For the first time, astronomers have definitely discovered a flaming magnet in another galaxy.
These ultra-magnetic stellar corpses were believed to be responsible for the highest-energy explosions in the nearby universe. But until this outbreak, no one could prove it, astronomers reported Jan. 13 at the American Astronomical Society's virtual meeting and in work on Nature and Nature Astronomy.
Astronomers have seen magnets floating in the Milky Way, but they are so bright that it is impossible to take a good look at them. Possible glimpses of magnetars in other galaxies could also be glimpsed earlier. But “the others were a bit circumstantial and not as solid as rock,” says astrophysicist Victoria Kaspi of the McGill Space Institute in Montreal, who did not participate in the new discovery. "Here's something so incontrovertible, it's like, it's okay. No doubt about it."
The first signal from the magnet arrived as an X-ray and gamma-ray burst on April 15th. Five telescopes in space, including the gamma-ray Fermi space telescope and the Mars Odyssey orbiter, observed the explosion, giving scientists enough information to track it. by its source: the galaxy NGC 253 or the galaxy Sculptor, 11.4 million light-years away.
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At first, astronomers thought the explosion was a type of cataclysmic explosion called a short gamma-ray burst or GRB, which is usually caused by colliding neutron stars or other destructive cosmic events.
But the signal seemed strange for a short GRB: it rose to rapid brightness in two milliseconds, was delayed by another 50 milliseconds, and seemed to have surpassed about 140 milliseconds. When the signal faded, some of the telescopes detected fluctuations in light that changed faster than a millisecond.
Typical short GRBs that result from a neutron star collision do not change that way, said astrophysicist Oliver Roberts of the University Space Research Association in Huntsville, Alabama. enters and leaves sight as the magnet rotates.
Then, surprisingly, the Fermi telescope captured gamma rays with energies greater than a gigabyte electronvolt arriving four minutes after the initial explosion. There is no way for known short GRB sources to do this.
"We discovered a magnet disguised in a nearby galaxy and unmasked it," astrophysicist Kevin Hurley of the University of California, Berkeley said in a Jan. 13 news release.
A scorching magnet sent an explosion of light (magenta) and particles (cyan) through space, as shown in this animation. Astronomers think the interaction between those particles and the environment around the magnet could help explain the strange appearance of the explosion.
Researchers think the outbreak was triggered by a tremendous earthquake, a trillion trillion, or 1027, times larger than the magnitude 9.5 earthquake recorded in Chile in 1960. "I'm from California, and out here we would definitely call it or big, "Hurley said. The earthquake led the magnet to release a plasma stain that drifted away at almost the speed of light, emitting gamma rays and X-rays as it advanced.
The finding suggests that at least some signals that look like short GRBs are in fact coming from magnetic flares, as astronomers have long suspected (SN: 03/11/10). It also means that three previous events that astronomers had marked as possible magnet flares probably came from magnetized stellar corpses, giving astronomers a population of magnet flares to compare to each other.
The finding could have exciting implications for the rapid bursts of radio, another mysterious cosmic sign that has led astronomers to scratch their heads for more than a decade. Several lines of evidence connect fast radio bursts with magnets, including another signal from the Milky Way that coincidentally also arrived in April 2020 (SN: 4/4/20).
“That (discovery) supported the additional credibility for fast radios to be (de) magnetic,” Kaspi says, though there are still issues with that theory.
Kaspi compared the apparent frequency of magnet flares in other galaxies with the frequency of rapid radio bursts and found that the rates are similar. “That argues that in reality, most or all of the fast radio bursts could be magnetic …. I don’t think it’s the total solution,” but it’s a good move, he says.