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Shadows of a Non-Commutative Black Hole under the Influence of a Magnetized Plasma

Mrinnoy M. Gohain, Kalyan Bhuyan, Paragjyoti Chutia

TL;DR

This work analyzes how a non-commutative spacetime with a smeared mass distribution affects BH shadows when the BH is surrounded by axion-plasmon magnetized plasma. By combining a Hamiltonian treatment of photon propagation in a dispersive plasma with the NC lapse function, the authors compute photon-sphere radii and shadow observables for homogeneous and inhomogeneous plasmas, and derive constraints from the Event Horizon Telescope observation of Sgr A*. The results show that the NC parameter $\theta$ dominantly shapes the photon sphere and shadow, while axion-plasmon and magnetic-field parameters mostly alter the shadow subtly, depending on plasma density; energy-emission rates also track these dependencies, with stronger effects in the homogeneous plasma. Overall, the work provides a framework to test non-commutative gravity and axion-plasmon physics against BH-shadow observations and BH-evaporation signatures.

Abstract

We investigate the properties of the shadow cast by a black hole (BH) in a non-commutative spacetime surrounded by a plasma medium. BHs in a plasma environment can exhibit complex interactions that profoundly affect their shadow properties. In specific terms, we consider a special type of plasma medium motivated from the interactions among axions, photons and plasma excitations, or commonly termed as axion-plasmon in the presence of a magnetic field. We have studied the effect of these plasma parameters and the non-commutative parameter on the shadow properties by focusing particularly on the photon sphere radius, angular shadow and the shadow observed from the observer's perspective. For this we have considered two different forms of plasma, viz homogeneous and inhomogeneous plasma. In this work we have presented the parameter dependence of these BH shadow properties. Finally, we have also studied the energy emission rate of the BH and how it depends on the model and plasma parameters.

Shadows of a Non-Commutative Black Hole under the Influence of a Magnetized Plasma

TL;DR

This work analyzes how a non-commutative spacetime with a smeared mass distribution affects BH shadows when the BH is surrounded by axion-plasmon magnetized plasma. By combining a Hamiltonian treatment of photon propagation in a dispersive plasma with the NC lapse function, the authors compute photon-sphere radii and shadow observables for homogeneous and inhomogeneous plasmas, and derive constraints from the Event Horizon Telescope observation of Sgr A*. The results show that the NC parameter dominantly shapes the photon sphere and shadow, while axion-plasmon and magnetic-field parameters mostly alter the shadow subtly, depending on plasma density; energy-emission rates also track these dependencies, with stronger effects in the homogeneous plasma. Overall, the work provides a framework to test non-commutative gravity and axion-plasmon physics against BH-shadow observations and BH-evaporation signatures.

Abstract

We investigate the properties of the shadow cast by a black hole (BH) in a non-commutative spacetime surrounded by a plasma medium. BHs in a plasma environment can exhibit complex interactions that profoundly affect their shadow properties. In specific terms, we consider a special type of plasma medium motivated from the interactions among axions, photons and plasma excitations, or commonly termed as axion-plasmon in the presence of a magnetic field. We have studied the effect of these plasma parameters and the non-commutative parameter on the shadow properties by focusing particularly on the photon sphere radius, angular shadow and the shadow observed from the observer's perspective. For this we have considered two different forms of plasma, viz homogeneous and inhomogeneous plasma. In this work we have presented the parameter dependence of these BH shadow properties. Finally, we have also studied the energy emission rate of the BH and how it depends on the model and plasma parameters.

Paper Structure

This paper contains 12 sections, 47 equations, 10 figures, 1 table.

Table of Contents

  1. Introduction
  2. Photon motion around the BH in the presence of axion-plasmon
  3. Existence Condition for Circular Orbits: Analytical Estimate
  4. Photon Sphere Radius
  5. Homogeneous Plasma
  6. Inhomogeneous plasma with $\omega^2_{p}(r)=\kappa/r^q$
  7. Shadows
  8. Homogeneous Plasma
  9. Inhomogeneous Plasma
  10. Observational Constraints
  11. Energy Emission from BH: Effect of Axion-Plasmon
  12. Conclusion

Figures (10)

  • Figure 1: Variation of photon sphere radius with the plasma frequency for various combinations of the parameters for a homogeneous plasma
  • Figure 2: Variation of photon sphere radius with the plasma frequency for various combinations of the parameters for an inhomogeneous plasma
  • Figure 3: Variation of angular shadow with the observer's position for various combinations of the parameters for a homogeneous plasma
  • Figure 4: Variation of angular shadow with the observer's position for various combinations of the parameters for an inhomogeneous plasma
  • Figure 5: Shadow images for various combinations of the parameters for a homogeneous plasma
  • ...and 5 more figures