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

TL;DR

This study measures the external convergence along the line of sight to a quadruply lensed quasar using weak gravitational lensing, finding it to be marginally under-dense and not significantly impacting cosmological inferences.

Contribution

It provides a novel weak lensing measurement of external convergence for HE0435-1223, using deep Subaru imaging and advanced inpainting techniques.

Findings

External convergence is marginally under-dense at rac{-0.012^{+0.020}_{-0.013}}

No halo with mass greater than 1.67^{14}h^{-1}M_\u00b7odot detected

Line of sight mass distribution does not significantly affect cosmological results

Abstract

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 $\sim 26$ mags resulting in a source galaxy density of 14 galaxies / arcmin$^2$ 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 $\kappa=-0.012^{+0.020}_{-0.013}$ and is hence marginally under-dense. We also rule out the presence of any halo with a mass greater than $M_{\rm vir}=1.6\times10^{14}h^{-1}M_\odot$ (68$\%$ confidence limit). Our results, consistent with previous studies of this lens, confirm that the intervening mass along the line of sight to HE$\,$0435$-$1223 does not affect significantly the cosmological results inferred from the time delay measurements of that specific object.