Scientists have used sophisticated simulations to reconstruct the brutal death of a star that wandered too close to a supermassive black hole and was torn into bits.
The team, led by researchers from the Rakah Institute of Physics at the Hebrew University of Jerusalem, retold the full story of the so-called tidal disturbance event (TDE) for the first time, and witnessed a previously unknown type of shock wave occurring during the bloody process. They also found that the dissipation of these shock waves led to an exceptionally intense glow during the brightest weeks of the event.
In addition to explaining the brightest periods of these violent star-destroying events, the results could help astronomers use TDEs to discover the properties of supermassive black holes, such as their mass and spin rate, and test the limits of Einstein’s theory of general relativity. .
The results were published on January 17 in the journal Nature.
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Stars destroyed by a black hole undergo a shock
TDEs occur when a star’s orbit approaches a supermassive black hole with a mass millions or billions of times greater than the mass of the Sun. When a star approaches a supermassive black hole, the black hole’s enormous gravitational influence generates enormous tidal forces inside the star.
This is a result of the fact that the gravitational force in the half of the black hole closest to the star is much greater than that in the farther end. This tidal force causes the star to expand vertically while being compressed horizontally. This turns the star into a thin ribbon of stellar plasma in a process known as “spaghetti.”
This pasty plasma bounces toward the black hole, and as it does so, it is heated by a series of shock waves. This causes the plasma to emit an intensely luminous glow that can outshine the combined light of every star in the surrounding galaxy for weeks or even months.
The simulation created by RACA Institute of Physics scientists Elad Steinberg and Nicholas Stone delves deeper into TDEs, recreating for the first time the full picture of these events, from the black hole’s takeover of the star, through the star’s initial perturbation, to the TDE’s luminous peak.
The reconstruction of the event was made possible thanks to pioneering radiohydrodynamic simulation software developed by Steinberg.
Investigation of the cosmic crime scene has revealed a previously unknown type of shock wave that occurs during a TDE, showing that these events dissipate energy at a faster rate than scientists thought. This result told the team that the brighter periods of the TDE are powered by shock waves and associated energy dissipation.
According to the researchers, astronomers can continue to explore the mechanisms of these powerful shock waves using real-world observations of violent encounters between supermassive black holes and stricken stars.