= Binary black hole
A binary black hole is a <binary system> whose two components are <black holes>. <Gravitational waves> carry away <orbital energy> and <angular momentum>, gradually reducing the separation; sufficiently close systems progress through inspiral, merger and the settling of the final <black hole>. The increasing <orbital angular velocity> produces a signal whose <gravitational-wave frequency> rises, called a <chirp>. In <GW150914>, two <LIGO> <interferometers> recorded a signal sweeping from about 35 to 250 <hertz> in September 2015. Comparing that measured <gravitational wave> <strain> with <general relativity> waveforms inferred the component <masses> and the merger's properties. This permits the study of systems that need no luminous surrounding <gas> to be detected.<Observation of Gravitational Waves from a Binary Black Hole Merger by B. P. Abbott and others>[Abstract: 14 September 2015 signal, upward frequency sweep and agreement with inspiral, merger and ringdown waveforms]{ref}
Back to article page
