Repeatingare among the more rare and recent mysteries in the cosmos, and the latest discovery of a repeater confounds astronomers' evolving understanding of the bright flashes of energy from deep space that last for just milliseconds.
Hundreds of FRBs have been spotted in the sky over the past 15 years, with the vast majority only detected once. But a small percentage of the bursts have been observed to repeat, allowing astronomers to trace over 20 FRBs back to their origins. One of the latest such discoveries is FRB 20200120E, which scientists followed back to a globular cluster of ancient stars in Bode's Galaxy and the famous constellation Ursa Major, also known as the Big Dipper.
This revelation came as a surprise to the researchers, because so far FRBs have been associated with magnetars, a type of highly magnetized neutron star that's not thought to exist among older star clusters.
"Thus, if FRB 20200120E represents an active magnetar, it must have formed through means that we have yet to witness," said CalTech astronomy professor Vikram Ravi, who was not involved with the research, in a commentary published in the latest issue of the journal Nature.
The details of FRB 20200120E are laid out in a study in the same journal from an international team of astronomers led by Franz Kirsten from Sweden's Chalmers University of Technology. The paper suggests that if the source of the repeating FRB is something other than a traditional magnetar, it could be something unique or unusual.
"We propose instead that FRB 20200120E originates from a highly magnetized neutron star formed either through the accretion-induced collapse of a white dwarf, or the merger of compact stars in a binary system," the paper's summary reads.
Put in simpler language, an old white dwarf star may have sucked up massive amounts of gas from a companion star or even swallowed a companion whole before collapsing into a magnetar.
Getting to the bottom of the mystery will require more observations. But the takeaway is that tracing an FRB back to such an unexpected source suggests there's still much more to learn about the phenomenon, and it may upend our understanding of other aspects of the universe along the way.