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

164si1ES 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.nonemixedAcciari V.A.; Ansoldi S.; Antonelli L.A.; Arbet Engels A.; Baack D.; Babic A.; Banerjee B.; Barres De Almeida U.; Barrio J.A.; Becerra Gonzalez J.; Bednarek W.; Bellizzi L.; Bernardini E.; Berti A.; Besenrieder J.; Bhattacharyya W.; Bigongiari C.; Biland A.; Blanch O.; Bonnoli G.; Bosnjak Z.; Busetto G.; Carosi R.; Ceribella G.; Chai Y.; Cikota S.; Colak S.M.; Colin U.; Colombo E.; Contreras J.L.; Cortina J.; Covino S.; D'Elia V.; Da Vela P.; Dazzi F.; De Angelis A.; De Lotto B.; Delfino M.; Delgado J.; Di Pierro F.; Do Souto Espineira E.; Dominis Prester D.; Donini A.; Dorner D.; Doro M.; Elsaesser D.; Fallah Ramazani V.; Fattorini A.; Fernandez-Barral A.; Ferrara G.; Fidalgo D.; Foffano L.; Fonseca M.V.; Font L.; Fruck C.; Fukami S.; Gallozzi S.; Garcia Lopez R.J.; Garczarczyk M.; Gasparyan S.; Gaug M.; Godinovic N.; Green D.; Guberman D.; Hadasch D.; Hahn A.; Herrera J.; Hoang J.; Hrupec D.; Inada T.; Inoue S.; Ishio K.; Iwamura Y.; Jouvin L.; Kubo H.; Kushida J.; Lamastra A.; Lelas D.; Leone F.; Lindfors E.; Lombardi S.; Longo F.; Lopez M.; Lopez-Coto R.; Lopez-Oramas A.; MacHado De Oliveira Fraga B.; Maggio C.; Majumdar P.; Makariev M.; Mallamaci M.; Maneva G.; Manganaro M.; Mannheim K.; Maraschi L.; Mariotti M.; Martinez M.; Masuda S.; Mazin D.; Micanovic S.; Miceli D.; Minev M.; Miranda J.M.; Mirzoyan R.; Molina E.; Moralejo A.; Morcuende D.; Moreno V.; Moretti E.; Munar-Adrover P.; Neustroev V.; Niedzwiecki A.; Nigro C.; Nilsson K.; Ninci D.; Nishijima K.; Noda K.; Nogues L.; Nothe M.; Nozaki S.; Paiano S.; Palacio J.; Palatiello M.; Paneque D.; Paoletti R.; Paredes J.M.; Penil P.; Peresano M.; Persic M.; Prada Moroni P.G.; Prandini E.; Puljak I.; Rhode W.; Ribo M.; Rico J.; Righi C.; Rugliancich A.; Saha L.; Sahakyan N.; Saito T.; Sakurai S.; Satalecka K.; Schweizer T.; Sitarek J.; Snidaric I.; Sobczynska D.; Somero A.; Stamerra A.; Strom D.; Strzys M.; Suric T.; Takahashi M.; Tavecchio F.; Temnikov P.; Terzic T.; Teshima M.; Torres-Alba N.; Tsujimoto S.; Van Scherpenberg J.; Vanzo G.; Vazquez Acosta M.; Vovk I.; Will M.; Zaric D.; Hayashida M.Acciari, V. A.; Ansoldi, S.; Antonelli, L. A.; Arbet Engels, A.; Baack, D.; Babic, A.; Banerjee, B.; Barres De Almeida, U.; Barrio, J. A.; Becerra Gonzalez, J.; Bednarek, W.; Bellizzi, L.; Bernardini, E.; Berti, A.; Besenrieder, J.; Bhattacharyya, W.; Bigongiari, C.; Biland, A.; Blanch, O.; Bonnoli, G.; Bosnjak, Z.; Busetto, G.; Carosi, R.; Ceribella, G.; Chai, Y.; Cikota, S.; Colak, S. M.; Colin, U.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; D'Elia, V.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; Delfino, M.; Delgado, J.; Di Pierro, F.; Do Souto Espineira, E.; Dominis Prester, D.; Donini, A.; Dorner, D.; Doro, M.; Elsaesser, D.; Fallah Ramazani, V.; Fattorini, A.; Fernandez-Barral, A.; Ferrara, G.; Fidalgo, D.; Foffano, L.; Fonseca, M. V.; Font, L.; Fruck, C.; Fukami, S.; Gallozzi, S.; Garcia Lopez, R. J.; Garczarczyk, M.; Gasparyan, S.; Gaug, M.; Godinovic, N.; Green, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Herrera, J.; Hoang, J.; Hrupec, D.; Inada, T.; Inoue, S.; Ishio, K.; Iwamura, Y.; Jouvin, L.; Kubo, H.; Kushida, J.; Lamastra, A.; Lelas, D.; Leone, F.; Lindfors, E.; Lombardi, S.; Longo, F.; Lopez, M.; Lopez-Coto, R.; Lopez-Oramas, A.; MacHado De Oliveira Fraga, B.; Maggio, C.; Majumdar, P.; Makariev, M.; Mallamaci, M.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martinez, M.; Masuda, S.; Mazin, D.; Micanovic, S.; Miceli, D.; Minev, M.; Miranda, J. M.; Mirzoyan, R.; Molina, E.; Moralejo, A.; Morcuende, D.; Moreno, V.; Moretti, E.; Munar-Adrover, P.; Neustroev, V.; Niedzwiecki, A.; Nigro, C.; Nilsson, K.; Ninci, D.; Nishijima, K.; Noda, K.; Nogues, L.; Nothe, M.; Nozaki, S.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Penil, P.; Peresano, M.; Persic, M.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Rhode, W.; Ribo, M.; Rico, J.; Righi, C.; Rugliancich, A.; Saha, L.; Sahakyan, N.; Saito, T.; Sakurai, S.; Satalecka, K.; Schweizer, T.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Somero, A.; Stamerra, A.; Strom, D.; Strzys, M.; Suric, T.; Takahashi, M.; Tavecchio, F.; Temnikov, P.; Terzic, T.; Teshima, M.; Torres-Alba, N.; Tsujimoto, S.; Van Scherpenberg, J.; Vanzo, G.; Vazquez Acosta, M.; Vovk, I.; Will, M.; Zaric, D.; Hayashida, M