Digging process in NGC 6951: the molecular disc bumped by the jet
  We present a study of the central 200 pc of the galaxy NGC 6951, SAB(rs)bc,
an active twin of the Milky Way, at a distance of 24 Mpc. Its nucleus has been
observed in the optical with the GMOS-IFU, showing an outflow, and with the
HST/ACS, revealing two extended structures with similar orientation, suggesting
the presence of a collimating and/or obscuring structure. In order to ascertain
this hypothesis, adaptive optics assisted NIR integral field spectroscopic
observations were obtained with the NIFS spectrograph in the Gemini North
telescope. We detected a compact structure of H$_2$ molecular gas, interpreted
as a nearly edge-on disc with diameter of $\sim$47 pc, PA=124$\deg$ and
velocity range from -40 to +40 km s$^{-1}$. This disc is misaligned by 32$\deg$
with respect to the radio jet and the ionization cones seen in the optical.
There are two regions of turbulent gas, with position angles similar to the
jet/cones, seen both in molecular and ionized phases; these regions are
connected to the edges of the molecular disc and coincide with a high ratio of
[N II]/H$\alpha$=5, suggesting that these regions are shock excited, partially
ionized or both. We explain these structures as a consequence of a "digging
process" that the jet inflicts on the disc, ejecting the molecular gas towards
the ionization cones. The dynamical mass within 17 pc is estimated as
$6.3\times10^{6}$$M_{\odot}$. This is an interesting case of an object
presenting evidence of a connected feeding-feedback structure.
