Something unexpected has come to life in the great darkness of space. In a galaxy 300 million light-years away from Earth, a once-quiet black hole has woken up. Astronomers became aware of this galaxy in the Virgo constellation when it abruptly began to light up in December 2019.
For decades, the black hole at its centre had shown no activity. But then, without warning, it burst into light — a sign that something remarkable was happening.
A black hole that refused to stay quiet
The galaxy, named SDSS1335+0728 and nicknamed “Ansky,” first surprised scientists with its sudden brightness in 2019. Astronomers at the European Southern Observatory used NASA’s Swift and the eROSITA telescopes to study the event. Their early findings suggested that the galaxy’s central black hole had entered an active phase, possibly feeding on surrounding matter. But more surprises were on the way.
In February 2024, a team from Valparaiso University in Chile noticed new activity. Led by researcher Lorena Hernández-García, they observed powerful, repeating X-ray flares using telescopes like XMM-Newton, Chandra, NICER, and Swift. These flares, known as quasi-periodic eruptions (QPEs), had been seen in other galaxies before. Yet the ones from Ansky were far stronger — up to 100 times more energetic than usual — and each lasted over four days.
Unusual flares challenge old theories
The team’s findings were published in Nature Astronomy on 11 April, offering a rare glimpse of a black hole coming to life. “This is the first time we have observed such an event in a black hole that seems to be waking up,” Hernández-García said. “This rare event provides an opportunity for astronomers to observe a black hole’s behaviour in real time.”
These QPEs have forced scientists to rethink what causes such flares. Normally, they occur when a star is torn apart by a black hole, feeding its accretion disk. But in Ansky’s case, no sign of a shredded star was found. This suggests that something else is at play. One possibility is that a smaller object — like a star or mini black hole — is orbiting the central black hole and disrupting its disk. Another theory points to gravitational waves as the cause of the repeated flares.
Looking ahead to future discoveries
To solve the mystery, scientists hope to use future tools like the European Space Agency’s Laser Interferometer Space Antenna (LISA). Scheduled for launch in 2035, LISA could detect gravitational waves from these events with unmatched precision, possibly confirming their role in the eruptions.
Until then, Ansky continues to intrigue researchers. Its unusual X-ray flares offer a new window into black hole behaviour, one that challenges long-held beliefs. “Studying Ansky will help us to better understand black holes and how they evolve,” Hernández-García said.
This black hole, once quiet and overlooked, may now shape our understanding of the universe’s most powerful forces.
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