First M87 Event Horizon Telescope Results. III. Data Processing and Calibration
Journal article, 2019
We present the calibration and reduction of Event Horizon Telescope (EHT) 1.3 mm radio wavelength observations of the supermassive black hole candidate at the center of the radio galaxy M87 and the quasar 3C 279, taken during the 2017 April 5-11 observing campaign. These global very long baseline interferometric observations include for the first time the highly sensitive Atacama Large Millimeter/submillimeter Array (ALMA); reaching an angular resolution of 25 μas, with characteristic sensitivity limits of ∼1 mJy on baselines to ALMA and ∼10 mJy on other baselines. The observations present challenges for existing data processing tools, arising from the rapid atmospheric phase fluctuations, wide recording bandwidth, and highly heterogeneous array. In response, we developed three independent pipelines for phase calibration and fringe detection, each tailored to the specific needs of the EHT. The final data products include calibrated total intensity amplitude and phase information. They are validated through a series of quality assurance tests that show consistency across pipelines and set limits on baseline systematic errors of 2% in amplitude and 1° in phase. The M87 data reveal the presence of two nulls in correlated flux density at ∼3.4 and ∼8.3 Gλ and temporal evolution in closure quantities, indicating intrinsic variability of compact structure on a timescale of days, or several light-crossing times for a few billion solar-mass black hole. These measurements provide the first opportunity to image horizon-scale structure in M87.
techniques: interferometric
black hole physics
galaxies: individual (M87, 3C279)
galaxies: jets
techniques: high angular resolution
Author
Kazunori Akiyama
National Astronomical Observatory of Japan
Massachusetts Institute of Technology (MIT)
National Radio Astronomy Observatory
Harvard University
Antxon Alberdi
Institute of Astrophysics of Andalusia (IAA)
Walter Alef
Max Planck Society
K. Asada
National Taiwan University
R. Azulay
Universitat de Valencia
Max Planck Society
A. K. Baczko
Max Planck Society
David Ball
University of Arizona
Mislav Baloković
Harvard-Smithsonian Center for Astrophysics
Harvard University
John Barrett
Massachusetts Institute of Technology (MIT)
Dan Bintley
East Asian Observatory
Lindy Blackburn
Harvard University
Harvard-Smithsonian Center for Astrophysics
W. Boland
Nederlandse Onderzoekschool voor Astronomie (NOVA)
K. L. Bouman
Harvard University
Harvard-Smithsonian Center for Astrophysics
California Institute of Technology (Caltech)
G. C. Bower
Academia Sinica
M. Bremer
Institut de Radioastronomie Millimétrique (IRAM)
C. D. Brinkerink
Radboud University
Roger Brissenden
Harvard-Smithsonian Center for Astrophysics
Harvard University
Silke Britzen
Max Planck Society
Avery E. Broderick
Perimeter Institute for Theoretical Physics
University of Waterloo
D. Broguière
Institut de Radioastronomie Millimétrique (IRAM)
Thomas Bronzwaer
Radboud University
Do Young Byun
University of Science and Technology (UST)
Korea Astronomy and Space Science Institute
J. E. Carlstrom
University of Chicago
A. Chael
Harvard University
Harvard-Smithsonian Center for Astrophysics
Chi Kwan Chan
University of Arizona
S. Chatterjee
Cornell University
Koushik Chatterjee
University of Amsterdam
Ming Tang Chen
Academia Sinica
Yongjun Chen
Shanghai Astronomical Observatory
Chinese Academy of Sciences
I. Cho
University of Science and Technology (UST)
Korea Astronomy and Space Science Institute
Pierre Christian
Harvard-Smithsonian Center for Astrophysics
University of Arizona
John Conway
Chalmers, Space, Earth and Environment, Onsala Space Observatory
James M. Cordes
Cornell University
G. Crew
Massachusetts Institute of Technology (MIT)
Yuzhu Cui
National Astronomical Observatory of Japan
The Graduate University for Advanced Studies (SOKENDAI)
Jordy Davelaar
Radboud University
Mariafelicia De Laurentis
University of Naples Federico II
National Institute for Nuclear Physics
Goethe University Frankfurt
R. P. Deane
University of Pretoria
Rhodes University
Jessica Dempsey
East Asian Observatory
Gregory Desvignes
Max Planck Society
Jason Dexter
Max Planck Society
S. Doeleman
Harvard-Smithsonian Center for Astrophysics
Harvard University
Ralph P. Eatough
Max Planck Society
H.D. Falcke
Radboud University
V. Fish
Massachusetts Institute of Technology (MIT)
E. Fomalont
National Radio Astronomy Observatory
R. Fraga-Encinas
Radboud University
P. Friberg
East Asian Observatory
Christian M. Fromm
Goethe University Frankfurt
J. L. Gomez
Institute of Astrophysics of Andalusia (IAA)
Peter Galison
Harvard University
Charles F. Gammie
University of Illinois
Roberto Garcia
Institut de Radioastronomie Millimétrique (IRAM)
Olivier Gentaz
Institut de Radioastronomie Millimétrique (IRAM)
Boris Georgiev
University of Waterloo
C. Goddi
Radboud University
Leiden University
R. Gold
Goethe University Frankfurt
Minfeng Gu
Chinese Academy of Sciences
Shanghai Astronomical Observatory
M. Gurwell
Harvard-Smithsonian Center for Astrophysics
K. Hada
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
Michael H. Hecht
Massachusetts Institute of Technology (MIT)
R. Hesper
University of Groningen
Luis C. Ho
Beijing University of Technology
Paul Ho
National Taiwan University
Mareki Honma
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
Chih Wei L. Huang
National Taiwan University
Lei Huang
Chinese Academy of Sciences
Shanghai Astronomical Observatory
D. Hughes
National Institute of Astrophysics, Optics and Electronics
Shiro Ikeda
National Astronomical Observatory of Japan
The Institute of Statistical Mathematics
University of Tokyo
The Graduate University for Advanced Studies (SOKENDAI)
Makoto Inoue
National Taiwan University
S. Issaoun
Radboud University
David J. James
Harvard-Smithsonian Center for Astrophysics
Harvard University
Buell T. Jannuzi
University of Arizona
M. Janßen
Radboud University
Britton Jeter
University of Waterloo
Wu Jiang
Shanghai Astronomical Observatory
Michael D. Johnson
Harvard-Smithsonian Center for Astrophysics
Harvard University
S.G. Jorstad
Saint Petersburg State University - Spsu
Boston University
Taehyun Jung
University of Science and Technology (UST)
Korea Astronomy and Space Science Institute
Mansour Karami
University of Waterloo
Perimeter Institute for Theoretical Physics
R. Karuppusamy
Max Planck Society
Tomohisa Kawashima
National Astronomical Observatory of Japan
G. Keating
Harvard-Smithsonian Center for Astrophysics
M. M. Kettenis
Joint Institute for VLBI in Europe (JIVE)
Jae Young Kim
Max Planck Society
Junhan Kim
University of Arizona
Jongsoo Kim
Korea Astronomy and Space Science Institute
M. Kino
National Astronomical Observatory of Japan
Kogakuin University of Technology and Engineering
Jun Yi Koay
National Taiwan University
Patrick M. Koch
National Taiwan University
Shoko Koyama
National Taiwan University
M. Kramer
Max Planck Society
C. Kramer
Institut de Radioastronomie Millimétrique (IRAM)
T.P. Krichbaum
Max Planck Society
Cheng Yu Kuo
National Sun Yat-Sen University
Tod R. Lauer
National Optical Astronomy Observatory
Sang Sung Lee
Korea Astronomy and Space Science Institute
Yan Rong Li
Chinese Academy of Sciences
Zhiyuan Li
Nanjing University
Astrophysical Journal Letters
2041-8205 (ISSN) 2041-8213 (eISSN)
Vol. 875 1 L3Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.3847/2041-8213/ab0c57