The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars
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...
| Main Authors: | , , , , , , , , , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
Oxford University Press
2017
|
| Online Access: | http://hdl.handle.net/1721.1/108509 https://orcid.org/0000-0001-8593-7692 https://orcid.org/0000-0002-5653-0786 |
| _version_ | 1811069148809134080 |
|---|---|
| author | Rodriguez-Gomez, Vicente Pillepich, Annalisa Sales, Laura V. Genel, Shy Zhu, Qirong Wellons, Sarah Nelson, Dylan Springel, Volker Ma, Chung-Pei Hernquist, Lars Vogelsberger, Mark Torrey, Paul A. |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Rodriguez-Gomez, Vicente Pillepich, Annalisa Sales, Laura V. Genel, Shy Zhu, Qirong Wellons, Sarah Nelson, Dylan Springel, Volker Ma, Chung-Pei Hernquist, Lars Vogelsberger, Mark Torrey, Paul A. |
| author_sort | Rodriguez-Gomez, Vicente |
| collection | MIT |
| description | 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 < μ < 1/4), ∼20 per cent from very minor mergers (μ < 1/10), and ∼10 per cent from stars that were stripped from surviving galaxies (e.g. flybys or ongoing mergers). These components are spatially segregated, with in situ stars dominating the innermost regions of galaxies, and ex situ stars being deposited at larger galactocentric distances in order of decreasing merger mass ratio. |
| first_indexed | 2024-09-23T08:06:29Z |
| format | Article |
| id | mit-1721.1/108509 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T08:06:29Z |
| publishDate | 2017 |
| publisher | Oxford University Press |
| record_format | dspace |
| spelling | mit-1721.1/1085092024-06-27T14:15:09Z The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars Rodriguez-Gomez, Vicente Pillepich, Annalisa Sales, Laura V. Genel, Shy Zhu, Qirong Wellons, Sarah Nelson, Dylan Springel, Volker Ma, Chung-Pei Hernquist, Lars Vogelsberger, Mark Torrey, Paul A. Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Vogelsberger, Mark Torrey, Paul A. 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 < μ < 1/4), ∼20 per cent from very minor mergers (μ < 1/10), and ∼10 per cent from stars that were stripped from surviving galaxies (e.g. flybys or ongoing mergers). These components are spatially segregated, with in situ stars dominating the innermost regions of galaxies, and ex situ stars being deposited at larger galactocentric distances in order of decreasing merger mass ratio. 2017-04-28T19:39:32Z 2017-04-28T19:39:32Z 2016-02 2016-02 Article http://purl.org/eprint/type/JournalArticle 0035-8711 1365-2966 http://hdl.handle.net/1721.1/108509 Rodriguez-Gomez, Vicente; Pillepich, Annalisa; Sales, Laura V.; Genel, Shy; Vogelsberger, Mark; Zhu, Qirong; Wellons, Sarah et al. “The Stellar Mass Assembly of Galaxies in the Illustris Simulation: Growth by Mergers and the Spatial Distribution of Accreted Stars.” Monthly Notices of the Royal Astronomical Society 458, no. 3 (February 26, 2016): 2371–2390. https://orcid.org/0000-0001-8593-7692 https://orcid.org/0000-0002-5653-0786 en_US http://dx.doi.org/10.1093/mnras/stw456 Monthly Notices of the Royal Astronomical Society Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf Oxford University Press arXiv |
| spellingShingle | Rodriguez-Gomez, Vicente Pillepich, Annalisa Sales, Laura V. Genel, Shy Zhu, Qirong Wellons, Sarah Nelson, Dylan Springel, Volker Ma, Chung-Pei Hernquist, Lars Vogelsberger, Mark Torrey, Paul A. The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars |
| title | The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars |
| title_full | The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars |
| title_fullStr | The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars |
| title_full_unstemmed | The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars |
| title_short | The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars |
| title_sort | stellar mass assembly of galaxies in the illustris simulation growth by mergers and the spatial distribution of accreted stars |
| url | http://hdl.handle.net/1721.1/108509 https://orcid.org/0000-0001-8593-7692 https://orcid.org/0000-0002-5653-0786 |
| work_keys_str_mv | AT rodriguezgomezvicente thestellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT pillepichannalisa thestellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT saleslaurav thestellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT genelshy thestellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT zhuqirong thestellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT wellonssarah thestellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT nelsondylan thestellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT springelvolker thestellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT machungpei thestellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT hernquistlars thestellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT vogelsbergermark thestellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT torreypaula thestellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT rodriguezgomezvicente stellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT pillepichannalisa stellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT saleslaurav stellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT genelshy stellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT zhuqirong stellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT wellonssarah stellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT nelsondylan stellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT springelvolker stellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT machungpei stellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT hernquistlars stellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT vogelsbergermark stellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars AT torreypaula stellarmassassemblyofgalaxiesintheillustrissimulationgrowthbymergersandthespatialdistributionofaccretedstars |