Kavli Affiliate: Joshua A. Frieman
| First 5 Authors: Anowar J. Shajib, Tommaso Treu, Sherry H. Suyu, David Law, Akın Yıldırım
| Summary:
Spatially resolved stellar kinematics has become a key ingredient in
time-delay cosmography to break the mass-sheet degeneracy in the mass profile
and, in turn, provide a precise constraint on the Hubble constant and other
cosmological parameters. In this paper, we present the first measurements of 2D
resolved stellar kinematics for the lens galaxy in the quadruply lensed quasar
system lensname, using integral field spectroscopy from the JWST’s
Near-Infrared Spectrograph (NIRSpec), marking the first such measurement
conducted with the JWST. In extracting robust kinematic measurements from this
first-of-its-kind dataset, we made methodological improvements both in the data
reduction and kinematic extraction. In our kinematic extraction procedure, we
performed joint modeling of the lens galaxy, the quasar, and its host galaxy’s
contributions in the spectra to deblend the lens galaxy component and robustly
constrain its stellar kinematics. Our improved methodological frameworks are
released as software pipelines for future use: textsc{squirrel} for extracting
stellar kinematics, and textsc{RegalJumper} for JWST-NIRSpec data reduction,
incorporating additional artifact cleaning beyond the standard JWST pipeline.
We compared our measured stellar kinematics from the JWST NIRSpec with
previously obtained ground-based measurements from the Keck Cosmic Web Imager
integral field unit and find that the two datasets are statistically consistent
at a $sim$1.1$sigma$ confidence level. Our measured kinematics will be used
in a future study to improve the precision of the Hubble constant measurement.
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