Webb traces record-distant fast radio burst to small galaxy

Astronomers have identified the host galaxy of FRB 20240304B, the most distant fast radio burst yet traced, using observations from the James Webb Space Telescope. The faint galaxy was already forming stars when the universe was about three billion years old, and its small size was unexpected. The burst’s physical cause remains unknown. The MeerKAT radio telescope array detected the millisecond-long burst on March 4, 2024. Its signal indicated that it came from far away, but ground-based telescopes could not see a galaxy at the precisely determined position. Researchers then used Webb to image the region and study the light from a faint galaxy there. Webb spectroscopy measured the galaxy’s redshift at 2.148. That measurement places it at an early stage of cosmic history, when the universe was roughly three billion years old. The finding more than doubles the previous distance record for a fast radio burst, according to the study. The researchers describe the host as a small, actively star-forming galaxy, rather than the larger galaxy they had expected. NASA’s account of the study says it was about 1,000 times less massive than researchers anticipated.