Astronomers Detect Farthest Fast Radio Burst From Young Galaxy

Astronomers have identified FRB 20240304B, the most distant fast radio burst ever detected, after the signal was captured in March 2024 by MeerKAT in South Africa. The brief radio pulse traveled through most of the Universe's history from a young galaxy during cosmic noon.

The international research team used multiple observatories to locate the source of the burst, according to a study published in Science. The event lasted about one-thousandth of a second and came from a galaxy that existed when star formation was near its peak.

Researchers initially failed to find the host galaxy with ground-based telescopes before turning to the James Webb Space Telescope. According to the team, infrared observations and spectral analysis of oxygen and hydrogen lines revealed the galaxy's distance and age.

The source was a small dwarf galaxy rather than the large, mature galaxy many astronomers expected. UA.News reported that the system is about 1,000 times less massive than researchers anticipated, with 90 percent of its stellar mass forming during the past 30 million years.

"What makes fast radio bursts interesting is that we don't know what generates them," explained Manisha Caleb, lead author, radio astronomer and astrophysicist at the University of Sydney.

Caleb's team considered a magnetar, a neutron star with an extremely powerful magnetic field, as a possible origin for FRB 20240304B. The researchers said the young, metal-poor environment of the dwarf galaxy supports that possibility because magnetars can form within millions of years.

"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," said Manisha Caleb, lead author, radio astronomer and astrophysicist at the University of Sydney.

The study also examined how the radio signal changed while traveling across space. Its passage through ionized gas delayed lower-frequency waves more than higher-frequency waves, while turbulent gas likely stretched the signal by several milliseconds.

"We observationalists can only kill models, never prove them. So, when you have 100 to kill, it takes a fair bit of time," said J. Xavier Prochaska, astronomer and astrophysicist.

Prochaska said fast radio bursts remain difficult to explain because scientists have proposed many possible mechanisms. Researchers have confirmed host galaxies for about 100 FRBs, while the exact source of the signals remains unresolved.

"Fundamentally, it is because the energies involved are modest. They are extreme for radio wave emission, but nothing like the energy in a supernova or gamma-ray burst," said J. Xavier Prochaska, astronomer and astrophysicist at the University of California, Santa Cruz.

The burst also provided information about structures along its route. The signal revealed an unknown galaxy group about 3.5 billion light-years away and carried an ionic trace from the Virgo Cluster, located about 54 million light-years from Earth.

"Because we have scant understanding of what generates FRBs, we could only hope that they might exist at such early times," told J. Xavier Prochaska, astronomer and astrophysicist at the University of California, Santa Cruz.