Very high energy observations of the Seyfert galaxy NGC 4151 with MAGIC

Indication of another gamma-ray obscured candidate neutrino source

¹ Japanese MAGIC Group: Department of Physics, Tokai University, Hiratsuka, 259-1292 Kanagawa, Japan
² Japanese MAGIC Group: Institute for Cosmic Ray Research (ICRR), The University of Tokyo, Kashiwa, 277-8582 Chiba, Japan
³ ETH Zürich, CH-8093 Zürich, Switzerland
⁴ Università di Siena and INFN Pisa, I-53100 Siena, Italy
⁵ Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology (BIST), E-08193 Bellaterra, (Barcelona), Spain
⁶ Universitat de Barcelona, ICCUB, IEEC-UB, E-08028 Barcelona, Spain
⁷ Instituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
⁸ National Institute for Astrophysics (INAF), I-00136 Rome, Italy
⁹ Università di Udine and INFN Trieste, I-33100 Udine, Italy
¹⁰ Max-Planck-Institut für Physik, D-85748 Garching, Germany
¹¹ Università di Padova and INFN, I-35131 Padova, Italy
¹² Instituto de Astrofísica de Canarias and Dpto. de Astrofísica, Universidad de La Laguna, E-38200 La Laguna, Tenerife, Spain
¹³ Croatian MAGIC Group: University of Zagreb, Faculty of Electrical Engineering and Computing (FER), 10000 Zagreb, Croatia
¹⁴ Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, Kolkata, 700064 West Bengal, India
¹⁵ Centro Brasileiro de Pesquisas Físicas (CBPF), 22290-180 URCA, Rio de Janeiro (RJ), Brazil
¹⁶ IPARCOS Institute and EMFTEL Department, Universidad Complutense de Madrid, E-28040 Madrid, Spain
¹⁷ University of Lodz, Faculty of Physics and Applied Informatics, Department of Astrophysics, 90-236 Lodz, Poland
¹⁸ Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, E-28040 Madrid, Spain
¹⁹ Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
²⁰ Università di Pisa and INFN Pisa, I-56126 Pisa, Italy
²¹ INFN MAGIC Group: INFN Sezione di Bari and Dipartimento Interateneo di Fisica dell’Università e del Politecnico di Bari, I-70125 Bari, Italy
²² Department for Physics and Technology, University of Bergen, Bergen, Norway
²³ INFN MAGIC Group: INFN Sezione di Torino and Università degli Studi di Torino, I-10125 Torino, Italy
²⁴ Croatian MAGIC Group: University of Rijeka, Faculty of Physics, 51000 Rijeka, Croatia
²⁵ Universität Würzburg, D-97074 Würzburg, Germany
²⁶ Technische Universität Dortmund, D-44221 Dortmund, Germany
²⁷ Japanese MAGIC Group: Physics Program, Graduate School of Advanced Science and Engineering, Hiroshima University, 739-8526 Hiroshima, Japan
²⁸ Deutsches Elektronen-Synchrotron (DESY), D-15738 Zeuthen, Germany
²⁹ Armenian MAGIC Group: ICRANet-Armenia, 0019 Yerevan, Armenia
³⁰ Croatian MAGIC Group: University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture (FESB), 21000 Split, Croatia
³¹ Croatian MAGIC Group: Josip Juraj Strossmayer University of Osijek, Department of Physics, 31000 Osijek, Croatia
³² Finnish MAGIC Group: Finnish Centre for Astronomy with ESO, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
³³ University of Geneva, Chemin d’Ecogia 16, CH-1290 Versoix, Switzerland
³⁴ Inst. for Nucl. Research and Nucl. Energy, Bulgarian Academy of Sciences, BG-1784 Sofia, Bulgaria
³⁵ INFN MAGIC Group: INFN Sezione di Catania and Dipartimento di Fisica e Astronomia, University of Catania, I-95123 Catania, Italy
³⁶ Japanese MAGIC Group: Department of Physics, Yamagata University, Yamagata, 990-8560 Japan
³⁷ Finnish MAGIC Group: Space Physics and Astronomy Research Unit, University of Oulu, FI-90014 Oulu, Finland
³⁸ Japanese MAGIC Group: Chiba University, ICEHAP, 263-8522 Chiba, Japan
³⁹ Japanese MAGIC Group: Institute for Space-Earth Environmental Research and Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University, 464-6801 Nagoya, Japan
⁴⁰ Japanese MAGIC Group: Department of Physics, Kyoto University, 606-8502 Kyoto, Japan
⁴¹ INFN MAGIC Group: INFN Roma Tor Vergata, I-00133 Roma, Italy
⁴² Japanese MAGIC Group: Department of Physics, Konan University, Kobe, Hyogo, 658-8501 Japan
⁴³ also at International Center for Relativistic Astrophysics (ICRA), Rome, Italy
⁴⁴ also at Como Lake centre for AstroPhysics (CLAP), DiSAT, Università dell’Insubria, Via Valleggio 11, 22100 Como, Italy
⁴⁵ also at Port d’Informació Científica (PIC), E-08193 Bellaterra, (Barcelona), Spain
⁴⁶ now at Université Paris Cité, CNRS, Astroparticule et Cosmologie, F-75013 Paris, France
⁴⁷ also at Dipartimento di Fisica, Università di Trieste, I-34127 Trieste, Italy
⁴⁸ Max-Planck-Institut für Physik, D-85748 Garching, Germany
⁴⁹ also at Università Tor Vergata, Dipartimento di Fisica, Via della Ricerca Scientifica 1, I-00133 Rome, Italy
⁵⁰ also at INAF Padova, Padova, Italy
⁵¹ Japanese MAGIC Group: Institute for Cosmic Ray Research (ICRR), The University of Tokyo, Kashiwa, 277-8582 Chiba, Japan
⁵² ETH Zürich, CH-8093 Zürich, Switzerland
⁵³ INAF – Astrophysical Observatory of Arcetri, Largo E. Fermi 5, 50125 Florence, Italy
⁵⁴ Université Paris Cité, CNRS, Astroparticule et Cosmologie, 10 Rue Alice Domon et Léonie Duquet, 75013 Paris, France

^⋆ Corresponding authors: contact.magic@mpp.mpg.de

Received: 24 March 2025
Accepted: 16 July 2025

Abstract

Seyfert galaxies are emerging as a promising source class of high-energy neutrinos. The Seyfert galaxies NGC 4151 and NGC 1068 have respectively come up as the most promising counterparts of a 3σ and of a 4.2σ neutrino excesses detected by IceCube in the TeV energy range. Constraining the very high energy (VHE) emission associated with the neutrino signal is crucial to unveiling the mechanism and site of neutrino production. In this work, we present the first results of the VHE observations (∼29 hours) of NGC 4151 with the MAGIC telescopes. We detected no gamma-ray excess in the direction of NGC 4151, and we derived constraining upper limits on the VHE gamma-ray flux. The integral flux upper limit (at the 95% confidence level) above 200 GeV is f = 2.3 × 10⁻¹² cm⁻² s⁻¹. Comparison of the MAGIC and IceCube measurements suggests the presence of a gamma-ray obscured accelerator, and it allowed us to constrain the gamma-ray optical depth and the size of the neutrino production site.