Quasinormal mode frequencies of Kerr black holes from Regge trajectories

Absorption cross section of regular black holes in scalar-tensor conformal gravity

“…As suggested in Refs. [23][24][25][26][27][28][29], one can interpret resonances as the surface waves travelling around a photon sphere and damping simultaneously. Re λ n (ω) denotes the speed of circumnavigation of surface waves and Im λ n (ω) the damping of surface waves.…”

“…Again taking Eqs. ( 5), (29), and (30) into consideration, we compute the coefficients in Eqs. ( 26), (27), and (28).…”

“…Later, the connection between the surface waves and QNMs was established [23] in terms of the CAM method, where the QNMs were regarded as the resonance modes of surface waves. Moreover, the related progress was made [24][25][26][27][28][29], which provided a general proposal to derive the analytic expression of Regge frequency and thereby to work out ACSs. Incidentally, one method rather than the CAM was once proposed [30] to calculate the Regge frequency.…”

“…In this paper, we follow the way suggested in Refs. [23][24][25][26][27][28][29] but generalize it for dealing with CR BHs.…”