Understanding the Evolution of Close Binary Systems with Radio Pulsars

BENVENUTO, O. G; DE VITO, M. A.; HORVATH, J. E.

The Astrophysical Journal Letters

IOP Science

Lugar: Bristol; Año: 2014 vol. 786 p. 7 - 9

2041-8205

We calculate the evolution of close binary systems (CBSs) formed by a neutron star (behaving as a  radio pulsar) and a normal donor star, evolving either to helium white dwarf (HeWD) or ultra short orbital period systems. We consider X-ray irradiation feedback and evaporation due to  radio pulsar irradiation.  We show that irradiation feedback leads to cyclic mass transfer episodes, allowing CBSs to be observed in-between as binary radio pulsars under conditions  in which standard, non-irradiated models predict the occurrence of a low mass X-ray binary. This behavior accounts for the existence of a family of eclipsing binary systems known as redbacks. We predict that redback companions should almost fill their Roche lobe, as observed in PSR J1723-2837. This state is also possible for systems evolving with larger orbital periods.  Therefore, binary radio pulsars with companion star masses usually interpreted as larger than expected to produce HeWDs may also result in such "quasi-Roche Lobe Overflow" states, rather than hosting a carbon-oxygen WD. We found that CBSs with initial orbital periods P_{i}