The impact of mergers on relaxed X-ray clusters – II. Effects on global X-ray and Sunyaev–Zel'dovich properties and their scaling relations
Bibliographic record
Abstract
We use the suite of simulations presented by Poole et al. to examine global X-ray and Sunyaev–Zel'dovich (SZ) observables for systems of merging relaxed X-ray clusters. The time evolution of our merging systems' X-ray luminosities, temperatures, total mass measures, SZ central Compton parameters and integrated SZ fluxes are presented and the resulting impact on their scaling relations examined. In all cases, and for all parameters, we observe a common time evolution: two rapid transient increases during first and second pericentric passage, with interceding values near or below their initial levels. This is in good qualitative agreement with previous idealized merger simulations, although we find several important differences related to the inclusion of radiative cooling in our simulations. These trends translate into a generic evolution in the scaling-relation planes as well: a rapid transient roughly along the mass scaling relations, a subsequent slow drift across the scatter until virialization, followed by a slow evolution along and up the mass scaling relations as cooling recovers in the cluster cores. However, this drift is not sufficient to account for the observed scatter in the scaling relations. We also study the effects of mergers on several theoretical temperature measures of the intracluster medium: emission-weighted measures (Tew), the spectroscopic-like measure (Tsl) proposed by Mazzotta et al. and plasma model fits to the integrated spectrum of the system (Tspec). We find that Tsl tracks Tspec for the entire duration of our mergers, illustrating that it remains a good tool for observational comparison even for highly disturbed systems. Furthermore, the transient temperature increases produced during first and second pericentric passage are 15–40 per cent larger for Tew than for Tsl or Tspec. This suggests that the effects of transient temperature increases on σ8 and ΩM derived by Randall et al. are over estimated. Lastly, we examine the X-ray SZ proxy proposed by Kravtsov, Vikhlinin & Nagai (2006) and find that the tight mass scaling relation they predict remains secure through the entire duration of a merger event, independent of projection effects.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".