Singularity-free solution for charged stellar model in f(Q,T) gravity: Mass-radius behavior and stability analysis
Al Saadi S. Jasim M.K. Maurya S.K. Zergani S. Sekhmani Y.
2025World Scientific
International Journal of Geometric Methods in Modern Physics
2025
This study investigates the physical properties of singularity-free charged solution for compact stellar model within the framework of f(Q,T) gravity, where Q denotes the non-metricity scalar and T is the trace of the energy–momentum tensor. By solving the field equations under isotropic conditions with the Buchdahl metric and a realistic electric charge distribution, we derive a general stellar structure model. The electric charge q(r) starts at zero at the core, increases monotonically to the surface, and is highly sensitive to the charge coupling parameter β (decreasing with higher β) and the non-metricity parameter μ1 (increasing with higher μ1), while remaining unaffected by the matter-coupling parameter μ2. Energy density and pressure peak at the core, decreasing toward the surface, with central values rising significantly with μ1 (up to 1.03 × 1015 g/cm3 and 1.79 × 1035 Pa) and β, but dropping with μ2. The squared sound speed remains below unity, ensuring causality, with β enhancing fluid stiffness and μ2 softening it. Stability is confirmed via the adiabatic index, which exceeds 4/3 throughout, increasing with β (up to 2.31), and through the modified Tolman–Oppenheimer–Volkoff equation, where gravitational, hydrostatic, electric, and coupling forces balance to maintain equilibrium. The mass–radius (M–R) relationships, analyzed by varying β, μ1, and μ2 in the linear form f(Q,T) = μ1Q + μ2T, reveal maximum masses up to 2.78M⊙ (at 11.63 km for μ2 = 0.24), with β and μ1 increasing both mass (up to 2.59 and 2.68M⊙) and radius (up to 12.88 km), while higher μ2 reduces mass. These results align with observations of massive compact objects, including PSR J0740+6620, PSR J2215+5135, PSR J1748-2446ao, and GW190814, with radii ranging from 11.38 to 12.88 km for masses between 2 and 2.67M⊙. Our findings indicate that f(Q,T) gravity, combined with electric charge, offers a robust framework for modeling high-mass compact stars in the mass-gap, providing testable predictions for future astrophysical observations.
Compact star , exact solution, modified gravity , mass-radius relation
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Department of Mathematical, Physical Sciences College of Arts and Sciences, University of Nizwa, Nizwa 616, Oman
Center for Theoretical Physics Khazar University, 41 Mehseti Street, Baku, AZ1096, Azerbaijan
Centre for Research Impact & Outcome Chitkara University, Institute of Engineering and Technology Chitkara University, Punjab, Rajpura, 140401, India
Institute of Nuclear Physics, Ibragimova, 1, Almaty, 050032, Kazakhstan
Department of Mathematical
Center for Theoretical Physics Khazar University
Centre for Research Impact & Outcome Chitkara University
Institute of Nuclear Physics
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