Hungry black hole 'switches on' as astronomers watch in surprise

One of the most dramatic instances of a black hole catching us off guard so far is J221951.

One of the most stunning "switching on" occurrences ever witnessed occurred when a supermassive black hole began gorging on nearby matter.

One of the brightest transients ever observed is J221951, which is fuelled by this voracious black hole. Transients are celestial phenomena or objects that undergo brief changes in brightness. The black hole is located exactly where a supermassive black hole would be anticipated to be—in the middle of a previously discovered galaxy. Astronomers are still unsure of the precise cause of the transitory event seen in J221951, though.

According to team member and University of Belfast astronomer Matt Nicholl, "discoveries of stars being torn apart and accreting black holes with enormously variable luminosities have greatly expanded our understanding of the different things that supermassive black holes can do." One of the most dramatic instances of a black hole catching us off guard so far is J221951.

It is currently unknown what the supermassive black hole, which is located about 10 billion light-years away, is consuming, but it's possible that J221951 is a star that got too close to the black hole and was violently ripped apart by tidal forces brought on by its incredibly strong gravity, a process known as spaghettification.

In this occurrence, known as a tidal disruption event (TDE), some of the stellar material from the shattered star would fall to the black hole's surface while other matter would be directed to the black hole's poles before being ejected at close to light-speeds, generating intense electromagnetic radiation.

The black hole in question might be producing this spectacular transient event through a variety of mechanisms, including the spaghettification of an unhappy star. J221951 may also be the consequence of a galaxy's central core transforming from a dormant to an active condition.

Galaxies' active galactic nuclei (AGNs) are brilliant regions at their centers that emit enough light to obliterate the combined light of all the other stars in the galaxy. Additionally, supermassive black holes provide their energy.

It may be possible to determine if J221951 is a fast-spinning black hole tidally disrupting a star or a new type of AGN switching on with further observation of the object.

observing the spectacular "switching on" at a galaxy's center

When two neutron stars or a neutron star and a black hole combine, powerful bursts of electromagnetic radiation called kilonovas are produced as a sort of transient event. Kilonovas start off being blue and gradually turn red over the course of several days. Although the transitory J221951 likewise had a blue appearance, it didn't quickly turn red or fade away as a kilonova would. Follow-up observations with space-based instruments like the Hubble Space Telescope and ground-based observatories like the Very Large Telescope (VLT) in Northern Chile's Atacama Desert helped to identify the characteristics of this transient.

"The important finding came when Hubble's ultraviolet (UV) spectrum ruled out a galactic origin. This demonstrates how crucial it is to keep a space-based UV spectrograph capacity for the future, according to team member and Mullard Space Science Laboratory researcher Paul Kuin.

The scientists concluded that J221951 must be one of the brightest occurrences ever witnessed with a source 10 billion light-years away. They will now strive to comprehend its cause better.

The ability to discern between the active galactic nuclei and tidal disruption event scenarios will be possible in the future, according to Oates. For example, if J221951 is connected to an AGN going on, we may anticipate that it will stop fading and start to brighten up again, however if J221951 is a tidal disruption event, we would anticipate that it will keep fading.

"Over the coming months and years, we will need to continue monitoring J221951 to record its late-night behavior."