arXiv subjects

Santosh V Lohakare

Publications and source records attributed to Santosh V Lohakare.

6 recordsLinked to original sources

arXiv2023

Cosmological models in $f (T, \mathcal{T})$ gravity and the dynamical system analysis

The study addresses matter-coupled modified gravity, particularly $f (T, \mathcal{T})$ gravity, unveiling distinct formalism. The research further discusses stability analysis, and the dynamical system approach, exploring the dynamics of critical points to understand these models' viability better. The dynamical system analysis of the cosmological models in $f(T, \mathcal{T})$ gravity, where $T$ and $\mathcal{T}$ respectively represent the torsion scalar and trace of the energy-momentum tensor has been investigated. It demonstrates how first-order autonomous systems can be treated as cosmological equations and analyzed using standard dynamical system theory techniques. Two forms of the function $f(T,\mathcal{T})$ are considered (i) one with the product of trace and higher order torsion scalar and the other (ii) linear combination of linear trace and squared torsion. By employing this methodology, the research aims to uncover the actual behavior of the Universe. The findings emphasize the graphical representation of these insights, enriching our understanding of cosmological scenarios.

gr-qc↗

arXiv2023

Dynamical Complexity in Teleparallel Gauss-Bonnet Gravity

The stable critical points and their corresponding cosmology are derived in the teleparallel gravity with an added Gauss-Bonnet topological invariant term. We have analyzed the dynamics of the Universe by presenting two cosmological viable models, showing the potential to describe different phases of the evolution of the Universe. The value of the deceleration parameter ($q$), total equation of state parameter ($ω_{tot}$) and dark energy equation of state parameter ($ω_{DE}$) have been presented against each critical point. The existence and stability conditions are also presented. We study the behavior of the phase space trajectories at each critical point. Finally, the evolutionary behavior of the deceleration parameter and the equation of state parameters have been assessed with the initial condition of the dynamical variables, and compatibility has been observed in connection with the present cosmological scenario.

gr-qc↗

arXiv2023

The Fate of the Universe Evolution in the Quadratic Form of Ricci-Gauss-Bonnet Cosmology

We investigate the possibility of future singularity due to the accelerating expansion of the Universe. It has been found that the gravitational theory comprises Ricci scalar $R$ and Gauss-Bonnet invariant $\mathcal{G}$, known as $F(R,\mathcal{G})$ gravity, which can be viewed in the quadratic form. Three models are presented using Hubble parameters to represent a finite and infinite future. The parameters of the models are analyzed on the basis of their physical and geometrical properties. This study also explores the properties of the modified gravitational theory, and neither the future singularity nor the little or pseudo rip is posed as threats to the fate of the Universe. We present scalar perturbation approaches to perturbed evolution equations and demonstrate their stability.

gr-qc↗

arXiv2022

Bouncing cosmology in modified gravity with higher-order Gauss-Bonnet curvature term

In this paper, we have studied the bouncing behavior of the cosmological models formulated at the background of the Hubble function in the F(R, G) theory of gravity, where R and G denote the Ricci scalar and Gauss-Bonnet invariant. The actions of bouncing cosmology are studied under consideration of different viable models and can resolve the difficulty of singularity in standard Big-Bang cosmology. Both models show bouncing behavior and satisfy the bouncing cosmological properties. Models based on dynamical, deceleration, and energy conditions indicate the accelerating behavior at the late evolution time. Phantom at the bounce epoch is analogous to a quintessence behavior. Finally, we formulate the perturbed evolution equations and investigate the stability of two bouncing solutions.

gr-qc↗

arXiv2022

Anisotropic Strange Star Model Beyond Standard Maximum Mass Limit by Gravitational Decoupling in $f(Q)$ Gravity

The current theoretical development identified as the gravitational decoupling via Complete Geometric Deformation (CGD) method that has been introduced to explore the nonmetricity $Q$ effects in relativistic astrophysics. In the present work, we have investigated the gravitationally decoupled anisotropic solutions for the strange star in the framework of $f(Q)$ gravity by utilizing the CGD technique. To do this, we started with Tolman metric ansatz along with the MIT Bag model equation of state related to the hadronic matter. The solutions of the governing equations of motions are obtained by using two approaches, namely the mimicking of the $θ$ sector to the seed radial pressure and energy density of the fluid model. The obtained models describe the self-gravitating static, compact objects whose exterior solution can be given by the vacuum Schwarzschild Anti-de Sitter spacetime. In particular, we modeled five stellar candidates, viz., LMC X-4, PSR J1614-2230, PSR J0740+6620, GW190814, and GW 170817 by using the observational data. The rigorous viability tests of the solutions have been performed through regularity and stability conditions. We observed that the nonmetricity parameter and decoupling constant show a significant effect on stabilizing to ensure the physically realizable stellar models. The innovative feature of this work is to present the stable compact objects with the masses beyond the $2 M_{\odot}$ without engaging of exotic matter. Therefore, the present study shows a new perception and physical significance about the exploration of ultra-compact astrophysical objects.

gr-qc↗

arXiv2022

Dynamical Stability Analysis of Accelerating f(T) Gravity Models

In this paper, we have emphasized the stability analysis of the accelerating cosmological models obtained in $f(T)$ gravity theory. The behavior of the models based on the evolution of the equation of state parameter shows phantom-like behavior at the present epoch. The scalar perturbation technique is used to create the perturbed evolution equations, and the stability of the models has been demonstrated. Also, we have performed the dynamical system analysis for both the models. In the two specific $f(T)$ gravity models, three critical points are obtained in each model. In each model, at least one critical point has been observed to be stable.

gr-qc↗