Correcting for the overabundance of low-mass quiescent galaxies in semi-analytic models
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arXiv
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| Format: | Preprint |
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2024
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| author | Harrold, Jimi E. Almaini, Omar Pearce, Frazer R. Yates, Robert M. |
| author_facet | Harrold, Jimi E. Almaini, Omar Pearce, Frazer R. Yates, Robert M. |
| contents | We compare the L-Galaxies semi-analytic model to deep observational data from the UKIDSS Ultra Deep Survey (UDS) across the redshift range $0.5 < z < 3$. We find that the over-abundance of low-mass, passive galaxies at high redshifts in the model can be attributed solely to the properties of `orphan' galaxies, i.e. satellite galaxies where the simulation has lost track of the host dark matter subhalo. We implement a simple model that boosts the star-formation rates in orphan galaxies by matching them to non-orphaned satellite galaxies at a similar evolutionary stage. This straightforward change largely addresses the discrepancy in the low-mass passive fraction across all redshifts. We find that the orphan problem is somewhat alleviated by higher resolution simulations, but the preservation of a larger gas reservoir in orphans is still required to produce a better fit to the observed space density of low-mass passive galaxies. Our findings are also robust to the precise definition of the passive galaxy population. In general, considering the vastly different prescriptions used for orphans in semi-analytic models, we recommend that they are analysed separately from the resolved satellite galaxy population, particularly with JWST observations reigniting interest in the low-mass regime in which they dominate. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_06018 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Correcting for the overabundance of low-mass quiescent galaxies in semi-analytic models Harrold, Jimi E. Almaini, Omar Pearce, Frazer R. Yates, Robert M. Astrophysics of Galaxies We compare the L-Galaxies semi-analytic model to deep observational data from the UKIDSS Ultra Deep Survey (UDS) across the redshift range $0.5 < z < 3$. We find that the over-abundance of low-mass, passive galaxies at high redshifts in the model can be attributed solely to the properties of `orphan' galaxies, i.e. satellite galaxies where the simulation has lost track of the host dark matter subhalo. We implement a simple model that boosts the star-formation rates in orphan galaxies by matching them to non-orphaned satellite galaxies at a similar evolutionary stage. This straightforward change largely addresses the discrepancy in the low-mass passive fraction across all redshifts. We find that the orphan problem is somewhat alleviated by higher resolution simulations, but the preservation of a larger gas reservoir in orphans is still required to produce a better fit to the observed space density of low-mass passive galaxies. Our findings are also robust to the precise definition of the passive galaxy population. In general, considering the vastly different prescriptions used for orphans in semi-analytic models, we recommend that they are analysed separately from the resolved satellite galaxy population, particularly with JWST observations reigniting interest in the low-mass regime in which they dominate. |
| title | Correcting for the overabundance of low-mass quiescent galaxies in semi-analytic models |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2405.06018 |