Daniele Viganò, Jose A. Pons
Recent observations of neutron stars near the center of Supernova remnants seem to point to magnetic fields (MFs) significantly lower (less than about 1e11 G) than those of normal pulsars. This has led to speculation about the nature of these objects in two opposed directions: anti-magnetars (neutron stars born with low MFs) or hidden magnetic field scenario (neutron stars with strong, buried, sub-surface MF). In this paper, we present the first 2D simulations of the submergence and reemergence of the MF in the crust of a neutron star. A post-supernova accretion stage of about 1e-4 - 1e-3 solar masses is required to deeply bury the MF, if this occurs in a spherically symmetric way. Strongly anisotropic accretion (concentrated on the polar or equatorial regions) has more moderate effects. When accretion stops, the field reemerges on a timescale that depends on the submergence conditions, varying between 1 and 100 kyr. We conclude that the hidden magnetic field model is viable as alternative to the anti-magnetar scenario, but it needs a relatively large accreted mass immediately following the supernova explosion.
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http://arxiv.org/abs/1206.2014
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