SYMBA: An end-to-end VLBI synthetic data generation pipeline

Simulating Event Horizon Telescope observations of M 87

¹ Department of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University, PO Box 9010, 6500 GL Nijmegen, The Netherlands
e-mail: f.roelofs@astro.ru.nl
² Centre for Radio Astronomy Techniques and Technologies, Department of Physics and Electronics, Rhodes University, Grahamstown 6140, South Africa
³ Department of Physics, University of Pretoria, Lynnwood Road, Hatfield, Pretoria 0083, South Africa
⁴ Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
⁵ Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
⁶ Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
⁷ Black Hole Initiative at Harvard University, 20 Garden Street, Cambridge, MA 02138, USA
⁸ California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
⁹ Leiden Observatory–Allegro, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
¹⁰ Netherlands Organisation for Scientific Research (NWO), Postbus 93138, 2509 AC Den Haag, The Netherlands
¹¹ Joint Institute for VLBI ERIC (JIVE), Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
¹² National Radio Astronomy Observatory, 520 Edgemont Rd, Charlottesville, VA 22903, USA
¹³ Massachusetts Institute of Technology Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USA
¹⁴ National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
¹⁵ Instituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
¹⁶ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
¹⁷ Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No. 1, Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan ROC
¹⁸ Departament d’Astronomia i Astrofísica, Universitat de València, C. Dr. Moliner 50, 46100 Burjassot, València, Spain
¹⁹ Observatori Astronómic, Universitat de València, C. Catedrático José Beltrán 2, 46980 Paterna, València, Spain
²⁰ Steward Observatory and Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USA
²¹ East Asian Observatory, 660 N. A’ohoku Place, Hilo, HI 96720, USA
²² Nederlandse Onderzoekschool voor Astronomie (NOVA), PO Box 9513, 2300 RA Leiden, The Netherlands
²³ Institute of Astronomy and Astrophysics, Academia Sinica, 645 N. A’ohoku Place, Hilo, HI 96720, USA
²⁴ Institut de Radioastronomie Millimétrique, 300 Rue de la Piscine, 38406 Saint Martin d’Hères, France
²⁵ Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, ON N2L 2Y5, Canada
²⁶ Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
²⁷ Waterloo Centre for Astrophysics, University of Waterloo, Waterloo, ON N2L 3G1, Canada
²⁸ Korea Astronomy and Space Science Institute, Daedeok-daero 776, Yuseong-gu, Daejeon 34055, Republic of Korea
²⁹ University of Science and Technology, Gajeong-ro 217, Yuseong-gu, Daejeon 34113, Republic of Korea
³⁰ Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
³¹ Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
³² Department of Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
³³ Enrico Fermi Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
³⁴ Princeton Center for Theoretical Science, Jadwin Hall, Princeton University, Princeton, NJ 08544, USA
³⁵ Data Science Institute, University of Arizona, 1230 N. Cherry Ave., Tucson, AZ 85721, USA
³⁶ Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY 14853, USA
³⁷ Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PR China
³⁸ Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Nanjing 210008, PR China
³⁹ Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 43992 Onsala, Sweden
⁴⁰ Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshigaoka, Mizusawa, Oshu, Iwate 023-0861, Japan
⁴¹ Department of Astronomical Science, The Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
⁴² Dipartimento di Fisica “E. Pancini”, Universitá di Napoli “Federico II”, Compl. Univ. di Monte S. Angelo, Edificio G, Via Cinthia, 80126 Napoli, Italy
⁴³ INFN Sez. di Napoli, Compl. Univ. di Monte S. Angelo, Edificio G, Via Cinthia, 80126 Napoli, Italy
⁴⁴ Department of History of Science, Harvard University, Cambridge, MA 02138, USA
⁴⁵ Department of Physics, Harvard University, Cambridge, MA 02138, USA
⁴⁶ Department of Physics, University of Illinois, 1110 West Green St, Urbana, IL 61801, USA
⁴⁷ Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801, USA
⁴⁸ Key Laboratory for Research in Galaxies and Cosmology, Chinese Academy of Sciences, Shanghai 200030, PR China
⁴⁹ NOVA Sub-mm Instrumentation Group, Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen, The Netherlands
⁵⁰ Department of Astronomy, School of Physics, Peking University, Beijing 100871, PR China
⁵¹ Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, PR China
⁵² Instituto Nacional de Astrofísica, Óptica y Electrónica. Apartado Postal 51 y 216, 72000 Puebla Pue., Mexico
⁵³ The Institute of Statistical Mathematics, 10-3 Midori-cho, Tachikawa, Tokyo 190-8562, Japan
⁵⁴ Department of Statistical Science, The Graduate University for Advanced Studies (SOKENDAI), 10-3 Midori-cho, Tachikawa, Tokyo 190-8562, Japan
⁵⁵ Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8583, Japan
⁵⁶ Institute for Astrophysical Research, Boston University, 725 Commonwealth Ave., Boston, MA 02215, USA
⁵⁷ Astronomical Institute, St. Petersburg University, Universitetskij pr., 28, Petrodvorets, 198504 St. Petersburg, Russia
⁵⁸ Kogakuin University of Technology & Engineering, Academic Support Center, 2665-1 Nakano, Hachioji, Tokyo 192-0015, Japan
⁵⁹ Physics Department, National Sun Yat-Sen University, No. 70, Lien-Hai Rd, Kaosiung City 80424, Taiwan ROC
⁶⁰ National Optical Astronomy Observatory, 950 North Cherry Ave., Tucson, AZ 85719, USA
⁶¹ Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Shijingshan District, Beijing, PR China
⁶² School of Astronomy and Space Science, Nanjing University, Nanjing 210023, PR China
⁶³ Key Laboratory of Modern Astronomy and Astrophysics, Nanjing University, Nanjing 210023, PR China
⁶⁴ Italian ALMA Regional Centre, INAF-Istituto di Radioastronomia, Via P. Gobetti 101, 40129 Bologna, Italy
⁶⁵ Department of Physics, National Taiwan University, No.1, Sect.4, Roosevelt Rd., Taipei 10617, Taiwan ROC
⁶⁶ Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Morelia 58089, Mexico
⁶⁷ Instituto de Astronomía, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico
⁶⁸ Yunnan Observatories, Chinese Academy of Sciences, 650011 Kunming, Yunnan Province, PR China
⁶⁹ Center for Astronomical Mega-Science, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, PR China
⁷⁰ Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, 650011 Kunming, PR China
⁷¹ Gravitation Astroparticle Physics Amsterdam (GRAPPA) Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
⁷² Astronomy Department, Universidad de Concepción, Casilla 160-C, Concepción, Chile
⁷³ Department of Astronomy, University of Massachusetts, 01003 Amherst, MA, USA
⁷⁴ Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
⁷⁵ Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8, Canada
⁷⁶ Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada
⁷⁷ Canadian Institute for Advanced Research, 180 Dundas St West, Toronto, ON M5G 1Z8, Canada
⁷⁸ Radio Astronomy Laboratory, University of California, Berkeley, CA 94720, USA
⁷⁹ Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544, USA
⁸⁰ Center for Computational Astrophysics, Flatiron Institute, 162 Fifth Avenue, New York, NY 10010, USA
⁸¹ CCS-2, Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545, USA
⁸² Center for Theoretical Astrophysics, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
⁸³ Instituto de Radioastronomía Milimétrica, IRAM, Avenida Divina Pastora 7, Local 20, 18012 Granada, Spain
⁸⁴ Consejo Nacional de Ciencia y Tecnología, Av. Insurgentes Sur 1582, 03940 Ciudad de México, Mexico
⁸⁵ Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
⁸⁶ Aalto University Department of Electronics and Nanoengineering, PL 15500, 00076 Aalto, Finland
⁸⁷ Aalto University Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
⁸⁸ Department of Astronomy, Yonsei University, Yonsei-ro 50, Seodaemun-gu, 03722 Seoul, Republic of Korea
⁸⁹ Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan
⁹⁰ Astronomical Institute, Tohoku University, Sendai 980-8578, Japan
⁹¹ Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 08826, Republic of Korea
⁹² Leiden Observatory, Leiden University, Postbus 2300, 9513 RA Leiden, The Netherlands
⁹³ Physics Department, Brandeis University, 415 South Street, Waltham, MA 02453, USA
⁹⁴ School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
⁹⁵ Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
⁹⁶ School of Astronomy and Space Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, PR China
⁹⁷ Astronomy Department, University of Science and Technology of China, Hefei 230026, PR China
⁹⁸ CP3-Origins, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
⁹⁹ School of Natural Sciences, Institute for Advanced Study, 1 Einstein Drive, Princeton, NJ 08540, USA

Received: 3 September 2019
Accepted: 18 October 2019

Abstract

Context. Realistic synthetic observations of theoretical source models are essential for our understanding of real observational data. In using synthetic data, one can verify the extent to which source parameters can be recovered and evaluate how various data corruption effects can be calibrated. These studies are the most important when proposing observations of new sources, in the characterization of the capabilities of new or upgraded instruments, and when verifying model-based theoretical predictions in a direct comparison with observational data.

Aims. We present the SYnthetic Measurement creator for long Baseline Arrays (SYMBA), a novel synthetic data generation pipeline for Very Long Baseline Interferometry (VLBI) observations. SYMBA takes into account several realistic atmospheric, instrumental, and calibration effects.

Methods. We used SYMBA to create synthetic observations for the Event Horizon Telescope (EHT), a millimetre VLBI array, which has recently captured the first image of a black hole shadow. After testing SYMBA with simple source and corruption models, we study the importance of including all corruption and calibration effects, compared to the addition of thermal noise only. Using synthetic data based on two example general relativistic magnetohydrodynamics (GRMHD) model images of M 87, we performed case studies to assess the image quality that can be obtained with the current and future EHT array for different weather conditions.

Results. Our synthetic observations show that the effects of atmospheric and instrumental corruptions on the measured visibilities are significant. Despite these effects, we demonstrate how the overall structure of our GRMHD source models can be recovered robustly with the EHT2017 array after performing calibration steps, which include fringe fitting, a priori amplitude and network calibration, and self-calibration. With the planned addition of new stations to the EHT array in the coming years, images could be reconstructed with higher angular resolution and dynamic range. In our case study, these improvements allowed for a distinction between a thermal and a non-thermal GRMHD model based on salient features in reconstructed images.