MOKA: a new tool for Strong Lensing Studies

TL;DR

MOKA is a novel simulation tool that models realistic galaxy cluster lenses to study how their internal structures influence strong gravitational lensing signals, aiding dark matter research.

Contribution

The paper introduces MOKA, a new algorithm for simulating realistic cluster-scale gravitational lenses based on recent numerical simulation results.

Findings

Strong lensing cross sections are highly sensitive to halo concentration.

Inner density slope significantly affects lensing strength.

Halo triaxiality and central galaxies also influence lensing signals.

Abstract

Strong gravitational lensing is a powerful tool for probing the matter distribution in the cores of massive dark matter haloes. Recent and ongoing analyses of galaxy cluster surveys (MACS, CFHTLS, SDSS, SGAS, CLASH, LoCuSS) have adressed the question of the nature of the dark matter distribution in clusters. N-body simulations of cold dark-matter haloes consistently find that haloes should be characterized by a concentration-mass relation that decreases monotonically with halo mass, and populated by a large amount of substructures, representing the cores of accreted progenitor halos. It is important for our understanding of dark matter to test these predictions. We present MOKA, a new algorithm for simulating the gravitational lensing signal from cluster-sized haloes. It implements the most recent results from numerical simulations to create realistic cluster-scale lenses with properties independent of numerical resolution. We perform systematic studies of the strong lensing cross section as a function of halo structures. We find that the strong lensing cross sections depend most strongly on the concentration and on the inner slope of the density profile of a halo, followed in order of importance by halo triaxiality and the presence of a bright central galaxy.