Jan 17, 2025 09:00:00

Mystery of strangely glowing black holes may be linked to 'white dwarfs'

The supermassive black hole '

1ES 1927+654 ,' located 270 million light years from Earth, has been observed to behave in a way that contradicts conventional theories about the black hole environment, and its unpredictable state has attracted the attention of researchers and astronomy enthusiasts. In a study presented at the 245th Meeting of the American Astronomical Society by physicists from the Massachusetts Institute of Technology (MIT), they concluded that the unusual observations for a black hole are caused by the remnants of a star called a ' white dwarf .'

[2501.01581] Millihertz Oscillations Near the Innermost Orbit of a Supermassive Black Hole
https://arxiv.org/abs/2501.01581

A strange black hole is acting even stranger | Mashable
https://mashable.com/article/black-hole-white-dwarf-star-mystery

The object, named '1ES 1927+654 (hereinafter referred to as 1ES),' is said to have the mass of one million suns. It has been observed to be moving in unprecedented ways in previous observations of black holes, such as the sudden disappearance and subsequent return of the coronal layer surrounding the black hole, and the frequency of X-ray light emission, which was once every 18 minutes, decreasing to seven minutes over time. A 2020 study showed that the extreme movements of 1ES are related to instability in the magnetic field around the black hole, casting doubt on the conventional model of black hole accretion.

At the 245th Meeting of the American Astronomical Society, held from January 12 to 16, 2025, MIT physicist Megan Masterson and others presented a new perspective on 1ES.

According to the research, the strange behavior of 1ES is caused by a 'white dwarf' that came very close to the black hole. A white dwarf is the remains of a dead star and is made up of matter with degenerate electrons. In terms of the Sun, it has a mass similar to that of the Sun, but its volume is only about the same as that of the Earth, and is characterized by its extremely high density.

What are the only celestial bodies that will remain when the universe comes to an end, the 'white dwarf' and the 'black dwarf'? - GIGAZINE

The paper reports the discovery of a very significant millihertz-frequency gravitational wave event around the supermassive black hole 1ES. This phenomenon, called quasi-periodic oscillations (QPOs), is a phenomenon in which X-rays emitted from celestial objects flicker around a specific frequency, and is observed in white dwarfs and black holes.

Masterson and his team conducted a simulation to see what was causing the unusual energy bursts around 1ES. At this time, the conventional model could not explain all of the QPOs observed in 1ES, so tests including X-ray monitoring became important. As a result, it was shown that the white dwarf's close proximity to the black hole may have peeled off the dense exterior around the black hole, generating the X-ray pulse. The faster emission frequency can also be explained by the white dwarf's closer proximity to the black hole.

'Normally, when an object approaches a black hole, it gets shattered into pieces and then moves away from the black hole,' said Erin Cara, an associate professor of physics at MIT. 'But because white dwarfs are so dense and compact, they're very hard to break apart, so they may persist very close to the black hole. If this scenario is correct, we may be at a tipping point where we can see the white dwarf move away from the black hole.'