Researchers suggest that this brief cosmic explosion likely originated within the chaotic magnetic environment surrounding a distant neutron star.

Scientists Uncover Origins of Fast Radio Bursts

Fast radio bursts (FRBs) are intense, short-lived blasts of radio waves emitted by highly compact objects like neutron stars or, potentially, black holes. These bursts last only a millisecond but can release an extraordinary amount of energy, briefly outshining entire galaxies.

Since their discovery in 2007, thousands of FRBs have been detected, with their origins spanning from our galaxy to locations as far as 8 billion light-years away. However, the exact mechanism behind these cosmic phenomena remains a subject of intense debate.

A team of MIT astronomers has now pinpointed the origin of a specific FRB, known as FRB 20221022A, using an innovative approach that could help trace the origins of other FRBs. Their findings, published in Nature, focus on a burst detected in a galaxy roughly 200 million light-years away.

The researchers identified the precise location of the signal by studying its "scintillation," a phenomenon similar to the twinkling of stars. By analyzing variations in the burst's brightness, they determined that the signal originated very close to its source, rather than farther away as previously hypothesized.

Their analysis reveals that FRB 20221022A likely erupted from a region within 10,000 kilometers of a neutron star—a distance shorter than the span between New York and Singapore. This proximity strongly suggests the burst originated in the star’s magnetosphere, an intensely magnetic area surrounding the compact object.

The study provides the first solid evidence that FRBs can emerge from the magnetospheres of neutron stars. "The magnetic fields around these stars are at the extreme limits of what the universe can create," explains lead author Kenzie Nimmo, a postdoctoral researcher at MIT’s Kavli Institute for Astrophysics and Space Research.

These extreme conditions present unique challenges. "In the vicinity of magnetars—highly magnetic neutron stars—even atoms cannot survive, as they are torn apart by the intense fields," says Kiyoshi Masui, associate professor of physics at MIT. He adds, "What’s fascinating is how the energy stored in these magnetic fields reconfigures and twists, releasing radio waves that travel across vast cosmic distances to reach us."

The MIT team, which includes Adam Lanman, Shion Andrew, Daniele Michilli, and Kaitlyn Shin, collaborated with researchers from various institutions to achieve this groundbreaking discovery. Their work opens new avenues for understanding the mysterious origins of FRBs and the extreme environments that produce them.

Investigating Burst Origins

The detection of fast radio bursts (FRBs) has dramatically increased in recent years, thanks to the Canadian Hydrogen Intensity Mapping Experiment (CHIME). This unique telescope array, consisting of four massive stationary receivers shaped like half-pipes, is finely tuned to capture radio signals, particularly those emitted by FRBs.

Since 2020, CHIME has identified thousands of FRBs from across the cosmos. While it’s agreed that these bursts originate from compact objects like neutron stars, their exact mechanism remains a puzzle. Some theories suggest that FRBs arise in the turbulent magnetospheres of compact objects, while others argue they are the result of shockwaves propagating far from the source.

To investigate this mystery, scientists utilized scintillation—an effect where light from a compact, bright object, such as a star, appears to twinkle as it passes through gas in space. The degree of twinkling depends on the size and distance of the source. By studying how an FRB scintillates, researchers can estimate whether it comes from a small, close region near its source or a more distant, expansive area.

Zooming in on FRB 20221022A

The team focused on FRB 20221022A, a signal detected by CHIME in 2022. Lasting about two milliseconds, this FRB was notable for its highly polarized light, which followed a smooth S-shaped curve—a pattern similar to that of pulsars, the rapidly rotating neutron stars in our galaxy. This suggested the burst might have originated near a neutron star.

Using scintillation data, the researchers identified steep variations in the FRB’s brightness, confirming that gas within its host galaxy had bent the radio waves. This gas acted like a lens, allowing the team to pinpoint the source to a remarkably small region, roughly 10,000 kilometers wide.

“This means the FRB is incredibly close to its source, within hundreds of thousands of kilometers,” explained lead author Kenzie Nimmo. “If it originated from a shockwave, we’d expect the signal to come from tens of millions of kilometers away, with no scintillation.”

Kiyoshi Masui, an MIT physicist, highlighted the precision of the findings: “Pinpointing a 10,000-kilometer region from 200 million light-years away is akin to measuring the width of a DNA helix on the moon’s surface.”

Groundbreaking Evidence

The team’s results, supported by complementary findings from McGill University, confirm for the first time that FRBs can emerge from the chaotic magnetospheres surrounding neutron stars. This rules out the possibility that FRB 20221022A originated from a distant shockwave.

“This discovery shows that scintillation is a powerful tool for unraveling the diverse origins of FRBs,” Masui noted. “These bursts occur daily, and understanding their physics will require techniques like this.”

Co-author Ryan Mckinven of McGill University added, “The polarized signal resembled pulsars in our galaxy, which initially led to concerns that the source wasn’t an FRB but a misclassified pulsar. However, optical telescope data confirmed its extragalactic origin.”

The research opens doors for follow-up studies of polarized signals in other FRBs and encourages theoretical work to explain their varied behavior.

This groundbreaking work was made possible through support from institutions such as the Canada Foundation for Innovation, the Dunlap Institute for Astronomy and Astrophysics, the Canadian Institute for Advanced Research, and McGill’s Trottier Space Institute.