Millisecond-long radio bursts from billions of light-years away, with some sources repeating in patterns. The mechanism producing such intense energy remains unknown.
A Torrent of Energy
Across the unimaginable distances of intergalactic space, something is producing fleeting, powerful blasts of radio waves. These Fast Radio Bursts (FRBs) last for only a few milliseconds, yet in that sliver of time, they can release as much energy as the Sun does in three days. The first FRB, known as the Lorimer Burst, was identified in 2007 from archival data recorded years earlier. For years, every detected FRB was a singular event, a cosmic flash that was never seen again. This suggested they might be caused by cataclysmic events, like the collision of two dense stellar cores.
That picture changed with the discovery of FRB 121102. First detected in 2012 by the Arecibo Observatory in Puerto Rico, it was observed to flash again, making it the first known repeater. This discovery proved that at least some FRB sources can survive the process that creates the bursts. FRB 121102 is located in a dwarf galaxy about three billion light-years from Earth. Since then, hundreds of FRBs have been cataloged, with a small but growing fraction identified as repeaters. These repeating sources give astronomers a chance to study the phenomenon in detail, pointing their telescopes at a known location in the sky and waiting for the next eruption.
The Cosmic Clockwork
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope has helped expand the catalog of known FRBs, finding 535 new bursts in its first year of operation alone. Among its most significant discoveries is FRB 180916.J0158+65, the first repeater found to have a predictable, periodic cycle. This object, located in a spiral galaxy 500 million light-years away, emits radio bursts within a window of about four days, then goes silent for twelve, repeating this 16.35-day cycle with consistency.
The leading explanation for the engines behind FRBs, particularly the repeaters, are magnetars. These are a type of neutron star—the incredibly dense collapsed core of a massive star—that have magnetic fields of great power. A "starquake" on a magnetar's crust or a violent interaction in its surrounding magnetosphere could unleash the energy required to generate an FRB. The regular cycle of FRB 180916.J0158+65 might be explained by the magnetar's orbit around another object, like a star or a black hole, where the bursts are only visible from Earth at a certain point in its orbit. Another possibility is a wobble in the magnetar's rotational axis, known as precession. While the exact mechanism is still under investigation, the clockwork pattern of some repeaters provides a clue in understanding these bursts.
💡Fun Facts
The energy released in a single millisecond FRB can be greater than the amount of energy the Sun produces in an entire year.
The first repeating FRB, named FRB 121102, was discovered using the 305-meter Arecibo radio telescope in Puerto Rico.
One hyperactive source, FRB 20220912A, was observed emitting 128 distinct bursts in less than two hours.
The plasma that FRB signals travel through slightly slows down lower-frequency radio waves. This effect, called dispersion measure, allows astronomers to estimate the immense distances to the bursts' home galaxies.