Bibcode
DOI
Prieto, M. Almudena; Maciejewski, Witold; Reunanen, Juha
Bibliographical reference
The Astronomical Journal, Volume 130, Issue 4, pp. 1472-1481.
Advertised on:
10
2005
Citations
79
Refereed citations
67
Description
Near-IR images of the prototype LINER/Seyfert type 1 galaxy NGC 1097
observed with the Very Large Telescope using adaptive optics disclose
with unprecedented detail a complex central network of filamentary
structure spiraling down to the center of the galaxy. The structure,
consisting of several spiral arms, some almost completing a revolution
about the center, is most prominent within a radius of about 300 pc. Gas
and dust may be channelled to the center of NGC 1097 along this central
spiral. Some filaments can be traced farther out, where they seem to
connect with the nuclear star-forming ring at a 0.7 kpc radius. Straight
principal shocks running along the primary large-scale bar of NGC 1097,
seen in the optical images as prominent dust lanes, curve into this
ring, but radio polarization vectors cross the nuclear ring at a rather
large angle. Here we attempt to explain this morphology in terms of
three-dimensional gas flow in a barred galaxy. In our scenario, parts of
the principal shock that propagate in the off-plane gas can cross the
nuclear star-forming ring and excite waves inward from it. If the
dispersion relation of the excited waves allows for their propagation,
they will naturally take the shape of the observed central spiral. The
nuclear region of NGC 1097 remains unresolved at subarcsecond scales in
the near-IR, with an upper size limit of <10 pc FWHM. Thus, any
putative central dusty torus or gaseous disk envisaged by the active
galactic nucleus (AGN) unified schemes has to be smaller than 10 pc in
diameter at near-IR wavelengths. The extinction in the region between
the nuclear star-forming ring and the nucleus increases very moderately,
reaching Av~1 at the immediate surroundings of the nucleus.
Thus, if the nuclear filaments are tracing cold dust, they contribute to
a very low extinction in the line of sight and are likely to be
distributed in a rather thin disk.