Ultra-Soft Excesses in the Soft X-Ray Spectra of Quasars

A survey of the soft X-ray slopes of quasars observed with the IPC on the Einstein observatory has been completed. The fitted X-ray column density towards these objects was found to be systematically lower than that of the galaxy. A similar sample of BL Lac objects does not show such a deficit. This effect is interpreted as due to an excess of emission in the quasar spectra present in the lowest energy channels of the IPC (≤0.28 keV). Identification with the high energy tail of the blue bump is suggested.