The Mass Distribution of SDSS J1004+4112 Revisited

TL;DR

This paper revisits the mass distribution of the SDSS J1004+4112 quasar lens using advanced gravitational lensing software, confirming a relaxed cluster with a high magnification and consistent mass profile with X-ray data.

Contribution

It introduces a new parametric lensing model that accurately reproduces observations and provides insights into the cluster's mass distribution and structure.

Findings

Mass model reproduces all observed image positions and time delays.

Predicted magnification of about 70 enhances quasar studies.

Mass profile aligns with X-ray observations and suggests a relaxed cluster.

Abstract

We present a strong lens analysis of SDSS J1004+4112, a unique quasar lens produced by a massive cluster of galaxies at z=0.68, using a newly developed software for gravitational lensing. We find that our parametric mass model well reproduces all observations including the positions of quasar images as well as those of multiply imaged galaxies with measured spectroscopic redshifts, time delays between quasar images, and the positions of faint central images. The predicted large total magnification of \mu ~ 70 suggests that the lens system is indeed a useful site for studying the fine structure of a distant quasar and its host galaxy. The dark halo component is found to be unimodal centered on the brightest cluster galaxy and the Chandra X-ray surface brightness profile. In addition, the orientation of the halo component is quite consistent with those of the brightest cluster galaxy and member galaxy distribution, implying that the lensing cluster is a relaxed system. The radial profile of the best-fit mass model is in good agreement with a mass profile inferred from the X-ray observation. While the inner radial slope of the dark halo component is consistent with being -1, a clear dependence of the predicted A-D time delay on the slope indicates that an additional time delay measurement will improve constraints on the mass model.