Full-shape cosmology analysis of SDSS-III BOSS galaxy power spectrum using emulator-based halo model: a $5\%$ determination of $σ_8$

Abstract

We present the results obtained from the full-shape cosmology analysis of the redshift-space power spectra for 4 galaxy samples of the SDSS-III BOSS DR12 galaxy catalog over 0.2 < z < 0.75. For the theoretical template, we use an emulator that was built from an ensemble set of N -body simulations, which enables fast and accurate computation of the redshift-space power spectrum of "halos". Combining with the halo occupation distribution to model the halo-galaxy connection, we can compute the redshift-space power spectrum of BOSS-like galaxies in less than a CPU second, for an input model under flat ΛCDM cosmology. In our cosmology inference, we use the monopole, quadrupole and hexadecapole moments of the redshift-space power spectrum and include 7 nuisance parameters, with broad priors, to model uncertainties in the halo-galaxy connection for each galaxy sample, but do not use any information on the abundance of galaxies. We demonstrate a validation of our analysis pipeline using the mock catalogs of BOSS-like galaxies, generated using different recipes of the halo-galaxy connection and including the assembly bias effect. Assuming weak priors on cosmological parameters, except for the BBN prior on Ω b h 2 and the CMB prior on ns, we show that our model well reproduces the BOSS power spectra. Including the power spectrum information up to kmax = 0.25 h Mpc −1 , we find Ωm = 0.300±0.011, H0 = 68.35 +1.21 −1.39 km s −1 Mpc −1 , and σ8 = 0.742 +0.035 −0.036 , for the mode and 68% credible interval, after marginalization over nuisance parameters including the halo-galaxy connection parameters. We find little improvement in the cosmological parameters beyond a maximum wavelength kmax 0.2 h Mpc −1 due to the shot noise domination and marginalization of the halo-galaxy connection parameters. Our results show a nice agreement with the Planck CMB results for Ωm and H0, but indicate a slight tension for σ8.

The BOSS DR12 Full-Shape Cosmology: $Λ$CDM Constraints from the Large-Scale Galaxy Power Spectrum and Bispectrum Monopole

“…An additional comparison is between our work and that of [21], which used an emulator-based approach to analyze the public BOSS data. Although the underlying model is very different to our approach, the posterior means and variances agree quite well except for σ 8 , for which [21] finds a somewhat larger value consistent with [20]. Given the significant difference between our methodologies, a thorough investigation of this discrepancy requires significant work.…”

Combined full shape analysis of BOSS galaxies and eBOSS quasars using an iterative emulator

“…Emulation has been gaining a lot of interest, as it allows to speed up the analysis by reducing the number of expensive function evaluations required by allowing to interpolate between model predictions at a set of points in the parameter space. This method has been used in a number of galaxy clustering analyses to directly emulate observables such as galaxy power spectrum (Kwan et al 2015) and correlation function (Zhai et al 2019) or model ingredients such as the redshift space power spectrum of halos (Kobayashi et al 2021). Nevertheless, when building an emulator one must consider how theory model uncertainty might propagate to the cosmological parameter space which is non-trivial and needs to be validated for each new statistic or range of scales employed.…”

Analysis method for 3D power spectrum of projected tensor field with fast estimator and window convolution modelling: an application to intrinsic alignments

“…where φ ≡ φ r,x 3 is the angle between r ⊥ and x1 4 The expressions of Eqs. ( 28)-( 30) are in analogy with the 2D (angular) statistics.…”

“…For example, the three-dimensional spatial distribution of galaxies, inferred by observed angular positions and photometric or spectroscopic redshifts of individual galaxies, has been used to constrain cosmological parameters of the standard ΛCDM model [e.g. 3,4], properties of the primordial perturbations [e.g., 5,6], and gravity theories beyond General Relativity [e.g . 7].…”