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Israeli researchers have picked up radio broadcasts from a distant galaxy that they believe could drastically change understanding of black hole behavior.
When stars get close to black holes, they risk being torn apart. If so, much of the material is expected to be consumed by the black hole, in a process that has been speculated to take place in days and last for weeks.
But physicists at the Hebrew University of Jerusalem and Tel Aviv University raise the possibility of a still unexplained process that causes some black holes to disappear months or years before swallowing up the last remains of a destroyed star. .
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“There appears to be a physical process that we don’t yet understand that causes a long delay between the destruction of the star and the accretion of the black hole material,” Hebrew University physicist Assaf Horesh told the Times of Israel.
Illustration of a star torn apart by a black hole. The stellar debris is then accreted on the black hole. (Elen11 via iStock via Getty Images)
The peer-reviewed journal Nature Astronomy has just published the research of Horesh, Iair Arcavi of Tel Aviv University and the director of NASA’s Swift Space Telescope, Brad Cenko. After observing the optical radiation from the destruction of a star in a galaxy 700 million light years away in 2015, they began to search for radio broadcasts, hoping to detect them for a short time.
Following the destruction of a star, physicists believe that it is common for certain materials to enter the black hole that caused its death. As part of this process, other materials are chased by jets caused by magnetic fields around the black hole. Since it is returned at high speed, it is believed to create shockwaves which generate radio broadcasts.
3D rendering of a black hole (Philipp Tur via iStock by Getty Images)
Scientists have the experience of detecting it immediately after the destruction of a star became observable on Earth, but Horesh and his colleagues ended up breaking new ground, detecting emissions over a period of four years.
“We saw optical radiation after the star was destroyed and then no radio broadcast for months,” said Horesh, lead author of the new research. “We decided to give him what we thought was a last blow. Suddenly, six months later, there was a radio show, which faded for a year.
Diagram showing the timescale of detection of radio broadcasts by Israeli researchers after a star is destroyed. (Courtesy of Dr Assaf Horesh, Dr Iair Arcavi, et al)
“Then, four years after the initial sighting, we found that once again there was a very strong signal.”
According to him, the research suggests that the period during which a black hole consumes material from a star and rejects other material – generating radio emissions in the process – is longer “and a little more chaotic” than one might expect. thought so before. He added that his team was looking to expand their research by identifying more radio transmissions from various galaxies.
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