Astronomy
The Origins of Fast Radio Bursts from Magnetars
Quick fact
In April 2020, a magnetar named SGR 1935+2154, located about 30,000 light-years away in our Milky Way, was caught emitting a fast radio burst in real time—the first such event ever observed from inside our galaxy.
Why this is interesting
Imagine a flash of radio light that releases in a millisecond more energy than our Sun does in a day—except it comes from a city-sized object. What could possibly produce such a blast?
Read the full explanation
Understanding The Origins of Fast Radio Bursts from Magnetars
Fast radio bursts are intense, brief pulses of radio waves that last only a few milliseconds. They were first discovered in 2007, and their origin remained a puzzle. Some were thought to come from cataclysmic events like merging neutron stars or black holes, but others seemed to repeat—a clue that they could come from a single, surviving object. Magnetars are a type of neutron star, the collapsed core of a massive star after a supernova explosion. They have the most powerful magnetic fields known in the universe, trillions of times stronger than Earth's. The idea was that the enormous magnetic energy of a magnetar could power an FRB through a sudden reconfiguration or 'starquake' of its crust. The 2020 observation gave direct evidence: a magnetar in our own galaxy emitted a burst compared to the bright FRBs seen from other galaxies, though it was somewhat less energetic. This proved that at least some FRBs originate from magnetars.
A deeper explanation
Magnetars are neutron stars with magnetic fields so intense that they can distort atoms and warp the vacuum around them. The energy for an FRB likely comes from the magnetic field itself. When the magnetic field becomes stressed, it can 'snap' and reconnect, similar to the mechanism behind solar flares, but on a vastly more energetic scale. This process can accelerate particles to near-light speed, producing intense radio radiation. The April 2020 event, modeled on SGR 1935+2154, showed a burst with a luminosity consistent with what would be expected from a magnetar, and it was accompanied by a concurrent X-ray burst, confirming the correlation. This discovery not only confirms magnetars as a source of FRBs but also raises questions: Are all FRBs from magnetars? Why do some repeat? What distinguishes the most powerful FRBs? It also turns FRBs into a tool for studying the extreme physics of magnetar magnetic fields and the intergalactic medium through dispersion measures.