Decreasing entropy of dynamical black holes in critical gravity

Abstract

Critical gravity is a quadratic curvature gravity in four dimensions which is ghost-free around the AdS background. Constructing a Vaidya-type exact solution, we show that the area of a black hole defined by a future outer trapping horizon can shrink by injecting a charged null fluid with positive energy density, so that a black hole is no more a one-way membrane even under the null energy condition. In addition, the solution shows that the Wald-Kodama dynamical entropy of a black hole is negative and can decrease. These properties expose the pathological aspects of critical gravity at the non-perturbative level.

11 pages, no figure, 2 tables; v2, revised version with more references; v3, final version to appear in JHEP

References in corpus (10)

• Massive Gravity in Three Dimensions
• More on Massive 3D Gravity
• Critical Gravity in Four Dimensions
• Critical Points of D-Dimensional Extended Gravities
• Note on New Massive Gravity in $Ad{S}_3$
• Robinson-Trautman spacetimes in higher dimensions
• Renormalizability of Massive Gravity in Three Dimensions
• Dynamical black holes with symmetry in Einstein-Gauss-Bonnet gravity
• Robinson-Trautman spacetimes with an electromagnetic field in higher dimensions
• Black-hole dynamics in BHT massive gravity

Cited by in corpus (3)

• Einstein Gravity from Conformal Gravity in 6D
• Energy in Higher-Derivative Gravity via Topological Regularization
• Phase Transition of the Horava-Lifshitz AdS black holes