Tag Archives: perturbations

On the mass of compact rotating stars

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Amending the computation of the mass of compact rotating bodies with non-zero energy density at the surface.

Borja Reina

Borja Reina is a PhD fellow at the University of the Basque Country (UPV/EHU).

A proper understanding of rotating bodies in General Relativity (GR) is fundamental for many astrophysical situations. The original relativistic treatment of rotating compact stars in equilibrium is due to Hartle, back in 1967. It constitutes the basis of most of the analytical approaches and is widely used to construct numerical schemes in axial symmetry.

Hartle’s scheme depicts the equilibrium (stationary regime) Continue reading →

A unified description of the second order cosmological density contrast

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In this paper the authors introduce a new way of expressing the relativistic density contrast of matter perturbations in four commonly used gauges, both at first and second orders.

Julien Larena

Dr Julien Larena is a senior lecturer in the Department of Mathematics at Rhodes University, South Africa. His research is centred on relativistic corrections to cosmology, tests of the Copernican principle, and the backreaction issue in cosmology.

This new method is very interesting, since it provides a unified treatment of the density contrast in the various gauges, thus allowing a straightforward comparison of results obtained by other authors in different gauges. This should be useful when computing non-trivial effects such as the properties Continue reading →