Quasinormal modes of accelerating spacetime

We calculate the exact values of the quasinormal frequencies for massless perturbations with spin $s\leq2$ moving in pure accelerating spacetime. We use two different methods to transfer the perturbation equations into the form of hypergeometric differential equations and obtain the same quasinormal frequencies. These purely imaginary spectra are shown to be independent of the spin of the perturbation and match those of the so-called acceleration modes of accelerating black holes after taking the Minkowski limit. This implies that the acceleration modes actually originate from the pure accelerating spacetime and the appearance of black holes would deform the spectra. In addition, we calculate the quasinormal frequencies of scalar, electromagnetic and gravitational perturbations of $D$-dimensional de Sitter spacetime and compare them with previous results to verify the validity of our method.