Feedback in simulations of disc-galaxy major mergers

Using hydrodynamic simulations of disk-galaxy major mergers we investigate the starformation history and remnant properties when various parameterizations of a simple stellar feedback model are implemented. The simulations include radiative cooling, a density-dependent star-formation recipe and a model for feedback from massive stars. The feedback model stores supernova feedback energy within individual gas particles and dissipates this energy on a time-scale specified by two free parameters; τfb, which sets the dissipative timescale, and n, which sets the effective equation of state in star-forming regions. Via this model, feedback energy can provide pressure support to regions of gas that are thermally cold. Using a self-consistent disk galaxy, modeled after a local Sbc spiral, in both isolated and major-merger simulations, we investigate parameterizations of the feedback model that are selected with respect to the quiescent disk stability. These models produce a range of star formation histories for disks evolved in isolation, or during a major merger, yet all are consistent with the star formation relation found by Kennicutt (1998). We suggest that this result