The geometry of the quadruply imaged quasar PG 1115+080; implications for Ho

TL;DR

This paper uses advanced deconvolution techniques on high-resolution images of the quadruply imaged quasar PG 1115+080 to improve the lensing model, enabling a more precise estimate of the Hubble constant.

Contribution

It introduces a novel application of deconvolution to refine lensing potential constraints, leading to a more accurate determination of Ho.

Findings

Refined the lensing galaxy position by a factor of 3

Derived a Hubble constant estimate of 53 (+10/-7) km/s/mpc

Enhanced constraints on the lensing potential through improved imaging data

Abstract

Time delay measurements have recently been reported for the lensed quasar PG 1115+080. These measurements can be used to derive Ho, but only if we can constrain the lensing potential. We have applied a recently developed deconvolution technique to analyse sub-arcsecond I band images of PG 1115+080, obtained at the Nordic Optical Telescope (NOT) and the Canada France Hawaii Telescope (CFHT). The high performance of the deconvolution code allows us to derive precise positions and magnitudes for the four lensed images of the quasar, as well as for the lensing galaxy. The new measurement of the galaxy position improves its precision by a factor of 3 and thus strengthens the constraints on the lensing potential. With the new data, a range of models incorporating some of the plausible systematic uncertainties yields Ho = 53 (+10/-7) km/s/mpc.