Reducing the impact of weaklensing errors on gravitationalwave standard sirens
Abstract
The mergers of supermassive black hole binaries can serve as standard sirens: the gravitationalwave (GW) analogue 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 ultradeepfield 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 weaklensing surveys and/or the methods to reconstruct convergence maps from these surveys.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 July 2023
 DOI:
 10.1093/mnras/stad1194
 arXiv:
 arXiv:2211.15160
 Bibcode:
 2023MNRAS.522.4059W
 Keywords:

 gravitational lensing: weak;
 gravitational waves;
 cosmological parameters;
 distance scale;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 20 pages, 22 figures, to be published in MNRAS