The impact of line-of-sight structures on measuring $H_0$ with strong lensing time-delays

Abstract

Measurements of The Hubble-Lemaitre constant from early- and local-universe observations show a significant discrepancy. In an attempt to understand the origin of this mismatch, independent techniques to measure H0 are required. One such technique, strong lensing time delays, is set to become a leading contender amongst the myriad methods due to forthcoming large strong lens samples. It is therefore critical to understand the systematic effects inherent in this method. In this paper, we quantify the influence of additional structures along the line-of-sight by adopting realistic light cones derived from the CosmoDC2 semi-analytical extra-galactic catalogue. Using multiple lens plane ray-tracing to create a set of simulated strong lensing systems, we have investigated the impact of line-of-sight structures on time-delay measurements and in turn, on the inferred value of H0. We have also tested the reliability of existing procedures for correcting for line-of-sight effects. We find that if the integrated contribution of the line-of-sight structures is close to a uniform mass sheet, the bias in H0 can be adequately corrected by including a constant external convergence ${\kappa }_{ext}$ in the lens model. However, for realistic line-of-sight structures comprising many galaxies at different redshifts, this simple correction overestimates the bias by an amount that depends linearly on the median external convergence. We, therefore, conclude that lens modelling must incorporate multiple lens planes to account for line-of-sight structures for accurate and precise inference of H0.

12 pages, 8 figures, accepted for publication in MNRAS

References in corpus (19)

• Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics Beyond LambdaCDM
• Tensions between the Early and the Late Universe
• A distance to the Large Magellanic Cloud that is precise to one per cent
• The Expansion of the Universe is Faster than Expected
• H0LiCOW V. New COSMOGRAIL time delays of HE0435-1223: $H_0$ to 3.8% precision from strong lensing in a flat $\Lambda$CDM model
• Dark Energy Survey Year 1 Results: Cosmological Constraints from Cluster Abundances and Weak Lensing
• STRIDES: a 3.9 per cent measurement of the Hubble constant from the strong lens system DES J0408-5354
• H0LiCOW IV. Lens mass model of HE 0435-1223 and blind measurement of its time-delay distance for cosmology
• Consistent Calibration of the Tip of the Red Giant Branch in the Large Magellanic Cloud on the Hubble Space Telescope Photometric System and a Re-determination of the Hubble Constant
• Measuring the Hubble constant with Type Ia supernovae as near-infrared standard candles
• Strong Lens Time Delay Challenge: II. Results of TDC1
• CosmoDC2: A Synthetic Sky Catalog for Dark Energy Science with LSST
• H0LiCOW III. Quantifying the effect of mass along the line of sight to the gravitational lens HE 0435-1223 through weighted galaxy counts
• The Masses and Shapes of Dark Matter Halos from Galaxy-Galaxy Lensing in the CFHTLS
• Microlensing Makes Lensed Quasar Time Delays Significantly Time Variable
• The BOSS Emission-Line Lens Survey. IV. : Smooth Lens Models for the BELLS GALLERY Sample
• Measurements of $H_0$ in modified gravity theories: The role of lensed quasars in the late-time Universe
• Reducing biases on $H_0$ measurements using strong lensing and galaxy dynamics: results from the EAGLE simulation
• Large-Distance Lens Uncertainties and Time-Delay Measurements of $H_0$

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• lenstronomy II: A gravitational lensing software ecosystem
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• Pixelated Reconstruction of Foreground Density and Background Surface Brightness in Gravitational Lensing Systems using Recurrent Inference Machines
• CURLING -- II. Improvement on the $H_0$ Inference from Pixelized Cluster Strong Lens Modeling
• The Impact of $\text{CLEAN}$ing on Strong Gravitational Lens Modelling
• Impact of Large-Scale Structure along Line-of-Sight on Time-Delay Cosmography
• Time delay measurements with Broken Power Law model
• SDSS-IV MaNGA: A Catalogue of Spectroscopically Detected Strong Galaxy-Galaxy Lens Candidates