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Multi-wavelength spectroscopy of NGC 5548 revealed remarkable changes due topresence of an obscuring wind from the accretion disk. This broadened ourunderstanding of obscuration and outflows in AGN. Swift monitoring of NGC 5548shows that over the last 10 years the obscuration has gradually declined. Thisprovides a valuable opportunity for analyses that have not been feasible beforebecause of too much obscuration. The lowered obscuration, together with thehigh energy spectral coverage of Chandra HETG, facilitate the first study ofX-ray absorption lines in the obscured state. The comparison of the lines (MgXI, Mg XII, Si XIII, and Si XIV) between the new and historical spectra revealsinteresting changes, most notably the He-like absorption being significantlydiminished in 2022. Our study finds that the changes are caused by an increasein both the ionization parameter and the column density of the warm-absorberoutflow in the obscured state. This is contrary to the shielding scenario thatis evident in the appearance of the UV lines, where the inner obscuring windshields outflows that are located further out, thus lowering their ionization.The X-ray absorption lines in the HETG spectra appear to be unaffected by theobscuration. The results suggest that the shielding is complex since variouscomponents of the ionized outflow are impacted differently. We explore variouspossibilities for the variability behavior of the X-ray absorption lines andfind that the orbital motion of a clumpy ionized outflow traversing our line ofsight is the most likely explanation.

First High-Resolution Spectroscopy of X-ray Absorption Lines in the Obscured State of NGC 5548