Neutron Stars and Pulsars
are rapidly-spinning stars. As they spin, any bumps on (or in) the stars will give off gravitational waves. Because these stars are so amazingly dense, and spin so amazingly quickly, the gravitational waves may be strong enough to detect on Earth. The sound produced will be a single, simple tone.
According to General Relativity theory—as it is currently understood—a black hole
must be a very simple object. It cannot have any bumps or ripples on its surface for very long. Of course, as something falls into the black hole, the hole must
ripple. As the hole settles back down to its quiet, simple state, it will shake off gravitational waves.
A Compact Binary
is a pair of compact objects—white dwarfs, neutron stars, or black holes—in orbit around each other. As they orbit, they give off energy in the form of gravitational waves. This lost energy draws them closer, and causes their orbits to speed up, which makes the sound of their gravitational waves increase in pitch, until they finally meet and merge. The merger represents a mysterious part of General Relativity theory. Physicists expect to find some of the most interesting behavior here.
Extreme Mass-Ratio Inspirals
An Extreme Mass-Ratio Inspiral
is a particular type of Compact Binary. In this pairing, one member is millions of times more massive than the other. This is a particularly "clean" example of an binary, meaning that it is very well understood. The inspiral also takes a very long time. This will allow physicists to make very careful observations of the system.
Collapsing Stars and Supernovae
The violence of a supernova
may provide the tremendous warping of spacetime necessary to give off gravitational waves. If so, the sound would be very brief. This type of wave is called a "burst". Because supernovae are so powerful, and happen so quickly, the gravitational waves should also be very powerful.
The First Moments
Gravitational Wave Detectors
are designed to be extraordinarily sensitive to the tiniest motions of their components. Nothing on Earth can be truly isolated from the rest of the Earth, however, which means that any detector's components will be moving. This will produce a great deal of noise
in the detector's output. Things like earthquakes, and trucks rumbling along nearby highways will produce deep-pitched noise. Just as importantly, lack of laser power will produce high-pitched noise.
for these sounds.