Full-Shape Galaxy Power Spectra and the Curvature Tension

Abstract

With recent evidence for a possible "curvature tension" among early and late universe cosmological probes, Effective Field Theories of Large Scale Structure (EFTofLSS) have emerged as a promising new framework to generate constraints on $\hat{I}{\text{c◯}}_k$ that are independent of both CMB measurements, and some of the assumptions of flatness that enter into other large-scale structure analyses. In this work we use EFTofLSS to simultaneously constrain measurements from the 6dFGS, BOSS, and eBOSS catalogues, representing the most expansive full-shape investigation of curvature to date. Fitting the full-shape data with a BBN prior on $\hat{I}{\text{c◯}}_b{h}^2$ and fixed $n_s$, we measure $\hat{I}{\text{c◯}}_k=-0.089_{-0.046}^{+0.049}$, corresponding to a $\sim 2\ddot{I}ƒ$ preference for curvature. We argue that this result cannot be biased towards flatness by assumptions in the fitting methodology. Using the Bayesian evidence ratio our full-shape data assigns betting odds of 2:1 in favour of curvature, indicating present measurements remain broadly compatible with both flat and curved cosmological models. When our full-shape sample is combined with Planck 2018 CMB measurements, we break the geometric degeneracy and recover a joint fit on $\hat{I}{\text{c◯}}_k$ of $-0.0041_{-0.0021}^{+0.0026}$. Using the suspiciousness statistic (built on the standard Bayes factor), we find evidence for a moderate tension between Planck 2018 and our suite of full-shape measurements, at a significance of $1.76_{-0.11}^{+0.14}\ddot{I}ƒ$ ($p\sim 0.08\pm 0.02$). These results demonstrate the usefulness of full-shape clustering measurements as a CMB independent probe of curvature in the ongoing curvature tension debate.

14 pages, 7 figures, 7 tables