PERSISTENT ASYMMETRIC STRUCTURE OF SAGITTARIUS A ON EVENT HORIZON SCALES

Vincent L. Fish; Michael D. Johnson; Sheperd S. Doeleman; Avery E. Broderick; Dimitrios Psaltis; Ru-Sen Lu; Kazunori Akiyama; Walter Alef; Juan Carlos Algaba; Keiichi Asada; Christopher Beaudoin; Alessandra Bertarini; Lindy Blackburn; Ray Blundell; Geoffrey C. Bower; Christiaan Brinkerink; Roger Cappallo; Andrew A. Chael; Richard Chamberlin; Chi-Kwan Chan; Geoffrey B. Crew; Jason Dexter; Matt Dexter; Sergio A. Dzib; Heino Falcke; Robert Freund; Per Friberg; Christopher H. Greer; Mark A. Gurwell; Paul T. P. Ho; Mareki Honma; Makoto Inoue; Tim Johannsen; Junhan Kim; Thomas P. Krichbaum; James Lamb; Jonathan Leon-Tavares; Abraham Loeb; Laurent Loinard; David MacMahon; Daniel P. Marrone; James M. Moran; Monika Moscibrodzka; Gisela N. Ortiz-Leon; Tomoaki Oyama; Feryal Oezel; Richard L. Plambeck; Nicolas Pradel; Rurik A. Primiani; Alan E. E. Rogers; Katherine Rosenfeld; Helge Rottmann; Alan L. Roy; Chester Ruszczyk; Daniel L. Smythe; Jason SooHoo; Justin Spilker; Jordan Stone; Peter Strittmatter; Remo P. J. Tilanus; Michael Titus; Laura Vertatschitsch; Jan Wagner; John F. C. Wardle; Jonathan Weintroub; David Woody; Melvyn Wright; Paul Yamaguchi; Andre Young; Ken H. Young; J. Anton Zensus; Lucy M. Ziurys

doi:10.3847/0004-637X/820/2/90

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PERSISTENT ASYMMETRIC STRUCTURE OF SAGITTARIUS A ON EVENT HORIZON SCALES

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PERSISTENT ASYMMETRIC STRUCTURE OF SAGITTARIUS A ON EVENT HORIZON SCALES

Vincent L. Fish, Michael D. Johnson, Sheperd S. Doeleman, Avery E. Broderick, Dimitrios Psaltis, Ru-Sen Lu, Kazunori Akiyama, Walter Alef, Juan Carlos Algaba, Keiichi Asada, …

The Astrophysical journal, Vol.820(2), pp.90-90

04/01/2016

DOI: https://doi.org/10.3847/0004-637X/820/2/90

Abstract

Astronomy & Astrophysics

Science & Technology

Black Holes

Astronomy

Astrophysics

Radio Astronomy

Physical Sciences

The Galactic Center black hole Sagittarius. A* (Sgr A*) is a prime observing target for the Event Horizon Telescope (EHT), which can resolve the 1.3 mm emission from this source on angular scales comparable to that of the general relativistic shadow. Previous EHT observations have used visibility amplitudes to infer the morphology of the millimeter-wavelength emission. Potentially much richer source information is contained in the phases. We report on 1.3 mm phase information on Sgr. A* obtained with the EHT on a total of 13 observing nights over four years. Closure phases, which are the sum of visibility phases along a closed triangle of interferometer baselines, are used because they are robust against phase corruptions introduced by instrumentation and the rapidly variable atmosphere. The median closure phase on a triangle including telescopes in California, Hawaii, and Arizona is nonzero. This result conclusively demonstrates that the millimeter emission is asymmetric on scales of a few Schwarzschild radii and can be used to break 180 degrees rotational ambiguities inherent from amplitude data alone. The stability of the sign of the closure phase over most observing nights indicates persistent asymmetry in the image of Sgr. A* that is not obscured by refraction due to interstellar electrons along the line of sight.

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Title: PERSISTENT ASYMMETRIC STRUCTURE OF SAGITTARIUS A ON EVENT HORIZON SCALES
Creators: Vincent L. Fish - MIT, Haystack Observ, Route 40, Westford, MA 01886 USA
Michael D. Johnson - Harvard University
Sheperd S. Doeleman - MIT, Haystack Observ, Route 40, Westford, MA 01886 USA
Avery E. Broderick - University of Waterloo
Dimitrios Psaltis - Univ Arizona, Steward Observ, 933 North Cherry Ave, Tucson, AZ 85721 USA
Ru-Sen Lu - Max Planck Society
Kazunori Akiyama - Harvard University
Walter Alef - Max Planck Society
Juan Carlos Algaba - Korea Astron & Space Sci Inst, 776 Daedeokdae Ro, Daejeon 305348, South Korea
Keiichi Asada - Institute of Astronomy and Astrophysics, Academia Sinica
Christopher Beaudoin - MIT, Haystack Observ, Route 40, Westford, MA 01886 USA
Alessandra Bertarini - University of Bonn
Lindy Blackburn - Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA
Ray Blundell - Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA
Geoffrey C. Bower - Academia Sinica
Christiaan Brinkerink - Radboud Univ Nijmegen, Dept Astrophys, IMAPP, POB 9010, NL-6500 GL Nijmegen, Netherlands
Roger Cappallo - MIT, Haystack Observ, Route 40, Westford, MA 01886 USA
Andrew A. Chael - Princeton University
Richard Chamberlin - Max Planck Society
Chi-Kwan Chan - Univ Arizona, Steward Observ, 933 North Cherry Ave, Tucson, AZ 85721 USA
Geoffrey B. Crew - Massachusetts Institute of Technology
Jason Dexter - Harvard University
Matt Dexter - Univ Calif Berkeley, Dept Astron, Radio Astron Lab, 501 Campbell, Berkeley, CA 94720 USA
Sergio A. Dzib - Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany
Heino Falcke - Radboud University Nijmegen
Robert Freund - Univ Arizona, Steward Observ, 933 North Cherry Ave, Tucson, AZ 85721 USA
Per Friberg - James Clerk Maxwell Telescope, East Asia Observ, 660 N Aohoku Pl, Hilo, HI 96720 USA
Christopher H. Greer - AVE
Mark A. Gurwell - Harvard University
Paul T. P. Ho - Acad Sinica, Inst Astron & Astrophys, POB 23-141, Taipei 10617, Taiwan
Mareki Honma - National Astronomical Observatory of Japan
Makoto Inoue - Academia Sinica
Tim Johannsen - Perimeter Inst Theoret Phys, 31 Caroline St North, Waterloo, ON N2L 2Y5, Canada
Junhan Kim - Max Planck Society
Thomas P. Krichbaum - Max Planck Society
James Lamb - CALTECH, Owens Valley Radio Observ, 100 Leighton Lane, Big Pine, CA 93513 USA
Jonathan Leon-Tavares - Ghent University
Abraham Loeb - Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA
Laurent Loinard - Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany
David MacMahon - Univ Calif Berkeley, Dept Astron, Radio Astron Lab, 501 Campbell, Berkeley, CA 94720 USA
Daniel P. Marrone - Univ Arizona, Steward Observ, 933 North Cherry Ave, Tucson, AZ 85721 USA
James M. Moran - Center for Astrophysics Harvard & Smithsonian
Monika Moscibrodzka - Box
Gisela N. Ortiz-Leon - Max
Tomoaki Oyama - National Astronomical Observatory of Japan
Feryal Oezel - AVE
Richard L. Plambeck - Univ Calif Berkeley, Dept Astron, Radio Astron Lab, 501 Campbell, Berkeley, CA 94720 USA
Nicolas Pradel - Auckland Univ Technol, 55 Wellesley St East, Auckland Cent, New Zealand
Rurik A. Primiani - Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA
Alan E. E. Rogers - MIT, Haystack Observ, Route 40, Westford, MA 01886 USA
Katherine Rosenfeld - Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA
Helge Rottmann - Max
Alan L. Roy - Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany
Chester Ruszczyk - Massachusetts Institute of Technology
Daniel L. Smythe - Max Planck Society
Jason SooHoo - Massachusetts Institute of Technology
Justin Spilker - Max Planck Society
Jordan Stone - Nia Association
Peter Strittmatter - Max Planck Society
Remo P. J. Tilanus - Radboud Univ Nijmegen, Dept Astrophys, IMAPP, POB 9010, NL-6500 GL Nijmegen, Netherlands
Michael Titus - MIT, Haystack Observ, Route 40, Westford, MA 01886 USA
Laura Vertatschitsch - Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA
Jan Wagner - Max Planck Society
John F. C. Wardle - Brandeis University, Martin A. Fisher School of Physics
Jonathan Weintroub - Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA
David Woody - CALTECH, Owens Valley Radio Observ, 100 Leighton Lane, Big Pine, CA 93513 USA
Melvyn Wright - Univ Calif Berkeley, Dept Astron, Radio Astron Lab, 501 Campbell, Berkeley, CA 94720 USA
Paul Yamaguchi - Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA
Andre Young - Box
Ken H. Young - Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA
J. Anton Zensus - Max
Lucy M. Ziurys - Univ Arizona, Steward Observ, 933 North Cherry Ave, Tucson, AZ 85721 USA
Publication Details: The Astrophysical journal, Vol.820(2), pp.90-90
Publisher: The American Astronomical Society
Number of pages: 11
Grant note: CARMA partner universities National Science Foundation (NSF) 1207752 / Direct For Mathematical & Physical Scien; National Science Foundation (NSF); NSF - Directorate for Mathematical & Physical Sciences (MPS) Natural Sciences and Engineering Research Council of Canada; Natural Sciences and Engineering Research Council of Canada (NSERC); CGIAR CONACyT, Mexico; Consejo Nacional de Ciencia y Tecnologia (CONACyT) UNAM, Mexico; Universidad Nacional Autonoma de Mexico Perimeter Institute for Theoretical Physics DGAPA, Mexico MEXT/JSPS KAKENHI; Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT); Japan Society for the Promotion of Science; Grants-in-Aid for Scientific Research (KAKENHI) GBMF-3561 / Gordon AMP; Betty Moore Foundation NSF; National Science Foundation (NSF) Government of Canada through Industry Canada 1310896 / Division Of Astronomical Sciences; National Science Foundation (NSF); NSF - Directorate for Mathematical & Physical Sciences (MPS) Province of Ontario through the Ministry of Research and Innovation; Ministry of Research and Innovation, Ontario NSF University Radio Observatories program; National Science Foundation (NSF)
Identifiers: 9924117851201921
Academic Unit: Martin A. Fisher School of Physics
Language: English
Resource Type: Journal article

PERSISTENT ASYMMETRIC STRUCTURE OF SAGITTARIUS A ON EVENT HORIZON SCALES

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