2000ApJ...540...32G

We use cosmological hydrodynamic simulations to investigate the formation of galactic bulges within the framework of hierarchical clustering in a representative cold dark matter (CDM) cosmological model. We show that the largest objects forming at cosmological redshifts z∼4 resemble observed bulges of spiral galaxies or moderate-sized ellipticals in their general properties, such as size, shape, and density profile. This is consistent with observational data indicating the existence of ``old'' bulges and ellipticals at more moderate redshifts. These bulges are gas dominated at redshift z=3, with high rates of star formation, and would appear to be good candidates for small blue galaxies seen in the Hubble Deep Field.