A longer XMM-Newton look at i Zwicky 1: Physical conditions and variability of the ionized absorbers

E. Costantini, L. C. Gallo, W. N. Brandt, A. C. Fabian, Th Boller

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12 Scopus citations

Abstract

We present a spectral analysis of the narrow-line Seyfert 1 galaxy I Zwicky 1, focusing on the characteristics of the ionized absorbers as observed with XMM-Newton in 2005. The soft X-ray spectrum shows absorption by two components of ionized gas with a similar column density and ionization parameters and 2.5. Comparing this observation with a 2002 XMM-Newton data set, we see a clear anticorrelation between the X-ray ionization parameter and the 0.1-10 keV luminosity. Viable explanations for this effect include transient clouds or filaments crossing the line of sight in a complex geometry or a gas observed in non-equilibrium. The outflow velocity of the X-ray low-ionization absorber is consistent with the outflow of the ultraviolet (UV) absorber detected in a past Hubble Space Telescope observation. In addition, the ionic column densities of C iv and N v derived from the X-ray model are consistent with the UV values. This suggests that the low-ionization outflowing gas may survive for many years, despite large changes in flux, and that there is a tight connection between the X-ray and UV absorbers that can only be confirmed with a simultaneous UV and X-ray observation.

Original languageEnglish (US)
Pages (from-to)873-880
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Volume378
Issue number3
DOIs
StatePublished - Jul 2007

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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