Measuring Dark Matter Substructure with Galaxy-Galaxy Flexion Statistics

TL;DR

This paper proposes a novel method using galaxy-galaxy flexion variance to detect and measure dark matter substructures down to 10^9 solar masses, demonstrating its effectiveness through simulations and predictions for space surveys.

Contribution

It introduces a new flexion variance technique to constrain dark matter substructure properties, insensitive to overall galaxy halo mass, with potential for reliable detection in upcoming surveys.

Findings

Flexion variance effectively measures substructures in simulations.

Method is insensitive to total galaxy halo mass.

Predicted high signal-to-noise detection for subhalos down to 10^9 M_7 halos.

Abstract

It is of great interest to measure the properties of substructures in dark matter halos at galactic and cluster scales. Here we suggest a method to constrain substructure properties using the variance of weak gravitational flexion in a galaxy-galaxy lensing context. We show the effectiveness of flexion variance in measuring substructures in N-body simulations of dark matter halos, and present the expected galaxy-galaxy lensing signals. We show the insensitivity of the method to the overall galaxy halo mass, and predict the method's signal-to-noise for a space-based all-sky survey, showing that the presence of substructure down to 10^9 M_\odot halos can be reliably detected.