On the relevance of chaos for halo stars in the Solar Neighbourhood

NICOLÁS MAFFIONE; FACUNDO GÓMEZ; PABLO CINCOTTA; CLAUDIA GIORDANO; A. P. COOPER; B. W. O'SHEA

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015 vol. 453 p. 2830 - 2847

0035-8711

We show that diffusion due to chaotic mixing in the Neighbourhood of the Sun may not be 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. In the approximation of an analytical static triax ial model, 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 aHubble time do not exhibit significant diffusion in phase space.