A steady-tone search finds no excess from 40 to 500 Hz at 2 to 18 seconds after GW150914

We test public H1 and L1 strain for a steady 16-second tone from 2 to 18 seconds after GW150914. The search covers 40 to 500 Hz. Minimum normalized detector power gives full-search ranks of 0.619 and 0.889 with early and late noise estimates. No tone passes the chosen empirical threshold. Separate calibration and held-out controls test false alarms and injected-signal recovery. Drifting signals and unequal detector amplitudes are also tested. The Livingston record has a continuous-wave hardware-injection flag. Small tail samples, noise drift, lines, fixed duration and the lack of a phase test limit the result. We find no new source and set no astrophysical upper limit. Code, source hashes, aggregate spectra, recovery results, a figure and retrieval steps are included. Raw strain stays external.

astronomy · GW150914 · steady tones · gravitational waves · null result · signal recovery