报告题目:HI in galaxies and the dark matter problem

报  告  人:Prof. Albert Bosma (LAM)

报告时间:Thursday, October 12, 2017, 02:00pm

报告地点:蒙民伟科技南楼 S727

报告摘要:

I will give a overview of HI in nearby galaxies, based on a recent review. 21-cm HI line observations are essential in the determination of "flat" rotation curves extending well beyond the optical image, which indicate the presence of dark matter in the outer parts of galaxies. Additional observations of stellar velocity dispersions at high spectral resolution are needed to break the so-called "degeneracy" in the mass modelling (i.e., the need to determine independently the mass-to-light ratio of the stellar components of a galaxy). Attempts to determine the shape of dark matter haloes are difficult, since there is a lot of extraplanar HI, in particular in active star forming galaxies. The currently popular Lambda-CDM model has still difficulties at galactic scales, and further 21-cm HI line observations are useful here, in particular for the core-cusp problem, as shown in recent publications. The upcoming new suite of HI surveys, to be undertaken by SKA pathfinders and precursors, will help develop this field of research.