The role of submillimetre galaxies in hierarchical galaxy formation
  We study the role of submillimetre galaxies (SMGs) in the galaxy formation
process in the Lambda Cold Dark Matter cosmology. We use the Baugh et al.
(2005) semi-analytical model, which matches the observed SMG number counts and
redshift distribution by assuming a top-heavy initial mass function (IMF) in
bursts triggered by galaxy mergers. We build galaxy merger trees and follow the
evolution and properties of SMGs and their descendants. Our primary sample of
model SMGs consists of galaxies which had 850 mu fluxes brighter than 5 mJy at
some redshift z>1. Our model predicts that the present-day descendants of such
SMGs cover a wide range of stellar masses ~ 10^{10} - 10^{12} Msun/h, with a
median ~ 10^{11} Msun/h, and that more than 70% of these descendants are
bulge-dominated. More than 50% of present day galaxies with stellar masses
larger than 7 x 10^{11} Msun/h are predicted to be descendants of such SMGs. We
find that although SMGs make an important contribution to the total star
formation rate at z~2, the final stellar mass produced in the submillimetre
phase contributes only 0.2% of the total present-day stellar mass, and 2% of
the stellar mass of SMG descendants, in stark contrast to the popular picture
in which the SMG phase marks the production of the bulk of the mass of present
day massive ellipticals.
