The Ohmic decay of dipolar toroidal magnetic fields of magnetars

By considering the general relativity effect, we calculated the dipolar toroidal magnetic field decay rates and investigated the L-X - L-rot relationship of 22 magnetars with soft X-ray luminosities. It is found that, for magnetars with L-X L-rot, the Ohmic decay of crustal toroidal magnetic fields can provide their observed isotropic soft X-ray luminosities and maintain high thermal temperatures.