Star Formation, Supernova Feedback, and the Angular Momentum Problem in Numerical Cold Dark Matter Cosmogony: Halfway There?

We present a smoothed particle hydrodynamic simulation that reproduces a galaxy that is a moderate facsimile of those observed. The primary failing point of previous simulations of disk formation, namely, excessive transport of angular momentum from gas to dark matter, is ameliorated by the inclusion of a supernova feedback algorithm that allows energy to persist in the model interstellar medium for a period corresponding to the lifetime of stellar associations. The inclusion of feedback leads to a disk at a redshift z = 0.52, with a specific angular momentum content within 10% of the value required to fit observations. An exponential fit to the disk baryon surface density gives a scale length within 17% of the theoretical value. Runs without feedback, with or without star formation, exhibit the drastic angular momentum transport observed elsewhere.