Bright sirens break H0-Omega_m degeneracy despite falling NS merger rates, arXiv:2609.12053 finds
Unified statistical treatment of bright and dark sirens shows bright events are still required to break cosmological parameter degeneracies even at reduced rates. Separate population modeling does not bias H0 in the near term but affects mass-spectrum recovery.
LVK O4 data lowered neutron-star merger rate estimates, reducing expected bright-siren detections. The authors model a unified population of black holes and neutron stars and demonstrate that bright events supply the electromagnetic redshift anchor needed to separate H0 from Omega_m. Dark sirens alone recover H0 only when an external Omega_m prior is imposed. Treating the two classes as independent populations produces negligible bias in H0 for the next two LVK runs yet distorts the low-mass end of the mass spectrum. A joint hierarchical likelihood that shares the underlying mass distribution removes this distortion while preserving cosmological constraints.
LVK: Joint bright-dark analysis yields <1% H0 bias through O5 when mass distribution is shared
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2609.12053)
- [2]Supporting Source(https://arxiv.org/abs/2308.14787)