The kinematics in the pc-scale jets of AGN The case of S5 1803+784

Abstract

We present a kinematic analysis of jet component motion in the VLBI jet of the BL Lac object S5 1803+784, which does not reveal long-term outward motion for most of the components. Understanding the complex kinematic phenomena can possibly provide insights into the differences between quasars and BL Lac objects. The blazar S5 1803+784 has been studied with VLBI at $\nu$ =1.6, 2.3, 5, 8.4, and 15 GHz between 1993.88 and 2005.68 in 26 observing runs. We (re)analyzed the data and present Gaussian model-fits. We collected the already published kinematic information for this source from the literature and re-identified the components according to the new scenario presented in this paper. Altogether, 94 epochs of observations have been investigated. A careful study of the long-term kinematics reveals a new picture for component motion in S5 1803+784. In contrast to previously discussed motion scenarios, we find that the jet structure within 12 mas of the core can most easily be described by the coexistence of several bright jet features that remain on the long-term at roughly constant core separations (in addition to the already known {\it stationary} jet component $\sim$ 1.4 mas) and one faint component moving with an apparent superluminal speed ($\sim$ 19c, based on 3 epochs). While most of the components maintain long-term roughly constant distances from the core, we observe significant, smooth changes in their position angles. We report on an evolution of the whole jet ridge line with time over the almost 12 years of observations. The width of the jet changes periodically with a period of $\sim$ 8 to 9 years. We find a correlation between changes in the position angle and maxima in the total flux-density. We present evidence for a geometric origin of the phenomena and discuss possible models.

The manuscript will be published by A&A

References in corpus (7)

• MOJAVE: Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. VI. Kinematics Analysis of a Complete Sample of Blazar Jets
• Sub-milliarcsecond Imaging of Quasars and Active Galactic Nuclei III. Kinematics of Parsec-Scale Radio Jets
• A Multi-epoch VLBI Survey of the Kinematics of Caltech-Jodrell Bank Flat-Spectrum Sources, Part II: Analysis of the Kinematics
• The role of Kelvin-Helmholtz instability in the internal structure of relativistic outflows. The case of the jet in 3C 273
• Relativistic Jets in The Radio Reference Frame Image Database I: Apparent Speeds from the First Five Years of Data
• A Multi-Epoch VLBI Survey of the Kinematics of CJF Sources; Part I: Model-Fit Parameters and Maps
• Frequency-dependent time delays for strong outbursts in four blazars from the Metsahovi and UMRAO monitoring databases

Cited by in corpus (32)

• The variability timescales and brightness temperatures of radio flares from stars to supermassive black holes
• A spinning supermassive black hole binary model consistent with VLBI observations of the S5 1928+738 jet
• The Relativistic Jet Dichotomy and the End of the Blazar Sequence
• Studies of the Jet in BL Lacertae. II. Superluminal Alfvén Waves
• Connection between inner jet kinematics and broadband flux variability in the BL Lac object S5 0716+714
• Precession-induced Variability in AGN Jets and OJ 287
• Multi-messenger approaches to binary supermassive black holes in the "continuous-wave" regime
• VLBI radio structure and radio brightening of the high-energy neutrino emitting blazar TXS 0506+056
• A possible jet precession in the periodic quasar B0605-085
• Understanding BL Lac objects Structural & kinematic mode changes in the BL Lac object PKS 0735+178
• Polarization structure in the core of 1803+784: a signature of recollimation shocks?
• Neutrinos from active black holes, sources of ultra high energy cosmic rays
• VLBA polarimetric monitoring of 3C 111
• A Recollimation Shock in a Stationary Jet Feature with Limb-brightening in the Gamma-ray Emitting Narrow-line Seyfert 1 Galaxy 1H 0323+342
• Frequency dependent core shifts and parameter estimation for the blazar 3C 454.3
• High-frequency very long baseline interferometry studies of NRAO 530
• Flux variability from ejectas in structured relativistic jets with large-scale magnetic fields
• A kinematic study of the compact jet in quasar B3 1633+382
• The variability of blazars throughout the electromagnetic spectrum
• Flaring radio lanterns along the ridge line: long-term oscillatory motion in the jet of S5 1803+784
• The parsec-scale jet of PKS 1749+096
• Flare echos from relaxation shocks in perturbed relativistic jets
• Deconstructing blazars: A different scheme for jet kinematics in flat-spectrum AGN
• Multi-wavelength flare observations of the blazar S5 1803+784
• Gamma-rays in flat-spectrum AGN: Revisiting the fast jet hypothesis with the CJF sample
• Correlations between the peak flux density and the position angle of inner-jet in three blazars
• Very Large Array imaging rules out precessing radio jets in three DES$-$SDSS-selected candidate periodic quasars
• The non-ballistic superluminal motion in the plane of the sky-II
• Possible Gravitational Microlensing Events in the Optical Lightcurve of Active Galaxy S5 0716+714
• AGN jets under the microscope: A divide?
• Unveiling the Complex Jet Dynamics in the Blazar 2021+317 through Multi-Epoch VLBI Observations
• The Application of Ridgelines in Extended Radio Source Cross-Identification