Alternating-side ejection in extragalactic radio sources

Rudnick, Lawrence; Edgar, B. K.

doi:10.1086/161866

Cited by 37 publications

(8 citation statements)

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“…Firstly, its mere existence shows that the M 87 jet is two-sided as it is launched, which is commonly assumed, but rarely proven in superluminal sources. This provides evidence against flip-flop models (e.g., Rudnick & Edgar 1984) where the jet is one-sided at any given time. Secondly, the ratio of brightness of the jet and counter-jet, if it is assumed to be the result of Doppler boosting, gives a measure of the jet speed.…”

Section: The Counter-jetmentioning

confidence: 81%

The Structure and Dynamics of the Subparsec Jet in M87 Based on 50 VLBA Observations over 17 Years at 43 GHz

Walker

Hardee

Davies

et al. 2018

ApJ

329

324

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The central radio source in M 87 provides the best opportunity to study jet formation because it has a large angular size for the gravitational radius of the black hole and has a bright jet that is well resolved by VLBI observations. We present intensive monitoring observations from 2007 and 2008, plus roughly annual observations that span 17 years, all made with the the Very Long Baseline Array at 43 GHz with a resolution of about 30 by 60 R S . Our high-dynamic-range images clearly show the wide-opening-angle structure and the counter-jet. The jet and counter-jet are nearly symmetric in the inner 1.5 milli-arcseconds (mas; 0.12 pc in projection) with both being edge brightened. Both show deviations from parabolic shape in the form of an initial rapid expansion and subsequent contraction followed by further rapid expansion and, beyond the visible counter-jet, subsequent collimation. Proper motions and counter-jet/jet intensity ratios both indicate acceleration from apparent speeds of 0.5c to 2c in the inner ∼2 mas and suggest a helical flow. The jet displays a sideways shift with an approximately 8 to 10 year quasi-periodicity. The shift propagates outwards non-ballistically and significantly more slowly than the flow speed revealed by the fastest moving components. Polarization data show a systematic structure with magnetic field vectors that suggest a toroidal field close to the core.

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Section: The Counter-jetmentioning

confidence: 81%

The Structure and Dynamics of the Subparsec Jet in M87 Based on 50 VLBA Observations over 17 Years at 43 GHz

Walker

Hardee

Davies

et al. 2018

ApJ

329

324

View full text Add to dashboard Cite

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“…In either case, the dominance of intrinsic asymmetry (Q int = 1) excludes the possibility of applying the elegant formulation of Banhatti (1980) to determine the velocity distribution analytically from the observed Q-distribution. It may also be mentioned that several researchers (e.g., Ryś 1994; LHG) have attempted to model the Q-distribution within the framework of the alternate ejection hypothesis proposed by Rudnick & Edgar (1984) (see also, Willis, Wilson & Strom 1978;Wiita & Siah 1981;Komberg 1994), though differing conclusions have been reached ( §7.2). The first treatment of the lobe expansion which treated the dynamics of a relativistic hot-spot was given by Gopal-Krishna, Wiita & Saripalli (1989).…”

Section: Historical Perspectivementioning

confidence: 99%

Unified Schemes for Extragalactic Radio Sources

Gopal-Krishna

1996

Extragalactic Radio Sources

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My own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose -J.B.S. Haldane OverviewThis review aims to provide the background and current perspective of some of the striking asymmetries exhibited by extragalactic double-lobed radio sources, paying special attention to the reported interrelationships among some of them. The asymmetries addressed here are related not only to the jets, and we particularly aim to highlight some less discussed aspects pertaining to the radio lobes and hot-spots for which any relativistic beaming effects are milder than those imposed on the jets. Various attributes of these features, such as their geometry, intensity, spectrum, and polarization provide important underpinnings to models of radio galaxies and quasars, as well as to theories that attempt to unify them. These constraints can be further sharpened by exploiting the more recently discovered asymmetry properties of the extended optical emission-line regions (EELR) associated with powerful radio sources, including the giant halos of Lyman-α emission associated with them. We suggest that highly extended disks of dusty gaseous material, which could also be parts of cosmic filaments, around the host galaxies of radio sources may hold the key to understanding some important types of asymmetries, namely, the correlated radio-optical asymmetry and perhaps also the depolarization asymmetry of the twin radio lobes.We also discuss the nature and possible implications of the extreme type of asymmetry witnessed in the enigmatic quasar 3C273, whose entire radio emission is observed on just one side of the nucleus. In this context, theoretical scenarios for the production of one-sided jets are also briefly recounted. Taking a clue from the observed one-sidedness of the extended radio jets even in 'weak-headedquasars', we also propose a scenario for the late evolutionary stage of double radio sources. We end by providing a list of key questions relating to radio source asymmetries which still require final answers.

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“…These include the possibilities that (i) the jets are intrinsically symmetric but appear one-sided or highly asymmetric because the brightness of the receding one is diminished due to bulk relativistic motion while the approaching jet is boosted for the same reason (Rees 1978;Blandford & Königl 1979;Scheuer & Readhead 1979); (ii) the active beam on the counter-jet side has a low synchrotron emissivity and (iii) the energy supply is intrinsically asymmetric, but supplies energy alternately on opposite sides of the nucleus (cf. Saikia & Wiita 1982;Rudnick & Edgar 1984). …”

Section: Introductionmentioning

confidence: 99%

B1524-136: A CSS quasar with two-sided radio jets

Mantovani

Saikia

Bondì

et al. 2002

A&A

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Abstract. We present MERLIN, global VLBI and VLBA observations of the high-luminosity, compact steepspectrum quasar B1524−136 at cm wavelengths. These observations reveal well-defined radio jets on both sides of the active nucleus, a situation which is almost unique amongst high-luminosity radio quasars. However, the radio jets on opposite sides are very dissimilar, and the overall radio structure appears highly distorted. We discuss possible implications of these observations.

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Alternating-side ejection in extragalactic radio sources

Cited by 37 publications

References 0 publications

The Structure and Dynamics of the Subparsec Jet in M87 Based on 50 VLBA Observations over 17 Years at 43 GHz

The Structure and Dynamics of the Subparsec Jet in M87 Based on 50 VLBA Observations over 17 Years at 43 GHz

Unified Schemes for Extragalactic Radio Sources

B1524-136: A CSS quasar with two-sided radio jets

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