Time-dependent modelling of short-term variability in the TeV-blazar VER J0521+211 during the major flare in 2020

The BL Lacertae object VER J0521+211 underwent a notable flaring episode in February 2020. A short-term monitoring campaign, led by the MAGIC (Major Atmospheric Gamma Imaging Cherenkov) collaboration, covering a wide energy range from radio to very high-energy (VHE, 100 GeV < E < 100 TeV) gamma rays was organised to study its evolution. These observations resulted in a consistent detection of the source over six consecutive nights in the VHE gamma-ray domain. Combining these nightly observations with an extensive set of multi-wavelength data made modelling of the blazar’s spectral energy distribution (SED) possible during the flare. This modelling was performed with a focus on two plausible emission mechanisms: (i) a leptonic two-zone synchrotron-self-Compton scenario, and (ii) a lepto-hadronic one-zone scenario. Both models effectively replicated the observed SED from radio to the VHE gamma-ray band. Furthermore, by introducing a set of evolving parameters, both models were successful in reproducing the evolution of the fluxes measured in different bands throughout the observing campaign. Notably, the lepto-hadronic model predicts enhanced photon and neutrino fluxes at ultra-high energies ( E > 100 TeV). While the photon component, generated via decay of neutral pions, is not directly observable as it is subject to intense pair production (and therefore extinction) through interactions with the cosmic microwave background photons, neutrino detectors (e.g. IceCube) can probe the predicted neutrino component. Finally, the analysis of the gamma-ray spectra, observed by MAGIC and the Fermi -LAT telescopes, yielded a conservative 95% confidence upper limit of z ≤ 0.244 for the redshift of this blazar.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2025-01-09
DOI
https://doi.org/10.1051/0004-6361/202451378
Primary Topic
Astrophysics and Cosmic Phenomena
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article
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article

Time-dependent modelling of short-term variability in the TeV-blazar VER J0521+211 during the major flare in 2020

Patrick Günther, J. Sitarek, F. Leone, D. Sobczyńska et al.
Astronomy and Astrophysics
Astrophysics and Cosmic Phenomena
article

Time-dependent modelling of short-term variability in the TeV-blazar VER J0521+211 during the major flare in 2020

Patrick Günther, J. Sitarek, F. Leone, D. Sobczyńska, K. Schmidt, K. Mannheim, F. Schmuckermaier, A. Biland, R. Takeishi, T. Terzić, R. Bachev, T. Aniello, T. Njoh Ekoume, M. Artero, S. Mender, E. Molina, Xavier Rodrigues, Francesco Gabriele Saturni, Alvaro Mas-Aguilar, C. Bigongiari, Juliane van Scherpenberg, P. Temnikov, D. Dorner, J.L Schubert, M. Delfino, M. Mariotti, C. Delgado Mendez, Jarred Gershon Green, L. Font, Daniel Morcuende, S. Paiano, J. Abhir, Laura Eisenberger, F. Di Pierro, D. Kerszberg, Ioannis Liodakis, T. Miener, J. Baxter, U. Barres de Almeida, Pouya M. Kouch, E. Bernardini, M. Tornikoski, P. Majumdar, F. Podobnik, Dominik Baack, R. Paoletti, M. Gaug, D. Cerasole, R. Grau, J. A. Barrio, R. Walter, Stefan Fröse, A. Bautista, A. De Angelis, J. Otero-Santos, I. Batković, F. Wierda, G. Maneva, J. Jormanainen, E. Do Souto Espiñeira, G. D'Amico, W. Max-Moerbeck, M. Carretero-Castrillo, I. Vovk, S. Fukami, A. Fattorini, M. Ribó, C. Vigorito, T. Yamamoto, T. Kayanoki, N. Sahakyan, E. Prandini, V. Sliusar, J. M. Paredes, Antonio Tutone, V. A. Acciari, G. Verna, A. Moralejo, S. Kiehlmann, C. Arcaro, A. Berti, M. Nievas Rosillo, J. Kushida, Martin Will, V. Neustroev, Y. Chai, C. Nanci, M. Garczarczyk, J. Delgado, Anastasiia Omeliukh, Miguel Molero Gonzalez, A. Lorini, C. Wunderlich, L. Fariña, A. Babić, G. Bonnoli, L. Foffano, A. Stamerra, H. A. Mondal, V. Fallah Ramazani, Miguel J. A. Láinez, S. Lombardi, Raniere de Menezes, J. Escudero, F. Dazzi, Gabriella Silvestri, S. Menchiari, J. Cortina, T. Hassan, W. Rhode, S. Covino, Arnau Aguasca-Cabot, T. Hovatta, Gert Werner Kluge, D. Elsäesser, S. Ansoldi, Y. Fukazawa, S. Gasparyan, S. Loporchio, W. Bednarek, P. Gliwny, G. Pirola, M. Manganaro, J. G. Giesbrecht Paiva, E. Lindfors, J. Rico, A. Sciaccaluga, A. Cifuentes, L. Heckmann, D. Hrupec, V. Vitale, Irene Jiménez Martínez, J. M. Miranda, A. Okumura, E. Lyard, S. Truzzi, M. Persic, M. Teshima, A. Donini, Chiara Righi, K. Noda, C. Nigro, R. Carosi, M. Pihet, M. Peresano, L. A. Antonelli, E. Colombo, W. Zheng, R. Imazawa, J. Bernete, E. Bronzini, A. Campoy-Ordaz, T. Gradetzke, S. Kankkunen, J. Becerra González, Y. Suda, Hiroyasu Tajima, F. Longo, Marcos López, S. Nozaki, A.J. Castro-Tirado, N. Giglietto, R. López-Coto, K. Nilsson, M. Doro, R. J. Garcı́a López, A. Abhishek, Y. Kobayashi, A. Lamastra, G. Ceribella, R. Di Tria, K. Terauchi, J. Herrera Llorente, T. Nakamori, P. Da Vela, D Green, T. Saito, A. Hahn, Ž. Bošnjak, J. Besenrieder, M. Vazquez Acosta, J. Strišković, R. López-Coto, D. Paneque, A. Lähteenmäki, H. Kubo, A. Carosi, B. De Lotto, S. Ventura, V. D’Elia, K. Asano, G. Principe, A. Spolon, D. Strom, F. Giordano, Y. Ohtani, I. Agudo, I. Burelli, L. Di Venere, S. Abe, A. Arbet Engels, S. Ubach, R. Mirzoyan, S. Mangano, D. Mazin, I. Viale, D. Miceli, L. Nickel, D. Hadasch, P.G. Prada Moroni, T. Schweizer, K. Ishio, M. Takahashi, O. Blanch, B. Machado de Oliveira Fraga, M. Makariev, K. Nishijima, M. Strzys, M. Martínez-Chicharro, J.L. Contreras, T. Pursimo, F. Wersig, L. Nikolić
article en

Abstract

The BL Lacertae object VER J0521+211 underwent a notable flaring episode in February 2020. A short-term monitoring campaign, led by the MAGIC (Major Atmospheric Gamma Imaging Cherenkov) collaboration, covering a wide energy range from radio to very high-energy (VHE, 100 GeV < E < 100 TeV) gamma rays was organised to study its evolution. These observations resulted in a consistent detection of the source over six consecutive nights in the VHE gamma-ray domain. Combining these nightly observations with an extensive set of multi-wavelength data made modelling of the blazar’s spectral energy distribution (SED) possible during the flare. This modelling was performed with a focus on two plausible emission mechanisms: (i) a leptonic two-zone synchrotron-self-Compton scenario, and (ii) a lepto-hadronic one-zone scenario. Both models effectively replicated the observed SED from radio to the VHE gamma-ray band. Furthermore, by introducing a set of evolving parameters, both models were successful in reproducing the evolution of the fluxes measured in different bands throughout the observing campaign. Notably, the lepto-hadronic model predicts enhanced photon and neutrino fluxes at ultra-high energies ( E > 100 TeV). While the photon component, generated via decay of neutral pions, is not directly observable as it is subject to intense pair production (and therefore extinction) through interactions with the cosmic microwave background photons, neutrino detectors (e.g. IceCube) can probe the predicted neutrino component. Finally, the analysis of the gamma-ray spectra, observed by MAGIC and the Fermi -LAT telescopes, yielded a conservative 95% confidence upper limit of z ≤ 0.244 for the redshift of this blazar.

Astronomy and AstrophysicsVol. 694
National Science Foundation, National Aeronautics and Space Administration, California Institute of Technology, Alfred Kordelinin Säätiö, Ministerio de Ciencia, Innovación y Universidades, Centres de Recerca de Catalunya, European Commission, Deutscher Akademischer Austauschdienst, Deutsche Forschungsgemeinschaft, Ministry of Education, Culture, Sports, Science and Technology, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Bundesministerium für Bildung und Forschung, Aalto-Yliopisto, Generalitat de Catalunya, Bulgarian National Science Fund, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Nuclear Safety and Security Commission, Max-Planck-Gesellschaft, Hrvatska Zaklada za Znanost, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Ministério da Ciência, Tecnologia, Inovações e Comunicações, Instituto de Astrofísica de Canarias, Japan Society for the Promotion of Science, European Regional Development Fund, Agencia Estatal de Investigación, Institute for Cosmic Ray Research, University of Tokyo
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