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To 100 million light years from Earth , astronomers from several observatories were of stone to see how the brilliant corona of a supermassive black hole , the ring of ultra-bright high-energy particles more than a thousand millions of degrees of temperature that surrounds the black hole, disappeared suddenly and mysteriously.

Although the cause of this abrupt disappearance is unknown, researchers believe that something very strange had happened. Something like a star (trapped by the gravity of the black hole, “ bouncing ” through the spiral of materials in orbit and making everything around her, including the high-energy particles of the crown, fell suddenly to the inside of the hole, disappearing forever.

The result of this process was the surprising and precipitous decline of the brightness of the black hole, which dropped by a factor of 10,000 in less than a year. The discovery was just published in Astrophysical Journal Letters.

“What you expect is that any changes in luminosity so big that happen in time scales of many thousands or millions of years -ensures Erin Kara , of the Massachusetts Institute of Technology (MIT) and co-author of the research. But in this object, the brightness dropped to 10,000 times in a single year, and even came to fall by a factor of 100 in just eight hours, which is totally unknown and truly amazing”.

After the sudden disappearance of the corona, the researchers continued observing the black hole, and they saw how I began again to gather slowly the material around their outer edges to re-form their accretion disk rotating, which in turn started to emit high energy X-rays near the event horizon of the black hole. In this way, and in just a few months, the black hole generated a new crown, almost as bright as the original.

“this Is the first time that we see disappear a crown and return to rebuild,” continues Kara – and we are seeing that in real time. This will be really important to understand how the corona of a black hole feeds and the form of the nothing.”

it All started with a flash

In march of 2018, the investigators observed a strong and unexpected flash of 1 1927 + 654 , an active galactic nucleus, or AGN , which is a type of supermassive black hole with a brightness higher than the normal in the center of a galaxy. The brightness of the object increased suddenly up to 40 times its luminosity normal .

“it Was an AGN that we already knew,” explains Kara-, but was not too special. Suddenly, we realized that this AGN power would be very bright, what caught our attention, and we started to point towards him many other telescopes at many other wavelengths to look at it”.

The team, in effect, used multiple telescopes to observe the black hole in the bands of X-ray and optical wave ultraviolet. Most of those telescopes pointed regularly to the black hole, for example by recording observations during a whole day every six months. The team from MIT, however, observed daily the black hole with the small X-ray telescope NICER, NASA, installed aboard the International Space Station and equipped with sensors and detectors that are designed and built by researchers of the own MIT.

“NICER is great-ensures Kara – because it is very agile”. With him, the team could “take a look” for a while each day to the black hole and leave after free the telescopìo for other observations. Looking at it so often, Kara and his team quickly realized that the black hole quickly lost his crown, until it disappeared completely. “Just after passing by this enormous burst -reminds the researcher – we saw how the crown disappeared. Became undetectable, something that we had never seen before.”

The crown mysterious

physicists are not entirely sure what is causing exactly that it forms a corona around a black hole, but believe that it has something to do with the configuration of the field lines magnñetico that go across the accretion disk . In the outer regions of the swirling disk of material, these field lines have a configuration more or less simple. More closely, however, and especially along the event horizon, the line that once crossed, does not allow any object to come back out, the higher energy of the material of the disk may cause the magnetic field lines twist and break, to return later to connect. And that tangle of magnetic energy could spin particles at full speed around the hole, forming a crown that shines extraordinarily in the range of the x-rays.

Kara and his colleagues believe that if the crown really disappeared because of a star misguided, that star was first torn apart by the gravitational pull of the hole, and its remains scattered throughout the accretion disk. That could be the source of the bright flash captured in 2018. Called by astronomers the “interruption of the tide”, this event would have resulted in a large part of the disk material to fall suddenly into the black hole. And also would have been able to do that the magnetic field lines ” you re mad “, to the point of not being able to already generate and support a crown of high energy.

astronomers calculated that to cause the demise of the crown, the star must be within a radius of approximately 4 minutes light the center of the black hole. That is to say, about 75 million km, just to the side of the “beast”.

After you disappear, the crown has been formed again. It is not as bright as before, but the researchers are still looking if there are more surprises. “We want to watch him, says Kara-. He is still in that state unusual high flow, and maybe try to do something crazy, so I don’t want to miss that.”