The Cosmological Perturbation Theory on the Geodesic Light-Cone background

Abstract

Inspired by the fully non-linear Geodesic Light-Cone (GLC) gauge, we consider its analogous set of coordinates which describes the unperturbed Universe. Given this starting point, we then build a cosmological perturbation theory on top of it, study the gauge transformation properties related to this new set of perturbations and show the connection with standard cosmological perturbation theory. In particular, we obtain which gauge in standard perturbation theory corresponds to the GLC gauge, and put in evidence how this is a useful alternative to the standard Synchronous Gauge. Moreover, we exploit several viable definitions for gauge invariant combinations. Among others, we build the gauge invariant variables such that their values equal the ones of linearized GLC gauge perturbations. This choice is motivated by two crucial properties of the GLC gauge: i) it admits simple expressions for light-like observables, e.g. redshift and angular distance, at fully non-linear level and ii) the GLC proper time coincides with the one of a free-falling observer. Thanks to the first property, exact expressions can then be easily expanded at linear order to obtain linear gauge invariant expression for the chosen observable. Moreover, the second feature naturally provides gauge invariant expressions for physical observables in terms of the time as measured by such free-falling observer. Finally, we explicitly show all these aspects for the case of the linearized angular distance-redshift relation.

26 pages, no figures. Inconsequential modification of an equation. Comments and references added. Version accepted for publication in JCAP

References in corpus (6)

• The DESI Experiment Part I: Science,Targeting, and Survey Design
• Galaxy number counts to second order and their bispectrum
• Do stochastic inhomogeneities affect dark-energy precision measurements?
• Large-Scale Structure Observables in General Relativity
• The luminosity distance-redshift relation up to second order in the Poisson gauge with anisotropic stress
• Vector and Tensor Contributions to the Luminosity Distance

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• Gauge invariance on the light-cone: curvature perturbations and radiative degrees of freedom
• Accurate relativistic observables from post-processing light cone catalogues
• Non-commutative coordinates from quantum gravity
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• $\delta N$ formalism on the past light-cone
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