New Technique Unveils Supermassive Black Hole Pairs

Bright flashes of lensed starlight guide the way to detecting elusive black hole binaries.

Published on Feb. 13, 2026

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Researchers at Oxford University and the Max Planck Institute propose a new method to detect supermassive black hole binaries using gravitational lensing. As the binary orbits, it produces repeating flashes of lensed starlight that can provide information about the black holes' properties and enable new studies. Current and upcoming wide-field surveys may detect these bursts in the future, allowing astronomers to identify inspiraling supermassive black hole binaries years before space-based gravitational wave detectors come online.

Why it matters

Supermassive black hole binaries play a crucial role in galaxy evolution and are among the most powerful sources of gravitational waves in the Universe. While future space-based observatories will be able to detect such binaries directly, this new technique offers the potential to identify them using existing and upcoming electromagnetic surveys, opening the door to multi-messenger studies of black holes and new tests of gravity and black hole physics.

The details

Black holes act as natural telescopes, bending light with their gravity and magnifying stars behind them through gravitational lensing. A supermassive black hole binary produces a rotating caustic curve that can sweep across a large volume of stars, leading to repeating bursts of lensed starlight. By measuring the timing and brightness of these flashes, astronomers can infer key properties of the underlying black hole binary, including its masses and orbital evolution.

  • The researchers' findings are published today in Physical Review Letters.

The players

Miguel Zumalacárregui

Researcher at the Max Planck Institute for Gravitational Physics.

Bence Kocsis

Co-author of the study and professor in the Department of Physics at the University of Oxford.

Hanxi Wang

PhD student in Bence Kocsis' group and lead author of the study.

Vera C. Rubin Observatory

A powerful wide-field survey that may be able to detect the repeating lensing bursts in the coming years.

Nancy Grace Roman Space Telescope

Another upcoming wide-field survey that may contribute to the detection of these elusive black hole binaries.

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What they’re saying

“Supermassive black holes act as natural telescopes. Because of their enormous mass and compact size, they strongly bend passing light. Starlight from the same host galaxy can be focused into extraordinarily bright images, a phenomenon known as gravitational lensing.”

— Miguel Zumalacárregui, Researcher, Max Planck Institute for Gravitational Physics (Mirage News)

“The chances of starlight being hugely amplified increase enormously for a binary compared to a single black hole.”

— Bence Kocsis, Co-author, University of Oxford Department of Physics (Mirage News)

“As the binary moves, the caustic curve rotates and changes shape, sweeping across a large volume of stars behind it. If a bright star lies within this region, it can produce an extraordinarily bright flash each time the caustic passes over it. This leads to repeating bursts of starlight, which provide a clear and distinctive signature of a supermassive black hole binary.”

— Hanxi Wang, Lead author, PhD student at University of Oxford (Mirage News)

What’s next

With powerful wide-field surveys like the Vera C. Rubin Observatory and the Nancy Grace Roman Space Telescope coming online in the near future, researchers are optimistic that these repeating lensing bursts could be observed, allowing astronomers to identify inspiraling supermassive black hole binaries years before future space-based gravitational wave detectors come online.

The takeaway

This new technique offers an exciting opportunity to detect elusive supermassive black hole binaries using existing and upcoming astronomical surveys, paving the way for true multi-messenger studies of these powerful cosmic objects and enabling new tests of gravity and black hole physics.