Blackfolds in (Anti)-de Sitter Backgrounds
Jay Armas, Niels A. Obers
TL;DR
The authors extend the blackfold methodology to (A)dS$_D$ backgrounds to systematically explore neutral black hole solutions with novel horizon topologies, in the regime where the cosmological scale far exceeds the transverse horizon size. By constructing odd-sphere and product-of-odd-spheres blackfolds, and analyzing both AdS and dS cases, they derive equilibrium conditions, thermodynamic properties, and stability criteria, linking many of these solutions to limits of Kerr-(A)dS black holes, including ultraspinning regimes that yield pancaked geometries. They show that AdS blackfolds tend to be thermodynamically unstable while certain dS cases admit restricted stability windows, and they demonstrate that even-ball blackfolds reproduce two distinct ultra-spinning Kerr-AdS limits, thereby providing a geometric interpretation of these spacetimes within the blackfold framework. The work also uncovers helically symmetric rings in (A)dS, highlighting the potential saturation of the rigidity theorem and setting the stage for future hydrodynamic and higher-order investigations relevant to AdS/CFT and the fluid/gravity correspondence.
Abstract
We construct different neutral blackfold solutions in Anti-de Sitter and de Sitter background spacetimes in the limit where the cosmological scale is taken to be much larger than the transverse horizon size. This includes a class of blackfolds with horizons that are products of odd-spheres times a transverse sphere, for which the thermodynamic stability is also studied. Moreover, we exhibit a specific case in which the same blackfold solution can describe different limiting black hole spacetimes therefore illustrating the geometric character of the blackfold approach. Furthermore, we show that the higher-dimensional Kerr-(Anti)-de Sitter black hole allows for ultra-spinning regimes in the relevant limit of large cosmological scale, and demonstrate that this is correctly described by a pancaked blackfold geometry. We also give evidence for the possibility of saturating the rigidity theorem in these backgrounds.