Instabilities in Three‐dimensional Simulations of Astrophysical Jets Crossing Tilted Interfaces

Hooda, Jagbir S.; Wiita, Paul J.

doi:10.1086/305099

Cited by 17 publications

(9 citation statements)

References 38 publications

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“…The substantial difference between the two estimates was taken by Scheuer as evidence for a rapid 'backflow' of the relativistic plasma within the lobes, which is indeed expected if the jet material is much less dense than the ambient plasma. Such strong backflows are clearly observed in many numerical simulations of jet propagation (e.g., Norman 1996;Hooda & Wiita 1998).…”

Section: Further Constraining the Hot-spot Speeds By The Jet-sidednessmentioning

confidence: 80%

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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Section: Further Constraining the Hot-spot Speeds By The Jet-sidednessmentioning

confidence: 80%

Unified Schemes for Extragalactic Radio Sources

Gopal-Krishna

1996

Extragalactic Radio Sources

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“…For our calculations we choose θ = 0.1 rad, which is certainly justified as appropriate for the inner jet regions, particularly since it is now recognized that the jet's thrust acts on a larger area than the instantaneous hot spot (e.g., Scheuer's 1982 'dentist-drill', as supported by many threedimensional numerical simulations: Norman 1996; Clarke 1996; Hooda & Wiita 1998). Following Bicknell (1995), we further assume that the X-ray emitting ISM gas temperature is tied to the central stellar velocity dispersion, σ, via, kT = 2.2µm p σ 2 /δ, which is Fall's (1987) relation between circular velocity and σ.…”

Section: The Modelmentioning

confidence: 99%

The Fanaroff-Riley transition and the optical luminosity of the host elliptical galaxy

Gopal-Krishna¹,

Wiita²

2001

A&A

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Abstract.We show that a model for radio source dynamics we had earlier proposed can readily reproduce the relationship between the radio power division separating the two Fanaroff-Riley classes of extragalactic radio sources and the optical luminosity of the host galaxy, as found by Owen & Ledlow (1994). In our scenario, when less powerful jets eventually slow down to the point that the advance of the working surface (i.e., hotspot) becomes subsonic with respect to the external gas, the jet's collimation is severely weakened. This criterion distinguishes the powerful and well collimated FR II sources from the weaker sources producing the less collimated FR I type morphologies.

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“…The most novel assumption is the transition from low to high density across a contact interface (across which the pressure is necessarily constant), which is different from the work done by Hooda & Wiita (1998) where they used a classical code with a density decrease across the contact, and also different from the study by Loken et al (1993), where they used a classical code to look into jet propagation through a pressure wall. We explored the influence of a sudden density jump in ISM on jet propagation, stability, and formation of the bow shock.…”

Section: Introductionmentioning

confidence: 99%

Faranoff-Riley type I jet deceleration at density discontinuities

Méliani

Keppens

Giacomazzo

2008

A&A

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Aims. We propose a model that could explain the sudden jet deceleration in active galactic nuclei, thereby invoking density discontinuities. Motivated particularly by recent indications from HYbrid MOrphology Radio Sources (HYMORS) that Fanaroff-Riley classification is induced in some cases by variations in the density of the external medium. We explore how one-sided jet deceleration and a transition to FR I type can occur in HYMORS, which start as FR II (and remain so on the other side). Methods. We implemented the Synge-type equation of state introduced in the general polytropic case by Meliani et al. (2004, A&A, 425, 773) into the relativistic hydrodynamic grid-adaptive AMRVAC code. To demonstrate its accuracy, we set up various test problems in an appendix, which we compare to exact solutions that we calculate as well. We use the code to analyse the deceleration of jets in FR II/FR I radio galaxies, following them at high resolution across several hundred jet beam radii. Results. We present results for 10 model computations that vary the inlet Lorentz factor from 10 to 20, include uniform or decreasing density profiles, and allow for cylindrical versus conical jet models. As long as the jet propagates through uniform media, we find that the density contrast sets most of the propagation characteristics, fully consistent with previous modelling efforts. When the jet runs into a denser medium, we find a clear distinction in the decelaration of high-energy jets depending on the encountered density jump. For fairly high-density contrast, the jet becomes destabilised and compressed, decelerates strongly (up to subrelativistic speeds), and can form knots. If the density contrast is too weak, the high-energy jets continue with FR II characteristics. The trend is similar for the low-energy jet models, which start as underdense jets from the outset, and decelerate by entrainment into the lower region as well. We point out differences that are found between cylindrical and conical jet models, together with dynamical details like the Richtmyer-Meshkov instabilities developing at the original contact interface.

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Instabilities in Three‐dimensional Simulations of Astrophysical Jets Crossing Tilted Interfaces

Cited by 17 publications

References 38 publications

Unified Schemes for Extragalactic Radio Sources

Unified Schemes for Extragalactic Radio Sources

The Fanaroff-Riley transition and the optical luminosity of the host elliptical galaxy

Faranoff-Riley type I jet deceleration at density discontinuities

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