Dark and stellar matter in strong lensing galaxies from a joint lensing and stellar dynamics

TL;DR

This study combines lensing and stellar dynamics to analyze the mass distribution of two strong lensing galaxies, finding that one fits an isothermal profile while the other suggests additional mass contributions from surrounding structures.

Contribution

It provides the first joint lensing and stellar dynamics analysis of these galaxies, revealing their mass profiles and the influence of environment on lensing properties.

Findings

HST14113+5211's mass profile is consistent with a singular isothermal sphere.

B2045+265's mass profile is flatter than isothermal, indicating environmental effects.

Mass-to-light ratios align with the Fundamental Plane estimates.

Abstract

We present Subaru spectroscopy of the early-type lensing galaxies in the lens systems HST14113+5211 (z=0.464) and B2045+265 (z=0.868), being aimed at measuring the velocity dispersion of the lensing galaxies as an important component to their mass distributions and internal dynamics. For HST14113+5211 we have obtained 174+/-20km/s (1-sigma) inside an aperture of 0.9", and for B2045+265 we have obtained 213+/-23km/s inside an aperture of 1.2". To extract the significance of these information on the mass distributions and stellar dynamics of the lensing galaxies, we construct two alternative models for both the mass and velocity distributions. It is found that the mass-to-light ratios as derived from a joint lensing and stellar dynamics analysis are virtually consistent with those obtained from the use of the Fundamental Plane. Also, for HST14113+5211, we find that the total mass distribution is well reproduced by a power-law density profile with an index of 2, thereby suggesting that a singular isothermal model is a good fit to the lensing galaxy. In contrast, the corresponding slope for B2045+265 is flatter than isothermal, suggesting that additional contributions to lensing mass from surrounding structures (possibly the group of galaxies) provide the observed angular separations of multiple images.