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

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

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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 (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 An analysis of a still unpublished ROSAT observation of the same target reveals that the soft X-ray spectrum has undergone a transition from a steep (Γ = 2.5) to a flat (Γ = 1.55) state, at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
Volume339
Issue number2
StatePublished - Nov 10 1998

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Seyfert galaxies
x rays
optical spectrum
power law
radio
continuums
iron

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Guainazzi, M., Comastri, A., Stirpe, G. M., Brandt, W. N., Fiore, F., Leighly, K. M., ... Siemiginowska, A. (1998). 1H0419-577: A "two-state" soft X-ray Seyfert galaxy. Astronomy and Astrophysics, 339(2), 327-336.
Guainazzi, M. ; Comastri, A. ; Stirpe, G. M. ; Brandt, William Nielsen ; Fiore, F. ; Leighly, K. M. ; Matt, G. ; Molendi, S. ; Puchnarewicz, E. M. ; Piro, L. ; Siemiginowska, A. / 1H0419-577 : A "two-state" soft X-ray Seyfert galaxy. In: Astronomy and Astrophysics. 1998 ; Vol. 339, No. 2. pp. 327-336.
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Guainazzi, M, Comastri, A, Stirpe, GM, Brandt, WN, Fiore, F, Leighly, KM, Matt, G, Molendi, S, Puchnarewicz, EM, Piro, L & Siemiginowska, A 1998, '1H0419-577: A "two-state" soft X-ray Seyfert galaxy', Astronomy and Astrophysics, vol. 339, no. 2, pp. 327-336.

1H0419-577 : A "two-state" soft X-ray Seyfert galaxy. / Guainazzi, M.; Comastri, A.; Stirpe, G. M.; Brandt, William Nielsen; Fiore, F.; Leighly, K. M.; Matt, G.; Molendi, S.; Puchnarewicz, E. M.; Piro, L.; Siemiginowska, A.

In: Astronomy and Astrophysics, Vol. 339, No. 2, 10.11.1998, p. 327-336.

Research output: Contribution to journalArticle

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AU - Guainazzi, M.

AU - Comastri, A.

AU - Stirpe, G. M.

AU - Brandt, William Nielsen

AU - Fiore, F.

AU - Leighly, K. M.

AU - Matt, G.

AU - Molendi, S.

AU - Puchnarewicz, E. M.

AU - Piro, L.

AU - Siemiginowska, A.

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Guainazzi M, Comastri A, Stirpe GM, Brandt WN, Fiore F, Leighly KM et al. 1H0419-577: A "two-state" soft X-ray Seyfert galaxy. Astronomy and Astrophysics. 1998 Nov 10;339(2):327-336.