Full-sky weak lensing: a nonlinear post-Friedmann treatment

Gressel, Hedda Alice; Bonvin, Camille; Bruni, Marco; Bacon, David

doi:10.1088/1475-7516/2019/05/045

Cited by 15 publications

(11 citation statements)

References 63 publications

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“…Such effects were already taken into con-sideration in Lepori et al (2020) on the convergence PDF by means of ray-tracing through a relativistic N-body simulation but a detailed comparison with the Newtonian PDF was not performed. Nevertheless, should this be done and a significant effect be found, those type of corrections could be computed within the post-Friedmann formalism for which a re-definition of the usual weak-lensing fields was recently performed in Gressel et al (2019). Another crucial correction to be taken into account comes from the fact that the observed field, the lensing-induced ellipticities of galaxies, correspond to the reduced shear g = γ/(1 + κ) rather than the shear itself.…”

Section: Discussionmentioning

confidence: 99%

Probability distribution function of the aperture mass field with large deviation theory

Barthelemy,

Codis,

Bernardeau

2020

Preprint

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In the context of tomographic cosmic shear surveys, a theoretical model for the one-point statistics of the aperture mass (Map) is developed. This formalism is based on the application of the large deviation principle to the projected matter density field and more specifically to the angular aperture masses. The latter holds the advantage of being an observable that can be directly extracted from the observed shear field and to be, by construction, independent from the long wave modes. Furthermore we show that, with the help of a nulling procedure based on the so-called BNT transform, it is possible to build observables that depend only on a finite range of redshifts making them also independent from the small-scale modes. This procedure makes predictions for the shape of the one-point Probability Distribution Function of such an observable very accurate, comparable to what had been previously obtained for 3D observables. Comparisons with specific simulations reveal however inconsistent results showing that synthetic lensing maps were not accurate enough for such refined observables. It points to the need for more precise dedicated numerical developments whose performances could be benchmarked with such observables. We furthermore review the possible systematics that could affect such a formalism in future weak-lensing surveys like Euclid, notably the impact of shape noise as well as leading corrections coming from lens-lens couplings, geodesic deviation, reduced shear and magnification bias.

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Section: Discussionmentioning

confidence: 99%

Probability distribution function of the aperture mass field with large deviation theory

Barthelemy,

Codis,

Bernardeau

2020

Preprint

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“…Therefore, besides the gravitomagnetic force acting on massive particles, it is also important to study how vector modes, as well as other GR effects, could influence the photon trajectories on nonlinear scales, and what is the consequent impact on observables, e.g. lensing (Thomas et al 2015a;Saga et al 2015;Gressel et al 2019). This requires the implementation of general-relativistic ray tracing algorithms (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…The impact of vector modes on LSS observables is expected to be small relative to the scalar perturbations, both from perturbative (Lu et al 2009) and non-perturbative analyses (Bruni et al 2014;Adamek et al 2016b), although it can represent a new systematic which needs to be taken into account (Bonvin et al 2018). For instance, their effect on gravitational lensing seems to be not strong enough to be detectable by current observations (Thomas et al 2015a;Saga et al 2015;Gressel et al 2019), and the imprints of the vector potential in the angular power spectrum and bispectrum of galaxies are also weak (Durrer & Tansella 2016;Jolicoeur et al 2019), although a vector perturbation can be isolated from the full signal if it violates statistical isotropy and defines a preferred frame (see, e.g., Tansella et al 2018). On the other hand, the vector potential power spectrum is known to peak around the equality scale (Lu et al 2009), and its behaviour as well as impact on observables at highly nonlinear scales remains largely unexplored, although deviations from perturbation theory can be significant (Bruni et al 2014).…”

Section: Introductionmentioning

confidence: 95%

Vector modes in $Λ$CDM: the gravitomagnetic potential in dark matter haloes from relativistic $N$-body simulations

Barrera-Hinojosa,

Li,

Bruni

et al. 2020

Preprint

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We investigate the inherently nonlinear transverse modes of the gravitational and velocity fields in ΛCDM cosmology, based on a high-resolution simulation performed using the adaptive-mesh refinement general-relativistic N -body code GRAMSES. We study the generation of vorticity in the dark matter velocity field at low redshift, providing power-law fits to the shape and evolution of its power spectrum from large sub-horizon scales to deeply nonlinear scales. By analysing the gravitomagnetic vector potential, a purely relativistic vector mode of the gravitational field that is absent in Newtonian simulations of structure formation, in dark matter haloes with masses ranging from ∼ 10 12.5 h −1 M to ∼ 10 15 h −1 M , we find that the magnitude of this vector correlates with the halo mass, peaking in the inner regions and decreasing towards their outskirts. Nevertheless, on average, its ratio against the scalar gravitational potential remains fairly constant inside the haloes, below percent level, decreasing roughly linearly with redshift at z < 3 and showing a weak dependence on halo mass. Furthermore, we show that the gravitomagnetic acceleration in dark matter haloes peaks towards the core and reaches almost 10 −10 h cm/s 2 in the most massive halo of the simulation. However, regardless of the halo mass, the ratio between the magnitudes of the gravitomagnetic force and the standard gravitational force is typically at around the 10 −3 level in the innermost parts of the haloes and drops by up to one order of magnitude at the outskirts. This ratio shows a very weak dependence on redshift. This result confirms that the gravitomagnetic field has a negligible effect on cosmic structure formation, even for the most massive structures, although its behaviour in low density regions such as voids remains to be explored. In addition, its effects on photons and therefore observations remains to be understood in detail in the future.

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“…These studies are still in their infancy but they are addressed with several approaches most of which we briefly sketched above. A non-comprehensive list includes [18][19][20][21][22][23][24][25]. Despite being too early to draw definitive conclusions, it seems that the codes that approximate GR dynamics are in agreement with Newtonian simulations for what concerns weak-lensing observables [18,25] but a modification in the statistics of the luminosity distance [23] was found.…”

Section: Introductionmentioning

confidence: 99%

Isolating non-linearities of light propagation in inhomogeneous cosmologies

Grasso,

Villa,

Korzyński

et al. 2021

Preprint

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A new formulation for light propagation in geometric optics by means of the Bi-local Geodesic Operators is considered. We develop the BiGONLight Mathematica package, uniquely designed to apply this framework to compute optical observables in Numerical Relativity. Our package can be used for light propagation on a wide range of scales and redshifts and accepts numerical as well as analytical input for the spacetime metric. In this paper we focus on two cosmological observables, the redshift and the angular diameter distance, specializing our analysis to a wall universe modeled within the post-Newtonian approximation. With this choice and the input metric in analytical form, we are able to estimate non-linearities of light propagation by comparing and isolating the contributions coming from Newtonian and post-Newtonian approximations as opposed to linear perturbation theory. We also clarify the role of the dominant post-Newtonian contribution represented by the linear initial seed which, strictly speaking, is absent in the Newtonian treatment. We found that post-Newtonian non-linear corrections are below 1%, in agreement with previous results in the literature.

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Full-sky weak lensing: a nonlinear post-Friedmann treatment

Cited by 15 publications

References 63 publications

Probability distribution function of the aperture mass field with large deviation theory

Probability distribution function of the aperture mass field with large deviation theory

Vector modes in $Λ$CDM: the gravitomagnetic potential in dark matter haloes from relativistic $N$-body simulations

Isolating non-linearities of light propagation in inhomogeneous cosmologies

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