2012ApJ...757L..10T

The spin-down behaviors of SGR 0418+5729 are investigated. The pulsar spin-down model of Contopoulos and Spitkovsky is applied to SGR 0418+5729. It is shown that SGR 0418+5729 lies below the pulsar death line and its rotation-powered magnetospheric activities may therefore have stopped. The compact star is now spun down by the magnetic dipole moment perpendicular to its rotation axis. Our calculations show that under these assumptions there is the possibility of SGR 0418+5729 having a strong dipole magnetic field, if there is a small magnetic inclination angle. Its dipole magnetic field may be much higher than the characteristic magnetic field. Therefore, SGR 0418+5729 may be a normal magnetar instead of a low magnetic field magnetar.