|
I discuss the observational evidence for decay of the dipole magnetic field
in so-called magnetar candidates (Soft Gamma Repeaters and Anomalous X-ray
Pulsars) and show that the decaying dipole does not have enough energy to
power the persistent X-ray emission of these sources. The latter must thus
directly reveal the decay of an additional, stronger field component,
presumably hidden in the interior of these neutron stars. Using existing
models it is possible to characterize the salient properties of this
internal field component and their implications for magnetar astrophysics.
Finally, I sketch preliminary considerations on evolutionary links between
magnetars and different classes of neutron stars with strong dipole field
that do not show magnetar-like activity.
|