As my colleagues and I describe in a new study in Nature on June 8, 2022, a newly discovered fast radio burst has a unique set of properties that simultaneously give astronomers important clues into what may cause these mysterious astronomical events, as well as questioning one of the few things scientists thought they knew about these highly energetic flares.

FRBs, or fast radio bursts, are extremely bright pulses of radio waves that originate from faraway galaxies. In a millisecond, they release as much energy as the Sun does over many days. In 2007, researchers here at West Virginia University detected the first FRB. Astronomers have detected about 800 FRBs in the past 15 years, with more being discovered every day.

Dispersion is one of the most important features that researchers look for when observing an FRB. An FRB's dispersion is basically how stretched out it is when it reaches Earth.

The plasma that lies between stars and galaxies slows all light, including radio waves, but lower frequencies feel this effect more strongly and slowed down more than higher frequencies. An FRB contains a range of frequencies, so the higher frequency light hits Earth before the lower frequencies, causing dispersion. Researchers can use dispersion to estimate the distance of an FRB from Earth. The more stretched out an FRB is, the more plasma the signal has passed through, and the farther away the source must be.

My colleagues and I discovered a new FRB named FRB190520. In China, we found it using the Five-hundred-meter Aperture Spherical Telescope. One thing immediately apparent about FRB190520 is that it is one of only 24 repeating FRBs and that it repeats much more often than others - producing 75 bursts over six months in 2020.

Our team then used the Very Large Array, a radio telescope in New Mexico, to study this FRB further and locate its source - a dwarf galaxy about 3 billion light-years from Earth. After that, we began to realize how unique and important this FRB is.

First, we found a persistent radio signal, though much fainter, coming from the same location as FRB190520. Among the more than 800 FRBs discovered to date, only one has a similar persistent radio signal.

Second, since we were able to pinpoint that the FRB originated from a dwarf galaxy, we were able to determine exactly how far that galaxy is from Earth. However, the result did not make sense. To our surprise, the distance estimate we made using the dispersion of the FRB was 30 billion light-years from Earth, a distance 10 times greater than the actual 3 billion light-years.

Astronomers have pinpointed the exact location - and consequently, distance from Earth - of 19 other FRB sources. Astronomers estimate the distance of the rest of the roughly 800 known FRBs based only on dispersion.

The distances estimated from the dispersion are very close to the real distances to the source galaxies of the other 19 FRBs. But this new FRB shows that estimates using dispersion are sometimes incorrect, throwing many assumptions out the window.