Newly discovered cosmic radio bursts have some unique properties that provide scientists with important clues to the possible causes of these mysterious astronomical phenomena known as fast radio bursts (FRB).
At the same time, such features call into question what astronomers thought they knew about these powerful outbursts, as shown in a new study published in the journal. temper nature in this month.
First discovered in 2007, they are extremely bright pulses of radio waves that come from distant galaxies. In just a split second, they release the same amount of energy as the Sun does over the course of several days. In the past 15 years, about 800 FRBs have been observed, and this number is rising.
According to Kshitij Aggarwal, associate researcher at West Virginia University, in the US, when the telescope picks up the FRB, one of the most important features scientists examine is what’s called scattering, which is essentially a measure of how the FRB works. Stretched when it hits the ground.
“Plasma between stars and galaxies causes all light – including radio waves – to slow down, but lower frequencies feel this effect more strongly and slow down more than higher frequencies,” Aggarwal explained in a research paper published on the site. Conversation.
“FRBs have a range of frequencies, so light with a higher frequency in the explosion hits the Earth earlier than at lower frequencies, causing scattering,” said the researcher, who is one of the authors of the new study. “This allows scientists to use scattering to estimate how far away from the Earth the FRB originated. The more stretched the FRB, the more plasma the signal must pass through and the further away the source is.”
FRB190520 is a fast repeating radio burst
The new FRB was discovered by Aggarwal and his team called FRB190520. They found that it uses the Chinese 500m Aperture Spherical Telescope (FAST), also known as the “eyes of the sky.”
“One of the interesting things that we immediately noticed about FRB190520 is that it is one of only 24 FRBs that iterates, and it does a lot more than the others,” said Aggarwal. “Produced 75 bursts over a six-month period in 2020.”
The team then used observations from the state-of-the-art Very Large Array (VLA) radio telescope in New Mexico, USA, to study more about this FRB and successfully located its source – a dwarf galaxy about 3 billion away. .light years from Earth. “That’s when we started to realize how important this FRB is,” Aggarwal reported.
First, they found that a stable, albeit much weaker, radio signal was emitted by something from the same place as FRB190520. “Because we were able to determine that the FRB came from a dwarf galaxy, we were able to determine the exact distance of this galaxy from Earth. But this result is meaningless.”
To the researchers’ surprise, the distance estimate they made using FRB scattering was 30 billion light-years from Earth, a distance 10 times greater than the galaxy’s actual 3 billion light-years.
The astronomers were only able to determine the exact location – and therefore the distance from Earth – of 19 other FRBs. For the rest of the known FRBs, astronomers have to rely only on scattering to estimate their distance from our planet.
“For FRBs with known habitat locations, the estimated dispersal distances are very similar to the actual distances from their home galaxies,” explained Aggarwal. “But this new FRB shows that estimates using dispersion can sometimes be incorrect and throw a lot of assumptions out the window.”
This new discovery raises some questions, such as whether continuous radio signals are common, what conditions produce them, and whether the same phenomenon that produces FRBs is responsible for the emission of the continuous radio signal.
Moreover, according to Aggarwal, the reason why FRB190520 scattered is much greater than it should be a big mystery as well. “Was it due to something close to the FRB? Was it related to the continuous radio source? Did it have something to do with the material in the galaxy from which the FRB comes? All these questions have not been answered,” the researcher said, explaining that he and his team will focus on studying the phenomenon using a number of From different telescopes around the world.
“By studying FRB, its galaxy and the space environment around its source, we hope to find answers to many of the mysteries it has uncovered,” he said.
More answers may also come from further studies of this and other FRBs in the coming years. The larger the catalog of astronomers’ records, the greater the chances of discovering FRBs with exciting properties that could help unravel these fascinating astronomical phenomena.
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