Primary goals of the Rossi X-ray Timing Explorer's large area were significant measurements on timescales below a millisecond, which are required to study the possible variations of neutron stars and stellar black hole candidates. A majority of active low-mass X-ray binaries are believed to be neutron stars which have accreted as much as several tenths of a solar mass over a long stellar lifetime. RXTE discoveries of nearly coherent oscillations in the flux from neutron stars heated by thermonuclear flashes indicate they have been spun up to periods of 2-3 milliseconds. Discovery of one accreting millisecond pulsar has shown the existence of speculated progenitors to millisecond radio pulsars; more are being sought among transient bursters of similar low luminosities. In a large number of the low-mass X-ray binaries, kilohertz signals in the persistent flux reveal plasma circulating the neutron star as if constrained by the general relativistic minimum stable orbit. Alternative interpretations of the signatures and how they originate continue to be investigated. I will review the discoveries and their exciting potential for determining the effects of general relativity in the neutron star gravitational fields, which are second only to those of black holes.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1999