Resolving 3 Exotic Hyperbolic-Umbilic Lensing Configurations in the "Cosmic Mantis": An Exploration of RXJ0437.1+0043 with JWST

@misc{cerny2026resolving,
  title = {{Resolving 3 Exotic Hyperbolic-Umbilic Lensing Configurations in the "Cosmic Mantis": An Exploration of RXJ0437.1+0043 with JWST}},
  author = {Catherine Cerny and David J. Lagattuta and Keren Sharon and Gourav Khullar and Benjamin Beauchesne and Alastair C. Edge and Mathilde Jauzac and Marceau Limousin and Guillaume Mahler and Lukas J. Furtak and Leo Fung and Qiuhan He and Richard J. Massey and Ashish K. Meena and Adi Zitrin},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.17852},
  eprint = {2609.17852},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.17852},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Resolving 3 Exotic Hyperbolic-Umbilic Lensing Configurations in the "Cosmic Mantis": An Exploration of RXJ0437.1+0043 with JWST
AU  - Catherine Cerny
AU  - David J. Lagattuta
AU  - Keren Sharon
AU  - Gourav Khullar
AU  - Benjamin Beauchesne
AU  - Alastair C. Edge
AU  - Mathilde Jauzac
AU  - Marceau Limousin
AU  - Guillaume Mahler
AU  - Lukas J. Furtak
AU  - Leo Fung
AU  - Qiuhan He
AU  - Richard J. Massey
AU  - Ashish K. Meena
AU  - Adi Zitrin
PY  - 2026
DA  - 2026/09/15
PB  - arXiv
DO  - 10.48550/arxiv.2609.17852
UR  - https://arxiv.org/abs/2609.17852
AB  - We present an updated strong lensing model for the galaxy cluster RXJ0437.1+0043 (z=0.285) using new JWST NIRCam imaging in four pass-bands. The cluster field notably displays at least three separate gravitationally lensed galaxies in hyperbolic-umbilic (H-U) configurations, which in the JWST imaging show exquisitely resolved stellar clumps at scales as small as 0.04''. We identify 13 new systems of multiply-imaged lensed galaxies and determine the redshifts for two sources based on archival spectroscopic observations. We also identify over 50 individually resolved substructure clumps in the multiple images of eight galaxies and add them into the lens model, for a total of 275 positional lensing constraints between all 26 lensed sources used in the model. We investigate the impact of different modeling choices on our results. In the final lens model, we reproduce the observed multiple images with a precision of 0.23'' , and achieve 0.13'' specifically for the H-U systems. We estimate a total enclosed mass in the cluster's strong lensing regime of M(<110 kpc) ~ 8.2 x 10^13 Msun, reconstruct the source images of the most highly magnified galaxies, and measure time delays in the most magnified, morphologically detailed systems. The isotropic lensing effect from the H-U configurations enables future detailed studies of the properties of their source galaxies, and the number and spatial density of additional constraints improve the model's ability to detect dark matter substructures within the cluster core.
ER  -