GW170104 was a gravitational wave signal detected by the

LIGO The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory designed to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. Two large ...

observatory on 4 January 2017. On 1 June 2017, the LIGO and

Virgo Virgo may refer to: *Virgo (astrology), the sixth astrological sign of the zodiac * Virgo (constellation), a constellation *Virgo Cluster, a cluster of galaxies in the constellation Virgo *Virgo Stellar Stream, remains of a dwarf galaxy * Virgo Su ...

collaborations announced that they had reliably verified the signal, making it the third such signal announced, after

GW150914 The first direct observation of gravitational waves was made on 14 September 2015 and was announced by the LIGO and Virgo collaborations on 11 February 2016. Previously, gravitational waves had been inferred only indirectly, via their effect on ...

and GW151226, and fourth overall.

Event detection

The signal was detected by LIGO at 10:11:58.6 UTC, with the Hanford detector picking it up 3 milliseconds before the Livingston detector. Automated analyses did not initially identify this event as information about the state of the Hanford detector was not being correctly recorded. The event was found by a researcher at the

Max Planck Institute for Gravitational Physics The Max Planck Institute for Gravitational Physics (Albert Einstein Institute) is a Max Planck Institute whose research is aimed at investigating Einstein's theory of relativity and beyond: Mathematics, quantum gravity, astrophysical relativity, a ...

by visual inspection of triggers from the Livingston detector. The gravitational wave frequency at peak GW strain was 160 to 199 Hz.

Astrophysical origin

Analysis indicated the signal resulted from the inspiral and merger of a pair of black holes (BBH) with and times the mass of the Sun, at a

distance Distance is a numerical or occasionally qualitative measurement of how far apart objects or points are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two counties over"). ...

of ( billion light years) from Earth. The resulting black hole had a mass of solar masses, two solar masses having been radiated away as

gravitational energy Gravitational energy or gravitational potential energy is the potential energy a massive object has in relation to another massive object due to gravity. It is the potential energy associated with the gravitational field, which is released (conver ...

. The peak luminosity of GW170104 was .

Implication for binary black hole formation

The spin axes of the black holes were likely misaligned with the axis of the binary orbit. The probability that both spin axes were positively aligned with the orbit is less than 5%. This configuration suggests that the binary black hole system was formed dynamically in a dense star cluster such as a

globular cluster A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of membe ...

, i.e., as a result of gravitational interaction between stars and binary stars, in which case randomly aligned spin axes are expected. The competing scenario, that the system was formed out of a binary star system consisting of two normal ( main sequence) stars, is not ruled out but is disfavored as black holes formed in such a binary are more likely to have positively aligned spins.

Graviton mass upper limit

The analysis of GW170104 yielded a new upper bound on the

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different eleme ...

graviton In theories of quantum gravity, the graviton is the hypothetical quantum of gravity, an elementary particle that mediates the force of gravitational interaction. There is no complete quantum field theory of gravitons due to an outstanding mathem ...

s, if gravitons are massive at all. The graviton's

Compton wavelength The Compton wavelength is a quantum mechanical property of a particle. The Compton wavelength of a particle is equal to the wavelength of a photon whose energy is the same as the rest energy of that particle (see mass–energy equivalence). It was ...

is at least , or about 1.6 light-years, corresponding to a graviton mass of no more than . This Compton wavelength is about times greater than the gravitational wavelength of the GW170104 event.

References

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Event detection

Astrophysical origin

Implication for binary black hole formation

Graviton mass upper limit

See also

References