Affiliation:
1. Institute for Computational Cosmology, Department of Physics, University of Durham , South Road, Durham DH1 3LE, UK
Abstract
ABSTRACT
We use the GALFORM semi-analytical model of galaxy formation and the Planck-Millennium simulation to investigate the origins of stellar mass in galaxies and their spheroids. We compare the importance of mergers and disc instabilities, as well as the starbursts that they trigger. We find that the fraction of galaxy stellar mass formed ex situ (i.e. through mergers; fex) increases sharply from M* = 1011 M⊙ upwards, reaching 80 per cent at M* = 1011.3 M⊙. The massive end of the fex–M* relation does not evolve with redshift, in disagreement with other models. For low-mass galaxies we find larger ex situ contributions at z = 0 than in other models (7–12 per cent), with a decrease towards higher redshifts. Major mergers contribute roughly half of the ex situ mass, with minor mergers and smooth accretion of satellites both accounting for ≈25 per cent, almost independent of stellar mass and redshift. Mergers dominate in building up high-mass (M*, sph > 1011 M⊙) and low-mass (M*, sph < 108.5 M⊙) spheroids. Disc instabilities and their associated starbursts dominate for intermediate-mass spheroids (108.5 < M*, sph < 1011 M⊙) at z = 0. The mass regime where pseudo-bulges dominate is in agreement with observed pseudo-bulge fractions, but the peak value in the pseudo-bulge fraction predicted by GALFORM is likely too high. Starbursts induced by disc instabilities are the dominant channel for spheroid growth at all redshifts, while merger-induced starbursts are relatively negligible, except at very high redshifts (z > 5).
Publisher
Oxford University Press (OUP)
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
4 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献