Mysterious flashing seen near supermassive black hole. Astronomers have an idea what it is

A cosmic mystery surrounding a black hole some 270 million light-years from the Milky Way is deepening.

For years, astronomers have been perplexed by this particular supermassive black hole, a behemoth as large as a million suns in a distant galaxy. In 2018, astronomers observed that the black hole’s corona – a cloud of whirling, white-hot plasma – suddenly disappeared before reassembling months later.

Now, the black hole has once again demonstrated strange features that teams of astronomers around the world have professed to never before seeing: Plasma jets moving at nearly one-third the speed of light, and rapid X-ray flashes from the black hole's edge steadily increasing in frequency.

But researchers believe they have identified a likely culprit for the unusual behavior.

It's believed that a dead stellar remnant, or white dwarf, could be spinning precariously on the edge of the black hole, causing the explosions of high-energy light.

“This would be the closest thing we know of around any black hole,” Megan Masterson, a graduate physics student in at the Massachusetts Institute of Technology who was part of a team that made the discovery, said in a statement. “This tells us that objects like white dwarfs may be able to live very close to an event horizon for a relatively extended period of time.”

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Black hole first observed acting strangely in 2018

The black hole, the official name of which is a mouthful (1ES 1927+654), is located in the distant constellation Draco.

Astronomers have been monitoring the black hole for years, primarily since 2018 when the mass was observed changing its properties with a major X-ray outburst, Eileen Meyer, an associate professor the University of Maryland Baltimore County said in a NASA news release. After the outburst, the black hole appeared to return to a quiet state, with a lull in activity for nearly a year.

Teams of astronomers at Meyer's university and many other institutions have been keeping an eye on the black hole ever since.

The vigilance paid off when, in April 2023, a team at the university and NASA’s Goddard Space Flight Center in Greenbelt, Maryland, noted a steady, months-long increase in low-energy X-rays. The researchers made new radio observations, discovering that a strong and unusual radio flare was underway, according to NASA.

Astronomers at MIT also observed the behavior in 2018 as the black hole’s corona went dark, then slowly rebuilt itself over time. For a while, the newly reformed corona was the brightest X-ray-emitting object in the sky, according to a news release from MIT.

In 2022, the team at MIT combed through observations of the black hole taken by the European Space Agency’s XMM-Newton, a space-based observatory that detects and measures X-ray emissions from black holes and other cosmic sources. They also noticed that X-rays from the black hole appeared to pulse with increasing frequency.

Astronomers detect rapid X-ray flashes around black hole

Between 2022 and 2024, MIT astronomers led by Masterson detected rapid X-ray flashes originating from the black hole in which the brightness repeatedly rose and fell by 10% every few minutes.

Within those two years, the fluctuation period ramped up from every 18 minutes to just seven minutes – the first-ever measurement of its kind around a supermassive black hole.

If this signaled an orbiting object, astronomers determined the body was moving at half the speed of light. Then something unexpected happened: the fluctuation period stabilized.

Further baffling astronomers, radio data from February, April and May 2024 reveals what appear to be jets of ionized gas, or plasma, extending from either side of the black hole – a rarity for such a monster black hole, astronomers say.

Could the flashing be from a white dwarf?

Astronomers believe the source of the flashing is somewhere very close to the black hole, perhaps even within a few million miles of the event horizon – a theoretical boundary known as the "point of no return" where light and other radiation can no longer escape.

A small black hole would plunge straight into the event horizon, while a normal star would quickly be torn apart by tidal forces. But astronomers theorize that a low-mass white dwarf, a compact core of a dead star about as large as Earth, could remain intact, even as it sheds some of its matter while approaching the event horizon.

When any object gets close to a supermassive black hole, they're typically ensnared in a powerful gravitational pull and unable to escape. If the circling object is indeed a white dwarf, the body would be pulling of a precarious balancing act, teetering on the black hole’s edge without falling in.

To cause the fluctuations that astronomers observed, the orbiting mass would be expected to generate ripples in space-time, called gravitational waves, as it approached the event horizon.

For this reason, astronomers believe the gravitational waves would be observable during an upcoming mission to study the phenomenon. The LISA mission, led by the European Space Agency, aims to within the next decade send a fleet of three space probes into orbit to study gravitational waves, or distortions in space-time caused by violent events such as the collision of black holes.

The research was presented Monday at the 245th meeting of the American Astronomical Society in National Harbor, Maryland.

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]

This article originally appeared on USA TODAY: Astronomers may have an answer to strange flashes from black hole