Model-Independent Test for Gravity using Intensity Mapping and Galaxy Clustering

Abstract

We propose a novel method to measure the $E_G$ statistic from clustering alone. The $E_G$ statistic provides an elegant way of testing the consistency of General Relativity by comparing the geometry of the Universe, probed through gravitational lensing, with the motion of galaxies in that geometry. Current $E_G$ estimators combine galaxy clustering with gravitational lensing, measured either from cosmic shear or from CMB lensing. In this paper, we construct a novel estimator for $E_G$, using only clustering information obtained from two tracers of the large-scale structure: intensity mapping and galaxy clustering. In this estimator, both the velocity of galaxies and gravitational lensing are measured through their impact on clustering. We show that with this estimator, we can suppress the contaminations that affect other $E_G$ estimators and consequently test the validity of General Relativity robustly. We forecast that with the coming generation of surveys like HIRAX and Euclid, we will measure $E_G$ with a precision of up to 7% (3.9% for the more futuristic SKA2).

14 pages, 6 figures; v3: version matching published one

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Cited by in corpus (4)

• Cosmological Probes of Structure Growth and Tests of Gravity
• Testing General Relativity through the $E_G$ Statistic Using the Weyl Potential and Galaxy Velocities
• Toward testing gravity with LSST using $E_G$
• Probing gravity with non-linear clustering in redshift space