Astronomers have revealed a rare “triple-double” radio galaxy located 7.5 billion light-years from Earth. Known as J022248−060934, this extraordinary system offers fresh insights into the behavior of supermassive black holes. With only six other galaxies of its kind previously known, this discovery pushes the boundaries of our understanding of cosmic phenomena and may pave the way for future studies into the evolution of galaxies and their central black holes.
Radio galaxies like J022248−060934 are powered by supermassive black holes that launch high-energy jets of particles into space. These jets interact with the surrounding gas, creating massive radio lobes that can be observed from Earth.
A Rare Cosmic Phenomenon: Triple-Double Radio Galaxy
Triple-double radio galaxies, or TDRGs, are an extremely rare subclass of radio galaxies. The name “triple-double” comes from the unusual configuration of three pairs of radio lobes, each formed during different bursts of activity from the black hole. This discovery, made using data from the MeerKAT International GigaHertz Tiered Extragalactic Exploration (MIGHTEE) survey, has only added to the intrigue of these cosmic objects.
Researchers believe that J022248−060934’s black hole has switched its activity on and off at least three times, creating three sets of radio lobes. These emissions, which stretch over 5 million light-years, classify the galaxy as a giant radio galaxy. “We found a very rapid duty cycle of 90% for the first active phase,” the researchers note in their paper. “This implies that the nuclear activity of the source is only interrupted for a short period.” This rapid duty cycle challenges previous models, which suggested longer periods of inactivity between active phases of black holes.
The Evolution of the Galaxy’s Radio Lobes
The study of the galaxy’s radio lobes offers clues to the age and evolution of its central black hole. Spectral aging analysis revealed that the outermost lobes, which formed during the first period of activity, are at least 16 million years old. This phase lasted for about 10 million years, followed by a quiet period of about 1 million years. The second active phase lasted around 7 million years, and the current, ongoing third phase has been active for roughly 8 million years. This timeline illustrates how the black hole’s activity has fluctuated over vast cosmic timescales.
The existence of multiple phases of activity provides a unique opportunity to study the “duty cycle” of supermassive black holes, the process through which they alternate between active and dormant states. The detailed study of these phases is crucial for understanding how black holes grow and influence the galaxies around them.
Radio continuum image of the TDRG showing its morphology as well as the position of its host galaxy, as indicated by the central cross. The three pairs of lobes are indicated by I (outermost), II (middle) and III (innermost). Credit: Monthly Notices of the Royal Astronomical Society (2026). DOI: 10.1093/mnras/stag378
New Discoveries on the Horizon
The discovery of J022248−060934, detailed in the Monthly Notices of the Royal Astronomical Society, is just the beginning. As technology advances, future radio telescopes such as the Square Kilometer Array Observatory are expected to uncover more TDRGs, which will expand our knowledge of these rare cosmic phenomena. “The advent of new radio telescopes such as the Square Kilometer Array Observatory or the upgrade of current telescopes to an unprecedented high sensitivity and resolution will allow systematic search and hopefully the discovery of more TDRGs,” the team concludes.
The ongoing development of next-generation telescopes will revolutionize our ability to detect and analyze these objects. By observing TDRGs, astronomers hope to learn more about how supermassive black holes impact their host galaxies and the broader universe.