The squeezed magnetosphere: spin evolution of accreting neutron star, magnetic field decay and kHz QPOs
Neutron stars in low mass X-ray binaries seem to be the X-ray progenitors of the weakly magnetized millisecond radio pulsar. Although the overall theoretical picture is quite secure, several points are still open. We demonstrate how the decay of the magnetic field plays a key role in the whole scenario. In particular the kHz QPOs, recently detected in several low mass X-ray binaries, suggest the presence of a magnetosphere squeezed against the neutron star surface by the pressure of the accretion flow. Moreover there are indications that some of the neutron stars in these systems have accreted substantial amount of mass resulting in an object spinning close to its centrifugal limit, below one millisecond. A semi-analytical relativistic model for studying the evolution of the spin period of a magnetic neutron star as a function of the accreted mass is discussed. This code is used to explore the proposed evolutionary models.
19th Texas Symposium on Relativistic Astrophysics and Cosmology
- Pub Date:
- December 1998