On the Bimodal Magnetic Field Distribution of Binary Pulsars

Abstract
We combine the idea of movement of magnetic flux tubes in the stellar interiors with the analysis of crustal physics of accreting neutron stars in low- and high-mass X-ray binaries to explain the bimodal magnetic field distribution of binary pulsars. We propose that this distribution may result from different crustal properties of neutron stars with different accretion rates and amounts of accreted matter. In addition, we may provide an explanation for why the magnetic field strengths of millisecond pulsars with low-mass companions saturate at ~3 × 108 G when accreted mass exceeds ~0.5 M.