Published in
Oxford University Press (OUP), Monthly Notices of the Royal Astronomical Society, p. stw456
DOI: 10.1093/mnras/stw456
Links
- ORCID
- ORCID
- ORCID
- ORCID
- Oxford University Press (OUP) | PDF
- [nrs.harvard.edu] | PDF
- [dash.harvard.edu] | PDF
- [authors.library.caltech.edu] | PDF
- [authors.library.caltech.edu] | PDF
- [dspace.mit.edu] | PDF
- [arxiv.org] | PDF
- [arxiv.org] | PDF
Tools
The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars
,
Annalisa Pillepich,
Laura V. Sales ,
Shy Genel,
Mark Vogelsberger,
Qirong Zhu,
Sarah Wellons ,
Dylan Nelson,
Volker Springel,
Paul Torrey ,
Chung-Pei Ma,
Lars Eric Hernquist
Full text: Download
Abstract
We use the Illustris simulation to study the relative contributions of in situ star formation and stellar accretion to the build-up of galaxies over an unprecedentedly wide range of masses (M* = 109-1012 M⊙), galaxy types, environments, and assembly histories. We find that the ‘two-phase’ picture of galaxy formation predicted by some models is a good approximation only for the most massive galaxies in our simulation – namely, the stellar mass growth of galaxies below a few times 1011 M⊙ is dominated by in situ star formation at all redshifts. The fraction of the total stellar mass of galaxies at z = 0 contributed by accreted stars shows a strong dependence on galaxy stellar mass, ranging from about 10 per cent for Milky Way-sized galaxies to over 80 per cent for M* ≈ 1012 M⊙ objects, yet with a large galaxy-to-galaxy variation. At a fixed stellar mass, elliptical galaxies and those formed at the centres of younger haloes exhibit larger fractions of ex situ stars than disc-like galaxies and those formed in older haloes. On average, ∼50 per cent of the ex situ stellar mass comes from major mergers (stellar mass ratio μ > 1/4), ∼20 per cent from minor mergers (1/10