Sources & Sounds
Gravitational wave "sources" are the astrophysical objects or phenomena that disturb spacetime and produce gravitational waves: colliding black holes, spinning neutron stars, supernova explosions, and the Big Bang itself. From here or the menu bar above, you can navigate to different pages that explore the different kinds of gravitational-wave signals produced by these sources (along with their audio representations).
This site is a still a work in progress, and we plan to keep adding more sources & sounds on a regular basis. So far, we have focused on inspiraling compact binaries, which are the key source for LIGO and other ground-based gravitational-wave detectors. (They also produce the most interesting sounds.)
Here are our current offerings:
We have many more sources & sounds in the works. In the inspiraling binaries category we plan to include more sophisticated features in our waveform models and investigate their effects. We will add extreme-mass-ratio inspirals (a small black hole inspiralling into a much larger one) and also unbound binaries (compact objects on hyperbolic orbits). Besides binary sources, we will be adding sounds for supernova explosions, cosmic strings, single rotating neutron stars, and stochastic backgrounds. We'll also include some stereo sounds to simulate the effect of multiple gravitational-wave detectors. Just as having two ears helps you triangulate the direction of a sound, two or more detectors can likewise help determine the direction a gravitational wave originates from. And as more gravitational wave signals are detected, we'll be adding those as well.
Stay tuned!
This site is a still a work in progress, and we plan to keep adding more sources & sounds on a regular basis. So far, we have focused on inspiraling compact binaries, which are the key source for LIGO and other ground-based gravitational-wave detectors. (They also produce the most interesting sounds.)
Here are our current offerings:
- Detector Noise. Listen to what the initial LIGO detector "sounds" like in the absence of any detectable signal. We also explore adding a very faint (fake) signal to the noise to illustrate the challenging data analysis problem that LIGO scientists face.
- Binaries: the basics. Learn a bit about the gravitational-wave signal from two coalescing black holes, including the different phases of the signal. We also explore the role of the total mass of the binary and the effect of neglecting the final merger of the two black holes.
- Circular Binaries. Here we focus on two compact objects (neutron stars or black holes) in a circular orbit that is shrinking due to the gravitational waves that are emitted. We expect this to be the most common LIGO source.
- Spinning Binaries. Now we allow our individual stars to spin about each of their axes. Because the spin of a body affects its gravity in Einstein's theory, we will see that the gravitational-wave signal (and the corresponding sound) is likewise affected.
- Elliptical Binaries. When we allow the binary orbit to be elliptical the "sound" of the signal become even more interesting.
- Detection! Here you can learn about the first direct detection of gravitational waves as announced on February 11, 2016. This event---labeled GW150914---arose from the merger of two black holes. Unlike the other "sounds" on our site (which are produced by mathematical models), this one is the real thing! Learn how the signal can be picked out of the detector noise. That page includes some stereo sounds as well.
- Detections. This section collects separate pages for LIGO detections that followed GW150914. So far this includes GW151226 and GW170104.
We have many more sources & sounds in the works. In the inspiraling binaries category we plan to include more sophisticated features in our waveform models and investigate their effects. We will add extreme-mass-ratio inspirals (a small black hole inspiralling into a much larger one) and also unbound binaries (compact objects on hyperbolic orbits). Besides binary sources, we will be adding sounds for supernova explosions, cosmic strings, single rotating neutron stars, and stochastic backgrounds. We'll also include some stereo sounds to simulate the effect of multiple gravitational-wave detectors. Just as having two ears helps you triangulate the direction of a sound, two or more detectors can likewise help determine the direction a gravitational wave originates from. And as more gravitational wave signals are detected, we'll be adding those as well.
Stay tuned!
[Above figure: R. Hurt - Caltech / JPL ]
