Cosmic shear with Einstein rings

TL;DR

This paper proposes using Einstein rings as standard shapes to measure external shear, offering a new method to improve cosmic shear measurements and enhance understanding of the universe's large-scale structure.

Contribution

It introduces a novel approach to utilize Einstein rings as standard shapes for cosmic shear analysis, addressing shape noise and intrinsic alignments.

Findings

Einstein rings can serve as standard shapes for shear measurement

This method is expected to be competitive in the Euclid era

It provides a complementary probe of large-scale structure

Abstract

Cosmic shear is a key probe of modern cosmology. Amongst its challenges are shape noise and intrinsic alignments, both due to our ignorance of the unlensed shape of the source galaxies. I argue here that Einstein rings may be used as standard shapes to measure the external shear along their line of sight. In the Euclid era, this new observable is expected to be a competitive and complementary probe of the large-scale structure of the Universe.