Black holes are perhaps the most mysterious and captivating objects in the cosmos. They warp space, distort time, and exert a gravitational pull so intense that nothing—not even light—can escape their grasp. While popular culture often imagines black holes as insatiable cosmic vacuums endlessly devouring stars and gas, reality paints a more nuanced picture. These gravitational titans often lie dormant for millions of years, quietly waiting. But when they wake, they do so with breathtaking force.
That is exactly what astronomers witnessed in the quiet galaxy SDSS1335+0728, located 300 million light-years away in the constellation Virgo. For decades, its central black hole had been silent. Then, like a cosmic leviathan stirring from slumber, it began to flash with powerful bursts of X-rays—signaling that something extraordinary was unfolding in its core.
Welcome to the story of Ansky, a newly active galactic nucleus that is rewriting what we thought we knew about supermassive black holes and their chaotic outbursts.
The Silent Galaxy That Spoke
Until recently, SDSS1335+0728 was, by all accounts, a galactic wallflower. Its central black hole, millions of times the mass of our sun, was invisible—an expected yet unassuming feature, dormant and undetectable. Then, in late 2019, something changed.
The galaxy suddenly began to shine with unexpected optical brightness. It was a flicker—a cosmic whisper that something beneath the surface had changed. Astronomers took notice, and soon telescopes around the world turned their gaze toward this once-silent system.
“We named it Ansky, short for ‘active nucleus of SDSS1335+0728,'” said Paula Sánchez Sáez of the European Southern Observatory in Germany, who led the initial investigation. “At first, we didn’t see any X-ray emissions, which made it even more puzzling. It just didn’t behave the way active galactic nuclei are supposed to.”
Archived data from the eROSITA X-ray telescope offered no clues. Ansky was shining optically, but the high-energy X-ray signature expected from an active black hole was mysteriously absent.
Until 2024.
A Monster Awakens: The Rise of the X-Ray Flashes
In February 2024, Lorena Hernández-García and her team at Valparaiso University in Chile picked up something stunning—Ansky had begun emitting bursts of high-energy X-rays at nearly regular intervals. These weren’t random flickers. They were rhythmic, intense, and entirely unlike anything previously observed from this galaxy.
This rare celestial behavior is known as a quasiperiodic eruption, or QPE. QPEs are short-lived but repeating flares of X-ray light, thought to originate from the region surrounding a supermassive black hole. Until recently, they had only been detected in a handful of galaxies, and their origin remains one of astrophysics’ juiciest open questions.
“This is the first time we’ve seen QPE-like behavior from a black hole that seems to be waking up for the first time,” Hernández-García explains. “It’s like watching the engine of a cosmic monster slowly start to rumble to life.”
What Are Quasiperiodic Eruptions, Really?
The leading theory is that QPEs are the result of small celestial bodies—perhaps stars or even rogue planets—being shredded or disrupted as they stray too close to the black hole’s event horizon. As the matter spirals inward, it forms a hot, glowing accretion disk that radiates intense energy, especially in X-rays.
But Ansky is challenging those assumptions. There’s no evidence that it recently destroyed a star, nor are its QPEs like the others we’ve seen.
Joheen Chakraborty, a Ph.D. candidate at MIT and part of the team monitoring Ansky, is intrigued. “Each X-ray eruption from Ansky is ten times longer and ten times more luminous than what we usually observe. The cadence between eruptions is also the longest we’ve seen—about 4.5 days.”
That cadence is crucial. It suggests that whatever is triggering the eruptions is moving on a consistent orbital path—possibly a smaller object plowing through the accretion disk, stirring up shockwaves as it goes.
“This kind of regularity pushes our theoretical models to the breaking point,” says Chakraborty. “It’s like we’re watching a dance between two cosmic partners—but we don’t know what the smaller partner is yet.”
The Power of Real-Time Observation
Studying black holes is normally an exercise in patience. Their activity plays out over eons, and most of what we know comes from historical data and statistical trends. Ansky, however, is offering a real-time look into the behavior of a supermassive black hole waking up from dormancy—a cosmic event of staggering rarity.
“With telescopes like XMM-Newton, NICER, Chandra, and Swift, we’ve been able to monitor Ansky across multiple wavelengths,” says Erwan Quintin, an ESA X-ray astronomer. “XMM-Newton in particular was critical because it’s sensitive enough to measure the dim X-ray background between bursts. That allows us to calculate the total energy output with unprecedented precision.”
The hope is that these observations will help scientists understand not just QPEs, but the fundamental processes that drive galactic nuclei as they evolve from dormancy into active states.
A Gateway to Gravitational Waves?
Ansky may also hold the key to understanding something even more exotic—gravitational waves. These ripples in the fabric of spacetime were first detected in 2015, confirming another one of Einstein’s predictions. They’re usually caused by massive objects like black holes or neutron stars colliding.
But repetitive, violent disruptions like Ansky’s X-ray bursts may also generate detectable gravitational waves—subtler, but equally valuable.
“With ESA’s upcoming LISA mission, which is designed to detect low-frequency gravitational waves, we might be able to pick up the signal from systems like Ansky,” Quintin suggests. “Imagine matching a gravitational wave to an X-ray flare and confirming, beyond doubt, that we’re watching a black hole in action. That’s the dream.”
A New Chapter in Black Hole Science
Ansky is more than just an interesting outlier. It is a live laboratory for studying one of the universe’s most extreme phenomena. And perhaps more importantly, it reminds us that even after a century of studying black holes, surprises still await us.
Astrophysicists are now racing to build new models, tweak existing simulations, and prepare for a future where Ansky and objects like it can be observed not only with light, but with gravitational waves and even neutrino detectors.
“We are entering a new era of multi-messenger astronomy,” Hernández-García says. “And Ansky is one of the clearest signals yet that the universe still holds secrets we’re only beginning to uncover.”
The Bigger Picture
Why do we care about a black hole 300 million light-years away? Because understanding how black holes evolve, flare, and interact with their surroundings can unlock deeper insights into the life cycle of galaxies—including our own Milky Way.
Ansky is a reminder that black holes aren’t just the end of the story. They’re dynamic, powerful engines of transformation that can shape galaxies, light up the cosmos, and challenge everything we thought we knew.
And now, thanks to Ansky’s awakening, we get to watch one of these sleeping giants come to life. In real time. In X-ray flashes that echo across the void of space.
The universe, it seems, still has much to say. And it’s up to us to keep listening.
Reference: Discovery of extreme Quasi-Periodic Eruptions in a newly accreting massive black hole, Nature Astronomy (2025). DOI: 10.1038/s41550-025-02523-9