From boredom to burst: giant black holes awaken

We know that ultra-alpine black holes (millions of our sun) lurk in the heart of most galaxies, but their nature makes them difficult to find and study. In contrast to the common ideas of black holes, these gravity monsters are constantly “goble-up”, but can spend a long time in the inactive stages of dormant state.

This was true for the black hole at the center of SDSS1335+0728. This is a Virgo constellations that are not visible in the distance, 300 million light years away. After decades of inactivity, it suddenly lit up and recently began producing an unprecedented flash of X-ray light.

The first signs of activity appeared in late 2019 when the galaxy began to unexpectedly brighten up, attracting the attention of astronomers. After several years of research, they concluded that the unusual changes they saw were probably the result of the black hole suddenly being “on.” The bright, compact central region of the galaxy is classified as an active galactic nucleus known as “Ansky.”

“When I first saw Ansky’s light in optical images, I used NASA’s Swift X-ray telescope to trigger follow-up observations and checked the archive data from the Erosita X-Ray telescope, but found no evidence of X-ray emissions.” Hall activation.

Ansky wakes up

Then, in February 2024, a team led by Lorena Hernandez Garcia, a researcher at the University of Valparaiso in Chile, began to see bursts of x-rays from Anski almost regularly.

This work is featured in Nature Astronomy.

“This unusual event offers an opportunity for astronomers to observe black holes in real time using Xmmm-Newton and NASA’s better, Chandra and Swift. This phenomenon is known as a quasi-periodic eruption, Lorena.

“The first QPE episodes were discovered in 2019. Since then, only a handful have been detected. We don’t yet understand what causes them. Studying Ansky will help us to better understand black holes and how they evolve.”

“Xmm-Newton played a pivotal role in our research. It is sensitive to X-ray telescopes enough to detect X-ray background illumination between bursts. With XMM-Newton, you can measure how dimly lit Ansky is acquired.

Resolve mysterious actions

The gravity of a black hole captures problems that can get too close and tear it apart. For example, problems from captured stars spread to hot, bright, rapidly rotating discs called adherent discs. In the current idea, QPE is caused by objects interacting with this accretion disk (which could be stars or small black holes) and is linked to star destruction. However, there is no evidence that Ansky destroyed the stars.

The extraordinary nature of Ansky’s repeated bursts has led the researchers to consider other possibilities. Acceleration discs can be formed by gases captured by black holes from nearby areas, not by collapsed stars. In this scenario, X-ray flares are caused by small celestial objects that create a very energetic shock within the disk and repeatedly move and confuse the material that is circulating.

“Ansky’s X-ray burst is 10 times longer and 10 times brighter than what you would expect from a typical QPE,” says team member Joheen Chakraborty, PhD. Students at Massachusetts Institute of Technology, USA

“Each of these eruptions releases 100 times more energy than we have seen elsewhere. Ansky’s eruption also shows about 4.5 days, the longest rhythm ever observed.

Looking at a working black hole

Being able to see Ansky evolve in real time is an unprecedented opportunity for astronomers to learn more about black holes and the energetic events that empower them.

“In the case of QPE, we are still in a place where there are more models than data, and we need more observations to understand what is happening,” says Erwan Quintin, a research fellow at ESA and X-ray astronomer.

“We thought the QPE was captured by small celestial objects and spiraled down towards them. It seems Ansky’s eruption tells us another story. These repeated bursts could also be related to the gravity that ESA’s future mission Lisa could capture.”

“It is important to make these x-ray observations that complement gravitational wave data and help to solve the mysterious behavior of giant black holes.”