X-ray binary pulsars: Pulse vs. orbit and the high-energy continuum

Abstract

Pulse period and binary orbit period in X-ray pulsars have been found to be correlated, depending on the nature of the mass-donor. We have examined the high-energy continua of these sources above 20 keV. We find that Be-star binaries have the hardest spectra, while those of objects accreting by Roche lobe overflow have the softest spectra. The temperatures derived from bremsstrahlung or exponential fits to archival HEAO-A4 all-sky survey data, BATSE and HEXE data of Be and supergiant binaries correlate with the position of the sources on the pulse-period vs. orbit period diagram. © 1995.