Cosmic flexion

TL;DR

Cosmic flexion is a small-scale cosmological probe related to large-scale structure, offering unique constraints on the matter power spectrum, with formalism and forecasts for current and future surveys.

Contribution

This paper develops a comprehensive theoretical formalism for cosmic flexion, including correlation functions, and provides forecasts for its measurement in DES and future surveys.

Findings

Formalism for cosmic flexion correlations established.

Forecasts indicate potential for constraints in DES.

Future prospects promising for Stage IV experiments.

Abstract

Cosmic flexion, like cosmic shear, is a correlation function whose signal originates from the large-scale structure of the universe. Building on the observational success of cosmic shear, along with the unprecedented quality of large-scale cosmological datasets, the time is ripe to explore the practical constraints from cosmic flexion. Unlike cosmic shear, which has a broad window function for power, cosmic flexion is only measurable on small scales and therefore can uniquely place constraints on the small-scale matter power spectrum. Here, we present a full theoretical formalism for cosmic flexion, including both flexion-flexion and shear-flexion two-point correlations. We present forecasts for measuring cosmic flexion in the Dark Energy Survey (DES), a Stage III cosmological survey, and comment on the future prospects of measuring these cosmological flexion signals in the upcoming era of Stage IV experiments.