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Astron. Astrophys. 349, L57-L60 (1999)

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Letter to the Editor

BeppoSAX unveils the nuclear component in NGC 6240

P. Vignati 1, S. Molendi 1, G. Matt 2, M. Guainazzi 3, L.A. Antonelli 4, L. Bassani 5, W.N. Brandt 6, A.C. Fabian 7, K. Iwasawa 7, R. Maiolino 8, G. Malaguti 5, A. Marconi 8 and G.C. Perola 2

1 Istituto di Fisica Cosmica "G.Occhialini", Via Bassini 15, I-20133 Milano, Italy
2 Dipartimento di Fisica "E. Amaldi", Università degli Studi Roma Tre, Via della Vasca Navale 84, I-00146 Roma, Italy
3 Astrophysics Division, Space Science Department of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
4 Osservatorio Astronomico di Roma, Via dell'Osservatorio, I-00044 Monteporzio-Catone, Italy
5 Istituto Tecnologie e Studio Radiazioni Extraterrestri, CNR, Via Gobetti 101, I-40129 Bologna, Italy
6 Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA
7 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
8 Osservatorio Astrofisico di Arcetri, L. E.Fermi 5, I-50125 Firenze, Italy

Received 29 July 1999 / Accepted 23 August 1999


The direct nuclear X-ray emission of the ultraluminous IRAS galaxy NGC 6240 has been observed by Beppo SAX. It is seen through an absorber with [FORMULA] cm-2. The 2-10 keV X-ray luminosity of [FORMULA] erg s-1 definitely proves that a powerful AGN is hosted in this galaxy, despite the LINER optical appearance. Assuming the typical [FORMULA] ratio for quasars, our result implies that it is the AGN and not the starburst that dominates the energy output of NGC 6240.

Key words: X-rays: galaxies – galaxies: Seyfert – galaxies: individual: NGC 6240

© European Southern Observatory (ESO) 1999

Online publication: September 2, 1999