Transient, Co-rotating Spiral Arms and Chemo-Dynamics of the Galactic Disk
Dr Daisuke Kawata
University College London, UK
Spiral density wave theory attempts to describe the spiral pattern in spiral galaxies in terms of a long-lived wave structure with a constant pattern speed in order to avoid the winding dilemma. The pattern is consequently a rigidly rotating, long-lived feature. We run N-body/SPH chemodynamical simulations of a Milky Way sized barred galaxy and find that the spiral arms are transient features whose pattern speeds decrease with radius, in such a way that the pattern speed is almost equal to the the rotation curve of the galaxy. We trace particle motion around the spiral arms and demonstrate that such co-rotating spiral arms induce efficient radial migration of the stellar component at all radii in the disc. We show that particles join the arm from both the leading and trailing side. Particles move along the arm in the radial direction and we find a clear trend that they migrate toward the outer (inner) radii on the trailing (leading) side of the arm. Our simulations demonstrate that because of the co-rotating spiral arm the particles continue to be accelerated (decelerated) by the spiral arm for long periods, which leads to strong and efficient migration.
Date: Vendredi, le 26 août 2011 Heure: 12:00 Lieu: Université Laval Pavillon Alexandre-Vachon, local 1661