Year: 2026
Type: preprint
Abstract: Accretion disk surrounding around compact astrophysical objects serve as a powerful laboratories for testing gravitational theories in the strong-field regimes. In this work, we systematically investigated the structural, dynamical, and thermodynamic properties of the steady-state thin accretion disk within the framework of $f(R,T)$ gravity by adopting the linear functional form $f(R,T) = R + 2χT$ coupled with the pressure-free dust fluid matter Lagrangian ($\mathcal{L}_m = -ρ$). We demonstrate that the modified field equations seamlessly reduce to standard General Relativity in the pure vacuum limit ($T_{μν} = 0$). Utilizing a perturbative approach for a small coupling parameter ($\vert{}χ\vert{} \ll 1$), we derive the first-order corrections to the background Schwarzschild metric potentials, which subsequently govern the modified particle kinematics, the specific energy $E$, the specific angular momentum $L$, and the Keplerian angular velocity $Ω$. Our analysis reveals that the geometry-matter coupling parameter $χ$ significantly shifted towards the location of the Innermost Stable Circular Orbit ($r_{isco}$) and alters the radial energy dissipation rate $F(r)$ and the effective surface temperature profile $T(r)$ across the Shakura-Sunyaev thin disk. Furthermore, the resulting modifications in the Spectral Energy Distribution (SED) and overall radiative efficiency $η$ provide robust theoretical signature.
Source: arXiv (Cornell University)
Author: Shekh, S. H.
Institution: Pacif Institute of Cosmology and Selfology
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7214617285