The Time Delays of Gravitational Lens HE 0435−1223: An Early‐Type Galaxy with a Rising Rotation Curve

We present Hubble Space Telescope images and 2 years of optical photometry of the quadruple quasar HE0435-1223. The time delays between the intrinsic quasar variations are 14. 4+/-0. 8 (A-D), 8. 0+/-0. 8 (A-B) and 2. 1+/-0. 8 (A-C) days. We also observed non-intrinsic variations of ~0. 1 mag/yr that we attribute to microlensing. Instead of the traditional approach of assuming a rotation curve for the lens galaxy and then deriving the Hubble constant (H₀), we assume H₀= (72+/-7) km/s/Mpc and derive constraints on the rotation curve. On the scale over which the lensed images occur (1. 2"=5kpc/h=1. 5Rₑ), the lens galaxy must have a rising rotation curve, and it cannot have a constant mass-to-light ratio. These results add to the evidence that the structures of early-type galaxies are heterogeneous.