One of the biggest mysteries in the universe is getting closer and closer to answers. Amazing eight new repetitive radio signals, known as Fast Radio Bursts (FRBs), were discovered from outer space.
At the beginning of 2019, only one of these mysterious signals, FRB 121102, flashed repeatedly. In January scientists reported a second recurrence (FRB 180814).
This new paper, available on the preprint server arXiv and accepted in The Astrophysical Journal Letters describes eight new repeat signals that were discovered by Canadian radio telescope CHIME (Hydrogen Intensity Mapping Experiment).
This brings the known total number of repeating FRBs to 10. We begin by building a statistical database of repeaters that could help astronomers find out what those signals actually are.
Fast radio bursts are certainly confusing. They are detected as spikes in wireless data that take only a few milliseconds. During this time, however, they can release more energy than 500 million suns.
Most FRBs are discovered only once and can not be predicted. Therefore, for the first time, it is not impossible to trace them back to their source (although this has already been demonstrated earlier this year).
That's why repeaters are so important. And the news that they are not as rare as we thought means that it could be possible to trace more back to their source galaxies and determine from which environments they came.
We can also look for similarities and differences between repeating FRBs.
"There is definitely a difference between the sources, with some being more productive than others," physicist Ziggy Pleunis of McGill University told ScienceAlert.
"We already knew from FRB 1
On the other side of the scale, six of the FRBs reported in the publication repeated themselves only once, and the longest pause between the signals was more than 20 hours. The eighth (FRB 181119) repeated twice after the first discovery and pinged three times altogether.
We do not yet know what that means, but it might suggest – as suggested in a Harvard-Smithsonian article last month Astrophysicist Vikram Ravi – that all FRBs are actually repeaters, but some are much more active than others.
"Just as some volcanoes are more active than others and one can think that a volcano is slumbering because it has not erupted in a long time," noted Pleunis.
But there are also similarities between FRBs. The individual bursts of repeaters seem to take a little longer than the bursts of unique FRBs. That's pretty interesting.
There is also the frequency drift. The first two repeaters – FRB 121102 and FRB 180814 – showed a downward drift in frequency, with each burst gradually decreasing. Think of a sad trumpet sound.
Most of the eight new repeaters also showed this downward drift. This could be an indication of what the signals are producing.
"I just think it's so amazing that nature produces something like that," said Pleunis. "Besides, I think that this structure contains some very important information that we just have to encode, and it's been a lot of fun figuring out what that is."
So far, CHIME's approach to detection has proven to be remarkably effective at monitoring a very wide range of sky over a lower frequency range than radio telescopes such as ASKAP or the Parkes Observatory in Australia. In addition to these repeaters and the repeater announced in January, CHIME has also detected a number of unique bursts. However, it is not optimized for tracing these detections to a source.
This is exactly where the broader scientific community comes in. Just today another research team, including Ravi, announced that they had made progress in locating the eight new repeaters for known galaxies, based on the direction from which the signals came.  We can even roughly tell from the scatter of the signal how far away the bursts were – the higher these measures, the farther the distance. In fact, it becomes intriguing here because one of the signals in FRB 180916 is the lowest scatter, suggesting that it could be located nearby.
"Even with the largest telescopes, you can always get a better view if it's closer to you than if it's further away," says astronomer Keith Bannister of the Australian National Science Agency CSIRO, who is not involved in the research ScienceAlert:
said, "This very low dispersion measurement was so exciting because there is a good chance that it will be around, and that means it's easier to see if we really know exactly where it is in the sky. "
The polarization of the signals (how twisted the signal is) is also informative. If the signal is really twisted, it means that it comes from an extremely magnetic environment, such as a black hole or a neutron star. Such was the signal from FRB 121102.
But the team was able to measure the polarization of one of the new signals, FRB 180916, and it was really low. This tells us that not all repeating FRBs come from extreme environments.
We do not yet know what that means. We do not know if there are different classes of objects or events that produce these signals. We do not know if they all repeat themselves or why they repeat themselves. But these results bring us in a stunning way to the final answer.
"I think (and I hope!) That the paper will cause other astronomers to focus their telescopes on these newly discovered sources," said Pleunis.
Then there is a lot of information that modellers can work with. I think it will help them figure out what leads to repetitive FRBs.
"In addition, I think our results will influence the search strategy of other teams trying to discover repeating FRBs."
The research was included in The Astrophysical Journal and is available on arXiv ,