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In some radio-quiet active galaxies (AGN), high-energy absorption features inthe x-ray spectra have been interpreted as Ultrafast Outflows (UFOs) -- highlyionised material (e.g. Fe XXV and Fe XXVI) ejected at mildly relativisticvelocities. In some cases, these outflows can carry energy in excess of thebinding energy of the host galaxy. Needless to say, these features demand ourattention as they are strong signatures of AGN feedback and will influencegalaxy evolution. For the same reason, alternative models need to be discussedand refuted or confirmed. Gallo & Fabian proposed that some of these featurescould arise from resonance absorption of the reflected spectrum in a layer ofionised material located above and corotating with the accretion disc.Therefore, the absorbing medium would be subjected to similar blurring effectsas seen in the disc. A priori, the existence of such plasma above the disc isas plausible as a fast wind. In this work, we highlight the ambiguity bydemonstrating that the absorption model can describe the ~7.6 keV absorptionfeature (and possibly other features) in the quasar PG 1211+143, an AGN that isoften described as a classic example of an UFO. In this model, the 2-10 keVspectrum would be largely reflection dominated (as opposed to power lawdominated in the wind models) and the resonance absorption would be originatingin a layer between about 6 and 60 gravitational radii. The studies of suchfeatures constitutes a cornerstone for future X-ray observatories like Astro-Hand Athena+. Should our model prove correct, or at least important in somecases, then absorption will provide another diagnostic tool with which to probethe inner accretion flow with future missions.

The origin of blue-shifted absorption features in the X-ray spectrum of PG 1211+143: Outflow or disc?