(This one is almost further to our previous discussions in threads on Rotation Curves)...
Found a really good paper on arXiv this morning. Reasonably recent also (April 2010):
Global disk model for galaxies NGC 1365, NGC 6946, NGC 7793, UGC 6446
Joanna Jałocha1, Łukasz Bratek1, Marek Kutschera and Piotr Skindzier.
Quote:
Recently, we have analyzed mass distribution in several spiral galaxies (Jałocha et al. 2007, 2008; Bratek et al. 2008). We find that for some galaxies it cannot be spherical at larger radii. Since we expect in this case a flattened mass distribution to better approximate the gravitational potential at larger radii than the spherical one, we apply the global disk model. We then find that mass distribution of luminous matter accounts for rotation curves of the examined galaxies.
There is also increasing number of studies whose authors, using more involved galaxy models than so far, conclude, contrary to earlier findings, that luminous matter accounts for rotation in the internal galactic regions. (Sellwood & Kosowsky 2000; Evans 2001; Palunas & Williams 2000; Williams, Bureau & Cappellari 2009). There is also possibility that rotation of galaxies in the outermost regions can be driven by magnetic fields, not by dark matter (Battaner, Garrido, Membrado & Florido 1992).
These results need to be seen properly in the context of non-baryonic dark matter searches. Currently, there is strong observational evidence of non-baryonic dark matter in clusters of galaxies, in particular, from gravitational lensing by clusters and from colliding clusters, as e.g. the Bul- let cluster (Clowe et al. 2006). Also, the cosmological model provides support to the non-baryonic dark matter hypothesis, albeit at a more theoretical level. On the other hand, direct searches give null results, except for DAMA/LIBRA (Bernabei et al. 2007), however, these results are disputable and have not been confirmed by other searchers
|
An interesting paper. Well balanced, too. They go at it from an 'anything's possible' perspective and put all the known ideas to the test.
Also very interesting to see them considering the possibility that Magnetic fields might be counteracting gravitational forces in the outer arms.
Very interesting.
Cheers