A black hole in the center of a distant galaxy behaves like no other black hole astronomer. Every 9 hours, the black hole about 250 million light-years away in the center of the galaxy GSN 069 sends a bright X-ray beam to Earth. It is an active black hole, so it always devours matter. In doing so, this matter warms up and emits some light as it falls in the direction of the event horizon around the singularity beyond which no light or matter can escape.

In 2018, researchers using the European Space Agency’s XMM-Newton telescope (ESA) determined that the black hole GSN 069 would be about 100 times brighter in the X-ray spectrum at each peak of this 9-hour cycle. It was totally unexpected, said Giovanni Miniutti, astronomer at the Spanish Center for Astrobiology and lead author of a new paper on the black hole, in a statement by ESA.Huge black holes flicker regularly like a candle, but the fast, repetitive changes in GSN 069 from December are something completely new.

The researchers did not give a definitive explanation for the phenomenon. But it is clear they wrote that there is a kind of gap or instability in the accretion disk, the ring of infallible material that surrounds the black hole. Maybe something on the disk itself causes the matter to fall into the black hole in a regular pattern, or maybe something in its environment (maybe another black hole) will disrupt the disk in a cyclic way, the researchers say. Although astronomers have never seen such a pattern around another black hole, Miniutti and his team suggested that certain strange phenomena discovered elsewhere in space could be related to this type of pattern. In the past, astronomers have noticed that black holes suddenly became brighter for reasons they could not explain.

It is possible that these brightenings were parts of similar patterns. The black hole GSN 069 is not as big as many of the black holes that form the nucleus of a galaxy, the researchers noted. And the 9-hour period is probably bound to some extent by the speed with which the black hole turns.

Larger black holes would take much more time to complete a full rotation.So if you have a similar pattern, it could take weeks or months. And x-ray observatories rarely monitor a single black hole for so long. The researchers are not sure which physical phenomenon causes regular flaring.

But one possibility is the formation of an electron cloud in the immediate vicinity of the black hole – a phenomenon that is already believed to exist due to irregularities in the X-ray emission of some other black holes. The paper was published today (September 12) in the journal Nature.

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