The radio morphology of 3C 120 on scales from 0.5 parsecs to 400 kiloparsecs

Walker, R. C.; Benson, John M.; Unwin, S. C.

doi:10.1086/165225

Cited by 117 publications

(85 citation statements)

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“…Assuming that the longitudinal velocity (and its shear) varies along z. only insignificantly (a supersonic jet), the conservation of mass implies that ρ oc Ä" 2 . Therefore, we obtain the relationship Β oc R~x which agrees with the observations of Walker et al (1987). Within the framework of the present interpretation, this scaling applies to the total regular magnetic field.…”

supporting

confidence: 89%

Hydromagnetic Dynamo in Astrophysical Jets

Shukurov

Sokoloff

1993

Symp. - Int. Astron. Union

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A b s t r a c t . The origin of a regular magnetic field in astrophysical jets is discussed. It is shown that jet plasma flow can generate a magnetic field provided the streamlines are helical. The dynamo of this type, known as the screw dynamo, generates magnetic fields with the dominant azimuthal wave number m = 1 whose field lines also have a helical shape. The field concentrates into a relatively thin cylindrical shell and its configuration is favorable for the collimation and confinement of the jet plasma.K e y words: The screw dynamo -Astrophysical jets Long, thin, well-collimated jets are a widespread companion of energetic activity in radio galaxies and young stars (see, e.g., the reviews of Begelman et al., Lada, 1985), and even in the Galactic center region (Mirabel et ai, 1992). Polarization observations of the synchrotron emission of extragalactic jets indicate the presence of magnetic fields of a few /iG strength at the kiloparsec scale. A high polarization of the synchrotron emission indicates a rather high degree of ordering of the magnetic field, although purely random two-dimensional magnetic field configurations can also produce polarized emission (Laing, 1981). It seems only reasonable to conclude that magnetic fields in the jets contain both regular and random components, as do the fields in all other astronomical objects. In many cases, polarization observations are compatible with a helical shape for the field lines of the ordered field.In contrast to the rather detailed knowledge of the magnetic field morphology in extragalactic jets, very little is known about the plasma velocity patterns. This is due to the fact that extragalactic jets emit mainly a continuous, synchrotron emission, so that the classical method of the observational study of velocity fields based on the Doppler shifts of spectral lines does not work. As a result, our knowledge of the jet velocity fields is only rudimentary. However, there is an indirect evidence of a helical shape for the streamlines in the jets of quasars and BL Lac objects as discussed by Camenzind and Krockenberger (1992). The helical shape of both the streamlines and the magnetic lines is also a property of many self-similar MHD jet models.The observational situation with stellar jets is quite the opposite. They contain rather dense thermal plasma, so that their velocity fields can be studied, at least in principle, by conventional methods of astronomy. Up to now, observational attempts have focused on the longitudinal velocity in stellar jets but, undoubtedly, information on the transverse velocity components and the velocity profiles across the jet will follow. However, up to now there is hardly any information about magnetic fields in stellar bipolar outflows, even though magnetic field is believed to play an important role in the formation, collimation and confinement of both extragalactic and stellar jets (see Begelman et al., 1984;Camenzind, 1990). As long as we might believe that the mechanisms of acceleration and collimation of the jet

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supporting

confidence: 89%

Hydromagnetic Dynamo in Astrophysical Jets

Shukurov

Sokoloff

1993

Symp. - Int. Astron. Union

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“…There are of course numerous examples of large scale bending (e.g. 3C 120: Walker, Benson & Unwin 1987) and discrete deflections (e.g. 3C 390.…”

Section: Forward and Reverse Shocksmentioning

confidence: 99%

X-Ray Emission from Extragalactic Jets

Harris

Krawczynski

2006

Annu. Rev. Astron. Astrophys.

256

254

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This review focuses on the X-ray emission processes of extra-galactic jets on scales resolvable by the sub arcsec resolution of the Chandra X-ray Observatory. It is divided into 4 parts. The introductory chapter reviews the classical problems for jets, as well as those associated directly with the X-ray emission. Throughout this section, we deal with the dualisms of low powered radio sources versus high powered radio galaxies and quasars; synchrotron models versus inverse Compton models; and the distinction between the relativistic plasma responsible for the received radiation and the medium responsible for the transport of energy down the jet. The second part collects the observational and inferred parameters for the currently detected X-ray jets and attempts to put their relative sizes and luminosities in perspective. In part 3, we first give the relevant radio and optical jet characteristics, and then examine the details of the X-ray data and how they can be related to various jet attributes. The last section is devoted to a critique of the two non-thermal emission processes and to prospects for progress in our understanding of jets.

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“…The Fanaroff-Riley Class I radio galaxy (Walker et al 1987) 3C 120 (z = 0.033) is optically classified as a broad-line radio galaxy (BLRG). Its broadband spectrum is dominated by the non-thermal jet emission along with a thermal disk component, hence this BLRG is an ideal source to study the jet-disk connection.…”

Section: Introductionmentioning

confidence: 99%

Six Years of Fermi-Lat and Multi-Wavelength Monitoring of the Broad-Line Radio Galaxy 3c 120: Jet Dissipation at Sub-Parsec Scales From the Central Engine

Tanaka

Doi

Inoue

et al. 2015

ApJ

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We present multi-wavelength monitoring results for the broad-line radio galaxy 3C 120 in the MeV/GeV, submillimeter, and 43 GHz bands over 6 yr. Over the past 2 yr, the Fermi-Large Area Telescope sporadically detected 3C 120 with high significance and the 230 GHz data also suggest an enhanced activity of the source. After the MeV/GeV detection from 3C 120 in MJD 56240-56300, 43 GHz Very Long Baseline Array (VLBA) monitoring revealed a brightening of the radio core, followed by the ejection of a superluminal knot. Since we observed the γ-ray and VLBA phenomena in temporal proximity to each other, it is naturally assumed that they are physically connected. This assumption was further supported by the subsequent observation that the 43 GHz core brightened again after a γ-ray flare occurred around MJD 56560. We can then infer that the MeV/GeV emission took place inside an unresolved 43 GHz core of 3C 120 and that the jet dissipation occurred at sub-parsec distances from the central black hole (BH), if we take the distance of the 43 GHz core from the central BH as ∼0.5 pc, as previously estimated from the time lag between X-ray dips and knot ejections. Based on our constraints on the relative locations of the emission regions and energetic arguments, we conclude that the γ rays are more favorably produced via the synchrotron self-Compton process, rather than inverse Compton scattering of external photons coming from the broad line region or hot dusty torus. We also derived the electron distribution and magnetic field by modeling the simultaneous broadband spectrum.

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The radio morphology of 3C 120 on scales from 0.5 parsecs to 400 kiloparsecs

Cited by 117 publications

References 0 publications

Hydromagnetic Dynamo in Astrophysical Jets

Hydromagnetic Dynamo in Astrophysical Jets

X-Ray Emission from Extragalactic Jets

Six Years of Fermi-Lat and Multi-Wavelength Monitoring of the Broad-Line Radio Galaxy 3c 120: Jet Dissipation at Sub-Parsec Scales From the Central Engine

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