The classes C2 and C3 are defined in the text. Left: Along with the primary search (C3) we also show the results (blue markers) and background (green curve) for an alternative search that treats events independently of their frequency evolution ( C 2 + C 3). The significance of GW150914 is greater than 5.1 σ and 4.6 σ for the binary coalescence and the generic transient searches, respectively.
The scales on the top give the significance of an event in Gaussian standard deviations based on the corresponding noise background. These histograms show the number of candidate events (orange markers) and the mean number of background events (black lines) in the search class where GW150914 was found as a function of the search detection statistic and with a bin width of 0.2. Search results from the generic transient search (left) and the binary coalescence search (right). Narrow-band features include calibration lines (33–38, 330, and 1080 Hz), vibrational modes of suspension fibers (500 Hz and harmonics), and 60 Hz electric power grid harmonics. The sensitivity is limited by photon shot noise at frequencies above 150 Hz, and by a superposition of other noise sources at lower frequencies. Inset (b): The instrument noise for each detector near the time of the signal detection this is an amplitude spectral density, expressed in terms of equivalent gravitational-wave strain amplitude. Inset (a): Location and orientation of the LIGO detectors at Hanford, WA (H1) and Livingston, LA (L1). While a detector’s directional response is maximal for this case, it is still significant for most other angles of incidence or polarizations (gravitational waves propagate freely through the Earth). The output photodetector records these differential cavity length variations. A gravitational wave propagating orthogonally to the detector plane and linearly polarized parallel to the 4-km optical cavities will have the effect of lengthening one 4-km arm and shortening the other during one half-cycle of the wave these length changes are reversed during the other half-cycle. Simplified diagram of an Advanced LIGO detector (not to scale). Bottom row:A time-frequency representation of the strain data, showing the signal frequency increasing over time. Third row: Residuals after subtracting the filtered numerical relativity waveform from the filtered detector time series. These reconstructions have a 94% overlap, as shown in. The other (light gray) does not use an astrophysical model, but instead calculates the strain signal as a linear combination of sine-Gaussian wavelets. One (dark gray) models the signal using binary black hole template waveforms. Shaded areas show 90% credible regions for two independent waveform reconstructions. Solid lines show a numerical relativity waveform for a system with parameters consistent with those recovered from GW150914 confirmed to 99.9% by an independent calculation based on. Second row: Gravitational-wave strain projected onto each detector in the 35–350 Hz band. 9 − 0.4 + 0.5 ms later at H1 for a visual comparison, the H1 data are also shown, shifted in time by this amount and inverted (to account for the detectors’ relative orientations).
WAVES X NOISE REVIEW SERIES
For visualization, all time series are filtered with a 35–350 Hz bandpass filter to suppress large fluctuations outside the detectors’ most sensitive frequency band, and band-reject filters to remove the strong instrumental spectral lines seen in the Fig. Times are shown relative to Septemat 09:50:45 UTC. The gravitational-wave event GW150914 observed by the LIGO Hanford (H1, left column panels) and Livingston (L1, right column panels) detectors. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger. These observations demonstrate the existence of binary stellar-mass black hole systems. All uncertainties define 90% credible intervals.
0 − 0.5 + 0.5 M ⊙ c 2 radiated in gravitational waves. In the source frame, the initial black hole masses are 3 6 − 4 + 5 M ⊙ and 2 9 − 4 + 4 M ⊙, and the final black hole mass is 6 2 − 4 + 4 M ⊙, with 3. The source lies at a luminosity distance of 41 0 − 180 + 160 Mpc corresponding to a redshift z = 0.0 9 − 0.04 + 0.03. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent to a significance greater than 5.1 σ. It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0 × 10 − 21. On Septemat 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal.