Full-shape cosmology analysis of the SDSS-III BOSS galaxy power spectrum using an emulator-based halo model: A 5% determination of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>σ</mml:mi><mml:mn>8</mml:mn></mml:msub></mml:math>
Аннотация
We present the results obtained from the full-shape cosmology analysis of the redshift-space power spectra for four 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 galaxy-halo 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 $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ cosmology. In our cosmology inference, we use the monopole, quadrupole, and hexadecapole moments of the redshift-space power spectrum and include seven nuisance parameters, with broad priors, to model uncertainties in the galaxy-halo 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 galaxy-halo connection and including the assembly bias effect. Assuming weak priors on cosmological parameters, except for the BBN prior on ${\mathrm{\ensuremath{\Omega}}}_{\mathrm{b}}{h}^{2}$ and the CMB prior on ${n}_{\mathrm{s}}$, we show that our model well reproduces the BOSS power spectra. Including the power-spectrum information up to ${k}_{\mathrm{max}}=0.25h\text{ }\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$, we find ${\mathrm{\ensuremath{\Omega}}}_{\mathrm{m}}=0.30{1}_{\ensuremath{-}0.011}^{+0.012}$, ${H}_{0}=68.2\ifmmode\pm\else\textpm\fi{}1.4\text{ }\text{ }\mathrm{km}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$, and ${\ensuremath{\sigma}}_{8}=0.78{6}_{\ensuremath{-}0.037}^{+0.036}$ for the mode and 68% credible interval, after marginalization over galaxy-halo connection parameters. We find little improvement in the cosmological parameters beyond a maximum wavelength ${k}_{\mathrm{max}}\ensuremath{\simeq}0.2h\text{ }\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$ due to the shot noise domination and marginalization of the galaxy-halo connection parameters. Our results are consistent with the Planck CMB results within $1\ensuremath{\sigma}$ statistical uncertainties.