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摘要
En 中文
We revisit the dynamics of razor-thin, stone-cold, and self-gravitating discs. By recasting the equations into standard cylindrical coordinates, the linearized vertical dynamics of an exponential disc can be followed for several giga years on a laptop in a few minutes. An initially warped disc rapidly evolves into a flat inner region and an outward-propagating spiral corrugation wave that rapidly winds up and would quickly thicken a disc with non-zero radial-velocity dispersion. The Sgr dwarf galaxy generates a similar warp in the Galactic disc as it passes through pericentre, and the warp generated by the dwarf's last pericentre similar to 35Myr ago is remarkably similar to the warp traced by the Galaxy's H I disc. The resemblance to the observed warp is fleeting but its timing is perfect. For the adopted parameters, the amplitude of the model warp is a factor 3 too small, but there are several reasons for this being so. The marked flaring of our Galaxy's low-alpha disc just outside the solar circle can be explained as a legacy of earlier pericentres.
Keyword:
methods: numerical
Galaxy: kinematics and dynamics
galaxies: kinematics and dynamics
期刊
IF:
4.8
论文数:
7.0W
被引数:
25.0W
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