Astronomers trace mysterious space radio waves to a source in our galaxy


In April, a group of astronomers spotted a short, powerful burst of radio waves coming from outer space, then managed to find where it came from: a powerful object in our own galaxy. It’s the first time scientists have been able to identify these mysterious radio waves originating from inside the Milky Way, making them the closest of a kind we’ve ever seen.

The radio waves – known as fast radio bursts, or FRBs – appear to have sprouted from an incredibly powerful “zombie” star lurking in our galaxy, according to three papers in the journal Nature. Called a neutron star, the object is a super-dense remnant that forms when a massive star, larger than our own Sun, collapses in on itself. But this neutron star is what is called a magnetar. It hosts an incredibly powerful magnetic field that stores mind-boggling amounts of energy capable of warping the shape of atoms.

The search for the source of this FRB is a big moment for astronomers, who are eager to understand how these mystifying radio flashes come about. FRBs are thought to appear once per second in the night sky, blazing for a few milliseconds at a time. But we’ve only seen a tiny fraction of these phenomena in play, and all the gusts we have have vus apparently originate from outside our galaxy, with some located billions of light-years away. It is therefore difficult to determine exactly where they come from. “These are these very mysterious signals, and we don’t have a very good idea what’s producing them or what the physics is behind,” said Kiyoshi Masui, an assistant professor of physics at MIT who worked on the discovery. . The edge.

Now, with this discovery, astronomers have a much closer source to work with. The magnetar is located only 30,000 light years away – in our own backyard, cosmically speaking. And that indicates a strong connection between magnetars and these dynamic space radio waves. “It’s the missing link,” says Masui. “Now we’ve seen a fast radio burst from a magnetar, so this proves that at least some of the fast radio bursts we see in the universe come from magnetars.”

Scientists have been trying to track down the origins of FRBs since the first one was detected in 2007. But because FRBs are so fleeting, spotting them has often required looking in the right place at the right time with the right equipment. Astronomers were lucky when they found a few FRBs that seem to repeat themselves, flashing over and over in the same part of the sky. These recurring bursts have helped scientists locate the galaxies from which these radio waves originate. Yet it is unclear exactly which objects within these galaxies produce the FRBs.

This is why this discovery is so crucial. Two different observatories in North America — CHIME in Canada and STARE2 in the United States — spotted this FRB coming from the same part of the sky, bolstering the credibility of the signal. The FRB was also incredibly bright. In fact, a cellphone 4G LTE receiver would have been able to pick up the signal coming from the other side of the galaxy, according to Christopher Bochenek, a graduate student in astronomy at Caltech who led the STARE2 discovery team.

“When I first looked at the data, I froze and was basically paralyzed with excitement,” Bochenek said on a press call.

The timing and location of the flash matched another cosmic event occurring nearby. Just days before the FRB was detected, astronomers noticed that a known magnetar had become quite hyperactive in the sky, sending out X-rays and gamma rays. After analyzing the FRB data, CHIME and STARE2 astronomers confirmed that the radio waves had coincided with a particularly large burst of X-rays from the magnetar. The discovery already made waves in the astronomy community earlier this year, with the first scientific reports of the connection published online and covered in the media. The researchers’ results have now been reviewed by other scientists and are officially presented in the journal. Nature this week.

Magnetars could make for a very good origin story for many FRBs. Scientists suspect that these dead magnetic stars could be behind radio flashes for quite some time, as they are full of energy and capable of sending out bursts of different types of light for fractions of a second. “So this finding paints a picture that some and perhaps most – given the frequency of these events in the universe – fast radio bursts from other galaxies come from magnetars,” Bochenek said.

But astronomers are yet to proclaim the mystery behind the solved FRBs. For one thing, astronomers continued to monitor the magnetar as it emitted more X-rays and gamma rays, but these tracking events did not match any significant radio wave bursts. Additionally, this burst was still relatively weak compared to other FRBs we’ve seen. It’s actually 1,000 times fainter than the weakest FRB spotted outside our galaxy. Thus, the mechanisms involved are still not fully understood.

The good news is that astronomers have some very good suspects to probe. Not only can they continue to study this magnetar, but there are about 30 other known magnetars that will likely receive a lot of extra attention now. And astronomers could focus on finding FRBs in other galaxies where magnetars are suspected. This could give us a better understanding of whether this event was an offshoot – or the final piece of the FRB puzzle.

“We still don’t know exactly how lucky we were,” says Bochenek. “It could be like a once-in-five-year thing. Or there could be a few of these things happening every year. But with more happenings, we’d be able to tell exactly how lucky we were.


Comments are closed.