arXiv2026
We study the correspondence between quasinormal modes (QNMs) and grey-body factors (GBFs) of higher-dimensional Reissner--Nordström black holes. Considering scalar, vector, and tensor gravitational perturbations, we systematically compute the QNMs and GBFs for each spacetime dimension and set of black-hole parameters to evaluate the analytical formula connecting them. QNMs are obtained by the continued fraction and the integration-through-midpoints methods depending on the singularity structure in the Frobenius series. We compare the GBFs determined by the correspondence using QNMs with those computed numerically. The correspondence performs well for scalar($+$), vector($+$), vector($-$), and tensor perturbations. For the scalar($-$) perturbation, the GBFs obtained by the correspondence deviate noticeably from the accurate GBFs for black holes with low to intermediate values of the charge in $D>6$. The correspondence recovers reasonable accuracy at higher charges, although the effective potential exhibits double peaks, contrary to the assumption underlying the Wentzel--Kramers--Brillouin (WKB)-based derivation of the correspondence. Whereas the accuracy decreases with increasing $D$ for other perturbation types, the correspondence for the scalar($-$) perturbation yields more accurate GBFs in $D=8$ than those in $D=7$. For near-extreme black holes, the correspondence offers a reliable approximation of GBFs for the vector($-$) perturbation, even though a double-peak potential occurs in $D>6$. These results suggest that the correspondence has a wider range of applicability than might be expected from the assumption of the WKB approach.