RT Journal Article T1 The Blazar TXS 0506+056 Associated with a High-energy Neutrino: Insights into Extragalactic Jets and Cosmic-Ray Acceleration A1 Barrio Uña, Juan Abel A1 Contreras González, José Luis A1 Domínguez Díaz, Alberto A1 Carreto Fidalgo, David Friedrich A1 Fonseca González, María Victoria A1 Hoang, Kim Dinh A1 López Moya, Marcos A1 Nievas Rosillo, Mireia A1 Peñil Del Campo, Pablo A1 Saha, Lab AB A neutrino with energy similar to 290 TeV, IceCube-170922A, was detected in coincidence with the BL Lac object TXS. 0506+056 during enhanced gamma-ray activity, with chance coincidence being rejected at similar to 3 sigma level. We monitored the object in the very-high-energy (VHE) band with the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes for similar to 41 hr from 1.3 to 40.4 days after the neutrino detection. Day-timescale variability is clearly resolved. We interpret the quasi-simultaneous neutrino and broadband electromagnetic observations with a novel one-zone lepto-hadronic model, based on interactions of electrons and protons co-accelerated in the jet with external photons originating from a slow-moving plasma sheath surrounding the faster jet spine. We can reproduce the multiwavelength spectra of TXS 0506+056 with neutrino rate and energy compatible with IceCube-170922A, and with plausible values for the jet power of similar to 10(45) - 4 x 10(46) erg s(-1). The steep spectrum observed by MAGIC is concordant with internal gamma gamma absorption above similar to 100 GeV entailed by photohadronic production of a similar to 290 TeV neutrino, corroborating a genuine connection between the multi-messenger signals. In contrast to previous predictions of predominantly hadronic emission from neutrino sources, the gamma-rays can be mostly ascribed to inverse Compton upscattering of external photons by accelerated electrons. The X-ray and VHE bands provide crucial constraints on the emission from both accelerated electrons and protons. We infer that the maximum energy of protons in the jet comoving frame can be in the range similar to 10(14) - 10(18) eV. PB IOP Publishing Ltd SN 2041-8205 YR 2018 FD 2018-08-10 LK https://hdl.handle.net/20.500.14352/13082 UL https://hdl.handle.net/20.500.14352/13082 LA eng NO © 2018. The American Astronomical Society. Artículo firmado por 149 autores. We would like to thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2015-69818-P, FPA2012-36668, FPA2015-68378-P, FPA2015-69210-C6-2-R, FPA2015-69210-C6-4-R, FPA2015-69210-C6-6-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2015-71662-C2-2-P, CSD2009-00064), and the Japanese JSPS and MEXT is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia "Severo Ochoa" SEV-2012-0234 and SEV-2015-0548, and Unidad de Excelencia "María de Maeztu" MDM-2014-0369, by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq and FAPERJ. Part of this work is based on archival data, software or on-line services provided by the Space Science Data Center-ASI. NO Ministerio de Economía y Competitividad (MINECO)/FEDER NO Centro de Excelencia "Severo Ochoa" NO Unidad de Excelencia "María de Maeztu" NO German BMBF NO MPG NO Italian INFN NO INAF NO Swiss National Fund SNF NO Japanese JSPS NO MEXT NO Croatian Science Foundation (HrZZ) Project NO University of Rijeka Project NO DFG Collaborative Research Centers NO Polish National Research Centre NO Brazilian MCTIC NO Brazilian CNPq NO Brazilian FAPERJ DS Docta Complutense RD 18 abr 2025