On the Energy Required to Eject Processed Matter from Galaxies

We evaluate the minimum energy input rate that starbursts require for expelling newly processed matter from their host galaxies. Special attention is given to the pressure caused by the environment in which a galaxy is situated, as well as to the intrinsic rotation of the gaseous component. We account for these factors and for a massive dark matter distribution, and we develop a self-consistent solution for the interstellar matter gas distribution. Our results are in excellent agreement with the recent results of Mac Low & Ferrara for galaxies with a flattened, disklike ISM density distribution and a low intergalactic gas pressure ( P IGM / k ≤ 1 cm -3 K). However, our solution also requires a much larger energy input rate threshold when one takes into consideration both a larger intergalactic pressure and the possible existence of a low-density, nonrotating, extended gaseous halo component.