Hebrew University finds first evidence of delayed radio outbreaks after star is destroyed by black hole

A team of researchers at the Hebrew University of Jerusalem (HUJI) led by Dr. Assaf Horesh has discovered the first evidence of radio appearances broadcast just long after a star is destroyed by a black hole. Published in the newspaper Nature Astronomy, the discovery relied on ultra-powerful radio telescopes to study these catastrophic cosmic events in distant galaxies called Tidal Disruption Events (TDEs). Although researchers knew that these events trigger the release of radio flares, this latest discovery saw these flares emitted months or even years after stellar disruption. The team was led by Dr. Horesh, of the Racah Institute of Physics, in Hebrew, along with NASA’s director of the Swift space telescope, Professor Brad Cenko, and Dr. Iair Arcavi, Tel Aviv University.

“According to existing theories about how these events occur, if no radio broadcast has been discovered immediately after the outage, it is not expected to occur later,” says Dr. Horesh. “However, we decided to conduct one last radio observation six months after the star’s destruction, and surprisingly we discovered a bright radio broadcast. Once we discovered this delayed radio burst, we continued collecting data for a year, during which the radio emission disappeared In addition, we found a second delayed flare, four years after the initial discovery of stellar interruption.This is the first discovery of these delayed radio flares of these events, when a star is interrupted by a black hole. “

Flares are believed to be caused by a huge beam of velocity fired when the star is destroyed and sucked into the black hole or as a result of the explosion of debris from the explosion.

Analysis of the delayed radio bursts led the research team to several conclusions.

First, they now believe that new models should be developed to explain such a long delay in radio flare emission. Second, these delayed radio lights may be a common phenomenon, but to find more, teams will need to stay focused on the observations surrounding the affected areas long after the initial outage. Third, it is possible that a substantial amount of stellar debris will increase (introduce) into the black hole, but only long after the star has been destroyed.

“What led to the delay and what the exact physical process responsible for this late emission are are still open questions,” Dr. Horesh says. “In light of this discovery, we are actively looking for more delayed radio outbreaks at other tidal outage events.”

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