Spontaneous scalarization of charged black holes at the approach to extremality

Author(s)

Brihaye, Yves ^[1] ; Hartmann, Betti ^[2]

Affiliation

^[1] Univ Mons Hainaut, Phys Math, B-7000 Mons - Belgium

^[2] Univ Sao Paulo, IFSC, CP 369, BR-13560970 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Physics Letters B; v. 792, p. 244-250, MAY 10 2019.
• Web of Science Citations: 7

Abstract

We study static, spherically symmetric and electrically charged black hole solutions in a quadratic Einstein-scalar-Gauss-Bonnet gravity model. Very similar to the uncharged case, black holes undergo spontaneous scalarization for sufficiently large scalar-tensor coupling gamma - a phenomenon attributed to a tachyonic instability of the scalar field system. While in the uncharged case, this effect is only possible for positive values of gamma, we show that for sufficiently large values of the electric charge Q two independent domains of existence in the gamma-Q-plane appear: one for positive gamma and one for negative gamma. We demonstrate that this new domain for negative gamma exists because of the fact that the near-horizon geometry of a nearly extremally charged black hole is AdS(2) x S-2. This new domain appears for electric charges larger than approximately 74% of the extremal charge. For positive y we observe that a singularity with diverging curvature invariants forms outside the horizon when approaching extremality. (C) 2019 The Author(s). Published by Elsevier B.V. (AU)

• FAPESP's process: 16/12605-2 - (In)stability and excitation of modes in (asymptotically) Anti-de Sitter space-times with view to the AdS/CFT correspondence
• Grantee: Betti Hartmann
• Support Opportunities: Regular Research Grants