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Within a semiclassical framework, we investigate spherically symmetric solutions of the Einstein equations that (i) develop a trapped region within a finite time as measured by distant observers, and (ii) remain sufficiently regular at the…

General Relativity and Quantum Cosmology · Physics 2025-09-16 Swayamsiddha Maharana , Rama Vadapalli

In this study, we investigated the effects of incorporating barotropic fluids on cosmological solutions within the general relativity (GR) framework. We proposed a modified version of the barotropic fluid with the EoS, $p=\zeta _0 \rho…

General Relativity and Quantum Cosmology · Physics 2025-04-29 Rajdeep Mazumdar , Mrinnoy M. Gohain , Kalyan Bhuyan

The uniqueness and rigidity of black holes remain central themes in gravitational research. In this work, we investigate the construction of all extremal black hole solutions to the Einstein equation for a given near-horizon geometry,…

High Energy Physics - Theory · Physics 2026-02-06 Jan Gutowski , Chettha Saelim , Martin Wolf

The frozen star model provides a classical description of a regularized black hole and is based upon the idea that regularizing the singularity requires deviations from the Schwarzschild geometry which extend over horizon-sized scales, as…

General Relativity and Quantum Cosmology · Physics 2023-04-12 Ram Brustein , A. J. M. Medved , Tom Shindelman

By applying Noether symmetry methods, analytic solutions are obtained for a generalized Einstein-scalar-Gauss-Bonnet model with a $\xi(\phi)f(G)$ component. Variation with respect to the metric, supplemented by small perturbations, produces…

General Relativity and Quantum Cosmology · Physics 2025-12-15 Olga Razina , Dauren Rakhatov , Pyotr Tsyba , Emilio Elizalde

Static spherically symmetric solutions of the Einstein's field equations in isotropic coordinates representing perfect fluid matter distributions from Newtonian potential-density pairs are investigated. The approach is illustrated with…

General Relativity and Quantum Cosmology · Physics 2020-11-24 Gonzalo García-Reyes

Cosmography has been referred to as a solution to the inverse scattering problem, which is reasonable since it allows us to calculate cosmological bounds from data samplers by performing an expansion of the cosmological observables around…

General Relativity and Quantum Cosmology · Physics 2021-01-11 Cristian Zamora Munõz , Celia Escamilla-Rivera

A family of exact relativistic stellar models is described. The family generalizes Buchdahl's n=1 polytropic solution. The matter content is a perfect fluid and, excluding Buchdahl's original model, it behaves as a liquid at low pressures…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Kjell Rosquist

We provide new exact solutions to the Einstein-Maxwell system of equations which are physically reasonable. The spacetime is static and spherically symmetric with a charged matter distribution. We utilise an equation of state which is…

General Relativity and Quantum Cosmology · Physics 2015-06-12 S. D. Maharaj , P. Mafa Takisa

In this paper, we construct a viable strange star model in the framework of the equation of state, $p_r=\frac{1}{3}(\rho-4B)$, proposed in the MIT bag model, where $B$ is termed as the bag constant. Considering extreme Wood-Saxon-like…

General Relativity and Quantum Cosmology · Physics 2026-03-17 Sourav Biswas , Debadri Bhattacharjee , Pradip Kumar Chattopadhyay , Nawal H. Siddig , Euaggelos E. Zotos , Laila Abdulaziz Al-Essa

In this paper we discuss recent applications of the Smoothed Particle Hydrodynamics (SPH) method to the simulation of supersonic turbulence in the interstellar medium, as well as giving an update on recent algorithmic developments in…

Instrumentation and Methods for Astrophysics · Physics 2010-02-26 Daniel J. Price , Christoph Federrath

To seek for a singularity free model universe from a perfect fluid scalar-metric cosmology, we work in the "\emph{Emergent Cosmology}" (EC) paradigm which is a non-singular alternative for cosmological inflation. By using two methods…

General Relativity and Quantum Cosmology · Physics 2018-06-26 Mohsen Khodadi , Kourosh Nozari

In this paper, an analytic approximation method for highly nonlinear equations, namely the homotopy analysis method (HAM), is employed to solve some backward stochastic differential equations (BSDEs) and forward-backward stochastic…

Numerical Analysis · Mathematics 2018-01-25 Xiaoxu Zhong , Shijun Liao

The homotopy continuation method has been widely used in solving parametric systems of nonlinear equations. But it can be very expensive and inefficient due to singularities during the tracking even though both start and end points are…

Numerical Analysis · Mathematics 2021-04-13 Wenrui Hao , Chunyue Zheng

Recent low-redshift observations give value of the present-time Hubble parameter $H_{0}\simeq 74~\rm{km s}^{-1}\rm{Mpc}^{-1}$, roughly 10\% higher than the predicted value $H_{0}=67.4~\rm{km s}^{-1}\rm{Mpc}^{-1}$ from Planck's observations…

General Relativity and Quantum Cosmology · Physics 2020-09-25 Sirachak Panpanich , Piyabut Burikham , Supakchai Ponglertsakul , Lunchakorn Tannukij

Astrophysical black holes (BHs) are universally expected to be described by the Kerr metric, a stationary, vacuum solution of general relativity (GR). Indeed, by imaging M87$^\star$ and Sgr A$^\star$ and measuring the size of their shadows,…

General Relativity and Quantum Cosmology · Physics 2024-03-07 Prashant Kocherlakota , Luciano Rezzolla , Rittick Roy , Maciek Wielgus

A spherically symmetric charged ideal fluid solution of Einstein field equation is given in the presence of the cosmological constant and two well known example of this type of solution is presented. If the matter is confined in a region,…

General Relativity and Quantum Cosmology · Physics 2007-11-30 N. Ozdemir

A new singularity free model of anisotroipic compact star is proposed. The Einstein field equations are solved in closed form by utilizing Matese \& Whitman mass function. The model parameters $\rho$, $p_r$ and $p_t$ all are well behaved…

General Relativity and Quantum Cosmology · Physics 2016-11-01 Piyali Bhar , B. S. Ratanpal

We provide a road towards obtaining gravitational waveforms from inspiraling material binaries with an accuracy viable for third-generation gravitational wave detectors, without necessarily advancing computational hardware or…

General Relativity and Quantum Cosmology · Physics 2021-07-07 John Ryan Westernacher-Schneider

In this paper, we explore the existence of spherically symmetric strange quark configurations coupled with anisotropic fluid setup in the framework of modified Gauss-Bonnet theory. In this regard, we adopt two models such as \emph{(i)}…

General Relativity and Quantum Cosmology · Physics 2024-11-05 K. Hassan , Tayyab Naseer , M. Sharif