Observation of Gravitational Waves from a Binary Black Hole Merger
On September 14, 2015 at
09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave
Observatory simultaneously observed a transient gravitational-wave signal. The
signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave
strain of 1.0 × 10−21. 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 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 5.1σ. The
source lies at a luminosity distance of 410þ160 −180 Mpc corresponding to a
redshift z ¼ 0.09þ0.03 −0.04 . In the source frame, the initial black hole
masses are 36þ5 −4M⊙ and 29þ4 −4M⊙, and the final black hole mass is 62þ4 −4M⊙, with 3.0þ0.5 −0.5M⊙c2 radiated in gravitational waves. All uncertainties define 90%
credible intervals. These observations demonstrate the existence of binary stellar-mass black hole
systems. This is the first direct detection of gravitational waves and the
first observation of a binary black hole merger.
Gravitational waves
Gravitational waves are
ripples in spacetime which are created whenever objects with mass move.
They were predicted by AlbertEinstein in 1916 on the basis of his theory of general relativity.
As
gravitational waves are not created by stationary objects, they must be
detected from moving systems. Sources of detectable gravitational waves
include binary star systems composed of white dwarfs, neutron stars,
or black holes.
The LIGO detectors have
observed gravitational waves from the merger of two stellar-mass black holes.
The detected waveform matches the predictions of general relativity for the
inspiral and merger of a pair of black holes and the ringdown of the resulting
single black hole. These observations demonstrate the existence of binary
stellar-mass black hole systems. This is the first direct detection of
gravitational waves and the first observation of a binary black hole merger.
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