Matter Growth in Imperfect Fluid Cosmology. (arXiv:1903.03383v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Zimdahl_W/0/1/0/all/0/1">Winfried Zimdahl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Velten_H/0/1/0/all/0/1">Hermano Velten</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Algoner_W/0/1/0/all/0/1">William C. Algoner</a>
Extensions of Einstein’s General Relativity (GR) can formally be given a GR
structure in which additional geometric degrees of freedom are mapped on an
effective energy-momentum tensor. The corresponding effective cosmic medium can
then be modeled as an imperfect fluid within GR. The imperfect fluid structure
allows us to include, on a phenomenological basis, anisotropic stresses and
energy fluxes which are considered as potential signatures for deviations from
the cosmological standard $Lambda$-cold-dark-matter ($Lambda$CDM) model. As
an example, we consider the dynamics of a scalar-tensor extension of the
standard model, the $e_{Phi}Lambda$CDM model. We constrain the magnitudes of
anisotropic pressure and energy flux with the help of redshift-space distortion
(RSD) data for the matter growth function $f sigma_8$.
Extensions of Einstein’s General Relativity (GR) can formally be given a GR
structure in which additional geometric degrees of freedom are mapped on an
effective energy-momentum tensor. The corresponding effective cosmic medium can
then be modeled as an imperfect fluid within GR. The imperfect fluid structure
allows us to include, on a phenomenological basis, anisotropic stresses and
energy fluxes which are considered as potential signatures for deviations from
the cosmological standard $Lambda$-cold-dark-matter ($Lambda$CDM) model. As
an example, we consider the dynamics of a scalar-tensor extension of the
standard model, the $e_{Phi}Lambda$CDM model. We constrain the magnitudes of
anisotropic pressure and energy flux with the help of redshift-space distortion
(RSD) data for the matter growth function $f sigma_8$.
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