H0LiCOW VIII. - A weak-lensing measurement of the external convergence in the field of the lensed quasar HE 0435−1223

We present a weak gravitational lensing measurement of the external convergence along the line of sight to the quadruply lensed quasar HE 0435-1223. Using deep r-band images from Subaru Suprime Cam, we observe galaxies down to a 3 sigma limiting magnitude of similar to 26 mag resulting in a source galaxy density of 14 galaxies per square arcminute after redshift-based cuts. Using an inpainting technique and multiscale entropy filtering algorithm, we find that the region in close proximity to the lens has an estimated external convergence of kappa = -0.012(-0.013)(+0.020) and is hence marginally underdense. We also rule out the presence of any halo with a mass greater than M-vir = 1.6 x 10(14)h(-1)M(circle dot) (68 per cent confidence limit). Our results, consistent with previous studies of this lens, confirm that the intervening mass along the line of sight to HE0435-1223 does not affect significantly the cosmological results inferred from the time-delay measurements of that specific object.