Extremal limits and black hole entropy

Jan, 2009
11 pages
Published in:
  • JHEP 11 (2009) 109
e-Print:
Report number:
  • CALT-68-2717

Citations per year

2009201320172021202502468101214
Abstract: (arXiv)
Taking the extremal limit of a non-extremal Reissner-Nordstr\'om black hole (by externally varying the mass or charge), the region between the inner and outer event horizons experiences an interesting fate -- while this region is absent in the extremal case, it does not disappear in the extremal limit but rather approaches a patch of AdS2×S2AdS_2\times S^2. In other words, the approach to extremality is not continuous, as the non-extremal Reissner-Nordstr\'om solution splits into two spacetimes at extremality: an extremal black hole and a disconnected AdSAdS space. We suggest that the unusual nature of this limit may help in understanding the entropy of extremal black holes.
  • black hole: entropy
  • black hole: Reissner-Nordstroem
  • space-time: anti-de Sitter
  • Einstein-Maxwell equation: solution
  • compactification