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Astron. Astrophys. 325, L17-L20

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Letter to the Editor

BeppoSAX observation of 3C273: broadband spectrum
and detection of a low-energy absorption feature

P. Grandi1, M. Guainazzi2,1, T. Mineo3, A.N. Parmar4, F. Fiore2,5, A. Matteuzzi2, F. Nicastro1, G.C. Perola6, L. Piro1, M. Cappi7,8, G. Cusumano3, F. Frontera9 S. Giarrusso3, E. Palazzi5, and S. Piraino3

1Istituto di Astrofisica Spaziale, C.N.R., Via Enrico Fermi, 21 I-00044 Frascati (RM), Italy
2BeppoSAX Science Data Center , c/o Nuova Telespazio, Via Corcolle 19 I-00131 Roma, Italy
3Istituto di Fisica Cosmica ed Applicazioni dell'Informatica C.N.R., Via Ugo La Malfa 153, I-90146, Palermo, Italy
4Astrophysics Division, Space Science Department of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
5Osservatorio Astronomico di Roma, Via dell'Osservatorio, I-00044, Monteporzio Catone, Italy
6Dipartimento di Fisica "E.Amaldi", Università degli Studi "Roma 3", Via della Vasca Navale 84, I-00146, Roma, Italy
7Istituto di Tecnologie e Studio delle radiazioni Extraterrestri C.N.R., Via P.Gobetti 101, I-40129, Bologna, Italy
8The Institute of Physical and Chemical Research (RIKEN), Wako-shi, Saitama, 350-01, Japan
9Dipartimento di Fisica, Università di Ferrara, Via Paradiso 11, I-44100 Ferrara, Italy

Received 3 June 1997 / Accepted 26 June 1997


We report the results of a 3C273 observation performed during the Science Verification Phase (SVP) of the BeppoSAX satellite. The broad-band spectrum is well represented by a power-law between ~ 1 keV and 200 keV. The spectral slope is flat ( FORMULA ), with a weak emission line at FORMULA keV (rest frame) of EW FORMULA eV. Below 1 keV, a deviation from a power-law due to an absorption feature plus a soft component is present. This is the first time that a feature in absorption at FORMULA keV (observer frame) is unambiguously detected in 3C273.

Key words: X-ray: observations - Quasar: 3C273

Send offprint requests to: P. Grandi

© European Southern Observatory (ESO) 1997

Online publication: September 9, 1997
Last change: April 28, 1998