8-12 juin, 2014


The Size of Star Clusters During Galaxy Mergers

Meghan Miholics (McMaster University)

Jeremy Webb (McMaster University), Alison Sills (McMaster University)

If a globular cluster is accreted by the Milky Way in a merger event with a dwarf galaxy it will experience a change in gravitational potential. We have performed Nbody simulations of a cluster that begins in a dwarf galaxy and is moved into the Milky Way to investigate the effect of this change on the cluster's half mass radius. We find that the cluster's half mass radius decreases rapidly in response to an increase in potential and will eventually exhibit an evolution indistinguishable from a cluster that has always lived in the Milky Way. This effect is independent of the time that the cluster is taken from the dwarf galaxy. It is also qualitatively independent of whether the cluster is placed on an orbit 6 kpc or 10 kpc from the centre of the Milky Way. However, the decrease in half mass radius is smaller and takes place over a shorter timescale when moved to a 10 kpc orbit where the difference between the potential of the dwarf galaxy and the potential of the Milky Way is smaller. If a cluster is accreted by the Milky Way in a galaxy merger with a dwarf galaxy it may not be possible to determine that the cluster was not originally from the Milky Way based on its size alone.

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