At the center of most large galaxies lives a supermassive black hole (SMBH). The Milky Way has Sagittarius A*, a mostly dormant SMBH whose mass is around 4.3 million times that of the sun. But if you look deeper into the universe, there are vastly larger SMBHs with masses that can reach up to tens of billions of times the mass of our sun.
Black holes grow in mass by gravitationally consuming objects in their near vicinity, including stars. It’s a catastrophic and destructive end for stars unlucky enough to be swallowed by SMBHs, but fortunate for scientists who now have an opportunity to probe otherwise-dormant centers of galaxies.
TDEs Light the Way
As the name implies, black holes do not emit any light of their own, making them very difficult for researchers to observe. But when a star comes sufficiently close to a supermassive black hole, it can be destroyed by the black hole’s immense tidal gravitational field through an interaction that is, effectively, an extreme instance of the Earth’s tidal interaction with the Moon. Some of the tidally destroyed material falls into the black hole, creating a very hot, very bright disk of material as it does so. This process, known as a tidal disruption event (TDE), provides a light source that can be viewed with powerful telescopes and analyzed by scientists.
TDEs are relatively rare — predicted to take place roughly once every 10,000 to 100,000 years in a given galaxy. One to two dozen TDEs are typically detected annually, but with the advent of new technology like the Vera C. Rubin Observatory, currently under construction in Chile, hundreds are anticipated to be observed in the coming years. These powerful observatories scan the night sky for rising and falling sources of light, and thus “survey” the cosmos for time-changing astronomical phenomena. Using these surveys, astrophysicists can perform studies of TDEs to estimate the properties of SMBHs and the stars that they destroy. One of the things that researchers…