UNC-CH Physics and Astronomy PhD Defense

Chris Frazer

“Gas Dynamics and Star Formation near Supermassive Black Holes”

The existence of young stars in the central parsec of the Milky Way’s Galactic Center (GC) is challenging to explain due to the extreme tidal field of the supermassive black hole (SMBH), Sgr A*, which is expected to disrupt any potentially star forming gas in its vicinity. Yet, numerical models indicate that star formation may occur in this region through two processes. First, the formation and fragmentation of a dense gas disk, which results from rapid gas inflow towards the SMBH, is the most likely origin for the observed stellar disk in the GC. Second, the extreme gravitational compression of low mass gas “clumps” on eccentric orbits around the SMBH provides an alternative explanation for isolated star clusters, as well as newly forming stars, that are not associated with the stellar disk. I build upon these previous theories of nuclear star formation by using three-dimensional grid-based radiative-hydrodynamic simulations to consider the role of ionizing radiation. I begin with an implementation of an adaptive radiative transfer routine for the Athena code. I then explore how radiation arising from accretion onto the SMBH may affect the process of gas inflow and stellar disk formation. I then consider the effect of radiation from existing stars on continued star formation occurring via the infall of low-mass gas clumps.