Year: 2026
Type: preprint
Abstract: We investigate particle motion, optical observables, and linear wave propagation around a static black hole in Palatini Kalb Ramond gravity with a vanishing cosmological constant. The analysis distinguishes the conserved mass $M$ from the orbital mass $\bar{M}=M/ρ$ and isolates the radial deformation $σ^2=1-q/2$, where $q=\ell_2/(1-\ell_1)$. At fixed $\bar{M}$, the photon sphere, critical impact parameter, and innermost stable circular orbit retain their Schwarzschild values. Radial frequency ratios also preserve their Schwarzschild profiles for the same areal release and particle radii, while proper distances, infall times, and accumulated orbital angles depend on $σ$. For radial fall, the tidal eigenvalues acquire a factor $σ^{-2}$, and the instability exponent of the photon orbit scales as $σ^{-1}$. In addition, we examine light deflection in the weak and strong regimes with an explicit account of the conical asymptotics. The shadow comparison with Sgr A* and M87* exhibits a coupling degeneracy when the orbital mass and areal distance are set. Scalar, electromagnetic, and massless Dirac perturbations probe the physical metric, whereas a homogeneous axial gravitational sector with $δB_{μν}=0$ admits an exact Schwarzschild spectral map. In this sector, both oscillation and attenuation rates scale as $σ^{-1}$ at fixed $\bar{M}$. Third order WKB estimates agree with frequencies extracted from time evolution to within $0.7\%$ for the reported fundamental modes.
Source: arXiv (Cornell University)
Institution: Universidade Federal do Espírito Santo
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G5934120440, G6516500656
OpenAlex ID: W7222997647