MAGIC very large zenith angle observations of the Crab Nebula up to 100 TeV

¹ Instituto de Astrofísica de Canarias, 38200 La Laguna, and Universidad de La Laguna, Departamento de Astrofísica, 38206 La Laguna, Tenerife, Spain
² Università di Udine, INFN Trieste, 33100 Udine, Italy
³ National Institute for Astrophysics (INAF), 00136 Rome, Italy
⁴ ETH Zurich, CH-8093 Zurich, Switzerland
⁵ Technische Universität Dortmund, 44221 Dortmund, Germany
⁶ Croatian Consortium: University of Rijeka, Department of Physics, 51000 Rijeka; University of Split – FESB, 21000 Split; University of Zagreb – FER, 10000 Zagreb; University of Osijek, 31000 Osijek; Rudjer Boskovic Institute, 10000 Zagreb, Croatia
⁷ Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhannagar, Salt Lake, Sector-1, Kolkata 700064, India
⁸ Centro Brasileiro de Pesquisas Físicas (CBPF), 22290-180 URCA, Rio de Janeiro (RJ), Brasil
⁹ IPARCOS Institute and EMFTEL Department, Universidad Complutense de Madrid, 28040 Madrid, Spain
¹⁰ University of Łódź, Department of Astrophysics, 90236 Łódź, Poland
¹¹ Università di Siena and INFN Pisa, 53100 Siena, Italy
¹² Deutsches Elektronen-Synchrotron (DESY), 15738 Zeuthen, Germany
¹³ Istituto Nazionale Fisica Nucleare (INFN), 00044 Frascati (Roma) Italy
¹⁴ Max-Planck-Institut für Physik, 80805 München, Germany
¹⁵ Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology (BIST), 08193 Bellaterra (Barcelona), Spain
¹⁶ Università di Padova and INFN, 35131 Padova, Italy
¹⁷ Università di Pisa, and INFN Pisa, 56126 Pisa, Italy
¹⁸ ICRANet-Armenia at NAS RA, 0019 Yerevan, Armenia
¹⁹ Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, 28040 Madrid, Spain
²⁰ Universität Würzburg, 97074 Würzburg, Germany
²¹ Finnish MAGIC Consortium: Finnish Centre of Astronomy with ESO (FINCA), University of Turku, 20014 Turku, Finland; Astronomy Research Unit, University of Oulu, 90014 Oulu, Finland
²² Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
²³ Japanese MAGIC Consortium: ICRR, The University of Tokyo, 277-8582 Chiba, Japan; Department of Physics, Kyoto University, 606-8502 Kyoto, Japan; Tokai University, 259-1292 Kanagawa, Japan; RIKEN, 351-0198 Saitama, Japan
²⁴ Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
²⁵ Universitat de Barcelona, ICCUB, IEEC-UB, 08028 Barcelona, Spain
²⁶ also at Port d’Informació Científica (PIC) E-08193 Bellaterra (Barcelona) Spain
²⁷ Dipartimento di Fisica, Università di Trieste, 34127 Trieste, Italy
²⁸ INAF-Trieste and Department of Physics & Astronomy, University of Bologna, Bologna, Italy

Received: 11 October 2019
Accepted: 2 January 2020

Abstract

Aims. We measure the Crab Nebula γ-ray spectral energy distribution in the ~100 TeV energy domain and test the validity of existing leptonic emission models at these high energies.

Methods. We used the novel very large zenith angle observations with the MAGIC telescope system to increase the collection area above 10 TeV. We also developed an auxiliary procedure of monitoring atmospheric transmission in order to assure proper calibration of the accumulated data. This employs recording optical images of the stellar field next to the source position, which provides a better than 10% accuracy for the transmission measurements.

Results. We demonstrate that MAGIC very large zenith angle observations yield a collection area larger than a square kilometer. In only ~ 56 h of observations, we detect the γ-ray emission from the Crab Nebula up to 100 TeV, thus providing the highest energy measurement of this source to date with Imaging Atmospheric Cherenkov Telescopes. Comparing accumulated and archival MAGIC and Fermi/LAT data with some of the existing emission models, we find that none of them provides an accurate description of the 1 GeV to 100 TeV γ-ray signal.