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We study static, spherically symmetric black hole solutions of the Einstein equations with a positive cosmological constant and a conformally coupled self interacting scalar field. Exact solutions for this model found by Mart{\'\i}nez,…

High Energy Physics - Theory · Physics 2008-11-26 Gustavo Dotti , Reinaldo J. Gleiser , Cristian Martinez

Aims: In the present work we search for a new model of compact star within embedding class one spacetime i.e., four dimensional spacetime embedded in five dimensional Pseudo Euclidean space. Methods: In particular we propose a new mass…

General Physics · Physics 2017-10-11 S. K. Maurya , Y. K. Gupta , Farook Rahaman , Monsur Rahaman , Ayan Banerjee

The purpose of this paper is to further investigate the solution space of self-similar spherically symmetric perfect-fluid models and gain deeper understanding of the physical aspects of these solutions. We achieve this by combining the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 B. J. Carr , A. A. Coley , M. Goliath , U. S. Nilsson , C. Uggla

Context: The Circular Restricted Three-Body Problem provides a fundamental framework for understanding resonant dynamics in binary star systems. Aims: We develop a unified Hamiltonian formulation for mean-motion resonances that encompasses…

Earth and Planetary Astrophysics · Physics 2026-05-08 R. Capuzzo-Dolcetta

In this article we propose a new class of isotropic strange star using Buchdahl-I metric ansatz in the context of MIT bag model equation of state considering of non-zero strange quark mass $(m_{s})$ in the framework of modified $f(R,T)$…

General Relativity and Quantum Cosmology · Physics 2024-05-22 Debadri Bhattacharjee , Pradip Kumar Chattopadhyay

We describe a midi-superspace quantization scheme for generic single horizon black holes in which only the spatial diffeomorphisms are fixed. The remaining Hamiltonian constraint yields an infinite set of decoupled eigenvalue equations: one…

General Relativity and Quantum Cosmology · Physics 2009-11-11 J. Gegenberg , G. Kunstatter , R. D. Small

Hidden Markov Models (HMMs) can be accurately approximated using co-occurrence frequencies of pairs and triples of observations by using a fast spectral method in contrast to the usual slow methods like EM or Gibbs sampling. We provide a…

Machine Learning · Statistics 2012-03-29 Dean P. Foster , Jordan Rodu , Lyle H. Ungar

We investigate the impact of an external pressure on the structure of self-gravitating polytropes for axially symmetric ellipsoids and rings. The confinement of the fluid by photons is accounted for through a boundary condition on the…

Solar and Stellar Astrophysics · Physics 2017-11-15 J. -M. Huré , F. Hersant , G. Nasello

In the spherically symmetric case the Einstein field equations take on their simplest form for a matter-density rho = 1 / (8 pi r^2), from which a radial metric coefficient g_{rr} \propto r follows. The boundary of an object with such an…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Michael Petri

The cosmographic approach is adopted to determine the spatial curvature (i.e., $\Omega_K$) combining the latest released cosmic chronometers data (CC), the Pantheon sample of type Ia supernovae observations, and the baryon acoustic…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-08 En-Kun Li , Minghui Du , Lixin Xu

This paper introduces a novel boundary integral approach of shape uncertainty quantification for the Helmholtz scattering problem in the framework of the so-called parametric method. The key idea is to construct an integration grid whose…

Computational Engineering, Finance, and Science · Computer Science 2018-11-29 Yuval Harness

The hierarchical equations of motion (HEOM) provide a numerically exact approach for computing the reduced dynamics of a quantum system linearly coupled to a bath. We have found that HEOM contains temperature-dependent instabilities that…

Chemical Physics · Physics 2019-05-13 Ian S. Dunn , Roel Tempelaar , David R. Reichman

We complete the stability study of general relativistic spherically symmetric polytropic perfect fluid spheres, concentrating attention to the newly discovered polytropes containing region of trapped null geodesics. We compare the methods…

General Relativity and Quantum Cosmology · Physics 2020-05-14 Jan Hladík , Camilo Posada , Zdeněk Stuchlík

Supersymmetric quantum mechanics is well known to provide, together with the so-called shape invariance condition, an elegant method to solve the eigenvalue problem of some one-dimensional potentials by simple algebraic manipulations. In…

Condensed Matter · Physics 2009-10-28 Bertrand Berche , Ferenc Iglói

We exhibit a simple and explicit formula for the metric of an arbitrary static spherically symmetric perfect fluid spacetime. This class of metrics depends on one freely specifiable monotone non-increasing generating function. We also…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Shahinur Rahman , Matt Visser

At constant time $t$, we examine the Vaidya-Tikekar metric characterising a three-dimensional, extremely dense spheroidal star configuration. The static, spherically symmetric solution of Einstein's field equations can be expressed in…

General Relativity and Quantum Cosmology · Physics 2026-01-07 Naren Babu O. , Hemalatha. R , Narayanankutty Karuppath , Sabu M. C

This paper introduces a novel cosmological model aimed at probing the accelerated expansion of the late Universe through a unique parametrization of the deceleration parameter. We aim to constrain key cosmic parameters by integrating recent…

General Relativity and Quantum Cosmology · Physics 2024-08-14 Himanshu Chaudhary , Ujjal Debnath , G. Mustafa , S. K. Maurya , Farruh Atamurotov

As one of Bayesian analysis tools, Hidden Markov Model (HMM) has been used to in extensive applications. Most HMMs are solved by Baum-Welch algorithm (BWHMM) to predict the model parameters, which is difficult to find global optimal…

Machine Learning · Statistics 2018-11-09 L. Chang , Yacine Ouzrout , Antoine Nongaillard , Abdelaziz Bouras

A bouncing scenario of a flat homogeneous and isotropic universe is explored by using the reconstruction technique for the power-law parametrization of the Hubble parameter in a modified gravity theory with higher-order curvature and trace…

General Relativity and Quantum Cosmology · Physics 2023-04-03 J. K. Singh , Harshna Balhara , Kazuharu Bamba , J. Jena

We propose a novel hybrid high-order method (HHO) to approximate singularly perturbed fourth-order PDEs on domains with a possibly curved boundary. The two key ideas in devising the method are the use of a Nitsche-type boundary penalty…

Numerical Analysis · Mathematics 2021-12-07 Zhaonan Dong , Alexandre Ern