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Paper: Galactic Disk Transformation via Massive Satellite Accretion Events
Volume: 419, Galaxy Evolution: Emerging Insights and Future Challenges
Page: 248
Authors: Purcell, C. W.; Kazantzidis, S.; Bullock, J. S.
Abstract: Accretion events involving the infall of a massive satellite galaxy (Msat ∼ 1011 Msun) onto a stellar disk in a Galactic-scale host halo (Mhost ∼ 1012 Msun) are both cosmologically common and capable of inducing significant morphological and dynamical changes in the primary system. We review the work of Purcell et al. (2009) in which, for the first time, the destruction of a cold and thin Milky Way analogue disk is demonstrated in the context of these common accretion events. Using high-resolution simulations, in both the collisionless regime and in hydrodynamical experiments, we show that the resultant disk scale heights are typically larger, and the stellar dynamical temperature significantly hotter, than that of the Galactic thick disk. We conclude that in order for the Milky Way to be as thin and cold as it is today, the accretion history of the Galaxy must have been unusually quiescent compared to median ΛCDM expectations.
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