Evrim Yazgin
Cosmos science journalist
A new discovery adds to the mystery of the source of fast radio bursts.
Fast radio bursts (FRBs) are extremely energetic pulses of radio-frequency light which travels across the universe that last just a few seconds or even milliseconds.
More than 1,000 FRBs have been reported since the first was discovered in 2007.
FRB 20240209A, however, is the first to be discovered on the outskirts of an ancient, dead elliptical galaxy. FRBs to date have been associated with much younger, star-forming galaxies with more activity. The FRB is reported in two papers published in the Astrophysical Journal Letters.
It only raises more questions about the origins of these enigmatic objects.
“The prevailing theory is that FRBs come from magnetars formed through core-collapse supernovae. That doesn’t appear to be the case here,” says Tarraneh Eftekhari from Northwestern University in the USA. Eftekhari led one of the studies and co-authored the other.
“While young, massive stars end their lives as core-collapse supernovae, we don’t see any evidence of young stars in this galaxy,” she adds. “Thanks to this new discovery, a picture is emerging that shows not all FRBs come from young stars. Maybe there is a subpopulation of FRBs that are associated with older systems.”
“This new FRB shows us that just when you think you understand an astrophysical phenomenon, the universe turns around and surprises us,” says Northwestern’s Wen-fai Fong, a senior author on both studies. “This ‘dialogue’ with the universe is what makes our field of time-domain astronomy so incredibly thrilling.”
FRB 20240209A was first detected in February 2024 using the Canadian Hydrogen Intensity Mapping Experiment (CHIME). Between February and July 2024, the source pulsed 21 more times.
The FRB is just 2 billion light-years from Earth in an elliptical galaxy which is 11.3 billion years old.
As well as being in a strangely old galaxy, FRB 20240209A is also the FRB furthest from the centre of its host galaxy. It sits on the outskirts of the galaxy, about 130,000 light-years from the centre where few stars exist.
“This is both surprising and exciting, as FRBs are expected to originate inside galaxies, often in star-forming regions,” says Vishwangi Shah, a graduate student at McGill University, USA. “The location of this FRB so far outside its host galaxy raises questions as to how such energetic events can occur in regions where no new stars are forming.”
