Grey-body factors of higher dimensional regular black holes in quasi-topological theories

We study grey-body factors and Hawking radiation of higher-dimensional regular black holes arising in quasi-topological gravity. These spacetimes incorporate infinite-curvature corrections that remove the central singularity while preserving an event horizon and a well-defined semiclassical description. We show that, for all considered regular black hole models, the transmission of radiation and the corresponding Hawking evaporation are significantly suppressed compared to the singular black hole solutions of General Relativity.

💡 Research Summary

The paper investigates how higher‑dimensional regular black holes, arising in quasi‑topological gravity, modify the transmission of Hawking radiation compared with the singular solutions of General Relativity. Quasi‑topological gravity is a class of higher‑curvature theories that, despite containing arbitrary powers of the curvature tensor, yields second‑order field equations for static, spherically symmetric spacetimes. This property makes it possible to construct regular black‑hole metrics in which the curvature invariants remain finite everywhere while an event horizon persists.

Six distinct regular black‑hole families (labeled a–f) are considered. Each is characterized by a metric function (f(r)=1-r^{2}\psi(r)) where (\psi(r)) satisfies an algebraic equation (h(\psi)=\mu/r^{D-1}) with (\mu) proportional to the ADM mass and (\alpha) denoting the higher‑curvature coupling. The allowed range of (\alpha) for each model is listed, ensuring regularity at the core. Table 1 summarizes the functional forms of (\psi(r)) and Table 2 gives the associated Hawking temperature (T_{H}=f’(r_{0})/(4\pi)).

The authors study electromagnetic perturbations on these backgrounds. By separating variables in the Maxwell equations (using Feynman gauge) the problem reduces to a one‑dimensional Schrödinger‑type wave equation \