Three‐Dimensional Simulations of the Reorganization of a Quark Star’s Magnetic Field as Induced by the Meissner Effect

In a previous paper (Ouyed et al. 2004) we presented a new model for softgamma-ray repeaters (SGR), based on the onset of colour superconductivity inquark stars. In this model, the bursts result from the reorganization of theexterior magnetic field following the formation of vortices that confine theinternal magnetic field (the \mz effect). Here we extend the model bypresenting full 3-dimensional simulations of the evolution of the inclinedexterior magnetic field immediately following vortex formation. The simulationscapture the violent reconnection events in the entangled surface magnetic fieldas it evolves into a smooth, more stable, configuration which consists of adipole field aligned with the star's rotation axis. The total magnetic energydissipated in this process is found to be of the order of $10^{44}\mathrm{erg}$ and, if it is emitted as synchrotron radiation, peaks typicallyat $280 \mathrm{keV}$. The intensity decays temporally in a way resembling SGRsand AXPs (anomalous X-ray pulsars), with a tail lasting from a few to a fewhundred times the rotation period of the star, depending on the initialinclination between the rotation and dipole axis. One of the obviousconsequences of our model's final state (aligned rotator) is the suppression ofradio-emission in SGRs and AXPs following their bursting era. We suggest thatmagnetar-like magnetic field strength alone cannot be responsible for theproperties of SGRs and AXPs, while a quark star entering the ``Meissner phase''is compatible with the observational facts. We compare our model toobservations and highlight our predictions.Comment: 26 pages, 8 figure