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Isotropy theorem for cosmological vector fields

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López Maroto, Antonio and Ruiz Cembranos, José Alberto and Nuñez Jareño, Santos José and Hallabrin, C. (2012) Isotropy theorem for cosmological vector fields. Physical Review D, 86 (2). ISSN 1550-7998

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Official URL: http://dx.doi.org/10.1103/PhysRevD.86.021301


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Abstract

We consider homogeneous Abelian vector fields in an expanding universe. We find a mechanical analogy in which the system behaves as a particle moving in three dimensions under the action of a central potential. In the case of bounded and rapid evolution compared to the rate of expansion, we show-by making use of the virial theorem-that for an arbitrary potential and polarization pattern, the average energy-momentum tensor is always diagonal and isotropic despite the intrinsic anisotropic evolution of the vector field. For simple power law potentials of the form V = lambda(A(mu)A(mu))(n), the average equation of state is found to be w = (n - 1)/(n + 1). This implies that vector coherent oscillations could act as natural dark matter or dark energy candidates. Finally, we show that under very general conditions, the average energy-momentum tensor of a rapidly evolving bounded vector field in any background geometry is always isotropic and has the perfect fluid form for any locally inertial observer.


Item Type:Article
Additional Information:

© 2012 American Physical Society.
This work has been supported by MICINN (Spain) under Project Nos. FIS 2008-01323, FIS2011-23000, FPA2011- 27853 01 and Consolider-Ingenio MULTIDARK under Contract No. CSD2009-00064.

Uncontrolled Keywords:Cp Conservation, Inflation, Clusters
Subjects:Sciences > Physics
ID Code:25826
Deposited On:12 Jun 2014 15:37
Last Modified:19 Nov 2014 12:53

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