CONSERVATIVE GRMHD SIMULATIONS OF MODERATELY THIN, TILTED ACCRETION DISKS

Author(s)

Teixeira, Danilo Morales ^[1] ; Fragile, P. Chris ^[2] ; Zhuravlev, Viacheslav V. ^[3] ; Ivanov, Pavel B. ^[4]

Affiliation

^[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508090 Sao Paulo - Brazil

^[2] Coll Charleston, Dept Phys & Astron, Charleston, SC 29424 - USA

^[3] Moscow MV Lomonosov State Univ, Sternberg Astron Inst, Moscow 119992 - Russia

^[4] PN Lebedev Phys Inst, Ctr Astro Space, Moscow 117810 - Russia

• Document type: Journal article
• Source: ASTROPHYSICAL JOURNAL; v. 796, n. 2 DEC 1 2014.
• Web of Science Citations: 23

Abstract

This paper presents our latest numerical simulations of accretion disks that are misaligned with respect to the rotation axis of a Kerr black hole. In this work, we use a new, fully conservative version of the Cosmos++ general relativistic magnetohydrodynamics (GRMHD) code, coupled with an ad hoc cooling function designed to control the thickness of the disk. Together these allow us to simulate the thinnest tilted accretion disks ever using a GRMHD code. In this way, we are able to probe the regime where the dimensionless stress and scale height of the disk become comparable. We present results for both prograde and retrograde cases. The simulated prograde tilted disk shows no sign of Bardeen-Petterson alignment even in the innermost parts of the disk. The simulated retrograde tilted disk, however, does show modest alignment. The implication of these results is that the parameter space associated with Bardeen-Petterson alignment for prograde disks may be rather small, only including very thin disks. Unlike our previous work, we find no evidence for standing shocks in our simulated tilted disks. We ascribe this to the black hole spin, tilt angle, and disk scale height all being small in these simulations. We also add to the growing body of literature pointing out that the turbulence driven by the magnetorotational instability in global simulations of accretion disks is not isotropic. Finally, we provide a comparison between our moderately thin, untilted reference simulation and other numerical simulations of thin disks in the literature. (AU)

• FAPESP's process: 09/54006-4 - A computer cluster for the Astronomy Department of the University of São Paulo Institute of Astronomy, Geophysics and Atmospheric Sciences and for the Cruzeiro do Sul University Astrophysics Center
• Grantee: Elisabete Maria de Gouveia Dal Pino
• Support Opportunities: Multi-user Equipment Program