Ionization structure of the warm wind in NGC 5548
  We present the results from our 140 ks XMM-Newton and 500 ks Chandra observation of NGC 5548. The velocity structure of the X-ray absorber is consistent with the velocity structure measured in the simultaneous UV spectra. In the X-rays we can separate the highest outflow velocity component, -1040 km/s, from the other velocity components. This velocity component spans at least three orders of magnitude in ionization parameter, producing both highly ionized X-ray absorption lines (Mg XII, Si XIV) and UV absorption lines. A similar conclusion is very probable for the other four velocity components. We show that the lower ionized absorbers are not in pressure equilibrium with the rest of the absorbers. Instead, a model with a continuous distribution of column density versus ionization parameter gives an excellent fit to our data. 
K. C. Steenbrugge, J. S. Kaastra, D. M. Crenshaw, S. B. Kraemer, N.   Arav, I. M. George, D. A. Liedahl, F. B. S. Paerels, T...