Researchers led by Mauri Valtonen published a radio image on October 9, 2025, that appears to resolve two supermassive black holes orbiting in quasar OJ 287, about 5 billion light-years away. The system shows a roughly 12-year cycle; the primary black hole is estimated at ~18 billion solar masses and the companion at ~150 million. While the image matches long-standing theoretical predictions and timing data, scientists caution overlapping jet structures could still mimic two sources until higher-resolution follow-up confirms the pair.
Historic First: Radio Image Appears to Resolve Two Supermassive Black Holes Orbiting in OJ 287
Researchers led by Mauri Valtonen published a radio image on October 9, 2025, that appears to resolve two supermassive black holes orbiting in quasar OJ 287, about 5 billion light-years away. The system shows a roughly 12-year cycle; the primary black hole is estimated at ~18 billion solar masses and the companion at ~150 million. While the image matches long-standing theoretical predictions and timing data, scientists caution overlapping jet structures could still mimic two sources until higher-resolution follow-up confirms the pair.
02:57, 05.11.2025Science
Historic Radio Image Shows Two Supermassive Black Holes in Orbit
What happened: For the first time, astronomers have produced a direct radio image that appears to resolve two supermassive black holes orbiting one another. The result, led by Mauri Valtonen of the University of Turku, was published on October 9, 2025, in The Astrophysical Journal. The observation targets the quasar OJ 287, located roughly 5 billion light-years away in the constellation Cancer, which displays a roughly 12-year brightness cycle.
Why this matters
This direct visual evidence bridges a long-standing gap between theoretical models, timing observations and gravitational-wave detections. Until now, most confirmed binary black hole systems were identified indirectly—through periodic brightness changes or by detecting mergers via gravitational waves (e.g., with LIGO and other observatories). A resolved image of two supermassive black holes orbiting each other provides a powerful new testbed for models of black hole growth, jet formation and relativistic orbital dynamics.
How the image was made
Valtonen's team used a global array of radio telescopes, including the Russian RadioAstron satellite, to achieve the extreme angular resolution required to separate the two components. The radio map reveals two distinct radio sources consistent with the expected locations of jets from each black hole.
Key measurements
Analysis indicates a very massive primary black hole of about 18 billion solar masses and a secondary of roughly 150 million solar masses. The lighter companion appears to drive a high-energy jet that traces a spiral-like structure and moves at relativistic speeds. These properties align with longstanding models for OJ 287 in which a smaller black hole orbits and periodically interacts with the larger object's accretion disc, producing recurring flares.
Remaining uncertainties and next steps
The researchers are careful to note that alternative explanations have not been completely ruled out. In particular, complex or overlapping jet structures from a single black hole could potentially mimic two separate components in the current data. Higher-resolution follow-up observations, ideally at multiple radio frequencies and with complementary imaging at other wavelengths, will be needed to confirm that both components are distinct black holes and to refine orbital parameters.
Bottom line: The new radio image is an unprecedented and compelling piece of evidence for a bound pair of supermassive black holes in OJ 287. If confirmed by further observations, it will deepen our understanding of black hole mergers, jet physics and gravitational dynamics in extreme regimes.
Note: This discovery synthesizes a century of timing observations, theoretical work and modern high-resolution radio astronomy to produce one of the clearest candidate images of a supermassive black hole binary to date.