Measuring Dark Matter Substructure with Galaxy-Galaxy Flexion Statistics

Understand

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.