Rutgers University Astrophysics Seminar

There are several outstanding problems facing our understanding of galaxy formation and evolution, including the apparent shortfall of observed dwarf galaxies compared to theoretical expectations. The galaxy mass function is often used to characterize the galaxy population for comparison with the halo mass function from simulations of dark matter. Although galaxy mass is typically defined by the stellar mass, for low-mass galaxies, the cold atomic gas can be the dominant observable mass component. Thus, I will present both stellar and cold-baryonic (stars + cold atomic gas) mass functions of galaxies and galaxy groups in the RESOLVE and ECO surveys, two volume-limited galaxy surveys that are complete for galaxies with cold baryonic mass > 109 M☉. I will focus on several key results from my thesis, including that the galaxy cold-baryonic mass function rises with a steeper low-mass slope than the stellar mass function and that the galaxy mass function is dependent on group halo mass, suggesting that group formation processes potentially cause the shortfall of observed galaxies.