Reducing the impact of weak-lensing errors on gravitational-wave standard sirens

Wu, Z.-F., Chan, L. W.L., Hendry, M. and Hannuksela, O. A. (2023) Reducing the impact of weak-lensing errors on gravitational-wave standard sirens. Monthly Notices of the Royal Astronomical Society, 522(3), pp. 4059-4077. (doi: 10.1093/mnras/stad1194)

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Abstract

The mergers of supermassive black hole binaries can serve as standard sirens: the gravitational-wave (GW) analogue of standard candles. The upcoming space-borne GW detectors will be able to discover such systems and estimate their luminosity distances precisely. Unfortunately, weak gravitational lensing can induce significant errors in the measured distance of these standard sirens at high redshift, severely limiting their usefulness as precise distance probes. The uncertainty due to weak lensing can be reduced if the lensing magnification of the siren can be estimated independently, a procedure called ‘delensing’. With the help of up-to-date numerical simulations, here we investigate how much the weak-lensing errors can be reduced using convergence maps reconstructed from shear measurements. We also evaluate the impact of delensing on cosmological parameter estimation with bright standard sirens. We find that the weak-lensing errors for sirens at zs = 2.9 can be reduced by about a factor of two on average, but to achieve this would require expensive ultra-deep-field observations for every siren. Such an approach is likely to be practical in only limited cases, and the reduction in the weak-lensing error is therefore likely to be insufficient to significantly improve the cosmological parameter estimation. We conclude that performing delensing corrections is unlikely to be worthwhile, in contrast to the more positive expectations presented in previous studies. For delensing to become more practicable and useful in the future will require significant improvements in the resolution/depth of weak-lensing surveys and/or the methods to reconstruct convergence maps from these surveys.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Hendry, Professor Martin
Authors: Wu, Z.-F., Chan, L. W.L., Hendry, M., and Hannuksela, O. A.
College/School:College of Science and Engineering > School of Physics and Astronomy
Research Centre:College of Science and Engineering > School of Physics and Astronomy > Institute for Gravitational Research
Journal Name:Monthly Notices of the Royal Astronomical Society
Publisher:Oxford University Press
ISSN:0035-8711
ISSN (Online):1365-2966
Published Online:05 May 2023
Copyright Holders:Copyright © 2023 The Authors
First Published:First published in Monthly Notices of the Royal Astronomical Society 522(3): 4059-4077
Publisher Policy:Reproduced with the permission of the Publisher
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
169451Investigations in Gravitational RadiationSheila RowanScience and Technology Facilities Council (STFC)ST/L000946/1P&S - Physics & Astronomy