In 2022, Earth experienced an unexplained radio wave burst originating from a small group of galaxies situated approximately 8 billion light years away. This finding enhances our comprehension of the mechanisms behind the enigmatic fast radio bursts (FRBs).
Astronomers have identified over 1000 FRBs, which are peculiar bursts of radio-frequency electromagnetic radiation traversing the sky in mere milliseconds. Some of these events exhibit repetitive patterns, flashing multiple times. The leading hypothesis attributes FRBs to powerful rotating stars called magnetars—intensely magnetized, spinning remnants left after the explosion of massive stars as supernovae.
While approximately 50 FRBs have been traced back to sources within the Milky Way and other galaxies, 2022 witnessed the discovery of the most distant and potent FRB to date: the non-repeating FRB 20220610A, originating from when the universe was only five billion years old.
A team led by Alexa Gordon from Northwestern University in Illinois pursued further investigation. Using the Hubble Space Telescope in April 2023, the researchers determined that FRB 20220610A originated in a small dwarf galaxy within a compact group of seven galaxies, so diminutive that it could fit entirely inside our Milky Way. Gordon describes this as a “very rare system,” noting that, “At the distance of this FRB, only about 0.1 to 1 per cent of galaxies are in compact groups.”
Compact groups are believed to be active regions of star formation, supporting the magnetar theory for FRBs, as magnetars likely form early in a galaxy’s evolution during the explosion of hot and massive stars. In compact groups, the galaxies interact frequently, triggering star formation patterns consistent with observations of FRBs generated by sources that are younger and closer to Earth.
The findings were shared on the arXiv preprint server late last year and were presented at a meeting of the American Astronomical Society in New Orleans, Louisiana. This discovery broadens our understanding of the diverse environments in which FRBs can exist, as they have been observed not only in star-forming spiral galaxies but also in galaxy clusters, dwarf galaxies, and globular clusters.
