What makes magnetars the most powerful magnets in the universe?

The answer

Magnetars are neutron stars with magnetic fields reaching 10¹¹ Tesla - roughly a quadrillion times stronger than Earth's magnetic field and a thousand times stronger than typical neutron stars. About 30 magnetars are known in our galaxy. Their extreme magnetism is generated during the neutron star's formation when convective dynamo processes amplify the magnetic field within the first 10-20 seconds. Magnetar starquakes - fractures in the neutron star's crystalline crust caused by magnetic stress - release enormous bursts of X-rays and gamma rays. The December 2004 giant flare from SGR 1806-20 released more energy in one-tenth of a second than the Sun emits in 250,000 years, temporarily ionizing Earth's upper atmosphere from 50,000 light-years away. Magnetars are also leading candidates for the source of fast radio bursts, confirmed when magnetar SGR 1935+2154 produced an FRB-like signal in April 2020.