( ( (R+ h)*(R+ h)+ R*R-r*r) / (2*(R+ h)*R)) a 1 b -2*R*cos(elev+90) c = -(R+h)*(R+h)+R*R r = ((- b+sqrt(b*b-4*a*c) / (2*a) ; R earth radius = 6357 km r = region where meteors form ions ,-..J 100 km Figure 1. -
Short History of Radio Astronomy Jansky – January 1932
Short History of Radio Astronomy Jansky – January 1932 Modified Bruce Array: Harald Friis design December 1932 Jansky’s 1932 Data Grote Reber- 1937 9.5 m Parabolic Reflector! Strip Chart output From Strip Chart to Contour Plot… 1940 Ap. J. paper…barely Reber’s 160 MHz contour map published in the ApJ in 1944. This shows the northern sky in equatorial coordinates. The Reber’s 160 MHz contour map published in the ApJ in 1944. This shows the northern sky in equatorial coordinates. The Reber’s 160 MHz contour map published in the ApJ in 1944. This shows the northern sky in equatorial coordinates. The Reber’s 160 MHz contour map published in the ApJ in 1944. This shows the northern sky in equatorial coordinates. The Jan Oort & Hendrik van de Hulst Lieden Observatory 1944 Predicted HI Line Detection of Hydrogen Line …… Ewen & Purcell 21 cm HI Line (1420 MHz) Purcell HI Receiver: Doc Ewen (1951) Milky Way in Optical Origin of SETI Nature, 1959 Philip Morrison 1959 Project Ozma: April 6, 1960 Tau Ceti & Epsilon Eridani Cosmic Background: Penzias & Wilson 1965 • 20 ft Echo Horn (Sugar Scoop): • Harald Friis design Pulsars: Bell and Hewish 1967 Detection of Pulsars: ~100ft of chart/day Chart recording of the pulsar Examples of scintillating detection and an interference signal somewhat later in time. Fast chart recording of pulsar emission (LGM nomenclature is “Little Green Arecibo Message: 1974 Big Ear Radio Telescope OSU Wow! Signal, Aug. 15, 1977 Sagitarius, Chi Sagittari star group NRAO 36ft Kitt Peak Telescope The Drake Equation The Drake equation -
CASKAR: a CASPER Concept for the SKA Phase 1 Signal Processing Sub-System
CASKAR: A CASPER concept for the SKA phase 1 Signal Processing Sub-system Francois Kapp, SKA SA Outline • Background • Technical – Architecture – Power • Cost • Schedule • Challenges/Risks • Conclusions Background CASPER Technology MeerKAT Who is CASPER? • Berkeley Wireless Research Center • Nancay Observatory • UC Berkeley Radio Astronomy Lab • Oxford University Astrophysics • UC Berkeley Space Sciences Lab • Metsähovi Radio Observatory, Helsinki University of • Karoo Array Telescope / SKA - SA Technology • NRAO - Green Bank • New Jersey Institute of Technology • NRAO - Socorro • West Virginia University Department of Physics • Allen Telescope Array • University of Iowa Department of Astronomy and • MIT Haystack Observatory Physics • Harvard-Smithsonian Center for Astrophysics • Ohio State University Electroscience Lab • Caltech • Hong Kong University Department of Electrical and Electronic Engineering • Cornell University • Hartebeesthoek Radio Astronomy Observatory • NAIC - Arecibo Observatory • INAF - Istituto di Radioastronomia, Northern Cross • UC Berkeley - Leuschner Observatory Radiotelescope • Giant Metrewave Radio Telescope • University of Manchester, Jodrell Bank Centre for • Institute of Astronomy and Astrophysics, Academia Sinica Astrophysics • National Astronomical Observatories, Chinese Academy of • Submillimeter Array Sciences • NRAO - Tucson / University of Arizona Department of • CSIRO - Australia Telescope National Facility Astronomy • Parkes Observatory • Center for Astrophysics and Supercomputing, Swinburne University -
Next Generation Radio Arrays
NextNext GenerationGeneration RadioRadio ArraysArrays Dr.Dr. FrankFrank D.D. LindLind MITMIT HaystackHaystack ObservatoryObservatory (with acknowledgement to my colleagues who contribute to these efforts...) [McKay-Bukowski, et al., 2014] contact info : Frank D. Lind MIT Haystack Observatory Route 40 Westford MA, 01886 email - [email protected] DeepDeep MemoryMemory Solid state memory capacity will exceed our data storage requirements. Deep memory instruments will become possible. Store all data from every element for the life of a radio array... Intel + Micron 3D Flash Intel XPoint memory Keon Jae Lee of the Korea Advanced Institute of Science and Technology (KAIST) ConnectedConnected WorldWorld Wireless networks will be global and even replace the wires. Disconnected, self networking, and software realized instrumentation Sparse global radio arrays, deployable dense arrays, and ad-hoc arrays DisappearingDisappearing SensorsSensors Integration will become extreme and include quantum referenced sensors Receivers in connectors, cloud computers on a chip, really good clocks Energy harvesting and low power near field wireless data Self coherent arrays, personal passive radar, the ionosphere as a sensor Deployable Low Power Radio Platforms Instruments in ~ 10W power envelopes. Future systems will use ~ 1W of power total. Zero infrastructure radio science instrumentation Software radio and radar technology Solar and battery power Low power computing for data acquisition Intelligent control software Mahali Array (during build out) Deep -
Longterm MWL Behavior of 1ES1959+650
Fakultät Physik – Experimentelle Physik 5 Long-term observations of the TeV blazar 1ES 1959+650 Temporal and spectral behavior in the multi-wavelength context Dissertation zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften (Dr. rer. nat.) vorgelegt von Dipl.-Phys. Michael Backes Dezember 2011 Contents 1 Introduction 1 2 Brief Introduction to Astroparticle Physics 3 2.1 ChargedCosmicRays .............................. 4 2.1.1 CompositionofCosmicRays . 4 2.1.2 EnergySpectrumofCosmicRays. 5 2.1.3 Sources of Cosmic Rays up to 1018 eV................ 6 ∼ 2.1.4 Sources of Cosmic Rays above 1018 eV................ 8 ∼ 2.2 AstrophysicalNeutrinos . ... 12 2.3 PhotonsfromOuterSpace. 13 2.3.1 Leptonic Processes: Connecting Low and High Energy Photons . 13 2.3.2 Hadronic Processes: Connecting Photons, Protons, and Neutrinos . 16 2.4 ActiveGalacticNuclei . 16 2.4.1 Blazars .................................. 17 2.4.2 EmissionModels ............................. 19 2.4.3 BinaryBlackHolesinAGN . 20 3 Instruments for Multi-Wavelength Astronomy 25 3.1 RadioandMicrowave .............................. 25 3.1.1 Single-DishInstruments . 25 3.1.2 Interferometers .............................. 26 3.1.3 Satellites ................................. 27 3.2 Infrared ...................................... 27 3.3 Optical ...................................... 28 3.3.1 Satellite-Born............................... 28 3.3.2 Ground-Based .............................. 28 3.4 Ultraviolet..................................... 29 3.5 X-Rays ..................................... -
History of Radio Astronomy
History of Radio Astronomy Reading for High School Students Getsemary Báez Introduction form of radiation involved (soon known as electro- Radio Astronomy, a field that has strongly magnetic waves). Nevertheless, it was Oliver Heavi- evolved since the end of World War II, has become side who in conjunction with Willard Gibbs in 1884 one of the most important tools of astronomical ob- modified the equations and put them into modern servations. Radio astronomy has been responsible for vector notation. a great part of our understanding of the universe, its A few years later, Heinrich Hertz (1857- formation, composition, interactions, and even pre- 1894) demonstrated the existence of electromagnetic dictions about its future path. This article intends to waves by constructing a device that had the ability to inform the public about the history of radio astron- transmit and receive electromagnetic waves of about omy, its evolution, connection with solar studies, and 5m wavelength. This was actually the first radio the contribution the STEREO/WAVES instrument on wave transmitter, which is what we call today an LC the STEREO spacecraft will have on the study of oscillator. Just like Maxwell’s theory predicted, the this field. waves were polarized. The radiation emissions were detected using a 1mm thin circle of copper wire. Pre-history of Radio Waves Now that there is evidence of electromag- It is almost impossible to depict the most im- netic waves, the physicist Max Planck (1858-1947) portant facts in the history of radio astronomy with- was responsible for a breakthrough in physics that out presenting a sneak peak where everything later developed into the quantum theory, which sug- started, the development and understanding of the gests that energy had to be emitted or absorbed in electromagnetic spectrum. -
Radio Astronomy
Edition of 2013 HANDBOOK ON RADIO ASTRONOMY International Telecommunication Union Sales and Marketing Division Place des Nations *38650* CH-1211 Geneva 20 Switzerland Fax: +41 22 730 5194 Printed in Switzerland Tel.: +41 22 730 6141 Geneva, 2013 E-mail: [email protected] ISBN: 978-92-61-14481-4 Edition of 2013 Web: www.itu.int/publications Photo credit: ATCA David Smyth HANDBOOK ON RADIO ASTRONOMY Radiocommunication Bureau Handbook on Radio Astronomy Third Edition EDITION OF 2013 RADIOCOMMUNICATION BUREAU Cover photo: Six identical 22-m antennas make up CSIRO's Australia Telescope Compact Array, an earth-rotation synthesis telescope located at the Paul Wild Observatory. Credit: David Smyth. ITU 2013 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. - iii - Introduction to the third edition by the Chairman of ITU-R Working Party 7D (Radio Astronomy) It is an honour and privilege to present the third edition of the Handbook – Radio Astronomy, and I do so with great pleasure. The Handbook is not intended as a source book on radio astronomy, but is concerned principally with those aspects of radio astronomy that are relevant to frequency coordination, that is, the management of radio spectrum usage in order to minimize interference between radiocommunication services. Radio astronomy does not involve the transmission of radiowaves in the frequency bands allocated for its operation, and cannot cause harmful interference to other services. On the other hand, the received cosmic signals are usually extremely weak, and transmissions of other services can interfere with such signals. -
Adventures in Radio Astronomy Instrumentation and Signal Processing
Adventures in Radio Astronomy Instrumentation and Signal Processing by Peter Leonard McMahon Submitted to the Department of Electrical Engineering in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering at the University of Cape Town July 2008 Supervisor: Professor Michael Inggs Co-supervisors: Dr Dan Werthimer, CASPER1, University of California, Berkeley Dr Alan Langman, Karoo Array Telescope arXiv:1109.0416v1 [astro-ph.IM] 2 Sep 2011 1Center for Astronomy Signal Processing and Electronics Research Abstract This thesis describes the design and implementation of several instruments for digi- tizing and processing analogue astronomical signals collected using radio telescopes. Modern radio telescopes have significant digital signal processing demands that are typically best met using custom processing engines implemented in Field Pro- grammable Gate Arrays. These demands essentially stem from the ever-larger ana- logue bandwidths that astronomers wish to observe, resulting in large data volumes that need to be processed in real time. We focused on the development of spectrometers for enabling improved pulsar2 sci- ence on the Allen Telescope Array, the Hartebeesthoek Radio Observatory telescope, the Nan¸cay Radio Telescope, and the Parkes Radio Telescope. We also present work that we conducted on the development of real-time pulsar timing instrumentation. All the work described in this thesis was carried out using generic astronomy pro- cessing tools and hardware developed by the Center for Astronomy Signal Processing and Electronics Research (CASPER) at the University of California, Berkeley. We successfully deployed to several telescopes instruments that were built solely with CASPER technology, which has helped to validate the approach to developing radio astronomy instruments that CASPER advocates. -
Selection of Radio Astronomical Observation Sites and Its Dependence on Human Generated RFI
RAA 2014 Vol. 14 No. 2, 241–248 doi: 10.1088/1674–4527/14/2/012 Research in http://www.raa-journal.org http://www.iop.org/journals/raa Astronomy and Astrophysics Selection of radio astronomical observation sites and its dependence on human generated RFI Roslan Umar1;2, Zamri Zainal Abidin1, Zainol Abidin Ibrahim1, Zulfazli Rosli1 and Noorkhallaf Noorazlan1 1 Department of Physics, University of Malaya, 50603, Kuala Lumpur, Malaysia; [email protected] 2 Astronomy Unit, Universiti Sultan Zainal Abidin, 21300, Kuala Terengganu, Malaysia Received 2013 June 7; accepted 2013 October 23 Abstract We investigate the influence of population density on radio-frequency inter- ference (RFI) affecting radio astronomy. We use a new method to quantify the thresh- old of population density in order to determine the most suitable lower limit for site selection of a radio quiet zone (RQZ). We found that there is a certain trend in the population density-RFI graph that increases rapidly at lower values and slows down to almost flat at higher values. We use this trend to identify the thresholds for pop- ulation density that produce RFI. Using this method we found that, for frequencies up to 2.8 GHz, low, medium and high population densities affecting radio astronomy are below 150 ppl km¡2, between 150 ppl km¡2 and 5125 ppl km¡2, and above 5125 ppl km¡2 respectively. We also investigate the effect of population density on the environment of RFI in three astronomical windows, namely the deuterium, hydro- gen and hydroxyl lines. We find that a polynomial fitting to the population density produces a similar trend, giving similar thresholds for the effect of population density. -
NATIONAL SCIENCE FOUNDATION Notice Of
This document is scheduled to be published in the Federal Register on 11/08/2017 and available online at h ttps://federalregister.gov/d/2017-24322, and on FDsys.gov 7555-01-P NATIONAL SCIENCE FOUNDATION Notice of Availability and Notice of Public Meeting for the Draft Environmental Impact Statement (DEIS) for the Green Bank Observatory, Green Bank, West Virginia AGENCY: National Science Foundation. ACTION: Notice of Availability and Notice of Public Meeting. SUMMARY: The National Science Foundation (NSF) has made available for public review and comment the Draft Environmental Impact Statement (DEIS) for Green Bank Observatory. This DEIS has been prepared for the National Science Foundation (NSF) to evaluate the potential environmental impacts resulting from proposed operational changes due to funding constraints for the Green Bank Observatory in Green Bank, West Virginia. The DEIS was prepared in compliance with the National Environmental Policy Act of 1969. Consultation under Section 106 of the National Historic Preservation Act (NHPA) is being conducted concurrent with the NEPA process. DATES: NSF will accept comments on the DEIS for 60 days following publication of this Notice of Availability; an additional 15 days are being provided beyond the standard 45-day review period to allow for the holidays). Comments may be submitted verbally during the public meeting scheduled for November 30, 2017 (see details in SUPPLEMENTARY INFORMATION) or in writing until January 8th, 2018. Substantive comments will be addressed in a Final Environmental