nLab extremal black hole

Idea

For a charged and/or rotating black hole (Kerr spacetime, Reissner-Nordstrom spacetime, Kerr-Newman spacetime) there is a minimum possible mass for given charge and angular momentum. When this minimum is attained, one hence speaks of an extremal black hole.

Properties

Near horizon geometry and JT gravity

The near horizon geometry of extremal black holes in $d$ dimensional spacetime is anti de Sitter spacetime $AdS_{2}$ (KLR 07, AGJST 06, AY 07, ANT 07).

The $AdS_2 \times S^{d-2}$ near horizon geometry of near-extremal black holes is well approximated by Jackiw-Teitelboim gravity (NSST 18, MTV 18).

Related concepts

• black holes in string theory, black brane

• BPS state

• Bridgeland stability condition

References

General

• Tatsuo Azeyanagi, Tatsuma Nishioka, Tadashi Takayanagi, Near Extremal Black Hole Entropy as Entanglement Entropy via $AdS_2/CFT_1$, Phys.Rev.D77:064005,2008 (arXiv:0710.2956)

• Sean Carroll, Matthew C. Johnson, Lisa Randall, Extremal limits and black hole entropy, JHEP 0911:109,2009 (arXiv:0901.0931)

• Ashoke Sen, Extremal black holes, talk slides 2009 (pdf)

See also

• Wikipedia, Extremal black hole

BH entropy

On black hole entropy of (near-)extremal black holes:

• Luca Iliesiu, From statistical mechanics to microstate counting for extremal and near-extremal black holes, talk at Strings 2022 [indico:4940850, slides, video]

Near-horizon geometry and JT gravity

Discussion of the near horizon geometry

• Hari K. Kunduri, James Lucietti, Harvey S. Reall, Near-horizon symmetries of extremal black holes, Class.Quant.Grav.24:4169-4190,2007 (arXiv:0705.4214)

• Dumitru Astefanesei, Kevin Goldstein, Rudra P. Jena, Ashoke Sen, Sandip P. Trivedi, Rotating Attractors, JHEP 0610:058,2006 (arXiv:hep-th/0606244)

• Dumitru Astefanesei, Hossein Yavartanoo, Stationary black holes and attractor mechanism, Nucl.Phys.B794:13-27,2008 (arXiv:0706.1847)

via JT gravity:

• Pranjal Nayak, Ashish Shukla, Ronak M Soni, Sandip Trivedi, V. Vishal, On the Dynamics of Near-Extremal Black Holes, J. High Energ. Phys. 2018 48 (2018) [doi:10.1007/JHEP09(2018)048, arXiv:1802.09547]

• Upamanyu Moitra, Sandip P. Trivedi, V. Vishal, Near-Extremal Near-Horizons (arXiv:1808.08239)

Actual observation

Observational signature:

• Minyong Guo, Niels A. Obers, Haopeng Yan, Observational signature of near-extremal Kerr-like black holes in a modified gravity theory at the Event Horizon Telescope, Phys. Rev. D 98, 084063 (2018) (arXiv:1806.05249)

Actual observation:

• Xinyu Dai, Shaun Steele, Eduardo Guerras, Christopher W. Morgan, Bin Chen, Constraining Quasar Relativistic Reflection Regions and Spins with Microlensing (arXiv:1901.06007)

  exposition in:

  Chandra Observatory, Chandra Views Spinning Black Holes Across Cosmic Sea, July 5 2019