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.

black hole physics

techniques: interferometric

galaxies: jets

techniques: high angular resolution

galaxies: individual (M87, 3C279)

Author

The Event Horizon Telescope Collaboration

Kazunori Akiyama

National Radio Astronomy Observatory

National Astronomical Observatory of Japan

Harvard University

Massachusetts Institute of Technology (MIT)

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

Chinese Academy of Sciences

Shanghai Astronomical Observatory

I. Cho

University of Science and Technology (UST)

Korea Astronomy and Space Science Institute

Pierre Christian

University of Arizona

Harvard-Smithsonian Center for Astrophysics

John Conway

Chalmers, Space, Earth and Environment, Onsala Space Observatory

James M. Cordes

Cornell University

G. Crew

Massachusetts Institute of Technology (MIT)

Yuzhu Cui

The Graduate University for Advanced Studies (SOKENDAI)

National Astronomical Observatory of Japan

Jordy Davelaar

Radboud University

Mariafelicia De Laurentis

Goethe University Frankfurt

University of Naples Federico II

National Institute for Nuclear Physics

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

National Astronomical Observatory of Japan

The Graduate University for Advanced Studies (SOKENDAI)

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

The Institute of Statistical Mathematics

National Astronomical Observatory of Japan

University of Tokyo

The Graduate University for Advanced Studies (SOKENDAI)

Makoto Inoue

National Taiwan University

S. Issaoun

Radboud University

David J. James

Harvard University

Harvard-Smithsonian Center for Astrophysics

Buell T. Jannuzi

University of Arizona

M. Janßen

Radboud University

Britton Jeter

University of Waterloo

Wu Jiang

Shanghai Astronomical Observatory

Michael D. Johnson

Harvard University

Harvard-Smithsonian Center for Astrophysics

S.G. Jorstad

Boston University

Saint Petersburg State University - Spsu

Taehyun Jung

Korea Astronomy and Space Science Institute

University of Science and Technology (UST)

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 L3

Subject Categories

Subatomic Physics

Astronomy, Astrophysics and Cosmology

Geosciences, Multidisciplinary

DOI

10.3847/2041-8213/ab0c57

More information

Latest update

4/1/2021 1