Astronomers have known about fast radio bursts (FRBs) for a while now, but their origin has been puzzling. Now, they have solved the cosmic mystery.
Powerful fast radio bursts are intense flashes of radio emission that only last a few milliseconds.
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You can produce this sort of sudden surge of energy by destroying something. But the existence of repeating sources suggests that at least some of them are produced by an object that survives the event. That has led to a focus on compact objects, like neutron stars and black holes, with a class of neutron stars called magnetars being viewed very suspiciously.
For about 13 years, scientists have received FRBs coming from outside our galaxy. This made it harder to trace them back to what’s causing them.
However, on April 28 this year, multiple telescopes detected a bright FRB from the same area within our Milky Way. And this is when astronomers pinned down the source: Galactic magnetar SGR 1935+2154.
Magnetars are young neutron stars that are the most magnetic objects in the universe. These objects have long been prime suspects in the hunt for the source of these radio bursts.
But this discovery marks the first time that astronomers have been able to directly trace the signal back to a magnetar.
Two different telescopes spotted these FRBs: one a California doctoral student’s set of handmade antenna’s, which included actual cake pans, and the other a $20 million Canadian observatory.
The magnetar lies 32,000 light-years from Earth, according to four studies in Wednesday’s journal Nature.
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These dense neutron stars have 1.5 times the mass of our sun squeezed into a region the size of Manhattan.
Neutron stars are best known for powering pulsars, rapidly repeating bursts of radiation driven by the fact that these massive objects can complete a rotation in a handful of milliseconds.
Magnetars, on the other hand, tend not to rotate as quickly but have intense magnetic fields, about a trillion times stronger than the Earth’s magnetic field.
The magnetic field around these magnetars is so strong that they can distort the orbiting electrons in atoms.
Scientists identified them by their semi-regular production of high-energy X-rays and low-energy gamma rays, giving them the name “soft gamma-ray repeaters,” or SGR.
Christopher Bochenek, whose Survey for Transient Astronomical Radio Emission 2 (STARE2) in the US was one of the teams to spot the burst, said that in approximately a millisecond the magnetar emitted as much energy as the Sun’s radio waves do in 30 seconds.
Scientists compared this energy to FRBs from outside the galaxy. Thus, strengthening the case for magnetars to be the source of most extragalactic bursts.
People have had different theories for what causes these fast radio bursts, including aliens. Some astronomers say magnetars may not be the only answer, especially since there seem to be two types of fast radio bursts. FRBs like the one spotted in April, happen only once, while others repeat themselves often.
Since finding these bursts is extremely hard, tracking even one of them is a welcome surprise and an important finding.
These bursts, however, don’t pose any threats to us.