The soft X-ray absorption lines of the Seyfert 1 galaxy MCG-6-30-15

• Published in: Monthly notices of the Royal Astronomical Society 2004-09, Vol.353 (1), p.319-328
• Main Authors: Turner, A. K., Fabian, A. C., Lee, J. C., Vaughan, S.
• Format: Article
• Language: English
• Subjects: galaxies: active; galaxies: general; galaxies: individual: MCG-6-30-15; galaxies: Seyfert; X-rays: galaxies
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2004.08075.x

ABSTRACT The absorption lines in the soft X‐ray spectrum of  MCG–6‐30‐15 are studied using the reflection grating spectrometer data from the 2001 XMM–Newton 320‐ks observation. A line search of the full time‐averaged spectrum reveals 51 absorption lines and one emission line. The equivalent widths of the lines are measured and the majority of the lines identified. We find lines produced by a broad range of charge states for several elements, including almost all the charge states of oxygen and iron, suggesting a broad range of ionization parameters is present in the warm absorber. The equivalent widths of the lines are broadly consistent with the best‐fitting warm absorber models from Turner et al. The equivalent widths of the absorption lines allow confidence limits on the column density of the species to be determined. For O vii, a column density of 1018.36–1018.86 cm−2 is found. This column density of O vii, when combined with the inferred Fe i absorption, is sufficient to explain the drop in flux at 0.7 keV as being due to absorption from the warm absorber. Fitting O i K‐edge absorption to the spectrum reveals a column of 1017.51–1017.67 cm−2 of O i, suggesting an Fe:O ratio of ∼1:2, consistent with the neutral iron being in the form of iron oxide dust. Variability is seen in a few absorption lines, but the majority of the absorption features, including the prominent absorption edges, stay constant throughout the observation despite variability in the continuum flux.