Evidence for Coupling between the Sagittarius Dwarf Galaxy and the Milky Way Warp

Using recent determinations of the mass and orbit of Sagittarius, I calculateits orbital angular momentum. From the latest observational data, I alsocalculate the angular momentum of the Milky Way's warp. I find that bothangular momenta are directed toward l=270, b=0, and have magnitude 2-8x10^12M_Sun kpc km s^-1, where the range in both cases reflects uncertainty in themass. The coincidence of the angular momenta is suggestive of a couplingbetween these systems. Direct gravitational torque of Sgr on the disk is ruledout as the coupling mechanism. Gravitational torque due to a wake in the haloand the impulsive deposition of momentum by a passage of Sgr through the diskare still both viable mechanisms pending better simulations to test theirpredictions on the observed Sgr-MW system.Comment: 11 pages, to appear in the February 1 issue of ApJ