Relativistic perturbations in $Λ$CDM: Eulerian & Lagrangian approaches [CL]

http://arxiv.org/abs/1505.04782


We study the relativistic dynamics of a pressure-less and irrotational fluid of dark matter (CDM) with a cosmological constant ($\Lambda$), up to second order in cosmological perturbation theory. In our analysis we also account for primordial non-Gaussianity. We consider three gauges: the synchronous-comoving gauge, the Poisson gauge and the total matter gauge, where the first is the unique relativistic Lagrangian frame of reference, and the latters are convenient choices for Eulerian frames. Our starting point is the metric and fluid variables in the Poisson gauge. We then perform a gauge-transformation to the synchronous-comoving gauge, and subsequently to the total matter gauge. Our expressions for the metrics, densities, velocities, and the gauge generators are novel and coincide with known results in the limit of a vanishing cosmological constant.

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E. Villa and C. Rampf
Tue, 19 May 15
18/78

Comments: 37 pages