Number of known sources of repeating radio signals in space doubles
Over the last 15 years or so, astronomers have detected hundreds of unexplained radio signals from space, which they call fast radio bursts (FRBs). Now a fresh look at radio telescope data has doubled the number of known sources, bringing us closer to solving the mystery.
Like many things in science, the name says it all – FRBs are bursts of radio signals that come and go extremely quickly, lasting mere milliseconds. Sometimes they seem to be one-hit wonders, while others repeat randomly or on predictable patterns. By monitoring these repeating signals, scientists have tracked some of them to 25 sources across the sky.
And now that number has been doubled, thanks to an international team of astronomers and CHIME, a radio telescope array that scans the entire Northern Hemisphere sky every day. Using new statistical tools, the team analyzed data that CHIME gathered between September 2019 and May 2021, to try to narrow down where detected FRBs were coming from, and if there was some overlap between signals that could be attributed to the same sources.
“We combed through the data to find every repeating source detected so far, including the less obvious ones,” said Ziggy Pleunis, first author of the study. “These new tools were essential for this study because we can now accurately calculate the probability that two or more bursts coming from similar locations are not just a coincidence. It should be very useful for similar research going forward.”
In doing so, the team has now discovered another 25 FRB sources, bringing the total known sources to 50. That doesn’t mean they know what those sources actually are – just that something in those 50 regions of the sky are producing multiple FRBs. But this extra data should go a long way towards unraveling the mystery.
“These new discoveries will allow the scientific community to study more repeating FRBs in fantastic detail across the full electromagnetic spectrum and help answer a major open question in the field: Do repeating and non-repeating FRBs originate from distinct populations?” said Aaron Pearlman, an author of the study.
In fact, one implication of the new data may be that there’s no such thing as a one-off FRB – only repeating bursts that we just haven’t observed long enough to see the encore. That does fit the MO of the current prime suspect in the mystery: magnetars, the extremely dense, highly magnetized remnants left over after stars go supernova. A few years ago a magnetar in our own Milky Way was spotted giving off suspiciously FRB-like radio signals.
More observations are needed, and this new batch of data should help with that.
The research was published in The Astrophysical Journal.
Source: McGill University