A Strong Gravitational Lensing Model of PSZ2 G118.46+39.32
Isaac Smith, Catherine Cerny, Keren Sharon, Guillaume Mahler, Gourav Khullar, Benjamin Beauchesne, The SLICE Collaboration
TL;DR
This study presents the first strong gravitational lensing model for PSZ2 G118.46+39.32 by combining JWST SLICE NIRCam imaging with HST data and Lenstool-based parametric modeling. The mass distribution is captured with two cluster-scale PIEMD/dPIE halos, two galaxy-scale halos, and 195 fixed member halos, constrained by 11 multiply-imaged systems (30 images, 60 clumps). The resulting mass map yields $M(<500\,\text{kpc})=(4.9\pm0.1)\times10^{14}\,M_{\odot}$, with subcluster masses $M_{\mathrm{West}}(<150\,\text{kpc})=(0.82\pm0.01)\times10^{14}\,M_{\odot}$ and $M_{\mathrm{East}}(<150\,\text{kpc})=(0.99\pm0.01)\times10^{14}\,M_{\odot}$, and an offset between X-ray gas and lensing centroids $<1.3^{\prime\prime}$, indicating a pre-merger configuration. The image-plane rms of $0.34^{\prime\prime}$ and alignment of the mass distribution with X-ray gas support a bimodal mass structure; spectroscopic redshifts in future work will tighten redshift priors and improve constraints.
Abstract
We present the first strong gravitational lensing model for the cluster PSZ2 G118.46+39.32 (z = 0.3967) using new NIRCam imaging from the Strong LensIng and Cluster Evolution (SLICE) JWST program. We leverage the broad coverage of the SLICE ultrawide JWST filters to identify new lensed galaxies, some of which are not visible in HST, to model the cluster's mass distribution. The model was constructed with a total of 11 multiply imaged systems, decomposed into 30 images with 60 clumps used as strong lensing constraints. PSZ2 G118.46+39.32 shows a clear bimodal structure, indicating that it may be undergoing a merger. The predicted mass distribution of the model aligns with the X-ray gas in the cluster, suggesting it is in a pre-merger state.