Narrow Results

Within the gauge symmetry framework, the $U_1$ symmetry of electrodynamics is violated in the presence of gravity with spacetime translational gauge symmetry in inertial frames. For a light ray, an eikonal equation with effective metric tensors is derived in the geometric-optics limit. Under these conditions, the angle of the deflection of light by the sun is calculated to be $\delta \varphi \approx 1.75^{″}$ in inertial frames without requiring a gauge condition such as ${\partial }_{\mu }{A}^{\mu }=0$. In contrast, if the theory is $U_1$ gauge invariant, one can impose the gauge condition ${\partial }_{\mu }{A}^{\mu }=0$ in the derivation of the eikonal equation. In this case, one obtains a slightly different effective metric tensor and a different angle of deflection $\delta \varphi \approx 1.52^{″}$. However, because the precision of experiments in the last century using optical frequencies has been no better than (10–20)% due to large systematic errors, one cannot unambiguously rule out the result $\delta \varphi \approx 1.52^{\prime }$. We hope that the precision of these data can be improved in order to test Yang–Mills gravity.

In this paper, we construct a Schwarzschild metric in the fractal dimension based on fractal calculus, and we study the deflection of light near the sun. It was observed that the new fractal spherically symmetric spacetime metric may describe supermassive black holes, which have been detected through various astronomical observations such as SDSS. We have discussed the deflection of light by the gravitational field of the sun. It was observed that the total deflection of light is affected by the fractal dimension. To estimate the numerical value of the fractal dimension, we have used the 2004analysis of almost 2 million VLBI observations of 541 radio sources made by 87 VLBI sites, which estimates the factor $\gamma$ based on PNN formalism. It was observed that the fractal dimension is roughly less than unity. However, our analysis showed that large bending gravity gives fractal dimensions lower than unity to some extent. We also gave a naïve idea about the emission thermal Unruh process in fractal dimension. It was observed that both the temperature and the entropy of black holes are affected by the fractal dimension, and that for low numerical values, the entropy of the black hole is enhanced.

Quantum theories of gravity help us to improve our insight into the gravitational interactions. Motivated by the interesting effect of gravity on the photon trajectory, we treat a quantum recipe concluding a classical interaction of light and a massive object such as the sun. We use the linear quantum gravity to compute the classical potential of a photon interacting with a massive scalar. The leading terms have a traditional 1/r subordinate and demonstrate a polarization-dependent behavior. This result challenges the equivalence principle; attractive and/or repulsive interactions are admissible.

In this paper, we analyze weak gravitational lensing by taking the black hole solution in Einstein Cubic gravity with the Gibbons and Werner approach. We deduce the deflection angle of light in a nonplasma and plasma medium. Firstly, we derive the Gaussian optical curvature and apply the Gauss–Bonnet theorem to find the deflection angle for the black hole spherically symmetric space–time. Additionally, we examine the graphical behavior of the deflection angle caused by the black hole in the presence of the nonplasma and plasma medium. Further, we use Einstein cubic gravity black hole geometry to discuss the quasi-periodic oscillations, effective force, and emission energy.

The principal objective of this project is to investigate the gravitational lensing by asymptotically flat black holes in the framework of Horndeski theory in weak field limits. To achieve this objective, we utilize the Gauss–Bonnet theorem to the optical geometry of asymptotically flat black holes and apply the Gibbons–Werner technique to achieve the deflection angle of photons in weak field limits. Subsequently, we manifest the influence of plasma medium on deflection of photons by asymptotically flat black holes in the context of Horndeski theory. We also examine the graphical impact of deflection angle on asymptotically flat black holes in the background of Horndeski theory in plasma medium as well as non-plasma medium.

The aim of the article to explore the effects of gravitational lensing and attraction of electromagnetic radiation in the description of the propagation of radiation nearby the atmospheres of rotating astrophysical objects.