演講資訊

摘要：

The dynamics of an elliptical galaxy within a couple of effective radii can be probed effectively by stars. However, at larger distances planetary nebulae (PNe) replace stars as the tracer of the dynamics. Making use of the motion of PNe, Romanowsky et al. (2003) measured the dynamics of three luminous elliptical galaxies (NGC821, NGC3379 and NGC4494) at large distances from the galactic center. They found that little dark matter is needed up to 6 effective radii. Milgrom & Sanders (2003) showed that this result can be understood in the framework of MOdified Newtonian Dynamics (MOND). As more data are available in the past decade, we revisit this problem. We combine PNe data (up to 6 - 8 effective radii) and stellar data from SAURON of 7 elliptical galaxies. We conclude that the dynamics of these galaxies can be well explained by MOND.

Reference URL：

http://www.astro.ncu.edu.tw/people/researcher_bio.php?id=11