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STScI Preprint #1317
We present new BeppoSax LECS, MECS and PDS observations of five lobe-dominated, broad-line active galactic nuclei selected from the 2-Jy sample of southern radio sources. These include three radio quasars and two broad-line radio galaxies. ROSAT PSPC data, available for all the objects, are also used to better constrain the spectral shape in the soft X-ray band. The collected data cover the energy range 0.1-10 keV, reaching ~50keV for one source (Pictor A). The main result from the spectral fits is that all sources have a hard X-ray spectrum with energy index x~0.75 in the 2-10 keV range. This is at variance with the situation at lower energies where these sources exhibit steeper spectra. Spectral breaks
x~0.5 at 1-2 keV characterize in fact the overall X-ray spectra of our objects. The flat, high-energy slope is very similar to that displayed bu flat-spectrum/core-dominated quasars, which suggests that the same emission mechanism (most likely inverse Compton) produces the hard X-ray spectra in both classes. Finally, a (weak) thermal component is also present at low energies in the two broad-line radio galaxies included in our study.
1)Space Telescope Science Institute, 3700 San Martin Drive,
Baltimore MD. 21218, USA
2)Affiliated to the Astrophysics Division, Space Science
Department, European Space Agency
3)Dipartimento di Fisica, II Università di Roma
"Tor Vergata", Via della Ricerca Scientifica 1, I-00133 Roma
Italy
4)Istituto di Radioastronomia, Via Gobetti 101, I-40129 Bologna,
Italy
5)Max-Planck-Institut für Extraterrestrische Physik,
Giessenbackstrasse, D-85740 Garching bei München, Germany
6)Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125
Firenze, Italy