发表机构
Indian Institute of Technology (Indian School of Mines)（印度理工学院（矿业学院））
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文通过非极端近视界展开的二阶标度方法，恢复极端黑洞喉管几何，并统一推导出多种已知黑洞的近视界系数。
AI 中文摘要
我们展示了如何从光滑稳态黑洞族（允许光滑极端极限）的非极端近视界展开中恢复极端近视界几何。在族内通用的高斯零坐标中，我们应用表面引力的近极端标度，连同径向标度和Killing时间的重新标度。尽管物理表面引力消失，标度后的视界仍可保留有限的表面引力。当该标度表面引力趋于零时，即得到极端近视界几何。在近极端标度和时间重新标度下，时间度规分量中的二次径向项可以存活，而更高径向阶则消失。因此，展开到二阶是充分的，并且当所选坐标图中二次项具有非零极限系数时是必要的。我们推导了一种通用的拉回处方来提取近视界系数，并恢复了Reissner-Nordström、Kerr、Kerr-Newman以及带电旋转Bañados-Teitelboim-Zanelli（BTZ）黑洞的已知喉管。中性旋转BTZ提供了一个弦Carroll展开已足够的案例。
英文摘要
We show how extremal near horizon geometries can be recovered from the non extremal near horizon expansion for smooth stationary black hole families admitting a smooth extremal limit. In Gaussian null coordinates common to the family, we apply the near extremal scaling of the surface gravity together with a radial scaling and a rescaling of Killing time. Although the physical surface gravity vanishes, the scaled horizon can retain a finite surface gravity. The extremal near horizon geometry is obtained when this scaled surface gravity is taken to zero. Under the near extremal scaling and the time rescaling, the quadratic radial term in the temporal metric component can survive, while higher radial orders vanish. Expansion through second order is therefore sufficient and is necessary whenever the quadratic term has a nonzero limiting coefficient in the chosen chart. We derive a common pullback prescription for extracting the near horizon coefficients and recover the known throats of Reissner-Nordström, Kerr, Kerr-Newman, and charged rotating Bañados-Teitelboim-Zanelli (BTZ) black holes. Neutral rotating BTZ provides a case in which the string Carroll expansion already suffices.
