Mysterious Fast Radio Bursts May Have a Surprising Source: A Binary Stellar System
Fast radio bursts are some of the strangest signals we pick up from space. They last just a few thousandths of a second, but they can outshine whole galaxies in radio light while they’re happening. For years, one big question has been hanging around: what kind of object can make something that loud and fast – and sometimes do it again and again?
But here's where it gets controversial: a long set of telescope observations has added a major piece to the puzzle. The key idea is simple. Some of these repeating fast radio burst sources are not alone in space – they have company.
A signal that points to two stars
The new work centers on a repeating source called FRB 220529A, located about 2.5 billion light-years away. Over nearly 20 months, astronomers watched it closely enough to catch a rare change in the radio signal. The kind of change that was detected could only happen if the burst source sits in a messy, active neighborhood.
That neighborhood looks a lot like a binary stellar system, where two stars orbit each other. Instead of an isolated star sending bursts into empty space, the repeating source appears to share its space with a nearby partner star that can stir up the environment around it.
The observations were led by an international team using the Five-hundred-meter Aperture Spherical Telescope (FAST) in Guizhou. FAST, also called the “China Sky Eye,” is huge – with a dish about 1,640 feet across. The team also used Australia’s Parkes radio telescope to support the result.
Radio wave with strange activity
Fast radio bursts are known for having radio waves that are almost perfectly lined up in a single direction, a property called linear polarisation. As those waves move through hot, charged gas threaded with magnetic fields, the angle of that polarisation can rotate. Scientists measure that effect using something called rotation measure, or RM.
In late 2023, the team saw RM swing wildly for FRB 220529A, then settle back down. The team calls this short, sharp event an “RM flare.” It acts like a fingerprint of the material the radio waves passed through right before reaching Earth.
Linking magnetars to fast radio bursts
The new result lines up with an idea many astronomers already take seriously: magnetars may be behind at least some fast radio bursts. A magnetar is a type of neutron star, the ultra-dense remnant left after a massive star explodes, with a magnetic field so strong it can reshape the space around it. When a magnetar sits near another star, that partner can dump plasma into the area, changing what the burst signal looks like when it leaves.
Professor Zhang said, "This finding provides a definitive clue to the origin of at least some repeating FRBs. The evidence strongly supports a binary system containing a magnetar – a neutron star with an extremely strong magnetic field, and a star like our Sun."
The team credits the result to long, careful observing time and persistence across multiple facilities. According to Professor Xuefeng Wu of Purple Mountain Observatory, the discovery was made possible by the persevering observations using the world’s best telescopes and the tireless work of a dedicated research team.
The full study was published in the journal Science. Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.
