Astronomers have detected the most distant fast radio burst (FRB) ever recorded, a millisecond-long explosion of radio waves that traveled for more than 10 billion years. The signal, designated FRB 20240304B, originated when the universe was only 3 billion years old, more than doubling the previous distance record for these enigmatic cosmic events.
Detecting FRB 20240304B with MeerKAT and Webb
Scientists used the MeerTRAP system, designed to catch fast-changing transient radio signals from space in real time, to pin down the burst’s precise location. While the large dispersion of the radio signal suggested it had traveled an immense distance, the researchers knew the burst was far away because of the large dispersion of the radio signal, which acts as a crude proxy for distance.
By utilizing the Near-Infrared Camera (NIRCam), astronomers successfully identified a tiny, faint galaxy at the exact coordinates of the radio signal. Follow-up spectroscopy using the telescope’s Near-Infrared Spectrograph confirmed the galaxy exists at a cosmological redshift of 2.148, placing the event roughly 11 billion light-years away, or just 3 billion years after the big bang.
An Unexpected Dwarf Galaxy Host
The findings, published in the journal Science, challenged existing theories about the environments that produce fast radio bursts. While most previously studied FRBs originated in massive star-forming galaxies, the host of FRB 20240304B was 1,000 times less massive than expected. Manisha Caleb, an astrophysicist at the University of Sydney and lead author of the study, described the time frame as “insane,” noting that when the light left the source, the Sun and the solar system did not yet exist.
“We thought it would be a big, nicely formed galaxy with lots of stars, and instead it was a little dwarf galaxy, although it was actively forming stars.”
Manisha Caleb, University of Sydney
Ben Stappers of the University of Manchester, a co-author on the paper, added that the host definitely was not what the team was expecting. Nanayakkara stated that any mechanism explaining these bursts must account for the fact that they can arise in very young galaxies with very little metal. Because the galaxy is young, it supports the idea that at least some FRBs are generated by magnetars, which are more likely to appear in spry galaxies where intense star formation is occurring.
Probing the Cosmic Web
The team found the imprint of two cosmic structures on the signal: one previously unknown galaxy cluster at a redshift of 0.3, and the nearby Virgo Cluster, located about 54 million light-years from Earth.
Matthew Bailes of Swinburne University, who was involved in the first discovery of FRBs in 2007, described the new study as confirmation of how powerful bursts are as a tool for exploring the universe.
He noted they provide a fundamental way of counting atoms in the universe. Xavier Prochaska, an astronomer and astrophysicist at the University of California, Santa Cruz, observed that theorists have devised nearly 100 models to generate these bursts, but observationalists can only kill models, never prove them.
Future Prospects for Deep-Universe Detections
The successful collaboration between radio arrays and the JWST has opened a new frontier. While researchers are still uncertain if FRB 20240304B will repeat, the ability to pinpoint its host galaxy has validated the use of infrared space telescopes to complement radio data.
Joeri van Leeuwen of the ASTRON Netherlands Institute for Radio Astronomy, who was not involved in the research, remarked that every large collection begins with just one specimen. The team plans to continue hunting for FRBs with the JWST, relying on ground-based radio telescopes to trigger future observations. As Nanayakkara explained, it is exciting because they really have no idea what they will find when they combine the power of these two types of telescopes.