New high-precision strong lensing modeling of Abell 2744

Abstract

We present a new strong lensing (SL) model of the Hubble Frontier Fields (HFF) galaxy cluster Abell 2744, at z = 0.3072, by exploiting archival Hubble Space Telescope (HST) multiband imaging and Multi Unit Spectroscopic Explorer (MUSE) follow-up spectroscopy. The lens model considers 90 spectroscopically confirmed multiple images (from 30 background sources), representing the largest secure sample for this cluster field prior to the recently acquired James Webb Space Telescope (JWST) observations. The inclusion of the substructures within several extended sources as model constraints allowed us to accurately characterize the inner total mass distribution of the cluster and the position of the cluster critical lines. We included the lensing contribution of 225 cluster members, 202 of which are spectroscopically confirmed. We complemented this sample with 23 photometric member galaxies that are identified with a convolution neural network methodology with a high degree of purity. We also measured the internal velocity dispersion of 85 cluster galaxies, down to m F160W = 22, to independently estimate the role of the subhalo mass component in the lens model. We investigated the effect of the cluster environment on the total mass reconstruction of the cluster core with two different mass parameterizations. We considered the mass contribution from three external clumps, either based on previous weak lensing studies, or extended HST imaging of luminous members around the cluster core. In the latter case, the observed positions of the multiple images were better reproduced, with a remarkable accuracy of 0 ′′ .37, a factor of ∼ 2 smaller than previous lens models, which exploited the same HST and MUSE data sets. As part of this work, we developed and made publicly available a Strong Lensing Online Tool (SLOT) to exploit the predictive power and the full statistical information of this and future models, through a simple graphical interface. We plan to apply our new high-precision SL model to the first analysis of the Grism Lens-Amplified Survey from Space-JWST-Early Release Science (GLASS-JWST-ERS) program, specifically to measure the intrinsic physical properties of high-z galaxies from robust magnification maps.

A state-of-the-art strong-lensing model of MACS J0416.1−2403 with the largest sample of spectroscopic multiple images

“…The M0416 lens model presented here will be made publicly available with the publication of this paper through our newly developed Strong Lensing Online Tool, also known as SLOT (Bergamini et al 2023). With a simple graphical interface, SLOT offers the opportunity for non-lensing experts to access all the results and to exploit the predictive power of our models for their studies, specifically those based on upcoming JWST observations of M0416, which will reveal even more multiple images.…”

“…Going beyond the analysis presented in R21, we identify multiply-lensed, nearly point-like substructures inside most of these images that are used as constraints in our model. The inclusion of these sub-knots in the lens model proved to be extremely useful to reconstruct the fine details of the cluster gravitational potential and the positions of the critical lines (see also Grillo et al 2016;Bergamini et al 2023). For all the new images, we then revisited the redshift value provided in R21 by cross-correlating and/or reanalyzing the MUSE spectra, extracted within customized apertures following the shape of the distorted images.…”

“…The recent surge of high-quality photometric and spectroscopic data on galaxy clusters has made for some important progress in cluster lens models and their subsequent applications. In particular, the combination of high-resolution, panchromatic, and deep imaging data from the Hubble Space Telescope (Hubble) with follow-up spectroscopy with the Multi-Unit Spectroscopic Explorer (MUSE, Bacon et al 2012) on the Very Large Telescope (VLT) has lead to a significant increase in the number of multiple images securely identified in the core of galaxy clusters (see, e.g., Grillo et al 2016;Karman et al 2017;Lagattuta et al 2017;Bergamini et al 2023;Richard et al 2021, hereafter R21).…”

“…We identified 55 additional spectroscopically confirmed multiple images, an increase of ∼ 30% compared to the previous catalog published in B21. The new set of multiple images mainly consists of multiply-lensed clumps within resolved extended sources, which are particularly useful to constrain locally the position of the critical lines (as shown in Grillo et al 2016;Bergamini et al 2021Bergamini et al , 2023. The final multiple-image sample consists of 237 multiple images from 88 different background sources, spanning a wide redshift range z = 0.94 -6.63 (see Fig.…”

A massive interacting galaxy 525 million years after the Big Bang

“…The NIRSpec data we use are part of the GLASS-JWST program ERS-1324 [37] centered on the foreground galaxy cluster Abell 2744, which is gravitationally lensing the high-redshift background sources. Gz9p3 is located in the outskirts of the cluster and relatively far away from high-magnification regions, with a best estimate of the lensing magnification µ = 1.658 +0.016 −0.015 based on [38] (see 2.3).…”