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Une Explosion Récemment Découverte Remet En Question Ce Que La

The newly discovered explosion challenges what science knows about fast radio bursts

A newly discovered cosmic radio burst with unique properties provides scientists with important clues to the possible causes of these mysterious astronomical phenomena known as fast radio bursts (FRBs).

Next, an optical, infrared and radio image of the field of FRB 20190520B. Credit: K. Aggarwal et al.

At the same time, such features challenge what astronomers thought they knew about these powerful outbursts, as shown in a new study published in the journal. nature During this month.

First discovered in 2007, they are extremely bright pulses of radio waves from distant galaxies. In just a split second, they release the same amount of energy as the sun for several days. Over the past 15 years, about 800 FRBs have been observed, and this number tends to increase more and more.

According to Kshitij Aggarwal, a researcher affiliated with West Virginia University in the USA, when the telescope captures the FRB, one of the most important features scientists look at is something called scattering, which is essentially a measure of how far the FRB will expand when it reaches Earth.

« Le plasma qui se trouve entre les étoiles et les galaxies ralentit toute la lumière – y compris les ondes radio -, mais les basses fréquences ressentent cet effet plus fortement et ralentissent plus que les haqusés ondes radio -, mais les basses fréquences ressent cet effet plus fortement et ralentissent plus que les haqusés ondes radio » Location. dialogue.

“FRBs have a range of frequencies, so high-frequency light from the explosion hits the Earth earlier than 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 from Earth the FRB is being generated. The longer the FRB is stretched, the more plasma the signal must pass through and the farther away the source is.”

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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 Radio Telescope (FAST), also known as the “Sky Eye”.

“One of the immediately interesting things we noticed about FRB190520 is that it’s one of only 24 FRBs that replicates, and it does a lot more than the others,” said Aggarwal. “Produced 75 bursts over a six-month period in 2020.”

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In the A-line graphs is the dynamic spectrum of the burst frequency with significant evidence of pulse amplification. In b are examples of bursts without significant evidence of pulse amplification. Credit: K. Aggarwal et al.

The team then used observations from the state-of-the-art Very Large Array (VLA) radio telescope in New Mexico, USA, to learn more about this FRB and was able to locate its source – a dwarf galaxy. billion light years from Earth. “That’s when we started to realize how important this FRB really is,” Aggarwal reported.

First, they discovered that a stable, albeit much weaker, radio signal was emitted by something from the same location that FRB190520 came from. “Since we were able to determine that the FRB originated 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 actual 3 billion light-years from Earth. galaxy.

Astronomers have only been able to determine the exact location – and therefore distance from Earth – of 19 other FRBs. For the rest of the known FRBs, astronomers must rely only on dispersal to estimate their distance from our planet.

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“For FRBs with known sites of origin, the estimated dispersal distances are very similar to the actual distances of their parent galaxies,” explained Aggarwal. “But this new FRB shows that estimates using diffusion can sometimes be incorrect and throw a lot of assumptions out of the window.”

and after

This new discovery raises some questions, such as whether persistent radio signals are common, what conditions they produce, and whether the same phenomenon that produces FRBs is responsible for emitting the persistent radio signal.

Furthermore, according to Agarwal, why the dispersion of FRB190520 was so much greater than it should be is also a big mystery. Was it due to something close to the FRB? Was it related to the persistent radio source? Did it have something to do with matter in the galaxy to which the FRB belongs? “All these questions have not been answered,” the researcher said, explaining that he and his team will focus on studying the phenomenon using several telescopes. different 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 study of this and other FRBs in the coming years. The larger the catalog of astronomers’ records, the greater their chance of discovering FRBs with exciting properties that could help unravel these fascinating astronomical phenomena.

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