https://doi.org/10.1140/epjc/s10052-026-15419-3
Regular Article - Theoretical Physics
Geodesics and light deflection in Schwarzschild-like spacetime from cosmology-inspired modified gravity
1
Centre for Space Research, North-West University, 2520, Potchefstroom, South Africa
2
The Institute of Mathematical Sciences, C.I.T Campus, Taramani, 600113, Chennai, India
3
National Institute for Theoretical and Computational Sciences (NITheCS), Stellenbosch, South Africa
4
Department of Physics, Hemvati Nandan Bahuguna Garhwal Central University, Srinagar, 246174, Uttarakhand, India
5
Centre for Theoretical Physics, The British University in Egypt, 11837, Cairo, Egypt
a
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Received:
27
September
2025
Accepted:
8
February
2026
Published online:
25
February
2026
Abstract
We investigate cosmology-driven modifications to Schwarzschild-like black hole spacetimes and analyze their impact on photon propagation, gravitational lensing, and shadow observation. The gravitational deflection angle is computed using the Rindler–Is-hak method, which incorporates finite-distance corrections and provides a consistent framework for non-asym-ptotically flat spacetimes. The effective potential for null geodesics exhibits a single unstable maximum corresponding to the photon sphere, and we study photon orbits classified according to the critical impact parameter into capture, escape, and unstable circular trajectories. Our analysis shows that the deflection angle decreases with increasing model parameter 
, resulting in weaker light bending compared to the Schwarzschild case. In addition, we examine the angular diameter of the black hole shadow as measured by a static observer, highlighting its dependence on the cosmological modification parameters. These results suggest that high-precision astrometric and lensing observations can place meaningful constraints on cosmology-inspired modifications to gravity, thereby linking astrophysical black holes with cosmic expansion and offering a novel probe of gravitational physics in strong-field regimes.
© The Author(s) 2026
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