1207.0096 (H. Tong et al.)

Revised spin down of SGR 0418+5729: a no longer so low dipole magnetic field?    [PDF]

H. Tong, R. X. Xu

The spin down behaviors of SGR 0418+5729 are investigated. The pulsar spin down model of Contopoulos & Spitkovsky (2006) 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 SGR 0418+5729 may be a low magnetic field magnetar. However, it may also have a strong dipole magnetic field, if there is a small magnetic inclination angle. This result is obtained under the general assumption that its braking mechanism is similar to that of rotation-powered pulsars. 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.

View original: http://arxiv.org/abs/1207.0096