The evolution of the progenitor system of relativistic binary radio pulsars

Abstract

The relativistic binary pulsars PSR 1913 + 16 and 1534 + 12 are unique among binary pulsars in that their masses are accurately known as a result of studying general relativistic effects arising from their extremely short orbital periods ( ≲ 10 h) and stable pulse periods. In order to produce such binary pulsar systems, the progenitor systems must have lost significant mass and angular momentum via a phase of common-envelope evolution. The survival of such systems requires that they must have, at one time, been long-period ( ~ 2 –3 yr) binaries. Conservative thermal time-scale mass transfer is ruled out as a mechanism for producing such long-period binaries for the progenitors of these relativistic binary pulsars. We develop evolutionary scenarios for PSR 1913 + 16 and 1534 + 12 which provide an understanding of the fact that the observed pulsars are, respectively, the more and less massive neutron stars in their system.