A common approach to interpret the `jet phenomenon' observed in active galactic nuclei and young stellar objects is via magnetohydrodynamic models of collimated outflows magnetically driven from quasi-Keplerian accretion discs in the proximity of a central gravitational attractor. In this study we present a series of time-dependent axisymmetric numerical simulations of a jet-launching accretion disc, where the outflow and the disc itself are treated consistently. In particular, the issue of thermal effects due to anomalous transport coefficients is being addressed. When the radiative losses of the accretion disc cannot perfectly balance Ohmic and viscous heating, the latter can severely influence the mass loading process. Since the ejection rates determine to a great extent the dynamics of the outflowing plasma, disc thermodynamics should not be neglected. We investigate numerically the impact of heating-cooling effects in both outflow dynamics and accretion disc structure. A relationship is established between heating and various important parameters of the outflow (magnetic lever arm, ejection efficiency, mass flux, etc.) that is briefly discussed in connection with observational data.

Effects of entropy generation in jet-launching discs

MIGNONE, ANDREA;MASSAGLIA, Silvano
2013-01-01

Abstract

A common approach to interpret the `jet phenomenon' observed in active galactic nuclei and young stellar objects is via magnetohydrodynamic models of collimated outflows magnetically driven from quasi-Keplerian accretion discs in the proximity of a central gravitational attractor. In this study we present a series of time-dependent axisymmetric numerical simulations of a jet-launching accretion disc, where the outflow and the disc itself are treated consistently. In particular, the issue of thermal effects due to anomalous transport coefficients is being addressed. When the radiative losses of the accretion disc cannot perfectly balance Ohmic and viscous heating, the latter can severely influence the mass loading process. Since the ejection rates determine to a great extent the dynamics of the outflowing plasma, disc thermodynamics should not be neglected. We investigate numerically the impact of heating-cooling effects in both outflow dynamics and accretion disc structure. A relationship is established between heating and various important parameters of the outflow (magnetic lever arm, ejection efficiency, mass flux, etc.) that is briefly discussed in connection with observational data.
428
3151
3163
accretion; accretion discs; MHD; methods: numerical; ISM: jets and outflows
Tzeferacos, P.; Ferrari, A.; Mignone, A.; Zanni, C.; Bodo, G.; Massaglia, S.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/126960
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