Observational Evidence of an Internal Shock Collision in the Relativistic Jet of the Nearby Radio Galaxy 3C 111
Year: 2026
Type: preprint
Abstract: We report 10 epochs of 22 GHz East Asia To Italy: Nearly Global VLBI (EATING VLBI) observations of the nearby radio galaxy 3C~111 obtained from 2020 to 2023. Combined with VLBA data at 15 and 43 GHz, these observations yield a 64-epoch, multi-frequency sequence of high-resolution radio images. We used high-resolution Bayesian Stokes~I imaging and Gaussian component modeling to derive light curves and knot kinematics. We find evidence that a faster, later-emitted knot catches up with a slower, earlier knot at a deprojected distance of about 10 pc from the central engine. The knot component responsible for this interaction propagated at relativistic speed and exhibited a rise-and-decay evolution over approximately six months. The Stokes~I flux evolution supports the internal shock interpretation, while archival polarization images reveal a temporary increase in fractional linear polarization in the interaction region near the Stokes~I flux maximum. The timing of the 2021 GeV flare suggests that this earlier high-energy event is more naturally associated with activity near the core. These results provide direct evidence for an internal shock in an active galactic nucleus jet and support a hybrid picture in which internal and standing shocks coexist in relativistic jets and may play different roles in their variability.
Source: arXiv (Cornell University)
Authors: Kawamura, Kenzo, Kino, Motoki, Honma, Mareki, Hada, Kazuhiro, Tiede, Paul, Kravchenko, Evgeniya, Giroletti, Marcello, Lico, Rocco, Akiyama, Kazunori, Takamura, Mieko, D'Ammando, Filippo, Orienti, Monica, Giovannini, Gabriele, Tazaki, Fumie, Sohn, Bong Won, Buttaccio, Salvatore, Cui, Lang, Maccaferri, Giuseppe, Melis, Andrea, Melnikov, Alexey, Migoni, Carlo, Stagni, Matteo, Wajima, Kiyoaki, Sakai, Takeshi
Institutions: University of Electro-Communications, National Astronomical Observatory of Japan, Kogakuin University, Nagoya City University, Harvard University, Center for Astrophysics Harvard & Smithsonian, Istituto di Radioastronomia di Bologna, National Institute for Astrophysics, Instituto de Astrofísica de Andalucía, University of Bologna, Tokyo Electron Technology Solutions Limited (Japan), Osservatorio Astrofisico di Catania, Chinese Academy of Sciences, Xinjiang Astronomical Observatory, Osservatorio Astronomico di Cagliari, Russian Academy of Sciences, Institute of Applied Astronomy, Korea Astronomy and Space Science Institute, Korea University of Science and Technology
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, National Aeronautics and Space Administration, Gordon and Betty Moore Foundation, Daiko Foundation, Ministry of Education, Culture, Sports, Science and Technology, National Astronomical Observatory of Japan, Nagoya City University, Japan Society for the Promotion of Science
Awards: Imaging the Dynamic Atmospheres of Evolved Stars at Radio Wavelengths, G3920734589, G403890863, G5037849455, 超大規模計算と超高精度観測で解き明かすブラックホールジェットの駆動機構と多様性, G5413674638, G5507044963, G6392631596, G6643241194, G6834019471, G6925086031, Unveiling the Driving Mechanisms of AGN Jets through the Synergy of High-Resolution X-ray Spectroscopy and Millimeter-Wave Imaging, Collaborative Research: RI:Small: Use-Inspired RL for Many-Agent Contexts: Co-opetition, Partial Observability, and Dynamic Types, SII-Center: SpectrumX – An NSF Spectrum Innovation Center, The Event Horizon Telescope: Resolving Black Holes in Time and Space, G766651960, G8173126264, Understanding the formation mechanisms of supermassive black holes jets using high-resolution and high-cadence millimeter VLBI observations, Frontier Science with the Event Horizon Telescope
OpenAlex ID: W7214023950