Evolution of the Stellar Mass Tully-Fisher Relation in Disk Galaxy Merger Simulations

Abstract

There is a large observational scatter toward low velocities in the stellar mass Tully-Fisher relation if disturbed and compact objects are included. However, this scatter can be eliminated if one replaces rotation velocity with ${\mathrm{S}}_{0.5}$, 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 ${\mathrm{S}}_{0.5}$ and intrinsic properties of the galaxies. We find that galaxy mergers can explain the scatter in the TF as well as the tight ${\mathrm{S}}_{0.5}$-stellar mass relation. Furthermore, ${\mathrm{S}}_{0.5}$ is correlated with the total central mass of a galaxy, including contributions due to dark matter.

ApJ accepted