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

Abstract

We present Hubble Space Telescope images and 2 years of optical photometry of the quadruple quasar HE 0435-1223. The time delays between the intrinsic quasar variations are ΔtAD = -14.37, ΔtAB = -8.00, and ΔtAC = -2.10 days. We also observed nonintrinsic variations of ~0.1 mag yr-1 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-1 Mpc-1 and derive constraints on the rotation curve. On the scale over which the lensed images occur (12 = 5 h-1 kpc 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.