Cosmology with the galaxy bispectrum multipoles: Optimal estimation and application to BOSS data
Bibliographic record
Abstract
We present a framework for self-consistent cosmological analyses of the full-shape anisotropic bispectrum, including the quadrupole ($\ensuremath{\ell}=2$) and hexadecapole ($\ensuremath{\ell}=4$) moments. This features a novel window-free algorithm for extracting the latter quantities from data, derived using a maximum-likelihood prescription. Furthermore, we introduce a theoretical model for the bispectrum multipoles (which does not introduce new free parameters), and test both aspects of the pipeline on several high-fidelity mocks, including the PT Challenge suite of gigantic cumulative volume. This establishes that the systematic error is significantly below the statistical threshold, both for the measurement and modeling. As a realistic example, we extract the large-scale bispectrum multipoles from BOSS DR12 and analyze them in combination with the power spectrum data. Assuming a minimal $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ model, with a BBN prior on the baryon density and a Planck prior on ${n}_{s}$, we can extract the remaining cosmological parameters directly from the clustering data. The inclusion of the unwindowed higher-order ($\ensuremath{\ell}>0$) large-scale bispectrum multipoles is found to moderately improve one-dimensional cosmological parameter posteriors (at the 5%--10% level), though these multipoles are detected only in three out of four BOSS data segments at $\ensuremath{\approx}5\ensuremath{\sigma}$. Combining information from the power spectrum and bispectrum multipoles, the real space power spectrum, and the postreconstructed BAO data, we find ${H}_{0}=68.2\ifmmode\pm\else\textpm\fi{}0.8\text{ }\text{ }\mathrm{km}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$, ${\mathrm{\ensuremath{\Omega}}}_{m}=0.33\ifmmode\pm\else\textpm\fi{}0.01$ and ${\ensuremath{\sigma}}_{8}=0.736\ifmmode\pm\else\textpm\fi{}0.033$ (the tightest yet found in perturbative full-shape analyses). Our estimate of the growth parameter ${S}_{8}=0.77\ifmmode\pm\else\textpm\fi{}0.04$ agrees with both weak lensing and CMB results. The estimators and data used in this work have been made publicly available.
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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 | 0.015 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.003 |
| Research integrity | 0.001 | 0.002 |
| 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".