Generating neutron-star magnetic fields: three dynamo phases

Abstract

Young neutron stars (NSs) have magnetic fields $B$ in the range $10^{12}-10^{15}$ G, believed to be generated by dynamo action at birth. We argue that such a dynamo is actually too inefficient to explain the strongest of these fields. Dynamo action in the mature star is also unlikely. Instead we propose a promising new precession-driven dynamo and examine its basic properties, as well as arguing for a revised mean-field approach to NS dynamos. The precession-driven dynamo could also play a role in field generation in main-sequence stars.

arXiv comment5 pages, 1 figure. Matches version published in MNRAS Letters: figure added since v1, and various parts rewritten for clarity, but arguments unchanged

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