Impact of weak lensing on bright standard siren analyses

Understand

Gravitational waves from binary mergers at cosmological distances will experience weak lensing by large scale structure.

• This causes a (de-)magnification, $\mu$, of the wave amplitude, and a degenerate modification to the inferred luminosity distance $d_L$.
• To address this the uncertainty on $d_L$ is increased according to the dispersion of the magnification distribution at the source redshift, $\sigma_\mu$.
• But this term is dependent on cosmological parameters that are being constrained by gravitational wave "standard sirens", such as the Hubble parameter $H_0$, and the matter density fraction $\Omega_m$.