A magnetar is a neutron star with an extremely powerful magnetic field (about 100 to 1000 times stronger than the Crab Nebula pulsar), the decay of which powers the emission of copious amounts of high-energy electromagnetic radiation, particularly X-rays and gamma-rays. The theory regarding these objects was formulated by Robert Duncan and Christopher Thompson in 1992. In the course of the decade that followed, the magnetar hypothesis has become widely accepted as a likely physical explanation for observable objects known as soft gamma repeaters and anomalous X-ray pulsars.