NHEK:near horizon geometry of extreme Kerr Taking the high spin limit入→O, T-嘉，R-，=- M we get the NEHK geometryJ.M.Be G.T.HroM0 ds2 =2MT(0) (-Rar+e+ar+A2o(d0+an where the polar functions are T(0)= 1+cos20 2sin0 2 A(0)= 1+cos20' Obviously it has enhanced SL(2,R)x U(1)symmetry. 口◆4回t1三1声，￥99C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NHEK: near horizon geometry of extreme Kerr Taking the high spin limit λ → 0, T = ˆt 2M λ 2/3 , R = ˆr −ˆr+ M λ −2/3 , Φ = ϕˆ − ˆt 2M , we get the NEHK geometryJ. M. Bardeen and G.T. Horowitz 9905099 ds2 = 2M2Γ(θ) ( −R 2 dT2 + dR2 R2 + dθ 2 + Λ2 (θ)(dΦ + RdT) 2 ) , where the polar functions are Γ(θ) = 1 + cos2 θ 2 , Λ(θ) = 2 sin θ 1 + cos2 θ . Obviously it has enhanced SL(2, R) × U(1) symmetry