On the deceleration of Fanaroff–Riley Class I jets: mass loading of magnetized jets by stellar winds. Issue 1 (23rd October 2020)

• Record Type: Journal Article
• Authors: Anglés-Castillo, Andreu; Perucho, Manel; Martí, José María; Laing, Robert A
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 500:Issue 1(2021)
• Page Start: 1512
• Page End: 1530
• Publication Date: 2020-10-23
• Subjects: relativistic processes -- stars: winds, outflows -- galaxies: active -- galaxies: jets; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa3291
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: In this paper, we present steady-state relativistic magnetohydrodynamic simulations that include a mass-load term to study the process of jet deceleration. The mass load mimics the injection of a proton–electron plasma from stellar winds within the host galaxy into initially pair plasma jets, with mean stellar mass-losses ranging from 10 −14 to $10^{-9}\, {\mathrm{M}_\odot \, \mathrm{yr}^{-1}}$ . The spatial jet evolution covers $\sim 500\, {\rm pc}$ from jet injection in the grid at 10 pc from the jet nozzle. Our simulations use a relativistic gas equation of state and a pressure profile for the ambient medium. We compare these simulations with previous dynamical simulations of relativistic, non-magnetized jets. Our results show that toroidal magnetic fields can prevent fast jet expansion and the subsequent embedding of further stars via magnetic tension. In this sense, magnetic fields avoid a runaway deceleration process. Furthermore, when the mass load is large enough to increase the jet density and produce fast, differential jet expansion, the conversion of magnetic energy flux into kinetic energy flux (i.e. magnetic acceleration), helps to delay the deceleration process with respect to non-magnetized jets. We conclude that the typical stellar population in elliptical galaxies cannot explain jet deceleration in classical Fanaroff–Riley type I radio galaxies. However, we observe a significant change in the jet composition, thermodynamical parameters, and energy dissipation along its evolution, even for moderate values of the mass load.