scholarly journals Numerical Simulations of Extragalactic Jets in an Inhomogeneous Environment

1996 ◽  
Vol 175 ◽  
pp. 467-468
Author(s):  
Steve Higgins ◽  
TIM O'BRIEN ◽  
James Dunlop
Keyword(s):  
Numerical Simulations ◽  
Three Dimensional ◽  
Second Order ◽  
Godunov Method ◽  
Radio Sources ◽  
Cartesian Coordinates ◽  
Extragalactic Radio Sources ◽  
Extragalactic Jets ◽  
Hydrodynamic Code

We have simulated the passage of an extragalactic jet through a medium containing an ensemble of cool, dense clouds. The hydrodynamic code uses the second-order Godunov method of Falle (Falle 1991, van Leer 1979) in three-dimensional, cartesian coordinates. We have estimated the synchrotron emissivity and used this to produce synthetic radio maps. The results are reminiscent of structures seen in many extragalactic radio sources.

scholarly journals A Numerical Study of Relativistic Jets

1996 ◽  
Vol 175 ◽  
pp. 435-436 ◽  
Author(s):  
J.A. Font ◽  
J.M. Marti ◽  
J.M. Ibáñez ◽  
E. Müller
Keyword(s):  
Numerical Simulations ◽  
Numerical Study ◽  
Supersonic Jets ◽  
Radio Sources ◽  
Riemann Solver ◽  
Relativistic Hydrodynamics ◽  
Two Dimensional ◽  
Relativistic Jets ◽  
Approximate Riemann Solver ◽  
Extragalactic Jets

Numerical simulations of supersonic jets are able to explain the structures observed in many VLA images of radio sources. The improvements achieved in classical simulations (see Hardee, these proceedings) are in contrast with the almost complete lack of relativistic simulations the reason being that numerical difficulties arise from the highly relativistic flows typical of extragalactic jets. For our study, we have developed a two-dimensional code which is based on (i) an explicit conservative differencing of the special relativistic hydrodynamics (SRH) equations and (ii) the use of an approximate Riemann solver (see Martí et al. 1995a,b and references therein).

The Morphology and Surface Brightness of Extragalactic Jets

1983 ◽  
Vol 5 (2) ◽  
pp. 130-135 ◽  
Author(s):  
G. V. Bicknell
Keyword(s):  
Surface Brightness ◽  
Full Width Half Maximum ◽  
Angular Distance ◽  
Radio Sources ◽  
Full Width ◽  
Extragalactic Radio Sources ◽  
The Core ◽  
Extragalactic Jets ◽  
Magnetohydrodynamic Models ◽  
The Relationship

Radio maps of extragalactic radio sources made with the Westerbork, Cambridge and V.L.A. synthesis telescopes have revealed collimated jets extending from the cores to the radio lobes (see Miley 1980 for a review). These observations have provided outstanding support for ‘beam models’ of extragalactic radio sources (Scheuer 1974, Blandford and Rees 1974). Two crucial pieces of information to emerge from high resolution observations are the behaviours of jet full width half maximum (FWHM) and surface brightness with angular distance from the core. Such data have for instance been provided by Formalont et al. (1980) and Bridle et al. (1981) for the jets in 3C-31 and by Willis et al. (1981) and Bridle (1981) for the jets in NGC 315. An important point is that the relationship between jet surface brightness and FWHM is not in general as predicted by simple magnetohydrodynamic models (Bridle 1981).

scholarly journals Fractal Properties of Extragalactic Jets: Evidence of Turbulence?

1996 ◽  
Vol 175 ◽  
pp. 463-464
Author(s):  
G. Bodo ◽  
S. Massaglia ◽  
L. Feretti ◽  
A. Ferrari ◽  
D. Dall'Anese
Keyword(s):  
Direct Evidence ◽  
Theoretical Modelling ◽  
Radio Sources ◽  
Mhd Turbulence ◽  
Important Ingredient ◽  
Extragalactic Radio Sources ◽  
Turbulent Entrainment ◽  
Fractal Properties ◽  
Extragalactic Jets ◽  
Relativistic Particles

Several different properties of extragalactic radio sources have been attributed to the effects of turbulence. The morphological appearance of FRI sources has been often interpreted as the result of turbulent entrainment in subsonic or transonic flows (Bicknell 1984, 1986). Moreover, particle acceleration by MHD turbulence via a second order Fermi process is one of the possible ways for accelerating the synchrotron emitting relativistic particles (see Ferrari, Trussoni & Zaninetti 1979). Turbulence appears therefore as an important ingredient in the theoretical modelling of extragalactic radio sources; however, we do not have, unfortunately, any direct evidence of it.

scholarly journals The different flavors of extragalactic jets: The role of relativistic flow deceleration

2020 ◽  
Vol 642 ◽  
pp. A69 ◽  
Author(s):  
P. Rossi ◽  
G. Bodo ◽  
S. Massaglia ◽  
A. Capetti
Keyword(s):  
Ambient Medium ◽  
Three Dimensional ◽  
Lorentz Factor ◽  
Uniform Density ◽  
Radio Sources ◽  
Extragalactic Jets ◽  
The Galaxy ◽  
Relativistic Flow ◽  
Flow Deceleration

We perform three-dimensional numerical simulations of relativistic (with a Lorentz factor of 10), non-magnetized jets propagating in a uniform density environment in order to study the effect of the entrainment and the consequent deceleration. Our simulations investigate the jet propagation inside the galaxy core, where the deceleration most likely occurs more efficiently. We compare cases with different density and pressure ratios with respect to the ambient medium and find that low density jets are efficiently decelerated and reach a quasi-steady state in which, over a length of 600 jet radii, they slow down from highly relativistic to sub-relativistic velocities. Conversely, denser jets keep highly relativistic velocities over the same length. We discuss these results in relation to the Faranoff Riley (FR) radio source classification. We infer that lower density jets can give rise to FR 0 and FR I radio sources, while higher density jets may be connected to FR II radio sources.

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