The Halos of Satellite Galaxies: the Companion of the Massive Elliptical Lens SL2S J08544-0121
Sherry H. Suyu, Aleksi Halkola

TL;DR
This paper uses strong gravitational lensing to measure the dark matter halo size of a satellite galaxy in a group, revealing tidal stripping effects and alignment properties of the mass distribution.
Contribution
First measurement of an individual galaxy halo size in a group via strong lensing without assuming mass follows light, demonstrating tidal stripping effects.
Findings
Halo size measured as 6.0^{+2.9}_{-2.0} kpc
Halo size consistent with tidal radius, indicating tidal stripping
Mass distribution aligned more towards the host halo center
Abstract
Strong gravitational lensing by groups or clusters of galaxies provides a powerful technique to measure the dark matter properties of individual lens galaxies. We study in detail the mass distribution of the satellite lens galaxy in the group-scale lens SL2S J08544-0121 by modelling simultaneously the spatially extended surface brightness distribution of the source galaxy and the lens mass distribution using Markov chain Monte Carlo methods. In particular, we measure the dark matter halo size of the satellite lens galaxy to be 6.0^{+2.9}_{-2.0} kpc with a fiducial velocity dispersion of 127^{+21}_{-12} km/s. This is the first time the size of an individual galaxy halo in a galaxy group has been measured using strong gravitational lensing without assumptions of mass following light. We verify the robustness of our halo size measurement using mock data resembling our lens system. Our…
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