They are called high-speed radio explosions or FRBs, and these strange, fleeting signals from space are shrouded in mystery. But thanks to Canada's largest radio telescope, astrophysicists are discovering more and more of them in their quest to find out what these objects are tickling.
The first FRB was discovered in 2007 by an astrophysicist and his student while passing 2001 data collected from the Parkes Observatory in New South Wales, Australia. Since then, dozens more have been discovered. Scientists have yet to learn what causes these signals.
But these short space-passing signals – and lasting only a millisecond or so – came as another surprise: some of them were repeated.
The first of these repeaters was discovered by McGill's PhD student Paul Scholz in 2015. The second was unveiled last January. And the list is getting longer.
In a new study, filed in the Astrophysical Journal Letters and pre-printed on arXiv.org, a group of Canadian scientists discovers that another eight recurring FRBs have been discovered by the Canadian Waterproof Intensity Telescope (CHIME).
The discoveries are an important step in better understanding what these powerful signals are generating and where they come from.
"The first biggest conclusion [from the paper] is that this is not an anomalous phenomenon. This is real, "said Victoria Kaspi, an astrophysicist at McGill University and the Canadian Institute for Advanced Research (CIFAR)." It just takes time and patience to find one. And two, it gives them the ability to localize them, which is huge in the FRB field. "
The CHIME instrument cannot be sensitive and accurate in its detection, which means that it cannot localize the signal. Instead, his job is to find as many as possible. Determining their exact position depends on the other telescopes.
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"Discovering eight sources like this is so important because it says that we have many more repeats of FRBs and can discern the environments and galaxies in which FRBs are located if we follow them with other telescopes," said Pragya Chawla, co-author of the paper and Ph.D. at the McGill Space Institute.
Of the ten recurring FRBs, only two have been found to their point of origin: one is in a dwarf galaxy and the other is in a spiral galaxy.
Multiple FRBs can be detected
FRBs are a hot topic in the astronomical world, mostly because they are a fairly new discovery and the responsible mechanism is not understood.
"We think we understand what's in the cosmos," Caspi said. "But fast radio poles were a total surprise. Nobody expected them. Nobody anticipated them. Indeed, technological advances have allowed us to see this. And I think it's really interesting that we're still learning very basic things about what's happening in space. . "
Because they release such intense energy, some theories suggest that the source is a neutron star, a small dense star left after a supernova. Another theory suggests that it could be a magnet, a star similar to a neutron star, but with an extremely strong magnetic field.
Although the known FRBs – both repeaters and apparent non-repeaters – are believed to originate in other galaxies, one of the newly discovered ones seems to be closer than the others, perhaps even within our own galaxy. However, Chawla said that if found inside our galaxy, "it would be very surprising.
"Because we know many neutron stars within our own galaxy that emit such impulses, but none have seen it get this far at the edge of our galaxy."
CHIME has been quite successful in finding these puzzling objects, but the even better news is that the telescope is not operating at full power: there is still a need for better calibration. Once this is done, it is expected to detect even more FRBs daily. And that means more information to give other astrophysicists the tools to unravel their mystery.
"I think the coming year will be really good for FRB," Caspi said. "Will we know the answer in a year? I don't know. I don't know. Maybe. But I think we'll make significant progress in a year."