Disclinations Modify Photon Motion Around Charged Black Holes in Bopp-Podolsky Electrodynamics

The behaviour of light and matter around black holes provides a crucial testing ground for theories of gravity, and recent research delves into the complex interplay of electromagnetic fields, spacetime geometry, and quantum effects near these enigmatic objects. Faizuddin Ahmed from Royal Global University, Ahmad Al-Badawi from Al-Hussein Bin Talal University, Abdelmalek Bouzenada from Echahid Cheikh Larbi Tebessi University, and colleagues investigate a specific type of black hole, a charged, rotating solution within the framework of Bopp-Podolsky electrodynamics, to understand how these factors influence its properties.

The team meticulously traces the paths of photons and massless scalar fields within the black hole’s gravitational field, revealing how the black hole’s charge, rotation, and the strength of the electromagnetic field combine to shape their trajectories. Importantly, the researchers also incorporate the Generalized Uncertainty Principle, a modification of quantum mechanics, to predict a suppression of Hawking radiation and the potential formation of stable black hole remnants, offering new insights into the ultimate fate of these cosmic objects and potentially observable signatures for modified gravity theories.

Light Orbits and Strong Gravity Tests

The search for a complete understanding of gravity remains one of the most compelling challenges in modern physics, with black holes serving as crucial testing grounds for theoretical predictions. These extreme objects, predicted by Einstein’s General Relativity, warp spacetime so intensely that nothing, not even light, can escape their pull. Recent advancements, such as the imaging of supermassive black holes, have opened new avenues for probing the behavior of light in these strong gravitational fields, demanding increasingly sophisticated theoretical models. Understanding how light orbits and bends around black holes is essential for interpreting astronomical observations and verifying the predictions of General Relativity.

While initial models of gravitational lensing assumed weak gravitational fields, the extreme conditions near black holes require a more complete treatment. Researchers have long studied how light deflects around black holes, with early work focusing on calculating deflection angles and predicting image formation. More recent investigations explore the formation of multiple images and the magnification effects caused by strong gravitational lensing, providing crucial insights for interpreting observations and testing the limits of General Relativity. Three-dimensional black holes, known as BTZ black holes, provide a simplified yet powerful framework for exploring fundamental questions in gravity and quantum physics.

Discovered in 1992, these solutions to Einstein’s equations possess unique properties that make them ideal for studying concepts like quantum gravity and the relationship between gravity and quantum field theory. Researchers have extended these solutions by incorporating various theoretical frameworks, including nonlinear electrodynamics and modified gravity theories, leading to charged black hole models with intriguing thermodynamic properties. Recent investigations focus on the influence of topological defects, known as disclinations, on the spacetime around these black holes. These defects introduce unique distortions in spacetime, altering the paths of light and influencing the behavior of matter. By studying how light and scalar fields propagate in these distorted spacetimes, and by applying principles from quantum gravity like the Generalized Uncertainty Principle, researchers aim to understand how these defects might affect the stability of black holes and potentially lead to the formation of stable remnants. This work could reveal distinctive observational signatures that could be used to test modified gravity theories in the strong-field regime, pushing the boundaries of our understanding of gravity and the universe.

Photon Paths Around Charged, Disclinated Black Holes

Researchers employed a multifaceted approach to investigate the behaviour of spacetime around compact objects, beginning with a detailed analysis of photon motion within a specific three-dimensional black hole solution. This solution, incorporating both electric charge and a cosmological constant, was further complicated by the introduction of ‘disclinations’, topological defects that alter the geometry of spacetime, allowing for a more nuanced exploration of gravitational effects. The team avoided simplified approximations, focusing on a rigorous treatment of how light rays travel in this complex environment, charting their paths to understand how the black hole’s properties and the presence of disclinations influence their trajectories. Extending beyond photon behaviour, the research incorporated wave dynamics by solving the Klein-Gordon equation to model the propagation of massless scalar fields.

A key innovation involved transforming this equation into a Schrödinger-like form, effectively creating an ‘effective potential’ that encapsulates the combined influence of the topological defect and electromagnetic corrections on the wave’s behaviour. This allowed researchers to predict how scalar fields would be affected by the black hole’s unique spacetime geometry, providing insights into potential observational signatures. The methodology also ventured into the realm of quantum gravity by applying the Generalized Uncertainty Principle (GUP), a theoretical framework that modifies the standard Heisenberg uncertainty principle at extremely small scales. By incorporating the GUP, the team derived a corrected Hawking temperature for the black hole, revealing a suppression of thermal radiation that could potentially lead to the formation of stable black hole remnants, challenging conventional expectations about black hole evaporation. Finally, to further characterise orbital dynamics, researchers calculated Keplerian frequencies for circular orbits, demonstrating how the interplay between charge, nonlinear electrodynamics, and disclination parameters creates distinctive observational signatures that could be used to test modified gravity theories in strong gravitational fields.

Disclinations and Charge Modify Black Hole Geometry

Researchers have investigated the behavior of black holes in three dimensions, focusing on solutions similar to the well-known BTZ black hole, but with modifications accounting for both electric charge and the presence of disclinations, defects in spacetime geometry. These investigations reveal how fundamental parameters, including black hole mass, electric charge, cosmological constant, and a coupling parameter related to a specific type of electrodynamics, influence the motion of particles and waves around the black hole. The study demonstrates that these parameters collectively shape the gravitational landscape, affecting the orbits of photons and the propagation of scalar fields. The team explored how the introduction of disclinations alters the standard BTZ solution, creating a more complex spacetime geometry.

Analysis of null and timelike geodesics, the paths of massless and massive particles, revealed conditions for stable circular orbits, demonstrating how the interplay between charge, electrodynamics, and disclination parameters can create unique observational signatures. This suggests potential avenues for testing modified gravity theories in extreme gravitational environments, as the orbital characteristics deviate from those predicted by classical general relativity. Furthermore, the researchers examined the propagation of massless scalar fields, fundamental particles that mediate forces, by transforming the governing equation into a form resembling the Schrödinger equation used in quantum mechanics. This allowed them to identify an effective potential that dictates how waves behave in the curved spacetime around the black hole, providing insights into the interaction between gravity and quantum fields.

Extending this analysis to the realm of quantum gravity, the team applied the Generalized Uncertainty Principle (GUP), a theoretical framework that incorporates quantum effects into gravity. The results demonstrate that GUP corrections lead to a suppression of Hawking radiation, the thermal emission from black holes, potentially preventing complete evaporation and suggesting the possibility of stable black hole remnants. This finding has significant implications for resolving the information paradox, a long-standing problem in theoretical physics concerning the fate of information that falls into a black hole. Finally, calculations of the Keplerian frequency, the rate at which objects orbit in a circular path, reveal how the interplay of these parameters dynamically influences orbital motion, providing further observational signatures that could distinguish this modified black hole model from standard predictions.

Black Hole Geometry, Disclinations, and Thermal Properties

This research investigates the geometry around black holes within a specific theory combining gravity and electromagnetism, and explores how topological defects influence this spacetime. The authors derive a black hole solution that incorporates both electric charge and the presence of disclinations, geometric defects analogous to cosmic strings, and then analyze the motion of light and massless scalar fields within this spacetime. Their analysis reveals how parameters such as the black hole’s mass, charge, a cosmological constant, and the strength of the coupling affect the paths of these particles. Furthermore, the study examines the thermal properties of these black holes by applying the Generalized Uncertainty Principle, which suggests a suppression of Hawking radiation and the potential for stable black hole remnants. By calculating Keplerian frequencies for circular orbits, the researchers demonstrate that the interplay between charge, nonlinear electrodynamics, and disclination parameters creates unique observational signatures. The results indicate that these signatures could, in principle, be used to test modified gravity theories in strong gravitational fields.