  Gas-rich disks in the early universe are highly turbulent and have giant
star-forming clumps. Models suggest the clumps form by gravitational
instabilities, and if they resist disruption by star formation, then they
interact, lose angular momentum, and migrate to the center to form a bulge.
Here we study the properties of the bulges formed by this mechanism. They are
all thick, slowly rotating, and have a high Sersic index, like classical
bulges. Their rapid formation should also give them relatively high
alpha-element abundances. We consider fourteen low-resolution models and four
high-resolution models, three of which have supernova feedback. All models have
an active halo, stellar disk, and gaseous disk, three of the models have a
pre-existing bulge and three others have a cuspy dark matter halo. All show the
same basic result except the one with the highest feedback, in which the clumps
are quickly destroyed and the disk thickens too much. The coalescence of
massive disk clumps in the center of a galaxy is like a major merger in terms
of orbital mixing. It differs by leaving a bulge with no specific dark matter
component, unlike the merger of individual galaxies. Normal supernova feedback
has little effect because the high turbulent speed in the gas produces tightly
bound clumps. A variety of indirect observations support the model, including
clumpy disks with young bulges at high redshift and bulges with relatively
little dark matter.
