The Local Group (LG) consists of two giant spiral galaxies, the Milky Way
(MW) and Andromeda (M31), and several smaller galaxies. The MW and M31 are
approaching each other at a radial velocity of about −109km\,s−1.
Observational evidence suggests that there is an overall infalling motion of
gas and galaxies in the LG, dominated by the dynamics of its two main members.
From our perspective, this flow imprints a velocity dipole pattern in the sky
when Galactic rotation is removed. We investigate the kinematic properties of
gas and galaxies in the LG using a suite of high-resolution simulations
performed by the {\sc Hestia} (High-resolution Environmental Simulations of The
Immediate Area) collaboration. Our simulations include the correct cosmography
surrounding LG-like regions. We build sky maps from the local, Galactic and LG
standard of rest reference frames. Our findings show that the establishment of
a radial velocity dipole near the preferred barycentre direction is a natural
outcome of simulation kinematics for material \textit{outside} the MW virial
radius after removing galaxy rotation when the relative radial velocity of MW
and M31 is similar to the observed value. These results favour a scenario where
gas and galaxies stream towards the LG barycentre, producing the observed
velocity dipole.Comment: 3 pages, 3 figures. To appear in the 64th Bulletin of the Argentine
Astronomical Society. arXiv admin note: substantial text overlap with
arXiv:2210.1558