Bibcode
Mezcua, M.; Prieto, M. A.; Fernández-Ontiveros, J. A.; Tristram, K. R. W.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society: Letters, Volume 457, Issue 1, p.L94-L98
Fecha de publicación:
3
2016
Número de citas
13
Número de citas referidas
13
Descripción
In some AGN, nuclear dust lanes connected to kpc-scale dust structures
provide all the extinction required to obscure the nucleus, challenging
the role of the dusty torus proposed by the Unified Model. In this
letter, we show the pc-scale dust and ionized gas maps of Circinus
constructed using sub-arcsec-accuracy registration of infrared VLT AO
images with optical Hubble Space Telescope images. We find that the
collimation of the ionized gas does not require a torus but is caused by
the distribution of dust lanes of the host galaxy on ˜10 pc
scales. This finding questions the presumed torus morphology and its
role at parsec scales, as one of its main attributes is to collimate the
nuclear radiation, and is in line with interferometric observations
which show that most of the pc-scale dust is in the polar direction. We
estimate that the nuclear dust lane in Circinus provides 1/3 of the
extinction required to obscure the nucleus. This constitutes a
conservative lower limit to the obscuration at the central parsecs,
where the dust filaments might get optically thicker if they are the
channels that transport material from ˜100 pc scales to the
centre.