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Issue
A&A
Volume 401, Number 3, April III 2003
Page(s) 903 - 910
Section Galactic structure and dynamics
DOI http://dx.doi.org/10.1051/0004-6361:20030160


A&A 401, 903-910 (2003)
DOI: 10.1051/0004-6361:20030160

The history of the iron K $_{\alpha}$ line profile in the Piccinotti AGN ESO 198-G24

M. Guainazzi

XMM-Newton Science Operation Center, VILSPA, ESA, Apartado 50727, 28080 Madrid, Spain
(Received 26 August 2002 / Accepted 30 January 2003 )

Abstract
This paper presents ASCA (July 1997), XMM-Newton (December 2000) and BeppoSAX (January 2001) observations of the Piccinotti Seyfert 1 galaxy ESO 198-G24. The BeppoSAX 0.1-200 keV spectrum exhibits reprocessing features, probably produced by an X-ray illuminated, relativistic accretion disk subtending a solid angle $\la$ $2 \pi$. During the XMM-Newton observation the fluorescent iron K $_{\alpha}$ line profile (centroid energy $E_{\rm c} \simeq 6.4$ keV) was broad and twice as bright as in the BeppoSAX observation. An additional emission feature ( $E_{\rm c} \simeq 5.7$ keV), detected at the 96.3% confidence level, may be part of a relativistic, double-peaked profile. By contrast, in the earlier ASCA observation the line profile is dominated by a remarkably narrow "core" (intrinsic width, $\sigma < 50$ eV). If this component is produced by reflection off the inner surface of a molecular torus, its large Equivalent Width ( $\simeq$ 300 eV) most likely represents the "echo" of a previously brighter flux state, in agreement with the dynamical range covered by the historical X-ray light curve in ESO 198-G24.


Key words: accretion, accretion discs -- galaxies: active -- galaxies: individual: ESO 198-G24 -- X-rays: galaxies -- galaxies -- nuclei

Offprint request: M. Guainazzi, mguainaz@xmm.vilspa.esa.es

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