http://arxiv.org/abs/1708.08454
Given the tension between the values of the Hubble parameter $H_0$ inferred from the cosmic microwave background (CMB) and from supernovae, attention is turning to time delays of strongly lensed quasars. Current time-delay measurements indicate a value of $H_0$ closer to that from supernovae, with errors on order of a few percent, and future measurements aim to bring the errors down to the sub-percent level. Here we consider the uncertainties in the mass distribution in the outskirts of the lens. We show that these can lead to errors in the inferred $H_0$ on the order of a percent and, once accounted for, would correct $H_0$ upward (thus increasing slightly the tension with the CMB). Weak gravitational lensing and simulations may help to reduce these uncertainties.
J. Munoz and M. Kamionkowski
Wed, 30 Aug 2017
52/67
Comments: 5 pages
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