Reducing the weak lensing noise for the gravitational wave Hubble diagram using the non-Gaussianity of the magnification distribution

TL;DR

This paper demonstrates that leveraging the non-Gaussian characteristics of lensing magnification distribution can significantly enhance the accuracy of gravitational wave-based cosmological distance measurements, reducing lensing noise effects.

Contribution

It introduces a method to improve distance estimates by exploiting the non-Gaussianity of lensing magnification, surpassing traditional Gaussian assumptions.

Findings

Improved distance accuracy by a factor of 2-3 using non-Gaussianity.

Provides a fitting formula for effective distance precision across redshifts.

Shows that non-Gaussian features can be harnessed to mitigate lensing noise.

Abstract

Gravitational wave sources are a promising cosmological standard candle because their intrinsic luminosities are determined by fundamental physics (and are insensitive to dust extinction). They are, however, affected by weak lensing magnification due to the gravitational lensing from structures along the line of sight. This lensing is a source of uncertainty in the distance determination, even in the limit of perfect standard candle measurements. It is commonly believed that the uncertainty in the distance to an ensemble of gravitational wave sources is limited by the standard deviation of the lensing magnification distribution divided by the square root of the number of sources. Here we show that by exploiting the non-Gaussian nature of the lensing magnification distribution, we can improve this distance determination, typically by a factor of 2--3; we provide a fitting formula for the effective distance accuracy as a function of redshift for sources where the lensing noise dominates.