Testing origins of the Hubble sequence

A method for calculating the separate mass functions for disk, spheroid, and dwarf galaxies in hierarchical clustering models is applied to galaxy formation in the cold dark matter model to test theories of the origin of the major Hubble types. The procedure yields a galaxy distribution at a given redshift by combining the Press Schechter estimate of the halo mass function, simplified dynamics based on the spherical top-hat prescription, and fractions based on physical criteria and a Gaussian distribution of overdensities. Dwarf galaxies are defined as those galaxies which form within haloes with virial temperatures below about 10 to the 5.4 K. Also, two models are presented to differentiate between elliptical and spiral galaxies. 55 refs