2025/03/21 by Batoul Banihashemi, Banihashemi, Batoul, Edgar Shaghoulian +3 · 7 citations
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Astrophysical Phenomena and Observations
paper · pdf · doi:10.48550/arxiv.2503.17471
Recent work has studied the thermodynamics of gravity subjected to conformal boundary conditions, where the trace of the extrinsic curvature K and the conformal class of metrics are kept fixed. The case K < 0 seems tied to solutions with cosmic horizons. To study this situation further, we analyze Einstein-Maxwell theory, where we find solutions with cosmic horizons corresponding to patches inside the inner horizon of the Reissner-Nordström black hole. We find that these solutions are \itnecessary for consistency with the thermal effective action in the putative boundary dual at O(1) chemical potential. Furthermore, we introduce a (positive or negative) cosmological constant and find more cases where solutions with cosmic horizons dominate the ensemble. Transitions between solutions with cosmic horizons and solutions with black hole horizons are mediated by "extremal" solutions that correspond to patches of (A)dS2 × Σd-1, for which we discuss an effective JT gravity description with dimensionally reduced conformal boundary conditions. Finally, we introduce rotation in some simple cases and find that the bulk theory reproduces the universal velocity-dependent modification of the free energy predicted by the thermal effective action.