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 aretAD ¼� 14:37 þ0:75 � 0:85 , � tAB ¼� 8:00 þ0:73 � 0:82 ,a nd � tAC ¼� 2:10 þ0:78 � 0:71 days. We also observed nonintrinsic variations of � 0.1 mag yr� 1 that we attribute to micro- lensing. Instead of the traditional approach of assuming a rotation curve for the lens galaxy and then deriving the Hubbleconstant(H0),we assumeH0 ¼ (72 � 7) km s� 1Mpc� 1andderiveconstraintsontherotationcurve.Onthe scale over which the lensed images occur (1B2 ¼ 5 h � 1 kpc ' 1:5Re), the lens galaxy must have a rising rotation curve,anditcannothaveaconstantmass-to-lightratio.Theseresultsaddtotheevidencethatthestructuresofearly- type galaxies are heterogeneous. Subject headingg cosmological parameters — dark matter — galaxies: kinematics and dynamics — gravitational lensing — quasars: individual (HE 0435� 1223)