Non-ballistic superluminal motion in the plane of the sky - II.

Gong, Biping; Kong, S. W.; Xue, F.; Li, Y.; Huang, Yang H.

doi:10.1111/j.1365-2966.2011.19632.x

Cited by 5 publications

(4 citation statements)

References 28 publications

(104 reference statements)

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“…An additional mechanism or effect must be introduced to produce a wide jet. The precession of the jet axis, or the assumption that the components follow non-ballistic and non-linear paths, can lead to such jet properties (e.g., Steffen et al 1995;Gong 2008;Roland et al 2008;Gong et al 2011). In these models, jet components follow highly curved trajectories, which, viewed face-on, would give the impression of a wider distribution of jet component position angles.…”

Section: Possible Explanationsmentioning

confidence: 99%

Deconstructing blazars: A different scheme for jet kinematics in flat-spectrum AGN

Karouzos¹,

Britzen²,

Witzel³

et al. 2012

A&A

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Context. Recent VLBI studies of the morphology and kinematics of individual BL Lac objects (S5 1803+784, PKS 0735+178, etc.) have revealed a new paradigm for the pc-scale jet kinematics of these sources. Unlike the apparent superluminal outward motions usually observed in blazars, most, if not all, jet components in these sources appear to be stationary with respect to the core, while exhibiting strong changes in their position angles. As a result, the jet ridge lines of these sources evolve substantially, at times forming a wide channel-flow. Aims. We investigate the Caltech-Jodrell Bank flat-spectrum (CJF) sample of radio-loud active galaxies to study this new kinematic scenario for flat-spectrum AGN. Comparing BL Lac objects and quasars in the CJF, we look for differences in the kinematics and morphologies of their jet ridge lines. The large number of sources in the CJF sample, together with the excellent kinematical data available, allow us to perform a robust statistical analysis in this context. Methods. We develop a number of tools to extract information about the apparent linear and angular evolution of the CJF jet ridge lines, as well as their morphology. We study both the radial and non-radial apparent motions in the CJF jets. A statistical analysis of the extracted information allows us to test this new kinematic scenario and assess the importances of the radial and non-radial motions in flat-spectrum AGN jets in general and especially in BL Lacs compared to quasars. We also use these tools to check the kinematics for (multi-wavelength) variable AGN. Results. We find that approximately half of the sample display appreciable apparent jet widths (>10 degrees), with BL Lac jet ridge lines showing significantly larger apparent widths than those of both quasars and radio galaxies. In addition, BL Lac jet ridge lines are found to change their apparent width more strongly. Finally, BL Lac jet ridge lines show the least apparent linear evolution, which translates into the smallest apparent expansion speeds for their components. We find compelling evidence supporting a substantially different kinematic scenario for flat-spectrum radio-AGN jets and in particular for BL Lac objects. In addition, we find that variability is closely related to the properties of a source's jet ridge line. Variable quasars are found to have "BL Lac like" behavior, relative to their non-variable counterparts.

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Section: Possible Explanationsmentioning

confidence: 99%

Deconstructing blazars: A different scheme for jet kinematics in flat-spectrum AGN

Karouzos¹,

Britzen²,

Witzel³

et al. 2012

A&A

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“…A precession of the jet nozzle can be due to e.g., double super-massive black holes or other reasons (see Britzen et al 2010a and references therein). For the non-ballistic jet, models have been proposed e.g., Gong et al (2011), also see Lister et al (2009b) and Britzen et al (2009Britzen et al ( , 2010aBritzen et al ( , 2010b for discussions. In these models, a non-ballistic motion of jet is largely related to the jet interaction with ambient matter.…”

Section: Figmentioning

confidence: 99%

“…This is consisting with the sub-luminal motion or the 'stationary scenario' of 0716+714, as proposed by Britzen et al (2009). In general, a non-ballistic jet is likely to be formed, through the shocked jet plasma working on the surrounding medium (Gong et al 2011), and a helical like trajectory of the jet ridge-line would be expected.…”

Section: Figmentioning

confidence: 99%

Correlations between the peak flux density and the position angle of inner-jet in three blazars

Liu

et al. 2012

Astrophys Space Sci

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Aims. We aim to investigate the relation between the long-term flux density and the position angle (PA) evolution of inner-jet in blazars. Methods. We have carried out the elliptic Gaussian model-fit to the 'core' of 50 blazars from 15 GHz VLBA data, and analyzed the variability properties of three blazars from the model-fit results. Results. Diverse correlations between the long-term peak flux density and the PA evolution of the major axis of the 'core' have been found in ∼ 20% of the 50 sources. Of them, three typical blazars have been analyzed, which also show quasi-periodic flux variations of a few years (T). The correlation between the peak flux density and the PA of inner-jet is positive for S5 0716+714, and negative for S4 1807+698. The two sources cannot be explained with the ballistic jet models, the non-ballistic models have been analyzed to explain the two sub-luminal blazars. A correlation between the peak flux density and the PA (with a T/4 time lag) of inner-jet is found in [HB89] 1823+568, this correlation can be explained with a ballistic precession jet model. All the explanations are based mainly on the geometric beaming effect; physical flux density variations from the jet base would be considered for more complicated situations in future, which could account for the no or less significance of the correlation between the peak flux density and the PA of inner-jet in the majority blazars of our sample. Conclusions.

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“…An additional mechanism or effect must be introduced to produce a wide jet. Precession of the jet axis, or assuming that the components follow non-ballistic and non-linear paths, can lead to such jet properties (e.g., Steffen et al 1995b;Gong 2008;Roland et al 2008;Gong et al 2011). In these models, jet components follow highly curved trajectories, which, viewed face-on, would give the impression of a wider distribution of jet component position angles.…”

Section: Possible Explanationsmentioning

confidence: 99%

AGN jets under the microscope: A divide?

et al. 2012

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A new paradigm for active galactic jet kinematics has emerged through detailed investigations of BL Lac objects using very long baseline radio interferometry. In this new scheme, most, if not all, jet components appear to remain stationary with respect to the core but show significant non-radial motions. This paper presents results from our kinematic investigation of the jets of a statistically complete sample of radio-loud flat-spectrum active galaxies, focusing on the comparison between the jet kinematic properties of BL Lacs and flat-spectrum radio-quasars. It is shown that there is a statistically significant difference between the kinematics of the two AGN classes, with BL Lacs showing more bent jets, that are wider and show slower movement along the jet axis, compared to flat-spectrum radio-quasars. This is interpreted as evidence for helically structured jets.

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Non-ballistic superluminal motion in the plane of the sky - II.

Cited by 5 publications

References 28 publications

Deconstructing blazars: A different scheme for jet kinematics in flat-spectrum AGN

Deconstructing blazars: A different scheme for jet kinematics in flat-spectrum AGN

Correlations between the peak flux density and the position angle of inner-jet in three blazars

AGN jets under the microscope: A divide?

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