Tim Waters (Physics & Astronomy) and his latest work are the subject of a NASA press release, "Black Holes May Generate ‘Tsunamis’ in Escaping Gas." Based on a paper published in The Astrophysical Journal and co-authored with Daniel Proga and Randall Dannen (both Physics and Astronomy) this article describes how oceanic disturbances akin to tsunamis as well as common weather patterns such as Kármán vortex streets should occur in the center of active galaxies, also known as 'active galactic nuclei' or AGN. The plasma environment of AGN is governed by the equations of gas dynamics, so it is commonplace to see phenomena well known from fluid dynamics. The accretion disks around supermassive black holes are believed to be turbulent, for example. It was nevertheless a surprise to see the clear signature of a Kármán vortex street in their simulations of the disk atmosphere. On earth, these vortex shedding patterns commonly appear within clouds after winds impact a hard surface like a mountain. In the researchers' simulations, these patterns are instead formed by a wind impacting an 'AGN cloud,' which is just gas that is significantly more dense than the plasma in the wind. In response to the impact, this cloud in turns travels outward and takes on a tsunami-like appearance. The researchers' simulations can be viewed online. Waters is a postdoctoral scholar, while Dannen is a graduate student.
