Home Radio waves How a new radio signal from deep space baffled the scientist who found it

How a new radio signal from deep space baffled the scientist who found it


A new The fast radio burst discovered has unique properties that simultaneously give astronomers important clues about what may be causing these mysterious astronomical phenomena while calling into question one of the few things scientists thought they knew about these powerful flares, as my colleagues and I describe in a new study in Nature June 8, 2022.

Fast Radio Bursts, or FRBs, are extremely bright pulses of radio waves from distant galaxies. They release as much energy in a millisecond as the sun is several days. Researchers here at West Virginia University detected the first FRB in 2007. Over the past 15 years, astronomers have detected about 800 FRBs, with more to discover every day.

When a telescope captures an FRB, one of the most important characteristics researchers look at is something called scattering. Dispersion is essentially a measure of the extent of an FRB when it reaches Earth.

Plasma between stars and galaxies slows down all light, including radio waves, but low frequencies feel this effect more strongly and slow down more than high frequencies. FRBs contain a range of frequencies, so the high frequency light from the burst hits the Earth before the low frequencies, causing scattering. This allows researchers to use dispersion to estimate how far from Earth an FRB is born. The wider an FRB is, the more plasma the signal must have passed through and the further away the source must be.

The top of this diagram shows six peaks in radio wave brightness which are six bursts of FRB190520. The bottom half shows the frequency range for each individual burst.Niu, CH, Aggarwal, K., Li, D. et al.

Why is it important – The new FRB that my colleagues and I discovered is named FRB190520. We found it using the Five Hundred Meter Aperture Spherical Telescope in China. One interesting thing immediately apparent about FRB190520 was that it is one of only 24 repeating FRBs and repeats much more frequently than the others – producing 75 bursts over a six-month period in 2020.

Our team then used the Very large painting, a radio telescope in New Mexico, to further study this FRB and successfully pinpoint the location of its source – a dwarf galaxy about 3 billion light-years from Earth. That’s when we started to realize how unique and important this FRB really is.

First, we found that there is a persistent, although much weaker, radio signal emitted by something from the same place as FRB190520. Among the more than 800 FRBs discovered to dateonly one other has a similar persistent radio signal.

Second, since we were able to determine that the FRB originated from a dwarf galaxy, we were able to determine exactly how far this galaxy is from Earth. But this result did not make sense. To our surprise, the distance estimate we made using FRB scattering was 30 billion light-years from Earth, a distance ten times greater than the galaxy’s actual 3 billion light-years.

Astronomers have only been able to determine the exact location – and therefore the distance from Earth – from 19 other FRB sources. For the rest of the approximately 800 known FRBs, astronomers must rely solely on scatter to estimate their distance from Earth. For the other 19 FRBs with known locations, the distances estimated from the scatter are very similar to the actual distances to their source galaxies. But this new FRB shows that estimates using dispersion can sometimes be incorrect and reject many assumptions.

FRB190520 originated from a small dwarf galaxy 3 billion light years away, marked by the reticle in the larger inset with the exact location of the FRB source in the circle in the smaller image.Niu, CH, Aggarwal, K., Li, D. et al.

What is not yet known – Astronomers in this new field I still do not know what exactly produces FRBstherefore each new discovery or information is important.

Our new discovery raises specific questions, including whether persistent radio signals are common, what conditions produce them, and whether the same phenomenon that produces FRBs is responsible for emitting the persistent radio signal.

And a huge mystery is why the dispersion of FRB190520 was so much larger than it should be. Was it due to something near the FRB? Was it related to the persistent radio source? Does it have to do with matter in the galaxy this FRB is from? All these questions are unanswered.

And after – My colleagues will focus on studying FRB190520 using a multitude of different telescopes around the world. By studying the FRB, its galaxy, and the space environment surrounding its source, we hope to find answers to many of the mysteries it has revealed.

Other answers will also come from other FRB discoveries in the years to come. The more FRBs astronomers catalog, the greater their chances of discovering FRBs with interesting properties that can help complete the puzzle of these fascinating astronomical phenomena.

This article was originally published on The conversation by Kshitij Aggarwal at West Virginia University. Read it original article here.