# Third Detection of Gravitational Waves by LIGO

Scientists report the third detection of gravitational waves by LIGO (Laser Interferometer Gravitational-Wave Observatory), their findings being published in the Physical Review Letters. An analysis of the event, named GW170104, shows the merger of two black holes having 31 and 19 solar masses.

See the abstract below:

We describe the observation of GW170104, a gravitational-wave signal produced by the coalescence of a pair of stellar-mass black holes. The signal was measured on January 4, 2017 at 10∶11:58.6 UTC by the twin advanced detectors of the Laser Interferometer Gravitational-Wave Observatory during their second observing run, with a network signal-to-noise ratio of 13 and a false alarm rate less than 1 in 70 000 years. The inferred component black hole masses are 31.2+8.46.0M and 19.4+5.35.9M (at the 90% credible level). The black hole spins are best constrained through measurement of the effective inspiral spin parameter, a mass-weighted combination of the spin components perpendicular to the orbital plane, χeff=0.12+0.210.30. This result implies that spin configurations with both component spins positively aligned with the orbital angular momentum are disfavored. The source luminosity distance is 880+450390Mpc corresponding to a redshift of z=0.18+0.080.07. We constrain the magnitude of modifications to the gravitational-wave dispersion relation and perform null tests of general relativity. Assuming that gravitons are dispersed in vacuum like massive particles, we bound the graviton mass to mg7.7×1023eV/c2. In all cases, we find that GW170104 is consistent with general relativity.

The full text can be found here.

Attribution: GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2B. P. Abbott et al. (LIGO Scientific and Virgo Collaboration)

Phys. Rev. Lett. 118, 221101 – Published 1 June 2017

DOI: https://doi.org/10.1103/PhysRevLett.118.221101

Image source: LIGO/Caltech/MIT/Sonoma State (A. Simonnet)

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