On MHD jet production in the collapsing and rotating envelope

We present results from axisymmetric, time-dependent magnetohydrodynamical (MHD) simulations of a gaseous envelope collapsing onto a black hole (BH). We consider gas with so small angular momentum that, if not for the effects of MHD, the flow would accrete directly onto a BH. We find that after an initial transient, the flow settles into a configuration with four components: (i) a radial equatorial inflow, (ii) a bipolar outflow, (iii) polar funnel outflow, and (iv) polar funnel inflow. We focus our analysis on the second flow component which is 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, where 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 collapse of magnetized envelopes. Subject headings: accretion, accretion disks – methods: numerical – MHD – stars: winds, outflows