Non-linear tides and Gauss-Bonnet scalarization

• DOI: 10.1016/j.physletb.2023.138137
• Publication Date: 2023-08-22T15:58:04Z
• Authors: Lorenzo Annulli; Carlos A.R. Herdeiro
• Keywords: High Energy Physics - Theory; High Energy Physics - Theory (hep-th); Physics; QC1-999; FOS: Physical sciences; General Relativity and Quantum Cosmology (gr-qc); General Relativity and Quantum Cosmology

13 pages, 13 figures<br/>In linear perturbation theory, a static perturber in the vicinity of a Schwarzschild black hole (BH) enhances [suppresses] the Gauss-Bonnet (GB) curvature invariant, $\mathcal{R}_{\rm GB}$, in the high [low] tide regions. By analysing exact solutions of the vacuum Einstein field equations describing one or two BHs immersed in a multipolar gravitational field, which is locally free of pathologies, including conical singularities, we study the corresponding non-linear tides on a fiducial BH, in full General Relativity (GR). We show that the tidal field due to a far away, or close by, static BH creates high/low tides that can deviate not only quantitatively but also qualitatively from the weak field/Newtonian pattern. Remarkably, the suppression in low tide regions never makes $\mathcal{R}_{\rm GB}$ negative on the BH, even though the horizon Gaussian curvature may become negative; but $\mathcal{R}_{\rm GB}$ can vanish in a measure zero set, a feature qualitatively recovered in a Newtonian analogue model. Thus, purely gravitational, static, tidal interactions in GR, no matter how strong, cannot induce GB$^-$ scalarization. We also show that a close by BH produces noticeable asymmetric tides on another (fiducial) BH.<br/>