The soft X-ray excess in Einstein quasar spectra.

The authors study the soft X-ray excess component for a signal-to-noise (S/N) limited sub-sample of 14 quasars taken from the WE87 sample observed with the Einstein IPC. Detailed analysis of the IPC data, combined with Einstein MPC data where possible, and use of accurate Galactic N_H values allows to estimate the strength of any excess and to improve constraints on the spectral slope at higher X-ray energies. The authors find a significant excess in 9 of the 14 objects, confined in all but one case to below 0.6 keV and variable in the two cases where there are multiple observations. They investigate the relation of the soft excess to other continuum properties of the quasars.