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Astron. Astrophys. 325, L13-L16 (1997)

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Letter to the Editor

Hard X-ray detection of NGC 1068 with BeppoSAX

G. Matt 1, M. Guainazzi 2, F. Frontera 3, L. Bassani 3, W.N. Brandt 4, A.C. Fabian 5, F. Fiore 2, 6, F. Haardt 7, K. Iwasawa 5, R. Maiolino 8, G. Malaguti 3, A. Marconi 9, 10, A. Matteuzzi 2, S. Molendi 11, G.C. Perola 1, S. Piraino 12 and L. Piro 13

1 Dipartimento di Fisica "E. Amaldi", Università degli Studi "Roma Tre", Via della Vasca Navale 84, I-00146 Roma, Italy
2 SAX/SDC Nuova Telespazio, Via Corcolle 19, I-00131 Roma, Italy
3 Istituto Tecnologie e Studio Radiazioni Extraterrestri, CNR, Via Gobetti 101, I-40129 Bologna, Italy
4 Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
5 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, U.K.
6 Osservatorio Astronomico di Roma, Via dell'Osservatorio, I-00044 Monteporzio-Catone, Italy
7 Dipartimento di Fisica, Università di Milano, Via Celoria 16, I-20133 Milano, Italy
8 MPI für Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei München, Germany
9 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, U.S.A.
10 Dipartimento di Astronomia e Scienza dello Spazio, Largo E. Fermi 5, I-50125 Firenze, Italy
11 Istituto di Fisica Cosmica e Tecnologie Relative, Via Bassini 15, I-20133 Milano, Italy
12 Istituto di Fisica Cosmica ed Applicazioni dell'Informatica, Via Ugo La Malfa 153, I-90146 Palermo, Italy
13 Istituto di Astrofisica Spaziale - C.N.R., Via E. Fermi 21, I-00044 Frascati, Italy

Received 21 April 1997 / Accepted 13 June 1997


We report on the first detection above [FORMULA] 10 keV of the archetypal Compton-thick Seyfert 2 galaxy NGC 1068. This detection, obtained with the PDS instrument onboard BeppoSAX in the 20-100 keV range, confirms the hardness of the X-ray spectrum above a few keV (as indicated by ASCA observations) and supports models envisaging a mixture of both neutral and ionized reflections of an otherwise invisible nuclear continuum, the neutral reflection component being the dominant one in hard X-rays.

Key words: X-rays: galaxies – Galaxies: Seyfert – Galaxies: individual: NGC1068

Send offprint requests to: G. Matt (matt@amaldi.fis.uniroma3.it)

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© European Southern Observatory (ESO) 1997

Online publication: April 28, 1998