Wednesday

I present early results from a kinematic modelling analysis of the unique J0946+1006 (‘Jackpot’) triple-source lens system, noted for previous detections of the presence of a dark substructure. Deep IFU spectroscopic data were obtained using the MUSE instrument on the VLT which, compared to previous single-slit observations, provides full azimuthal area coverage, high sensitivity (5hr integration) and high angular resolution (0.5" FWHM). As a result we can measure the two-dimensional stellar kinematic properties out to ~10 kpc, as well as resolving the inner profile inwards to ~1 kpc. We have implemented template-spectra fitting methods to fit the kinematics of both the z=0.222 lens galaxy and the z=0.609 bright arc background source. I will show early results from analysing the kinematics using JAM dynamical models to constrain the slope of the total mass density profile. Our results will help test the surprising recent claim of a very compact dark substructure by breaking the degeneracy between the properties of the dark substructure and the overall density profile slope in the lensing analyses.