The clustering of C IV and Si IV at the end of reionization
Bibliographic record
Abstract
Aims. We studied the clustering of metal absorption lines and the structures that they arise in as a function of cosmic time. We focused on the behaviour of C IV and Si IV ionic species. These C IV and Si IV absorption features are identified along a given quasar sightline. Methods. We exploited the two-point correlation function (2PCF) to investigate the clustering of these structures as a function of their separation. We utilised the E-XQR-30 data to perform a novel analysis at z > 5. We also drew on literature surveys (including XQ-100) of lower redshift quasars to investigate the possible evolution of this clustering towards cosmic noon (i.e. z ∼ 2 − 3). Results. We find no significant evolution with redshift when considering the separation of absorbers in velocity space. Since we were comparing data across a large interval of cosmic time, we also considered the separation between absorbers in the reference frame of physical distances. In this reference frame, we find that the amplitude of the clustering increases with cosmic time for both C IV and Si IV on scales of < 1500 physical kpc. Conclusions. For the first time, we assessed the 2PCF of C IV and Si IV close to the epoch of reionization utilising the absorber catalogue from the E-XQR-30 survey. We compared this with lower redshift data and find that, on small scales, the clustering of these structures grows with cosmic time. We compared these results to the clustering of galaxies in the GAEA simulations. It appears that the structures traced by C IV are broadly comparable to those of the galaxies from the considered simulations. The clustering is most similar to that of the galaxies with virial masses ( M ) of ∼ 10 10.5 M ⊙ . We do not draw direct comparisons at the smallest separations, to avoid the clustering traced by C IV at z ∼ 5 being dominated by contributions from absorbers within a single halo. We require tailor-made simulations to investigate the full range of factors contributing to the observed clustering of the detected metal absorbers. Future ground-based spectrographs will further facilitate surveys of absorbers at this epoch with increased sensitivity.
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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 | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".