X-ray reverberation in NLS1
  Reverberation from scattering material around the black hole in active
galactic nuclei is expected to produce a characteristic signature in a Fourier
analysis of the time delays between directly-viewed continuum emission and the
scattered light. Narrow-line Seyfert 1 galaxies (NLS1) are highly variable at
X-ray energies, and are ideal candidates for the detection of X-ray
reverberation. We show new analysis of a small sample of NLS1 that clearly
shows the expected time-delay signature, providing strong evidence for the
existence of a high covering fraction of scattering and absorbing material a
few tens to hundreds of gravitational radii from the black hole. We also show
that an alternative interpretation of time delays in the NLS1 1H0707-495, as
arising about one gravitational radius from the black hole, is strongly
disfavoured in an analysis of the energy-dependence of the time delays.
