Institut für Astronomie und Astrophysik

Abteilung Astronomie

Preprint 08a/95

ROSAT observations of radio-loud AGN

Fabian Rother(1), Hermann Brunner(2), Michael Maisack(1), Rüdiger Staubert(1)

(1)Institut für Astronomie und Astrophysik, Astronomie, Universität Tübingen, D-72076 Tübingen, Germany
(2)Astrophysikalisches Institut Potsdam, D-14482 Potsdam, Germany

Poster presented at the Conference Röntgenstrahlung from the Universe, Würzburg, Germany, September 25-29, 1995
to be published in the Proceedings of this Conference

Abstract. We have analysed the ROSAT soft X-ray spectra of a sample of radio loud AGN from the public archive. Based on the catalogues of Véron-Cetty & Véron (1993), Hewitt & Burbidge (1993), Stickel et al. (1994) and the NED database the sample was selected by the following criteria:

• radio loudness (alpha_ro > 0.4),
• radio flux S_5GHz > 0.5 Jy,
• position within 55' of the center of FOV in pointed ROSAT PSPC observations.

Our sample comprises 165 detected radio loud AGN (including 6 AGN without known redshift). It contains 98 FSQ (radio flat spectrum quasars with alpha_r < 0.5), 35 SSQ (radio steep spectrum quasars with alpha_r > 0.5) and 32 BL Lac objects.
We find that the FSQ have flatter spectra than the SSQ and BL Lacs in the ROSAT energy range (0.1 - 2.4 keV). No difference between these classes is found in alpha_ro and alpha_ox. The ROSAT spectra of radio loud and radio quiet quasars are steeper than the spectra measured at higher energies (> 1 keV) by EINSTEIN, EXOSAT or GINGA.

Paper (37k gzip'ed Postscript including figures)

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Jürgen Barnstedt (barnstedt AT astro.uni-tuebingen.de) Last updated 04-Aug-1997