a supermassive black hole challenges astronomical theories

Since 2011, astronomers have been observing a supermassive black hole located in a distant galaxy. Everything was normal until In 2018 the corona surrounding the black hole suddenly disappeared to reappear months later, an unprecedented event to which an even stranger behavior has been added.

The European Space Agency’s X-ray space observatory, XMM-Newton, has detected that this black hole, called 1ES 1927+654 and located one hundred million light years away, it emits flashes of X-rays at an increasing rate: before they occurred every 18 minutes and now they occur every seven. This spectacular acceleration of X-rays has never been seen in a black hole.

For astronomers, the behavior of this black hole challenges the idea that matter always falls into these types of objects and points to a possible source of gravitational waves.

Although they consider several hypotheses to explain the flashes, they believe that it is most likely that they are a rotating white dwarf – an extremely compact core of a dead star – orbiting the black hole and approaching its event horizon, the limit beyond which nothing can escape the pull of gravity.

A white dwarf that refuses to be swallowed?

If this is the case, the white dwarf would be doing an impressive balancing act and approach the edge of the black hole without falling into it.

“This would be the closest object we know of around a black hole,” he says. Megan Mastersona physicist at the Massachusetts Institute of Technology (MIT), who led the study, and co-author of the research. “This tells us that objects like white dwarfs may be able to live very close to an event horizon for a relatively long period of time,” he adds.

Astronomers believe that XMM-Newton is showing us that black holes They devour matter in more complex ways than astronomers originally thought.

The team will present their findings at the 245th meeting of the American Astronomical Society in National Harbor, Maryland, and will publish the results in an upcoming paper in Nature.

Gravitational monsters

Black holes are gravitational monsters that capture matter or energy that crosses their ‘surface’ called the ‘event horizon’.

In its fall towards the black hole – a process known as accretion– the doomed matter forms a disk around the black hole and the gas in the accretion disk heats up and emits mainly ultraviolet (UV) light.

The UV rays They interact with a cloud of gas and dust that surrounds the black hole and the accretion disk (known as the corona) and these interactions generate the X-rays that XMM-Newton can capture.

In July 2022, XMM-Newton observed that something strange was happening,” Masterson explains.

Scientists believe that these oscillations could suggest that a massive object, such as a star, is embedded in the accretion disk and rapidly orbits the black hole on its way to being engulfed. As the object approaches the black hole, the time it takes to orbit decreases, causing the frequency of the oscillations to increase.

Calculations showed that this orbiting object is probably a stellar corpse or white dwarfwith about 0.1 times the mass of the Sun, traveling at incredible speed and completing an orbit of about 100 million km, approximately every eighteen minutes. For two years, the oscillations increased in intensity and frequency.

In March 2024, XMM-Newton again observed and the oscillations were still there. The object was now traveling at half the speed of light and completed one orbit every seven minutes. Whatever was in the accretion disk, it stubbornly refused to be devoured by the black hole.