Recently, astronomers have been able to link two seemingly unrelated phenomena: an explosive event known as a fast radio burst and the change in velocity of a spinning magnetar. And now, new research suggests the cause of both is the destruction of an asteroid by a magnetar.
For years, astronomers have puzzled over the origin of fast radio bursts, which are bursts of radio energy lasting less than a second. Since fast radio bursts have been detected in distant galaxies, they must be incredibly energetic events. But it wasn’t until astronomers observed a fast radio burst in our own galaxy that we spotted the likely culprit: magnetars.
Magnetars are a special type of pulsar, which are rapidly rotating neutron stars. When neutron stars first form, they can carry enormously strong magnetic fields – the strongest magnetic fields in the entire universe. And so these supermagnetized neutron stars get a new name: magnetars.
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The connection to fast radio bursts was made when astronomers noticed a magnetar glitch. Magnetars rotate at very precise speeds. But occasionally, that speed can suddenly change so that the speed becomes either slower or faster. Astronomers noticed a flaw in a magnetar around the same time a fast radio burst was generated. Since magnetars carry enormous amounts of energy, they could potentially explain the origin of rapid radio bursts.
While we knew these two processes were linked, we didn’t know what led to it. Now, in new research, a team of astrophysicists have suggested that asteroids have something to do with it.
Asteroids are believed to be common near magnetars. Since magnetars are the remains of giant stars after their death, parts of their solar system remain intact. Therefore, magnetars are likely to be surrounded by a variety of asteroids and other debris. In the scenario designed by the researchers, it can happen that an asteroid moves too close to its magnetar. The Magnetar not only has a strong magnetic field, but also an extremely strong gravitational force. If the asteroid gets too close, gravity can tear it apart.
When the asteroid is ripped apart, its angular momentum has to go somewhere. If it follows a trajectory that aligns with the magnetar’s rotation, it will increase the magnetar’s speed as soon as it is disturbed. This causes the error. If the asteroid is moving in the opposite direction, it will slightly slow down the magnetar, resulting in what is known as an anti-glitch.
Either way, the debris from the torn apart asteroid is now caught in the extremely strong magnetic fields. As a result, the magnetic fields intertwine and release their pent-up energy in the form of a rapid radio burst.
Eventually, the remaining debris eventually rains down onto the magnetar surface, releasing flares of its own that we may be able to spot. It’s a plausible scenario to explain exactly how magnetars can lead to rapid radio bursts, and it shows that even the smallest objects in a solar system, like asteroids, can lead to very large impacts.