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Home / Science / New model explains what we see when a massive black hole devours a star

New model explains what we see when a massive black hole devours a star



A star that moves too close to the supermassive black hole in the center of its galaxy is torn apart by the gravity of the black hole in a massive catastrophe called Tide Disruption (TDE). A new study, led by theoretical astrophysicists at the Niels Bohr Institute of the University of Copenhagen and UC Santa Cruz, provides a unified model that explains recent observations of these extreme events.

This groundbreaking study, published in Astrophysical Journal Letters, provides a new theoretical perspective for a rapidly growing field of research

"Only in the last decade have we been able to differentiate TDEs from other galactic phenomena, and the new model will provide us with the basic framework for provide understanding of these rare events, "said co-author Enrico Ramirez-Ruiz, Professor and Chair of Astronomy and Astrophysics at UC Santa Cruz and Niels Bohr Professor at the University of Copenhagen

In most galaxies, the central black hole resting, no material consumes actively and therefore does not emit any light. Tidal hazard events are rare and occur only once every 1

0,000 years in a typical galaxy. However, when an unfortunate star is torn apart, the black hole is "overfed" with stellar debris for a while and emits intense radiation.

"It's interesting to see how materials get into the black hole under such extreme conditions," said first author Jane Lixin Dai, assistant professor at the University of Copenhagen, who led the study.

"As the black hole eats the star gas, it emits a large amount of radiation Radiation is what we can Observe and use, we can understand the physics and calculate the properties of the black hole extremely interesting to hunt for tidal events. "

While the same physics is expected in all tidal events, about two of which have been observed dozens, the observed properties of these events have varied widely. Some emit mainly X-rays, while others emit predominantly visible and ultraviolet light. Theorists have struggled to understand this diversity and to assemble different parts of the puzzle into a coherent model.

In the new model, the observer's viewing angle takes into account differences in the observations. Galaxies are randomly aligned with the line of sight of Earth observers, who see various aspects of a tidal disturbance event depending on their orientation.

"It's like a veil covering part of an animal," Ramirez-Ruiz explained. "From some angles we see an exposed beast, but from other angles we see a covered beast. The beast is the same, but our perceptions are different."

The model developed by Dai and her collaborators combines elements of general relativity, magnetic fields, radiation and gas hydrodynamics. It shows what astronomers can expect when they look at tidal events from different angles, so that researchers can fit different events into a coherent framework.

Exploration projects planned for the next few years are expected to provide much more data on tidal disturbances and will help to significantly expand this Dai research area. These include the Transient Survey Survey (YSE), led by the DARK Cosmology Center at Niels Bohr Institute and UC Santa Cruz, and the Chile-built Large Synoptic Survey Telescopes.

"We will be hundreds to thousands of tidal events in a few years, which will give us many" labs "to test our model and use it to understand more about black holes," Dai said.

In addition to Dai and Ramirez-Ruiz, the co-authors include Jonathan McKinney, Nathaniel Roth and Cole Miller at the University of Maryland, College Park. To solve the puzzle, state-of-the-art computer-aided tools were used and the simulations were performed by Dai and Roth on the recently acquired large computer cluster, which was made possible by a grant from the Villum Foundation for Jens Hjorth, director of DARK Cosmology Center, as well as from the US National Science Foundation and NASA funded clusters.

Research work

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University of California – Santa Cruz

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