Weak-Lensing Results from the 75 Square Degree Cerro Tololo Inter-American Observatory Survey
Bibliographic record
Abstract
We measure seeing-corrected ellipticities for 2 × 10 6 galaxies with magnitude R ≤ 23 in 12 widely separated fields totaling 75 deg 2 of sky. At angular scales ≳30', ellipticity correlations are detected at high significance and exhibit nearly the pure " E mode" behavior expected of weak gravitational lensing. Even when smoothed to the full field size of 2 5, which is ≈25 h -1 Mpc at the lens distances, an rms shear variance of ⟨γ 2 ⟩ 1/2 = 0.0012 ± 0.0003 is detected. At smaller angular scales, there is significant " B -mode" power, an indication of residual uncorrected point-spread function distortions. The data at scales above 30' constrain the power spectrum of matter fluctuations on comoving scales of ≈10 h -1 Mpc to have σ 8 (Ω m /0.3) 0.57 = 0.71 (95% confidence level, ΛCDM, Γ = 0.21), where the systematic error includes statistical and calibration uncertainties, cosmic variance, and a conservative estimate of systematic contamination based upon the detected B -mode signal. This normalization of the power spectrum is lower than, but generally consistent with, previous weak-lensing results, is at the lower end of the σ 8 range from various analyses of galaxy cluster abundances, and agrees with recent determinations from cosmic microwave background and galaxy clustering. The large and dispersed sky coverage of our survey reduces random errors and cosmic variance, while the relatively shallow depth allows us to use existing redshift survey data to reduce systematic uncertainties in the N ( z ) distribution to insignificance. Reanalysis of the data with more sophisticated algorithms will hopefully reduce the systematic ( B mode) contamination and allow more precise, multidimensional constraint of cosmological parameters.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| 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) | 0.003 | 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".