Magnetically Driven Accretion Flows in the Kerr Metric. IV. Dynamical Properties of the Inner Disk

By Julian Krolik, J. Hawley, Shigenobu Hirose. 2004

135 citations recorded by the source corpus.

This paper continues the analysis of a set of general relativistic three-dimensional MHD simulations of accreting tori in the Kerr metric with different black hole spins. We focus on bound matter inside the initial pressure maximum, where the time-averaged motion of gas is inward and an accretion disk forms. We use the flows of mass, angular momentum, and energy in order to understand dynamics in this region. The sharp reduction in accretion rate with increasing black hole spin reported in the first paper of this series is explained by a strongly spin-dependent outward flux of angular momentum conveyed electromagnetically; when a/M ≥ 0.9, this flux can be comparable to the inward angular momentum flux carried by the matter. In all cases, there is outward electromagnetic angular momentum flux throughout the flow; in other words, contrary to the assertions of traditional accretion disk theory, there is in general no "stress edge," no surface within which the stress is zero. The retardation of accretion in the inner disk by electromagnetic torques also alters the radial distribution of surface density, an effect that may have consequences for observable properties, such as Compton reflection. The net accreted angular momentum is sufficiently depressed by electromagnetic effects that in the most rapidly spinning black holes mass growth can lead to spin-down. Spinning black holes also lose energy by Poynting flux; this rate is also a strongly increasing function of black hole spin, rising to ≳10% of the rest-mass accretion rate at very high spin. As the black hole spins faster, the path of the Poynting flux changes from being predominantly within the accretion disk to being predominantly within the funnel outflow.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/4fa82646614cdb85e9b247fd1bccf5243b778f1f

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Citations in the corpus

Total and Jet Blandford-Znajek Power in the Presence of an Accretion Disk (2005, methodology): “The sparse-spin study of Krolik et al. (2005) is in basic agreement with ourhtot.”
Quasars at z = 6: The Survival of the Fittest (2006, background): “…of the disc is of order its radius and can also changed by magnetic effects which allow energy release from within the innermost stable orbit (e.g., Krolik et al. 2005) mining the maximum radiative efficiency (or spin, using the standard conversion) which allows the growth of MBHs into SMBHs…”
Hot Accretion Flows Around Black Holes (2014, methodology): “Representative results from 3D GRMHD simulations can be found in the series of early papers by De Villiers and collaborators (De Villiers et al. 2003, 2005; Hirose et al. 2004; Krolik et al. 2005) and Gammie and collaborators (Gammie et al. 2004, McKinney & Gammie 2004, McKinney 2006).”
Understanding X‐ray reflection emissivity profiles in AGN: locating the X‐ray source (2012, methodology): “For completeness, we include here the derivation of the tetrad basis vectors defining the local rest frame of a source orbiting the rotation axis of the black hole in the Kerr spacetime (see also, e.g., Krolik et al. 2005; Beckwith et al. 2008).”
Constraining Black Hole Spin via X-Ray Spectroscopy (2006, background): “…within the radius of marginal stability, as well as angular momentum lost from the rotating black hole itself via Blandford-ZjanekYlike mechanisms (Blandford & Znajek 1977), may lead to a rather lower equilibrium spin (e.g., see the general relativistic MHD simulations of Krolik et al. 2005).”
Three-Dimensional Simulations of Magnetized Thin Accretion Disks around Black Holes: Stress in the Plunging Region (2008, methodology): “Numerical MHD simulations by Krolik & Hawley (2002) using a pseudo-Newtonian potential, and by Krolik et al. (2005) using a GRMHD code, indicated that magnetic torques are indeed important inside the ISCO.”
Mechanical feedback from active galactic nuclei in galaxies, groups and clusters (2012, methodology): “The jetted outflow is coupled to the black hole’s rotational energy by magnetic fields supplied by and anchored to an accretion disk (Meier 1999, Krolik et al 2005, Beckwith et al 2009, Krolik and Hawley 2010).”
The X-Ray-to-Optical Properties of Optically Selected Active Galaxies over Wide Luminosity and Redshift Ranges (2006, methodology): “…accreting SMBHs from first principles using relativistic magneto-hydrodynamic simulations (e.g., Hawley et al. 1995; De Villiers & Hawley 2003; Krolik et al. 2005) will be able to explain the observed αOX - l2500Å relation, but to our knowledge these simulations have not yet found a physical…”
A systematic search for changing-look quasars in SDSS (2015, background): “The value of tinfl may be a several times shorter based on magneto-hydrodynamical simulations (e.g., Krolik et al. 2005), but this is still too long to explain the continuum variability of all sources presented MNRAS 000, 1–17 (2015) here (see the Appendix for the individual physical parameters and…”
Simulations of magnetized discs around black holes: Effects of black hole spin, disc thickness and magnetic field geometry (2010, background): “In these studies, a plot of the radial profile of the normalized stress within the ISCO appears to indicate a significant deviation from the NT thin disc theory (Krolik et al. 2005; Beckwith et al. 2008b), and it was thus expected that much thinner discs might also deviate significantly from NT.”