1H0419-577: a ``two-state'' soft X-ray Seyfert galaxy
Abstract
In this paper we report on the first simultaneous optical and X-ray (Beppo-SAX) observations of the radio-quiet AGN 1H0419-577. The optical spectrum clearly leads us to classify this source as a Seyfert 1. The X-ray spectrum is, however, somewhat at odds with this classification: a simple flat (Gamma ~ 1.55) and featureless power-law is a good description of the whole 1.8-40 keV spectrum, even if the upper limit to a broad iron line is not very tight. An analysis of a still unpublished ROSAT observation of the same target reveals that the soft X-ray spectrum has undergone a transition from a steep (Gamma = 2.5) to a flat (Gamma = 1.55) state, at least in the 0.7-2 keV band. If this difference is due to a remarkably variable soft excess, it is unlikely that a single component is responsible for the optical/UV/soft X-ray spectral distribution. The hypothesis that the difference is due to a change in the primary X-ray continuum and its implications for current Comptonization models are discussed. Partly based on observations collected at the European Southern Observatory, La Silla, Chile
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 1998
- DOI:
- 10.48550/arXiv.astro-ph/9808009
- arXiv:
- arXiv:astro-ph/9808009
- Bibcode:
- 1998A&A...339..327G
- Keywords:
-
- X-RAYS: GALAXIES;
- GALAXIES: SEYFERT;
- GALAXIES: INDIVIDUAL: 1H0419-577;
- Astrophysics
- E-Print:
- 11 pages, Latex, 8 Postscript figures, accepted for publication in Astronomy and Astrophysics