2005/02/28 by Daniel Proga · 5 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1086/431276
to appear in ApJ, revised version with new HD results
arxiv created 2005/04/21 · openalex publication_date 2005/08/03 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We present results from axisymmetric, time-dependent hydrodynamic (HD) and magnetohydrodynamic (MHD) simulations of a gaseous envelope collapsing onto a black hole (BH). We consider gas with such small angular momentum that, after an initial transient, the flow in the HD case accretes directly onto a BH without forming a rotationally supported torus. However, in the MHD case, even with a very weak initial magnetic field, the flow settles into a configuration with four components: (1) an equatorial inflow, (2) a bipolar outflow, (3) polar funnel outflow, and (4) polar funnel inflow. We focus our analysis on the second flow component of the MHD flow, which represents a simple yet robust example of a well-organized inflow/outflow solution to the problem of MHD jet formation. The jet is heavy, highly magnetized, and driven by magnetic and centrifugal forces. A significant fraction of the total energy in the jet is carried out by a large-scale magnetic field. We review previous simulations, in which specific angular momentum was higher than that assumed here, and conclude that our bipolar outflow develops for a wide range of the properties of the flow near the equator and near the poles. Future work on such a simple inflow/outflow solution will help to pinpoint the key elements of real jets/outflows as well as help to interpret much more complex simulations aimed at studying jet formation and the collapse of magnetized envelopes.