Measurement of a Cosmographic Distance Ratio with Galaxy and CMB Lensing

TL;DR

This paper presents a geometric measurement of cosmological distances using galaxy and CMB lensing shear ratios, providing a novel test of the DM model over a large redshift range.

Contribution

It introduces a new method to measure cosmographic distance ratios by combining galaxy and CMB lensing shear data, canceling systematics and galaxy bias.

Findings

Measured a 17% distance ratio at z=0.53

Results are consistent with Planck DM predictions

Demonstrated the method's potential for cosmological tests

Abstract

We measure the gravitational lensing shear signal around dark matter halos hosting CMASS galaxies using light sources at $z\sim 1$ (background galaxies) and at the surface of last scattering at $z\sim 1100$ (the cosmic microwave background). The galaxy shear measurement uses data from the CFHTLenS survey, and the microwave background shear measurement uses data from the {\it Planck} satellite. The ratio of shears from these cross-correlations provides a purely geometric distance measurement across the longest possible cosmological lever arm. This is because the matter distribution around the halos, including uncertainties in galaxy bias and systematic errors such as miscentering, cancels in the ratio for halos in thin redshift slices. We measure this distance ratio in three different redshift slices of the CMASS sample, and combine them to obtain a $17\%$ measurement of the distance ratio, $r=0.390^{+0.070}_{-0.062}$ at an effective redshift of $z=0.53$. This is consistent with the predicted ratio from the {\it Planck} best-fit $\Lambda$CDM cosmology of $r=0.419$.