We study the Sloan Lens ACS survey ( SLACS ) strong lensing system SDSS J1430+4105 at z _ { l } = 0.285 .
The lensed source ( z _ { s } = 0.575 ) of this system has a complex morphology with several subcomponents .
Its subcomponents span a radial range from 4 kpc to 10 kpc in the plane of the lens .
Therefore we can constrain the slope of the total projected mass profile around the Einstein radius from lensing alone .
We measure a density profile that is slightly but not significantly shallower than isothermal at the Einstein radius .
We decompose the mass of the lensing galaxy into a de Vaucouleurs component to trace the stars and an additional dark component .
The spread of multiple image components over a large radial range also allows us to determine the amplitude of the de Vaucouleurs and dark matter components separately .
We get a mass to light ratio of \frac { M _ { deVauc } } { L _ { B } } \approx ( 5.5 \pm 1.5 ) \frac { M _ { \odot } } { % L _ { \odot, B } } and a dark matter fraction within the Einstein radius of \approx 20 \% to 40 \% .
Modelling the star formation history assuming composite stellar populations at solar metallicity to the galaxy ’ s photometry yields a mass to light ratio of \frac { M _ { \star, salp } } { L _ { B } } \approx 4.0 _ { -1.3 } ^ { +0.6 } \frac { % M _ { \odot } } { L _ { \odot, B } } and \frac { M _ { \star, chab } } { L _ { B } } \approx 2.3 _ { -0.8 } ^ { +0.3 } \frac { % M _ { \odot } } { L _ { \odot, B } } for Salpeter and Chabrier IMFs , respectively .
Hence , the mass to light ratio derived from lensing is more Salpeter-like , in agreement with results for massive Coma galaxies and other nearby massive early type galaxies .
We examine the consequences of the galaxy group in which the lensing galaxy is embedded , showing that it has little influence on the mass to light ratio obtained for the de Vaucouleurs component of the lensing galaxy .
Finally , we decompose the projected , azimuthally averaged 2D density distribution of the de Vaucouleurs and dark matter component of the lensing signal into spherically averaged 3D density profiles .
We can show that the 3D dark and luminous matter density within the Einstein radius ( R _ { Ein } \approx 0.6 R _ { eff } ) of this SLACS galaxy is similar to the values of Coma galaxies with the same velocity dispersions .