Astronomers detect 8 billion-year-old explosion – 10/20/2023 – Science

Astronomers have detected an intense burst of radio waves from what appears to be a galaxy merger dating back about 8 billion years, in the oldest recorded example of a phenomenon known as a “fast radio burst.”

The explosion, lasting less than a millisecond, released the amount of energy our Sun emits in three decades, the researchers said, and was detected by the Australian SKA Pathfinder, a radio telescope in the state of Western Australia. The location of the burst was pinpointed by the Very Large Telescope, at the European Southern Observatory, in Chile, one of the most powerful optical telescopes in the world.

A fast radio burst, or FRB, is a pulse of radiofrequency electromagnetic radiation.

“The radio waves in FRBs are similar to those used in microwave ovens. The amount of energy in this FRB is equivalent to microwaving a bowl of popcorn twice the size of the Sun,” said astronomer Ryan Shannon , from the Swinburne University of Technology, in Australia, co-leader of the study published this week in the journal Science.

Until now, the oldest known explosion of this type was 5 billion years old, a difference of 3 billion years. The universe is about 13.8 billion years old. For comparison, the Earth is about 4.5 billion years old.

By studying objects and events from long ago, astronomers observe across vast cosmic distances, which also makes this the most distant radio burst ever detected.

“We now know that fast radio bursts have existed for more than half the age of the universe,” said astronomer and study co-leader Stuart Ryder of Macquarie University in Australia.

Fast radio bursts were discovered in 2007.

“The most likely source is a hyper-magnetized neutron star, called a magnetar. These stars are stellar corpses with the mass of the Sun but the size of a small city. They are some of the most extreme objects in the universe, which would be necessary to produce such extreme explosions,” Shannon said.

“There are more energetic events in the universe, associated with stellar explosions or a black hole tearing a star apart. But FRBs are unique in that they produce all their energy in radio waves, with nothing seen in other bands — visible light or X-rays, for example—and the fact that the signals are so short,” he added.

They are also more common, according to Shannon, and it is believed that more than 100,000 occur daily somewhere in the universe. However, far fewer have been detected and only about 50 — including this one — have been traced back to the galaxy where they originated.

“Galaxies in the distant universe look different from nearby ones — they don’t have pretty spiral arms — so it wasn’t clear whether what we were seeing was a galaxy with some clusters or some smaller galaxies. It’s likely that some galaxies, possibly merging, be the source,” Shannon said.

The researchers said studying these explosions could also help detect and measure the immense amount of matter believed to populate the expanses of space between galaxies.