Shedding Light on Hidden Massive Black Holes using Cosmological Simulations

Massive black holes (MBHs) ranging from 10 thousand to 10 billion solar masses exist at the centers of nearly every massive galaxy, as well as many low mass dwarf galaxies. The origin and evolution of these black holes and their role in galaxy evolution remain important outstanding questions in astrophysics. Cosmological simulations have long been useful tools for understanding many aspects of galaxy formation, but modeling MBHs is an ongoing challenge. I will discuss how recent improvements to modeling MBHs implemented in the Romulus Simulations have allowed for new insight into two very interesting populations: MBHs within low mass galaxies and "wandering" MBHs that exist far from the centers of galaxies. These notoriously elusive MBHs are likely the keys to understanding their origin and simulations like Romulus are necessary to interpret current and future electromagnetic and gravitational wave detections. I will present results from Romulus on the dynamical evolution of MBHs in galaxy mergers and the resulting population of off-center, "wandering" MBHs. I will also show new predictions for the abundance and properties of MBHs in dwarf galaxies and how they may influence the evolution of their low mass hosts. Finally, I will touch on current work simulating MBHs in merging dwarf galaxies at very high resolution with the goal of understanding the sources for gravitational waves detectable with LISA.