On the magnetic field evolution timescale in superconducting neutron star cores

Understand

We revisit the various approximations employed to study the long-term evolution of the magnetic field in neutron star cores and discuss their limitations and possible improvements.

• A recent controversy on the correct form of the induction equation and the relevant evolution timescale in superconducting neutron star cores is addressed and clarified.
• We show that this ambiguity in the estimation of timescales arises as a consequence of nominally large terms that appear in the induction equation, but which are, in fact, mostly irrotational.
• This subtlety leads to a discrepancy by many orders of magnitude when velocity fields are absent or ignored.