The Carousel Lens III: Joint lens convergence and source kinematic modeling
Abstract
We introduce a new, independent modeling component to the Carousel Lens series by exploiting the spatially-resolved kinematics contained within the lensed arcs, which so far has remained rather underexplored in strong-lensing analyses. We present an end-to-end forward-modeling framework that reconstructs an integral-field spectroscopic datacube from a parameterization of the lens convergence profile together with the line-of-sight velocity, velocity dispersion, and surface brightness profiles of the unlensed source. The kinematic structure of the source acts as an additional set of ray-traceable markers distributed across every lensed image, inaccessible from imaging data alone. Furthermore, by generating an [OII] emission-line datacube, we isolate a single source redshift and remove lens and line-of-sight light contamination. We apply this framework to deep VLT/MUSE observations of the Carousel Lens, modeling the [OII] emission of the quadruply-imaged star-forming galaxy at zs = 1.432 that anchors the system's cosmography constraints. We measure an Einstein radius θE = 12.816''+0.005−0.007 and a logarithmic slope γ= 1.412+0.002−0.002, tightening the statistical uncertainties on both by roughly a factor of 2−2.5 relative to the corresponding flat emission-line map model. We find that the source galaxy exhibits a strong rotation, lies confidently along the star-forming main sequence, and has an inferred central black hole mass of log MBH/M⊙ = 7.89 ± 0.51. These results establish datacube-level forward modeling as a practical and independent route to traditional image-based lens models in the current systematics-limited regime, and one that extends naturally to this system's other lensed sources and to other lens systems.
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BibTeX
@misc{sheu2026carousel,
title = {{The Carousel Lens III: Joint lens convergence and source kinematic modeling}},
author = {William Sheu and Xiaosheng Huang and Tania M. Barone and Fuyan Bian and Aleksandar Cikota and Karl Glazebrook and Tesla Jeltema and Evan Odell and Jackson H. O'Donnell and Linus Upson and Felipe Urcelay and Sean Xu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.37971},
eprint = {2610.37971},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.37971},
}
RIS
TY - UNPB
TI - The Carousel Lens III: Joint lens convergence and source kinematic modeling
AU - William Sheu
AU - Xiaosheng Huang
AU - Tania M. Barone
AU - Fuyan Bian
AU - Aleksandar Cikota
AU - Karl Glazebrook
AU - Tesla Jeltema
AU - Evan Odell
AU - Jackson H. O'Donnell
AU - Linus Upson
AU - Felipe Urcelay
AU - Sean Xu
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.37971
UR - https://arxiv.org/abs/2610.37971
AB - We introduce a new, independent modeling component to the Carousel Lens series by exploiting the spatially-resolved kinematics contained within the lensed arcs, which so far has remained rather underexplored in strong-lensing analyses. We present an end-to-end forward-modeling framework that reconstructs an integral-field spectroscopic datacube from a parameterization of the lens convergence profile together with the line-of-sight velocity, velocity dispersion, and surface brightness profiles of the unlensed source. The kinematic structure of the source acts as an additional set of ray-traceable markers distributed across every lensed image, inaccessible from imaging data alone. Furthermore, by generating an [OII] emission-line datacube, we isolate a single source redshift and remove lens and line-of-sight light contamination. We apply this framework to deep VLT/MUSE observations of the Carousel Lens, modeling the [OII] emission of the quadruply-imaged star-forming galaxy at z_s = 1.432 that anchors the system's cosmography constraints. We measure an Einstein radius θ_E = 12.816''^+0.005_−0.007 and a logarithmic slope γ= 1.412^+0.002_−0.002, tightening the statistical uncertainties on both by roughly a factor of 2−2.5 relative to the corresponding flat emission-line map model. We find that the source galaxy exhibits a strong rotation, lies confidently along the star-forming main sequence, and has an inferred central black hole mass of log M_BH/M_⊙ = 7.89 ± 0.51. These results establish datacube-level forward modeling as a practical and independent route to traditional image-based lens models in the current systematics-limited regime, and one that extends naturally to this system's other lensed sources and to other lens systems.
ER -