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arXiv · 2604.09262

The near equilibrium Einstein-Boltzmann system with a simplified collision term

Philip Semrén·Michael Bradley·João M. S. Oliveira·M. Piedade Machado Ramos
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Abstract

A simplified relativistic kinetic theory for gases with internal degrees of freedom, based on a BGK-type collision term, is considered. First the Boltzmann equation is rewritten in tetrad form and then thermal coefficients are determined to first order in the Chapman-Enskog expansion for general spacetimes. The results are used to construct a self-consistent system of first order differential equations, equivalent to the Einstein-Boltzmann system, for some spatially homogeneous models with viscosity and heat flow.

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Philip Semrén, Michael Bradley, João M. S. Oliveira, M. Piedade Machado Ramos. 2026-04-10. The near equilibrium Einstein-Boltzmann system with a simplified collision term. https://arxiv.org/abs/2604.09262

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