Bibcode
Coffey, D.; Longinotti, A. L.; Rodríguez-Ardila, A.; Guainazzi, M.; Miniutti, G.; Bianchi, S.; de la Calle, I.; Piconcelli, E.; Ballo, L.; Linares, M.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 443, Issue 2, p.1788-1801
Advertised on:
9
2014
Citations
8
Refereed citations
8
Description
In this work, the analysis of multi-epoch (1995-2010) X-ray observations
of the Seyfert 1 galaxy H0557-385 is presented. The wealth of data
presented in this analysis show that the source exhibits dramatic
spectral variability, from a typical unabsorbed Seyfert 1 type spectrum
to a Compton-thin absorbed state, on time-scales of ˜5 yr. This
extreme change in spectral shape can be attributed to variations in the
column density and covering fraction of a neutral absorbing medium
attenuating the emission from the central continuum source. Evidence for
Compton reflection of the intrinsic nuclear emission is present in each
of the spectra, though this feature is most prominent in the low-state
spectra, where the associated Fe emission line complex is clearly
visible. In addition to the variable absorbing medium, a warm absorber
component has been detected in each spectral state. Optical spectroscopy
concurrent with the 2010 XMM-Newton observation campaign has detected
the presence of broad optical emission lines during an X-ray absorption
event. From the analysis of both X-ray and optical spectroscopic data,
it has been inferred that the X-ray spectral variability is a result of
obscuration of the central emission region by a clumpy absorber covering
≥ 80 per cent of the source with an average column density of
NH ˜ 7 × 1023 cm-2, and
which is located outside the broad line region at a distance from the
central source consistent with the dust sublimation radius of the AGN.
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