Some 100 million light-years away, a supermassive black hole’s circle of light vanished, but then reappeared after a few hours.
Researchers observed how the corona - the circle of light which is basically a collection of high-radiation particles that surround a black hole’s event horizon - of 1ES 1927+654, a supermassive black hole, disappeared for reasons unknown after its usual brightness rose about 40 times higher. The black hole then went completely dark to the point that it was undetectable in all sorts of wavelengths from different telescopes that were used to observe it.
These observations were made possible through the ASSA-SN, or All-Sky Automated Survey for SuperNovae. It is a collaborated program for wholesome observation of the main supernova, led by Ohio State University. 20 telescopes are placed all across the north and south hemisphere that conduct observations of the sky at least once a day. Other telescopes of various types were then applied just to observe the sudden change inactivity. The team even sought the help of NASA’s NICER, which resides in the International Space Station, to capture X-ray photons.
According to astronomers, this activity should typically occur within thousands to millions of years. Much to their surprise, this one happened within just a single year, and showed changes ‘by a factor of 100 in eight hours’.
Just when they thought that the corona has completely vanished, gradual spikes in brightness were recorded as the black hole started to pull matter once again and began building another corona, yet again emitting high radiation energy that contributes to the black hole’s luminosity.
The working hypothesis is that a star could have rebounded within the corona and disrupted the usual gravitational flow, resulting in all of the material in the circle being devoured by the black hole. With the absence of radiation-emitting material around the event horizon, there was a drastic decrease in its brightness about 10,000 times within a single year. It could have also possibly caused a disturbance in the magnetic field that holds the structure of the black hole, to the extent that made it unable to sustain its existing corona.
A new corona has been recreated, but the black hole’s brightness wasn’t the same as it originally was. Continuous observations are still being done on 1ES 1927+654, and scientists are on alert for any more unexpected activity from this black hole.
Astrophysicists from Chile have published their study on this phenomenon.