Full-shape cosmology analysis of SDSS-III BOSS galaxy power spectrum using emulator-based halo model: a 5%5\% determination of σ8\sigma_8

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 the flat $\Lambda$CDM cosmology. In our cosmology inference, we use the power spectrum monopole, quadrupole and hexadecapole and include 7 nuisance parameters 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 $\Omega_{\rm b}h^2$ and $n_{\rm s}$, we show that our model well reproduces the BOSS power spectra. Including the power spectrum information up to $k_{\rm max}=0.25\,h{\rm Mpc}^{-1}$, we find $\Omega_\mathrm{m}=0.301^{+0.012}_{-0.011}$, $H_0=68.2 \pm 1.4~\mathrm{km\,s}^{-1}\mathrm{Mpc}^{-1}$, and $\sigma_8=0.786^{+0.036}_{-0.037}$, for the mode and 68\% credible interval, after marginalization over nuisance parameters. We find little improvement in the cosmological parameters beyond a maximum wavelength $k_{\rm max}\simeq 0.2\,h\,{\rm Mpc}^{-1}$ due to the shot noise domination and marginalization of the halo-galaxy connection parameters. Our results are consistent with the Planck CMB results within $1\sigma$ statistical uncertainties.Comment: 27 pages, 18 figures, accepted by Phys. Rev. D. The main results are replaced with the analysis of the updated measurement of BOSS DR12 power spectrum provided by Beutler & McDonald (2021, arXiv:2106.06324

Robustness of Baryon Acoustic Oscillations Measurements with Photometric Redshift Uncertainties

We investigate the robustness of baryon acoustic oscillations (BAO) measurements with a photometric galaxy sample using mock galaxy catalogs with various sizes of photometric redshift (photo-$z$) uncertainties. We first investigate the robustness of BAO measurements, assuming we have a perfect knowledge of photo-$z$ uncertainties. We find that the BAO shift parameter $\alpha$ can be constrained in an unbiased manner for various sizes of photometric redshift uncertainties at $z=0.251$, $0.617$, and $1.03$ as long as the number density of galaxies is high. A sparse galaxy sample causes additional noise in the covariance matrix calculation and it can bias the constraint on $\alpha$. Next, we investigate the scenario where incorrect photometric redshift uncertainties are assumed in the fitting model and find that underestimating the photo-$z$ uncertainty leads to a degradation in the constraining power on $\alpha$. In addition, we investigate BAO measurements with a cross-correlation signal between a spec-$z$ sample and a photo-$z$ sample. We find BAO constraints are unbiased and slightly tighter than the auto-correlation signal of a photo-$z$ sample. We also quantify the constraining power on $\Omega_{\rm m0}$ assuming the LSST-like covariance and find that the 95\% confidence level is $\sigma(\Omega_{\rm m0})\sim0.03$-$0.05$ corresponding to the photo-$z$ uncertainties of 1\% to 3\% respectively. Finally, we examine whether the skewness in the photometric redshift can bias the constraint on $\alpha$ and confirm that the constraint on $\alpha$ is unbiased even if we use a fitting model assuming a Gaussian photo-$z$ uncertainty.Comment: 10 pages, 11 figures, 3 table

On the Assembly Bias of Cool Core Clusters Traced by Hα\alpha Nebulae

Do cool-core (CC) and noncool-core (NCC) clusters live in different environments? We make novel use of H$\alpha$ emission lines in the central galaxies of redMaPPer clusters as proxies to construct large (1,000's) samples of CC and NCC clusters, and measure their relative assembly bias using both clustering and weak lensing. We increase the statistical significance of the bias measurements from clustering by cross-correlating the clusters with an external galaxy redshift catalog from the Sloan Digital Sky Survey III, the LOWZ sample. Our cross-correlations can constrain assembly bias up to a statistical uncertainty of 6%. Given our H$\alpha$ criteria for CC and NCC, we find no significant differences in their clustering amplitude. Interpreting this difference as the absence of halo assembly bias, our results rule out the possibility of having different large-scale (tens of Mpc) environments as the source of diversity observed in cluster cores. Combined with recent observations of the overall mild evolution of CC and NCC properties, such as central density and CC fraction, this would suggest that either the cooling properties of the cluster core are determined early on solely by the local (<200 kpc) gas properties at formation or that local merging leads to stochastic CC relaxation and disruption in a periodic way, preserving the average population properties over time. Studying the small-scale clustering in clusters at high redshift would help shed light on the exact scenario.Comment: 17 pages, 9 figures, 2 tables, to be submitted to ApJ; comments welcom