7,217 research outputs found

    Generalised hyperbolicity in spacetimes with string-like singularities

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    In this paper we present well-posedness results of the wave equation in H1H^{1} for spacetimes that contain string-like singularities. These results extend a framework able to characterise gravitational singularities as obstruction to the dynamics of test fields rather than point particles. In particular, we discuss spacetimes with cosmic strings and the relation of our results to the Strong Cosmic Censorship Conjecture.Comment: Accepted for publication in Classical and Quantum Gravit

    Quantised vortices and mutual friction in relativistic superfluids

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    We consider the detailed dynamics of an array of quantised superfluid vortices in the framework of general relativity, as required for quantitative modelling of realistic neutron star cores. Our model builds on the variational approach to relativistic (multi-) fluid dynamics, where the vorticity plays a central role. The description provides a natural extension of, and as it happens a better insight into, existing Newtonian models. In particular, we account for the mutual friction associated with scattering of a second "normal" component in the mixture off of the superfluid vortices.Comment: 9 pages, RevTe

    Hawking's singularity theorem for C1,1C^{1,1}-metrics

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    We provide a detailed proof of Hawking's singularity theorem in the regularity class C1,1C^{1,1}, i.e., for spacetime metrics possessing locally Lipschitz continuous first derivatives. The proof uses recent results in C1,1C^{1,1}-causality theory and is based on regularisation techniques adapted to the causal structure.Comment: 19 pages, LaTeX; v2: corrected Lemma 4.2; v3: typos corrected, final versio

    Global Gronwall Estimates for Integral Curves on Riemannian Manifolds

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    We prove Gronwall-type estimates for the distance of integral curves of smooth vector fields on a Riemannian manifold. Such estimates are of central importance for all methods of solving ODEs in a verified way, i.e., with full control of roundoff errors. Our results may therefore be seen as a prerequisite for the generalization of such methods to the setting of Riemannian manifolds.Comment: 4 pages, 1 figure, correction of some misprint
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