Issue EAS Publications Series Volume 10, 2003 JENAM 2002, Galactic & Stellar Dynamics Page(s) 79 DOI 10.1051/eas:2003134

Galactic & Stellar Dynamics
C. Boily, P. Patsis, S. Portegies Zwart, R. Spurzem and C. Theis (eds)
EAS Publications Series, Vol. 10, 2003
DOI: 10.1051/eas:2003134

Origin of Galactic Warps ^*

T. Tsuchiya

Astronomisches Rechen-Institut, Mönchhofstrasse 12-14, 69120 Heidelberg, Germany $^{\dagger}$ Current address: SGI Japan Ltd., 668-3, Moto-zaimoku-cho, Fushimi-ku, Kyoto 612-8043, Japan

Abstract
The origin of galactic warps is a long standing mystery. There has been progress recently in the theoretical understanding of the generation of warps, drawn from a reanalysis of the influence of a companion to a disc galaxy. A prominent example is found in the Milky Way - the LMC systems. Shortly after the discovery of the Milky Way's warp, it was shown that the direct torque from the LMC is too small to generate the observed warp in amount. We have performed numerical simulations in order to examine the effect of a live halo, as a mediator of the tidal interaction between the companion and the disc. We find with fairly realistic Milky Way models that the orbiting motion of the LMC excites massive wakes in the DM halo, and that these wakes produce larger torques on the disc than the companion alone. As a result the disc may develop a warp, of amplitude comparable to the one observed.

© EAS, EDP Sciences 2003

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