Quasinormal spectra, greybody factors, optical shadows, and light deflection by dyonically charged black holes in metric-affine gravity with torsion and nonmetricity
Sekhmani Y. Baruah A. Al-Badawi A. Maurya S.K. Jasim M.K. Altanji M. Gashti S.N.
February 2026Elsevier B.V.
Chinese Journal of Physics
2026#99177 - 198 pp.
This study explores the impact of the spin (κs), dilaton (κd), and shear (κsh) charges on the massless scalar quasinormal modes (QNMs), greybody factors, shadow behavior, and deflection angle of a four-dimensional dyonically charged black hole (BH) in metric-affine gravity (MAG) with torsion and nonmetricity (NMT). To assess the stability against perturbations, we analyze scalar QNMs of the BH in the frequency domain using the highly accurate 13th order Padé-averaged WKB method. Using appropriate parameter spaces, we study the influence of the spin, dilaton, and shear charges on the QNMs. The obtained frequency data indicate the stability of the BH against scalar perturbation. The frequencies generally decrease with increasing dilaton and shear charges; however, the damping rates exhibit nuanced behavior. The spin charge has the opposite effect on the QNMs in that the frequencies and damping rates increase with the spin charge consistently across the studied overtone range. Physically, it is interpreted that the additional charges effectively influence the stiffness of the spacetime and the propagation of gravitational waves. The QNMs estimated using the Padé-averaged WKB method exhibit good accuracy, and outliers in specific parameter ranges are highlighted. Next, we investigate the behavior of the deflection of light rays by dyonically charged BHs in MAG using the Gauss-Bonnet formalism. Using weak-field approximations and relevant constraints associated with the cosmological constant, we compute and analyze the optical quantities by altering the spin, dilaton, and shear charge parameters. Constraints on the spin (κs), dilaton (κd), and shear (κsh) charges, derived from Event Horizon Telescope observations of M87* and Sgr A*, highlight the fact that this BH model is a promising candidate for simulating astrophysical BHs.
Black holes , Grey body factors , Metric affine gravity , Non metricity , QNMs , Shadow
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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, 050032, Kazakhstan
Department of Mathematical and Physical Sciences, College of Arts and Sciences, University of Nizwa, P.O. Box 33, 616, Oman
Department of Physics, Albert Einstein School of Physical Sciences, Assam University, Assam, Cachar, 788011, India
Department of Physics, Al-Hussein Bin Talal University 71111, Ma’an, Jordan
Department of Mathematics, College of Sciences, King Khalid University, 61413, Saudi Arabia
School of Physics, Damghan University, P. O. Box 3671641167, Damghan, Iran
Center for Theoretical Physics
Centre for Research Impact & Outcome
Institute of Nuclear Physics
Department of Mathematical and Physical Sciences
Department of Physics
Department of Physics
Department of Mathematics
School of Physics
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