Characterising the relevance of chaos in shaping the phase space structure of Milky way -- like stellar haloes in the Neighbourhood of the Sun

N. P. MAFFIONE; F.A. GOMEZ; P. M. CINCOTTA; C.M. GIORDANO; A. P. COOPER; B.W. O'SHEA

Santiago

Workshop; Satellites and Streams in Santiago; 2015

European Southern Observatory (ESO)

We demonstrate that diffusion due to chaotic mixing in the Neighbourhood of the Sun is not as relevant as previously suggested in erasing phase space signatures of past Galactic accretion events. For this purpose, we analyse Solar Neighbourhood--like volumes extracted from cosmological simulations that naturally account for chaotic orbital behaviour induced by the strongly triaxial and cuspy shape of the resulting dark matter haloes, among other factors. Our results show that a large fraction of stellar halo particles in such local volumes have chaos onset times (i.e., the timescale at which stars commonly associated with chaotic orbits will exhibit their chaotic behaviour) significantly larger than a Hubble time. Furthermore, particles that do present a chaotic behaviour within a Hubble time do not exhibit significant diffusion in phase space.