An international team of astronomers has captured the most detailed image yet of the core of the distant galaxy OJ 287, revealing a sharply curved plasma jet. The observation, made using a virtual telescope spanning multiple Earth diameters, supports the presence of two merging supermassive black holes at its heart. This breakthrough provides new insights into the extreme energies and structures around such cosmic phenomena.
For over 150 years, the galaxy OJ 287, located about five billion light years from Earth, has intrigued astronomers with its unusual brightness variations, suggesting two enormous black holes orbiting and merging at its center. Classified as a blazar, OJ 287 features a supermassive black hole that accretes matter and ejects powerful plasma jets filled with radiation, heat, magnetic fields, and particles.
Led by Dr. Efthalia Traianou of Heidelberg University, the team produced this unprecedented image by combining data from the 10-meter RadioAstron antenna on Russia's Spektr-R satellite with 27 ground-based observatories worldwide. This ground-space radio interferometer created a virtual telescope five times wider than Earth's diameter, achieving extraordinary resolution through interferometry that measures overlapping light waves.
The resulting image exposes a ribbon-like, sharply bent jet structure streaming from the galaxy's core, with some regions reaching temperatures of ten trillion degrees Kelvin. Researchers also identified a new shock wave colliding along the jet, connected to a 2017 gamma-ray signal with trillion-electron-volt energies. "We have never before observed a structure in the OJ 287 galaxy at the level of detail seen in the new image," said Dr. Traianou, a postdoctoral researcher with Dr. Roman Gold at Heidelberg University's Interdisciplinary Center for Scientific Computing.
These findings bolster the hypothesis of a binary supermassive black hole system and reveal how such black holes shape plasma jets. "Its special properties make the galaxy an ideal candidate for further research into merging black holes and the associated gravitational waves," Traianou stated. The study, involving institutions from Germany, Italy, Russia, Spain, South Korea, and the US, was published in Astronomy & Astrophysics.