The near-infrared broad emission line region of active galactic nuclei.
  II. The one-micron continuum
  We use quasi-simultaneous near-infrared (near-IR) and optical spectroscopy
from four observing runs to study the continuum around 1 micron in 23
well-known broad-emission line active galactic nuclei (AGN). We show that,
after correcting the optical spectra for host galaxy light, the AGN continuum
around this wavelength can be approximated by the sum of mainly two emission
components, a hot dust blackbody and an accretion disc. The accretion disc
spectrum appears to dominate the flux at ~1 micron, which allows us to derive a
relation for estimating AGN black hole masses based on the near-IR virial
product. This result also means that a near-IR reverberation programme can
determine the AGN state independent of simultaneous optical spectroscopy. On
average we derive hot dust blackbody temperatures of ~1400 K, a value close to
the sublimation temperature of silicate dust grains, and relatively low hot
dust covering factors of ~7%. Our preliminary variability studies indicate that
in most sources the hot dust emission responds to changes in the accretion disc
flux with the expected time lag, however, a few sources show a behaviour that
can be attributed to dust destruction.
