Supermassive black hole on a killing spree is using dead star remains as weapon

California

NASA has discovered a supermassive black hole that killed one star and is now using the wreckage to destroy another star or black hole. The Chandra X-ray Observatory and other telescopes combined to spot the black hole that is on a killer mission.

The findings were published in the journal Nature on Oct 9. 

In 2019, a burst of light was observed by an optical telescope in California. A black hole had shredded a star that got too close to it using its powerful tidal forces. The event was later categorised as a "tidal disruption event", or TDE. All that remains after the event is a disk that orbits the black hole.

This disk grew in size over time, expanding at a regular rate. This has brought it in the path of another star, possibly a stellar-mass black hole. This black hole is orbiting the massive black hole. While earlier it was at a safe distance, now it is repeatedly crashing into the disk left behind by the dead star.

This happens every 48 hours, with each collision resulting in a burst of X-rays that Chandra captured.

“Imagine a diver repeatedly going into a pool and creating a splash every time she enters the water,” said Matt Nicholl of Queen’s University Belfast, United Kingdom, the study’s lead author.

In this case, "The star is like the diver and the disk is the pool." 

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"Each time the star strikes the surface, it creates a huge ‘splash’ of gas and X-rays. As the star orbits around the black hole, it does this over and over again.”

X-ray bursts

The X-ray burst is a cosmic phenomenon that occasionally occurs in the universe and has been named "quasi-periodic eruptions", or QPEs. Astronomers had been observing them for some time but were not able to pinpoint the reason.

The discovery of this supermassive black hole on a killing spree is proof that TDEs and QPEs are connected, experts think. 

Researchers believe that QPEs happen when an object smashes into the disk left behind after the TDE. The study authors say that this might not be the case with all of them, but they are the source of at least some QPEs.

“There had been feverish speculation that these phenomena were connected, and now we’ve discovered the proof that they are,” said co-author Dheeraj Pasham of the Massachusetts Institute of Technology.

“It’s like getting a cosmic two-for-one in solving mysteries.”

The Chandra data was obtained during three observations, each with a gap of about 4 to 5 hours. Chandra time exposure was about 14 hours and it revealed only a weak signal in the first and last chunks but a very strong signal in the middle observation.