Measurement of the Weyl Potential Evolution and $E_G$ Statistic from KiDS-1000, BOSS and 2dFLenS

TL;DR

This study measures the Weyl potential and $E_G$ statistic using KiDS-1000, BOSS, and 2dFLenS data, finding mild deviations from $ ext{Lambda}$CDM at high redshift, influenced by the CMASS sample.

Contribution

It applies a model-independent framework to new datasets, revealing potential tensions with $ ext{Lambda}$CDM$ and exploring modified gravity models.

Findings

Weyl potential and $E_G$ are consistent with late-time constraints without CMB priors.

A mild $1.52\sigma$ deviation from $ ext{Lambda}$CDM is observed at high redshift with Planck18 priors.

Modified gravity models mildly prefer a suppressed high redshift Weyl potential.

Abstract

A recently developed model-independent approach to measuring the Weyl potential has shown some tensions with $\Lambda$CDM (Lambda Cold Dark Matter) in DES (Dark Energy Survey) Y3 data. We apply this framework to Kilo-Degree Survey (KiDS-1000) weak lensing and BOSS/2dFLenS galaxy clustering using the KiDS Cosmology Analysis Pipeline (KCAP) in two redshift bins. Without external CMB priors, both the Weyl potential and $E_G$ measurements are consistent with late time constraints. After imposing Planck18 priors, the low redshift bin remains compatible with General Relativity, whereas the high redshift bin shows a weaker Weyl potential and lower $E_G$, corresponding to a mild $1.52\sigma$ deviation from the $\Lambda$CDM cosmology. Furthermore, phenomenological modified gravity models show a mild preference for a suppressed high redshift Weyl potential, but late time data alone remain consistent with $\Lambda$CDM. Our results also suggest that this deviation is primarily driven by the specific high redshift CMASS sample, reflecting the well-known ``Lensing is low'' problem.