If we were around and could see the heart of the galaxy cluster Able 980 about 260 million years ago, we might have seen something truly spectacular.
The brightest galaxy in the cluster erupted as a result of the activity of its supermassive black hole, an event that would burst large bubbles of radio light into space.
These newly discovered bubbles, called radio lobes or radio galaxies, are the oldest of their kind we’ve ever seen, say astronomers led by Surajit Pal of Savitribai Phule Pune University in India.
In addition, a pair of younger lobes has been found. A second team of astronomers, led by Gopalkrishna of the University of Mumbai in India, tracked them down and detected a single parent galaxy, making the shared object a rare example of a double pair of lobes.
The galaxy’s supermassive black hole appears to have erupted episodically.
Because radio lobes can span millions of light-years, much larger than the galaxies from which they originate, they can affect the tenuous gas between galaxies.
Studying these structures can help us better understand this medium, as well as the recurring episodic activity of the supermassive black holes that create them.
Radio lobes are quite common in the universe. Even the Milky Way has radio lobes. They are created when a supermassive black hole has an active phase, absorbing matter from its surrounding space.
While most of the material falls onto the black hole, some is accelerated along the black hole’s outer magnetic field lines to its poles, where it is ejected into space by two jets traveling at a significant percentage of the speed of light. Is.
These jets hit space, where they expand into lobes that interact with the space medium. These lobes act like synchrotrons to accelerate electrons, producing radio emission.
The problem is that they erode much faster than our ability to detect them, and it’s rare to find examples older than 200 million years as we see them. However, such monuments can record valuable information about the conditions in which they were formed.
Paul and his colleagues hypothesized that one environment that might prolong their survival is the warm, comfortable atmosphere of a quiet, low-mass galaxy cluster.
Using the giant VHF radio telescope in India, they searched galaxy clusters for such an environment, and found one, Abell 980, located about 2 billion light-years away. There, they detected faint radio structures, lobes that may be 260 million years old, stretching 1.2 million light years across.
The next thing was to identify where the lobes came from.
In another paper, Krishna and his colleagues succeeded in locating the brightest galaxy in the cluster. Now, it can be found in the center of Abel 980; However, Krishna and his team showed that they were not always in this position. In about 260 million years, it moved 250,000 light-years from the point where it emitted its first pair of lobes.
Once at the center of the cluster, the galaxy exploded again, creating a second pair of lobes. Astronomers have, to date, found only a few dozen examples of galaxies that are associated with two pairs of radio lobes, called double double radio galaxies.
Because the parent galaxies of the two pairs in Abel 980 have migrated, separating the lobes, Krishna and his team call these galaxies “detached double-double radio galaxies.” It is even rarer than double-radius galaxies. Only two other candidates have been reported, the researchers say, making the discovery the most plausible example yet.
More sensitive radio observations in the future may provide even more examples, which will help shed light on the recurring nature of supermassive black hole explosions.
