The formation of stellar nuclear discs in bar-induced gas inflows
  The role of gas in the mass assembly at the nuclei of galaxies is still
subject to some uncertainty. Stellar nuclear discs bridge the gap between the
large-scale galaxy and the central massive objects that reside there. Using a
high resolution simulation of a galaxy forming out of gas cooling and settling
into a disc, we study the formation and properties of nuclear discs. Gas,
driven to the centre by a bar, settles into a rotating star-forming nuclear
disc (ND). This ND is thinner, younger, kinematically cooler, and more
metal-rich than the surrounding bar. The ND is elliptical and orthogonal to the
bar. The complex kinematics in the region of the ND are a result of the
superposition of older stars streaming along the bar and younger stars
circulating within the ND. The signature of the ND is therefore subtle in the
kinematics. Instead the ND stands out clearly in metallicity and age maps. We
compare the model to the density and kinematics of real galaxies with NDs
finding qualitative similarities. Our results suggest that gas dissipation is
very important for forming nuclear structures.
