Probing gravity with a joint analysis of galaxy and CMB lensing and SDSS spectroscopy

TL;DR

This paper measures the gravity probe E_G using galaxy and CMB lensing data from SDSS, BOSS, and Planck, finding results consistent with the Planck ΛCDM model and analyzing redshift evolution.

Contribution

It provides the first joint analysis of galaxy and CMB lensing to measure E_G across different redshifts, testing gravity predictions with systematic uncertainty estimates.

Findings

E_G measurements are consistent with Planck ΛCDM predictions.

Systematic uncertainties are subdominant to statistical errors.

Redshift evolution of E_G aligns with theoretical models.

Abstract

We present measurements of $E_G$, a probe of gravity from large-scale structure, using BOSS LOWZ and CMASS spectroscopic samples, with lensing measurements from SDSS (galaxy lensing) and Planck (CMB lensing). Using SDSS lensing and the BOSS LOWZ sample, we measure $\langle{E_G}\rangle=0.40^{+0.05}_{-0.04}$ (stat), $\pm 0.026$ (systematic), consistent with the predicted value from the Planck $\Lambda$CDM model, $E_G=0.46$. Using CMB lensing, we measure $\langle{E_G}\rangle=0.46^{+0.08}_{-0.09}$ (stat) for LOWZ (statistically consistent with galaxy lensing and Planck predictions) and $\langle{E_G}\rangle=0.39^{+0.05}_{-0.05}$ (stat) for the CMASS sample, consistent with the Planck prediction of $E_G=0.40$ given the higher redshift of the sample. We also study the redshift evolution of $E_G$ by splitting the LOWZ sample into two samples based on redshift, with results being consistent with model predictions. We estimate systematic uncertainties on the above $\langle{E_G}\rangle$ numbers to be $\sim 6$% (when using galaxy-galaxy lensing) or $\sim 3$% (when using CMB lensing), subdominant to the quoted statistical errors. These systematic error budgets are dominated by observational systematics in galaxy-galaxy lensing and by theoretical modeling uncertainties, respectively. We do not estimate observational systematics in galaxy-CMB lensing cross correlations.