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The effect of radial migration on galactic disk heating : implications to thick disk formation

Ivan Minchev (Astrophysical Institute, Potsdam)

Disc non-axisymmetrc components, such as spirals and central bars, are presently known to play a major role in shaping galactic discs. An important aspect of disks’ secular evolution has been shown to be the radial migration of stars, inevitably resulting from these perturbers.
It has been suggested recently that migration can bring out stars from the inner disk with high vertical energies, thus populating a thick disk component. Analyzing N-body simulations, I will show that, contrary to expectation, as stellar samples migrate, on the average, their energy and velocity dispersion change in such a way as to match the non-migrating population at the radius at which they arrive. An increase of the velocity dispersions from migrators is found mostly beyond two disk scale-lengths and it is on the order of 5-10% (likely less if gas inflow is considered), giving rise to disc flaring. I will show that a large portion of the inner disk is, in fact, cooled by migrators.