Fast Radio Bursts Appear to Be Caused by Young Neutron Stars

Fast Radio Bursts (FRBs) are one of the greater mysteries facing astronomers today, rivaled only by Gravitational Waves (GWs) and Gamma-ray Bursts (GRBs). Originally discovered in 2007 by American astronomer Duncan Lorimer (for whom the “Lorimer Burst“ is named), these shot, intense blasts of radio energy produce more power in a millisecond than the Sun generates in a month. In most cases, FRBs are one-off events that brightly flash and are never heard from again. But in some cases, astronomers have detected FRBs that were repeating in nature, raising more questions about what causes them.

Prior to the discovery of FRBs, the most powerful bursts observed in the Milky Way were produced by neutron stars, which are visible from up to 100,000 light-years away. However, according to new research led by the Netherlands Institute for Radio Astronomy (ASTRON), a newly detected FRB was a billion times more radiant than anything produced by a neutron star. What’s more, this burst was so bright that astronomers could see it from a galaxy one billion light-years from Earth! This finding raises innumerable questions about the kinds of energetic phenomena in the Universe.

The research was led by Inés Pastor-Marazuela, a Rubicon Research Fellow at the Jodrell Bank Centre for Astrophysics and a researcher with ASTRON and the Anton Pannekoek Institute, University of Amsterdam. She was joined by multiple colleagues from ASTRON, the Cahill Center for Astronomy, the National Centre for Radio Astrophysics, the Netherlands eScience Center, the Perimeter Institute for Theoretical Physics, and the Department of Space, Earth and Environment at Chalmers University of Technology. The paper detailing their findings recently appeared in Astronomy & Astrophysics.

The discovery was made using the Westerbork Synthesis Radio Telescope (WSRT) – part of the European VLBI network (EVN) – a powerful radio telescope consisting of 14 steerable 25 m (ft) dish antennas. This observatory relies on a technique called “aperture synthesis” to generate radio images of the sky, enabling astronomers to study a wide range of astrophysical phenomena. After more than two years of observation, the WSRT’s sophisticated instruments and techniques led to the discovery of 24 new FRBs.

These discoveries were made with the help of an experimental supercomputer, the Apertif Radio Transient System (ARTS), specifically designed to study FRBs. This supercomputer analyzed all the radio signals coming from the sky during the observation period, which helped the team deduce where future FRBs would appear. As Pastor-Marazuela said in an ASTRON press release:

“We were able to study these bursts in an incredible level of detail. We find that their shape is very similar to what we see in young neutron stars. The way the radio flashes were produced, and then modified as they traveled through space over billions of years, also agrees with a neutron star origin, making the conclusion even stronger”.

Essentially, the team taught ARTS to look specifically for bursts that are very short, very bright, and from very distant sources. Radio sources that meet all three criteria will likely be the most powerful and fascinating. When ARTS finds such bursts in the data, it autonomously zooms in on the phenomena and informs the astronomers. Said research leader Joeri van Leeuwen from ASTRON:

“We generally do not know when or where the next FRB will appear, so we have a vast computer constantly crunch through all radio signals from the sky. After a while, the resemblance with the flashes we know from highly magnetic neutron stars started to emerge, and we were very excited that we lifted part of the veil around these perplexing bursts. We were just starting to think we were getting close to understanding how regular neutron stars can shine so exceedingly bright in radio. But then the Universe comes along and makes the puzzle one billion times harder. That’s just great”.

While this new mystery is intriguing, the team is also excited that they have been able to link FRBs to young neutron stars for the first time. “It is amazing to work on these distant FRBs, [you] really feel you are studying them up close from a single burst, and find they appear to be neutron stars,” said Pastor-Marazuela.

Further Reading: ASTRON, Astronomy & Astrophysics

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