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Astron. Astrophys. 346, 407-414 (1999)

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The complex 0.1-200 keV spectrum of the Seyfert 1 Galaxy NGC 4593

M. Guainazzi 1, G.C. Perola 2, G. Matt 2, F. Nicastro 3,2, L. Bassani 4, F. Fiore 3,5, D. DalFiume 4 and L. Piro 6

1 Astrophysics Division, Space Science Department of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
2 Dipartimento di Fisica "E.Amaldi", Università di Roma 3, Via della Vasca Navale 84, I-00146 Roma, Italy
3 Osservatorio Astronomico di Roma, Via dell'Osservatorio 5, I-00040 Monteporzio Catone, Italy
4 Istituto Tecnologie e Studio Radiazioni Extraterrestri, CNR, Via Gobetti 101, I-40129 Bologna, Italy
5 BeppoSAX Science Data Center, Via Corcolle 19, I-00131 Roma, Italy
6 Istituto di Astrofisica Spaziale, CNR, Via Fosso del Cavaliere, I-00133 Roma, Italy

Received 28 September 1998 / Accepted 17 March 1999

Abstract

We report on the first observation of the Seyfert 1 galaxy NGC 4593 in the 0.1-200 keV band, performed with the BeppoSAX observatory. Its spectral components are for the first time simultaneously measured: a power-law with photon spectral index [FORMULA] 1.9; the Compton-reflection of the primary power-law; a moderately broad ([FORMULA] eV) [FORMULA] fluorescent line from neutral iron; and an absorption edge, whose threshold energy is consistent with K-shell photoionization from OVII . The amount of reflection and the iron line properties are consistent with both being produced in a plane-parallel, X-ray illuminated relativistic accretion disc surrounding the nuclear black hole, seen at an inclination of [FORMULA]. Any cutoff of the intrinsic continuum is constrained to lay above 150 keV. The claim for a strongly variable soft excess is dismissed by our data and by a reanalysis of archival ASCA and ROSAT data.

Key words: galaxies: individual: NGC 4593 – galaxies: nuclei – galaxies: Seyfert – X-rays: galaxies

Send offprint requests to: M. Guainazzi (mguainaz@astro.estec.esa.nl)

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© European Southern Observatory (ESO) 1999

Online publication: May 21, 1999
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