High-Resolution Radio Observations of Submillimetre Galaxies
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Optical SETI: the All-Sky Survey
Professor van der Veen Project Scientist, UCSB Department of Physics, Experimental Cosmology Group class 4 [email protected] frequencies/wavelengths that get through the atmosphere The Planetary Society http://www.planetary.org/blogs/jason-davis/2017/20171025-seti-anybody-out-there.html THE ATMOSPHERE'S EFFECT ON ELECTROMAGNETIC RADIATION Earth's atmosphere prevents large chunks of the electromagnetic spectrum from reaching the ground, providing a natural limit on where ground-based observatories can search for SETI signals. Searching for technology that we have, or are close to having: Continuous radio searches Pulsed radio searches Targeted radio searches All-sky surveys Optical: Continuous laser and near IR searches Pulsed laser searches a hypothetical laser beacon watch now: https://www.youtube.com/watch?time_continue=41&v=zuvyhxORhkI Theoretical physicist Freeman Dyson’s “First Law of SETI Investigations:” Every search for alien civilizations should be planned to give interesting results even when no aliens are discovered. Interview with Carl Sagan from 1978: Start at 6:16 https://www.youtube.com/watch?v=g- Q8aZoWqF0&feature=youtu.be Anomalous signal recorded by Big Ear Telescope at Ohio State University. Big Ear was a flat, aluminum dish three football fields wide, with reflectors at both ends. Signal was at 1,420 MHz, the hydrogen 21 cm ‘spin flip’ line. http://www.bigear.org/Wow30th/wow30th.htm May 15, 2015 A Russian observatory reports a strong signal from a Sun-like star. Possibly from advanced alien civilization. The RATAN-600 radio telescope in Zelenchukskaya, at the northern foot of the Caucasus Mountains location: star HD 164595 G-type star (like our Sun) 94.35 ly away, visually located in constellation Hercules 1 planet that orbits it every 40 days unusual radio signal detected – 11 GHz (2.7 cm) claim: Signal from a Type II Kardashev civilization Only one observation Not confirmed by other telescopes Russian Academy of Sciences later retracted the claim that it was an ETI signal, stating the signal came from a military satellite. -
A Precise and Accurate Determination of the Cosmic Microwave Background Temperature at Z =0.89
A&A 551, A109 (2013) Astronomy DOI: 10.1051/0004-6361/201220613 & c ESO 2013 Astrophysics A precise and accurate determination of the cosmic microwave background temperature at z =0.89 S. Muller1, A. Beelen2,J.H.Black1,S.J.Curran3,4, C. Horellou1,S.Aalto1, F. Combes5, M. Guélin6,7, and C. Henkel8,9 1 Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden e-mail: [email protected] 2 Institut d’Astrophysique Spatiale, Bât. 121, Université Paris-Sud, 91405 Orsay Cedex, France 3 Sydney Institute for Astronomy, School of Physics, The University of Sydney, 2006 NSW, Australia 4 ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), Australia 5 Observatoire de Paris, LERMA, CNRS, 61 Av. de l’Observatoire, 75014 Paris, France 6 Institut de Radioastronomie Millimétrique, 300 rue de la piscine, 38406 Saint-Martin d’Hères, France 7 École Normale Supérieure/LERMA, 24 rue Lhomond, 75005 Paris, France 8 Max-Planck-Institut für Radioastonomie, Auf dem Hügel 69, 53121 Bonn, Germany 9 Astron. Dept., King Abdulaziz University, PO Box 80203, Jeddah, Saudi Arabia Received 22 October 2012 / Accepted 21 December 2012 ABSTRACT Context. According to the Big Bang theory and as a consequence of adiabatic expansion of the Universe, the temperature of the cosmic microwave background (CMB) increases linearly with redshift. This relation is, however, poorly explored, and detection of any deviation would directly lead to (astro-)physics beyond the standard model. Aims. We aim to measure the temperature of the CMB with an accuracy of a few percent at z = 0.89 toward the molecular absorber in the galaxy lensing the quasar PKS 1830−211. -
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 -
Maser Observations with New Instruments
Cosmic Masers - from OH to H0 Proceedings IAU Symposium No. 287, 2012 c 2012 International Astronomical Union E. Humphreys & W. Vlemmings, eds. DOI: 00.0000/X000000000000000X Maser observations with new instruments Alwyn Wootten1 1North American ALMA Science Center, NRAOy, 520 Edgemont Rd., Charlottesville, Virginia 22903, USA email: [email protected] Abstract. The Atacama Large Millimeter/submillimeter Array (ALMA)y, and the Jansky Very Large Array (JVLA) have recently begun probing the Universe. Both provide the largest collect- ing area available at locations on a high dry site, endowing them with unparalleled potential for sensitive spectral line observations. Over the next few years, these telescopes will be joined by other telescopes to provide advances in maser science, including NOEMA and the LMT. Other instruments of note for maser science which may commence construction include the North American Array, the CCAT, and an enlarged worldwide VLB network outfitted to operate into the millimeter wavelength regime. Keywords. masers, radio lines: ISM, instrumentation: high angular resolution 1. Introduction At the last IAU Symposium on masers, construction had just begun on the Atacama Large Millimeter/Submillimeter Array (ALMA), the upgrade of the Very Large Array to the Jansky Very Large Array was being planned, and millimeter instrumentation was being introduced on the Green Bank Telescope (GBT). CARMA had just commenced its first semester of routine science and would shortly populate its more extended arrays, enabling high resolution observations, particularly well adapted to maser observations. The Submillimeter Array was forging new paths with high resolution observations up to the edge of the atmospheric windows near 700 GHz. -
The Merlin - Phase 2
Radio Interferometry: Theory, Techniques and Applications, 381 IAU Coll. 131, ASP Conference Series, Vol. 19, 1991, T.J. Comwell and R.A. Perley (eds.) THE MERLIN - PHASE 2 P.N. WILKINSON University of Manchester, Nuffield Radio Astronomy Laboratories, Jodrell Bank, Macclesfield, Cheshire, SKll 9DL, United Kingdom ABSTRACT The Jodrell Bank MERLIN is currently being upgraded to produce higher sensitivity and higher resolving power. The major capital item has been a new 32m telescope located at MRAO Cambridge which will operate to at least 50 GHz. A brief outline of the upgraded MERLIN and its performance is given. INTRODUCTION The MERLIN (Multi-Element Radio-Linked Interferometer Network), based at Jodrell Bank, was conceived in the mid-1970s and first became operational in 1980. It was a bold concept; no one had made a real-time long-baseline interferometer array with phase-stable local oscillator links before. Six remotely operated telescopes, controlled via telephone lines, are linked to a control computer at Jodrell Bank. The rf signals are transmitted to Jodrell via commercial multi-hop microwave links operating at 7.5 GHz. The local oscillators are coherently slaved to a master oscillator via go-and- return links operating at L-band, the change in the link path-length being taken out in software. This single-frequency L-band link can transfer phase to the equivalent of < 1 picosec (< 0.3 mm of path length) on timescales longer than a few seconds. A detailed description of the MERLIN system has been given by Thomasson (1986). The MERLIN has provided the UK with a unique astronomical facility, one which has made important contributions to extragalactic radio source and OH maser studies. -
Dynamics of the Arecibo Radio Telescope
DYNAMICS OF THE ARECIBO RADIO TELESCOPE Ramy Rashad 110030106 Department of Mechanical Engineering McGill University Montreal, Quebec, Canada February 2005 Under the supervision of Professor Meyer Nahon Abstract The following thesis presents a computer and mathematical model of the dynamics of the tethered subsystem of the Arecibo Radio Telescope. The computer and mathematical model for this part of the Arecibo Radio Telescope involves the study of the dynamic equations governing the motion of the system. It is developed in its various components; the cables, towers, and platform are each modeled in succession. The cable, wind, and numerical integration models stem from an earlier version of a dynamics model created for a different radio telescope; the Large Adaptive Reflector (LAR) system. The study begins by converting the cable model of the LAR system to the configuration required for the Arecibo Radio Telescope. The cable model uses a lumped mass approach in which the cables are discretized into a number of cable elements. The tower motion is modeled by evaluating the combined effective stiffness of the towers and their supporting backstay cables. A drag model of the triangular truss platform is then introduced and the rotational equations of motion of the platform as a rigid body are considered. The translational and rotational governing equations of motion, once developed, present a set of coupled non-linear differential equations of motion which are integrated numerically using a fourth-order Runge-Kutta integration scheme. In this manner, the motion of the system is observed over time. A set of performance metrics of the Arecibo Radio Telescope is defined and these metrics are evaluated under a variety of wind speeds, directions, and turbulent conditions. -
RESEARCH FACILITIES for the SCIENTIFIC COMMUNITY
NATIONAL RADIO ASTRONOMY OBSERVATORY RESEARCH FACILITIES for the SCIENTIFIC COMMUNITY 2020 Atacama Large Millimeter/submillimeter Array Karl G. Jansky Very Large Array Central Development Laboratory Very Long Baseline Array CONTENTS RESEARCH FACILITIES 2020 NRAO Overview.......................................1 Atacama Large Millimeter/submillimeter Array (ALMA).......2 Very Long Baseline Array (VLBA) .........................6 Karl G. Jansky Very Large Array (VLA)......................8 Central Development Laboratory (CDL)..................14 Student & Visitor Programs ..............................16 (above image) One of the five ngVLA Key Science Goals is Using Pulsars in the Galactic Center to Make a Fundamental Test of Gravity. Pulsars in the Galactic Center represent clocks moving in the space-time potential of a super-massive black hole and would enable qualitatively new tests of theories of gravity. More generally, they offer the opportunity to constrain the history of star formation, stellar dynamics, stellar evolution, and the magneto-ionic medium in the Galactic Center. The ngVLA combination of sensitivity and frequency range will enable it to probe much deeper into the likely Galactic Center pulsar population to address fundamental questions in relativity and stellar evolution. Credit: NRAO/AUI/NSF, S. Dagnello (cover) ALMA antennas. Credit: NRAO/AUI/NSF; ALMA, P. Carrillo (back cover) ALMA map of Jupiter showing the distribution of ammonia gas below Jupiter’s cloud deck. Credit: ALMA (ESO/NAOJ/NRAO), I. de Pater et al.; NRAO/AUI NSF, S. Dagnello NRAO Overview ALMA photo courtesy of D. Kordan ALMA photo courtesy of D. The National Radio Astronomy Observatory (NRAO) is delivering transformational scientific capabili- ties and operating three world-class telescopes that are enabling the as- tronomy community to address its highest priority science objectives. -
The Meerkat Radio Telescope Rhodes University SKA South Africa E-Mail: a B Pos(Meerkat2016)001 Justin L
The MeerKAT Radio Telescope PoS(MeerKAT2016)001 Justin L. Jonas∗ab and the MeerKAT Teamb aRhodes University bSKA South Africa E-mail: [email protected] This paper is a high-level description of the development, implementation and initial testing of the MeerKAT radio telescope and its subsystems. The rationale for the design and technology choices is presented in the context of the requirements of the MeerKAT Large-scale Survey Projects. A technical overview is provided for each of the major telescope elements, and key specifications for these components and the overall system are introduced. The results of selected receptor qual- ification tests are presented to illustrate that the MeerKAT receptor exceeds the original design goals by a significant margin. MeerKAT Science: On the Pathway to the SKA, 25-27 May, 2016, Stellenbosch, South Africa ∗Speaker. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). http://pos.sissa.it/ MeerKAT Justin L. Jonas 1. Introduction The MeerKAT radio telescope is a precursor for the Square Kilometre Array (SKA) mid- frequency telescope, located in the arid Karoo region of the Northern Cape Province in South Africa. It will be the most sensitive decimetre-wavelength radio interferometer array in the world before the advent of SKA1-mid. The telescope and its associated infrastructure is funded by the government of South Africa through the National Research Foundation (NRF), an agency of the Department of Science and Technology (DST). Construction and commissioning of the telescope has been the responsibility of the SKA South Africa Project Office, which is a business unit of the PoS(MeerKAT2016)001 NRF. -
Small-Scale Anisotropies of the Cosmic Microwave Background: Experimental and Theoretical Perspectives
Small-Scale Anisotropies of the Cosmic Microwave Background: Experimental and Theoretical Perspectives Eric R. Switzer 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: Lyman Page] November 2008 c Copyright by Eric R. Switzer, 2008. All rights reserved. Abstract In this thesis, we consider both theoretical and experimental aspects of the cosmic microwave background (CMB) anisotropy for ℓ > 500. Part one addresses the process by which the universe first became neutral, its recombination history. The work described here moves closer to achiev- ing the precision needed for upcoming small-scale anisotropy experiments. Part two describes experimental work with the Atacama Cosmology Telescope (ACT), designed to measure these anisotropies, and focuses on its electronics and software, on the site stability, and on calibration and diagnostics. Cosmological recombination occurs when the universe has cooled sufficiently for neutral atomic species to form. The atomic processes in this era determine the evolution of the free electron abundance, which in turn determines the optical depth to Thomson scattering. The Thomson optical depth drops rapidly (cosmologically) as the electrons are captured. The radiation is then decoupled from the matter, and so travels almost unimpeded to us today as the CMB. Studies of the CMB provide a pristine view of this early stage of the universe (at around 300,000 years old), and the statistics of the CMB anisotropy inform a model of the universe which is precise and consistent with cosmological studies of the more recent universe from optical astronomy. -
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. -
The Effect of the Ionosphere on Ultra-Low-Frequency Radio-Interferometric Observations? F
A&A 615, A179 (2018) Astronomy https://doi.org/10.1051/0004-6361/201833012 & © ESO 2018 Astrophysics The effect of the ionosphere on ultra-low-frequency radio-interferometric observations? F. de Gasperin1,2, M. Mevius3, D. A. Rafferty2, H. T. Intema1, and R. A. Fallows3 1 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands e-mail: [email protected] 2 Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany 3 ASTRON – the Netherlands Institute for Radio Astronomy, PO Box 2, 7990 AA Dwingeloo, The Netherlands Received 13 March 2018 / Accepted 19 April 2018 ABSTRACT Context. The ionosphere is the main driver of a series of systematic effects that limit our ability to explore the low-frequency (<1 GHz) sky with radio interferometers. Its effects become increasingly important towards lower frequencies and are particularly hard to calibrate in the low signal-to-noise ratio (S/N) regime in which low-frequency telescopes operate. Aims. In this paper we characterise and quantify the effect of ionospheric-induced systematic errors on astronomical interferometric radio observations at ultra-low frequencies (<100 MHz). We also provide guidelines for observations and data reduction at these frequencies with the LOw Frequency ARray (LOFAR) and future instruments such as the Square Kilometre Array (SKA). Methods. We derive the expected systematic error induced by the ionosphere. We compare our predictions with data from the Low Band Antenna (LBA) system of LOFAR. Results. We show that we can isolate the ionospheric effect in LOFAR LBA data and that our results are compatible with satellite measurements, providing an independent way to measure the ionospheric total electron content (TEC). -
High Resolution Radio Astronomy Using Very Long Baseline Interferometry
IOP PUBLISHING REPORTS ON PROGRESS IN PHYSICS Rep. Prog. Phys. 71 (2008) 066901 (32pp) doi:10.1088/0034-4885/71/6/066901 High resolution radio astronomy using very long baseline interferometry Enno Middelberg1 and Uwe Bach2 1 Astronomisches Institut, Universitat¨ Bochum, 44801 Bochum, Germany 2 Max-Planck-Institut fur¨ Radioastronomie, Auf dem Hugel¨ 69, 53121 Bonn, Germany E-mail: [email protected] and [email protected] Received 3 December 2007, in final form 11 March 2008 Published 2 May 2008 Online at stacks.iop.org/RoPP/71/066901 Abstract Very long baseline interferometry, or VLBI, is the observing technique yielding the highest-resolution images today. Whilst a traditionally large fraction of VLBI observations is concentrating on active galactic nuclei, the number of observations concerned with other astronomical objects such as stars and masers, and with astrometric applications, is significant. In the last decade, much progress has been made in all of these fields. We give a brief introduction to the technique of radio interferometry, focusing on the particularities of VLBI observations, and review recent results which would not have been possible without VLBI observations. This article was invited by Professor J Silk. Contents 1. Introduction 1 2.9. The future of VLBI: eVLBI, VLBI in space and 2. The theory of interferometry and aperture the SKA 10 synthesis 2 2.10. VLBI arrays around the world and their 2.1. Fundamentals 2 capabilities 10 2.2. Sources of error in VLBI observations 7 3. Astrophysical applications 11 2.3. The problem of phase calibration: 3.1. Active galactic nuclei and their jets 12 self-calibration 7 2.4.