All neutron stars have intense magnetic fields. The typical magnetic field of a neutron star is about 100,000 times stronger than the strongest magnetic fields we can create on Earth. But about 1% of neutron stars have even stronger magnetic fields. Known as magnetars, their magnetic fields can be 1,000 times stronger than a regular magnetic field. They are a likely cause for powerful transient events such as soft gamma-ray repeaters and fast radio bursts. A new study looks at how magnetars might form.

The work focuses on the mergers of binary neutron stars. Often when two neutron stars collide they form a black hole. This is because the combined mass of the two neutron stars is greater than the Tolman-Oppenheimer-Volkoff (TOV) limit, which is around 2.6 solar masses. Most neutron stars are more massive than white dwarfs, which have a Chandrasekhar limit of about 1.4 solar masses. But some neutron stars have smaller masses.…