IAUS379: Dynamical Masses of Local Group Galaxies

Understanding the origin of the stellar streams around the Milky Way can be of great relevance to learn about the history of the Milky Way and the formation of its substructures. A previous study on the Milky Way streams (Pawlowski et al. 2012) showed that many of these (7 out of 14) present a similar orientation to that of the disk of satellite galaxies (DoS) and the young globular clusters of the Milky Way. This suggests that the DoS, the young globular clusters and a large fraction of the Milky Way streams have a correlated origin. The authors named this group of subsystems the ``Vast POlar Structure" (VPOS), and proposed that it could have formed as a result of a past interaction between the Milky Way and the Andromeda galaxy. A more recent study (Riley et al. 2020) analysed 64 Milky Way streams and concluded that there is no evidence of clustering around the VPOS direction in the orbital poles of the Milky Way streams once the newly discovered streams are taken into account. In this work, we revise the distrubution of the orbital poles of the Milky Way streams in light of the latest stream dataset, which includes a total of 97 streams, improved measurments of their positions and dynamics and a more reliable method for obtaining their orbital poles.