Spherical collapse in scalar-Gauss-Bonnet gravity: Taming ill-posedness with a Ricci coupling

Thaalba, Farid; Bezares, Miguel; Franchini, Nicola; Sotiriou, Thomas P.

Abstract

We study spherical collapse of a scalar cloud in scalar-Gauss-Bonnet gravity—a theory in which black holes can develop scalar hair if they are in a certain mass range. We show that an additional quadratic coupling of the scalar field to the Ricci scalar can mitigate loss of hyperbolicity problems that have plagued previous numerical collapse studies and instead lead to well-posed evolution. This suggests that including specific additional interactions can be a successful strategy for tackling well-posedness problems in effective field theories of gravity with nonminimally coupled scalars. Our simulations also show that spherical collapse leads to black holes with scalar hair when their mass is below a mass threshold and above a minimum mass bound and that above the mass threshold, the collapse leads to black holes without hair, in line with results in the static case and perturbative analyses. For masses below the minimum mass bound, we find that the scalar cloud smoothly dissipates, leaving behind flat space.

Citation

Thaalba, F., Bezares, M., Franchini, N., & Sotiriou, T. P. (2024). Spherical collapse in scalar-Gauss-Bonnet gravity: Taming ill-posedness with a Ricci coupling. Physical Review D, 109(4), L041503. https://doi.org/10.1103/physrevd.109.l041503

• Journal Article Type: Article
• Acceptance Date: Jan 12, 2024
• Online Publication Date: Feb 20, 2024
• Publication Date: Feb 15, 2024
• Deposit Date: Feb 26, 2024
• Publicly Available Date: Feb 26, 2024
• Journal: Physical Review D
• Print ISSN: 2470-0010
• Electronic ISSN: 2470-0029
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 109
• Issue: 4
• Article Number: L041503
• Pages: L041503
• DOI: https://doi.org/10.1103/physrevd.109.l041503
• Keywords: Alternative gravity theories; Classical black holes
• Public URL: https://nottingham-repository.worktribe.com/output/31619271
• Publisher URL: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.109.L041503