# LIGO gravitational wave chirp signal frequency

This question is about the LIGO gravitational wave signals' frequency. The signals start from about 35 Hz to peak at about 250 Hz, giving evidence of gravitational waves. The question is about the exact frequencies the waves' detection started to the exact peak of the wave.

It seems the LIGO graphs show the peak is a little above 250 Hz. Are there tables published by LIGO that put the start and peak frequencies as 35 to 250 Hz? The graph in the paper by Abbott, et al shows the start and peak (the start is around 36-37 Hz, the peak seems to be at around 256 Hz) - are there exact numbers (tables) for the start and peak, that one can reference?

• Yes. The graph in the paper by Abbott et al. Given the sparseness of the data I doubt three figure precision is warranted. – Rob Jeffries May 29 '16 at 7:02

There's a detailed graph of it here: https://en.wikipedia.org/wiki/First_observation_of_gravitational_waves

What is the most precise reference for your query is the Time-Frequency graphs in black and green, also called waterfall graphs, spectrographs, sonograms and so forth.

On the Y axis, the width of the green smudge is about 30-50Hz, That's the frequency-uncertainty for the TF graph for every wave of the roughly 10 waves that make up the signal.

That's the actual real measurement that LIGO returned, and there are idealized versions here with an uncertainty range of about 5Hz.

If you are interested in sound theory, you can research about Wigner-Ville TF graph, which is the most precise sound analysis mathematics known, and which uses quantum uncertainty estimates to minimize the quantum uncertainty of placing single audio waves in time at a given known frequency. If you have java JVM you can compute a more deeply processed TF graph using sonogram 4 visible speech demo version.

As an synth-reverse-engineering sound scientist, I have to say that the precision of the wave is incredibly clear, it's the same as recording an individual bird chirp from 20 meters away on a clear microphone. Gravity actually has sound, like a bird call, except it's not carried by air compression it's carried by space time at c.

https://losc.ligo.org/s/images/omega_sample.png

• Yes sonogram 4 on java JVM has very advanced sound analyses, except that sound contains so much dense information, we can see all the relevant information from basic graphs. – com.prehensible Jun 5 '18 at 7:46

A fact sheet published by the LIGO collaboration at the time of the announcement of GW150914 (that's the official name of the first detection) gives the peak frequency as "~250 Hz".

The Abbott et al. paper also quotes a value of 35 to 250 Hz in the abstract (I haven't checked for more precise measurements later in the paper, I'm sure the OP or other interested parties can do that independently from the link.)

So I would say that a value of 250 can be quoted as accurate and referenced to Abbott et al. 2016.