Fast radio bursts are brief bursts of radio waves originating from extremely compact objects such as neutron stars and black holes. These fleeting events last for just a thousandth of a second but can carry a tremendous amount of energy, outshining entire galaxies momentarily. Since the first fast radio burst was discovered in 2007, astronomers have detected thousands of these bursts ranging from within our own galaxy to as far as 8 billion light-years away. The exact mechanism behind these bursts remains a mystery.
A team of astronomers at MIT has identified the origins of at least one fast radio burst using a new technique that could potentially be applied to other FRBs. The study focused on FRB 20221022A, a burst detected from a galaxy about 200 million light-years away. By analyzing the scintillation of the burst, the team was able to determine that the radio signal must have originated very close to its source, challenging previous models that predicted a much farther source of the bursts.
The team estimated that FRB 20221022A was emitted from a region just 10,000 kilometers away from a rotating neutron star, a distance closer than that between New York and Singapore. The burst is believed to have emerged from the neutron star’s magnetosphere, a highly magnetic region surrounding the compact star. This finding provides conclusive evidence that fast radio bursts can originate from the magnetosphere, a challenging environment where atoms cannot exist due to extreme magnetic fields.
Using the Canadian Hydrogen Intensity Mapping Experiment (CHIME), astronomers have detected thousands of fast radio bursts since 2020. These bursts are believed to arise from compact objects, but the exact physics driving them remain unclear. By analyzing scintillation, where light bends through a medium, the researchers were able to estimate the region from where FRBs originate. Small regions indicate close sources, while larger regions suggest farther sources, supporting different theories about the origins of FRBs.
FRB 20221022A, a typical fast radio burst, exhibited unique properties such as high polarization, hinting at its possible origin close to a rotating neutron star. The team observed variations in brightness indicating scintillation and confirmed the existence of gas bending and filtering radio waves between the telescope and the FRB. By zooming in on the FRB site, the researchers estimated a width of just 10,000 kilometers, suggesting the burst originated within hundreds of thousands of kilometers from the source, ruling out the possibility of a far-out shockwave.
These findings, combined with studies from collaborators at McGill University, provide evidence that fast radio bursts can emerge from chaotic and highly magnetic environments very close to neutron stars. With the ability to detect several FRBs a day, the scintillation technique developed in this study will be essential in understanding the complex physics behind these mysterious cosmic phenomena. The research was supported by various institutions and organizations focused on advancing our knowledge of the universe.