Bibcode
Prieto, M. A.; Mezcua, M.; Fernández-Ontiveros, J. A.; Schartmann, M.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 442, Issue 3, p.2145-2164
Fecha de publicación:
8
2014
Número de citas
38
Número de citas referidas
36
Descripción
Type 2 active galactic nuclei (AGN) are by definition nuclei in which
the broad-line region and continuum light are hidden at optical/UV
wavelengths by dust. Via accurate registration of infrared (IR) Very
Large Telescope adaptive optics images with optical Hubble Space
Telescope images we unambiguously identify the precise location of the
nucleus of a sample of nearby, type 2 AGN. Dust extinction maps of the
central few kpc of these galaxies are constructed from optical-IR colour
images, which allow tracing the dust morphology at scales of few pc. In
almost all cases, the IR nucleus is shifted by several tens of pc from
the optical peak and its location is behind a dust filament, prompting
to this being a major, if not the only, cause of the nucleus
obscuration. These nuclear dust lanes have extinctions AV
≥ 3 - 6 mag, sufficient to at least hide the low-luminosity AGN
class, and in some cases are observed to connect with kpc-scale dust
structures, suggesting that these are the nuclear fueling channels. A
precise location of the ionized gas Hα and [Si VII] 2.48
μ coronal emission lines relative to those of the IR nucleus and dust
is determined. The Hα peak emission is often shifted from the
nucleus location and its sometimes conical morphology appears not to be
caused by a nuclear - torus - collimation but to be strictly defined by
the morphology of the nuclear dust lanes. Conversely, [Si VII]
2.48 μ emission, less subjected to dust extinction, reflects the
truly, rather isotropic, distribution of the ionized gas. All together,
the precise location of the dust, ionized gas and nucleus is found
compelling enough to cast doubts on the universality of the pc-scale
torus and supports its vanishing in low-luminosity AGN. Finally, we
provide the most accurate position of the NGC 1068 nucleus, located at
the south vertex of cloud B.
Proyectos relacionados
Centros de Galaxias a Escalas de Parsecs y Técnicas de Alta Resolución Espacial
Proyecto enfocado al estudio en el IR del núcleo de las galaxias más cercanas con resoluciones espaciales en el rango de 1 a 10 pc. Estas resoluciones espaciales, accesibles con los grandes telescopios de tierra usando técnicas frontera de observación, son por primera vez comparables a las que se obtienen rutinariamente con HST en el óptico y VLBI
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