Published: Fri, January 11, 2019
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Mysterious repeating radio bursts baffle physicists

Mysterious repeating radio bursts baffle physicists

A Canadian-led team of astronomers has observed unusual repeating radio waves coming from deep space for just the second time ever. They could be the result of magnetars, or rapidly spinning neutron stars that have been strongly magnetized. Most of the FRBs previously detected had been found at frequencies near 1400 MHz, well above the Canadian telescope's range of 400 MHz to 800 MHz.

"Whatever the source of these radio waves is, it's interesting to see how wide a range of frequencies it can produce", said CHIME team member Dr. Arun Naidu, a researcher at McGill University.

In 2017 Professor Loeb and Harvard colleague Manasvi Lingham proposed that FRBs could be leakage from planet-sized alien transmitters.

However, a new facility in Canada called CHIME has added a new piece to the puzzle by detecting a second source of repeat fast radio bursts, as well as multiple instances of single FRBs. The Canadian astronomers say they've found a second repeating signal that is distinct from the first one. Some scientists had anxious that the range of frequencies it can pick up would be too low for it to receive the FRBs - but it found far more than expected, and scientists expect it to identify even more.

The repeating burst was among 13 fast radio bursts (FRB) recorded by a radio telescope located in B.C.'s Okanagan Valley. Only 60 FRB sources have been detected, including the 13 announced today.

Repeated bursts from one "fast radio burst" FRB were observed in the weeks following.

Some of the signal-scattering patterns suggest that the sources of the bursts have to be in special types of locations - for example, in supernova remnants, star-forming regions or around black holes. One FRB in particular, FRB 121102, is special because it's the only one that seems to be repeating its signal blasts on a regular basis.

Shriharsh Tendulkar, an astronomer from the McGill Space Institute and a co-author of the new study, said radio frequencies help scientists understand possible emission mechanisms, or processes, of FRBs, and also the effects that the radio waves encounter as they travel through space. Therefore, the signals have remained a mystery, with little evidence at all of where they might be coming from.

To process that, the team had to work out "how to scale the computations that are needed to do radio astronomy up to unprecedented volume". CHIME identified a fast radio burst with the lowest dispersion yet discovered, suggesting its source is the closest to Earth.

These events emit as much energy in one millisecond as the Sun emits in 10,000 years, but the physical phenomenon that causes them is unknown.

The new signals are likely to force scientists to reconsider current FRB models.

That high rate of discovery suggests that FBRs, let alone repeating FBRs, may not be as unique as we think, said Perimeter Institute faculty member Kendrick Smith. "This allows us to study how structures in the Universe formed and how they are distributed".

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