Dynamical implications of the Kerr multipole moments for spinning black holes

Abstract

Abstract Previously the linearized stress tensor of a stationary Kerr black hole has been used to determine some of the values of gravitational couplings for a spinning black hole to linear order in the Riemann tensor in the action (worldline or quantum field theory). In particular, the couplings on operators containing derivative structures of the form (𝑆 ∙ ∇)𝑛 acting on the Riemann tensor were fixed, with 𝑆𝜇 the spin vector of the black hole. In this paper we find that the Kerr solution determines all of the multipole moments in the sense of Dixon of a stationary spinning black hole and that these multipole moments determine all linear in 𝑅 couplings. For example, additional couplings beyond the previously mentioned are fixed on operators containing derivative structures of the form 𝑆2𝑛(𝑝 ∙ ∇)2𝑛 acting on the Riemann tensor with 𝑝𝜇 the momentum vector of the black hole. These additional operators do not contribute to the three-point amplitude, and so do not contribute to the linearized stress tensor for a stationary black hole. However, we find that they do contribute to the Compton amplitude. Additionally, we derive formal expressions for the electromagnetic and gravitational Compton amplitudes of generic spinning bodies to all orders in spin in the worldline formalism and evaluated expressions for these amplitudes to 𝒪(𝑆3) in electromagnetism and 𝒪(𝑆5) in gravity.

Keywords

• Effective Field Theories
• Black Holes
• Classical Theories of Gravity