Akhil Uniyal

Indian Institute of Technology Guwahati | IIT Guwahati · Department of Physics

Accretion physics has become more important recently due to the detection of the first horizon-scale images of the super-massive black holes of M\,87$^*$ and Sgr~A$^*$ by the Event Horizon Telescope (EHT). General relativistic magnetohydrodynamic (GRMHD) simulations of magnetized accretion flows onto a Kerr black hole have been used to interpret th...

In this work, we study the behavior of null geodesics within a rotating Teo wormhole spacetime in nonmagnetized pressureless plasma. The Teo wormholes are an explicit class of rotating wormholes that generalizes the static, spherically symmetric ones, initially considered by Morris and Thorne. By focusing on the dispersion relation of the plasma an...

Fundamental constants are crucial for comprehending physical mechanisms, but their measurements contain uncertainties due to experimental limitations. We investigate the impact of system temperature on these uncertainties using nearby white dwarfs observed in the Gaia Early Data Release 3 (EDR3) survey. Using the structures of these white dwarfs, w...

In this work, we have studied the behavior of null geodesics within a rotating wormhole space-time in non-magnetized pressure-less plasma. By focusing on the dispersion relation of the plasma and disregarding its direct gravitational effects, we examine how light rays traverse in the mentioned space-time. A key highlight of the work is the necessit...

We study the greybody factors, quasinormal modes, and shadow of the higher dimensional de-Sitter (dS)/anti de-Sitter (AdS) black hole spacetimes derived from the Einstein-bumblebee gravity theory within the Lorentz symmetry breaking (LSB) framework. We specifically apply the semi-analytical WKB method and the time domain approach to study the scala...

We present the properties of relativistic, inviscid, low angular momentum, advective accretion flow in the framework of modified theory of gravity. We adopt a $f(R)$ gravity model that satisfactorily mimics the asymptotically flat vacuum solutions of the Einstein's equations, where $R$ is the scalar curvature. With this, we solve the governing equa...

Various experiments and observations have led researchers to suggest different bounds on fundamental constants like the fine-structure constant and the proton-to-electron mass ratio. These bounds differ mostly due to the energy scale of the systems where the experiments are performed. In this article, we obtain bounds on these parameters in the mod...

In this paper, we explore the effect of non-linear electrodynamics (NLED) parameters and magnetic charges on various aspects of black holes, like how they bend light, how they emit radiation, and how they appear as a shadow by considering a thin accretion disk model. We initially examine the overall behavior of the photonsphere and the correspondin...

Various experiments and observations have led researchers to suggest different bounds on fundamental constants like the fine-structure constant and the proton-to-electron mass ratio. These bounds differ mostly due to the energy scale of the systems where the experiments are performed. In this article, we obtain bounds on these parameters in the mod...

We study the greybody factors, quasinormal modes, and shadow of the higher dimensional de-Sitter (dS)/ anti de-Sitter (AdS) black hole spacetimes derived from the Einstein-bumblebee gravity theory within the Lorentz symmetry breaking (LSB) framework. We specifically apply the semi-analytical WKB method and the time domain approach to study the scal...

Nonlinear interaction between the electromagnetic fields (EMF) are occurred when vacuum polarization in quantum electrodynamics (QED) happens. The field of nonlinear electrodynamics which may be resulting from this interaction could have important effects on black hole physics. In this paper, we consider the asymptotically flat black hole solution...