On Black Hole Stability in Critical Gravities

Understand

We consider extended cosmological gravities with Ricci tensor and scalar squared terms in diverse dimensions.

• These theories admit solutions of Einstein metrics, including the Schwarzschild-Tangherlini AdS black holes, whose mass and entropy vanish at the critical point.
• We perform linearized analysis around the black holes and show that in general the spectrum consists of the usual spin-2 massless and ghost massive modes.
• We demonstrate that there is no exponentially-growing tachyon mode in the black holes.