Pressure-driven outflow from a dynamo active disc

We present a numerical model of an accretion disc with mean-field dynamo action that develops a fast pressure-driven outflow within a cone near the rotation axis and a slower centrifugally driven outflow in the outer parts of the disc. The fast outflow in the cone is confined by the azimuthal field which is produced by the dynamo in the disc and advected to the disc corona. The fast outflow has low angular momentum and, in the presence of magnetic fields, is hotter and denser than its surroundings. The cone’s half-opening angle is about 30◦ near the disc and decreases slightly with height. The slow outflow transports significant amounts of magnetic energy into the surrounding medium. The general structure of the outflow is similar to that inferred for the BN/KL region in the Orion Nebula.