Researchers have long known that when two galaxies approach each other and merge, the supermassive black holes at their centers form a pair and are eventually expected to merge as well.  It is precisely these mergers that are considered one of the sources of the gravitational-wave background — a faint “hum” of spacetime detected in recent years. However, the role played by the geometry of the collision in this process has remained an open question. 

Graduate student Sena Ghobadi of the Georgia Institute of Technology’s School of Physics, along with her colleagues, has developed three-dimensional dynamic models of such collisions. 

A similar story appeared in Sky & Telescope.