Quasinormal modes in near-extremal spinning C-metric

We investigate the quasinormal modes of the spinning C-metric with a massless scalar field conformally coupled with gravity. Conformal transformation is employed to separate and subsequently solve the massless scalar field equations. As the outer and acceleration horizons approach each other, the potential term of the field equation is reduced to the Pöshl-Teller potential because the acceleration horizon is similar to the cosmological horizon of de Sitter spacetime. Finally, we obtain the analytical quasinormal frequency at which the decay rate is quantized.