The link between broad emission line fluctuations and non-thermal
  emission from the inner AGN jet
  AGN reverberate when the broad emission lines respond to changes of the
ionizing thermal continuum emission. Reverberation measurements have been
commonly used to estimate the size of the broad-line region (BLR) and the mass
of the central black hole. However, reverberation mapping studies have been
mostly performed on radio-quiet sources where the contribution of the jet can
be neglected. In radio-loud AGN, jets and outflows may affect substantially the
relation observed between the ionizing continuum and the line emission. To
investigate this relation, we have conducted a series of multiwavelength
studies of radio-loud AGN, combining optical spectral line monitoring with
regular VLBI observations. Our results suggest that at least a fraction of the
broad-line emitting material can be located in a sub-relativistic outflow
ionized by non-thermal continuum emission generated in the jet at large
distances (> 1pc) from the central engine of AGN. This finding may have a
strong impact on black hole mass estimates based on measured widths of the
broad emission lines and on the gamma-ray emission mechanisms.
