MYSTERY WIRE — A flash of luck has helped astronomers solve a recent cosmic mystery: What causes powerful but fleeting fast radio bursts that zip across the universe in a blur usually too quick to track.
Scientists have only known about these energetic pulses called fast radio bursts for about 13 years now a new study sheds new light on the phenomenon.
This is what astronomers at McGill University and California Institute of Technology (Caltech) saw on the 28th of April this year.
It’s what astrophysicists call a fast radio burst (FRB) coming from a magnetar, a neutron star with a much stronger magnetic field than ordinary neutron stars.
It was seen by several space telescopes including one on the International Space Station.
Until now these FRBs have only been seen coming from only outside our galaxy, but they happen so fast, a couple of milliseconds, that they had not been tracked.
But this was a rare but considerably weaker burst coming from inside the Milky Way.
It was spotted by two very different telescopes. The first was McGill University’s 20 million (USD) high tech observatory, the Canadian Hydrogen Intensity Mapping Experiment (CHIME).
CHIME’s principal investigator Professor Victoria Kaspi says: “Magnetars are quite well studied in our own galaxy, so to see something that we know produce something so incredibly bright right next to us, we know that if we could take it and put it in a distant galaxy, we’d still be able to see it. So that tells us all those mysterious sources that are so far away could be magnetars.”
CHIME tracked that fast radio burst to a weird type of star called a magnetar that’s 32,000 light-years from Earth, in a different part of the Milky Way according to four studies just published in the journal Nature today (4 November 2020).
It was not only the first ever fast radio burst traced to a source, but the first emanating from our galaxy.
Astronomers say there could be other types of causes for these bursts, but they are now sure about one guilty party: Magnetars.
Magnetars are incredibly dense neutron stars.
They’re around 1.5 times the mass of our sun squeezed into a space the size of Manhattan.
They have with enormous magnetic fields which buzz and crackle with energy.
Sometimes flares of x rays and radio waves burst out of them.
“Knowing that some could be, are likely to be magnetars is first of all, it makes us you know even more curious. Are we going to see repeats from other sources? Because perhaps that will mean they’re all magnetars, although it will prove it, but also more importantly, we know magnetars produce x rays when they burst, they also produce bursts of x rays and in fact, the event we saw was seen with x ray telescopes as well,” says Kaspi.
According to Kaspi: “It gives tremendous motivation to now go and look at the locations on the sky of comparatively nearby fast radio burst sources, it’s still well outside our galaxy, but relatively close, in the hope that maybe we’ll see x ray bursts from them also and that would be another smoking gun that proves those sources are also magnetars.”
The other observatory to spot the FSB was hand made by Christopher Bochenek a doctoral student at California Institute of Technology (Caltech).
“In a millisecond, this magnetar emitted as much energy in radio waves as the sun does in 30 seconds,” says Bochenek.
Bochenek is part of the Survey for Transient Astronomical Radio Emission 2 (STARE 2) project.
His DIY telescopes are very different from the ones at McGill.
He explains: “The idea behind STARE2 was to find a galactic fast radio burst or something like it and in order to do that, we knew that a galactic fast radio burst would likely be incredibly bright, so we didn’t need a very sensitive receiver and in fact, our receiver is made out of the six inch metal pipe and two actual cake pans. So it’s not a very big, impressive looking thing.
Bochenek explains the telescopes are geared to search for FRBs.
He says: “We get to look at about a quarter of the sky all the time, and that’s really the heart, that’s really the advantage of a telescope like STARE2 is that a fast radio burst in the Milky Way is likely to be both extremely bright and extremely rare. So if you are not sensitive to most of the sky, it’s likely that you would just miss the event because you’re not pointing at the right place at the right time.”
According to Bochenek this outburst in less than a second contained about the same amount of energy that our sun produces in a month and it’s maybe thousands of times weaker than the radio bursts that we notice from outside our galaxy.
Scientists think these are so frequent that could happen more than 1,000 times a day outside our galaxy.
But finding them isn’t as easy as it sounds because they don’t last.
Bochenek figured he had maybe a 1-in-10 chance of spotting a fast radio burst in a few years. But after one year, he got lucky.
The Canadian observatory in British Columbia is more focused and refined but is aimed at a much smaller chunk of the sky, and it was able to pinpoint the source to the magnetar in the constellation Vulpecula.
Commenting on the studies astrophysicist Dr. Jason Hessels says: “Through studying fast radio bursts, I think we can really come to a deeper understanding of the formation of galaxies both in cosmic past and also into the cosmic future, which is really quite important for for us as human beings, because it’s really fundamental to understanding why are we here in the first place? We live on a planet which is orbiting the star, that star lives in the galaxy, but where did all of these things come from? And these are fundamental questions in astronomy and cosmology how was the universe formed and how did the structures that we observe in the universe, galaxies and stars and planets how did they come to be? And of course, we want to understand that because we want to understand where do we come from.”
Astronomers have had as many 50 different theories about what causes these fast radio bursts, including aliens, and they emphasize that magnetars may not be the only answer, especially since there seem to be two types of fast radio bursts.
Some like the one spotted in April happen only once, others repeat themselves often.
Some of these young magnetars are only tens of years old giving them enough energy to produce repeating fast radio bursts.
They may eventually tell us a great deal more about our universe.