On March 4, 2024, the MeerTRAP project on South Africa's MeerKAT radio telescope caught a millisecond-long burst designated FRB 20240304B. The radio data hinted the source was extraordinarily distant, but confirming that required finding its host galaxy — and the world's largest ground-based telescopes, including a one-hour Keck exposure, could see nothing at the precise position. NASA's James Webb Space Telescope stepped in: NIRCam spotted a faint galaxy at the right spot, and NIRSpec measured a redshift of 2.148, placing the burst just 3 billion years after the Big Bang, during the era astronomers call 'cosmic noon' when star formation peaked. The signal traveled roughly 11 billion light-years, more than doubling the previous distance record for a localized FRB.

It lights up everything along the path,' said co-author J. Xavier Prochaska of UC Santa Cruz. The team identified two structures: a previously uncataloged galaxy cluster at redshift 0.3, roughly 3.5 billion light-years away, and the nearby Virgo Cluster about 54 million light-years from Earth. FRBs can thus trace the 'cosmic web' — the otherwise invisible matter between galaxies — letting a single millisecond flash map structures across most of cosmic history.

The team expects MeerKAT to detect and localize several FRBs per year at redshifts greater than 1.0 — bursts from more than halfway back to the start of the universe — and new radio facilities could accelerate that pace. Webb, whose NIRSpec spectra of hydrogen and oxygen lines made this distance measurement possible, will be essential for characterizing those distant host galaxies. 'Our results further show the amazing capability of Webb where we can push boundaries beyond what was previously possible,' said co-author Themiya Nanayakkara. Any complete explanation of FRBs must now account for bursts appearing in young, metal-poor galaxies like this one.

This is the kind of result the FRB community has been waiting for: a record more than doubling the known reach of localized bursts, from a host that upends assumptions. The Economic Times notes the discovery gives scientists an unprecedented look at conditions near the era of early galaxy formation, and informat.ro reports the burst crossed roughly 80% of cosmic history to reach Earth. The paper, published in Science, was led by Caleb with international co-authors — Hiru News highlighted that a Sri Lankan scientist was among the co-discoverers.