A star's violent death revealed a hidden supermassive black hole.
Astronomers detected an inactive supermassive black hole wandering far outside its galaxy's center after it shredded a star that passed too close.
University of Maryland astronomers have detected an inactive supermassive black hole located far from the center of its host galaxy. This discovery marks the first time scientists have found an inactive black hole at such a great distance from a galactic center.
Because the black hole is not actively consuming matter, it should have remained invisible—yet its location was revealed when it tore apart a passing star, producing a brief but powerful flash of light. The findings were published on July 27, 2026, in The Astrophysical Journal Letters.
"This is a new result. What's new is that until now, we proceeded under the assumption that supermassive black holes are found at the centers of large galaxies," said study co-author Suvi Gezari, an associate professor of astronomy at the University of Maryland. "This discovery will have a major impact. It means we will find many more examples of wandering black holes and be able to understand how galaxies and their black holes merge and form over time."
A Long-Predicted Wandering Black Hole
Bilim insanları uzun zamandır, bazı kara deliklerin galaktik çarpışmalar ve birleşmeler sırasında galaksilerin dış bölgelerine doğru yer değiştirebileceğini öngörüyorlardı. Bu nesneler genellikle gezgin kara delikler olarak tanımlanırken onları bulmaksa son derece zor. Birçoğu hareketsizdir, yani yakındaki maddeleri tüketmiyor veya tespit edilebilir ışık üretmiyorlar. Sonuç olarak, Dünya'daki teleskoplar tarafından fark edilmeden galaktik sınır bölgelerinden geçebilirler.
Araştırmacılar, çalışmanın baş yazarı Robert David Stein'e göre "tüm evreni araştıran" Zwicky Geçici Tesisi (ZTF) kullanarak ilk kez bu durgun kara deliği tespit etti. Stein, UMD'nin Astronomi ve Fizik Bölümleri ile NASA'nın Goddard Uzay Uçuş Merkezi (GSFC) arasındaki bir araştırma ortaklığı olan Ortak Uzay Bilimleri Enstitüsü'nde Neil Gehrels Ödülü Doktora Sonrası Araştırma Görevlisidir.
Yapay Zeka Olağanüstü Bir Parıltı Keşfetti
Kaliforniya'nın San Diego bölgesindeki Palomar Gözlemevi'nde bulunan iki teleskopu kullanan ZTF, her iki günde bir tüm kuzey gökyüzünü inceliyor. Gözlemevinin her gece yüz binlerce değişen göksel olayı kaydetmesi, araştırmacıların her olayı tek tek inceleyerek kara delik belirtileri aramalarını imkansız hale getiriyor.
To process this immense volume of data, the team created an artificial intelligence (AI) program trained to recognize the distinctive light pattern produced when a black hole destroys a star. Known as a tidal disruption event, this phenomenon occurs when a star passes close enough to a black hole to be shredded by its gravitational force, and astronomers have documented many tidal disruption events near the centers of galaxies. The new AI system was designed to search the entire sky for the same type of flares, including locations far from galactic centers.
UMD researchers began running the program in August 2025. Just three months later, they detected the event that led them to the wandering black hole.
"I remember the moment we discovered it very clearly. It was a Saturday, and everyone was extremely excited, messaging each other. We dropped everything and started running all kinds of other instruments to get more data," said Stein. "We weren't sure we would succeed this quickly, so finding one this fast is incredible."
A Supermassive Black Hole Far from the Galactic Center
The black hole is located 9.3 kiloparsecs (about 30,000 light-years) from the center of its galaxy, and its mass is comparable to that of the supermassive black hole at the center of the Milky Way.
According to study co-author and UMD Astronomy Professor Sylvain Veilleux, what makes this object particularly surprising is the absence of a visible galaxy surrounding it.
"I'm surprised that such a massive black hole exists outside a galaxy," he said. "There should have been a Milky Way-like object around it, and that is definitely not the case."
Researchers believe the black hole's unusual position is likely linked to a past collision between galaxies.
One explanation is that a large galaxy swallowed up a smaller companion galaxy. Over time, the larger galaxy may have destroyed nearly all of the smaller galaxy's stars, leaving behind only its dense central core and its black hole, while another possibility involves a more chaotic encounter among three black holes. A galaxy may already have two black holes orbiting close to each other at its center, a system called a binary black hole system. If a third black hole appears during another galactic merger, the resulting three-body interaction may have ejected the smallest black hole from the center.
Additional observations of the tidal disruption event could help researchers determine which explanation is more likely.
Dormant Black Holes May Be Common
Understanding inactive black holes is important because most known black holes, including the one at the center of the Milky Way, are dormant.
Scientists do not yet know whether there are black holes wandering the outer regions of our galaxy. However, Stein said there is no need to worry about encountering one.
"At least within our lifetime, our chances of encountering one are very low."
As the research team continues searching for additional black holes drifting across the sky, according to Stein, finding more black holes could help scientists understand "how galaxies form and how many black holes are wandering around." This discovery also demonstrates that these hard-to-find objects can be identified through a combination of traditional sky surveys and machine learning, rather than relying solely on more expensive observation methods.
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