TDCOSMO XXX: Spatially resolved kinematics of the deflectors in time-delay lens systems B1608+656 and SDSSJ1206+4332 from JWST-NIRSpec observation

@misc{mozumdar2026tdcosmo,
  title = {{TDCOSMO XXX: Spatially resolved kinematics of the deflectors in time-delay lens systems B1608+656 and SDSSJ1206+4332 from JWST-NIRSpec observation}},
  author = {Pritom Mozumdar and Shawn Knabel and Anowar J. Shajib and Tommaso Treu and Michele Cappellari and Aymeric Galan},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.09411},
  eprint = {2609.09411},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.09411},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - TDCOSMO XXX: Spatially resolved kinematics of the deflectors in time-delay lens systems B1608+656 and SDSSJ1206+4332 from JWST-NIRSpec observation
AU  - Pritom Mozumdar
AU  - Shawn Knabel
AU  - Anowar J. Shajib
AU  - Tommaso Treu
AU  - Michele Cappellari
AU  - Aymeric Galan
PY  - 2026
DA  - 2026/09/08
PB  - arXiv
DO  - 10.48550/arxiv.2609.09411
UR  - https://arxiv.org/abs/2609.09411
AB  - We present spatially resolved stellar kinematics of the deflector galaxies in two time-delay lens systems, B1608+656 and SDSS J1206+4332, measured from JWST NIRSpec integral field spectroscopy. B1608+656 is a quadruply imaged quasar lensed by a pair of tidally interacting galaxies, the primary deflector (G1) and a close companion (G2), for which we quantified G2's tidal influence on G1 and define a criterion identifying the region where this perturbation is negligible and standard Jeans-equation modeling remains valid. SDSS J1206+4332 is a doubly imaged quasar whose extended host galaxy is itself quadruply imaged by a foreground massive galaxy (G0), accompanied by a fainter perturber (G1). For both systems, we report the first spectroscopic redshift and velocity dispersion measurements of the perturber galaxies. For G2 in B1608+656, we measure σ_v = 188 +/- 7 (stat.) +/- 2 (sys.) km/s at z = 0.6307, identical to the redshift of the main deflector G1. For G1 in SDSS J1206+4332, we find σ_v = 100 +/- 21 (stat.) +/- 2 (sys.) km/s at z = 0.7403, slightly lower than the primary deflector G0. The resolved velocity maps of both primary deflectors show clear rotation signatures and we visually classify them as fast or regular rotators. The data products will be made publicly available and will be combined with time delays, lens models, and line-of-sight convergence to measure cosmological parameters in the upcoming TDCOSMO 2026 milestone publication.
ER  -