Friday, 7 May 2010

No bulge in the Milky Way?

In 1005.0385 (Our Milky Way as a pure-disk galaxy - A challenge for galaxy formation), Shen et al. model Milky Way like galaxies with N-body only code. The set up disk galaxies with bars of various strengths and evolve them dynamically for a bit. Then they add realistic bulges of various masses and see what is still feasible, giving the kinetic data of the BRAVA kinetic bulge observations. What they find is that the puffing up of the initially quite thin bar mimicks the presence of a bulge already, if viewed from the location of the Sun. When they include bulges of various masses, they find that the bulge is at most as massive as ~.1 times the mass of the disk. This is, they say, much less then required by 'the classical galaxy formation scenario'.