Numerical Simulations of Astrophysical Jets from Keplerian Disks with Periodic Ejection

We present 2.5-dimensional time-dependent simulations of nonrelativistic and nonradiative outflows from sinusoidally perturbed Keplerian accretion disks. A sinusoidal perturbation is introduced in the velocity of the gas ejected from the surface of the disk into a cold corona. In the simulations, the disk is a fixed boundary from which the gas is ejected with a pulsed velocity. The maximum value of this velocity is taken to be a thousandth of the local Keplerian disk velocity. It was found that for large periods, the structures in the jet tend to fragment into smaller substructures. For small values of the period, the structures tend to dissipate, while for medium values of the period, they tend to persist. Subject headings: ISM: jets and outflows—galaxies: jets—accretion, accretion disks—MHD.