Broadband multi-wavelength properties of M87 during the 2018 EHT campaign including a very high energy flaring episode

The nearby elliptical galaxy M87 contains one of only two supermassive black holes whose emission surrounding the event horizon has been imaged by the Event Horizon Telescope (EHT). In 2018, more than two dozen multi-wavelength (MWL) facilities (from radio to gamma -ray energies) took part in the second M87 EHT campaign. The goal of this extensive MWL campaign was to better understand the physics of the accreting black hole M87*, the relationship between the inflow and inner jets, and the high-energy particle acceleration. Understanding the complex astrophysics is also a necessary first step towards performing further tests of general relativity. The MWL campaign took place in April 2018, overlapping with the EHT M87* observations. We present a new, contemporaneous spectral energy distribution (SED) ranging from radio to very high-energy (VHE) gamma -rays as well as details of the individual observations and light curves. We also conducted phenomenological modelling to investigate the basic source properties. We present the first VHE gamma -ray flare from M87 detected since 2010. The flux above 350 GeV more than doubled within a period of approx 36 hours. We find that the X-ray flux is enhanced by about a factor of two compared to 2017, while the radio and millimetre core fluxes are consistent between 2017 and 2018. We detect evidence for a monotonically increasing jet position angle that corresponds to variations in the bright spot of the EHT image. Our results show the value of continued MWL monitoring together with precision imaging for addressing the origins of high-energy particle acceleration. While we cannot currently pinpoint the precise location where such acceleration takes place, the new VHE gamma -ray flare already presents a challenge to simple one-zone leptonic emission model approaches, and it emphasises the need for combined image and spectral modelling.

Publication Details

Journal
Maryland Shared Open Access Repository (USMAI Consortium)
Published
2024-09-20
DOI
https://doi.org/10.13016/m2i0rx-w24d
Primary Topic
Public Administration and Political Analysis
Type
article
Field-Weighted Citation Impact
0.00

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article

Broadband multi-wavelength properties of M87 during the 2018 EHT campaign including a very high energy flaring episode

Maryland Shared Open Access Repository (USMAI Consortium)
Public Administration and Political Analysis
article

Broadband multi-wavelength properties of M87 during the 2018 EHT campaign including a very high energy flaring episode

article en

Abstract

The nearby elliptical galaxy M87 contains one of only two supermassive black holes whose emission surrounding the event horizon has been imaged by the Event Horizon Telescope (EHT). In 2018, more than two dozen multi-wavelength (MWL) facilities (from radio to gamma -ray energies) took part in the second M87 EHT campaign. The goal of this extensive MWL campaign was to better understand the physics of the accreting black hole M87*, the relationship between the inflow and inner jets, and the high-energy particle acceleration. Understanding the complex astrophysics is also a necessary first step towards performing further tests of general relativity. The MWL campaign took place in April 2018, overlapping with the EHT M87* observations. We present a new, contemporaneous spectral energy distribution (SED) ranging from radio to very high-energy (VHE) gamma -rays as well as details of the individual observations and light curves. We also conducted phenomenological modelling to investigate the basic source properties. We present the first VHE gamma -ray flare from M87 detected since 2010. The flux above 350 GeV more than doubled within a period of approx 36 hours. We find that the X-ray flux is enhanced by about a factor of two compared to 2017, while the radio and millimetre core fluxes are consistent between 2017 and 2018. We detect evidence for a monotonically increasing jet position angle that corresponds to variations in the bright spot of the EHT image. Our results show the value of continued MWL monitoring together with precision imaging for addressing the origins of high-energy particle acceleration. While we cannot currently pinpoint the precise location where such acceleration takes place, the new VHE gamma -ray flare already presents a challenge to simple one-zone leptonic emission model approaches, and it emphasises the need for combined image and spectral modelling.

Maryland Shared Open Access Repository (USMAI Consortium)
National Science Foundation, Smithsonian Institution, U.S. Department of Energy, National Aeronautics and Space Administration, John Templeton Foundation, Gordon and Betty Moore Foundation, University of Chicago, University of Arizona, National Center for Theoretical Sciences, Compute Canada, Netherlands eScience Center, Space Telescope Science Institute, Ministerio de Ciencia, Innovación y Universidades, National Radio Astronomy Observatory, Associated Universities, National Energy Research Scientific Computing Center, International Max Planck Research School for Environmental, Cellular and Molecular Microbiology, Joint Institute for Computational Fundamental Science, Flatiron Health, Government of Canada, Leverhulme Trust, European Commission, National Research Foundation, University of Pretoria, Deutsche Forschungsgemeinschaft, Ministry of Education, Culture, Sports, Science and Technology, Canada Research Chairs, Fundação de Amparo à Pesquisa do Estado de São Paulo, National Natural Science Foundation of China, Academia Sinica, Chinese Academy of Sciences, China Postdoctoral Science Foundation, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Generalitat Valenciana, Nuclear Safety and Security Commission, Korea Astronomy and Space Science Institute, National Research Foundation of Korea, Max-Planck-Gesellschaft, Vetenskapsrådet, Ministry of Education, India, China Scholarship Council, European Southern Observatory, Centre National de la Recherche Scientifique, Ministerio de Ciencia e Innovación, Shanghai Jiao Tong University, Universidad Nacional Autónoma de México, National Astronomical Observatory of Japan, Junta de Andalucía, Istituto Nazionale di Fisica Nucleare, Ministry of Science and ICT, South Korea, Fundación Bancaria Caixa d'Estalvis i Pensions de Barcelona, Instituto de Astrofísica de Andalucía, Agencia Nacional de Investigación y Desarrollo, National Science and Technology Council, Institut Périmètre de physique théorique, East Asian Core Observatories Association, Toray Science Foundation, Office of Science, National Nuclear Security Administration, Physics Division, National Center for Theoretical Sciences, Natural Sciences and Engineering Research Council of Canada, Science and Technology Facilities Council, Japan Society for the Promotion of Science, Consejo Superior de Investigaciones Científicas, Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México, National Institutes of Natural Sciences, Agencia Estatal de Investigación, National Key Research and Development Program of China, National Science Fund for Distinguished Young Scholars, Office of International Science and Engineering, High Energy Physics, Oak Ridge National Laboratory, Los Alamos National Laboratory
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