Institute for Advanced Study, Princeton | 2019 Oct 16
At the center of our galaxy, millions of stars whirl in orbits around a supermassive black hole. This circuit can take anywhere from a few hours for stars close to the event horizon of the black hole to thousands of years for their distant neighbors. The nature of the dance—how the stars interact collectively through their gravitational forces—can vary from galaxy to galaxy.
... scientists ... have taken the first steps toward understanding the collective orbital patterns that emerge in star clusters surrounding a supermassive black hole. By studying these star clusters and how they evolve, researchers are gleaning new insights into the behavior of supermassive black holes and their influence over their stellar surroundings.
Based on a series of numerical models and simulations, the team has shown that black hole star clusters can undergo a phase transition from a spherical state to a lopsided state when they are cooled below a critical dynamical temperature. This phase transition, in some senses, is similar to the phase transition that occurs when a liquid changes into a solid. Just as molecules may shift from a disordered liquid state to a state where they are frozen in place, these star clusters are capable of achieving equilibrium in either a disordered (spherical) or an ordered (lopsided) structure, depending on their properties and environment. ...
Order-Disorder Phase Transition in Black-Hole Star Clusters ~ Jihad Touma, Scott Tremaine, Mher Kazandjian
- Physical Review Letters 123(02):1103 (12 Jul 2019) DOI: 10.1103/PhysRevLett.123.021103
- arXiv.org > astro-ph > arXiv:1907.01555 > 02 Jul 2019