The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements and the strong power of f(z) 8(z) on constraining dark energy
Bibliographic record
Abstract
We present measurements of the anisotropic galaxy clustering from the Data Release 9 (DR9) CMASS sample of the Sloan Digital Sky Survey (SDSS)-III Baryon Oscillation Spectroscopic Survey (BOSS). We analyse the broad-range shape of the monopole and quadrupole correlation functions to obtain constraints, at the effective redshift z = 0.57 of the sample, on the Hubble expansion rate H(z), the angular-diameter distance DA(z), the normalized growth rate f (z)σ8(z), the physical matter density Ωmh2, and the biased amplitude of matter fluctuation bσ8(z). We obtain {H(0.57), DA(0.57), f (0.57)σ8(0.57), Ωmh2, bσ8(0.57)} = |$\lbrace 87.6_{-6.8}^{+6.7}$| kms−1 Mpc−1, 1396 ± 73 Mpc, 0.428 ± 0.066, |$0.126_{-0.010}^{+0.008}$|, 1.19 ± 0.14} and their covariance matrix as well. The parameters which are not well constrained by our galaxy clustering analysis are marginalized over with wide flat priors. Since no priors from other data sets [i.e. cosmic microwave background (CMB)] are adopted and no dark energy models are assumed, our results from BOSS CMASS galaxy clustering alone may be combined with other data sets, i.e. CMB, SNe, lensing or other galaxy clustering data to constrain the parameters of a given cosmological model. We show that the major power on constraining dark energy from the anisotropic galaxy clustering signal, as compared to the angular-averaged one (monopole), arises from including the normalized growth rate f (z)σ8(z). In the case of the cosmological model assuming a constant dark energy equation of state and a flat universe (wCDM), our single-probe CMASS constraints, combined with CMB (WMAP9+SPT), yield a value for the dark energy equation-of-state parameter of w = −0.90 ± 0.11. Therefore, it is important to include f (z)σ8(z) while investigating the nature of dark energy with current and upcoming large-scale galaxy surveys.
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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 | 0.000 | 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 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".