A new observable for cosmic shear

TL;DR

This paper proposes a novel observable for cosmic shear measurement using galaxy orientation and radio polarization, which can improve shear detection by leveraging collective galaxy data and is unaffected by intrinsic alignment.

Contribution

Introduces a new observable based on galaxy orientation and polarization to measure cosmic shear, reducing intrinsic alignment issues and enhancing signal detection.

Findings

Potential for improved shear measurement accuracy

Method applicable to future SKA II survey data

Observable not affected by intrinsic galaxy alignments

Abstract

In this paper we introduce a new observable to measure cosmic shear. We show that if we can measure with good accuracy both, the orientation of a galaxy and the polarisation direction of its radio emission, the angle between them is sensitive to the foreground cosmic shear. Even if the signal-to-noise ratio for a single measurement is expected to be rather small, the fact that all galaxies in a given pixel are subject to the same shear can be used to overcome the noise. An additional advantage of this observable is that the signal is not plagued by intrinsic alignment. We estimate the SNR for the shear correlation functions measured in this way with the future SKA II survey.