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. Vignali^{1, 2}, W. N. Brandt³, K. M. Leighly⁴, F. Fiore^{5, 6, 7}, M. Guainazzi⁸, G. Matt⁹, F. Nicastro⁷, E. M. Puchnarewicz¹⁰ and A. Siemiginowska<sup>7

1</sup>  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)

Abstract
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 160 eV. At higher energies a steep ( 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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