Selections from 2025: A Repeating Fast Radio Burst in a Quiescent Galaxy

Editor’s Note: For the remainder of 2025, we’ll be looking at a few selections that we haven’t yet discussed on AAS Nova from among the most-downloaded articles published in AAS journals this year. The usual posting schedule will resume January 2nd.

A Repeating Fast Radio Burst Source in the Outskirts of a Quiescent Galaxy

Published January 2025

Main takeaway:

Using the Canadian Hydrogen Intensity Mapping Experiment (CHIME), Vishwangi Shah (McGill University) and collaborators discovered the repeating fast radio burst source FRB 20240209A. The team localized the source to roughly 130,000 light-years from the center of a quiescent elliptical galaxy about 1.8 billion light-years away. This suggests that the bursts originated from a globular cluster on the outskirts of the galaxy, pointing to a delayed formation pathway for the source.

Why it’s interesting:

Fast radio bursts are brief, intense flashes of radio waves from sources across the universe. Aside from one fast radio burst that has been associated with a magnetar within our own Milky Way, the source of these outbursts remains mysterious, and precise localization of these bursts is key to pinning down their origins; fast radio bursts that come from galaxies with active star formation may be linked to “prompt” formation channels like core-collapse supernovae or young magnetars, while bursts that arise in quiescent galaxies might be due to “delayed” formation pathways such as neutron stars that are born from merging white dwarfs.

How FRB 20240209A compares to other fast radio bursts, and what may have caused it:

FRB 20240209A is similar to other repeating fast radio bursts in terms of the shape of its individual bursts as well as its tendency to undergo periods of high and low bursting activity. Its location makes it quite unusual, though: it’s the only repeating fast radio burst known to come from a quiescent galaxy, and it’s the only burst — repeating or not — that has been found in an elliptical galaxy. If confirmed to originate from a globular cluster, FRB 20240209A would also be only the second known fast radio burst source to come from this type of environment. Shah’s team explored multiple possible origin stories for FRB 20240209A, including the possibility that the source was ejected from its host galaxy. The team favors an origin involving a magnetar formed through the collapse or merger of a compact object.

Citation

Vishwangi Shah et al 2025 ApJL 979 L21. doi:10.3847/2041-8213/ad9ddc