1H0419-577: A "two-state" soft X-ray Seyfert galaxy

M. Guainazzi, A. Comastri, G. M. Stirpe, W. N. Brandt, F. Fiore, K. M. Leighly, G. Matt, S. Molendi, E. M. Puchnarewicz, L. Piro, A. Siemiginowska

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


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 (Γ ∼ 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 An analysis of a still unpublished ROSAT observation of the same target reveals that the soft X-ray spectrum has undergone a transition from a steep (Γ = 2.5) to a flat (Γ = 1.55) state, at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.

Original languageEnglish (US)
Pages (from-to)327-336
Number of pages10
JournalAstronomy and Astrophysics
Issue number2
StatePublished - Nov 10 1998

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of '1H0419-577: A "two-state" soft X-ray Seyfert galaxy'. Together they form a unique fingerprint.

Cite this