Speaker: Sanaea Rose (UCLA)
Collisions in Galactic Nuclei: Stars, Binaries, and Black Holes
Like most galaxies, the Milky Way harbors a supermassive black hole (SMBH) at its center. Surrounding the SMBH is a dense cluster of stars and stellar remnants. In this cluster, objects frequently collide and interact with one another. I will discuss the implications of direct collisions for the population of stars and stellar remnants surrounding the SMBH. While stars often reside in binary configurations, the dense environment at the Galactic Center (GC) works to destroy these systems. An observed stellar binary can therefore place constraints on the density of objects in its neighborhood, including the number of compact objects there. Generally challenging to detect, these compact objects are also affected by collisions with surrounding stars. Most stellar evolution models predict that black holes (BHs) cannot form above a certain mass. However, over many collisions, a stellar-mass BH can grow appreciably in size. Our results suggest that BHs above the maximum mass predicted by stellar evolution models may be ubiquitous in galactic centers. Many of these BHs can merge with the SMBH and emit gravitational waves. Additionally, collisions between stars and BHs have electromagnetic signatures. Lastly, I will comment on the role of stellar collisions in shaping the broader stellar population, for example, by creating more massive, rejuvenated stars.
