Binary pulsars before spin-up and PSR 1820 - 11

Abstract

We argue that PSR 1820-11 may be a young pulsar, with a main-sequence companion, and that the system is the progenitor of a low-mass X-ray binary, rather than the descendant of one. If it is not, such a system should soon be found. The small number of antediluvian binary pulsars suggests that most, but not all neutron stars have some torque decay after birth.