2008/03/14 by Agnieszka Janiuk, Daniel Proga, Ryuichi Kurosawa
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1086/588375
22 pages, 16 figures; Accepted to ApJ; higher resolution version of the paper can be downloaded from http://users.camk.edu.pl/agnes/preprints/tilted_torus.pdf
arxiv created 2008/03/14 · openalex publication_date 2008/07/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We report on the fourth phase of our study of slightly rotating accretion flows onto black holes. The main new element of this study is that we used fully three dimensional (3D) numerical simulations. We consider the hydrodynamics of inviscid accretion flows, assuming a spherically symmetric density distribution at the outer boundary, but braking the flow symmetry by introducing a small, latitude-dependent angular momentum. We also consider cases in which angular momentum at large radii is latitude- and azimuth-dependent. For the latitude-dependent angular momentum, 3D simulations confirm axisymmetric results: the material that has too much angular momentum to be accreted forms a thick torus near the equator. Consequently, accretion proceeds only through the polar funnel, and the mass accretion rate through the funnel is constrained by the size and shape of the torus, not by the outer conditions. In 3D simulations, we find that the torus precesses even for axisymmetric conditions at large radii. For the latitude and azimuth-dependent angular momentum, the nonrotating gas near the equator can also significantly affect the evolution of the rotating gas. In particular, it may prevent the formation of a proper torus (i.e., its closing, in the azimuthal direction). In such models, the mass accretion rate is only slightly less than the corresponding Bondi rate.