How do they know that the gravitational waves that were detected were from two Black Holes colliding together?

[The]

To avoid confusion, I understand what gravitational waves are and I am convinced that they were detected. I am not questioning the detection of gravity waves.

 

LIGO did detect gravity waves as they passed through earth.

 

What I want to know is how did they know that it was the collision of two black holes that caused those gravity waves to form.

 

I mean after all there are other ginormous objects in space whose collisions can also cause gravity waves, two neutron stars colliding into each other.

 

So how do they know that the waves that LIGO found, where from 2 Black Holes colliding together and nothing else.

[Strange]

Different sources will create different patterns of waves. They have a large library of "templates" of the waves that would be generated by different types of sources (supernova, pairs of black holes, pairs of neutron stars, black hole + neutron star, etc). These are created by simulating these events.

 

They find the best template match and then run more simulations to pin down the exact match. That way they can determine the masses of the black holes. From that they know the energy of the gravitational waves and then, by comparing that with the waves received, the distance.

 

All the detail you could possibly want here: http://cplberry.com/2016/02/23/gw150914-the-papers/

[StringJunky]

From the horse's mouth:

 

 

How do we know GW150914 was a black hole merger?

 

Our estimated pre-merger masses of the two components in GW150914 make a very strong argument that they are both black holes - particularly when we also consider the enormous velocity and tiny separation of the two components, as shown in the lower part of figure 3. In this figure indicative velocities of the two components are seen to be significant fractions of the speed of light. Similarly their approximate separation is shown to be just a few times the characteristic size of a black hole, known as its Schwarzschild radius.

 

These graphs imply that the two components were only a few hundred kilometers apart just before they merged, ie. when the gravitational-wave frequency was about 150 Hz. Black holes are the only known objects compact enough to get this close together without merging. Based on our estimated total mass for the two components, a pair of neutron stars would not be massive enough, and a black hole-neutron star pair would have already merged at a lower frequency than 150 Hz.

 

http://www.ligo.org/science/Publication-GW150914/index.php

Edited March 26, 2016 by StringJunky

[The]

Thx for the replies guys, Explained it.