A New Class of High‐Mass X‐Ray Binaries: Implications for Core Collapse and Neutron Star Recoil

Abstract

We investigate an interesting new class of high-mass X-ray binaries (HMXBs) with long orbital periods (Porb > 30 days) and low eccentricities (ed0:2). The orbital parameters suggest that the neutron stars in these systems did not receive a large impulse, or ‘‘ kick,’’ at the time of formation. After considering the statistical significance of these new binaries, we develop a self-consistent phenomenological picture wherein the neutron stars born in the observed wideHMXBs receive only a small kick (