Blinded challenge for precision cosmology with large-scale structure: results from effective field theory for the redshift-space galaxy power spectrum

TL;DR

This work conducts a blinded, large-volume test of the Effective Field Theory of Large-Scale Structure (EFTofLSS) as a template for redshift-space galaxy clustering. By analyzing mock CMASS/LOWZ-like data with two independent pipelines under a flat $\Lambda$CDM cosmology, the authors demonstrate that EFTofLSS can recover the true cosmological parameters $H_0$, $\Omega_m$, and $A_s$ within sub-percent to $\sim$1–2$\sigma$ across a robust $k_{\max}$ range, while highlighting that higher-order effects can bias $A_s$ beyond certain scales. The enormous simulated volume allows a clean separation of theoretical systematics from statistical error, validating EFTofLSS as a robust method for precision cosmology in galaxy surveys and guiding the choice of $k_{\max}$ for current and future surveys like DESI. The study also provides insights into how prior treatment of nuisance EFT parameters influences parameter constraints and informs future improvements to EFT templates and analysis strategies.

Abstract

An accurate theoretical template for the galaxy power spectrum is a key for the success of ongoing and future spectroscopic surveys. We examine to what extent the Effective Field Theory of Large Scale Structure is able to provide such a template and correctly estimate cosmological parameters. To that end, we initiate a blinded challenge to infer cosmological parameters from the redshift-space power spectrum of high-resolution mock catalogs mimicking the BOSS galaxy sample but covering a hundred times larger cumulative volume. This gigantic simulation volume allows us to separate systematic bias due to theoretical modeling from the statistical error due to sample variance. The challenge task was to measure three unknown input parameters used in the simulation: the Hubble constant, the matter density fraction, and the clustering amplitude. We present analyses done by two independent teams, who have fitted the mock simulation data generated by yet another independent group. This allows us to avoid any confirmation bias by analyzers and pin down possible tuning of the specific EFT implementations. Both independent teams have recovered the true values of the input parameters within sub-percent statistical errors corresponding to the total simulation volume.

Figures (13)

• Figure 1: The abundance of halos per unit logarithmic mass interval (upper) and the mean number of mock galaxies per halo (lower) as a function of the virial mass of halos. The mean of the ten random realizations are shown at three output redshifts of the simulations as indicated by the figure legend.
• Figure 2: First three multipole moments (monopole, quadrupole and hexadecapole) of the power spectrum in redshift space measured from our mock galaxy catalogs at three redshifts (the solid lines). The $1$-$\sigma$ uncertainty intervals assuming the survey parameter of the SDSS Data Release 12 are shown by the shaded regions. Also shown by the error bars are taken from Ref. Beutler17 based on SDSS DR12. For these data points, the measurements from the sample in the North Galactic Cap (NGC) and the South Galactic Cap (SGC) are shown separately by different symbols as indicated by the figure legend. Note that the Alcock-Paczynski effect is artificially induced assuming $\Omega_\mathrm{m}=0.3$ in the redshift-distance conversion. The analysis teams can only access exactly the data vector shown in this figure. The analyses presented in this paper is based on the monopole and the quadrupole moments from the catalog at $z=0.61$.
• Figure 3: Marginalized posteriors for the three varied cosmological parameters as a function of $k_{\rm max}$ (quoted in $h\,\mathrm{Mpc}^{-1}$ in the figure legend) obtained by the East Coast Team. Dashed lines mark the input parameters which were revealed once the Team submitted its final result.
• Figure 4: Upper panel: Comparison of the data for the monopole and the quadrupole (the error bars are there, albeit barely visible) with the best-fit model (left panel) obtained by the East Coast Team. The residuals for the monopole and the quadrupole for the best-fit model with $\chi^2/{\rm dof}= 12/(24-9)$ (right panel). Note that the quadrupole data points are slightly shifted for better visibility. Lower panel: Different contributions to the monopole (left panel) and quadrupole (right panel) power spectra. The data errors and the two-loop estimate are also displayed. We plot the absolute values, some terms are negative.
• Figure 5: Marginalized posteriors for the three varied cosmological parameters as a function of $k_{\rm max}$ (quoted in $h\,\mathrm{Mpc}^{-1}$ in the figure legend) obtained by the West Coast Team. Dashed lines mark the input parameters which were revealed once the Team submitted its final result, similarly to Fig. \ref{['fig:contours1']}.