2005ApJ...630L.129R

We present the discovery of four absorption lines in the X-ray spectrum of the Seyfert galaxy NGC 1365, at energies between 6.7 and 8.3 keV. The lines are detected with high statistical confidence (from >20 σ for the strongest to ∼4 σ for the weakest) in two XMM-Newton observations 60 ks long. We also detect the same lines, with a lower signal-to-noise ratio (but still >2 σ for each line), in two previous shorter (∼10 ks) XMM-Newton observations. The spectral analysis identifies these features as Fe XXV and Fe XXVI Kα and Kβ lines, outflowing with velocities varying between ∼1000 and ∼5000 km/s among the observations. These are the highest quality detections of such lines so far. The high equivalent widths [EW(Kα)∼100 eV] and the Kα/Kβ ratios imply that the lines are due to absorption of the AGN continuum by a highly ionized gas with column density N_H∼5x10²³/cm2 at a distance of ~(50-100)R_S from the continuum source.