Multi-epoch VLBA observations of 3C 66A

Cai, H.-B.; Shen, Zhi-Qiang; Sudou, Hiroshi; Shang, L.-L.; Iguchi, Satoru; Murata, Yasuhiro; Taniguchi, Yoshiaki; Wakamatsu, K.; Takaba, Hiroshi

doi:10.1051/0004-6361:20077155

Cited by 8 publications

(8 citation statements)

References 19 publications

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“…The images of 3C 66A were made using CLEAN with uniform weighting and a self-calibration technique. They are in good agreement with previous results from the same data sets (Cai et al 2007;Zhao et al 2014). The final solutions for the amplitude and phase obtained by self-calibration of 3C 66A for a time interval of 0.1 min were applied to the 3C 66B data to calibrate the results for short period variations due to atmospheric effects.…”

Section: Observations and Data Reductionsupporting

confidence: 93%

“…In this paper, we focus on the improvement in the image quality, and we will present the astrometric results in a separate paper. The 22 GHz observations consisted of nodding-mode observations of 3C 66A and 3C 66B with a switching cycle of 30 s. 3C 66A is a very bright quasar exhibiting a compact core and one-sided southward jet (Taylor et al 1996;Jorstad et al 2001;Cai et al 2007;Zhao et al 2014). Since this source is very close in the sky to 3C 66B (∼ 0.1 degree, it is a very good source for phase and amplitude calibration of 3C 66B.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

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VLBI Monitoring of the Sub-parsec-scale Jet in the Radio Galaxy 3C 66B at 22 GHz

Sudou

Iguchi

Zhao

2017

ApJ

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We present measurements of the proper motion of the sub-parsec scale jet at 22 GHz in the nearby FR I galaxy 3C 66B. Observations were made using the VLBA at six epochs over four years. A phase-referencing technique was used to improve the image quality of the weak and diffuse jet components. We find that the inner knots are almost stationary, though one of them was expected to be detected with an apparent speed of 0.2 mas yr −1 according to 8 GHz monitoring at the same observation epochs. Clear flux variations are not observed in the core at 22 GHz; in contrast, clear flux enhancement is observed in the core at 8 GHz. We discuss a possible explanation: If the jet has helical structure, the viewing angle of the jet at 8 and 22 GHz differ by a few degrees if the jet direction is almost along our line of sight. Although these results may imply the existence of a two-zone jet, which has been suggested in certain radio galaxies, it cannot explain the fact that the jet at the higher frequency is slower than that at the lower frequency.

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Section: Observations and Data Reductionsupporting

confidence: 93%

Section: Observations and Data Reductionmentioning

confidence: 99%

VLBI Monitoring of the Sub-parsec-scale Jet in the Radio Galaxy 3C 66B at 22 GHz

Sudou

Iguchi

Zhao

2017

ApJ

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“…The number of extragalactic radio sources with reported core shift has been increasing (Cai et al 2007; Kovalev et al 2008; O’Sullivan & Gabuzda 2009, and references therein). Kovalev et al (2008) studied a core shift sample of 29 active galactic nuclei between 2.3 and 8.4 GHz.…”

Section: Resultsmentioning

confidence: 99%

High-frequency very long baseline interferometry studies of NRAO 530

Lu¹,

Krichbaum²,

Zensus³

2011

Monthly Notices of the Royal Astronomical Society

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NRAO 530 is an optically violent variable source and has been studied with multi‐epoch multifrequency high‐resolution very long baseline interferometry (VLBI) observations. NRAO 530 was monitored with the Very Long Baseline Array (VLBA) at three frequencies (22, 43 and 86 GHz) on 10 consecutive days in 2007 May during observations of the Galactic Centre (Sgr A*). Furthermore, analysis of archival data of NRAO 530 at 15 GHz over the last 10 years allows us to study its detailed jet kinematics. We identified the compact component located at the southern‐end of the jet as the VLBI core, consistent with previous studies. The 10‐d monitoring data at the three high frequencies were shown to produce high‐quality and self‐consistent measurements of the component positions, from which we detected for the first time a two‐dimensional frequency‐dependent position shift. In addition, the repeated measurements also permit us to investigate the interday flux density and structure variability of NRAO 530. We find that it is more variable for the inner jet components than those further out. We obtained apparent velocities for eight jet components with βapp ranging from 2 to 26c. Accordingly, we estimated physical jet parameters with the minimum Lorentz factor of 14 and Doppler factors in the range of 14–28 (component f). The changes in the morphology of NRAO 530 were related to the motion of separate jet components with the most pronounced changes occurring in the regions close to the core. For NRAO 530, we estimated a position angle swing of 34 per year for the entire inner jet (components d and e). The non‐ballistic motion and change of jet orientation make this source another prominent example of a helical and possibly ‘swinging’ jet.

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“…Simple fitting error analysis of the flux density leads to very small errors (typi-cally 1 mJy). We added flux errors to 10 % of the measured integrated flux density by assuming the typical accuracy of the absolute amplitude calibration of the VLBA (Cai et al 2007).…”

Section: Proper Motion Of the Jetmentioning

confidence: 99%

Proper Motion of the Sub-Parsec-Scale Jet in the Radio Galaxy 3c 66b

Sudou

Iguchi

2011

The Astronomical Journal

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We present proper motion of the sub-parsec scale jet in a nearby elliptical galaxy 3C 66B. Observations were made using the VLBA and partly Effelsburg 100-m telescope at 2.3 GHz and 8.4 GHz at 10 epochs over 4 years. The 8.4 GHz images showed that a proper motion increases from 0.21 to 0.70 mas year −1 , corresponding to an apparent speed of 0.30 c to 0.96 c, with a distance from the core on a sub-parsec scale. Our investigation suggests that the apparent increase of the proper motion can be explained by changes in the viewing angle, according to a relativistic beaming model. However, we still cannot eliminate the possibility that acceleration of the jet outflow speed or of changes of emissivity profile in the two-zone jet might be found in 3C 66B.

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Multi-epoch VLBA observations of 3C 66A

Cited by 8 publications

References 19 publications

VLBI Monitoring of the Sub-parsec-scale Jet in the Radio Galaxy 3C 66B at 22 GHz

VLBI Monitoring of the Sub-parsec-scale Jet in the Radio Galaxy 3C 66B at 22 GHz

High-frequency very long baseline interferometry studies of NRAO 530

Proper Motion of the Sub-Parsec-Scale Jet in the Radio Galaxy 3c 66b

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