From boredom to rupture: A huge black hole awakening

Although we know that supermassive black holes (millions of times the mass of our sun) lurk in the centers of most galaxies, their nature makes them difficult to discover and learn. Contrary to the popular idea that black holes constantly “devour” matter, these gravitational monsters can take a long time during the dormant, inactive phase.

The black hole in the center of SDSS11335+0728 is correct, which is a distant and inconspicuous galaxy in Virgo constellation 300 million light-years. After decades of inactive, it suddenly glowed and recently began to produce unprecedented X-ray lights.

The first sign of the event came at the end of 2019, when the Milky Way unexpectedly began to shine brightly, attracting the attention of astronomers. After several years of research, they concluded that the anomalous changes they saw could be the result of a sudden “opening” of the black hole – entering an active phase. The bright, compact, central region of the galaxy is now classified as an active galaxy core nicknamed “Ansky”.

“When we first saw Ansky light up in optical images, we triggered follow-up observations using NASA’s Swift X-ray space telescope, and we checked archived data from the eROSITA X-ray telescope, but at the time we didn’t see any evidence of X-ray emissions,” says Paula Sánchez Sáez, a researcher at the European Southern Observatory, Germany, and leader of the team that first Activation of explored the black hole.

Ansky wakes up

Then, in February 2024, a team led by researcher Lorena Hernández-García from the University of Valparaiso in Chile began to see Ansky’s X-ray bursts over almost regular time periods.

“This rare event provides astronomers with an opportunity to use X-ray space telescopes XMM-Newton and NASA, better, Chandra and Swift to observe the behavior of black holes in real time. This phenomenon is known as a quasi-magazine burst, or QPE. Lorena.

“The first QPE series was discovered in 2019, and since then we’ve only discovered a few. We don’t understand what’s causing them yet. Learning about Ansky will help us better understand black holes and their evolution.”

“XMM-Newton played a key role in our study. It is the only X-ray telescope that is sensitive enough to detect X-ray background light between bursts. Using XMM-Newton, we can measure the acquisition of Dim Ansky, which allows us to calculate how much energy Ansky emits when it lights up and starts to flicker.”

Uncover confusing behavior

The gravity of a black hole captures matter too close to it and can tear it apart. For example, matter from captured stars will be scattered into a hot, bright, fast-rotating disc called accumulating disc. The current idea is that QPE is interacted by an object (probably a star or a small black hole) with this accumulation disk, which is related to the destruction of the stars. But there is no evidence that Ansky has destroyed a star.

The extraordinary characteristics of Ansky’s repeated outbreaks prompted the research team to consider other possibilities. The accumulation disc can be gas captured by a black hole from its vicinity, rather than a disintegrating star. In this case, the X-ray flare will come from a high-energy impact in the disc, repeatedly propagating by a small celestial object and destroying the orbital material.

“Ansky’s X-ray bursts ten times more than the X-rays we see from typical QPEs than we see,” said Joheen Chakraborty, a team member and doctoral student at the Massachusetts Institute of Technology in the United States.

“Each of these bursts releases a hundred times more than we’ve seen elsewhere. Ansky’s burst also showed the longest pace ever, about 4.5 days. This pushes our models toward their limits and challenges our existing ideas about these X-ray flashes.”

Watching the movement of a black hole

Being able to watch Ansky’s development in real time is an unprecedented opportunity for astronomers to learn more about black holes and the vibrant events of their power.

“For QPE, we are still having more models than data, and we need more observations to understand what is going on,” said Erwan Quintin, an ESA researcher and X-ray astronomer.

“We think QPE is the result of small objects captured by larger objects. Ansky’s burst seems to be telling us a different story. These repetitive bursts may also be related to gravity fluctuations, and ESA’s future mission Mission Lisa may be able to capture.”

“It is crucial to have these X-ray observations that will complement gravitational wave data and help us solve the confusing behavior of large black holes.”