Uploaded July 2022 | Updated September 2026, 5 days ago
Unlike in Newtonian dynamics, if two gravitationally bound objects are individually spinning in general relativity, their spins will interact and their orbit will precess. This spin precession leaves an imprint on the gravitational wave signal. The catalog of gravitational wave events has already been investigated for spin precession, described using the two effective parameters $\chi_{\rm eff}$ and $\chi_{P}$ (focussing on the spin precession of binary black holes). Here, we repeat the investigation but with a geometrical approach. Spin precession is characterised as the spin precession of the orbital plane, split into its azimuthal motion (its precession) and its polar motion (its nutation). Looking for these effects, and understanding what binary parameters influence them, is non-trivial. We use sequential prior conditioning to resolve this. Prior conditioning is performed by combining prior distributions with posterior distributions of the parameters we're conditioning our priors on. We find that nutation, given its small expected amplitudes, is difficult to constrain. Precession, on the other hand, is clearly constrained, especially for events with highly unequal masses and relatively high signal to noise ratios. We also construct a synthetic binary that we would expect to have a high nutational amplitude, and show that with the future detector sensitivities of ground based gravitational wave observatories, these events are detectable and their nutation can be constrained to be non-zero.
Authors: Daria Gangardt, Davide Gerosa, Michael Kesden, Viola De Renzis, Nathan Steinle
Presenter: Daria Gangardt
Unlike in Newtonian dynamics, if two gravitationally bound objects are individually spinning in general relativity, their spins will interact and their orbit will precess. This spin precession leaves an imprint on the gravitational wave signal. The catalog of gravitational wave events has already been investigated for spin precession, described using the two effective parameters $\chi_{\rm eff}$ and $\chi_{P}$ (focussing on the spin precession of binary black holes). Here, we repeat the investigation but with a geometrical approach. Spin precession is characterised as the spin precession of the orbital plane, split into its azimuthal motion (its precession) and its polar motion (its nutation). Looking for these effects, and understanding what binary parameters influence them, is non-trivial. We use sequential prior conditioning to resolve this. Prior conditioning is performed by combining prior distributions with posterior distributions of the parameters we're conditioning our priors on. We find that nutation, given its small expected amplitudes, is difficult to constrain. Precession, on the other hand, is clearly constrained, especially for events with highly unequal masses and relatively high signal to noise ratios. We also construct a synthetic binary that we would expect to have a high nutational amplitude, and show that with the future detector sensitivities of ground based gravitational wave observatories, these events are detectable and their nutation can be constrained to be non-zero.
Authors: Daria Gangardt, Davide Gerosa, Michael Kesden, Viola De Renzis, Nathan Steinle
Presenter: Daria Gangardt
