Broadband characterisation of the very intense TeV flares of the blazar 1ES 1959+650 in 2016

V. A. Acciari, S. Ansoldi, L. A. Antonelli, A. Arbet Engels, D. Baack, A. Babić, B. Banerjee, U. Barres De Almeida, J. A. Barrio, J. Becerra González, W. Bednarek, L. Bellizzi, E. Bernardini, A. Berti, J. Besenrieder, W. Bhattacharyya, C. Bigongiari, A. Biland, O. Blanch, G. BonnoliZ. Bosnjak, G. Busetto, R. Carosi, G. Ceribella, Y. Chai, S. Cikota, S. M. Colak, U. Colin, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, V. D'Elia, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, M. Delfino, J. Delgado, F. Di Pierro, E. Do Souto Espiñeira, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, M. Gaug, C. Maggio, V. Moreno, P. Munar-Adrover, C. Nigro

Research output: Contribution to journalReview articleResearchpeer-review

26 Citations (Scopus)

Abstract

1ES 1959+650 is a bright TeV high-frequency-peaked BL Lac object exhibiting interesting features like orphan TeV flares and broad emission in the high-energy regime that are difficult to interpret using conventional one-zone Synchrotron Self-Compton (SSC) scenarios. We report the results from the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) observations in 2016 along with the multi-wavelength data from the Fermi Large Area Telescope (LAT) and Swift instruments. MAGIC observed 1ES 1959+650 with different emission levels in the very-high-energy (VHE, E > 100 GeV) -ray band during 2016. In the long-term data, the X-ray spectrum becomes harder with increasing flux and a hint of a similar trend is also visible in the VHE band. An exceptionally high VHE flux reaching ∼3 times the Crab Nebula flux was measured by MAGIC on the 13 and 14 of June, and 1 July 2016 (the highest flux observed since 2002). During these flares, the high-energy peak of the spectral energy distribution (SED) lies in the VHE domain and extends up to several TeV. The spectrum in the -ray (both Fermi-LAT and VHE bands) and the X-ray bands are quite hard. On 13 June and 1 July 2016, the source showed rapid variations in the VHE flux within timescales of less than an hour. A simple one-zone SSC model can describe the data during the flares requiring moderate to large values of the Doppler factors (δ ≥ 30..60). Alternatively, the high-energy peak of the SED can be explained by a purely hadronic model attributed to proton-synchrotron radiation with jet power Ljet∼ 1046erg s-1and under high values of the magnetic field strength (∼100 G) and maximum proton energy (∼few EeV). Mixed leptohadronic models require super-Eddington values of the jet power. We conclude that it is difficult to get detectable neutrino emission from the source during the extreme VHE flaring period of 2016.

Original languageEnglish
Article numberA14
JournalAstronomy and Astrophysics
Volume638
DOIs
Publication statusPublished - 1 Jun 2020

Keywords

  • Astroparticle physics
  • BL Lacertae objects: individual: 1ES 1959+650
  • Galaxies: jets
  • Methods: observational
  • Neutrinos
  • Radiation mechanisms: non-thermal

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