Key points are not available for this paper at this time.
The violent hierarchical nature of the Lambda-Cold Dark Matter cosmology poses serious difficulties for the formation of disk galaxies. To help resolve these issues, we describe a new, merger-driven scenario for the cosmological formation of disk galaxies that supplements the standard model based on dissipational collapse. In our picture, large gaseous disks are produced from high-angular momentum mergers of gas-rich progenitors. Pressurization from the multiphase structure of the interstellar medium and thermal feedback from supermassive black holes prevents the complete conversion of gas into stars during the merger, and if enough gas remains to form a disk the remnant eventually resembles a disk galaxy. We perform numerical simulations of galaxy mergers to demonstrate that disks can build angular momentum through mergers and the degree of rotational support of the baryons in the merger remnant is directly related to feedback processes associated with star formation and black hole growth. The correlation between black hole mass and the stellar velocity dispersion is connected to the formation of galactic disks as feedback from black hole growth limits the mass of the bulge component and increases the available gas supply for forming rapidly rotating stellar disks. We suggest that the hierarchical nature of the -Cold Dark Matter cosmology, the physics of the interstellar gas, and the growth of supermassive black holes can act together to form spiral galaxies by building the angular momentum of disks through gas-rich mergers. Our proposed scenario is especially important for galaxy formation at high redshifts, where gas-rich mergers are believed to be more common than in the local Universe.
Robertson et al. (Fri,) studied this question.