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The physical structure of radio galaxies explored with three-dimensional simulations

Donohoe, Justin, Smith, Michael D. (2016) The physical structure of radio galaxies explored with three-dimensional simulations. Monthly Notices of the Royal Astronomical Society, 458 (1). pp. 558-574. ISSN 0035-8711. (doi:10.1093/mnras/stw335) (KAR id:60000)

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We present a large systematic study of hydrodynamic simulations of supersonic adiabatic jets in three dimensions to provide a definitive set of results on exploring jet density, Mach number and precession angle as variables. We restrict the set-up to non-relativistic pressure-equilibrium flows into a homogeneous environment. We first focus on the distribution and evolution of physical parameters associated with radio galaxies. We find that the jet density has limited influence on the structure for a given jet Mach number. The speed of advance varies by a small factor for jet densities between 0.1 and 0.0001 of the ambient density while the cocoon and cavity evolution change from narrow pressure balanced to wide overpressure as the ratio falls. We also find that the fraction of energy transferred to the ambient medium increases with decreasing jet–ambient density ratio, reaching ≈80 per cent. This energy is predominantly in thermal energy with almost all the remainder in ambient kinetic form. The total energy remaining in the lobe is typically under 5 per cent. We find that radio galaxies with wide transverse cocoons can be generated through slow precession at low Mach numbers. We explore a slow precession model in which the jet direction changes very slowly relative to the jet flow dynamical time. This reveals two separated bow shocks propagating into the ambient medium, one associated with the entire lobe expansion and the other with the immediate impact zone. The lobes generated are generally consistent with observations, displaying straight jets but asymmetric lobes.

Item Type: Article
DOI/Identification number: 10.1093/mnras/stw335
Uncontrolled keywords: hydrodynamics
Subjects: Q Science > QB Astronomy
Divisions: Divisions > Division of Natural Sciences > School of Physical Sciences
Depositing User: Michael Smith
Date Deposited: 23 Jan 2017 09:53 UTC
Last Modified: 16 Feb 2021 13:41 UTC
Resource URI: (The current URI for this page, for reference purposes)
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