Missing Lensed Images and the Galaxy Disk Mass in CXOCY J220132.8-320144

TL;DR

This study uses HST observations to analyze the mass distribution of the lensing galaxy in CXOCY J220132.8-320144, finding no extra images but constraining models and predicting future JWST detections to refine disk mass estimates.

Contribution

The paper provides new constraints on the galaxy's mass distribution and dust extinction effects, highlighting the potential of JWST to detect hidden images and improve mass measurements.

Findings

No additional images detected with HST.

Models require 2 magnitudes of dust extinction.

Future JWST observations could detect hidden images.

Abstract

The CXOCY J220132.8-320144 system consists of an edge-on spiral galaxy lensing a background quasar into two bright images. Previous efforts to constrain the mass distribution in the galaxy have suggested that at least one additional image must be present (Castander et al. 2006). These extra images may be hidden behind the disk which features a prominent dust lane. We present and analyze Hubble Space Telescope (HST) observations of the system. We do not detect any extra images, but the observations further narrow the observable parameters of the lens system. We explore a range of models to describe the mass distribution in the system and find that a variety of acceptable model fits exist. All plausible models require 2 magnitudes of dust extinction in order to obscure extra images from detection, and some models may require an offset between the center of the galaxy and the center of the dark matter halo of 1 kiloparsec. Currently unobserved images will be detectable by future James Webb Space Telescope (JWST) observations and will provide strict constraints on the fraction of mass in the disk.