Weak-lensing B-modes as a probe of the isotropy of the universe

¹ Departamento de FísicaUniversidade Estadual de Londrina, 86051-990, Londrina Paraná, Brazil
e-mail: tspereira@uel.br
² Institut d’Astrophysique de Paris, Université Pierre & Marie Curie − Paris VI, CNRS-UMR 7095, 98bis Bd Arago, 75014 Paris, France
³ Sorbonne Universités, Institut Lagrange de Paris, 98bis boulevard Arago, 75014 Paris, France
e-mail: pitrou@iap.fr; uzan@iap.fr

Received: 26 August 2015
Accepted: 1 December 2015

Abstract

Aims. We use the angular power spectrum of B-modes of the weak-lensing shear as a tool for constraining late-time deviations of spatial isotropy in our Universe.

Methods. We used the formalism of weak lensing in arbitrary spacetimes.

Results. We find that off-diagonal correlations must exist between E-modes, B-modes, and convergence of the weak-lensing field, which allow one to reconstruct the eigendirections of anisotropic expansion. Focusing on future surveys, such as Euclid and the Square Kilometer Array (SKA), we find that observations can constrain the geometrical shear in units of the Hubble rate at the percent level or better. These observations offer a new and powerful method to probe our cosmological model, however, the power of this new technique still requires further investigations and a full analysis of signal-to-noise ratio.