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We employ the earlier published proper motions of the newly discovered Antlia2 dwarf galaxy derived from Gaia data to calculate its orbital distribution inthe cosmologically recent past. Using these observationally motivated orbits,we calculate the effect of the Antlia 2 dwarf galaxy on the outer HI disk ofthe Milky Way, using both test particle and Smoothed Particle Hydrodynamicssimulations. We find that orbits with low pericenters, $\sim$ 10 kpc, producedisturbances that match the observed outer HI disk perturbations. We haveindependently recalculated the proper motion of the Antlia 2 dwarf from Gaiadata and found a proper motion of $(\mu_{\alpha}cos\delta, \mu_{\delta}) =(-0.068,0.032) \pm (0.023,-0.031)~\rm mas/yr$, which agrees with results fromTorrealba et al. (2019) within the errors, but gives lower mean pericenters,e.g., $\sim$ 15 kpc for our fiducial model of the Milky Way. We also show thatthe Sagittarius dwarf galaxy interaction does not match the observedperturbations in the outer gas disk. Thus, Antlia 2 may be the driver of theobserved large perturbations in the outer gas disk of the Galaxy. The currentlocation of the Antlia 2 dwarf galaxy closely matches that predicted by anearlier dynamical analysis (Chakrabarti \& Blitz 2009) of the dwarf that droveripples in the outer Galaxy, and, in particular, its orbit is nearly coplanarto the Galactic disk. If the Antlia 2 dwarf galaxy is responsible for theperturbations in the outer Galactic disk, it would have a specific range ofproper motions that we predict here; this can be tested soon with Gaia DR-3 andGaia DR-4 data.

Antlia2's role in driving the ripples in the outer gas disk of the Galaxy