Global Monopole Charge Advances Black Hole Shadow Analysis and Relativistic Imaging

The intense gravity around black holes offers a unique laboratory for testing fundamental physics, and recent research explores how these objects might behave when gravity itself is slightly altered. Bijendra Kumar Vishvakarma from Banaras Hindu University and Shubham Kala from The Institute of Mathematical Sciences, along with their colleagues, investigate the possibility of subtle violations of established physical laws by examining how light bends around a black hole possessing both a global monopole charge and characteristics predicted by ‘bumblebee gravity’, a theory suggesting Lorentz symmetry may not be absolute. The team calculates how light paths deviate near such a black hole, predicting measurable effects on gravitational lensing, the bending and magnification of light from distant objects, including the size and shape of Einstein rings and the brightness of multiple images. These calculations reveal that the black hole’s properties and the parameters of bumblebee gravity significantly change the appearance of its shadow, potentially offering astronomers a way to observe and test this intriguing modification of gravity in the strong gravitational field around black holes.

A Lorentz symmetry breaking parameter, γ, features prominently in this work. The team computes the deflection angles of light passing near a black hole in the strong deflection limit, and estimates key lensing observables, including relativistic Einstein rings, absolute magnifications, image separations, and flux ratios, for astrophysical black holes. Analysis of the black hole shadow utilises the apparent angular size, θShadow = 2 θ∞, at the limiting photon orbit. Furthermore, researchers study the modification of shadow structure in the presence of a radially infalling, optically thin accretion flow within a generalised framework. Results indicate that both the global monopole charge and Lorentz-violating parameters significantly influence the observed phenomena.

Black Hole Shadows and Gravitational Lensing

Research extensively explores gravitational lensing and black hole shadows, a core focus within general relativity and astrophysics. Scientists calculate and analyze how light bends around black holes, wormholes, and other compact objects, investigating phenomena like Einstein rings, arcs, and multiple images. These studies determine how parameters such as spin and charge affect black hole shadows, and explore whether exotic objects like wormholes can be distinguished from black holes through observation. Several papers investigate modifications to general relativity and their impact on gravitational lensing and black holes.

The Standard-Model Extension (SME) examines the effects of Lorentz violation on gravity, while other research explores alternative theories like f(R) gravity and Einstein-Gauss-Bonnet gravity, predicting their effects on lensing and black hole properties. A subset of studies delves into the thermodynamic properties of black holes and attempts to connect general relativity with quantum mechanics, calculating black hole entropy and investigating quantum corrections to classical black hole models. Researchers employ mathematical tools like the Newman-Penrose formalism and Sachs’ Theorem to study light propagation and geodesic focusing in curved spacetime. Numerical relativity, using computer simulations, models black hole mergers and gravitational waves, complementing imaging work.

Recent work, particularly from 2024-2025, demonstrates continued focus on gravitational lensing around compact objects, exploring new spacetime geometries and investigating the influence of dark matter and dark energy. A key goal is to differentiate black holes from exotic alternatives, using gravitational lensing as a tool. Precise lensing measurements test general relativity and search for deviations indicating modified gravity, while also providing insights into dark matter and dark energy. The Event Horizon Telescope’s success has spurred theoretical work predicting future observations, and combining gravitational wave data with electromagnetic observations offers a more complete understanding of astrophysical events.

Bumblebee Gravity Predicts Black Hole Shadow Size

Scientists have achieved detailed measurements of light bending around black holes within bumblebee gravity, a theory incorporating global monopole charge and Lorentz symmetry breaking. The research focuses on strong gravitational lensing, examining light path deviations in intense gravity, and provides insights into observing these effects. Experiments involved calculating deflection angles of light, allowing the team to estimate crucial lensing observables for astrophysical black holes. Results demonstrate that the apparent angular size of the black hole shadow is defined by θShadow = 2 θ∞, measured at the limiting photon orbit.

The team meticulously analyzed relativistic Einstein rings, absolute magnifications, image separations, and flux ratios, all significantly influenced by the global monopole charge and Lorentz-violating parameters. Measurements confirm that these parameters alter the photon sphere, impacting the structure and morphology of the black hole shadow. The study explored the modification of the shadow structure by incorporating a radially infalling, optically thin accretion flow, providing a more realistic model of black hole environments. This breakthrough delivers a generalized framework for understanding how these factors interact, revealing that both the global monopole charge and Lorentz-violating parameters substantially influence the lensing observables and shadow morphology. These findings offer potential observational signatures for testing bumblebee gravity in the strong-field regime, opening new avenues for probing fundamental physics with astrophysical observations.

Bumblebee Gravity Alters Black Hole Shadows

This research investigates black holes within bumblebee gravity, a theoretical framework incorporating a global monopole charge and Lorentz symmetry breaking. By calculating how light bends around these black holes, the team determined key characteristics of gravitational lensing, including the size and shape of Einstein rings and the magnification of distant objects, offering a means to observe these effects in astrophysical black holes. The results demonstrate that both the global monopole charge and the Lorentz-violating parameter significantly modify the black hole’s sphere of influence, the observed lensing effects, and the morphology of its shadow, potentially providing observable signatures to test the validity of bumblebee gravity in extreme gravitational environments. These findings are important because they explore modifications to general relativity and offer a pathway to test these modifications through astronomical observations, potentially revealing new physics beyond our current understanding of gravity.