Ribbons in the sky: Space radio telescope reveals plasma jet in a supermassive black hole binary candidate

An international team of astronomers has captured one of the most detailed images yet of a spectacular, ribbon-like jet emerging from the heart of the distant active galaxy, OJ 287. Enabled by the RadioAstron space telescope in combination with a global network of radio observatories, this breakthrough sheds new light on the extreme environments surrounding supermassive black holes and the powerful jets they launch into space.

Located about 5 billion light-years from Earth, OJ 287 has long intrigued scientists for its dramatic bursts of light and enigmatic behavior. It is suspected to hold in its central region a binary system of two supermassive black holes with the total mass exceeding a billion Solar masses. Now, for the first time, researchers have peered into its core with high spatial resolution, revealing a sharply bent, continuous “ribbon” of plasma twisting and turning as it streams from the galaxy’s center.

The findings have been published in the scientific journal Astronomy & Astrophysics by researchers from across Spain, Germany, The Netherlands, South Korea, Italy, the United States, and Russia. Some of them have worked on the RadioAstron project since its inception. “I joined the project in 1979, before many of my co-authors were born,” says Prof. Leonid Gurvits of Delft University of Technology (The Netherlands), whose decades of expertise in space VLBI (Very Long Baseline Interferometry) and active galactic nuclei helped shape the study.

Huge virtual telescope

OJ 287 is one of the best places in the Universe to study how two gigantic black holes interact. Although black holes themselves are invisible, we can detect them because they pull in matter from their surroundings. As gas and dust spiral inward, they heat up and emit radiation that we can observe with telescopes.

The RadioAstron Space VLBI mission combined a spaceborne radio telescope with 27 ground-based radio telescopes worldwide in this study, creating a virtual telescope five times the diameter of Earth, thus achieving a resolution equivalent to reading a newspaper in New York from Delft. This remarkable clarity revealed not only the intricate ribbon shape but also regions within the jet hotter than 10 trillion Kelvin, signaling extreme energy and motion near the black hole.

The birth of a shock wave

Polarisation measurements showed the jet’s magnetic field aligned along its length, providing new clues about how such jets are launched and shaped. The team also witnessed the very first moments of the birth of a new shock wave in the jet, which later collided with a stationary shock, an event that coincided with the historic detection of trillion-electron-volt gamma rays from OJ 287 in early 2017. “We captured the birth of a jet component and watched it travel down this beautiful ribbon until it hit a shock wave and produced the most energetic gamma rays ever detected from this source,” explains first author Dr. Thalia Traianou from Heidelberg University.

Black Hole Binaries and Gravitational Waves

These striking jet observations may also offer clues to a much deeper mystery. OJ 287 has puzzled astronomers since the 1880s with unusual brightness variations that follow a mysterious ~60-year cycle, suggesting the presence of not one, but two supermassive black holes locked in orbit. The newly imaged jet structure supports this idea. If two massive black holes are orbiting each other in the galaxy’s core, their motion could periodically twist and reorient the jet. Such effects are now becoming detectable with highly accurate radio recordings. The observed twist also aligns with long-term wobbling seen in OJ 287’s jet, likely caused by precession driven by the same orbital motion.

OJ 287 is therefore a prime target for studying how binary supermassive black hole systems evolve and eventually merge. The mergers are expected to generate powerful gravitational waves. These ripples in spacetime can potentially be detected, in particular by the joint ESA and NASA flagship mission LISA (Laser Interferometer Space Antenna) scheduled to launch in 2035.

A glimpse of what's to come

While this study uses only radio observations, it lays important groundwork for multi-messenger astronomy. This is a new approach that combines signals such as electromagnetic radiation, gravitational waves, and neutrinos to explore the Universe in unprecedented detail. Future observations of OJ 287 and similar systems could provide both types of signals, offering a more complete picture of black hole mergers.

“One of the beautiful things about fundamental science is the unpredictability of its impact,” says Gurvits. “When electricity was discovered two hundred years ago, no one could have imagined how deeply it would shape modern society. It’s the same with our research: we don’t know when and what its effects will be. But that uncertainty is part of what makes fundamental science so exciting. That said, it is certain that this RadioAstron study is a prelude to the upcoming transformational discoveries in the new era of multi-messenger astronomy.”