Nuclear obscuration in active galactic nuclei
  The material surrounding accreting supermassive black holes connects the
active galactic nucleus (AGN) with its host galaxy and, besides being
responsible for feeding the black hole, provides important information on the
feedback that nuclear activity produces on the galaxy. In this review we
summarize our current understanding of the close environment of accreting
supermassive black holes obtained from studies of local AGN carried out in the
infrared and X-ray band. The structure of this circumnuclear material is
complex, clumpy and dynamical, and its covering factor depends on the accretion
properties of the AGN. From the infrared point of view, this obscuring material
is a transition zone between the broad- and narrow-line region, and at least in
some galaxies, it consists of two structures: an equatorial disk/torus and a
polar component. In the X-ray regime, the obscuration is produced by multiple
absorbers on various spatial scales, mostly associated with the torus and the
broad-line region. In the next decade the new generation of infrared and X-ray
facilities will greatly contribute to our understanding of the structure and
physical properties of nuclear obscuration in AGN.
