Insights Into the Universe: Astronomy with Haystack's Radio Telescope
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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. -
Aspects of Black Hole Physics
Aspects of Black Hole Physics Andreas Vigand Pedersen The Niels Bohr Institute Academic Advisor: Niels Obers e-mail: [email protected] Abstract: This project examines some of the exact solutions to Einstein’s theory, the theory of linearized gravity, the Komar definition of mass and angular momentum in general relativity and some aspects of (four dimen- sional) black hole physics. The project assumes familiarity with the basics of general relativity and differential geometry, but is otherwise intended to be self contained. The project was written as a ”self-study project” under the supervision of Niels Obers in the summer of 2008. Contents Contents ..................................... 1 Contents ..................................... 1 Preface and acknowledgement ......................... 2 Units, conventions and notation ........................ 3 1 Stationary solutions to Einstein’s equation ............ 4 1.1 Introduction .............................. 4 1.2 The Schwarzschild solution ...................... 6 1.3 The Reissner-Nordstr¨om solution .................. 18 1.4 The Kerr solution ........................... 24 1.5 The Kerr-Newman solution ..................... 28 2 Mass, charge and angular momentum (stationary spacetimes) 30 2.1 Introduction .............................. 30 2.2 Linearized Gravity .......................... 30 2.3 The weak field approximation .................... 35 2.3.1 The effect of a mass distribution on spacetime ....... 37 2.3.2 The effect of a charged mass distribution on spacetime .. 39 2.3.3 The effect of a rotating mass distribution on spacetime .. 40 2.4 Conserved currents in general relativity ............... 43 2.4.1 Komar integrals ........................ 49 2.5 Energy conditions ........................... 53 3 Black holes ................................ 57 3.1 Introduction .............................. 57 3.2 Event horizons ............................ 57 3.2.1 The no-hair theorem and Hawking’s area theorem .... -
Legal "Black Hole"? Extraterritorial State Action and International Treaty Law on Civil and Political Rights
Michigan Journal of International Law Volume 26 Issue 3 2005 Legal "Black Hole"? Extraterritorial State Action and International Treaty Law on Civil and Political Rights Ralph Wilde University of London Follow this and additional works at: https://repository.law.umich.edu/mjil Part of the Human Rights Law Commons, Military, War, and Peace Commons, and the National Security Law Commons Recommended Citation Ralph Wilde, Legal "Black Hole"? Extraterritorial State Action and International Treaty Law on Civil and Political Rights, 26 MICH. J. INT'L L. 739 (2005). Available at: https://repository.law.umich.edu/mjil/vol26/iss3/1 This Article is brought to you for free and open access by the Michigan Journal of International Law at University of Michigan Law School Scholarship Repository. It has been accepted for inclusion in Michigan Journal of International Law by an authorized editor of University of Michigan Law School Scholarship Repository. For more information, please contact [email protected]. LEGAL "BLACK HOLE"? EXTRATERRITORIAL STATE ACTION AND INTERNATIONAL TREATY LAW ON CIVIL AND POLITICAL RIGHTSt Ralph Wilde* I. INTRODUCTION ......................................................................... 740 II. EXTRATERRITORIAL STATE ACTIVITIES ................................... 741 III. THE NEED FOR GREATER SCRUTINY ........................................ 752 A. Ignoring ExtraterritorialActivity ...................................... 753 B. GreaterRisks of Rights Violations in the ExtraterritorialContext .................................................... -
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. -
Arxiv:2010.11303V2 [Astro-Ph.GA] 23 Feb 2021
DRAFT VERSION FEBRUARY 24, 2021 Preprint typeset using LATEX style emulateapj v. 01/23/15 RECONCILING EHT AND GAS DYNAMICS MEASUREMENTS IN M87: IS THE JET MISALIGNED AT PARSEC SCALES? BRITTON JETER1,2,3 ,AVERY E. BRODERICK1,2,3 , 1 Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada 2 Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, ON N2L 2Y5, Canada 3 Waterloo Centre for Astrophysics, University of Waterloo, Waterloo, ON N2L 3G1, Canada Draft version February 24, 2021 ABSTRACT The Event Horizon Telescope mass estimate for M87* is consistent with the stellar dynamics mass estimate and inconsistent with the gas-dynamics mass estimates by up to 2σ. We have previously explored a new gas-dynamics model that incorporated sub-Keplerian gas velocities and could, in principle, explain the discrepancy in the stellar and gas-dynamics mass estimate. In this paper, we extend this gas-dynamical model to also include non-trivial disk heights, which may also resolve the mass discrepancy independent of sub-Keplerian velocity components. By combining the existing velocity measurements and the Event Horizon Telescope mass estimate, we place con- straints on the gas disk inclination and sub-Keplerian fraction. These constraints require the parsec-scale ionized gas disk to be misaligned with the milliarcsecond radio jet by at least 11◦, and more typically 27◦. Modifications to the gas-dynamics model either by introducing sub-Keplerian velocities or thick disks produce further misalign- ment with the radio jet. If the jet is produced in a Blandford–Znajek-type process, the angular momentum of the black hole is decoupled with the angular momentum of the large-scale gas feeding M87*. -
Arxiv:1705.04776V1 [Astro-Ph.HE] 13 May 2017 Aaua M
White Paper on East Asian Vision for mm/submm VLBI: Toward Black Hole Astrophysics down to Angular Resolution of 1 RS Editors Asada, K.1, Kino, M.2,3, Honma, M.3, Hirota, T.3, Lu, R.-S.4,5, Inoue, M.1, Sohn, B.-W.2,6, Shen, Z.-Q.4, and Ho, P. T. P.1,7 Authors Akiyama, K.3,8, Algaba, J-C.2, An, T.4, Bower, G.1, Byun, D-Y.2, Dodson, R.9, Doi, A.10, Edwards, P.G.11, Fujisawa, K.12, Gu, M-F.4, Hada, K.3, Hagiwara, Y.13, Jaroenjittichai, P.15, Jung, T.2,6, Kawashima, T.3, Koyama, S.1,5, Lee, S-S.2, Matsushita, S.1, Nagai, H.3, Nakamura, M.1, Niinuma, K.12, Phillips, C.11, Park, J-H.15, Pu, H-Y.1, Ro, H-W.2,6, Stevens, J.11, Trippe, S.15, Wajima, K.2, Zhao, G-Y.2 1 Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan 2 Korea Astronomy and Space Science Institute, Daedukudae-ro 776, Yuseong-gu, Daejeon 34055, Republic of Korea 3 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan 4 Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, China 5 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, D-53121 Bonn, Germany 6 University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea 7 East Asian Observatory, 660 N. -
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 -
Planetary Data Workshop
NASA Conference Publication 2343 NASA-CP-2343-PT-I 19840026295 Part 1 Planetary Data Workshop Proceedings of a workshop held at Goddard Space Flight Center Greenbelt,. Maryland November 29-December 1, 1983 NI_A NASA Conference Publication 2343 Part 1 Planetary Data Workshop Hugh H. Kieffer, Chairman NASA Office of Space Science and Applications Washington, D.C. Proceedings of a workshop held at Goddard Space Hight Center Greenbelt, Maryland November 29-December l, 1983 N/_A National Aeronautics and Space Administration ScientificandTechnical Information Branch 1984 Contributing Authors Hugh Kieffer U.S. Geological Survey Raymond E. Arvidson Washington University William A° Baum Lowell Observatory Larry Bolef Washington University Larry H. Brace Goddard Space Flight Center Roger N. Clark University of Colorado Randal Davis University of Colorado Richard Elphic University of California - Los Angeles John Pearl Goddard Space Flight Center Chris Russell University of California - Los Angeles Stephen R. Saunders Jet Propulsion Laboratory Richard A. Simpson Stanford University William Smythe Jet Propulsion Laboratory Laurence A. Soderblom California Institute of Technology I. A. Stewart University of Colorado R. J. Walker University of California - Los Angeles Charles Acton Jet Propulsion Laboratory Isadore Adler University of Maryland Joseph K. Alexander Goddard Space Flight Center Donald E. Anderson Naval Research Laboratory Donald L. Anderson Arizona State University John Anderson Jet Propulsion Laboratory Daniel Baker Los Alamos National Laboratory Edwin S. Barker McDonald Observatory Reta F. Beebe New Mexico State University Jay T. Bergstralh Jet Propulsion Laboratory Michael L. Bielefield Space Telescope Science Institute A. Lyle Broadfoot University of Arizona James Brown Donald B. Campbell Arecibo Observatory G. -
Active Galactic Nuclei
Active Galactic Nuclei • Optical spectra, distance, line width • Varieties of AGN and unified scheme • Variability and lifetime • Black hole mass and growth • Geometry: disk, BLR, NLR • Reverberation mapping • Jets and blazars • AGN spectra Optical spectrum of an AGN • Variety of different emission lines • Each line has centroid, area, width • There is also continuum emission Emission lines • Shift of line centroid gives recession velocity v/c = Δλ/λ. • The width is usually characterized by the “Full Width at Half Maximum”. For a Gaussian FHWM = 2.35σ. • The line width is determined by the velocity distribution of the line emitting gas, Δv/c = σ/λ. • Area is proportional to the number of detected line photons or the line flux. • Usually characterized by “equivalent width” or range in wavelength over which integration of the continuum produces the same flux as the line. Early observations of AGN • Very wide emission lines have been known since 1908. • In 1959, Woltjer noted that if the profiles are due to Doppler motion and the gas is gravitationally bound then v2 ~ GM/r. For v ~ 2000 km/s, we have 10 r M ≥10 ( 100 pc ) M Sun • So AGN, known at the time as Seyfert galaxies, must either have a very compact and luminous nucleus or be very massive. Quasars • Early radio telescopes found radio emission from stars, nebulae, and some galaxies. • There were also point-like, or star-like, radio sources which varied rapidly these are the `quasi-stellar’ radio sources or quasars. • In visible light quasars appear as points, like stars. Quasar optical spectra Redshift of 3C273 is 0.16. -
The Third Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope M
The Astrophysical Journal, 810:14 (34pp), 2015 September 1 doi:10.1088/0004-637X/810/1/14 © 2015. The American Astronomical Society. All rights reserved. THE THIRD CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE M. Ackermann1, M. Ajello2, W. B. Atwood3, L. Baldini4, J. Ballet5, G. Barbiellini6,7, D. Bastieri8,9, J. Becerra Gonzalez10,11, R. Bellazzini12, E. Bissaldi13, R. D. Blandford14, E. D. Bloom14, R. Bonino15,16, E. Bottacini14, T. J. Brandt10, J. Bregeon17, R. J. Britto18, P. Bruel19, R. Buehler1, S. Buson8,9, G. A. Caliandro14,20, R. A. Cameron14, M. Caragiulo13, P. A. Caraveo21, B. Carpenter10,22, J. M. Casandjian5, E. Cavazzuti23, C. Cecchi24,25, E. Charles14, A. Chekhtman26, C. C. Cheung27, J. Chiang14, G. Chiaro9, S. Ciprini23,24,28, R. Claus14, J. Cohen-Tanugi17, L. R. Cominsky29, J. Conrad30,31,32,70, S. Cutini23,24,28,R.D’Abrusco33,F.D’Ammando34,35, A. de Angelis36, R. Desiante6,37, S. W. Digel14, L. Di Venere38, P. S. Drell14, C. Favuzzi13,38, S. J. Fegan19, E. C. Ferrara10, J. Finke27, W. B. Focke14, A. Franckowiak14, L. Fuhrmann39, Y. Fukazawa40, A. K. Furniss14, P. Fusco13,38, F. Gargano13, D. Gasparrini23,24,28, N. Giglietto13,38, P. Giommi23, F. Giordano13,38, M. Giroletti34, T. Glanzman14, G. Godfrey14, I. A. Grenier5, J. E. Grove27, S. Guiriec10,2,71, J. W. Hewitt41,42, A. B. Hill14,43,68, D. Horan19, R. Itoh40, G. Jóhannesson44, A. S. Johnson14, W. N. Johnson27, J. Kataoka45,T.Kawano40, F. Krauss46, M. Kuss12, G. La Mura9,47, S. Larsson30,31,48, L. -
Counting Gamma Rays in the Directions of Galaxy Clusters
A&A 567, A93 (2014) Astronomy DOI: 10.1051/0004-6361/201322454 & c ESO 2014 Astrophysics Counting gamma rays in the directions of galaxy clusters D. A. Prokhorov1 and E. M. Churazov1,2 1 Max Planck Institute for Astrophysics, Karl-Schwarzschild-Strasse 1, 85741 Garching, Germany e-mail: [email protected] 2 Space Research Institute (IKI), Profsouznaya 84/32, 117997 Moscow, Russia Received 6 August 2013 / Accepted 19 May 2014 ABSTRACT Emission from active galactic nuclei (AGNs) and from neutral pion decay are the two most natural mechanisms that could establish a galaxy cluster as a source of gamma rays in the GeV regime. We revisit this problem by using 52.5 months of Fermi-LAT data above 10 GeV and stacking 55 clusters from the HIFLUCGS sample of the X-ray brightest clusters. The choice of >10 GeV photons is optimal from the point of view of angular resolution, while the sample selection optimizes the chances of detecting signatures of neutral pion decay, arising from hadronic interactions of relativistic protons with an intracluster medium, which scale with the X-ray flux. In the stacked data we detected a signal for the central 0.25 deg circle at the level of 4.3σ. Evidence for a spatial extent of the signal is marginal. A subsample of cool-core clusters has a higher count rate of 1.9 ± 0.3 per cluster compared to the subsample of non-cool core clusters at 1.3 ± 0.2. Several independent arguments suggest that the contribution of AGNs to the observed signal is substantial, if not dominant. -
Mapping Prostitution: Sex, Space, Taxonomy in the Fin- De-Siècle French Novel
Mapping Prostitution: Sex, Space, Taxonomy in the Fin- de-Siècle French Novel The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Tanner, Jessica Leigh. 2013. Mapping Prostitution: Sex, Space, Taxonomy in the Fin-de-Siècle French Novel. Doctoral dissertation, Harvard University. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:10947429 Terms of Use This article was downloaded from Harvard University’s DASH repository, WARNING: This file should NOT have been available for downloading from Harvard University’s DASH repository. Mapping Prostitution: Sex, Space, Taxonomy in the Fin-de-siècle French Novel A dissertation presented by Jessica Leigh Tanner to The Department of Romance Languages and Literatures in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Romance Languages and Literatures Harvard University Cambridge, Massachusetts May 2013 © 2013 – Jessica Leigh Tanner All rights reserved. Dissertation Advisor: Professor Janet Beizer Jessica Leigh Tanner Mapping Prostitution: Sex, Space, Taxonomy in the Fin-de-siècle French Novel Abstract This dissertation examines representations of prostitution in male-authored French novels from the later nineteenth century. It proposes that prostitution has a map, and that realist and naturalist authors appropriate this cartography in the Second Empire and early Third Republic to make sense of a shifting and overhauled Paris perceived to resist mimetic literary inscription. Though always significant in realist and naturalist narrative, space is uniquely complicit in the novel of prostitution due to the contemporary policy of reglementarism, whose primary instrument was the mise en carte: an official registration that subjected prostitutes to moral and hygienic surveillance, but also “put them on the map,” classifying them according to their space of practice (such as the brothel or the boulevard).