Thermodynamics of near BPS black holes in AdS4 and AdS7

We develop the thermodynamics of black holes in AdS4 and AdS7 near their BPS limit. In each setting we study the two distinct deformations orthogonal to the BPS surface as well as their nontrivial interplay with each other and with BPS properties. Our results illuminate recent microscopic calculations of the BPS entropy. We show that these microscopic computations can be leveraged to also describe the near BPS regime, by generalizing the boundary conditions imposed on states.

Flat space holography in spin-2 extended dilaton-gravity

We present an interacting spin-2 gauge theory coupled to the two-dimensional dilaton-gravity in flat spacetime. The asymptotic symmetry group is enhanced to the central extension of Diff(S1)⋉C∞(S1)⋉Vec(S1) when the central element of the Heisenberg subgroup is zero (vanishing U(1) level). Using the BF-formulation of the model we derive the corresponding boundary coadjoint action which is the spin-2 extension of the warped Schwarzian theory at vanishing U(1) level. We also discuss the thermodynamics of black holes in this model.

Varying Newton Constant and Black Hole to White Hole Quantum Tunneling

The thermodynamics of black holes is discussed for the case, when the Newton constant G is not a constant, but it is the thermodynamic variable. This gives for the first law of the Schwarzschild black hole thermodynamics: dSBH=−AdK+dMTBH, where the gravitational coupling K=1/4G, M is the black hole mass, A is the area of horizon, and TBH is Hawking temperature. From this first law, it follows that the dimensionless quantity M2/K is the adiabatic invariant, which, in principle, can be quantized if to follow the Bekenstein conjecture. From the Euclidean action for the black hole it follows that K and A serve as dynamically conjugate variables. Using the Painleve–Gullstrand metric, which in condensed matter is known as acoustic metric, we calculate the quantum tunneling from the black hole to the white hole. The obtained tunneling exponent suggests that the temperature and entropy of the white hole are negative.

Varying Newton Constant and Black Hole to White Hole Quantum Tunneling

The thermodynamics of black holes is discussed for the case, when the Newton constant G is not a constant, but is the thermodynamic variable. This gives for the first law of the Schwarzschild black hole thermodynamics: d S BH = − A d K + d M T BH , where the gravitational coupling K = 1 / 4 G , M is the black hole mass, A is the area of horizon, and T BH is Hawking temperature. From this first law it follows that the dimensionless quantity M 2 / K is the adiabatic invariant, which in principle can be quantized if to follow the Bekenstein conjecture. From the Euclidean action for the black hole it follows that K and A serve as dynamically conjugate variables. This allows us to calculate the quantum tunneling from the black hole to the white hole, and determine the temperature and entropy of the white hole.

Non-Singular Model of Magnetized Black Hole Based on Nonlinear Electrodynamics

A new modified Hayward metric of magnetically charged non-singular black hole spacetime in the framework of nonlinear electrodynamics is constructed. When the fundamental length introduced, characterising quantum gravity effects, vanishes, one comes to the general relativity coupled with the Bronnikov model of nonlinear electrodynamics. The metric can have one (an extreme) horizon, two horizons of black holes, or no horizons corresponding to the particle-like solution. Corrections to the Reissner–Nordström solution are found as the radius approaches infinity. As r → 0 the metric has a de Sitter core showing the absence of singularities, the asymptotic of the Ricci and Kretschmann scalars are obtained and they are finite everywhere. The thermodynamics of black holes, by calculating the Hawking temperature and the heat capacity, is studied. It is demonstrated that phase transitions take place when the Hawking temperature possesses the maximum. Black holes are thermodynamically stable at some range of parameters.

Nonsingular Model of Magnetized Black Hole Based on Nonlinear Electrodynamics

We find solutions of a magnetically charged non-singular black hole in some modified theory of gravity coupled with nonlinear electrodynamics. The metric of a magnetized black hole is obtained which has one (an extreme horizon), two horizons, or no horizons (naked singularity). Corrections to the Reissner-Nordstrom solution are found as the radius approaches to infinity. The asymptotic of the Ricci and Kretschmann scalars are calculated showing the absence of singularities. We study the thermodynamics of black holes by calculating the Hawking temperature and the heat capacity. It is demonstrated that phase transitions take place and we show that black holes are thermodynamically stable at some range of parameters.

Extended phase-space thermodynamics of black holes in massive gravity

We study the extended phase-space thermodynamics of black holes in massive gravity. Particularly, we examine the critical behavior of this black hole using the extended phase-space formalism. Extended phase-space can be defined as one in which the cosmological constant should be treated as a thermodynamic pressure and its conjugate variable as a thermodynamic volume. In this phase-space, we derive the black hole equation of state, the critical pressure, the critical volume and the critical temperature at the critical point. We also derive the critical ratio of this black hole. Moreover, we derive the black hole reduced equation of state in terms of the reduced pressure, the reduced volume and the reduced temperature. Furthermore, we examine the Ehrenfest equations of black holes in massive gravity in the extended phase-space at the critical point. We show that the Ehrenfest equations are satisfied on this black hole and the black hole encounters a second-order phase transition at the critical point in the said phase-space. This is re-examined by evaluating the Pregogine–Defay ratio [Formula: see text]. We determine the value of this ratio is [Formula: see text]. The outcome of this study is completely analogous to the nature of liquid–gas phase transition at the critical point. This investigation also further gives us the profound understanding between the black hole of massive gravity with the liquid–gas system.