Constraints on Ω<sub><i>m</i></sub>and σ<sub>8</sub>from Weak Lensing in Red‐Sequence Cluster Survey Fields
Bibliographic record
Abstract
We have analyzed 53 deg 2 of R C -band imaging data from the Red-Sequence Cluster Survey (RCS) and measured the excess correlations in the shapes of galaxies on scales out to ~1 5. We separate the signal into an "E" (lensing) and "B" (systematics) mode, which allows us to study the contribution from residual systematics and intrinsic alignments. On scales larger than 10', we find no B mode, suggesting that the signal at those scales is caused solely by gravitational lensing. On smaller scales we find a small but significant B mode. This signal is also present when we select a sample of bright (20 < R C < 22) galaxies. These galaxies are rather insensitive to observational distortions, and we therefore conclude that the observed B mode is likely to be caused by intrinsic alignments. To minimize the effect of intrinsic alignments, we limit the cosmic shear analysis to galaxies with 22 < R C < 24. We derive joint constraints on Ω m and σ 8 by marginalizing over Γ, Ω Λ , and the source redshift distribution, using different priors. Marginalizing over Γ and Ω Λ , and using a flat prior for the source redshift distribution, yields a conservative constraint of σ 8 = 0.45 Ω (95% confidence). A better constraint is derived when we use Gaussian priors for Γ (from the Two-Degree Field survey) and Ω m + Ω Λ (from cosmic microwave background [CMB]), and the source redshift distribution. For this choice of priors, we find σ 8 = (0.46 )Ω (95% confidence). We also investigated whether the RCS data can be used to constrain Γ. Using our set of Gaussian priors, we find that we can only place a lower bound on Γ for which we find Γ > 0.1 + 0.16Ω m (95% confidence). Comparison of the RCS results with three other recent cosmic shear measurements shows excellent agreement. The current weak-lensing results are also in good agreement with CMB measurements, when we allow the reionization optical depth τ and the spectral index n s to vary. We present a simple demonstration of how the weak-lensing results can be used as a prior in the parameter estimation from CMB measurements to derive constraints on the reionization optical depth τ.
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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 | 0.004 | 0.017 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".