Gauge-transformation properties of cosmological observables and its application to the light-cone average
Jaiyul Yoo,Ruth Durrer +1 more
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In this paper, the authors show that cosmological observables are invariant scalars under diffeomorphisms and their theoretical description is gauge-invariant, only at linear order in perturbations.Abstract:
Theoretical descriptions of observable quantities in cosmological perturbation theory should be independent of coordinate systems. This statement is often referred to as gauge-invariance of observable quantities, and the sanity of their theoretical description is verified by checking its gauge-invariance. We argue that cosmological observables are invariant scalars under diffeomorphisms and their theoretical description is gauge-invariant, only at linear order in perturbations. Beyond linear order, they are usually not gauge-invariant, and we provide the general law for the gauge-transformation that the perturbation part of an observable does obey. We apply this finding to derive the second-order expression for the observational light-cone average in cosmology and demonstrate that our expression is indeed invariant under diffeomorphisms.read more
Citations
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Gauge-Invariant Cosmological Perturbations
TL;DR: The physical interpretation of perturbations of homogeneous, isotropic cosmological models in the early Universe, when the perturbation is larger than the particle horizon, is clarified by defining a complete set of gauge-invariant variables as discussed by the authors.
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CMB-lensing beyond the leading order: temperature and polarization anisotropies
TL;DR: In this paper, weak lensing corrections to the cosmic microwave background temperature and polarization anisotropies were investigated, and it was shown that the contribution from the rotation of the polarization direction between the emission at the source and the detection at the observer is dominant.
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Generalized covariant prescriptions for averaging cosmological observables
Giuseppe Fanizza,Giuseppe Fanizza,Maurizio Gasperini,Maurizio Gasperini,Giovanni Marozzi,Giovanni Marozzi,Gabriele Veneziano,Gabriele Veneziano +7 more
TL;DR: In this paper, two new covariant and general prescriptions for averaging scalar observables on spatial regions typical of the observed sources and intersecting the past light-cone of a given observer are presented.
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Galaxy two-point correlation function in general relativity
TL;DR: In this article, the authors performed theoretical and numerical studies of the full relativistic two-point galaxy correlation function, considering the linear-order scalar and tensor perturbation contributions and the wide-angle effects.
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Gauge-Invariant Formalism of Cosmological Weak Lensing
TL;DR: In this article, the authors present the gauge-invariant formalism of cosmological weak lensing, accounting for all the relativistic effects due to the scalar, vector, and tensor perturbations at the linear order.
References
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Book
Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity
TL;DR: In this paper, the General Theory of Relativity and Feneral Relativity are discussed, as well as applications of feneral relativity in cosmology and cosmology.
Journal ArticleDOI
Gauge Invariant Cosmological Perturbations
TL;DR: The physical interpretation of perturbations of homogeneous, isotropic cosmological models in the early Universe, when the perturbation is larger than the particle horizon, is clarified by defining a complete set of gauge-invariant variables as discussed by the authors.
Journal ArticleDOI
Linear power spectrum of observed source number counts
Anthony Challinor,Antony Lewis +1 more
TL;DR: In this paper, the observable number of sources per solid angle and redshift to the underlying proper source density and velocity, background evolution, and line-of-sight potentials were derived.
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What galaxy surveys really measure
Camille Bonvin,Ruth Durrer +1 more
TL;DR: In this paper, the authors compute the quantity which is truly measured in a large galaxy survey, taking into account the effects coming from the fact that we actually observe galaxy redshifts and sky positions and not true spatial positions.