Astronomers find new clues about mysterious bursts in deep space

Astronomers may be a step closer to unlocking the mysteries of fast radio bursts (FRBs) - powerful cosmic events that last for a fraction of a second and can release about as much energy as the Sun does in a year.

FRBs are so brief that it is often hard to pinpoint their source. Using two NASA X-ray telescopes, researchers recently observed one such event minutes before and after it occurred.

In 2020, a fast radio burst erupted in Earth's home galaxy and its source was traced to a magnetar called SGR 1935+2154 (SGR 1935 for short). Magnetars are the supermagnetized remains of an exploded star many times more massive than our Sun.

In October 2022, the same magnetar produced another FRB, which was studied in detail by NASA's NICER (Neutron Star Interior Composition Explorer) on the International Space Station and NuSTAR (Nuclear Spectroscopic Telescope Array) in low Earth orbit. The two X-ray telescopes observed the magnetar for hours to understand what happened before and after the event took place.

The researchers found that the burst occurred between two "glitches" - when the magnetar suddenly started spinning faster. They were surprised to see that in between glitches, the magnetar slowed down to less than its pre-glitch speed in just nine hours, or about 100 times faster than previously recorded for such a stellar remnant.

Scientists consider a lot of variables when trying to understand how exactly FRBs are produced by magnetars. For instance, magnetars have high density, which also means they have a strong gravitational pull. The strong gravity means the surface of a magnetar is a volatile place, regularly releasing bursts of X-rays and higher-energy light.

What else might have happened with SGR 1935+2154 to produce a fast radio burst?

The study authors believe that the exterior of a magnetar is solid, and the high density crushes the interior into a state called a superfluid. Occasionally, the two can get out of sync and when this happens, the fluid can deliver energy to the crust. The researchers think that this is likely what caused both glitches that bookended the FRB.

A crack in the magnetar's surface due to the initial glitch might have released material into space. Losing mass causes spinning objects to slow down and this, as the researchers believe, could explain the rapid deceleration observed.

However, with only one such event observed in real-time, researchers are unsure which of these factors could contribute to these powerful cosmic phenomena, underscoring the need for further observation and study.