Mass and Light of Abell 370: A Strong and Weak Lensing Analysis

TL;DR

This paper develops a new gravitational lens model of Abell 370 using combined strong and weak lensing data from Hubble Frontier Fields, providing insights into the cluster's mass distribution and its relation to stellar mass.

Contribution

It presents the first combined strong and weak lensing analysis of Abell 370 using Hubble Frontier Fields data, offering an independent validation of mass models and publicly sharing convergence, shear, and magnification maps.

Findings

Model aligns with other studies but shows differences due to methodology.

Total projected stellar to total mass ratio is approximately 0.011.

Results support consistency with previous measurements of stellar mass fractions in similar clusters.

Abstract

We present a new gravitational lens model of the Hubble Frontier Fields cluster Abell 370 ($z = 0.375$) using imaging and spectroscopy from Hubble Space Telescope and ground-based spectroscopy. We combine constraints from a catalog of 1344 weakly lensed galaxies and 39 multiply-imaged sources comprised of 114 multiple images, including a system of multiply-imaged candidates at $z=7.93 \pm 0.02$, to obtain a best-fit mass distribution using the cluster lens modeling code Strong and Weak Lensing United. As the only analysis of A370 using strong and weak lensing constraints from Hubble Frontier Fields data, our method provides an independent check on assumptions in other methods on the mass distribution. Convergence, shear, and magnification maps are made publicly available through the HFF website. We find that the model we produce is similar to models produced by other groups, with some exceptions due to the differences in lensing code methodology. In an effort to study how our total projected mass distribution traces light, we measure the stellar mass density distribution using Spitzer/Infrared Array Camera imaging. Comparing our total mass density to our stellar mass density in a radius of 0.3 Mpc, we find a mean projected stellar to total mass ratio of $\langle f* \rangle = 0.011 \pm 0.003$ (stat.) using the diet Salpeter initial mass function. This value is in general agreement with independent measurements of $\langle f* \rangle$ in clusters of similar total mass and redshift.