GW170814: A Three-Detector Observation of Gravitational Waves from a Binary Black Hole Coalescence

TLDR

The study enables, for the first time, testing gravitational‑wave polarizations via the LIGO‑Virgo antenna response, opening a new class of phenomenological gravity tests. On 14 August 2017, a three‑detector network observed a gravitational‑wave signal from a binary black‑hole merger with a false‑alarm rate of ≲1 in 27 000 years, an SNR of 18, component masses of 30.5 M⊙ and 25.3 M⊙, a luminosity distance of 540 Mpc (z≈0.11), and a sky‑localization area reduced to 60 deg² from 1160 deg².

Abstract

On August 14, 2017 at 10∶30:43 UTC, the Advanced Virgo detector and the two Advanced LIGO detectors coherently observed a transient gravitational-wave signal produced by the coalescence of two stellar mass black holes, with a false-alarm rate of ≲1 in 27 000 years. The signal was observed with a three-detector network matched-filter signal-to-noise ratio of 18. The inferred masses of the initial black holes are 30.5_{-3.0}^{+5.7}M_{⊙} and 25.3_{-4.2}^{+2.8}M_{⊙} (at the 90% credible level). The luminosity distance of the source is 540_{-210}^{+130} Mpc, corresponding to a redshift of z=0.11_{-0.04}^{+0.03}. A network of three detectors improves the sky localization of the source, reducing the area of the 90% credible region from 1160 deg^{2} using only the two LIGO detectors to 60 deg^{2} using all three detectors. For the first time, we can test the nature of gravitational-wave polarizations from the antenna response of the LIGO-Virgo network, thus enabling a new class of phenomenological tests of gravity.