Astronomers have been puzzling over the mysterious origins of fast radio bursts (FRBs) since they were first detected in 2007. Now scientists at the University of Tokyo have come up with new evidence that at least some FRBs may be caused by so-called "starquakes" on the surfaces of neutron stars, according to a new paper published in the Monthly Notices of the Royal Astronomical Society.

As Ars Science Editor John Timmer reported previously, FRBs involve a sudden blast of radio-frequency radiation that lasts just a few microseconds. Astronomers have cataloged hundreds of them; some come from sources that repeatedly emit FRBs, while others seem to burst once and go silent. You can produce this sort of sudden surge of energy by destroying something. But the existence of repeating sources suggests that at least some of them are produced by an object that survives the event. That has led to a focus on compact objects, like neutron stars and black holes—especially a class of neutron stars called magnetars—as likely sources.

Magnetars are an extreme form of a neutron star, a type of body that is already notable for being extreme. They are the collapsed core of a massive star, so dense that atoms get squeezed out of existence, leaving a swirling mass of neutrons and protons. That mass is roughly equal to the Sun's but compressed into a sphere with a radius of about 10 kilometers. Neutron stars are best known for powering pulsars, rapidly repeating bursts of radiation driven by the fact that these massive objects can complete a rotation in a handful of milliseconds.

Magnetars are a different type of extreme. They tend not to rotate as quickly but have intense magnetic fields about a trillion times stronger than the Earth's magnetic field. While the period of high magnetic fields only lasts a few thousand years before the fields dissipate, there are enough neutron stars to keep a regular supply of magnetars around. Their magnetic fields can power highly energetic events, either by accelerating particles or through magnetic disturbances driven by material shifting within the neutron star.

In 2020, the Canadian Hydrogen Intensity Mapping Experiment (CHIME) spotted what looked like an FRB coming from a so-called "soft gamma-ray repeater," dubbed SGR 1935+2154. The results were consistent with an association between the FRB and the gamma ray output. The Survey for Transient Astronomical Radio Emission 2 (STARE2) was able to pick up the same event. There was just enough uncertainty to keep astrophysicists arguing, although the fact that a magnetar could produce something that looks so much like an FRB was promising.

There have also been a number of FRBs that don't seem to repeat at all, suggesting that the conditions that produced them may destroy their source. That is consistent with a blitzar—a bizarre astronomical event caused by the sudden collapse of an overly massive neutron star. The event is driven by an earlier merger of two neutron stars; this creates an unstable intermediate neutron star, which is kept from collapsing immediately by its rapid spin.