X-ray spectral survey of WGACAT quasars. II. Optical and radio properties of quasars with low-energy X-ray cutoffs

We have selected quasars with X-ray colors suggestive of a low-energy cutoff, from the ROSAT Position Sensitive Proportional Counter (PSPC) pointed observations archive. We examine the radio and optical properties of these 13 quasars. Five out of the seven quasars with good optical spectra show associated optical absorption lines, with two having high Av candidate systems. Two other cutoff quasars show reddening associated with the quasar. We conclude that absorption is highly likely to be the cause of the X-ray cutoffs, and that the absorbing material is associated with the quasars, not intervening along the line of sight. The suggestion that gigahertz peaked sources are associated with X-ray cutoffs remains unclear with this expanded sample.