The merger rate of galaxies in the Illustris simulation: a comparison with observations and semi-empirical models
We have constructed merger trees for galaxies in the Illustris simulation by directly tracking the baryonic content of subhaloes. These merger trees are used to calculate the galaxy–galaxy merger rate as a function of descendant stellar mass, progenitor stellar mass ratio, and redshift. We demonstra...
| Main Authors: | , , , , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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Oxford University Press
2015
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| Online Access: | http://hdl.handle.net/1721.1/98454 https://orcid.org/0000-0001-8593-7692 |
| _version_ | 1826203672232591360 |
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| author | Rodriguez-Gomez, Vicente Genel, Shy Vogelsberger, Mark Sijacki, Debora Pillepich, Annalisa Sales, Laura V. Torrey, Paul Snyder, Greg Nelson, Dylan Springel, Volker Ma, Chung-Pei Hernquist, Lars |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Rodriguez-Gomez, Vicente Genel, Shy Vogelsberger, Mark Sijacki, Debora Pillepich, Annalisa Sales, Laura V. Torrey, Paul Snyder, Greg Nelson, Dylan Springel, Volker Ma, Chung-Pei Hernquist, Lars |
| author_sort | Rodriguez-Gomez, Vicente |
| collection | MIT |
| description | We have constructed merger trees for galaxies in the Illustris simulation by directly tracking the baryonic content of subhaloes. These merger trees are used to calculate the galaxy–galaxy merger rate as a function of descendant stellar mass, progenitor stellar mass ratio, and redshift. We demonstrate that the most appropriate definition for the mass ratio of a galaxy–galaxy merger consists in taking both progenitor masses at the time when the secondary progenitor reaches its maximum stellar mass. Additionally, we avoid effects from ‘orphaned’ galaxies by allowing some objects to ‘skip’ a snapshot when finding a descendant, and by only considering mergers which show a well-defined ‘infall’ moment. Adopting these definitions, we obtain well-converged predictions for the galaxy–galaxy merger rate with the following main features, which are qualitatively similar to the halo–halo merger rate except for the last one: a strong correlation with redshift that evolves as ~(1 + z)[superscript 2.4–2.8], a power law with respect to mass ratio, and an increasing dependence on descendant stellar mass, which steepens significantly for descendant stellar masses greater than ~2 × 10[superscript 11] M[subscript ⊙]. These trends are consistent with observational constraints for medium-sized galaxies (M[subscript *] ≳ 10[superscript 10] M[subscript ⊙]), but in tension with some recent observations of the close pair fraction for massive galaxies (M[subscript *] ≳ 10[superscript 11] M[subscript ⊙]), which report a nearly constant or decreasing evolution with redshift. Finally, we provide a fitting function for the galaxy–galaxy merger rate which is accurate over a wide range of stellar masses, progenitor mass ratios, and redshifts. |
| first_indexed | 2024-09-23T12:41:14Z |
| format | Article |
| id | mit-1721.1/98454 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T12:41:14Z |
| publishDate | 2015 |
| publisher | Oxford University Press |
| record_format | dspace |
| spelling | mit-1721.1/984542022-09-28T09:24:47Z The merger rate of galaxies in the Illustris simulation: a comparison with observations and semi-empirical models Rodriguez-Gomez, Vicente Genel, Shy Vogelsberger, Mark Sijacki, Debora Pillepich, Annalisa Sales, Laura V. Torrey, Paul Snyder, Greg Nelson, Dylan Springel, Volker Ma, Chung-Pei Hernquist, Lars Massachusetts Institute of Technology. Department of Physics Vogelsberger, Mark We have constructed merger trees for galaxies in the Illustris simulation by directly tracking the baryonic content of subhaloes. These merger trees are used to calculate the galaxy–galaxy merger rate as a function of descendant stellar mass, progenitor stellar mass ratio, and redshift. We demonstrate that the most appropriate definition for the mass ratio of a galaxy–galaxy merger consists in taking both progenitor masses at the time when the secondary progenitor reaches its maximum stellar mass. Additionally, we avoid effects from ‘orphaned’ galaxies by allowing some objects to ‘skip’ a snapshot when finding a descendant, and by only considering mergers which show a well-defined ‘infall’ moment. Adopting these definitions, we obtain well-converged predictions for the galaxy–galaxy merger rate with the following main features, which are qualitatively similar to the halo–halo merger rate except for the last one: a strong correlation with redshift that evolves as ~(1 + z)[superscript 2.4–2.8], a power law with respect to mass ratio, and an increasing dependence on descendant stellar mass, which steepens significantly for descendant stellar masses greater than ~2 × 10[superscript 11] M[subscript ⊙]. These trends are consistent with observational constraints for medium-sized galaxies (M[subscript *] ≳ 10[superscript 10] M[subscript ⊙]), but in tension with some recent observations of the close pair fraction for massive galaxies (M[subscript *] ≳ 10[superscript 11] M[subscript ⊙]), which report a nearly constant or decreasing evolution with redshift. Finally, we provide a fitting function for the galaxy–galaxy merger rate which is accurate over a wide range of stellar masses, progenitor mass ratios, and redshifts. 2015-09-11T12:23:53Z 2015-09-11T12:23:53Z 2015-03 2015-02 Article http://purl.org/eprint/type/JournalArticle 0035-8711 1365-2966 http://hdl.handle.net/1721.1/98454 Rodriguez-Gomez, V., S. Genel, M. Vogelsberger, D. Sijacki, A. Pillepich, L. V. Sales, P. Torrey, et al. “The Merger Rate of Galaxies in the Illustris Simulation: a Comparison with Observations and Semi-Empirical Models.” Monthly Notices of the Royal Astronomical Society 449, no. 1 (March 14, 2015): 49–64. https://orcid.org/0000-0001-8593-7692 en_US http://dx.doi.org/10.1093/mnras/stv264 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 Genel, Shy Vogelsberger, Mark Sijacki, Debora Pillepich, Annalisa Sales, Laura V. Torrey, Paul Snyder, Greg Nelson, Dylan Springel, Volker Ma, Chung-Pei Hernquist, Lars The merger rate of galaxies in the Illustris simulation: a comparison with observations and semi-empirical models |
| title | The merger rate of galaxies in the Illustris simulation: a comparison with observations and semi-empirical models |
| title_full | The merger rate of galaxies in the Illustris simulation: a comparison with observations and semi-empirical models |
| title_fullStr | The merger rate of galaxies in the Illustris simulation: a comparison with observations and semi-empirical models |
| title_full_unstemmed | The merger rate of galaxies in the Illustris simulation: a comparison with observations and semi-empirical models |
| title_short | The merger rate of galaxies in the Illustris simulation: a comparison with observations and semi-empirical models |
| title_sort | merger rate of galaxies in the illustris simulation a comparison with observations and semi empirical models |
| url | http://hdl.handle.net/1721.1/98454 https://orcid.org/0000-0001-8593-7692 |
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