Mass density slope of elliptical galaxies from strong lensing and resolved stellar kinematics

Understand

We discuss constraints on the mass density distribution (parameterized as $\rho\propto r^{-\gamma}$) in early-type galaxies provided by strong lensing and stellar kinematics data.

• The constraints come from mass measurements at two `pinch' radii.
• One `pinch' radius $r_1=2.2 R_{Einst}$ is defined such that the Einstein (i.e.
• aperture) mass can be converted to the spherical mass almost independently of the mass-model.