The Rate of Star Formation in Galactic Disks

Abstract

A simple prescription is -presented for the rate of star formation in normal galactic disks, motivated by semi-phenomenological dynamical arguments. When energy input into the interstellar medium is included as a feedback mechanism to couple the star formation driven by disk instabilities with gaseous dissipation, one can obtain expressions for both disk surface density and the Tully-Fisher relation in good accord with observation. One plausibly expects variations at a level of order ~10% in the Tully-Fisher zero-point due to age and/or star formation history that may be correlated over supercluster scales. I also show that there is a limiting rate of star formation, maintained by the porosity of the hot component of the multiphase interstellar medium, that can be interpreted as arising in starbursts that are triggered by galaxy mergers. The predicted star formation rate is found to be sensitive to the ambient pressure and results in enhanced star formation in galaxies that are undergoing first infall at cluster peripheries (out to ~10h-l Mpc from an Abell cluster).