New data from a Canadian-led team of astronomers, including researchers at the McGill Space Institute and McGill University’s Department of Physics, strongly suggests that magnetars – a type of supposed neutron star have an extremely strong magnetic field – could be the cause of some rapid radio bursts (FRBs).
Although much research has been done to explain the mysterious phenomenon, its source has so far remained elusive and is the subject of debate.
First detection of an intense radio burst of a galactic magnetar
On April 28, 2020, a team of about 50 students, post-docs and professors of the Fast Radio Burst Collaboration of the Canadian Hydrogen Intensity Mapping Experiment (CHIME) detected an unusually radio burst intense emanating from a nearby magnetar located in the Milky Way. In a study published today in Nature, they show that the intensity of the radio burst was three thousand times that of any magnetar measured so far, lending weight to the theory that magnetars are the source of at least a few FRBs .
“We calculated that such an intense burst from another galaxy would be indistinguishable from some rapid radio bursts, so this really lends weight to the theory suggesting that magnetars could be behind at least a few FRBs,” said Pragya Chawla , one of the co-authors of the study and a senior doctorate. student in McGill’s physics department.
Competing theories on the origins of FRBs
FRBs were first discovered over ten years ago. Originally thought to be singular events, astronomers have since discovered that some of these explosions of high-intensity radio emissions – more intense than the energy generated by the Sun for millions to billions of years – repeat themselves in fact.
One theory hypothesized that FRBs were extragalactic magnetars – young, extremely magnetic neutron stars that occasionally ignite to release enormous amounts of energy.
“So far, all of the FRBs that telescopes like CHIME have detected have been in other galaxies, which makes them quite difficult to study in detail,” said Ziggy Pleunis, a senior doctorate holder. a student in McGill’s physics department and one of the co-authors of the new study. “Additionally, the magnetar theory was not supported by observations of magnetars in our own galaxy, as they have been shown to be much less intense than the energy released by extragalactic FRBs so far.”
The origin of the magnetar for all FRBs remains to be confirmed
“However, given the large energetic and activity gaps between the brightest and most active FRB sources and what is observed for magnetars, perhaps younger, more energetic and active magnetars are needed to explain all FRB observations, ”added Dr. Paul Scholz of the Dunlap Institute for Astronomy and Astrophysics at the University of Toronto.
The smoking gun evidence of a magnetar origin for some FRBs would come from the simultaneous detection of an extragalactic radio burst and an X-ray burst. However, this will likely only be possible for nearby FRBs. Fortunately, CHIME / FRB is discovering them in good numbers.
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