Natures of clump-origin bulges: similarities to the Milky Way bulge
  Bulges in spiral galaxies have been supposed to be classified into two types:
classical bulges or pseudobulges. Classical bulges are thought to form by
galactic merger with bursty star formation, whereas pseudobulges are suggested
to form by secular evolution. Noguchi (1998, 1999) suggested another bulge
formation scenario, `clump-origin bulge'. He demonstrated using a numerical
simulation that a galactic disc forms clumpy structures in the early stage of
disc formation, then the clumps merge into a single bulge at the centre. I
perform a high-resolution N-body/SPH simulation for the formation of the
clump-origin bulge in an isolated galaxy model. I find that the clump-origin
bulge resembles pseudobulges in dynamical properties, but this bulge consists
of old and metal-rich stars. These natures, old metal-rich population but
pseudobulge-like structures, mean that the clump-origin bulge can not be simply
classified into classical bulges nor pseudobulges. From these results, I
discuss similarities of the clump-origin bulge to the Milky Way bulge.
