Long-lived quasinormal modes, shadows and particle motion in four-dimensional quasi-topological gravity
- 1University of Hradec Králové
Abstract
We investigate massive scalar perturbations and several characteristics of particle motion in the spacetime of regular black holes arising in four-dimensional quasi-topological gravity. Quasinormal modes are computed using high-order WKB approximations with Padé resummation and verified through time-domain integration. For moderate values of the scalar-field mass, the time-domain profiles confirm the WKB results with excellent accuracy. As the mass increases, the damping rate decreases substantially, indicating the approach to the quasi-resonant regime of long-lived modes. For sufficiently large masses, the late-time signal becomes dominated by oscillatory power-law tails, which mask the quasi-resonant mode in the time-domain profile. In addition, we analyze photon motion and circular geodesics, including the photon-sphere radius, shadow size, Lyapunov exponent, and ISCO characteristics. These quantities exhibit only moderate deviations from their Schwarzschild values, unlike the Hawking temperature of the black hole.
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BibTeX
@article{lutfuoglu2026longlived,
title = {{Long-lived quasinormal modes, shadows and particle motion in four-dimensional quasi-topological gravity}},
author = {Bekir Can Lütfüoğlu},
journal = {The European Physical Journal C},
year = {2026},
month = may,
doi = {10.1140/epjc/s10052-026-15807-9},
url = {https://doi.org/10.1140/epjc/s10052-026-15807-9},
note = {CC BY},
}
RIS
TY - JOUR
TI - Long-lived quasinormal modes, shadows and particle motion in four-dimensional quasi-topological gravity
AU - Bekir Can Lütfüoğlu
PY - 2026
DA - 2026/05/14
JO - The European Physical Journal C
DO - 10.1140/epjc/s10052-026-15807-9
UR - https://doi.org/10.1140/epjc/s10052-026-15807-9
AB - We investigate massive scalar perturbations and several characteristics of particle motion in the spacetime of regular black holes arising in four-dimensional quasi-topological gravity. Quasinormal modes are computed using high-order WKB approximations with Padé resummation and verified through time-domain integration. For moderate values of the scalar-field mass, the time-domain profiles confirm the WKB results with excellent accuracy. As the mass increases, the damping rate decreases substantially, indicating the approach to the quasi-resonant regime of long-lived modes. For sufficiently large masses, the late-time signal becomes dominated by oscillatory power-law tails, which mask the quasi-resonant mode in the time-domain profile. In addition, we analyze photon motion and circular geodesics, including the photon-sphere radius, shadow size, Lyapunov exponent, and ISCO characteristics. These quantities exhibit only moderate deviations from their Schwarzschild values, unlike the Hawking temperature of the black hole.
SN - 1434-6044
SN - 1434-6052
ER -