Abstract Magnetars are proposed to be peculiar neutron stars which could power their X-ray radiation by super-strong magnetic fields as high as ≳1014 G. However, no direct evidence for such strong fields has been obtained till now, and the recent discovery of low magnetic field magnetars even indicates that some more efficient radiation mechanism than magnetic dipole radiation should be included. In this paper, quantum vacuum friction (QVF) is suggested to be a direct consequence of super-strong surface fields, therefore the magnetar model could then be tested further through QVF braking. The high surface magnetic field of a pulsar interacting with the quantum vacuum results in a significantly high spindown rate (). It is found that a QVF dominates the energy loss of pulsars when the pulsar’s rotation period and its first derivative satisfy the relationship P3 > 0.63 × 10−16 ξ−4 s2, where ξ is the ratio of the surface magnetic field over the dipole magnetic field. In the “QVF + magnetodipole” joint braking scenario, the spindown behavior of magnetars should be quite different from that in the pure magnetodipole model. We are expecting these results could be tested by magnetar candidates, especially low magnetic field cases, in the future.
Keywords pulsars: general — radiation: dynamics — stars: magnetars — stars: neutron
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