Abstract

The theory that the Large Magellanic Cloud created the Milky Way's HI warp has been dismissed since Hunter and Toomre (1969) presented analytical evidence that the warp's magnitude requires an unrealistically close perigalacticon. However these analyses preceded by a decade the discovery of the massive galactic halos which strongly influence galactic dynamics. Recent analytical work by Weinberg (1995) suggests that a satellite perturbs the halo to create a warp with the proper sign and position, albeit of significantly lesser magnitude than the Milky Way's warp. Modern simulation codes permit galactic modeling within reactive halos and beg a revisitation of this theory.

To estimate the gravitational perturbations inflicted upon a galaxy by an orbiting satellite, I perform self-consistent dynamical simulations of a satellite galaxy orbiting a large disk galaxy. The model's parameters are chosen to resemble the Milky Way / Magellanic Cloud system. The particle model contains 120,000 particles; the disk represented with 1000 rigid concentric rings. The satellite orbits the disk at an inclination of 70° with respect to the disk plane, approaching to within 44 kpc. I find that a satellite of mass 1.44 x 10¹⁰ Mu, ~30% of the disk's mass, inclines the outer disk by ~2° within 2 satellite orbital times. Scaled to the Milky Way, this inclination is equivalent to 0.87 kpc at R = 25 kpc. While smaller by half than the Milky Way's warp, this response is nearly twice that found by Weinberg (1995). Duplication of the warp's sign and position suggests that the Large Magellanic Cloud provides a prominent, if not the primary, excitation source of the Galaxy's warp.