First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole
Abstract
Abstract We present the first Event Horizon Telescope (EHT) images of M87, using observations from April 2017 at 1.3 mm wavelength. These images show a prominent ring with a diameter of ∼40 μ as, consistent with the size and shape of the lensed photon orbit encircling the “shadow” of a supermassive black hole. The ring is persistent across four observing nights and shows enhanced brightness in the south. To assess the reliability of these results, we implemented a two-stage imaging procedure. In the first stage, four teams, each blind to the others’ work, produced images of M87 using both an established method (CLEAN) and a newer technique (regularized maximum likelihood). This stage allowed us to avoid shared human bias and to assess common features among independent reconstructions. In the second stage, we reconstructed synthetic data from a large survey of imaging parameters and then compared the results with the corresponding ground truth images. This stage allowed us to select parameters objectively to use when reconstructing images of M87. Across all tests in both stages, the ring diameter and asymmetry remained stable, insensitive to the choice of imaging technique. We describe the EHT imaging procedures, the primary image features in M87, and the dependence of these features on imaging assumptions.
Funding
- National Science Foundation
- Smithsonian Institution
- U.S. Department of Energy
- National Aeronautics and Space Administration
- John Templeton Foundation
- Gordon and Betty Moore Foundation
- Kavli Foundation
- Harvard University
- University of Chicago
- University of Arizona
- Innovation, Science and Economic Development Canada
- Compute Canada
- Ministerio de Ciencia, Innovación y Universidades
- National Radio Astronomy Observatory
- Associated Universities
- International Max Planck Research School for Environmental, Cellular and Molecular Microbiology
- Government of Canada
- Leverhulme Trust
- European Commission
- National Research Foundation
- Department of Science and Technology, Ministry of Science and Technology, India
- Ministry of Education, Culture, Sports, Science and Technology
- National Natural Science Foundation of China
- Academia Sinica
- Academy of Finland
- Chinese Academy of Sciences
- Consejo Nacional de Ciencia y Tecnología
- Nederlandse Organisatie voor Wetenschappelijk Onderzoek
- Ministerio de Economía y Competitividad
- Generalitat Valenciana
- Nuclear Safety and Security Commission
- Korea Institute of Science and Technology
- Korea Institute of Science and Technology Information
- Korea Astronomy and Space Science Institute
- National Research Foundation of Korea
- Max-Planck-Gesellschaft
- Vetenskapsrådet
- China Scholarship Council
- European Southern Observatory
- Centre National de la Recherche Scientifique
- Universidad Nacional Autónoma de México
- National Astronomical Observatory of Japan
- Russian Science Foundation
- Ministero dello Sviluppo Economico
- Iran Telecommunication Research Center
- Recruitment Program of Global Experts
- Istituto Nazionale di Fisica Nucleare
- Instituto de Astrofísica de Andalucía
- Institut Périmètre de physique théorique
- Korea Research Environment Open Network
- Toray Science Foundation
- National Nuclear Security Administration
- Natural Sciences and Engineering Research Council of Canada
- Japan Society for the Promotion of Science
- Comisión Nacional de Investigación Científica y Tecnológica
- Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México
- National Institutes of Natural Sciences
- National Key Research and Development Program of China
- National Institute of Information and Communications Technology
- Office of International Science and Engineering
- Los Alamos National Laboratory
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