Reverberation mapping and the disk-wind model of the broad-line region

Using the disk-wind model of Murray et al., we calculate line profiles and frequency-resolved response functions for broad-line emission from the surface of an accretion disk in an active galactic nucleus in the presence of a radiatively driven wind. We find that the combined effects of the shears in the wind and in the disk itself produce anisotropic line emission, which solves several well-known problems connected with disk models of the broad-line region. In particular, the broadening of resonance lines such as C IV, Ly alpha, and N V can be attributed to orbital motion of the disk gas at radii as close as similar to 10(16) cm in Seyferts, without requiring unrealistically large emission regions in order to produce single-peaked profiles. Furthermore, the anisotropy of the line emission results in frequency-dependent response functions which are no longer red-blue symmetric, so that the time delays inferred for the various red and blue components of the line agree qualitatively with recent reverberation mapping observations of NGC 5548.