Is the large-scale structure traced by the BOSS LOWZ galaxies consistent with Planck\textit{Planck}?

Abstract

Recently, several studies reported a significant discrepancy between the clustering and lensing of the Baryon Oscillation Spectroscopic Survey (BOSS) galaxies in the Planck\textit{Planck} cosmology. We construct a simple yet powerful model based on the linear theory to assess whether this discrepancy points toward deviations from Planck\textit{Planck}. Focusing on scales 10<R<3010<R<30 hβˆ’1Mpch^{-1}\mathrm{Mpc}, we model the amplitudes of clustering and lensing of BOSS LOWZ galaxies using three parameters: galaxy bias bgb_\mathrm{g}, galaxy-matter cross-correlation coefficient rgmr_\mathrm{gm}, and AA, defined as the ratio between the true and Planck\textit{Planck} values of Οƒ8\sigma_8. Using the cross-correlation matrix as a diagnostic, we detect systematic uncertainties that drive spurious correlations among the low-mass galaxies. After building a clean LOWZ sample with rgm∼1r_\mathrm{gm}\sim1, we derive a joint constraint of bgb_\mathrm{g} and AA from clustering+lensing, yielding bg=2.47βˆ’0.30+0.36b_\mathrm{g}=2.47_{-0.30}^{+0.36} and A=0.81βˆ’0.09+0.10A=0.81_{-0.09}^{+0.10}, i.e., a 2Οƒ2\sigma tension with Planck\textit{Planck}. However, due to the strong degeneracy between bgb_\mathrm{g} and AA, systematic uncertainties in bgb_\mathrm{g} could masquerade as a tension with A=1A=1. To ascertain this possibility, we develop a new method to measure bgb_\mathrm{g} from the cluster-galaxy cross-correlation and cluster weak lensing using an overlapping cluster sample. By applying the independent bias measurement (bg=1.76Β±0.22b_\mathrm{g}=1.76\pm0.22) as a prior, we successfully break the degeneracy and derive stringent constraints of bg=2.02βˆ’0.15+0.16b_\mathrm{g}=2.02_{-0.15}^{+0.16} and A=0.96Β±0.07A=0.96\pm0.07. Therefore, our result suggests that the large-scale clustering and lensing of LOWZ galaxies are consistent with Planck\textit{Planck}, while the different bias estimates may be related to some observational systematics in the target selection.Comment: 8 pages, 5 figures, comments welcome

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