The Three Hundred Project: A fast semi-analytic model emulator of hydrodynamical galaxy cluster simulations
Bibliographic record
Abstract
Next-generation photometric and spectroscopic surveys will detect faint galaxies in massive clusters, advancing our understanding of galaxy formation in dense environments. Comparing these observations with theoretical models requires high-resolution cluster simulations. Hydrodynamical simulations effectively resolve galaxy properties in halos; however, they face challenges in simulating low-mass galaxies within massive clusters due to computational limitations. On the other hand, dark matter-only (DMO) simulations can provide higher resolution but need models to populate subhalos with galaxies. In this work, we introduce a fast and efficient emulator of hydrodynamical simulations of galaxy clusters, based on the semi-analytic models (SAMs) SAGE and SAG. The calibration of the cluster galaxy properties in the SAMs was guided by the cluster galaxies from the hydrodynamical simulations at intermediate resolution, which represents the highest resolution achievable with current hydrodynamical simulations, ensuring consistency in properties such as stellar masses and luminosities across different redshifts. These SAMs are then applied to DMO simulations from THE THREE HUNDRED Project at three different resolutions. Our results show that the SAG model, unlike SAGE, more efficiently emulates the galaxy properties tested in this study even at the highest resolution. This improvement results from the detailed treatment of orphan galaxies, which are satellite galaxies that contribute significantly to the overall galaxy population. SAG enables the study of dwarf galaxies down to stellar masses of M* = 107 M⊙ at the highest resolution, which is an order of magnitude smaller than the stellar masses of galaxies in the hydrodynamical simulations at the intermediate resolution, corresponding to approximately four magnitudes fainter. This demonstrates that a SAM can be effectively calibrated to provide fast and accurate predictions for specific hydrodynamical simulations, offering a computationally efficient alternative for exploring galaxy populations in dense environments across higher resolutions.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".