Recent Observations of X-Ray Emission from Galactic Binary Neutron Stars

Abstract

Recent measurements of young accreting binary neutron stars are determining more precise magnetic field and accretion parameters. A low magnetic field accreting, millisecond pulsar has finally been found in a binary burster. At least 20 low-mass binaries have exhibited high frequency oscillations, 300--1200 Hertz. The majority have, for some range of luminosity, the pair of quasiperiodic oscillations that have never been seen in a black hole candidate. Recent evidence from burst oscillations strengthens the case that the difference frequency of this pair is close to the spin frequency of the neutron star. These oscillations are correlated with the spectra, luminosity, and low frequency oscillations. Quasiperiodic oscillations are also seen sometimes in strong magnetic field pulsars, where their origin can be closely examined.