The hierarchical Cold Dark Matter (CDM) structure formation scenario has proven remarkably successful on large (cosmological) scales. On galactic scales it has encountered a number of problems, most notably the angular momentum problem, the over-cooling problem, the missing satellites problem and the central cusps problem. Inclusion of the effects of energetic stellar feedback processes in galaxy formation simulations may help to cure a number of these problems as indicated by, e.g., the “toy” models of Sommer-Larsen et al. (1999, SLGV). Recently Sommer-Larsen & Dolgov (2001, SLD) showed that by going from the CDM structure formation scenario to warm dark matter (WDM) scenarios one can alleviate and possibly even completely overcome the angular momentum problem, and complementary work of Colin et al. (2000) shows this to be the case also for other of the above problems. Fine-tuning of the warm dark matter particle mass to about 1 keV is required, however. In contrast the salient feature about “conventional” CDM is that as long as the dark matter particles are much heavier than one keV, the actual particle mass does not matter for structure formation.
We have recently completed a series of considerably more elaborate CDM galaxy formation simulations with very encouraging results: We find that a mix of disk, lenticular and elliptical galaxies can be obtained in fully cosmological (ΛCDM), gravity/hydro simulations invoking star-formation, energetic stellar feedback processes and a meta-galactic UV field. These results, together with results on disk gas infall histories and stellar age distributions, hot halo gas properties, global star formation histories etc. are presented in detail in Sommer-Larsen et al. (2002).