One of the biggest mysteries in the universe is getting closer to the answers. Amazing eight new recurring radio signals, known as fast radio bursts (FRBs), are being ejected from deep space.
In early 2019, it was known that only one of these mysterious signals, FRB 121102, was flashing repeatedly. In January, scientists reported a second iteration (FRB 180814).
This new paper – Available on the arXiv Preprint Server and accepted at Astrophysical Journals – Describes eight new repeating signals detected by the Canadian Hydrogen Intensity Mapping Experiment (CHIME).
This leads to a known total number of repeating FRBs of 10. This means that we are beginning to build a statistical database of repeaters that can help astronomers understand what these signals actually are.
Fast radio bursts are certainly disturbing. They are detected as spikes in radio data that last only a few milliseconds. But in the meantime, they can emit more than 500 million suns.
Most FRBs are only detected once and cannot be predicted, so tracking them to their source is really difficult (although, as shown earlier this year for the first time, it is not impossible).
This is why repeaters are so important. And the news that they are not as rare as we thought means that it may be possible to trace more to their galaxy sources and determine what kind of environment they come from.
We can also start looking for similarities and differences between recurring FRBs.
"There are definitely differences between the sources, some of them more fruitful than others," said physicist Ziggy Pleunis of McGill University at ScienceAlert.
"From FRB 121102 we have already learned that bursts can be very clustered: sometimes the source does not burst for hours and hours and then you suddenly get multiple bursts in a short time. For FRB 180916 we watched the same. in this document. "
On the other side of the scale, six of the FRBs reported in the newspaper are repeated only once and the longest pause between signals is over 20 hours. The eighth (FRB 181119) is repeated twice after the initial detection, with a total of three pings.
We still don't know what that means, but it could indicate – as hypothesized in last month's article Harvard-Smithsonian 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, you may think that a volcano is in a state of sleep because it has not erupted long ago," said Pleunis.
But there are similarities between the Fed. The individual bursts of repeaters seem to last a little longer than the bursts of disposable FRBs. That's pretty interesting.
There is also frequency drift. The first two repeaters – FRB 121102 and FRB 180814 – showed a decrease in frequency, with each burst becoming consistently lower. Consider the sad sound effect of the trombone.
Most of the eight new repeaters also showed this decrease in frequency. This may be a clue as to what produces the signals.
"I just think it's so incredible that nature produces something like that," Pleunis said. "I also think there is a lot of important information in this structure that we just have to figure out how to code and it was a lot of fun trying to figure out what that was."
CHIME is optimized for the observation of a very wide range of skies in a lower frequency range than radio telescopes such as ASKAP or the Parkes Observatory in Australia, which have also discovered FRBs.
So far, the CHIME approach has proven to be extremely effective at detection. In addition to these repeaters and the repeater announced in January, CHIME has also detected a number of one-off bursts. However, it is not optimized to track these findings to source.
This is where the wider scientific community comes from. Just today, a different team of researchers, including Ravi, announced that they had made the advance of locating eight new repeaters in known galaxies, based solely on the direction from which the signals came.
Even roughly, we can say how far outbursts may have originated based on how dispersed the signal is – the higher these measures are, the further the distance is.
In fact, it becomes intriguing here because one of the signals, FRB 180916, has the lowest observed variance so far, indicating that it may be nearby.
"Even with the largest telescopes, if it is closer to you, you always get a better view than if it is something further away," astronomer Keith Banister of the Australian National Science Agency, CSIRO, told ScienceAlert participated in the research.
"So this particular low dispersion measure was super exciting because there is a good chance that it will be nearby. And that means we will be easier to see once we really know exactly where it is in the sky."
Signal polarization (how twisted the signal is) is also informative. If the signal is really twisted up, it means that it comes from an extreme magnetic environment, such as can be found around a black hole or a neutron star. Here is 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 recurring FRBs come from extreme environments.
We still don't know what that means. We do not know if there are several different classes of objects or events producing these signals. We do not know if they are all repeated or why they are repeated. But these results bring us closer to finally having some answers.
"I think (and I hope!) The document will encourage other astronomers to point their telescopes at these newly discovered sources," Pleunis said.
"Then there's a lot of information here that model designers can work with. I think this will help them understand what recurring FRBs produce.
"I also think our findings will influence the search strategy of other teams trying to find repetitive FRBs."
The study is accepted The Astrophysical Journal and is available on arXiv.