Baryon Acoustic Oscillations in the Ly-α forest of BOSS quasars
Bibliographic record
Abstract
We report a detection of the baryon acoustic oscillation (BAO) feature in the\nthree-dimensional correlation function of the transmitted flux fraction in the\n\\Lya forest of high-redshift quasars. The study uses 48,640 quasars in the\nredshift range $2.1\\le z \\le 3.5$ from the Baryon Oscillation Spectroscopic\nSurvey (BOSS) of the third generation of the Sloan Digital Sky Survey\n(SDSS-III). At a mean redshift $z=2.3$, we measure the monopole and quadrupole\ncomponents of the correlation function for separations in the range\n$20\\hMpc<r<200\\hMpc$. A peak in the correlation function is seen at a\nseparation equal to $(1.01\\pm0.03)$ times the distance expected for the BAO\npeak within a concordance $\\Lambda$CDM cosmology. This first detection of the\nBAO peak at high redshift, when the universe was strongly matter dominated,\nresults in constraints on the angular diameter distance $\\da$ and the expansion\nrate $H$ at $z=2.3$ that, combined with priors on $H_0$ and the baryon density,\nrequire the existence of dark energy. Combined with constraints derived from\nCosmic Microwave Background (CMB) observations, this result implies\n$H(z=2.3)=(224\\pm8){\\rm km\\,s^{-1}Mpc^{-1}}$, indicating that the time\nderivative of the cosmological scale parameter $\\dot{a}=H(z=2.3)/(1+z)$ is\nsignificantly greater than that measured with BAO at $z\\sim0.5$. This\ndemonstrates that the expansion was decelerating in the range $0.7<z<2.3$, as\nexpected from the matter domination during this epoch. Combined with\nmeasurements of $H_0$, one sees the pattern of deceleration followed by\nacceleration characteristic of a dark-energy dominated universe.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| 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) | 0.001 | 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".