Analysis of Ringdown Overtones in GW150914

TL;DR

This study critically examines claims of overtone detection in GW150914's ringdown phase, finding no robust evidence for overtones and highlighting the influence of noise on such detections.

Contribution

The paper demonstrates that previous overtone claims are likely noise artifacts by analyzing data and injections, challenging the robustness of overtone detection in gravitational wave signals.

Findings

No evidence for overtones after the waveform peak.

Bayes factor does not support overtone presence near the peak.

Noise can artificially produce overtone-like signals in data.

Abstract

We analyze GW150914 post-merger data to understand if ringdown overtone detection claims are robust. We find no evidence in favor of an overtone in the data after the waveform peak. Around the peak, the Bayes factor does not indicate the presence of an overtone, while the support for a nonzero amplitude is sensitive to changes in the starting time much smaller than the overtone damping time. This suggests that claims of an overtone detection are noise-dominated. We perform GW150914-like injections in neighboring segments of the real detector noise, and we show that noise can indeed induce artificial evidence for an overtone.