BeppoSAX and ASCA observations of the nearby ( z = 0.184 ) , high–luminosity , radio-quiet quasar PDS 456 are presented .
The X–ray spectrum is characterized by a prominent ionized edge at 8–9 keV ( originally discovered by RXTE , Reeves et al .
2000 ) and by a soft excess below 1.5 keV .
The lack of any significant iron K \alpha emission line suggests for the edge an origin from line–of–sight material rather than from reflection from a highly ionized accretion disc .
The hard X–ray continuum is indeed well modelled by transmission through a highly-ionized medium with a large column density ( N _ { Hwarm } \sim 4.5 \times 10 ^ { 24 } cm ^ { -2 } ) plus an additional cold absorber with a lower column density ( N _ { Hcold } \sim 2.7 \times 10 ^ { 22 } cm ^ { -2 } ) .