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 similar to 4.5 x 10(24) cm(-2)) plus an additional cold absorber with a lower column density (N-Hcold similar to 2.7 x 10(22) cm(-2)).
Vignali, C., Comastri, A., Nicastro, F., Matt, G., Fiore, F., Palumbo, G. (2000). On the peculiar X-ray properties of the bright nearby radio-quiet quasar PDS 456. ASTRONOMY & ASTROPHYSICS, 362(1), 69-74.
On the peculiar X-ray properties of the bright nearby radio-quiet quasar PDS 456
MATT, Giorgio;
2000-01-01
Abstract
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 similar to 4.5 x 10(24) cm(-2)) plus an additional cold absorber with a lower column density (N-Hcold similar to 2.7 x 10(22) cm(-2)).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.