Astronomers spot radio black hole trio inside merging galaxies

Rare Galaxy Merger Reveals Trio of Radio Active Black Holes (Image: Canva)

Researchers on Tuesday reported astronomers have identified a rare triple black hole system. The discovery involves three merging galaxies, each hosting active supermassive black holes. The study, published in The Astrophysical Journal Letters, details radio observations confirming the finding. Scientists say the system offers new insight into galaxy growth and black hole evolution.

What astronomers found in a rare triple galaxy system

The system is known as J1218/1219+1035 and lies far away. It is located roughly 1.2 billion light years from Earth. The system contains three interacting galaxies bound by gravity. Each galaxy hosts a supermassive black hole actively feeding. All three black holes shine brightly in radio wavelengths.

High resolution observations confirmed the unusual nature of the system. Astronomers used the National Science Foundation Very Large Array. They also used the Very Long Baseline Array for confirmation. The instruments detected compact radio cores in all galaxies. These radio signals indicate actively accreting black holes. Scientists classify such objects as active galactic nuclei.

The three galaxies are caught during an ongoing merger. Their central regions are separated by tens of thousands light years. Tidal features show strong gravitational interactions between them. Researchers say such systems are predicted by galaxy evolution theory. However, direct observations remain extremely rare.

Optical grz images from DeCaLS alongside radio observations from the VLA showing the J1218/J1219+1035 system. (Image: Canva)

How radio observations confirmed active black holes

The system was first noticed using infrared data. NASA’s Wide field Infrared Survey Explorer identified unusual emission signatures. These hinted at hidden black holes inside interacting galaxies. Optical spectroscopy later confirmed activity in one galaxy. Another showed mixed signals that could mask an active nucleus.

The third galaxy remained uncertain using traditional observations. Clear confirmation came only from detailed radio imaging. Observations at 3, 10, and 15 gigahertz were crucial. Astronomers detected radio cores aligned with each galaxy. These signals confirmed all three black holes were active.

The radio spectra showed non thermal synchrotron emission signatures. Two galaxies displayed steep radio spectra typical of active nuclei. The third showed an even steeper spectrum suggesting jet activity. Very Long Baseline Array data supported these conclusions. The measurements ruled out star formation as the radio source.

Why the triple radio AGN matters

Researchers say this system is the first confirmed triple radio AGN. It is only the third known triple active nucleus system nearby. Dr Emma Schwartzman led the study from the Naval Research Laboratory. She said the discovery offers rare insight into galaxy mergers.

By observing three feeding black holes together, scientists can test theories. Galaxy collisions are thought to drive gas toward central regions. This process fuels black hole growth and jet activity. The system provides a natural laboratory for such studies.

Future observations are already planned by the research team. Near infrared imaging will map the galaxies’ tidal structures. X ray observations will examine high energy emissions from each nucleus. Scientists hope to build a complete picture of this rare system.

The discovery highlights the value of combining infrared and radio surveys. Researchers believe more hidden triple systems may exist. Expanded searches could reveal how black hole triplets shape galaxies.