Astronomers Might Finally Know the Source of Fast Radio Bursts
We know much more about how the universe works today than we did just a few decades ago, but there will always be new mysteries to solve. In recent years, scientists have puzzled over the riddle of fast radio bursts (FRBs). These short-lived electromagnetic beacons can outshine entire galaxies, and we haven’t been able to figure out what causes them. A trio of new studies report on an FRB within our own galaxy. Because this one was so much closer than past signals, scientists were able to track it to a particular type of neutron star known as a magnetar.
Despite the immense amount of energy emitted during an FRB, scientists didn’t know they existed until 2007. That’s when a team discovered the first FRB hiding in data acquired back in 2001. Since then, astronomers have spotted numerous FRBs throughout the cosmos. However, this phenomenon seemed to be non-repeating until the discovery of FRB 121102. We now believe this radio source operates on a 157-day cycle, which makes it easier to study.
With the data from FRB 121102, magnetars merged as a plausible candidate. Like pulsars, magnetars are a subset of neutron stars. They don’t spin as quickly as a pulsar, but they have an incredibly intense magnetic field. At about a trillion times as strong as Earth’s magnetic field, a magnetar can disrupt the electron orbitals in molecules, essentially halting chemistry in any normal matter that gets too close.
That brings us to SGR 1935+2154, a magnetar about 30,000 light-years away. That’s not close by any means, but it’s still inside the Milky Way. Back in April, this dead star woke up and began firing off high-energy photons, which was normal. However, two instruments were on the hunt for FRBs at the same time, and that’s what they found exactly when SGR 1935+2154 lit up the sky. Both the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and Survey for Transient Astronomical Radio Emission 2 (STARE2) detected an FRB from this object.
We can’t call this one solved quite yet, though. As the researchers point out in the papers, the apparent FRB from SGR 1935+2154 was only about one percent as powerful as the FRBs we’ve seen from outside the galaxy. It’s possible only very young and energetic magnetars can produce bursts visible from a few galaxies away. Perhaps SGR 1935+2154 is displaying the same phenomenon at a lower level of power. If the team can prove that this object produced FRBs, we can refine our models and hopefully mark this one down as solved.