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The Jet-disk Boundary Layer in Black Hole Accretion

Wong, George N. and Du, Yufeng and Prather, Ben S. and Gammie, Charles F. (2021) The Jet-disk Boundary Layer in Black Hole Accretion. Astrophysical Journal, 914 (1). Art. No. 55. ISSN 0004-637X.

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Magnetic fields lines are trapped in black hole event horizons by accreting plasma. If the trapped field lines are lightly loaded with plasma, then their motion is controlled by their footpoints on the horizon and thus by the spin of the black hole. In this paper, we investigate the boundary layer between lightly loaded polar field lines and a dense, equatorial accretion flow. We present an analytic model for aligned prograde and retrograde accretion systems and argue that there is significant shear across this jet–disk boundary at most radii for all black hole spins. Specializing to retrograde aligned accretion, where the model predicts the strongest shear, we show numerically that the jet–disk boundary is unstable. The resulting mixing layer episodically loads plasma onto trapped field lines where it is heated, forced to rotate with the hole, and permitted to escape outward into the jet. In one case we follow the mass loading in detail using Lagrangian tracer particles and find a time-averaged mass-loading rate ~0.01 Ṁ.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Wong, George N.0000-0001-6952-2147
Du, Yufeng0000-0003-0510-5170
Prather, Ben S.0000-0002-0393-7734
Gammie, Charles F.0000-0001-7451-8935
Additional Information:© 2021. The American Astronomical Society. Received 2020 November 9; revised 2021 March 16; accepted 2021 April 14; published 2021 June 15. The authors would like to thank the Event Horizon Telescope collaboration, especially Jason Dexter, Ramesh Narayan, and Andrew Chael, as well as Eliot Quataert and Patrick Mullen, for stimulating discussions. The authors also thank Hector Olivares and the anonymous referee for their insightful comments and suggestions that improved the clarity of the manuscript. The authors acknowledge the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for providing HPC resources that have contributed to the research results reported within this paper. This work was supported by NSF grants AST 17-16327 and OISE 17-43747. G.N.W. was supported in part by a Donald C. and F. Shirley Jones Fellowship and a research fellowship from the University of Illinois. B.S.P. was supported in part by the U.S. Department of Energy through Los Alamos National Laboratory. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of the U.S. Department of Energy (Contract No. 89233218CNA000001). C.F.G. was supported in part by a Richard and Margaret Romano Professorial scholarship. Software: NumPy (Oliphant 2015), OpenCV (Bradski 2000), Matplotlib (Hunter 2007).
Funding AgencyGrant Number
Department of Energy (DOE)89233218CNA000001
University of Illinois Urbana-ChampaignUNSPECIFIED
Subject Keywords:Accretion; Magnetohydrodynamics; Plasma astrophysics
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Accretion (14); Magnetohydrodynamics (1964); Plasma astrophysics (1261)
Record Number:CaltechAUTHORS:20210626-183436299
Persistent URL:
Official Citation:George N. Wong et al 2021 ApJ 914 55
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109592
Deposited By: George Porter
Deposited On:28 Jun 2021 15:38
Last Modified:28 Jun 2021 15:38

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