What can happen to a star that wanders too close to the supermassive black hole in the centre of its galaxy. Astrophysicists have been struggling to understand this diversity and assemble different pieces of the puzzle into a coherent model.
But now thanks to a breakthrough study, published in Astrophysical Journal Letters, the study points out that the superstar will be torn apart by the black hole’s gravity in a violent cataclysm called a tidal disruption event (TDE), producing a bright flare of radiation. The research provides a new theoretical perspective via a computer model developed by astrophysicists and looks at the consequence of a “superstar sucked into the supermassive”.
The study led by theoretical astrophysicists at the University of Copenhagen’s (UOC) Niels Bohr Institute and UC Santa Cruz provides a unified model that explains recent observations of these extreme events. “Only in the last decade or so have we been able to distinguish TDEs from other galactic phenomena, and the new model will provide us with the basic framework for understanding these rare events,” said co-author Professor Enrico Ramirez-Ruiz, chair of Astronomy at UCSC and Niels Bohr Professor at the UOC.
How Big Are Black Holes?
Black holes can be big or small. The largest black holes are called “supermassive.” These black holes have masses that are more than 1 million suns together. In most galaxies, the central black hole is quiescent, not actively consuming any material and therefore not emitting any light.
Tidal disruption events are rare, only happening about once every 10,000 years in a typical galaxy. When an unlucky star gets torn apart, however, the black hole is “overfed” with stellar debris for a while and emits intense radiation. “As the black hole is eating the stellar gas, a vast amount of radiation is emitted. The radiation is what we can observe, and using it we can understand the physics and calculate the black hole properties,” said lead author Jane Lixin Dai, assistant professor at UOC.
While the same physics is expected to happen in all tidal disruption events, about two dozen of which have been observed so far, the observed properties of these events have shown great variation. Some emit mostly x-rays, while others emit mostly visible and ultraviolet light. “We will observe hundreds to thousands of tidal disruption events in a few years. This will give us a lot of ‘laboratories’ to test our model and use it to understand more about black holes,” Dai said.