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Astron. Astrophys. 362, 69-74 (2000)

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On the peculiar X-ray properties of the bright nearby radio-quiet quasar PDS 456

C. Vignali 1,2, A. Comastri 2, F. Nicastro 3,4, G. Matt 5, F. Fiore 3,4,6 and G.G.C. Palumbo 1

1 Dipartimento di Astronomia, Università di Bologna, Via Ranzani 1, 40127 Bologna, Italy (vignali@kennet.bo.astro.it)
2 Osservatorio Astronomico di Bologna, Via Ranzani 1, 40127 Bologna, Italy
3 Harvard-Smithsonian Center of Astrophysics, 60 Garden Street, Cambridge MA 02138, USA
4 Osservatorio Astronomico di Roma, Via Frascati 33, 00044 Monteporzio, Italy
5 Dipartimento di Fisica, Università degli Studi "Roma Tre", Via della Vasca Navale 84, 00146 Roma, Italy
6 BeppoSAX Science Data Center, Via Corcolle 19, 00131 Roma, Italy

Received 14 March 2000 / Accepted 21 August 2000


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[FORMULA] 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 ([FORMULA] [FORMULA] 4.5 [FORMULA] 1024 cm-2) plus an additional cold absorber with a lower column density ([FORMULA] [FORMULA] 2.7 [FORMULA] 1022 cm-2).

Key words: galaxies: nuclei – galaxies: quasars: individual: PDS 456 – X-rays: galaxies

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© European Southern Observatory (ESO) 2000

Online publication: October 30, 19100