The researchers found that, while these millisecond-long flashes of light are invisible to human eyes, they glow with a veritable rainbow of radio wavelengths — and that could have big implications for what’s causing them.
“Once we analyzed the data, and compared the [different] radio colors, we were very surprised,” Inés Pastor-Marazuela, an astrophysicist at the University of Amsterdam and lead author of a new study on FRBs, said in a statement. The team determined the FRB was likely an isolated, slowly rotating magnetar, an extraordinarily dense, highly magnetic neutron star that crams the mass of a sun into a ball no wider than a city.
Light we cannot see
FRBs are some of the most energetic outbursts in the universe, packing more energy than the sun produces in three days into blips of light that last just a few milliseconds. Thousands of FRBs flash across the universe every day, but our human eyes see none of them; true to their name, FRBs only shine in radio wavelengths, far beyond the red edge of the visible spectrum.
However, the radio spectrum contains a miniature rainbow in its own right, with shorter radio wavelengths appearing blueish to radio telescopes, and longer wavelengths appearing reddish. In their new study, the researchers took a more detailed look at the radio “colors” of FRBs than ever before, by training two radio telescopes onto the same FRB source.
Using the Low-Frequency Array (LOFAR) and Westerbork Synthesis Radio Telescope (two radio telescopes from different facilities in the Netherlands), the researchers staked out a periodically-repeating FRB named 20180916B, which emits a salvo of bursts every 16 days or so.