2020/10/14 by Horng Sheng Chia · 1 voice · 165 citations
Physics and Astronomy · #Angular momentum #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Binary black hole #Black hole (networking) #Classical mechanics #Dissipative system #Event horizon #General relativity #Gravitation #Gravitational wave #Physics #Pulsars and Gravitational Waves Research #Quantum mechanics #Rotating black hole #Spacetime #astro-ph.HE #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.104.024013
published in Physical review. D/Physical review. D. 104(2) (American Physical Society) · 6+1 pages, 1 figure; updated to match published version
arxiv created 2021/07/06 · openalex publication_date 2021/07/06 · arxiv updated 2021/07/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We show that rotating black holes do not experience any tidal deformation when they are perturbed by a weak and adiabatic gravitational field. The tidal deformability of an object is quantified by the so-called ``Love numbers,'' which describe the object's linear response to its external tidal field. In this work, we compute the Love numbers of Kerr black holes and find that they vanish identically. We also compute the dissipative part of the black hole's tidal response, which is nonvanishing due to the absorptive nature of the event horizon. Our results hold for arbitrary values of black hole spin, for both the electric-type and magnetic-type perturbations, and to all orders in the multipole expansion of the tidal field. The boundary conditions at the event horizon and at asymptotic infinity are incorporated in our study, as they are crucial for understanding the way in which these tidal effects are mapped onto gravitational-wave observables. In closing, we address the ambiguity issue of Love numbers in general relativity, which we argue is resolved when those boundary conditions are taken into account. Our findings provide essential inputs for current efforts to probe the nature of compact objects through the gravitational waves emitted by binary systems.