Density waves in the central regions of galaxies

Abstract

Density waves in the central kpc of galaxies, taking the form of spirals, bars and/or lopsided density distributions are potential actors of the redistribution of angular momentum. They thus play an important role in the overall evolution of the central structures, not mentioning the possible link with the active/non-active nucleus. I present here kinematical evidences for the presence of such structures using new sets of observations: two-dimensional (OASIS/CFHT) and long-slit (ISAAC/VLT) spectrography of nuclear bars and spirals. I also discuss the importance of $m=1$ modes in the nuclear regions of galaxies, illustrating this with newly revealed cases and original N body simulations.