ASTRODEBATA / Geraint Lewis: The Formation History of Andromeda's Halo: Clues from Globular Clusters

The Formation History of Andromeda's Halo: Clues from Globular Clusters

Geraint Lewis
(Sydney Institute for Astronomy, The University of Sydney, Australia)

The Pan-Andromeda Archaeological Survey of M31 has revealed a wealth of globular clusters out to 150 kpc. Roughly half of these halo globular clusters are associated with stellar substructures, streams, shells, and debris of tidally disrupting systems, whilst the remainder are not. A kinematic analysis of these two populations reveals distinct, orthogonal rotation signatures, suggestive of two distinct, separate accretion events, one ancient and the other modern. As well as exploring the implications of this result, I also explore the inner globular clusters of Andromeda, finding the outer halo kinematics imprinted on this inner sample, and providing further evidence for distinct accretion events into the halo.