Measureability and reconstruction of low-frequency lensing coefficients

Determine to what extent the coefficients of the low-frequency expansion of the gravitational-wave lensing amplification factor can be measured in realistic gravitational-wave observations and how accurately the underlying lens density profile can be reconstructed from those coefficients.

Background

The paper derives a low-frequency expansion of the gravitational-wave lensing amplification factor under the Born approximation and relates its coefficients to moments and power-law-tail parameters of the lens density profile. Although this establishes a model-independent framework for encoding density information in wave-optical lensing, the practical observability of those coefficients is not analyzed.

The unresolved issue is whether realistic gravitational-wave data can measure the relevant expansion coefficients with sufficient precision, and what accuracy of density-profile reconstruction can consequently be achieved. This concerns the translation of the formal expansion into an observational inference method.