Friday, June 10, 2022, 11:43 a.m .: Researchers used a radio telescope in New Mexico to study a particularly interesting fast radio.
The Research Brief is a brief presentation on interesting academic papers.
THE GREAT IDEA
A recently discovered rapid radio explosion has some unique properties that at the same time give astronomers important clues as to what can cause these mysterious astronomical phenomena while questioning one of the few things scientists thought they knew about these powerful flares, such as my colleagues and I describe. in a new study in Nature on June 8, 2022.
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Rapid radio bursts, or FRBs, are extremely bright pulses of radio waves coming from distant galaxies. They release as much energy in a millisecond as the Sun does for many days. Researchers at the University of West Virginia detected the first FRB in 2007. In the last 15 years, astronomers have detected about 800 FRBs, and more are being discovered every day.
When a telescope captures an FRB, one of the most important features that researchers observe is something called scattering. Dispersion is basically a measure of how a FRB is stretched when it reaches Earth.
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. FRBs contain a range of frequencies, so the light with the highest frequency of the explosion reaches the Earth before the lowest frequencies, causing it to scatter. This allows researchers to use scatter to estimate how far from the Earth an FRB originated. The more widespread an FRB is, the more plasma the signal must have passed, the farther away the source must be.
The top of this diagram shows six peaks of radio wave brightness which are six bursts of FRB190520. The bottom half shows the frequency range for each individual burst. Credit: Niu, CH., Aggarwal, K., Li, D. et al. (CC BY 4.0)
WHY IT MATTERS
The new FRB that my classmates and I discovered is called FRB190520. We found it using the five-hundred-meter aperture spherical telescope in China. One immediately apparent interesting thing about FRB190520 was that it is one of only 24 FRBs to be repeated and repeated much more frequently than others, producing 75 bursts in a six month period by 2020.
Our team then used the Very Large Array, a New Mexico radio telescope, to further study this FRB and successfully identified the location of its source: a dwarf galaxy about 3 billion light-years from Earth. That’s when we started to realize how truly unique and important this FRB is.
First of all, we found that there is a persistent radio signal, although much weaker, emitted by something from the same place where FRB190520 comes from. Of the more than 800 FRBs discovered so far, only one has a similar persistent radio signal.
Second, since we were able to determine that the FRB came from a dwarf galaxy, we were able to determine exactly how far away this galaxy is from Earth. But that result made no sense. To our surprise, the estimated distance we did with the scattering of the FRB was 30 billion light-years from Earth, a distance 10 times greater than the actual 3 billion light-years in the galaxy. .
Astronomers have only been able to locate the exact location, and therefore the distance from Earth, of 19 other FRB sources. For the remaining approximately 800 known FRBs, astronomers should rely solely on scattering to estimate their distance from Earth. For the other 19 FRBs with known locations, the estimated distances from the scatter are very similar to the actual distances to their source galaxies. But this new FRB shows that the estimates used by the scatter can sometimes be incorrect and throws a lot of assumptions out the window.
FRB190520 comes from a small dwarf galaxy 3 billion light-years away, marked by the cross of the largest insertion with the exact location of the FRB source in the circle of the smallest image. Credit: [Niu, CH., Aggarwal, K., Li, D. et al.](CC BY 4.0)
WHAT IS NOT YET KNOWN
Astronomers in this new field do not yet know exactly what FRBs produce, so every new discovery or information is important.
Our new discovery raises specific questions, such as whether persistent radio signals are common, what conditions produce them, and whether the same phenomenon that produces FRB is responsible for emitting the persistent radio signal.
And one big mystery is why the dispersion of FRB190520 was much bigger than it should be. Was it because of something close to the FRB? Was it related to the persistent radio source? Does it have to do with the matter in the galaxy where this FRB comes from? All of these questions are unanswered.
THAT FOLLOWS
My colleagues will focus on studying FRB190520 with a lot of different telescopes around the world. As we study the FRB, its galaxy, and the space environment surrounding its source, we look forward to finding answers to many of the mysteries it revealed.
More answers from other FRB discoveries will also come in the coming years. The more catalog of FRB astronomers, the more chances you have to discover FRB with interesting properties that can help complete the puzzle of these fascinating astronomical phenomena.
Kshitij Aggarwal, affiliated researcher in astronomy and astrophysics, University of West Virginia
This article is republished from The Conversation under a Creative Commons license. Read the original article.
(Thumbnail courtesy of Diana Robinson / Flickr, provided by the original author)