The Anomalous X-ray Pulsars ( AXPs ) and Soft Gamma-ray Repeaters ( SGRs ) are a class of pulsars understood as neutron stars ( NSs ) with super strong surface magnetic fields , namely B \gtrsim 10 ^ { 14 } G , and for that reason are known as Magnetars . However , in the last years some SGRs/AXPs with low surface magnetic fields B \sim ( 10 ^ { 12 } -10 ^ { 13 } ) G have been detected , challenging the Magnetar description . Moreover , some fast and very magnetic white dwarfs ( WDs ) have also been observed , and at least one showed X-Ray energy emission as an ordinary pulsar . Following this fact , an alternative model based on white dwarfs pulsars has been proposed to explain this special class of pulsars . In this model , AXPs and SGRs as dense and magnetized white dwarfs can have surface magnetic field B \sim 10 ^ { 7 } -10 ^ { 10 } G and rotate very fast with frequencies \Omega \sim 1 rad/s , consistent with the observed rotation periods P \sim ( 2 - 12 ) s .