A5100603348- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Astrophysics and Cosmic Phenomena
- Relativity and Gravitational Theory
- Quantum Mechanics and Applications
- Quantum Information and Cryptography
- Noncommutative and Quantum Gravity Theories
- Quantum Electrodynamics and Casimir Effect
- Galaxies: Formation, Evolution, Phenomena
- Advanced biosensing and bioanalysis techniques
- Working Capital and Financial Performance
- Food Drying and Modeling
- Experimental and Theoretical Physics Studies
- Particle physics theoretical and experimental studies
- Advanced Frequency and Time Standards
- Neural and Behavioral Psychology Studies
- Laser-Plasma Interactions and Diagnostics
- MXene and MAX Phase Materials
- Quantum optics and atomic interactions
- Seed and Plant Biochemistry
- Advanced Differential Geometry Research
- History and Developments in Astronomy
- Advanced Biosensing Techniques and Applications
University of Arizona
2024-2025
University of KwaZulu-Natal
2017-2023
Forest Research Institute
2023
Indian Institute of Technology Kanpur
2023
National Institute of Technology Patna
2021-2023
University of Glasgow
2023
Dr. B. R. Ambedkar National Institute of Technology Jalandhar
2022
Jamia Millia Islamia
2017-2022
Peoples' Friendship University of Russia
2022
All-Russian research Institute of metrological service
2022
Horizon-scale images of black holes (BHs) and their shadows have opened an unprecedented window onto tests gravity fundamental physics in the strong-field regime. We consider a wide range well-motivated deviations from classical General Relativity (GR) BH solutions, constrain them using Event Horizon Telescope (EHT) observations Sagittarius A$^*$ (Sgr A$^*$), connecting size bright ring emission to that underlying shadow exploiting high-precision measurements Sgr A$^*$'s mass-to-distance...
Recently there has been a surge of interest in regularizing, D → 4 limit of, the Einstein-Gauss-Bonnet (EGB) gravity, and resulting regularized 4D EGB gravity nontrivial dynamics. The theory admits spherically symmetric black holes generalizing Schwarzschild holes. We consider rotating hole discuss their horizon properties shadow cast. effects GB coupling parameter on shape size shadows are investigated context recent M87* observations from EHT . Interestingly, for given spin parameter,...
Recently, a non-trivial $4D$ Einstein-Gauss-Bonnet (EGB) theory of gravity, by rescaling the GB coupling parameter as $\alpha/(D-4)$, was formulated in \cite{Glavan:2019inb}, which bypasses Lovelock's theorem and avoids Ostrogradsky instability. The admits static spherically symmetric black hole, unlike $5D$ EGB or general relativity counterpart, can have both Cauchy event horizons. We generalize previous work, on gravitational lensing Schwarzschild strong weak deflection limits to holes...
The Event Horizon Telescope (EHT), a global submillimeter wavelength very long baseline interferometry array, unveiled event-horizon-scale images of the supermassive black hole M87* as an asymmetric bright emission ring with diameter $ 42 \pm 3\; \mu$as, and it is consistent shadow Kerr general relativity. A also solution some alternative theories gravity, while several modified gravity admit non-Kerr holes. While earlier estimates for mass, depending on method used, fall in range \approx...
The nonminimal coupling of the nonzero vacuum expectation value self-interacting antisymmetric Kalb-Ramond field with gravity leads to a power-law hairy black hole having parameter $s$, which encompasses Reissner-Nordstrom ($s=1$). We obtain axially symmetric counterpart this solution, namely, rotating hole, encompasses, as special cases, Kerr ($s=0$) and Kerr-Newman ($s=1$) holes. Interestingly, for set parameters ($M$, $a$, $\mathrm{\ensuremath{\Gamma}}$), there exists an extremal...
The recently obtained hairy Kerr black holes, due to additional sources or surrounding fluid, like dark matter, with conserved energy-momentum tensor, have a deviation $\alpha$ and primary hair $l_0$, apart from rotation parameter $a$ mass $M$. In the wake of \textit{Event Horizon Telescope} (\textit{EHT}) observations supermassive hole M87*, recent surge in interest shadows suggests comparing holes general relativity (GR) modified theories gravity (MoG) assess these models' differences....
Simpson-Visser (SV) spacetimes are the simplest globally regular modifications of Schwarzschild, Reissner-Nordsr\"om and other black hole solutions general relativity. They smoothly interpolate between these holes traversable wormholes. After a brief presentation Schwarzschild-like Reissner-Nordsr\"om-like SV geometries, including their Carter-Penrose diagrams, we show that any static, spherically symmetric metric can be obtained as an exact solution to Einstein field equations sourced by...
We discuss the horizon properties, shadow cast, and weak gravitational lensing of charged rotating regular black holes, which in addition to mass ($M$) rotation parameter ($a$) have an electric charge ($Q$) magnetic ($g$). The considered holes are generalization Kerr ($Q=g=0$) Kerr-Newman ($g=0$) holes. Interestingly, for a given set, apparent size monotonically decreases gets more distorted with increasing $Q$. put constraints on hole parameters aid recent M87* observation. conserved...
Abstract In recent times there is a surge of interest in constructing Einstein–Gauss–Bonnet (EGB) gravity, the limit D → 4, -dimensional EGB gravity. Interestingly, static spherically symmetric solutions various proposed 4 regularized gravities coincide, and incidentally some other theories also admit same solution. We prove theorem that characterizes large family nonstatic or radiating to representing, general, type II fluid. An extension theorem, given without proof as being similar...
Abstract The Event Horizon Telescope (EHT) observation unveiled the first image of supermassive black hole Sgr A* showing a shadow diameter θ sh = 48.7 ± 7 μ as with fractional deviation from Schwarzschild <?CDATA $\delta =-{0.08}_{-0.09}^{+0.09}\,(\mathrm{VLTI}),-{0.04}_{-0.10}^{+0.09}\,(\mathrm{Keck})$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>δ</mml:mi> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>0.08</mml:mn>...
Abstract A mathematically consistent rotating black hole model in loop quantum gravity (LQG) is yet lacking. The scarcity of solutions LQG substantially hampers the development testing from observations, e.g., Event Horizon Telescope (EHT) observations. EHT observation revealed event horizon-scale images supermassive holes Sgr A* and M87*. results are with shadow a Kerr general relativity. We present LQG-motivated (LMRBH) spacetimes, which regular everywhere asymptotically encompass as...
Loop quantum gravity inspired partial polymer quantization in four-dimensional spacetime leads to a globally regular black hole with single horizon. The polymerized metric is characterized by the minimum length parameter $k$, and mimics Schwarzschild weak-field limit. We present an analytic numerical investigation of strong gravitational lensing shadow morphology determine observational impacts effects. Interestingly, light deflection angle, angular separation between outermost relativistic...
We obtain exact Bardeen black holes to the regularized $4D$ Einstein--Gauss--Bonnet (EGB) gravity minimally coupled with nonlinear electrodynamics (NED). In turn, we analyze horizon structure determine effect of GB parameter $\alpha$ on minimum cutoff values mass, $M_0$, and magnetic monopole charge, $g_0$, for existence a hole horizon. an expression thermodynamic quantities, namely, Hawking temperature $T_+$, entropy $S_+$, Helmholtz free energy $F_+$, specific heat $C_+$ associated...
The lack of rotating black holes, typically found in nature, hinders testing modified gravity from astrophysical observations. We present the axially symmetric counterpart an existing spherical hairy hole Horndeski having additional deviation parameter $Q$, which encompasses Kerr as a particular case ($Q=0$). investigate effect $Q$ on holes' geometry and analytically deduce gravitational deflection angle light weak-field limit. For S2 source star, for Sgr A* model both prograde retrograde...
Rotating black hole solutions in theories of modified gravity are important as they offer an arena to test these through astrophysical observation. The non-rotating can be hardly tested since the spin is very any process. We present rotating counterpart a recently obtained spherically symmetric exact solution surrounded by perfect fluid context Rastall theory, viz, that generalize Kerr–Newman solution. In turn, we analyze specific cases holes matter like dust and quintessence fields....
In the Einstein-Maxwell theory with nonlinear electrodynamics (NED) fields, singularity problem in general relativity is potentially resolved, leading to regular black hole solutions. NED theories, photons follow null geodesics of an effective geometry that differs from spacetime itself. This raises important question: Do fields produce unique observational signatures electromagnetic spectrum can test holes and theories? We analyze shadows two NED-charged their horizonless ultracompact...
Abstract Among the higher curvature gravities, most extensively studied theory is so-called Einstein–Gauss–Bonnet (EGB) gravity, whose Lagrangian contains Einstein term with GB combination of quadratic terms, and yields nontrivial gravitational dynamics in $$ D\ge 5$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>D</mml:mi> <mml:mo>≥</mml:mo> <mml:mn>5</mml:mn> </mml:mrow> </mml:math> . Recently there has been a surge interest regularizing, D \rightarrow 4...