Millisecond Pulsars Were Born Spinning Fast

Abstract

Occam’s Razor Principle is invoked to explain the high spin rates and low surface magnetic field strengths of millisecond pulsars. The simplest explanation is that these objects were born as rapid rotators owing to conservation of angular momentum during core collapse of the presupernova star. It is shown that conservation of magnetic flux during core collapse leads to surface magnetic fields having the weak strengths ≈ 10⁸ G observed for the newlyborn pulsar in supernova 1987 A.