EDP Sciences
Free access
Volume 365, Number 3, January III 2001
Page(s) 400 - 408
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20000152

A&A 365, 400-408 (2001)
DOI: 10.1051/0004-6361:20000152

BeppoSAX observations of Narrow-Line Seyfert 1 galaxies

II. Ionized iron features in Arakelian 564
A. Comastri1, G. M. Stirpe1, C. Vignali1, 2, W. N. Brandt3, K. M. Leighly4, F. Fiore5, 6, 7, M. Guainazzi8, G. Matt9, F. Nicastro7, E. M. Puchnarewicz10 and A. Siemiginowska7

1  Osservatorio Astronomico di Bologna, Via Ranzani 1, 40127 Bologna, Italy
2  Dipartimento di Astronomia, Università di Bologna, Via Ranzani 1, 40127 Bologna, Italy
3  Dept. of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA
4  Department of Astronomy, Columbia University, 538 West 120th Street, New York, NY 10027, USA
5  Osservatorio Astronomico di Roma, Via Frascati 33, 00044 Monteporzio-Catone, Italy
6  SAX-Science Data Center, Nuova Telespazio, Via Corcolle 19, 00131 Roma, Italy
7  Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
8  XMM-Newton SOC, VILSPA - ESA, Apartado 50727, 28080 Madrid, Spain
9  Dipartimento di Fisica "E. Amaldi", Università degli Studi "Roma Tre", Via della Vasca Navale 84, 00146 Roma, Italy
10  Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK

(Received 21 July 2000 / Accepted 23 October 2000)

The BeppoSAX observations of the bright Narrow-Line Seyfert 1 galaxy Ark 564 are presented along with a high quality optical spectrum taken at the 1.5 m telescope at La Silla. The 0.1-10 keV X-ray spectrum is characterized by a strong soft component which is best described by blackbody-like emission with a temperature of $\sim$160 eV. At higher energies a steep ( $\Gamma \simeq$ 2.4) power-law tail is present. There is evidence of an ionized reflector in the form of an iron line and edge. We do not find significant evidence of soft X-ray features if the spectrum is modelled with a two component continuum. The optical and X-ray spectral properties support the hypothesis of a high accretion rate onto a low mass black hole.

Key words: X -- rays: galaxies -- galaxies: Seyfert -- galaxies: individual: Ark 564

Offprint request: A. Comastri, comastri@bo.astro.it

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© ESO 2001