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arXiv · 1603.04291

Extending the LCDM model through shear-free anisotropies

Thiago S. Pereira·Davincy T. Pabon
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Abstract

If the spacetime metric has anisotropic spatial curvature, one can afford to expand the universe isotropically, provided that the energy-momentum tensor satisfy a certain con- straint. This leads to the so-called shear-free metrics, which have the interesting property of violating the cosmological principle while still preserving the isotropy of the cosmic mi- crowave background (CMB) radiation. In this work we show that shear-free cosmologies correspond to an attractor solution in the space of models with anisotropic spatial curva- ture. Through a rigorous definition of linear perturbation theory in these spacetimes, we show that shear-free models represent a viable alternative to describe the large-scale evo- lution of the universe, leading, in particular, to a kinematically equivalent Sachs-Wolfe effect. Alternatively, we discuss some specific signatures that shear-free models would imprint on the temperature spectrum of CMB.

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Thiago S. Pereira, Davincy T. Pabon. 2016-03-14. Extending the LCDM model through shear-free anisotropies. https://doi.org/10.1142/s0217732316400095

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