Noise-background validation of additional quasinormal-mode detections

Conduct a noise-background study to exclude noise mimicking an additional quasinormal mode in standard QNMRF ringdown analyses, thereby enabling robust interpretation of the detection statistic across ringdown start times.

Background

The paper uses the QNMRF pipeline to compare ringdown mode hypotheses, including a fundamental {220} model and a {220, 221} model containing the first overtone. The authors evaluate a detection statistic as a function of ringdown start time, but caution that apparent support for an additional mode could arise from detector noise rather than a genuine quasinormal-mode contribution. They explicitly defer the required noise-background study, making this an unresolved methodological task for interpreting additional-mode evidence.

References

Robust interpretation requires a noise-background study to exclude noise mimicking an additional QNM, which we defer to future work.

— Accounting for detector calibration uncertainty in black-hole ringdown analysis  (2610.11052 - Nathan et al., 8 Oct 2026) in Footnote in Section 4.1, immediately following the discussion of the joint H1–L1 analysis and Fig. 250207_2det