Gravitational Wave 'Spectral Siren' Technique Faces Hubble Constant Measurement Challenges

The blinded mock data challenge analysis presented in this paper reveals critical challenges in using the spectral siren technique for measuring the Hubble constant. The study demonstrates that the accuracy of the technique is highly sensitive to assumptions about the mass distribution of binary black holes (BBHs) across cosmic redshifts. Specifically, the metallicity dependence of the BBH mass distribution and its interplay with time-delay distribution are crucial factors that must be accurately captured to ensure a robust inference of the Hubble constant. A mismatch between the true model and the underlying assumptions made in the analysis can lead to a best-fit model for the wrong value of both BBH population parameters and the Hubble constant. This finding highlights the importance of independently inferring the mass distribution of BBHs at all relevant redshifts with an accuracy less than the statistical uncertainty. Otherwise, the spectral siren technique may not be able to provide a reliable measurement of the Hubble constant at the level required to resolve the Hubble tension. Future research efforts should focus on developing methods for accurately characterizing the BBH mass distribution and mitigating the potential biases in the spectral siren technique.

_Context: This intelligence report was compiled by the DailyOrbitalWire Strategy Engine. Verified for Art. 50 Compliance._