Cutting out the cosmological middle man: general relativity in the light-cone coordinates

@article{Mitsou2020CuttingOT,
  title={Cutting out the cosmological middle man: general relativity in the light-cone coordinates},
  author={Ermis Mitsou and Giuseppe Fanizza and Nastassia Grimm and Jaiyul Yoo},
  journal={Classical and Quantum Gravity},
  year={2020},
  volume={38}
}
Analytical computations in relativistic cosmology can be split into two sets: time evolution relating the initial conditions to the observer’s light-cone and light propagation to obtain observables. Cosmological perturbation theory in the Friedmann–Lemaître–Robertson–Walker (FLRW) coordinates constitutes an efficient tool for the former task, but the latter is dramatically simpler in light-cone-adapted coordinates that trivialize the light rays toward the observer world-line. Here we point out… 

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References

SHOWING 1-10 OF 34 REFERENCES

A new approach to the propagation of light-like signals in perturbed cosmological backgrounds

We present a new method to compute the deflection of light rays in a perturbed FLRW geometry. We exploit the properties of the Geodesic Light Cone (GLC) gauge where null rays propagate at constant

An exact Jacobi map in the geodesic light-cone gauge

The remarkable properties of the recently proposed geodesic light-cone (GLC) gauge allow to explicitly solve the geodesic-deviation equation, and thus to derive an exact expression for the Jacobi map

The cosmological perturbation theory on the Geodesic Light-Cone background

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

Geodesic-light-cone coordinates and the Bianchi I spacetime

The geodesic-light-cone (GLC) coordinates are a useful tool to analyse light propagation and observations in cosmological models. In this article, we propose a detailed, pedagogical, and rigorous

Lensing in the geodesic light-cone coordinates and its (exact) illustration to an off-center observer in Lemaȋtre-Tolman-Bondi models

We present in this paper a new application of the geodesic light-cone (GLC) gauge for weak lensing calculations. Using interesting properties of this gauge, we derive an exact expression of the

Tetrad Formalism for Exact Cosmological Observables

The standard description of cosmological observables is incomplete, because it does not take into account the correct angular parametrization of the sky, i.e. the one determined by the observer

Lightcone Averaging and Precision Cosmology

The first objective of this thesis is to fill the lack in cosmology of a description on the past light cone: the null hypersurface on which observed signals propagate. Its second goal is to evaluate

A numerical relativity scheme for cosmological simulations

Cosmological simulations involving the fully covariant gravitational dynamics may prove relevant in understanding relativistic/non-linear features and, therefore, in taking better advantage of the

Light-cone averaging in cosmology: formalism and applications

We present a general gauge invariant formalism for defining cosmological averages that are relevant for observations based on light-like signals. Such averages involve either null hypersurfaces