http://arxiv.org/abs/2208.07380
The gravitational wave strain emitted by a perturbed black hole (BH) ringing down is typically modeled analytically using first-order BH perturbation theory. In this Letter we show that second-order effects are necessary for modeling ringdowns from BH merger simulations. Focusing on the strain’s $(\ell,m)=(4,4)$ angular harmonic, we show the presence of a quadratic effect across a range of binary BH mass ratios that agrees with theoretical expectations. We find that the quadratic $(4,4)$ mode amplitude exhibits quadratic scaling with the fundamental $(2,2)$ mode — its parent mode. The nonlinear mode’s amplitude is comparable to or even larger than that of the linear $(4,4)$ modes. Therefore correctly modeling ringdown — improving mismatches by an order of magnitude — requires the inclusion of nonlinear effects.
K. Mitman, M. Lagos, L. Stein, et. al.
Wed, 17 Aug 22
57/58
Comments: 5+2 pages, 4 figures, 1 table
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