Monthly 43 GHz VLBA Polarimetric Monitoring of 3C120 over 16 Epochs: Evidence for Trailing Shocks in a Relativistic Jet

Abstract

We present a 16-month sequence of monthly polarimetric 43 GHz VLBA images of the radio galaxy 3C 120. The images probe the inner regions of the radio jet of this relatively nearby superluminal radio galaxy at a linear resolution of 0.07 $h_{65}^{-1}$ pc ($H_o=65h_{65}$ km s${}^{-1}$ Mpc${}^{-1}$). We follow the motion of a number of features with apparent velocities between 4.01$\pm$0.08 and $5.82\pm 0.13h_{65}^{-1}c$. A new superluminal knot, moving at $4.29\pm 0.16h_{65}^{-1}c$, is observed to be ejected from the core at a time coincident with the largest flare ever observed for this source at millimeter wavelengths. Changes in the position angle of this component, as well as a progressive rotation of its magnetic polarization vector, suggest the presence of a twisted (resembling a helix in projection) configuration of the underlying jet magnetic field and jet geometry. We identify several knots that appear in the wake of the new superluminal component, moving at proper motions $\sim 4$ times slower than any of the other moving knots observed in 3C 120. These features have properties similar to those of the ``trailing'' shocks seen in relativistic, time-dependent, hydrodynamical and emission simulations of compact jets. Such trailing compressions are triggered by pinch-mode jet-body instabilities caused by the propagation of a strong perturbation, which we associate with the new strong superluminal component.

4 pages, 5 figures, accepted for publication in Astrophysical Journal Letters

References in corpus (2)

• Jet stability and the generation of superluminal and stationary components
• The Structure and Motions of the 3C~120 Radio Jet on Scales of 0.6 to 300 Parsecs

Cited by in corpus (62)

• Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Jet Kinematics from Bimonthly Monitoring with the Very Long Baseline Array
• Relativistic Beaming and the Intrinsic Properties of Extragalactic Radio Jets
• High-Sensitivity 86GHz (3.5mm) VLBI Observations of M87: Deep Imaging of the Jet Base at a 10 Schwarzschild-Radius Resolution
• Disk-Jet Connection in the Radio Galaxy 3C 120
• MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. VII. Blazar Jet Acceleration
• Poynting Flux Dominated Jets in Decreasing Density Atmospheres. I. The Non-relativistic Current-driven Kink Instability and the Formation of "Wiggled" Structures
• 3D Relativistic Magnetohydrodynamic Simulations of Current-Driven Instability. I. Instability of a static column
• MOJAVE XII: Acceleration and Collimation of Blazar Jets on Parsec Scales
• Faraday rotation and polarization gradients in the jet of 3C~120: Interaction with the external medium and a helical magnetic field?
• 3D Simulations of Relativistic Precessing Jets Probing the Structure of Superluminal Sources
• Erratic Jet Wobbling in the BL Lacertae Object OJ287 Revealed by Sixteen Years of 7mm VLBA Observations
• Stability Properties of Strongly Magnetized Spine Sheath Relativistic Jets
• A Multi-epoch VLBI Survey of the Kinematics of Caltech-Jodrell Bank Flat-Spectrum Sources, Part II: Analysis of the Kinematics
• Stability Properties of Magnetic Tower Jets
• Spatial growth of current-driven instability in relativistic rotating jets and the search for magnetic reconnection
• A multi-wavelength polarimetric study of the blazar CTA 102 during a Gamma-ray flare in 2012
• Can long-term periodic variability and jet helicity in 3C 120 be explained by jet precession?
• Studies of the Jet in BL Lacertae I. Recollimation Shock and Moving Emission Features
• The First Simultaneous 3.5 and 1.3mm Polarimetric Survey of Active Galactic Nuclei in the Northern Sky
• Structure and flux variability in the VLBI jet of BL Lacertae during the WEBT campaigns (1995--2004)
• A 3.5mm Polarimetric Survey of Radio-loud Active Galactic Nuclei
• Observational evidence for the link between the variable optical continuum and the subparsec-scale jet of the radio galaxy 3C 390.3
• Modeling the 3C 120 Radio Jet from 1 to 30 Milliarcseconds
• On the source of Faraday rotation in the jet of the radio galaxy 3C120
• Three-Dimensional Relativistic Magnetohydrodynamic Simulations of Current-Driven Instability with A Sub-Alfvenic Jet: Temporal Properties
• The connection between the radio jet and the gamma-ray emission in the radio galaxy 3C 120
• Relativistic plasma as the dominant source of the optical continuum emission in the broad-line radio galaxy 3C 120
• Variable circular polarisation associated with relativistic ejections from GRS 1915+105
• Resolving the inner parsec of the blazar J1924-2914 with the Event Horizon Telescope
• Modeling Helical Structures in Relativistic Jets
• Wavelet analysis of a large sample of AGN at high radio frequencies
• Mutiwavelength Observations of Radio Galaxy 3C 120 with XMM-Newton
• An Extremely Curved Relativistic Jet in PKS 2136+141
• The Trails of Superluminal Jet Components in 3C111
• A relativistic helical jet in the gamma-ray AGN 1156+295
• Warm Absorber Energetics in Broad Line Radio Galaxies
• A Multi-Epoch VLBI Survey of the Kinematics of CJF Sources; Part I: Model-Fit Parameters and Maps
• The connection between the parsec-scale radio jet and gamma-ray flares in the blazar 1156+295
• Modeling nuclei of radio galaxies from VLBI radio observations. Application to the BL Lac Object S5 1803+784
• Binary black holes in nuclei of extragalactic radio sources
• Modelling photometric reverberation data -- a disk-like broad-line region and a potentially larger black hole mass for 3C120
• High Resolution Radio Astronomy Using Very Long Baseline Interferometry
• Frequency-dependent time delays for strong outbursts in four blazars from the Metsahovi and UMRAO monitoring databases
• Unexpected High Brightness Temperature 140 PC from the Core in the Jet of 3C 120
• What Happened to the NGC 6251 Counterjet?
• Flare echos from relaxation shocks in perturbed relativistic jets
• Circularly polarised radio emission from GRS 1915+105 and other X-ray binaries
• Optical Emission and Particle Acceleration in a Quasi-Stationary Component in the Jet of OJ~287
• X-ray, UV, and Radio Timing Observations of the Radio Galaxy 3C 120
• Short Timescale Evolution of the Polarized Radio Jet during V404 Cygni's 2015 Outburst
• The dynamics of the parsec-scale jet in the neutrino blazar PKS 0735+178
• Revisiting 3C 279 jet morphology with space VLBI at 26 microarcsecond resolution
• Hints of correlation between broad-line and radio variations for 3C 120
• Multiple periodic oscillations in the radio light curves of NRAO 530
• VLBI Monitoring of the Sub-parsec-scale Jet in the Radio Galaxy 3C 66B at 22 GHz
• Multiple relativistic outbursts of GRS 1915+105: radio emission and internal shocks
• Relativistic jet motion in the core of the radio-loud quasar J1101+7225
• Extragalactic Relativistic Jets and Nuclear Regions in Galaxies
• Parsec-scale jet precession and a putative supermassive binary black hole system in the blazar AO 0235+164
• Probing the innermost regions of AGN jets and their magnetic fields with RadioAstron. V. Space and ground millimeter-VLBI imaging of OJ 287
• A Ring of Fire Orphan γ-Ray Flare in the Neutrino Candidate 3C 120
• Simulations of linear polarization of precessing AGN jets at parsec scales