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

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

doi:10.1051/0004-6361:20077717

Cited by 89 publications

(142 citation statements)

References 58 publications

Supporting

Mentioning

128

Contrasting

Unclassified

Order By: Relevance

“…The apparent pattern speeds measured in the TeV blazars are considerably slower than those measured in sources selected for their compact radio emission (e.g., CJF: Britzen et al 2008), or for their GeV gamma-ray emission (Jorstad et al 2001). S5 0716+714 has most recently been detected in the TeV-regime as well.…”

Section: Tev Blazars and Subluminal Motionmentioning

confidence: 78%

“…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: 88%

“…We are aware of the problems involved when tracing and identifying components through the epochs. A detailed discussion of the problems and uncertainties involved has been published by us in Britzen et al (2008) with regard to the analysis of the kinematics of the CJF-survey (for 293 AGN). Whereas in most VLBI data analyses the small number of observations hampers a proper component identification the situation is much better in the case of 0716+714 with a comparably large number of data sets.…”

Section: Component Identificationmentioning

confidence: 99%

See 2 more Smart Citations

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

Britzen¹,

Kam²,

Witzel³

et al. 2009

A&A

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Tev Blazars and Subluminal Motionmentioning

confidence: 78%

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

confidence: 88%

Section: Component Identificationmentioning

confidence: 99%

See 1 more Smart Citation

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

Britzen¹,

Kam²,

Witzel³

et al. 2009

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…A detailed discussion of model-fitting uncertainties and their influence on the parameters is presented in Britzen et al (2007Britzen et al ( , 2008. The uncertainties of each data set in general are influenced by different u-v coverages, calibrations, sensitivities, etc.…”

Section: Determination Of the Uncertaintiesmentioning

confidence: 99%

The kinematics in the pc-scale jets of AGN

Britzen¹,

Kudryavtseva

Witzel³

et al. 2010

A&A

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…Britzen et al (2008) develop a localized method for calculating the bending of the jet associated with individual components. The maximum of the distribution of local angles is at zero degrees, although a substantial fraction shows some bending (0−40 degrees).…”

Section: Radio Emissionmentioning

confidence: 99%

Tracing the merger-driven evolution of active galaxies using the CJF sample

Karouzos¹,

Britzen²,

Eckart

et al. 2010

A&A

Self Cite

View full text Add to dashboard Cite

Context. For the evolution of large-scale structures in the Universe, it is unclear whether active galaxies represent a phase that each galaxy undergoes, and whether and to which extent the evolution of black holes at their centers is important. Binary black hole (BBH) systems may play a key role in our understanding of the above questions. Aims. We investigate the Caltech-Jodrell Bank flat-spectrum (CJF) sample to identify evidence that supports the merger-driven evolution scheme of active galaxies, and search for tracer-systems of active galactic nucleus (AGN) evolution and possible BBH candidates. We discuss the strength of and uncertainty in the evidence and formulate a set of selection criteria to detect such tracer-systems. Methods. We conduct an extensive literature search for all available multiwavelength data, particularly in the optical and infrared regime, and morphological information about the CJF sources. We perform a statistical analysis of the properties of this sample. Results. We find 1 ULIRG (Mrk 231) included in the CJF prototype of a transitory system. In total, 28.6% of the CJF sources with z ≤ 0.4 are distorted or have a companion. Given the unbiased sample used here, this provides strong evidence of the ubiquity of the merger phenomenon in the context of active galaxies. We find a correlation between the radio and the near-infrared luminosity of the high-luminosity sources, interpreted in the context of the interplay between a star-formation and AGN component. We find a connection between variability and evolutionary transitory systems, as selected on the basis of their near-infrared colors. We select 28 sources that trace the different evolution phases of an AGN, as well as a number of the most promising BBH candidates. We find 4 sources with almost periodical variability in the optical and radio on similar timescales.

show abstract

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

Cited by 89 publications

References 58 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

Tracing the merger-driven evolution of active galaxies using the CJF sample

Contact Info

Product

Resources

About