Tidal disruption events
A new reconstruction tells the full story of a star ripped apart by a ravenous black hole in a tidal disruption event
Scientists have used a sophisticated simulation to reconstruct the brutal death of a star that wandered too close to a supermassive black hole and was shredded to bits. The team, led by researchers from the Hebrew University of Jerusalem’s Racah Institute of Physics, retold the entire story of this so-called tidal disruption event (TDE) for the first time and saw an unknown type of shock wave occur during the gory process. They also found that the dissipation of these shock waves powered an exceptionally intense flare during the event’s brightest weeks.
In addition to explaining the brightest periods of these violent star-destroying events, the findings could help astronomers use TDEs to discover the properties of supermassive black holes, like their mass and rate of spin, and test the limitations of Einstein’s theory of general relativity. TDEs happen 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. As the star draws close to the supermassive black hole, the black hole’s massive gravitational influence generates immense tidal forces within the star. This is the result of the gravitational force at the closest hemisphere of the star to the black hole being much greater than that at the farther end. This tidal force causes the star to be stretched vertically while it is squeezed horizontally. This turns the star into a thin strand of stellar plasma in a process known as spaghettification.
This spaghettified plasma falls towards the black hole; as this happens, it’s heated by a series of shock waves. This causes the plasma to fire off a highly luminous flare that can outshine the combined light of every star in the surrounding galaxy for weeks or even months. The simulation, created by Racah scientists Elad Steinberg and Nicholas Stone, gets deeper into TDEs, recreating a complete picture of these events, from the star being captured by the black hole, through the initial disruption of the star until the peak of the flare. This event reconstruction was possible thanks to pioneering radiation-hydrodynamics simulation software developed by Steinberg.
The cosmic crime scene investigation revealed a previously unknown type of shock wave occurring during the TDE, showing that these events dissipate energy at a faster rate than scientists thought. This finding told the team that the brightest peri
