EVOLUTION OF THE STELLAR MASS TULLY-FISHER RELATION IN DISK GALAXY MERGER SIMULATIONS

There is a large observational scatter toward low velocities in the stellar mass Tully-Fisher (TF) relation if disturbed and compact objects are included. However, this scatter can be eliminated if one replaces rotation velocity with S0.5, a quantity that includes a velocity dispersion term added in quadrature with the rotation velocity. In this work, we use a large suite of hydrodynamic N-body galaxy merger simulations to explore a possible mechanism for creating the observed relations. Using mock observations of the simulations, we test for the presence of observational effects and explore the relationship between S0.5 and intrinsic properties of the galaxies. We find that galaxy mergers can explain the scatter in the TF as well as the tight S0.5-stellar mass relation. Furthermore, S0.5 is correlated with the total central mass of a galaxy, including contributions due to dark matter.