Evrim Yazgin
Cosmos science journalist
Astronomers believe they have narrowed down the search for the origin of fast radio bursts (FRBs) to massive star-forming galaxies.
Since the first FRB was detected in 2007, hundreds have been spotted. The observations all involve extremely energetic pulses of radio-frequency light which can travel across the universe.
Evidence is mounting that the source of FRBs is magnetised neutron stars called magnetars.
New research published in Nature suggests that FRBs are more likely to occur in large, active galaxies than low-mass ones. The finding also sheds light on how magnetars themselves might form.
“The immense power output of magnetars makes them some of the most fascinating and extreme objects in the universe,” says lead author Kritti Sharma, a graduate student at Caltech. “Very little is known about what causes the formation of magnetars upon the death of massive stars. Our work helps to answer this question.”
The research used data from the Owens Valley Radio Observatory about 350km north of Los Angeles.
The radio array detected 70 FRBs and determined which galaxies hosted the bright events as part of Caltech’s Deep Synoptic Array-110 (DSA-110) project.
“DSA-110 has more than doubled the number of FRBs with known host galaxies,” says co-author and Caltech assistant professor Vikram Ravi. “This is what we built the array to do.”
Large galaxies tend to be rich in elements heavier than hydrogen or helium. The fact that FRBs are more common in these galaxies suggests that magnetars may also have a high abundance of heavy elements, referred to broadly as metals by astronomers.
“Over time, as galaxies grow, successive generations of stars enrich galaxies with metals as they evolve and die,” explains Ravi.
It’s possible that the formation of magnetars is also linked to binary star systems which host 84% of all massive stars.
“A star with more metal content puffs up, drives mass transfer, culminating in a merger, thus forming an even more massive star with a total magnetic field greater than what the individual star would have had,” Sharma says.
The researchers hope to find more FRBs and their host galaxies using DSA-110 and, in the future, DSA-2000 – an even bigger array planned to be build in the desert in Nevada due to be completed in 2028.
