Formation and assembly history of stellar components in galaxies as a
  function of stellar and halo mass
  Galaxy mass assembly is an end product of structure formation in the
$\Lambda$CDM cosmology. As an extension of Lee \& Yi (2013), we investigate the
assembly history of stellar components in galaxies as a function of halo
environments and stellar mass using semi-analytic approaches. In our fiducial
model, halo mass intrinsically determines the formation and assembly of the
stellar mass. Overall, the ex situ fraction slowly increases in central
galaxies with increasing halo mass but sharply increases for $\log
M_{*}/M_{\odot}\gtrsim11$. A similar trend is also found in satellite galaxies,
which implies that mergers are essential to build stellar masses above $\log
M_{*}/M_{\odot}\sim11$. We also examine the time evolution of the contribution
of mass growth channels. Mergers become the primary channel in the mass growth
of central galaxies when their host halo mass begins to exceed $\log
M_{200}/M_{\odot}\sim13$. However, satellite galaxies seldom reach the
merger-dominant phase despite their reduced star formation activities due to
environmental effects.
