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SUMMARY:Extreme Black Holes: Anabasis and Accidental Symmetry - Achilleas 
 Porfyriadis (University of Crete)
DTSTART:20221125T130000Z
DTEND:20221125T140000Z
UID:TALK179111@talks.cam.ac.uk
CONTACT:Prahar Mitra
DESCRIPTION:The near-horizon region of black holes near extremality is uni
 versally AdS2-like. In this talk I will concentrate on the simplest exampl
 e of  AdS2 x S2 as the near-horizon of (near-)extreme Reissner-Nordstrom. 
 I will first explain the SL(2) transformation properties of the sphericall
 y symmetric linear perturbations of  AdS2 x S2 and show how their backreac
 tion leads to the Reissner-Nordstrom black hole. This backreaction with bo
 undary condition change is called an anabasis. I will then show that the l
 inear Einstein equation near AdS2 x S2\, with or without additional matter
 \, enjoys an accidental symmetry that may be thought of as an on-shell lar
 ge diffeomorphism of AdS2.
LOCATION:Potter room/Zoom
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