A supermassive binary black hole in the quasar 3C 345

Lobanov, A. P.; Roland, J.

doi:10.1051/0004-6361:20041831

Cited by 118 publications

(177 citation statements)

References 62 publications

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“…SMBH), precession can occur as a result of the Bardeen-Petterson effect (Caproni et al 2006), magnetic torques (Lai 2003) or magnetohydrodynamic instabilities, prominently Kelvin-Helmholtz instabilities (e.g., Camenzind & Krockenberger 1992; Hardee & Norman 1988;Birkinshaw 1991;Zhao et al 1992;Hardee et al 1994;Hardee et al 1997;Meier & Nakamura 2006;Perucho et al 2006). If we assume that the AGN core hosts a binary system (presumably a binary black hole, BBH) then precession can occur as a result of the orbital motion of the binary system (e.g., Lobanov & Roland 2005;Roos et al 1993;Kaastra & Roos 1992), tidal forces, gravitational torques (e.g., Katz 1997;Romero et al 2000), as well as orbital motion of the system around the galactic gravity center (Roland et al 2008). …”

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

confidence: 99%

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: 99%

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

Britzen¹,

Kam²,

Witzel³

et al. 2009

A&A

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“…However, these ejection angles are distributed in a random rather than systematic manner, and therefore do not appear to be consistent with a precessing jet scenario. On the other hand, the variation timescale of the jet ejection angle seems to be much shorter than the precession period (Lobanov & Roland 2005). Britzen et al (2010b) recently pointed out that BL Lac objects differ appreciably in the parsec-scale jet kinematics from quasars.…”

Section: Structure Variabilitymentioning

confidence: 99%

The parsec-scale jet of PKS 1749+096

Shen

Krichbaum

et al. 2012

A&A

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Context. PKS 1749+096 is a BL Lac object showing weak extended jet emission to the northeast of the compact VLBI core on parsec scales. Aims. We aim at better understanding the jet kinematics and variability of this source and finding clues that may applicable to other BL Lac objects. Methods. The jet was studied with multi-epoch multi-frequency high-resolution VLBI observations. Results. The jet is characterized by a one-sided curved morphology at all epochs and all frequencies. The VLBI core, located at the southern end of the jet, was identified based on its spectral properties. The equipartition magnetic field of the core was investigated, through which we derived a Doppler factor of 5, largely consistent with that derived from kinematics (component C5). The study of the detailed jet kinematics at 22 and 15 GHz, spanning a period of more than 10 years, indicates the possible existence of a bimodal distribution of the jet apparent speed. Ballistic and non-ballistic components are found to coexist in the jet. Superluminal motions in the range of 5-21 c were measured in 11 distinct components. We estimated the physical jet parameters with the minimum Lorentz factor of 10.2 and Doppler factors in the range of 10.2-20.4 (component C5). The coincidence in time of the component's ejection and flares supports the idea that, at least in PKS 1749+096, ejection of new jet components is connected with major outbursts in flux density. For the best-traced component (C5) we found that the flux density decays rapidly as it travels downstream the jet, accompanied by a steepening of its spectra, which argues in favor of a contribution of inverse Compton cooling. These properties make PKS 1749+096 a suitable target for an intensive monitoring to decipher the variability phenomenon of BL Lac objects.

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“…Gravitational perturbations associated with this orbiting secondary black hole can disrupt the accretion disk of the primary black hole and lead to precession. Lobanov & Roland (2005) argue that in light of the "two-fluid" model, the orbital motion and the disk precession can lead to curving and wiggling of the jet. Furthermore, they propose that for strong enough magnetic fields, the K-H instabilities can be considered negligible.…”

Section: Models Relying On a Binary Black Holementioning

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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A supermassive binary black hole in the quasar 3C 345

Cited by 118 publications

References 62 publications

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

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

The parsec-scale jet of PKS 1749+096

The kinematics in the pc-scale jets of AGN

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