Greenhill J G , Galloway D K , Murray J R, PASA, 16 (3), 240.
Next Section: Spectroscopic evidence on the
Title/Abstract Page: Angular Momentum Transfer in
Previous Section: Angular Momentum Transfer in
Introduction
The binary X-ray pulsar GX 1+4 is unique in several respects. It is the only known pulsar in a symbiotic system (V2116 Oph), 
per year is the largest measured for any pulsar and the neutron star magnetic field is believed to be
G - the strongest field in the known high mass or low mass X-ray binaries.
The optical spectrum is that of an M giant plus a variable blue continuum and a forest of strong emission lines from H, HeI, FeII, [FeVII], [OIII] etc. The emission lines are believed to arise from photo-electric interactions of accretion disc UV photons in circumstellar matter (Davidsen, Malina & Bowyer, 1977; Chakrabarty & Roche, 1997). The blue continuum is generated by the disc.
The processes of angular momentum transfer in GX 1+4 are poorly understood. A long period of high luminosity and neutron star spin-up was followed by generally lower luminosity and spin-down interrupted by short episodes of spin-up. The average rates of spin-up and spin-down are similar but no clear correlation exists between 
and X-ray luminosity LX. The changes are not consistent with the standard accretion theory model (Ghosh & Lamb, 1979).
In this workshop we investigated recent evidence relating to transitions between spin-up and spin-down in GX 1+4. In chapter 2 we discuss evidence from X-ray and optical spectroscopy concerning the nature and distribution of the circumstellar matter in this system. In chapter 3 we report sudden changes in X-ray pulse profiles associated with changes in LX and probably associated with a brief transition to neutron star spin-up. In chapter 4 we compare the observed relation between LX and accretion torque with numerical simulations based on theoretical models of the accretion disc.
Next Section: Spectroscopic evidence on the
Title/Abstract Page: Angular Momentum Transfer in
Previous Section: Angular Momentum Transfer in
© Copyright Astronomical Society of Australia 1997