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Two-fluid dark matter models

T. Harko, F. S. N. Lobo

Abstract
We investigate the possibility that dark matter is a mixture of two noninteracting perfect fluids, with different four-velocities and thermodynamic parameters. The two-fluid model can be described as an effective single anisotropic fluid, with distinct radial and tangential pressures. The basic equations describing the equilibrium structure of the two-fluid dark matter model, and of the tangential velocity of test particles in stable circular orbits, are obtained for the case of a spherically symmetric static geometry. By assuming a nonrelativistic kinetic model for the dark matter particles, the density profile and the tangential velocity of the dark matter mixture are obtained by numerically integrating the gravitational field equations. The cosmological implications of the model are also briefly considered, and it is shown that the anisotropic two-fluid model isotropizes in the large-time limit.

Keywords
Modified: theories: of: gravity - Fundamental: problems: and: general: formalism - Canonical: formalism: Lagrangians: and: variational: principles

Physical Review D
Volume 83, Issue 12, Page 124051_1
2011 June

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia