Rotation Measures Across Parsec-Scale Jets of Fanaroff-Riley Type I Radio Galaxies

Kharb, P.; Gabuzda, D. C.; O’Dea, C. P.; Shastri, P.; Baum, Stefi A.

doi:10.1088/0004-637x/694/2/1485

Cited by 53 publications

(64 citation statements)

References 74 publications

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“…The above process using phase-referencing data greatly improve the image quality for 3C 66B, making it possible to image very weak extended jets, as reported by Asaki et al (2014) for water maser mapping. We cannot find a significant counterjet component at any epoch, in contrast with previous lower frequency results (Giovannini et al 2001;Kharb et al 2009). The lower limit of the jet-to-counterjet intensity ratio from our 22 GHz image is 3, which is consistent with the reported values.…”

Section: Observations and Data Reductioncontrasting

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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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 Reductioncontrasting

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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“…Observed intensity profiles of the radio galaxy 3C 78 and blazar NRAO 140 1 are shown in Figs 3(a) and (b), respectively. 3C 78 is a radio galaxy with θ ob ∼ 1 and a mildly relativistic parsec scale jet (β≤ 0.52) as indicated by its parsec scale jet to counterjet surface brightness ratio (Kharb et al 2009). The symmetry of 3C 78's profile may be explained by the fact that the jet frame line of sight is perpendicular to the jet axis, or it is possible that the finite beamwidth smears out any small skewness the true intensity profile contains.…”

Section: Intensity Profilesmentioning

confidence: 99%

“…Further details regarding the observations of the intensity profiles and other observables covered in are as follows. The observations for 3C 78 were carried out with the VLBA and Effelsberg on 2005 September 10 (Kharb et al 2009). NRAO 140 was observed as part of the MOJAVE program with the VLBA on 2007 August 9.…”

Section: Intensity Profilesmentioning

confidence: 99%

Signatures of large-scale magnetic fields in active galactic nuclei jets: transverse asymmetries

Clausen-Brown

Lyutikov

Kharb

2011

Monthly Notices of the Royal Astronomical Society

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We investigate the emission properties that a large‐scale helical magnetic field imprints on active galactic nuclei (AGN) jet synchrotron radiation. A cylindrically symmetric relativistic jet and large‐scale helical magnetic field produce significant asymmetrical features in transverse profiles of fractional linear polarization, intensity, the Faraday rotation and spectral index. The asymmetrical features of these transverse profiles correlate with one another in ways specified by the handedness of the helical field, the jet viewing angle (θob) and the bulk Lorentz factor of the flow (Γ). Thus, these correlations may be used to determine the structure of the magnetic field in the jet. In the case of radio galaxies (θob∼ 1 rad) and a subclass of blazars with particularly small viewing angles (θob≪ 1/Γ), we find an edge‐brightened intensity profile that is similar to that observed in the radio galaxy M87. We present observations of the AGNs 3C 78 and NRAO 140 that display the type of transverse asymmetries that may be produced by large‐scale helical magnetic fields.

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“…Such gradients are expected if the sheath is threaded by a helical magnetic field due to the change in the line of sight component of the magnetic field across the jet [7]. Further observations have also provide evidence for the existence of such gradients in other sources (e.g., [8][9][10][11][12][13]). However, [14] have raised concerns about the claimed transverse RM gradients by arguing that most of these observations lack the necessary resolution transverse to the jet.…”

Section: Introductionmentioning

confidence: 80%

Faraday rotation in jets of AGN: the case of 3C 120

Gómez

Roca-Sogorb

Agudo

et al. 2012

J. Phys.: Conf. Ser.

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Abstract. The source of Faraday rotation in the jet of the radio galaxy 3C 120 is analyzed through Very Long Baseline Array observations carried out between 1999 and 2007 at 15, 22 and 43 GHz. Uncorrelated changes in the linear polarization of the underlying jet emission and the Faraday rotation screen indicate that the emitting jet and the source of Faraday rotation are not closely connected physically and have different configurations for the magnetic field and/or kinematical properties. Furthermore, the existence of a region of enhanced rotation measure whose properties remain constant over three years requires a localized source of Faraday rotation, favoring a model in which a significant fraction of the rotation measure originates in foreground clouds.

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Rotation Measures Across Parsec-Scale Jets of Fanaroff-Riley Type I Radio Galaxies

Cited by 53 publications

References 74 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

Signatures of large-scale magnetic fields in active galactic nuclei jets: transverse asymmetries

Faraday rotation in jets of AGN: the case of 3C 120

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