Browsing through a pile of data from a radio telescope in 2007, Duncan Lorimer, an astrophysicist at West Virginia University, discovered something was out of the ordinary. Data obtained six years earlier showed a brief, energy burst that lasted no more than 5 milliseconds. Others have seen the light spot and looked through it, but Lorimer and his team calculated that it was a completely new phenomenon: a signal coming from somewhere far outside the Milky Way.
The team doesn’t know what caused it, but they publish their results in Science. The mysterious signal was called a “rapid radio explosion,”; or FRB. In the 13 years since Lorimer’s discovery, dozens of FRBs have been discovered outside the Milky Way – some repeats and others a single, ephemeral cry. Astrophysicists were able to accurately identify their home galaxies, but they struggled to identify the culprits of the universe, coming up with all sorts of theories, from exotic physics to cultures. alien intelligence.
On Wednesday, a trio of studies in the journal Nature describing the origin of FRB was first discovered in The Milky Way, revealing the mechanism behind at least some high-energy radio explosions.
The newly described explosion, dubbed FRB 200428, was discovered and located after it emitted radio antennas in the United States and Canada on April 28, 2020. A hunt was on afterward. Meanwhile, with research groups around the globe focusing on FRB research on the electromagnetic spectrum. It was quickly determined that FRB 200428 was the most energetic radio pulse ever discovered in our home galaxy.
In the new set of documents, astrophysicists outline their detective work and groundbreaking observations from a handful of terrestrial and space telescopes. Linking the observations together, the researchers pinned FRB 200428 into one of the universe’s most unusual wonders: a magnet, the superparamagnetic remainder of a dead supergiant star.
This is the first time astrophysicists have been able to find the culprit in intergalactic planets – but this is only the beginning. “There is really much more to learn in the future,” said Amanda Weltman, an astrophysicist at the University of Cape Town and author of an article in the Nature journal accompanying the discovery.
“This is just an interesting first step.”
Bearing AP force
To understand where FRB 200428 starts, you have to understand where a star ends.
Stars many times larger than the sun are known to experience a chaotic death. After they run out of fuel, physics conspire against them; Their enormous size puts immeasurable pressure on their cores. Gravity forces the star to fold on its own, causing an explosion that releases large amounts of energy in an event known as a supernova.
The star’s crumpled core, born under tremendous pressure, is left behind. Except now it is very small, about the size of a city and about 1 million times denser than Earth. This zombie star is known as a neutron star.
Some neutron stars have extremely strong magnetic fields, about 1,000 times stronger than typical neutron stars. They are a mysterious and attractive class to themselves. Astronomers call them “magnets”, and they are just as curious as FRBs, with only about 30 discovered so far.
One such magnet in the Milky Way, officially named SGR 1935 + 2154, refers to its position in the sky. To make things even easier, name it Mag-1. It was first discovered in 2014 and is located about 30,000 light years from Earth. On April 27, 2020, NASA’s Neil Gehrels Swift Observatory and NASA’s Gamma Fermi-ray Space Telescope obtained a mutation of X-rays and gamma rays emitted from Mag-1.
The next day, two giant North American telescopes – Canada’s hydrogen intensity mapping experiment (CHIME) and Transient Interstellar Radio Emission Survey 2 (STARE2) – obtained an incident. Extremely energetic radio explosions come from the same region of space: FRB 200428. FRB and Mag-1 are located in the same galactic region. Or rather, they appear to be in the same galaxy house.
“These observations point to the magnet as an FRB suction gun,” said Lorimer, lead author on the detection of the first radio explosion in 2007. In the past, magnets had been theorized to be a potential source of FRB, but the data provided evidence that directly linked the two cosmic phenomena.
However, just co-locating the explosion with a magnetic field doesn’t explain at all.
“The magnets sometimes produce X-rays of light,” said Adam Deller, an astrophysicist at Swinburne University in Melbourne, Australia, “but most magnets never emit any radiation. any radio.
Don’t stop me now
Linking the Mag-1 to the FRB 200428 is just the beginning of a long-term investigation.
In the whodunite universe, astronomers have found the culprit, but they’re not exactly sure what the killer weapon is.
Researching the FRB, the researchers were able to identify it as having a high energy but pale color compared to some previously discovered deep space FRBs. “It shines on nearly the weakest FRBs we’ve ever detected,” said Marcus Lower, a PhD in astronomy. at Swinburne University studying neutron stars. This shows that the magnet could be responsible for some FRBs but not all of them – some seem too energetic to be produced in the same way as FRB 200428.
Another article in the journal Nature on Wednesday showed that researchers used China’s five hundred meter aperture Spherical Radio Telescope (FAST) to study Mag-1 in one of the outbreaks. its X-rays. The telescope does not collect any radio emissions from the magnet during its flare. That means it is unlikely that such flare-ups are, alone, responsible for the creation of high-energy FRBs. “It is safe to assume that not every magnetic X-ray explosion will emit an accompanying radio burst,” Deller said.
Deller also noted that FRB 200428 showed features similar to those seen in repeat FRB from outside the Milky Way.
This is important because astronomers have now observed two types of FRBs in other galaxies. Some things flashed vividly and disappeared, and others seemed to repeat themselves at regular intervals. The FRB 200428 looks like a repeater, but is much weaker. Further observations with the CHIME telescope in October uncovered more radio explosions from magnets, although the work has yet to be announced.
Overall, there are some uncertainties. “We cannot say for certain whether the magnetic fields are the source of all the FRBs observed so far,” Weltman noted.
Another question: How did Mag-1 create FRB? Two different mechanisms have been proposed.
One suggestion is that the magnetic fields produce radio waves just as they do the X-rays and gamma rays in their magnetosphere, an extremely large region of the magnetic field around the star. The other is a bit more complicated. “Magnetic fields can live in a cloud of surrounding matter from previous currents,” said Adelle Goodwin, an astrophysicist at Curtin University who is not affiliated with the study. Goodwin noted that this matter cloud could then be hit by an explosion of X-rays or gamma rays, which converts energy into radio waves. Those waves then travel through space and ping the Earth’s detectors as an FRB.
It’s unclear what mechanism led to FRB 200428 – or if something more bizarre could be happening. Other researchers suggest that FRB could even be produced by asteroids stabbed into a magnet, for example. But one thing now seems certain: it’s not alien civilizations trying to get in touch with us. So sorry.
Radio Station Station
Much work remains to be done to unravel the mystery of fast radio explosions.
For Deller, the hunt continued. Part of his job is to focus Where FRB is derived. He says his team still needs to collect more data, but it’s likely that the repeating FRBs might exist otherwise. types galaxies from FRBs do not repeat. Weltman notes that the search for other signals will also intensify, with astronomers looking for electromagnetic radiation and neutrinos produced from any FRB generated by a magnetic field.
Ultimately, the investigation will change the way we view the universe. Duncan Lorimer noted that if FRB could be reliably linked with neutron stars, it would provide a way to do a census of those extreme cosmic entities. Current methods are unable to identify types of neutron stars with high specificity – but FRB can change that. And the FRB is changing the way we see things. A study published in Nature earlier this year used the FRB to solve a decades-long problem about the “missing matter” of the universe.
Lorimer said many of the predictions his team made after discovering the first FRB in 2007 “have been realized in some way” and that he always hopes FRB can become part of the trend. main. As the mysteries deepened, they exceeded his expectations. They have become one of the most confusing but fascinating phenomena in astrophysics.
“It continues to be a fascinating adventure,” he said.
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