Cosmology with cosmic shear observations: a review

TL;DR

Cosmic shear, caused by weak gravitational lensing, is a key observational tool for understanding the Universe's structure, dark matter, and cosmic acceleration, with recent advances and future survey prospects.

Contribution

This review summarizes the principles, observational results, and future prospects of cosmic shear as a cosmological probe, highlighting recent progress and new techniques.

Findings

Cosmic shear measurements have provided robust constraints on dark matter and dark energy.

Recent surveys have significantly improved the precision of cosmic shear observations.

Future missions will enhance our understanding of the Universe's large-scale structure.

Abstract

Cosmic shear is the distortion of images of distant galaxies due to weak gravitational lensing by the large-scale structure in the Universe. Such images are coherently deformed by the tidal field of matter inhomogeneities along the line of sight. By measuring galaxy shape correlations, we can study the properties and evolution of structure on large scales as well as the geometry of the Universe. Thus, cosmic shear has become a powerful probe into the nature of dark matter and the origin of the current accelerated expansion of the Universe. Over the last years, cosmic shear has evolved into a reliable and robust cosmological probe, providing measurements of the expansion history of the Universe and the growth of its structure. We review here the principles of weak gravitational lensing and show how cosmic shear is interpreted in a cosmological context. Then we give an overview of weak-lensing measurements, and present the main observational cosmic-shear results since it was discovered 15 years ago, as well as the implications for cosmology. We then conclude with an outlook on the various future surveys and missions, for which cosmic shear is one of the main science drivers, and discuss promising new weak cosmological lensing techniques for future observations.