Asif Mahmood | Searcharxiv

arXiv2024

Dark Energy Compact Stars in Extended Teleparallel Gravity

This paper presents the study of dark-energy compact stars in the context of modified Rastall teleparallel gravity. It is the first time that dark energy celestial phenomena have been explored in this modified gravitational theory. Employing the torsion-based functions, $f(T)$ and $h(T)$, we analyzed their effects in a spherically symmetric spacetime chosen as the interior geometry, while using the Schwarzschild geometry as an outer spacetime. In this study, we explored various dark energy stellar properties, including dark energy pressure components, energy conditions, and equation of state components. Our findings reveal that the observed negative behavior of these stellar properties served as compelling evidence, validating the presence of dark energy in stellar configurations. Detailed investigations of the energy conditions, pressure profiles, sound speeds, TOV equation, adiabatic index, gradients, mass function, compactness, and redshift function forecasts a comprehensive assessment, affirming the acceptability and realism of the investigated stellar configuration.

gr-qc↗

arXiv2020

Strong Gravitational Lensing for Photon Coupled to Weyl Tensor in Kiselev Black Hole

The ambition of the present work is to highlight the phenomena of strong gravitational lensing and deflection angle for the photons coupling with Weyl tensor in a Kiselev black hole. Here, we have extended the prior work of Chen and Jing \cite{1} for Schwarzschild black hole to Kiselev black hole. For this purpose, the equation of motion for the photons coupled to Weyl tensor, null geodesic and equation of photon sphere in a Kiselev black hole spacetime have been formulated. It is found that the equation of motion of the photons depends not only on the coupling between photon and Weyl tensor, but also on the polarization direction of the photons. There is a critical value of the coupling parameter $α$ for existence of the marginally circular photon orbit outside the event horizon, which depends on the parameters of black hole and the polarization direction of photons. Further, the polarization directions of coupled photon and the coupling parameter $α$, both modify the features of the photon sphere, the angle of deflection and the functions $(\bar{a}$ and $\bar{b})$ for the strong gravitational lensing in Kiselev black hole spacetime. In addition to this, the observable gravitational lensing quantities and the shadows of the Kiselev black hole spacetime are presented in detail.

gr-qc↗