Measuring precession in asymmetric compact binaries

Understand

Gravitational-wave observations of merging compact binaries hold the key to precision measurements of the objects' masses and spins.

• General-relativistic precession, caused by spins misaligned with the orbital angular momentum, is considered a crucial tracer for determining the binary's formation history and environment, and it also improves mass estimates -- its measurement is therefore of particular interest with wide-ranging implications.
• Precession leaves a characteristic signature in the emitted gravitational-wave signal that is even more pronounced in binaries with highly unequal masses.
• The recent observations of GW190412 and GW190814 have confirmed the existence of such asymmetric compact binaries.