Reducing the Impact of Weaklensing Errors on Gravitationalwave Standard Sirens
Abstract
The mergers of supermassive black hole binaries (SMBHBs) can serve as standard sirens: the gravitational wave (GW) analog of standard candles. The upcoming spaceborne 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 uptodate numerical simulations, here we investigate how much the weaklensing 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 weaklensing errors for sirens at $z_s = 2.9$ can be reduced by about a factor of two on average, but to achieve this would require expensive ultradeep field observations for every siren. Such an approach is likely to be practical in only limited cases, and the reduction in the weaklensing 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 the weaklensing surveys themselves and/or the accuracy of the methods to reconstruct convergence maps from these surveys.
 Publication:

arXiv eprints
 Pub Date:
 November 2022
 DOI:
 10.48550/arXiv.2211.15160
 arXiv:
 arXiv:2211.15160
 Bibcode:
 2022arXiv221115160W
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 19 pages, 22 figures, submitted to MNRAS