M87's Powerful Jet Unleashes Rare Gamma-ray Outburst
An international team of researchers including a number of MPIfR scientists has just released the results of a large campaign on supermassive black hole in the centre of M87 of Event Horizon Telescope and Global mm-VLBI Array observations in 2018, involving over twenty-five ground-based and space-based telescopes including EHT and GMVA. They show a spectacular flare at multiple wavelengths from the powerful relativistic jet emanating from the very centre of that galaxy. This study reveals the first observation in over a decade of a high-energy gamma-ray flare.
Millimetre VLBI facilities, represented by two arrays, the Event Horizon Telescope (EHT) and the Global mm-VLBI Array (GMVA), the latter coordinated by the Max Planck Institute for Radio Astronomy (MPIfR), are global networks of radio telescopes regularly interconnected to observe the innermost structures of galactic nuclei and to image the shadows of supermassive black holes.
“We were fortunate to detect a gamma-ray flare from M87 during the EHT's multi-wavelength campaign—the first such event in over a decade,” says Giacomo Principe, publication coordinator and researcher at the University of Trieste. “This rare event allowed us to pinpoint the region producing the gamma-ray emission. Recent and upcoming observations with a more sensitive EHT array will provide critical insights into the physics around M87’s supermassive black hole, exploring the disk-jet connection and the origins of gamma-ray photons.”
Messier 87, also known as Virgo A or NGC 4486, is the brightest object in the Virgo cluster of galaxies, the largest gravitationally bound type of structure in the universe. The relativistic jet examined by the researchers is surprising in its extent, reaching sizes that exceed the black hole’s event horizon by tens of millions of times (7 orders of magnitude) - akin to the difference between the size of a bacterium and the largest known blue whale.
The energetic flare, which lasted approximately three days and suggests an emission region of less than three light-days in size (~170 AU, where 1 Astronomical Unit is the distance from the Sun to Earth), revealed a bright burst of high-energy emission—well above the energies typically detected by radio telescopes from the black hole region.
“High-cadence very-high-energy gamma-ray observations during both a steady state and a rare short-term flare—the first in over a decade—were achieved through the collaboration of three imaging high-energy telescope arrays”, explains Alexander Hahn from the Max Planck Institute for Physics, a co-author of the study. “Combined with simultaneous multi-wavelength data at lower energies, these observations offer crucial insights into the extreme processes powering these cosmic events.”
During the campaign, the LAT instrument aboard the Fermi space observatory detected an increase in high-energy gamma-ray flux with energies up to billions of times greater than visible light. The satellites Chandra and NuSTAR then collected high-quality data in the X-ray band. Radio observations with VLBI arrays such as the GMVA, the Very Long Baseline Array (VLBA) and the East Asian VLBI Network (EAVN) show a relativistic jet and an apparent annual change in the jet's position angle within a few milliarcseconds of arc from the galaxy's core.
“The radio imaging provides a unique perspective, allowing astronomers to track the structural and temporal evolution of the jet at unprecedented angular resolutions”, says Thomas Krichbaum of the MPIfR. “In this campaign, radio data not only constrained the jet geometry but also served as a vital reference for correlating the gamma-ray emission with the relativistic jet dynamics.”
Observations show changes in the position of the ring's asymmetry (the black hole's event horizon) and the jet's position. This suggests a physical link between these structures on very different scales. “The first image from the 2017 observational campaign showed that the ring’s emission was uneven, with brighter areas indicating asymmetries. Subsequent 2018 observations confirmed these findings, showing that the position angle of the asymmetry had shifted”, says Daryl Haggard, professor at McGill University and co-coordinator of the EHT multi-wavelength working group.
This is a prime example of how radio observations of the most violent objects in the Universe are complemented by high-energy telescopes like those used in this major campaign. The MPIfR participates in this effort with observations performed with the GMVA and the EHT. These radio data were, among other, postprocessed at the MPIfR correlator facility in Bonn. MPIfR radio telescopes participating in these arrays are the 100-m telescope in Effelsberg and the 12-m APEX telescope in Chile. The 30-m IRAM telescope in Pico Veleta, Spain, recently complemented by the IRAM/NOEMA telescope array in the French Alps, added substantial sensitivity to these observations.
“This observing campaign produced the first image ever showing both the black hole shadow and the jet in M87, presented in April 2023, and now we see that new, exciting results are coming from the coordinated observations carried out around the second global EHT campaign”, recalls Eduardo Ros, astronomer at the MPIfR and European scheduler of the GMVA.
J. Anton Zensus, director at the MPIfR and founding chair of the EHT collaboration, concludes: "The contribution of cutting-edge technology in radio astronomy, in coordination with different facilities on Earth and beyond, shows here in a special way how multi-band studies of sources such as Messier 87 pave the way for stimulating future research and potential breakthroughs in understanding the Universe".
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Additional Information
The EHT collaboration involves more than 400 researchers from Africa, Asia, Europe, North and South America, with around 270 participating in this paper. The international collaboration aims to capture the most detailed images of black holes using a virtual Earth-sized telescope. Supported by considerable international efforts, the EHT links existing telescopes using novel techniques to create a fundamentally new instrument with the highest angular resolving power that has yet been achieved.
The EHT consortium consists of 13 stakeholder institutes; the Academia Sinica Institute of Astronomy and Astrophysics, the University of Arizona, the Center for Astrophysics | Harvard & Smithsonian, the University of Chicago, the East Asian Observatory, the Goethe University Frankfurt, the Institut de Radioastronomie Millimétrique, the Large Millimeter Telescope, the Max Planck Institute for Radio Astronomy, the MIT Haystack Observatory, the National Astronomical Observatory of Japan, the Perimeter Institute for Theoretical Physics, and the Radboud University.
The EHT array operating at 1.3 mm wavelength included ALMA, APEX, the IRAM 30-meter Telescope, the IRAM NOEMA Observatory, the James Clerk Maxwell Telescope (JCMT), the Large Millimeter Telescope (LMT), the Submillimeter Array (SMA), the Submillimeter Telescope (SMT), the South Pole Telescope (SPT), the Kitt Peak Telescope (KP), and the Greenland Telescope (GLT). The GMVA, observing at adjacent days at a wavelength of 3.5 mm included the 100-m radio telescope in Effelsberg. GMVA and EHT data were post-processed at the MPIfR correlator facility. The EHT data were also correlated at the MIT/Haystack Observatory in Westford, MA, USA. Further analysis was performed in the framework of the global EHT collaboration.
The second EHT and multi-wavelength campaign in 2018 leveraged more than two dozen high-profile observational facilities, including NASA’s Fermi-LAT, the Hubble Space Telescope, NuSTAR, Chandra, and Swift telescopes, together with the world’s three largest Imaging Atmospheric Cherenkov Telescope arrays (H.E.S.S., MAGIC and VERITAS). These observatories are sensitive to X-ray photons as well as high-energy and very-high-energy gamma-rays, respectively.
Researchers affiliated with the Max Planck Institut für Radioastronomie, listed as co-authors in the published research, are: Jae-Young Kim, Ru-sen Lu, and also Walter Alef, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, Silke Britzen, Gregory Desvignes, Sergio A. Dzib, Ralph Eatough, Christian M. Fromm, Michael Janssen, Joana A. Kramer, Michael Kramer, Thomas P. Krichbaum, Mikhail Lisakov, Jun Liu, Kuo Liu, Andrei P. Lobanov, Nicholas R. MacDonald, Nicola Marchili, Karl M. Menten, Cornelia Müller, Hendrik Müller, Gisela Ortiz-Leon, Georgios Filippos Paraschos, Felix Poetzl, Eduardo Ros, Helge Rottmann, Alan L. Roy, Tuomas Savolainen, Lijing Shao, Pablo Torne, Efthalia Traianou, Jan Wagner, Robert Wharton, Maciek Wielgus, Gunther Witzel, J. Anton Zensus, and Guang-Yao Zhao.
Wissenschaftlicher Ansprechpartner:
Dr. Thomas P. Krichbaum
Max Planck Institute for Radio Astronomy, Bonn
Fon: +49 228 525-295
E-mail: tkrichbaum@mpifr-bonn.mpg.de
Prof. Dr. J. Anton Zensus
Director and Head of Radio Astronomy/VLBI Research Dept.
Max Planck Institute for Radio Astronomy, Bonn
Fon: +49 228 525-298 (secretary)
E-mail: azensus@mpifr-bonn.mpg.de
Prof. Dr. Eduardo Ros
Max Planck Institute for Radio Astronomy, Bonn
Fon: +49 228 525-125
ros@mpifr-bonn.mpg.de
Originalpublikation:
"Broadband Multi-wavelength Properties of M87 during the 2018 EHT Campaign including a Very High Energy Flaring Episode", by The Event Horizon Telescope- Multi-wavelength science working group, The Event Horizon Telescope Collaboration, The Fermi Large Area Telescope Collaboration, H.E.S.S. Collaboration, MAGIC Collaboration, VERITAS Collaboration, and EAVN Collaboration. In: A&A, 692, A140 (2024). DOI: 10.1051/0004-6361/202450497
https://www.aanda.org/articles/aa/pdf/2024/12/aa50497-24.pdf
Preprint: https://arxiv.org/abs/2404.17623
Weitere Informationen:
https://www.mpifr-bonn.mpg.de/pressreleases/2024/12
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