2017MNRAS.465.4914B

We present a new measurement of the Hubble Constant H₀ and other cosmological parameters based on the joint analysis of three multiply imaged quasar systems with measured gravitational time delays. First, we measure the time delay of HE 0435-1223 from 13-yr light curves obtained as part of the COSMOGRAIL project. Companion papers detail the modelling of the main deflectors and line-of-sight effects, and how these data are combined to determine the time-delay distance of HE 0435-1223. Crucially, the measurements are carried out blindly with respect to cosmological parameters in order to avoid confirmation bias. We then combine the time-delay distance of HE 0435-1223 with previous measurements from systems B1608+656 and RXJ1131-1231 to create a Time Delay Strong Lensing probe (TDSL). In flat Λ cold dark matter (ΛCDM) with free matter and energy density, we find H₀ =71.9^+2.4_–3.0 km/s/Mpc and Ω_Λ =0.62^+0.24_–0.35. This measurement is completely independent of, and in agreement with, the local distance ladder measurements of H₀. We explore more general cosmological models combining TDSL with other probes, illustrating its power to break degeneracies inherent to other methods. The joint constraints from TDSL and Planck are H₀ = 69.2_–2.2^+1.4 km/s/Mpc, Ω_Λ =0.70_–0.01^+0.01 and Ω_k=0.003_–0.006^+0.004 in open ΛCDM and H₀ =79.0_–4.2^+4.4 km/s/Mpc, Ω_de=0.77_–0.03^+0.02 and w=-1.38_–0.16^+0.14 in flat wCDM. In combination with Planck and baryon acoustic oscillation data, when relaxing the constraints on the numbers of relativistic species we find N_eff = 3.34_–0.21^+0.21 in N_effΛ CDM and when relaxing the total mass of neutrinos we find Σm_ν <= 0.182 eV in m_νΛCDM. Finally, in an open wCDM in combination with Planck and cosmic microwave background lensing, we find H₀ =77.9_–4.2^+5.0 km/s/Mpc, Ω_de=0.77_–0.03^+0.03, Ω_k=-0.003_–0.004^+0.004 and w=-1.37_–0.23^+0.18.