Multimessenger flare in the quasar PKS 0446+11
Year: 2026
Type: article
Abstract: Context. The physical mechanisms driving neutrino and electromagnetic flares in blazars remain poorly understood. Aims. We investigate a prominent multimessenger flare in the quasar PKS 0446+11 to identify the processes responsible for its high-energy emission. Methods. We analyzed the IceCube-240105A high-energy neutrino event together with contemporaneous observations in the gamma-ray, X-ray, optical, and radio bands. We modeled the on- and off-flare spectral energy distributions (SEDs) within a single-zone leptohadronic framework. Multi-epoch VLBA observations from the MOJAVE program provide parsec-scale polarization data that complement the multiwavelength light curves. Results. No significant time delay was detected between the neutrino arrival and the flares in different energy bands. This is consistent with an extremely small jet viewing angle below 1 deg, inferred from the parsec-scale polarization structure. The flare can be reproduced by the injection of a proton population and an increase in the Doppler factor from 18 to 24. We also detected an approximately 90 deg rotation of the EVPA in the parsec-scale core during the initial phase of the flare, indicating the emergence of a shock formed by the change in the bulk plasma speed. Conclusions. Our comprehensive multimessenger analysis demonstrates that the extreme beaming and subdegree viewing angle of this distant blazar can account for the observed neutrino and electromagnetic activity. These findings strengthen the case for blazars as efficient accelerators of hadrons and significant contributors to the observed high-energy neutrino flux.
Source: Astronomy and Astrophysics
Institutions: Max Planck Institute for Radio Astronomy, University of Michigan, Russian Academy of Sciences, Special Astrophysical Observatory, Consejo Superior de Investigaciones Científicas, Instituto de Astrofísica de Andalucía, Denison University, Institute for Nuclear Research, Institute for Nuclear Research, P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Purdue University West Lafayette, University of Concepción, Harvard University, Moscow Institute of Physics and Technology, Crimean Astrophysical Observatory, California Institute of Technology, Lomonosov Moscow State University
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Funders: National Science Foundation, National Aeronautics and Space Administration, John Templeton Foundation, Gordon and Betty Moore Foundation, California Institute of Technology, European Commission, Ministry of Science and Higher Education of the Russian Federation, Smithsonian Astrophysical Observatory, Science Mission Directorate, Russian Academy of Sciences
Awards: A COMPREHENSIVE DUAL HEMISPHERE NEO SURVEY., Exploring & Exploiting the Dynamic Optical Sky, G2908002831, ZWICKY TRANSIENT FACILITY, The Black Hole Initiative, G4583304758, The Black Hole Initiative: Towards a Center for Interdisciplinary Research, G6444257319, G7979606978, Black Hole Initiative Phase 3
OpenAlex ID: W4416184669