doi.org/10.1093/mnras/stag291
Credibility: 989
#black holes
About 500 million light-years from Earth, a bright galaxy called Mrk 501 may be about to offer us a rare spectacle: the collision of two supermassive black holes on a timescale that humans can still track, possibly in less than a century
This galaxy is a special type called a blazar, in which a supermassive black hole at the center ejects jets of matter at speeds close to that of light, pointed almost directly at us.
A recent analysis of high-resolution radio observations taken over 23 years has revealed something surprising: The strange behavior of light and jets suggests that there are not just one, but two supermassive black holes at the galaxy’s core, each driving its own jet.
The astronomers, led by Silke Britzen, from the Max Planck Institute for Radio Astronomy in Germany, observed that the main jet shows complex movements, as if it were oscillating, and identified signs of a second, weaker jet that appears to rotate around the center.
These patterns are best explained by the presence of a pair of black holes orbiting each other.
One of the periods of variation observed is about seven years, compatible with an oscillation in the system, while another, of approximately 121 days, may correspond to the orbital time of the two objects.
The distance between them would be extremely small for such gigantic objects – somewhere between 250 and 540 times the distance from Earth to the Sun, or less than 0.003 parsecs.
This puts them very close, overcoming a challenge known as the “final parsec problem”, in which black holes should be “trapped” in orbit without being able to get any closer.
If this discovery is confirmed, it would help to understand how these cosmic monsters, with masses millions to billions of times that of the Sun, manage to grow so much over time, probably through mergers.
Supermassive black holes exist at the centers of most large galaxies, and when galaxies collide, their central black holes are also attracted to each other.
In the case of Mrk 501, the pair is so close that merger could occur within a few decades.
Although it is not yet a definitive detection – as direct images of the two jets were not possible – this is currently the most convincing explanation for what radio telescopes have been recording.
Scientists will continue to monitor the galaxy closely, because if the black holes do collide, it would represent the first opportunity to observe the merger of supermassive black holes live, an event that releases immense energy and helps unlock mysteries about the evolution of galaxies and the Universe.
It’s a fascinating reminder of how the cosmos still holds surprises very close to us, in astronomical terms.
Published in 04/10/2026 03h30
Text adapted by AI (Grok) and translated via Google API in the English version. Images from public image libraries or credits in the caption. Information about DOI, author and institution can be found in the body of the article.
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