The second fast radio burst (FRB) ever seen was recently detected from far beyond our galaxy, by researchers at the Canadian Hydrogen Intensity Mapping Experiment (CHIME) in Canada. Astronomers recorded the event on January 9.
Fast radio bursts are powerful blasts of energy occurring millions of light years outside the Milky Way galaxy, lasting just a few thousandths of a second. They are typically broadband (meaning they cover a wide range of frequencies), and they release, in just a small fraction of a second, as much energy as the Sun produces in decades. Six such bursts were detected by CHIME researchers, emanating from an object dubbed FRB 180814.J0422+73.
“Until now, there was only one known repeating FRB. Knowing that there is another suggests that there could be more out there. And with more repeaters and more sources available for study, we may be able to understand these cosmic puzzles—where they’re from and what causes them,” said Ingrid Stairs, researcher on the CHIME team and an astrophysicist at the University of British Columbia.
The first FRB was discovered in 2007, by astronomers Duncan Lorimer and David Narkevic as they were examining archival data from pulsars. Today, FRB’s remain one of the least-understood phenomenon in all of astronomy. Of the 60-odd events recorded so far, this is only the second one which has repeated, providing astronomers with a chance to determine its exact origin. The first repeating FRB was seen by astronomers in 2015, utilizing the Arecibo radio telescope in Puerto Rico.
The FRB’s seen by CHIME showed signs of scattering – suggesting they were formed in an area with unusual characteristics, such as near a black hole, or at the centers of a galaxy (which, by and large, contain super-massive black holes).
The CHIME detector is a new instrument, but it has already found 13 FRB’s in just three weeks of testing during the summer of 2018, despite not yet being at full capacity. Once CHIME is running at full capacity, astronomers predict they may detect several dozen FRB’s every day.
“This second repeater, found among the first few CHIME/FRB discoveries, suggests that there exists—and that CHIME/FRB and other wide-field, sensitive radio telescopes will find—a substantial population of repeating FRBs,” researchers at the Canadian Hydrogen Intensity Mapping Experiment (CHIME) reported.
Despite the fact that most of the FRB’s previously recorded had frequencies around 1,400 MHz, the CHIME detector was designed to detect FRB’s emanating radiation in the range of 400 to 800 MHz. This led some astronomers to question whether CHIME would be able to see FRB’s as they occurred, but those concerns have now been shown to be unfounded. Some of the FRB’s detected by CHIME at the lower range of frequencies were so bright, astrophysicists are predicting many more could be found at even lower wavelengths.
Finding these FRB’s at such low frequencies could assist astronomers in piecing together the processes which produce the phenomenon. Possibilities include the collisions of ultra-dense neutron stars or highly-charged magnetars – a special class of neutron stars with powerful magnetic fields. Several theories of the creation of FRB’s have now been ruled out, as radio bursts produced by these methods would be exclusively at higher frequencies than those seen by CHIME.
The discovery of another repeating FRB has lead some people in the general public to believe these signals could be the sign of intelligent extraterrestrial life, but astronomers are still trying to piece together how FRB’s could be produced by natural events. Although little green men could be behind it all, big black holes or neutron stars are more likely the culprits.