  We present new constraints on the masses of the halos hosting the Milky Way
and Andromeda galaxies derived using graph neural networks. Our models, trained
on thousands of state-of-the-art hydrodynamic simulations of the CAMELS
project, only make use of the positions, velocities and stellar masses of the
galaxies belonging to the halos, and are able to perform likelihood-free
inference on halo masses while accounting for both cosmological and
astrophysical uncertainties. Our constraints are in agreement with estimates
from other traditional methods.
