Image rotation from lensing

Francfort, Jérémie; Cusin, Giulia; Durrer, Ruth

doi:10.1088/1361-6382/ac33ba

Cited by 5 publications

(22 citation statements)

References 27 publications

(68 reference statements)

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“…However, it is a very subtle effect and it is also very challenging to know the original orientation of the sources. There are however some proposals using the polarisation of radio-galaxies (Francfort et al 2021). Here we provide both the fundamental lensing quantities and the detailed redshift perturbations so that the user can reconstruct any physical or observable quantities of interest.…”

Section: Relativistic Ray Tracing and Catalogue Creationmentioning

confidence: 99%

The RayGalGroupSims cosmological simulation suite for the study of relativistic effects: An application to lensing-matter clustering statistics

Breton

Corasaniti

Allingham

et al. 2022

A&A

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Context. General relativistic effects on the clustering of matter in the Universe provide a sensitive probe of cosmology and gravity theories that can be tested with the upcoming generation of galaxy surveys. These will require the availability of accurate model predictions, from large linear scales to small non-linear ones. Aims. Here, we present a suite of large-volume high-resolution N-body simulations specifically designed to generate light-cone data for the study of relativistic effects on lensing-matter observables without the use of simplifying approximations. As a case study application of these data, we perform an analysis of the relativistic contributions to the lensing-matter power spectra and cross-power spectra. Methods. The RayGalGroupSims suite (RAYGAL for short) consists of two N-body simulations of (2625 h−1 Mpc)3 volume with 40963 particles of a standard flat ΛCDM model and a non-standard wCDM phantom dark energy model with a constant equation of state. Light-cone data from the simulations have been generated using a parallel ray-tracing algorithm that has integrated more than 1 billion geodesic equations without the use of the flat-sky or Born approximation. Results. Catalogues and maps with relativistic weak lensing that include post-Born effects, magnification bias (MB), and redshift-space distortions (RSDs) due to gravitational redshift, Doppler, transverse Doppler, and integrated Sachs-Wolfe–Rees-Sciama effects are publicly released. Using this dataset, we are able to reproduce the linear and quasi-linear predictions from the CLASS relativistic code for the ten power spectra and cross-spectra (3 × 2 points) of the matter-density fluctuation field and the gravitational convergence at z = 0.7 and z = 1.8. We find a 1–30% level contribution from both MB and RSDs to the matter power spectrum, while the fingers-of-God effect is visible at lower redshift in the non-linear regime. Magnification bias also contributes at the 10−30% level to the convergence power spectrum, leading to a deviation between the shear power spectrum and the convergence power spectrum. Magnification bias also plays a significant role in the galaxy-galaxy lensing by decreasing the density-convergence spectra by 20% and coupling non-trivial configurations (such as the configuration with the convergence at the same redshift as the density, or at even lower redshifts). Conclusions. The cosmological analysis shows that the relativistic 3 × 2 points approach is a powerful cosmological probe. Our unified approach to relativistic effects is an ideal framework for the investigation of gravitational effects in galaxy studies (e.g., clustering and weak lensing) as well as their effects in galaxy cluster, group, and void studies (e.g., gravitational redshifts and weak lensing) and cosmic microwave background studies (e.g., integrated Sachs-Wolfe–Rees-Sciama and weak lensing).

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Section: Relativistic Ray Tracing and Catalogue Creationmentioning

confidence: 99%

The RayGalGroupSims cosmological simulation suite for the study of relativistic effects: An application to lensing-matter clustering statistics

Breton

Corasaniti

Allingham

et al. 2022

A&A

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“…Regarding gravitational lensing analysis, Francfort et al obtained a formula that can be employed in such a situation, i.e., in cases when the original orientations of galaxies are known [4]. However, their formula is for shear, a variable used in the gravitational lensing effect.…”

Section: Jcap09(2023)044mentioning

confidence: 99%

“…Thus, we can use this information to our advantage to measure the lensing effect more accurately, as pointed out in refs. [3][4][5]. Therefore, the position of dark matter at the Bullet Cluster may be corrected if we reanalyze the gravitational lensing effect with the help of the polarization data of radio waves, which would be available in the future [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

New method to revisit the gravitational lensing analysis of the Bullet Cluster using radio waves

Yoon,

Park,

Hwang

2023

J. Cosmol. Astropart. Phys.

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Gravitational lensing studies of the Bullet Cluster suggested convincingly in favor of the existence of dark matter. However, it was performed without the knowledge of the original orientation of each galaxy before gravitational lensing. A potential improvement to this issue lies in the measurement of the original orientation from the polarization direction of radio waves emitted from each galaxy. In this context, Francfort et al. derived a formula that can utilize the information about the original orientation of each galaxy to obtain what is called shear. However, we demonstrate that shear in their formula should be replaced by reduced shear when the change in sizes of images of galaxies is taken into account. As the previous gravitational lensing analysis of the Bullet Cluster used reduced shear, we suggest applying our improved formula directly for the reanalysis once we obtain the polarization direction of radio waves. In particular, we show that our new formula can yield a more accurate analysis than the previous one, if the polarization direction can be measured more precisely than 10°. Moreover, the approach discussed in this work is generically applicable to the gravitational lensing analysis of clusters, not only limited to the Bullet Cluster.

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“…We expect the redshift dependent δα power spectrum to be directly related to the shear power spectrum. [21] We observe that our present analysis is only valid for weak gravitational fields, weak lensing. It might be interesting to study if also for strong lenses in the presence of several images and a realistic lens model.…”

Section: Discussionmentioning

confidence: 76%

Image Rotation from weak Lensing

Francfort,

Cusin,

Durrer

2021

Preprint

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Forthcoming radio surveys will include full polarisation information, which can be potentially useful for weak lensing observations. We propose a new method to measure the (integrated) gravitational field between a source and the observer, by looking at the angle between the morphology of a radio galaxy and the orientation of the polarisation. For this we use the fact that, while the polarisation of a photon is parallel transported along the photon geodesic, the infinitesimal shape of the source, e.g. its principal axis in the case of an ellipse, is Lie transported. As an example, we calculate the rotation of the shape vector with respect to the polarisation direction which is generated by lensing by a distribution of foreground Schwarzschild lenses. For radio galaxies, the intrinsic morphological orientation of a source and its polarised emission are correlated. It follows that observing both the polarisation and the morphological orientation provides information on both the unlensed source orientation and on the gravitational potential along the line of sight.

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Image rotation from lensing

Cited by 5 publications

References 27 publications

The RayGalGroupSims cosmological simulation suite for the study of relativistic effects: An application to lensing-matter clustering statistics

The RayGalGroupSims cosmological simulation suite for the study of relativistic effects: An application to lensing-matter clustering statistics

New method to revisit the gravitational lensing analysis of the Bullet Cluster using radio waves

Image Rotation from weak Lensing

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