The stellar mass of star forming galaxies is thought to increase in a quasi-steady state, where the rate depends on the gas fraction and star formation efficiency, which evolve with redshift. Galaxy mergers can lead to more rapid growth while active galactic nuclei have been argued to play an important role in halting star formation. These processes are tied together through the multi-phase interstellar medium.
I will discuss programs exploring so-called "dense gas" tracers and the behavior of starbursts in merging dwarf galaxies. I will also describe a theoretical/modeling program to age-date galaxy mergers and constrain the initial conditions of their encounters. This use of multiwavelength tracers and hydrodynamic simulations probes galaxy evolution along axes of nuclear activity, redshift, gas fraction, and metallicity. From these studies I will show new results on identification of heavily obscured AGN and intriguing differences in how mergers affect the evolution of high gas fraction galaxies.
Credits: (left image) NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University). Right image: https://ui.adsabs.harvard.edu/abs/2013ApJ...771..120P/abstract