An Evaluation of 10 Lensing Models of the Frontier Fields Cluster MACSJ0416.1-2403

TL;DR

This paper evaluates ten gravitational lensing models of the galaxy cluster MACSJ0416.1-2403 using new spectroscopic data, assessing their accuracy in predicting multiple images and source positions to improve lens modeling techniques.

Contribution

It introduces an independent comparison method based on source plane RMS to evaluate and compare the performance of existing lens models for a specific galaxy cluster.

Findings

Models show varying accuracy in predicting multiple images.

Source plane scatter depends on source location and redshift.

The comparison method effectively quantifies model performance.

Abstract

Galaxy clusters can act as gravitational lenses to magnify the universe behind them, allowing us to see deep into the early universe. The Hubble Space Telescope Frontier Fields program (Lotz et al. 2017) uses six galaxy clusters imaged by Hubble to discover and study galaxies at z ~ 5-10. Seven independent teams developed lens models and derived magnifications for each galaxy cluster, based on positional and redshift constraints from the best available data at the time. In this work we evaluate ten models for MACSJ0416.1-2403, which were made public in 2015, by contrasting them with new spectroscopic redshifts that were measured in 2016 (Caminha et al. 2017). We developed an independent comparison method that uses the source plane root-mean-square as a metric of lensing model performance. Our analysis quantifies the ability of models to predict unknown multiple images. We examine the source plane scatter of multiply-imaged systems and explore dependence of the scatter on the location and the redshift of the background sources. The analysis we present evaluates the performance of the different algorithms in the specific case of the MACSJ0416.1-2403 models.