MHD simulations of jet acceleration from Keplerian accretion disks - The effects of disk resistivity

By C. Zanni, A. Ferrari, R. Rosner, Gianluigi Bodo, Silvano Massaglia. 2007

175 citations recorded by the source corpus.

Context: Accretion disks and astrophysical jets are used to model many active astrophysical objects, such as young stars, relativistic stars, and active galactic nuclei. However, existing proposals for how these structures may transfer angular momentum and energy from disks to jets through viscous or magnetic torques do not yet provide a full understanding of the physical mechanisms involved. Thus, global stationary solutions have not explained the stability of these structures; and global numerical simulations that include both the disk and jet physics have so far been limited to relatively short time scales and narrow (and possibly astrophysically unlikely) ranges of viscosity and resistivity parameters that may be crucial to defining the coupling of the inflow-outflow dynamics. Aims: We present self-consistent, time-dependent simulations of supersonic jets launched from magnetized accretion disks, using high-resolution numerical techniques. In particular we study the effects of the disk's magnetic resistivity, parametrized through an α-prescription, in determining the properties of the inflow-outflow system. Moreover we analyze under which conditions steady state solutions of the type proposed in the self-similar models of Blandford & Payne can be reached and maintained in a self-consistent nonlinear stage. Methods: We used the resistive MHD FLASH code with adaptive mesh refinement (AMR), allowing us to follow the evolution of the structure on a long enough time scale to reach steady state. A detailed analysis of the initial configuration state is given. Results: We obtain the expected solutions within the axisymmetric (2.5 D) limit. Assuming a magnetic field around equipartition with the thermal pressure of the disk, we show how the characteristics of the disk-jet system, such as the ejection efficiency and the energetics, are affected by the anomalous resistivity acting inside the disk.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2534b56e0b5faf86940382cd30aae0eccef740f7

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Citations in the corpus

WIND-DRIVEN ACCRETION IN PROTOPLANETARY DISKS. I. SUPPRESSION OF THE MAGNETOROTATIONAL INSTABILITY AND LAUNCHING OF THE MAGNETOCENTRIFUGAL WIND (2013, background): “…large diffusion (that is unjustified) to prevent rapid magnetic flux accumulation near the central object as mass accretes (Kato et al. 2002; Casse & Keppens 2002, 2004), and the resulting wind properties largely depend on the prescribed resistivity profile in the disk (Zanni et al. 2007).”
LOCAL STUDY OF ACCRETION DISKS WITH A STRONG VERTICAL MAGNETIC FIELD: MAGNETOROTATIONAL INSTABILITY AND DISK OUTFLOW (2012, background): “Numerous global simulations have studied launching of disk wind in the context of protostellar disks (e.g., Kato et al. 2002; Casse & Keppens 2002; Zanni et al. 2007)).”
Global Simulations of the Inner Regions of Protoplanetary Disks with Comprehensive Disk Microphysics (2017, methodology): “…(e.g., Blandford & Payne 1982; Li 1995; Ferreira 1997) to local solutions that match them (e.g., Wardle & Koenigl 1993; Königl et al. 2010; Salmeron et al. 2011), as well as global simulations (e.g., Krasnopolsky et al. 1999; Pudritz et al. 2006; Zanni et al. 2007; Tzeferacos et al. 2009).”