X-ray Spectral Formation in Low Mass X-ray Binaries

The spectral properties of the non-pulsing low mass X-ray binaries are reviewed using recent EXOSAT observations. The spectra of the persistent emission from a sample of the lower luminosity, 10³⁷erg/s systems (usually X-ray burst sources), are well modelled by a simple power law attenuated at high energies by an exponential cutoff. The higher luminosity 10³⁸erg/s systems require an additional blackbody component, whose luminosity ranges from 10 to 40% of the total. Various models for the inner region of an accretion disk and its interaction with a neutron star are considered.