Black Holes In Anti-de Sitter Space Research Articles

Critical behavior of charged dilaton black holes in AdS space

We revisit critical behaviour and phase structure of charged anti-deSitter (AdS) dilaton black holes for arbitrary values of dilaton coupling $\alpha$, and realize several novel phase behaviour for this system. We adopt the viewpoint that cosmological constant (pressure) is fixed and treat the charge of the black hole as a thermodynamical variable. We study critical behaviour and phase structure by analyzing the phase diagrams in $T-S$ and $ q-T$ planes. We numerically derive the critical point in terms of $\alpha$ and observe that for $\alpha =1$ and $\alpha \geq \sqrt{3}$, the system does not admit any critical point, while for $0<\alpha <1$, the critical quantities are not significantly affected by $\alpha$. We find that unstable behavior of the Gibbs free energy for $q<q_{c}$ exhibits a \textit{first order} (discontinuous) phase transition between small and large black holes for $0\leq\alpha<1$. For $1<\alpha <\sqrt{3}$ and $q>q_{c}$, however, a novel first order phase transition occurs between small and large black hole, which has not been observed in the previous studies on phase transition of charged AdS black holes.

Instability of rotating black holes: large D analysis

We study the stability of odd-dimensional rotating black holes with equal angular momenta by performing an expansion in the inverse of the number of dimensions D. Universality at large $D$ allows us to calculate analytically the complex frequency of quasinormal modes to next-to-leading order in the expansion. We identify the onset of non-axisymmetric, bar-mode instabilities at a specific finite rotation, and axisymmetric instabilities at larger rotation. The former occur at the threshold where the modes become superradiant, and before the ultraspinning regime is reached. Our results fully confirm the picture found in numerical studies, with very good quantitative agreement. We extend the analysis to the same class of black holes in Anti-deSitter space, and find the same qualitative features. We also discuss the appearance at high frequencies of the universal set of (stable) quasinormal modes.

Viscosity to entropy ratio at extremality

Assuming gauge theory realization at the boundary, we show that the viscosity to entropy ratio is 1/(4π) where the bulk is represented by a large class of extremal black holes in anti-deSitter space. In particular, this class includes multiple R-charged black holes in various dimensions.

AdS/CFT duals of topological black holes and the entropy of zero-energy states

The horizon of a static black hole in Anti-deSitter space can be spherical, planar, or hyperbolic. The microscopic dynamics of the first two classes of black holes have been extensively discussed recently within the context of the AdS/CFT correspondence. We argue that hyperbolic black holes introduce new and fruitful features in this respect, allowing for more detailed comparisons between the weak and strong coupling regimes. In particular, by focussing on the stress tensor and entropy of some particular states, we identify unexpected increases in the entropy of Super-Yang-Mills theory at strong coupling that are not accompanied by increases in the energy. We describe a highly degenerate state at zero temperature and zero energy density. We also find that the entanglement entropy across a Rindler horizon in exact AdS_5 is larger than might have been expected from the dual SYM theory. Besides, we show that hyperbolic black holes can be described as thermal Rindler states of the dual conformal field theory in flat space.