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 HE0435-1223. Using deep r-band images from Subaru-Suprime-Cam we observe galaxies down to a 3 sigmas limiting magnitude of ~26 mags resulting in a source galaxy density of 14 galaxies per square arcmin after redshift-based cuts. Using an inpainting technique and Multi-Scale Entropy filtering algorithm, we find that the region in close proximity to the lens has an estimated external convergence of κ_ext = -0.012 ^+0.020_-0.013 and is hence marginally under-dense. We also rule out the presence of any halo with a mass greater than M_vir=1.6 x 10¹⁴ 1/h M_Sol (68% 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.