Highly ionized iron absorption lines from outflowing gas in the X-ray spectrum of NGC 1365

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 sigma for the strongest to similar to 4 sigma 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 sigma for each line), in two previous shorter (similar to 10 ks) XMM- Newton observations. The spectral analysis identifies these features as Fe xxv and Fe xxvi K alpha and K beta lines, outflowing with velocities varying between similar to 1000 and similar to 5000 km s (-1) among the observations. These are the highest quality detections of such lines so far. The high equivalent widths [EW(K alpha) similar to 100eV] and the K alpha/ K beta ratios imply that the lines are due to absorption of the AGN continuum by a highly ionized gas with column density N-H similar to 5 x 10(23)cm (-2) at a distance of similar to( 50 - 100) R-S from the continuum source.