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Stellar pulsations and gravitational waves

Kostas Kokkotas (1997)

Banach Center Publications

Pulsating stars are important sources of information for astrophysics. Nearly every star undergoes some kind of pulsation from the early stages of its formation until the very late ones i.e. the catastrophic creation of a supercompact object (white dwarf, neutron star or black hole). Pulsations of supercompact objects are of great importance for relativistic astrophysics since these pulsations are accompanied by the emission of gravitational radiation. In this review we shall discuss various features...

Sui fondamenti dell’ottica relativistica

Giorgio Ferrarese, Rita Antonelli (2002)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Il lavoro deduce, in ambito relativistico, le proprietà fondamentali di un flusso luminoso (congruenza nulla) mediante tecniche anolonome reali [2,3] e precisamente: caratteristiche geometrico-cinematiche del flusso (assolute e relative), teorema di Sachs [6] e proprietà dei nastri luminosi, con particolare riguardo ai parametri ottici e di deformazione, in spazi-tempo particolari (stazionarietà relativa, flussi geodetici, riferimenti trasportati per parallelismo dalla luce).

Sulla legge di gravitazione universale. Nota I

Dionigi Galletto, Bruno Barberis (1984)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Without making recourse to Newton's law of gravitation and starting from the concept of gravitational force, the concepts of active gravitational mass and of passive gravitational mass are introduced. Furthermore it is proved that they can be identified and that in Newton's law of gravitation the linear dependence on masses necessarily follows from the principle of superposition of simultaneous forces and from Newton's third law of dynamics.

Sur la géométrie de la singularité initiale des espaces-temps plats globalement hyperboliques

Mehdi Belraouti (2014)

Annales de l’institut Fourier

On étudie le comportement asymptotique des niveaux d’une fonction temps quasi-concave, définie sur un espace-temps globalement hyperbolique maximal plat de dimension trois, admettant une hypersurface de Cauchy de genre ≥ 2 . On donne une réponse positive à une conjecture posée par Benedetti et Guadagnini dans [7]. Plus précisément, on montre que les niveaux d’une telle fonction temps convergent au sens de la topologie de Hausdorff-Gromov équivariante vers un arbre réel. On montre de plus que la limite...

Technicalities in the calculation of the 3rd post-Newtonian dynamics

Piotr Jaranowski (1997)

Banach Center Publications

Dynamics of a point-particle system interacting gravitationally according to the general theory of relativity can be analyzed within the canonical formalism of Arnowitt, Deser, and Misner. To describe the property of being a point particle one can employ Dirac delta distribution in the energy-momentum tensor of the system. We report some mathematical difficulties which arise in deriving the 3rd post-Newtonian Hamilton's function for such a system. We also offer ways to overcome partially these difficulties....

The closed Friedman world model with the initial and final singularities as a non-commutative space

Michael Heller, Wiesław Sasin (1997)

Banach Center Publications

The most elegant definition of singularities in general relativity as b-boundary points, when applied to the closed Friedman world model, leads to the disastrous situation: both the initial and final singularities form the single point of the b-boundary which is not Hausdorff separated from the rest of space-time. We apply Alain Connes' method of non-commutative geometry, defined in terms of a C*-algebra, to this case. It turns out that both the initial and final singularities can be analysed as...

The graded differential geometry of mixed symmetry tensors

Andrew James Bruce, Eduardo Ibarguengoytia (2019)

Archivum Mathematicum

We show how the theory of ℤ 2 n -manifolds - which are a non-trivial generalisation of supermanifolds - may be useful in a geometrical approach to mixed symmetry tensors such as the dual graviton. The geometric aspects of such tensor fields on both flat and curved space-times are discussed.

Currently displaying 301 – 320 of 377