We just discovered a fast radio burst from 3 billion light years away

The Research Brief is a short take about interesting academic work.

The big idea

A newly discovered fast radio burst has some unique properties that are simultaneously giving astronomers important clues into what may cause these mysterious astronomical phenomena while also 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 on June 8, 2022.

Fast radio bursts, or FRBs, are extremely bright pulses of radio waves that come from faraway galaxies. They release as much energy in a millisecond as the Sun does over many days. Researchers here at West Virginia University detected the first FRB back in 2007. In the past 15 years, astronomers have detected around 800 FRBs, with more being discovered every day.

When a telescope captures an FRB, one of the most important features researchers look at is something called dispersion. Dispersion is basically a measure of how stretched out an FRB is when it reaches Earth.

The plasma that lies 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 higher frequency light in the burst hits Earth before the lower frequencies, causing the dispersion. This allows researchers to use dispersion to estimate how far from Earth an FRB originated. The more stretched out an FRB is, the more plasma the signal must have passed through, the farther away the source must be.