Black hole reawakens with intense, mysterious X-ray bursts

A black hole that had been silent for decades has erupted with brilliant flashes of X-ray light, surprising astronomers and opening a rare window into one of the universe’s most extreme phenomena.

The black hole, known as “Ansky,” sits at the heart of SDSS1335+0728 – a distant galaxy located 300 million light-years away in the constellation Virgo.

Scientists from the European Southern Observatory and Valparaíso University in Chile have been tracking the black hole’s activity, using X-ray telescopes to monitor its strange awakening.

The research is supported by XMM-Newton, an observatory operated by the European Space Agency. NASA is also contributing to this global collaboration with the NICER, Chandra, and Swift telescopes.

A black hole breaks its silence

Black holes, despite their reputation for devouring everything in sight, can actually go unnoticed for long periods. They lie dormant, consuming little to no matter from their surroundings.

This had been the case with the black hole at the center of SDSS1335+0728 – until late 2019. That’s when something changed. The galaxy began to shine unusually bright in optical light, prompting astronomers to dig into archival data and launch new observations.

Paula Sánchez Sáez is a researcher at the European Southern Observatory and leader of the team that first explored the black hole’s activation.

“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,” said Sánchez Sáez.

Now classified as an active galactic nucleus, or AGN, the black hole is producing intense bursts of X-rays that repeat at nearly regular intervals.

Witnessing a rare event

In February 2024, the story took a more fascinating turn. A team led by researchers from Valparaíso University began detecting consistent X-ray bursts from the black hole.

These flares are known as quasiperiodic eruptions (QPEs) – brief flashes of high-energy X-rays that appear and disappear in a pattern.

“This rare event provides an opportunity for astronomers to observe a black hole’s behavior in real time, using X-ray space telescopes XMM-Newton and NASA’s NICER, Chandra and Swift,” noted Lorena Hernández-García, a researcher at the Valparaiso University, Chile.

“QPEs are short-lived flaring events. And this is the first time we have observed such an event in a black hole that seems to be waking up.”

Detecting faint x-ray emissions

Quasiperiodic eruptions have only been seen a few times since their discovery, and no one fully understands what causes them.

“The first QPE episode was discovered in 2019, and since then we’ve only detected a handful more. We don’t yet understand what causes them. Studying Ansky will help us to better understand black holes and how they evolve,” said Hernández-García.

Among the many telescopes involved, XMM-Newton has proven to be especially valuable. Hernández-García noted that it is the only X-ray telescope sensitive enough to detect the fainter X-ray background light between the bursts.

“With XMM-Newton we could measure how dim Ansky gets, which enabled us to calculate how much energy Ansky releases when it lights up and starts flashing.”

What is causing the x-ray flashes?

Normally, when a black hole captures matter – such as gas or even a star – the material is shredded and forms a bright, spinning disc known as an accretion disc.

Some quasiperiodic eruptions are thought to be triggered by interactions between this disc and a nearby object like a small star or black hole. These interactions generate energy bursts detectable as X-rays.

However, Ansky doesn’t fit that model neatly. So far, there’s no sign it has destroyed a star. This led researchers to consider a different explanation: perhaps the black hole is collecting gas from its environment.

A small object might be disturbing this gas repeatedly as it orbits through it, creating periodic shocks that result in X-ray flashes.

Ansky challenges existing ideas

Joheen Chakraborty, a PhD student at the Massachusetts Institute of Technology, noted that the bursts of X-rays from this black hole are ten times longer and ten times more luminous than what we see from a typical quasiperiodic eruption.

“Each of these eruptions is releasing a hundred times more energy than we have seen elsewhere. Ansky’s eruptions also show the longest cadence ever observed, of about 4.5 days,” said Chakraborty.

“This pushes our models to their limits and challenges our existing ideas about how these X-ray flashes are being generated.”

Watching a black hole transform

What makes this situation so unique is that researchers are witnessing the black hole’s transformation in real time. Rather than catching the aftermath of some cosmic outburst, they’re watching the outburst as it happens.

“For QPEs, we’re still at the point where we have more models than data, and we need more observations to understand what’s happening,” said Erwan Quintin, an ESA research fellow and X-ray astronomer.

“We thought that QPEs were the result of small celestial objects being captured by much larger ones and spiraling down towards them. Ansky’s eruptions seem to be telling us a different story. These repetitive bursts are also likely associated with gravitational waves that ESA’s future mission LISA might be able to catch.”

According to Quintin, it is crucial to have these X-ray observations that will complement the gravitational wave data and help us solve the puzzling behavior of massive black holes.

Image Credit: European Space Agency

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–