Galaxies can be separated by hundreds of thousands of light-years, but sometimes they merge. During such collisions, the supermassive black holes at the centers of these galaxies can become active when new streams of gas are funneled into their cores as a result of the merger.
For the first time, researchers reported the merger of three galaxies, during which all three supermassive black holes were simultaneously active and emitting radio waves.
The triple system, named J1218/1219+1035, is located 1.2 billion light-years away from Earth. The distance between the galactic cores, which contain the supermassive black holes, is between approximately 22,000 and 97,000 light-years.
What else did the scientists reveal?
Large spiral galaxies have grown in size through interactions with smaller companion galaxies. Large elliptical galaxies result from collisions between spiral galaxies. This is similar to how the Milky Way and Andromeda will merge in a few billion years. Meanwhile, the merger of three galaxies occurs much less frequently, according to IFLScience.
“Triple active galaxy systems like this one are incredibly rare, and observing one during a merger allows us to see how massive galaxies and their black holes come together,” said Dr. Emma Schwartzman from the U.S. Naval Research Laboratory, the lead author of the study.
Initial data about this intriguing system were obtained through infrared observations. Radio observations using the National Science Foundation’s Very Large Array (VLA) and the Very Long Baseline Array (VLBA) provided crucial insights into this rare phenomenon. These two observatories confirmed the first detection of three radio-emitting active galactic nuclei in the merging galaxy system.
Supermassive black holes can reach astonishing sizes, but the processes behind their growth are not fully understood. This collision could be one pathway for that growth. Studying this and other similar systems could provide insights into how these black holes evolve. The team plans further observations of the system in radio wavelengths and beyond.
The findings of the study were published in The Astrophysical Journal Letters.
