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Cosmology can be viewed as geodesic motion in an appropriate metric on an `augmented' target space; here we obtain these geodesics from an effective relativistic particle action. As an application, we find some exact (flat and curved)…

High Energy Physics - Theory · Physics 2016-09-06 J. G. Russo , P. K. Townsend

The geometric picture of the star-product based on its Fourier representation kernel is utilized in the evaluation of chains of star-products and the intuitive appreciation of their associativity and symmetries. Such constructions appear…

High Energy Physics - Theory · Physics 2009-10-02 Cosmas Zachos

This is the fourth paper in a series that attempt to put forward a consistent framework for modelling solid regions in neutron stars. Here we turn our attention to axial perturbations of spherically symmetric spacetimes using a gauge…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Max Karlovini , Lars Samuelsson

Space-Time in general relativity is a dynamical entity because it is subject to the Einstein field equations. The space-time metric provides different geometrical structures: conformal, volume, projective and linear connection. A deep…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Ignacio Sanchez-Rodriguez

We present a new model of large-scale multilayer convection in solar type stars. This model allows us to understand such self-similar structures observed at solar surface as granulation, supergranulation and giant cells. We study the…

Solar and Stellar Astrophysics · Physics 2010-12-17 E. A. Bruevich , I. K. Rozgacheva

Galactic nuclei, the densest stellar environments in the Universe, exhibit a complex geometrical structure. The stars orbiting the central supermassive black hole follow a mass segregated distribution both in the radial distance from the…

Astrophysics of Galaxies · Physics 2023-10-24 Hanxi Wang , Bence Kocsis

Anisotropic spherically symmetric solutions within the framework of the Brans-Dicke theory are uncovered through a unique gravitational decoupling approach involving a minimal geometric transformation. This transformation effectively…

General Relativity and Quantum Cosmology · Physics 2023-11-01 Kazuharu Bamba , M. Z. Bhatti , Z. Yousaf , Z. Shoukat

Model fitting is frequently used to determine the shape of galaxies and the point spread function, for examples, in weak lensing analyses or morphology studies aiming at probing the evolution of galaxies. However, the number of parameters…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-03 Guoliang Li , Bo Xin , Wei Cui

For the spherically symmetric Stephani cosmological model with an accelerated expansion, we investigate the main scenarios of the test particle and photon motion. We show that a comoving observer sees an appropriate picture. In the case of…

General Relativity and Quantum Cosmology · Physics 2021-06-14 Irina Bormotova , Elena Kopteva , Zdenek Stuchlik

The semi-classical approach to the quantum geometrodynamical model is used for the description of the properties of the universe on extremely small spacetime scales. Quantum theory for a homogeneous, isotropic and closed universe is…

General Relativity and Quantum Cosmology · Physics 2009-10-21 V. E. Kuzmichev , V. V. Kuzmichev

We present a class of general prolate and oblate spheroidal spacetimes for the description of cosmic structures in the Universe. They are exact geometries which represent, in an appropriated way, the imbedding of spheroidal matter-energy…

General Relativity and Quantum Cosmology · Physics 2017-01-27 Ezequiel F. Boero , Osvaldo M. Moreschi

The universe displays a three-dimensional pattern of hot and cold spots in the radiation remnant from the big bang. The global geometry of the universe can be revealed in the spatial distribution of these spots. In a topologically compact…

Astrophysics · Physics 2009-10-30 Janna Levin , Evan Scannapieco , Giancarlo de Gasperis , Joseph Silk , John D. Barrow

In the present study we search for a new stellar model with spherically symmetric matter and charged distribution under general relativistic framework. The model represents a compact star of embedding class one. The solutions obtain here…

General Relativity and Quantum Cosmology · Physics 2017-03-08 S. K. Maurya , Y. K. Gupta , Saibal Ray , Debabrata Deb

Spectral synthesis is a powerful tool with which to find the fundamental parameters of stars. Models are usually restricted to single values of temperature and gravity, and assume spherical symmetry. This approximation breaks down for…

Solar and Stellar Astrophysics · Physics 2024-06-27 Benjamin Montesinos

A simple geometrical model is presented for the gravity-driven motion of a single particle on a rough inclined surface. Adopting a simple restitution law for the collisions between the particle and the surface, we arrive at a model in which…

Soft Condensed Matter · Physics 2009-10-31 Giovani L. Vasconcelos , J. J. P. Veerman

After giving an overview of the history and idea of neutron stars, I shall introduce, in part one of my lectures, a representative collection of models for the equation of state of superdense neutron star matter, which account for various…

Astrophysics · Physics 2007-05-23 Fridolin Weber , Norman K. Glendenning

In this review we discuss self-consistent methods to calculate the global structure of strongly magnetised neutron stars within the general-relativistic framework. We outline why solutions in spherical symmetry cannot be applied to strongly…

Nuclear Theory · Physics 2021-09-01 Debarati Chatterjee , Jerome Novak , Micaela Oertel

In this work we present all the possible solutions for a static cylindrical symmetric spacetime in the Einstein-Aether (EA) theory. As far as we know, this is the first work in the literature that considers cylindrically symmetric solutions…

General Relativity and Quantum Cosmology · Physics 2022-01-05 R. Chan , M. F. A. da Silva

A tetrad-based procedure is presented for solving Einstein's field equations for spherically-symmetric systems; this approach was first discussed by Lasenby et al. in the language of geometric algebra. The method is used to derive metrics…

General Relativity and Quantum Cosmology · Physics 2015-05-27 Roshina Nandra , Anthony N. Lasenby , Michael P. Hobson

We have found some new exact static spherically symmetric interior solutions of metric $f(R)$ gravitational theories describing the equilibrium configuration of a star. Then the solution is matched to the exterior solution and thus gives a…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Ali Shojai , Fatimah Shojai