A multi-epoch VLBI survey of the kinematics of CJF sources

Britzen, S.; Vermeulen, R. C.; Taylor, G. B.; Campbell, R. M.; Pearson, T. J.; Readhead, A. C. S.; Xu, W.; Browne, I. W. A.; Henstock, D. R.; Wilkinson, P. N.

doi:10.1051/0004-6361:20052677

Cited by 32 publications

(72 citation statements)

References 61 publications

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“…Instead, model components remain at similar core separations in the investigated time span. This is in contrast to previous studies of jet component motion in AGN, where components tend to show predominantly outward motion (e.g., Britzen et al 2007Britzen et al , 2008. In contrast to previous studies -that relied mainly on investigating the core separation evolution -we study the positionangle evolution with time as well.…”

Section: Apparent Stationarity and Non-radial Motion Of Jet Componentsmentioning

confidence: 87%

“…A rather large range in proper motions (0.05 mas/yr-1.11 mas/yr) has been reported by different authors based on the investigation of an increasing core separation with time modeled for jet components in this source (e.g., Eckart et al 1987;Witzel et al 1988;Schalinski et al 1992;Gabuzda et al 1998;Jorstad et al 2001;Pérez-Torres et al 2004;Kellermann et al 2004;Bach et al 2005;Rastorgueva et al 2008). Based on these results it is not clear, whether S5 0716+714 reveals slow apparent velocities typical for BL Lac objects (e.g., Britzen et al 2007) or faster apparent velocities more typical for quasars (e.g., Kellermann et al 2004).…”

Section: Introductionmentioning

confidence: 94%

“…In an earlier publication of the results relying on the 15 GHz data only, we presented a description of preliminary results (Britzen et al 2006). A detailed description of the data reduction, analysis, and investigation is presented in .…”

Section: Introductionmentioning

confidence: 99%

“…Kellermann et al 2004). 4 observations were taken from the CJF-survey (Britzen et al 2007). S5 0716+714 was used as calibrator source for observations targeted at NRAO 150 (Agudo et al 2007) in 6 epochs.…”

Section: Introductionmentioning

confidence: 99%

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Non-radial motion in the TeV blazar S5 0716+714

Britzen¹,

Kam²,

Witzel³

et al. 2009

A&A

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Context. Flat-spectrum radio sources often show a core-jet structure on pc-scales. Individual jet components reveal predominantly outward directed motion. For the BL Lac object S5 0716+714 conflicting apparent velocities have been reported in the literature. This object is an intra-day variable source and suited to investigate a possible correlation between kinematic properties and flux-density variability on different timescales. Aims. We study the kinematics in the pc-scale jet of S5 0716+714 to determine the apparent speeds of the jet components based on a much improved data set. In addition, we search for correlations between the radio flux-density light curves and the morphological changes detected along the VLBI jet. Methods. We (re-)analyze 50 VLBI observations obtained with the VLBA at 5 different frequencies (5-43 GHz) between 1992.73 and 2006.32. The data have been parameterized using circular Gaussian components. We analyze the jet component motion in detail taking care not only to account for motion in the radial but also in the orthogonal direction. We study the evolution of the jet ridge line and investigate the spectral properties of the individual components. We search for correlations between radio band light curves and the kinematic properties of the jet components. Results. We present an alternative kinematic scenario for jet component motion in S5 0716+714. We present evidence for the apparent stationarity of jet components (with regard to their core separation) with time. Jet components, however, do seem to move significantly non-radially with regard to their position angle and in a direction perpendicular to the major axis of the jet. We discuss a possible correlation between the long-term radio flux-density variability and apparent jet component motions. Conclusions. In S5 0716+714 an alternative motion scenario is proposed. With regard to the core separation, rather stationary components can fit the VLBI observations well. A new model to explain the observed motion with regard to the position angle is required. Based on the correlation between the longterm radio flux-density variability and the position angle evolution of a jet component, we conclude that a geometric contribution to the origin of the long-term variability might not be negligible. Subluminal motion has been reported for most of the TeV blazars. Our analysis also confirms this finding for the case of S5 0716+714. This result increases the number of TeV blazars showing apparent subluminal motion to 7.

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Section: Apparent Stationarity and Non-radial Motion Of Jet Componentsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Non-radial motion in the TeV blazar S5 0716+714

Britzen¹,

Kam²,

Witzel³

et al. 2009

A&A

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“…However, as more detailed VLBI-monitoring reveals, this model can not easily explain all the observed motion phenomena in a growing number of AGN. In many sources stationary features or even motion towards the core have been observed (e.g., Alberdi et al 2000;Kellermann et al 2004;Britzen et al 2007).…”

Section: Introductionmentioning

confidence: 99%

The kinematics in the pc-scale jets of AGN

Britzen¹,

Kudryavtseva

Witzel³

et al. 2010

A&A

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Context. BL Lac objects show core-jet structures with features moving outwards along the jet. We present a kinematic analysis of jet component motion in the pc-scale jet of the BL Lac object S5 1803+784, which does not reveal long-term outward motion for most of the components. Aims. S5 1803+784 shows complex kinematic phenomena; understanding these provides new insights into the emission processes in BL Lac objects and possibly into the differences between quasars and BL Lac objects. Methods. The blazar S5 1803+784 has been studied with VLBI at ν = 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. Results. A careful study of the long-term kinematics reveals a new picture for jet 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 "stationary" jet component ∼1.4 mas) and one faint component moving with an apparent superluminal speed (∼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 ∼8−9 years. We find a correlation between changes in the position angle and maxima in the total flux-density light-curves. We present evidence for a geometric origin of the observed phenomena and discuss possible models. Conclusions. We find evidence for a significantly different scenario of jet component motion in S5 1803+784 compared to the generally accepted one of outwardly moving jet components, and conclude that the observed phenomena (evolution of the jet ridge line, roughly constant component core separations but with significant position angle changes) can most easily be explained within a geometric model.

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Observational Details: Radio

Bridle

Cohen

2012

Relativistic Jets From Active Galactic Nuclei

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A multi-epoch VLBI survey of the kinematics of CJF sources

Cited by 32 publications

References 61 publications

Non-radial motion in the TeV blazar S5 0716+714

Non-radial motion in the TeV blazar S5 0716+714

The kinematics in the pc-scale jets of AGN

Observational Details: Radio

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