Fast radio bursts (FRBs) are brief, one-off powerful emissions of radio waves that come to us from far-away galaxies. Being such fleeting events, they have been difficult to spot and study directly. Now, new observations have almost doubled the number of known bursts.
Not even three dozen FRBs were known last year, but the new detection, published in Nature, adds 20 more events to the list, including the closest FRB and the most-energetic one ever detected. None of the bursts repeated themselves, unlike notorious FRB 121102, whose currently unique nature allowed researchers to find its origin.
This new work has an advantage over previous observations. It was conducted with a single observatory, so the detections were much easier to compare with each other. The team was able to understand more subtle relations at play in the emissions and confirmed that these events are clearly coming from far, far away.
“We’ve found 20 fast radio bursts in a year, almost doubling the number detected worldwide since they were discovered in 2007,” lead author Dr Ryan Shannon, from Swinburne University of Technology and the OzGrav ARC Centre of Excellence, said in a statement. “Using the new technology of the Australia Square Kilometre Array Pathfinder (ASKAP), we’ve also proved that fast radio bursts are coming from the other side of the Universe rather than from our own galactic neighbourhood.”
The light of FRBs travel across the universe and interact with clouds of gas scattered around intergalactic space. The researchers showed that different wavelengths of light are slowed down by different amounts. By timing the arrival, they can work out just how much matter there is between us and the source, or estimate a likely origin for the FRB.
This approach is not extremely precise yet, but it gives a good general idea. The closest one was estimated in this way to be originating from roughly 425 million light-years away, although based on where in the sky it is, the most likely source is actually 685 million light-years away. This is certainly a big difference, and the team now hopes to improve the source location significantly.
“We’ll be able to localize the bursts to better than a thousandth of a degree,” Dr Shannon added. “That’s about the width of a human hair seen ten metres [33 feet] away, and good enough to tie each burst to a particular galaxy.”
By understanding where these FRBs are coming from, the researchers hope to unravel the mystery of their origins.