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Hari Prasad Saikia

Publications and source records attributed to Hari Prasad Saikia.

2 recordsLinked to original sources

Dynamics of Geodesics in Non-linear Electrodynamics Corrected Black Hole and Shadows of its Rotating Analogue

We study the nature of particle geodesics around a non-linear electrodynamic black hole (NLED-BH) inspired by the confinement of a heavy quark-antiquark system, which reduces to Maxwell's linear electrodynamics theory at the strong field regime. The corrected BH solution is a special generalisation of the Schwarzschild BH at the linear regime. Such a type of corrected system is parameterised by a charge parameter along with a non-linear electrodynamic term $ζ$. To be specific, we studied the geodesic behaviour of massless null particles through the geodesic equations using the backward ray-tracing method. We also investigated how NLED effects in charged BH spacetimes affect timelike particle orbits, specifically properties like precession frequency and orbital velocity around the NLED BH. Furthermore, to extend the analysis to the rotating case, we used the modified Newman-Janis algorithm to generate the rotating analogue of the NLED BH. We then analysed the ergosphere formation and shadow cast by the rotating analogue of the NLED BH.

gr-qc↗

Frolov Black Hole Surrounded by Quintessence - II: Quasinormal Modes, Greybody Factors, Deflection Angle and Chaos Bound

In this work, we have examined the scalar quasinormal modes, greybody factors, weak gravitational lensing, and the chaos bound of a Frolov black hole surrounded by a quintessence field. We studied the quasinormal frequencies and deduced that an increase in the value of the quintessence parameter $c$ dissipates the oscillatory behavior and thus slow down the decay of perturbations. The greybody factors are highly dependent on the multipole moment $l$ and BH parameters, with a larger $q$ hindering the transmission and smaller $α_0$ making the barrier steeper. The deflection angle of weak lensing under thin lens approximation, monotonically decreases as the value of impact parameter $b$ increases, and is visibly affected by the parameter $c$, and that $α_0$ and $q$ has very minimal effect. Lastly, we investigated the chaos bound behaviour of photon trajectories in the near-horizon neighbourhood, which indicates that it is satisfied for bigger circular photon orbits but broken for smaller ones, with high-angular-momentum photons being chaotic. This violation of the bound points towards the role of quintessence in modifying the thermodynamic features of the BH, with possible adjustments to the standard Bekenstein-Hawking entropy.

gr-qc↗