Very Long Baseline Array Polarimetry of Three Powerful Radio Galaxy Cores

Taylor, G. B.; Hough, D. H.; Venturi, T.

doi:10.1086/322355

Cited by 14 publications

(15 citation statements)

References 24 publications

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“…A similar result was found for the radio galaxy 3C 166, which has a rest-frame RM of À2300 rad m À2 for its inner jet and has a depolarized core (Taylor, Hough, & Venturi 2001). The highest parsec-scale RM in the rest frame (20,000-40,000 rad m À2 ) still belongs to the quasar OQ 172 (Udomprasert et al 1997), so RMs of the order of 10,000 rad m À2 do not belong exclusively to the radio galaxies.…”

Section: Rotation Measure Versus Core Dominancesupporting

confidence: 74%

A View through Faraday’s Fog: Parsec‐Scale Rotation Measures in Active Galactic Nuclei

Zavala

Taylor

2003

ApJ

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Rotation measure observations of nine quasars, four BL Lacertae objects, and three radio galaxies are presented. The rest-frame rotation measures in the cores of the quasars and the jets of the radio galaxy M87 are several thousand rad m À2 . The BL Lac objects and the jets of the quasars have rest-frame rotation measures of a few hundred rad m À2 . A core rotation measure of 500 rad m À2 in the rest frame is suggested as the dividing line between quasars and BL Lac objects. The substantial rotation measures of the BL Lac objects and quasars cast doubt on the previous polarization position angle investigations of these objects at frequencies of 15 GHz or less. BL Lac itself has a rotation measure that varies in time, similar to the behavior observed for the quasars 3C 273 and 3C 279. A simple model with magnetic fields of 40 lG or less can account for the observed rotation measures.

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Section: Rotation Measure Versus Core Dominancesupporting

confidence: 74%

A View through Faraday’s Fog: Parsec‐Scale Rotation Measures in Active Galactic Nuclei

Zavala

Taylor

2003

ApJ

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“…Most of the flux comes from a central source located at (Δα, Δδ) ∼ (+0.6 ± 0.1 , +0.4 ± 0.1 ) at both frequencies. This corresponds within the errors with the position of the AGN core determined in the VLBI 1.7 and 5 GHz maps (component B2 in Schilizzi et al 2001;Taylor et al 2001) and is therefore adopted as the best guess for the dynamical center of 3C 236 (component labeled "AGN" in Fig. 1).…”

Section: Ancillary Datasupporting

confidence: 59%

“…1). The NW 1 mm and 3 mm components are both fitted by a point source located at (Δα, Δδ) ∼ (+0.0 ± 0.1 , +0.8 ± 0.1 ), i.e., at a position intermediate between the jet components A (radio lobe) and B1 (base of the radio jet) identified in the VLBI 1.7 and 5 GHz maps of Schilizzi et al (2001) and Taylor et al (2001). This indicates that the NW elongations identified in Fig.…”

Section: Ancillary Datamentioning

confidence: 99%

Fueling the central engine of radio galaxies

Labiano

García‐Burillo

Combes

et al. 2012

A&A

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Context. There is growing observational evidence of active galactic nuclei (AGN) feedback on the interstellar medium (ISM) of radio-quiet and radio-loud galaxies. While AGN feedback is expected to be more common at high-redshift objects, studying local universe galaxies helps to better characterize the different manifestations of AGN feedback. Aims. Molecular line observations can be used to quantify the mass and energy budget of the gas affected by AGN feedback. We study the emission of molecular gas in 3C 236, a Faranoff-Riley type 2 (FR II) radio source at z∼0.1, and search for the footprints of AGN feedback. The source 3C 236 shows signs of a reactivation of its AGN triggered by a recent minor merger episode. Observations have also previously identified an extreme H i outflow in this source.Methods. The IRAM Plateau de Bure interferometer (PdBI) was used to study the distribution and kinematics of molecular gas in 3C 236 by imaging with high spatial resolution (0.6 ) the emission of the 2-1 line of 12 CO in the nucleus of the galaxy. We searched for outflow signatures in the CO map. We also derived the star-formation rate (SFR) in 3C 236 using data available from the literature at UV, optical, and IR wavelengths, to determine the star-formation efficiency (SFE) of molecular gas. Results. The CO emission in 3C 236 comes from a spatially resolved ∼1.4 (2.6 kpc-) diameter disk characterized by a regular rotating pattern. Within the limits imposed by the sensitivity and velocity coverage of the CO data, we do not detect any outflow signatures in the cold molecular gas. The disk has a cold gas mass M(H 2 ) ∼ 2.1 × 10 9 M . Based on CO we determine a new value for the redshift of the source z CO = 0.09927 ± 0.0002. The similarity between the CO and H i profiles indicates that the deep H i absorption in 3C 236 can be accounted for by a rotating H i structure. This restricts the evidence of H i outflow to only the most extreme velocities. In the light of the new redshift value, the analysis of the ionized gas kinematics reveals a fast (∼1000 km s −1 ) outflow. Outflow signatures in the CO emitting gas, are nevertheless absent in the warm molecular gas emission traced by infrared H 2 lines. The SFE in 3C 236 is consistent with the value measured in normal galaxies, which follow the canonical Kennicutt-Schmidt (KS) relation. This result, confirmed to hold in other young radio sources examined in this work, is in stark contrast with the SFE that is lower by a factor 10-50 that has been claimed to characterize evolved powerful radio galaxies. Conclusions. There are no signs of ongoing AGN feedback to the molecular ISM of 3C 236. The recent reactivation of the AGN in 3C 236 (about 10 5 yr ago) is a likely explanation for the early evolutionary status of its molecular disk.

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“…For 3C 390.3 any polarized flux is undetectable i.e. weak (Taylor et al 2001), as it is in most radio galaxies (Lister & Homan 2005).…”

Section: Discussionmentioning

confidence: 98%

Studies of the Jet in Bl Lacertae. I. Recollimation Shock and Moving Emission Features

Cohen

Meier

Arshakian

et al. 2014

ApJ

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Parsec-scale VLBA images of BL Lac at 15 GHz show that the jet contains a permanent quasi-stationary emission feature 0.26 mas (0.34 pc projected) from the core, along with numerous moving features. In projection, the tracks of the moving features cluster around an axis at position angle -166.6 • that connects the core with the standing feature. The moving features appear to emanate from the standing feature in a manner strikingly similar to the results of numerical 2-D relativistic magneto-hydrodynamic (RMHD) simulations in which moving shocks are generated at a recollimation shock. Because of this, and the close analogy to the jet feature HST-1 in M 87, we identify the standing feature in BL Lac as a recollimation shock. We assume that the magnetic field dominates the dynamics in the jet, and that the field is predominantly toroidal. From this we suggest that the moving features are compressions established by slow and fast mode magneto-acoustic MHD waves. We illustrate the situation with a simple model in which the slowest moving feature is a slow-mode wave, and the fastest feature is a fast-mode wave. In the model the beam has Lorentz factor Γ gal beam ≈ 3.5 in the frame of the host galaxy, and the fast mode wave has Lorentz factor Γ beam Fwave ≈ 1.6 in the frame of the beam. This gives a maximum apparent speed for the moving features, β app = v app /c = 10. In this model the Lorentz factor of the pattern in the galaxy frame is approximately 3 times larger than that of the beam itself.

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Very Long Baseline Array Polarimetry of Three Powerful Radio Galaxy Cores

Cited by 14 publications

References 24 publications

A View through Faraday’s Fog: Parsec‐Scale Rotation Measures in Active Galactic Nuclei

A View through Faraday’s Fog: Parsec‐Scale Rotation Measures in Active Galactic Nuclei

Fueling the central engine of radio galaxies

Studies of the Jet in Bl Lacertae. I. Recollimation Shock and Moving Emission Features

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