Open AccessA longer XMM–Newton look at I Zwicky 1: physical conditions and variability of the ionized absorbers
Author(s) -
Costantini E.,
Gallo L. C.,
Brandt W. N.,
Fabian A. C.,
Boller Th.
Publication year - 2007
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2007.11646.x
Subject(s) - physics , ionization , astrophysics , galaxy , spectral line , luminosity , line of sight , line (geometry) , outflow , flux (metallurgy) , plasma , astronomy , ion , geometry , mathematics , materials science , quantum mechanics , meteorology , metallurgy
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 ( N H ∼ 10 21 cm −2 ) and ionization parameters log ξ∼ 0 and 2.5. Comparing this observation with a 2002 XMM–Newton data set, we see a clear anticorrelation between the X‐ray ionization parameter ξ X 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.