A unique (so far) gravitational wave signal

[Judi Lynn]

Posted by EarthSky Voices in SPACE | April 26, 2020
LIGO and Virgo detectors have now captured the first gravitational waves from a binary black hole merger where the black hole masses are unequal.

Originally published by the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, or AEI) in Hannover, Germany, on April 20, 2020.

The expectations of the gravitational-wave research community have been fulfilled: gravitational-wave discoveries are now part of their daily work as they have identified in the past observing run, O3, new gravitational-wave candidates about once a week. But now, the researchers have published a remarkable signal unlike any of those seen before: GW190412 is the first observation of a binary black hole merger where the two black holes have distinctly different masses of about 8 and 30 times that of our sun. This not only has allowed more precise measurements of the system’s astrophysical properties, but it has also enabled the LIGO and Virgo scientists to verify a yet-untested prediction of Einstein’s theory of general relativity.

Frank Ohme is leader of an independent research group at Max Planck called Binary Merger Observations and Numerical Relativity. He commented:

For the very first time we have ‘heard’ in GW190412 the unmistakable gravitational-wave hum of a higher harmonic, similar to overtones of musical instruments. In systems with unequal masses like GW190412 – our first observation of this type – these overtones in the gravitational-wave signal are much louder than in our usual observations. This is why we couldn’t hear them before, but in GW190412, we finally can.

More:
https://earthsky.org/space/a-gravitational-wave-signal-like-none-before