A groundbreaking discovery in astrophysics has been made as astronomers have successfully captured a radio image showcasing two black holes orbiting each other for the first time. This remarkable achievement comes just six years after the unveiling of the first-ever photograph of a single black hole. The new findings confirm the long-suspected existence of pairs of supermassive black holes, a phenomenon scientists have theorized for decades but had never directly observed until now.
The binary black hole system is located at the heart of a luminous object known as quasar OJ 287, situated approximately 3.5 billion light-years from Earth. Quasars, a term derived from "quasi-stellar objects," represent the incredibly bright cores of distant galaxies, fueled by black holes that consume surrounding gas and dust. OJ 287 has been particularly notable due to its brightness variations, which cycle every 12 years. This pattern hinted at the possibility of two massive black holes engaging in a cosmic dance.
The recent observations are among the sharpest radio images ever captured, providing new insights into the intricate processes occurring deep within a quasar. The data suggests that both black holes might be generating their own powerful energy jets. The team, led by Mauri Valtonen from the University of Turku in Finland, utilized a sophisticated radio telescope system, which included the RadioAstron satellite, to achieve this groundbreaking image. In contrast to previous efforts relying solely on Earth-based telescopes, this innovative approach yielded superior image resolution.
Black holes remain one of the most enigmatic objects in the universe. They are regions of space where gravitational forces are so intense that nothing, not even light, can escape. Approximately 50 years ago, many astronomers were skeptical about the existence of these elusive giants. Today, however, black holes are widely accepted as real phenomena, with various advanced imaging techniques enabling their study, including the Event Horizon Telescope, which produced the first image of a black hole in 2019.
This new radio image is part of a comprehensive study on OJ 287, which has been published in The Astrophysical Journal. The host galaxy is believed to harbor one colossal black hole, roughly 18 billion times the mass of the Sun, accompanied by a smaller black hole weighing around 150 million solar masses. As the smaller black hole orbits its massive counterpart, it periodically disrupts the larger black hole’s disk of gas and dust, resulting in predictable bursts of light.
The initial indications of unusual activity in OJ 287 date back to the late 1800s, when the quasar unexpectedly appeared in early astronomical photographs—long before the concept of black holes was established. In the 1980s, Finnish astronomer Aimo Sillanpää identified its repeating brightness pattern and proposed the existence of two black holes. This hypothesis has since spurred a global effort to track and map the motion of the binary system.
The confirmation of this binary black hole system was made possible through an advanced radio telescope network, including the Russian RadioAstron satellite, which ceased operations in 2019. This satellite orbited approximately 120,000 miles from Earth, about halfway to the moon, allowing for an unprecedented level of detail when combined with ground-based radio dishes. This space-based technique offered a longer observational baseline, resulting in a higher-resolution image compared to previous methods.
Despite the advantages of the space-based approach, it is not without its challenges. The longer radio wavelengths used can blur as they travel through space, making it difficult to visualize the edges of a black hole. According to Daniel Reichart, a professor at the University of North Carolina and a co-author of the study, while the Event Horizon Telescope provides slightly lower resolution images, it offers higher fidelity and clearer representations. Nevertheless, this new technique allowed the team to distinguish between the two black holes in OJ 287—an achievement that would have been impossible without such high resolution.
For the first time, astronomers have successfully captured an image of two black holes in orbit around one another. Valtonen expressed the significance of this breakthrough, noting that while the black holes themselves are invisible, they can be detected through energetic particle jets and the luminous gas that surrounds them. Notably, the team also observed a twisting jet emanating from the smaller black hole, which appears to oscillate as it moves through its orbit. Future studies may provide even more insights into the behavior of these extraordinary cosmic entities.
