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The Warm Absorber constrained by the coronal lines in Seyfert 1 galaxies
Received 6 August 1998 / Accepted 6 October 1998
We present results of the photoionization code IRIS, which calculates the spectrum emitted by the Warm Absorber (WA) in Seyfert 1 galaxies for a large grid of parameters (density, column density, ionization parameter...). We show that in Seyfert 1s, coronal lines ([Fe x], [Fe xi], [Fe xiv]...), whose emission region shares common characteristics with the WA, could be formed in the WA. Unlike the absorption edges, such as those of O vii and O viii observed in soft X-rays which are produced by the WA, these lines strongly constrain the physical parameters of the WA, especially the hydrogen density. Indeed, in order to avoid producing coronal line equivalent widths larger than observed, a high density (nH 1010 cm-3) is required for the WA in most cases. This result is obtained for the mean observed Seyfert 1 features, as well as for the case study of MCG-6-30-15. It implies that the distance of the WA from the incident radiation source is of the order of that of the Broad Line Region (BLR).
Key words: galaxies: active galaxies: individual: MCG -6-30-15 galaxies: Seyfert X-rays: galaxies
Send offprint requests to: D.Porquet
Correspondence to: Delphine.Porquet@obspm.fr
Online publication: November 26, 1998